Hi Performance Street Rod skills aren’t hard to learn and in many situations they’re almost simple. Unfortunately, its tough to tune a car with a set of braced up Weber carbs if you don’t know how to set up a single carb. By the same token, it’s impossible to cool down a high compression, radical big block engine if you’re having trouble cooling down your mom’s old Malibu.

In sports they call it ‘basic skills’, if you don’t have the basics down pat, you cant run the quick E.T’s. To make it worse still, there aren’t any many weekend workshops or places you can go to learn the basic skills of ‘engine tweaking’ and modifying your muscle car to cut down those tenths. No, there’s no university to teach you the skills of engine building, engine tuning and hot rodding, but there is a substitute for the ‘school of hard knocks’. Check out the following how-to guide, there’s a boxful of tips below to get you there quicker.

Metallic Materials

Metals are characterized by having a crystalline structure, and the bonds between the atoms are such that the electrons in the outer shell are not bound, but are free to roam within the lattice. This explains their high electrical conductivity and good thermal conductivity. Metals are seldom used in pure form, because their qualities are enhanced by being alloyed with other substances. They’re grouped together as either ferrous (ie, they contain iron) or non-ferrous.

The strength of the finished parts depends to some extent on whether the parts have been cast, forged, or machined from a steel solid, and the various alloys are tailored to have the qualities needed for the relevant manufacturing process. The casting process involves pouring liquid metal into a mould, allowing it to set, but forging utilizes two or more dies that force red-hot solid material into the shape required.

Ferrous Metals

This group includes all the alloys that contain a high percentage of iron ore. They differ from one another mainly in the amount of carbon present. Most of these are refined from pig iron, which is obtained from smelting iron ore with coke (dehydrated carbon) and limestone (calcium carbonate).

Wrought Iron contains less than 0.1 per cent carbon and between 1.0 and 3.0 per cent finely divided slag (a mix of metal oxides) distributed throughout the material. It has a high resistance to corrosion, and in the past was used for water pipes and other products that were used in a corrosive atmosphere. It is easy to weld, very ductile and forms a good outer surface for protective coatings to adhere to. Most cast iron alloys are usually cast into a shape, hence the name. These days the term cast iron usually refers to grey cast iron, so named because fractures show a grey appearance. It contains between 2.1 and 4.0 per cent carbon, and 1.0 to 3.0 per cent silicon. It is fairly brittle, but has a low melting point, makes superb castings, and has excellent machining capabilities and wear resistance.

Steel contains at least 0.3 per cent carbon, and very small percentages of other elements. Most steels contain no slag, and are classified according to their carbon content. The amount of carbon added will increase the hardness and strength of the steel. There are so many different steel alloys so we will only mention the more important groups:

Plain-carbon steels consist mainly of iron and carbon, and are classified as low carbon (0 to 0.25 per cent C), medium-carbon (0.25 to o.55 per cent C) and high-carbon (above 0.55 per cent C). These steels vary mainly in hardness and therefore in tensile strength.

‘Carbon Increases the Strength of Steel’

Nickel steels contain between 5.0 and 35 per cent nickel. They offer increased resistance to low temperature impact, increased magnetic properties, and resistance to corrosion at high temp. Nickel chromium steels are tough and ductile and exhibit high wear and corrosion resistance. Molybdenum steels are easy to harden and stay hard at high temp. By adding molybdenum to low-carbon steel increases the tensile strength. Chromium steels have increased core toughness and wear resistance. Triple-alloy steels contain nickel, chromium and molybdenum. They offer a high strength-to-weight ratio and good corrosion resistance.

Non-Ferrous Metals

1. Aluminium

The most important of these is aluminium. It has sporadically been used for major engine components since the dawn of motoring. Its major attraction for design engineers is the fact that that the same part is two thirds lighter if made from aluminium instead of steel, but unfortunately it is also a lot less stiff by the same amount, and a lot softer. This means that any change from steel to aluminium  can only be done after a complete redesign of the part. In practice, this means that some of the weight advantage of aluminium is inevitably lost when used in high stress situations. Aluminium alloys have improved beyond recognition in the last four decades. Aluminium’s great come back started in the 1960s, when aluminium cylinder heads started to replace traditional cast iron heads. Aluminium is often alloyed with copper, zinc, manganese, silicon or magnesium. Interestingly enough these alloys are not corrosion resistant as the pure metal. In the latter form aluminium tends to form a clear protective layer of oxide. On the other hand when aluminium alloy is in electrical contact with some other metals such as stainless steel, galvanic corrosion sets in quickly. Corrosion is a problem inside a water-cooled engine with an aluminium head and a cast iron block. One of the solutions is to use a cylinder head gasket fitted with stainless steel rings around the bore to prevent contact between these metals. American vehicles use on average about 157kg of aluminium, compared with 110kg a decade ago, and the metal is used to an even greater extent in Asia and Europe. In fact the only barrier to increased utilization of aluminium is the metal fluctuating price on world markets.

2. Magnesium

Most people are familiar with magnesium because “mag” wheels as well as beverage cans are made from such alloys. It is the third-most commonly used structural metal after steel and aluminium, and has two-thirds the density of aluminium, and shares with the latter metal the propensity to develop a thin layer of oxide that prevents against further tarnishing. From there conception VW Beetles and Porches were designed with magnesium-alloy cylinder heads and block crankcase units. At the time the alloy was relatively inexpensive, and its lightweight was needed to curb the rear end mass would have on stability and handling. When the Beetle died so did the use of magnesium alloy. During the Beetles peak production years the Volkswagen Company used 50% of all magnesium consumed in Germany, amounting to nearly 42,000 tons a year.

Magnesium is highly flammable in powder form, and even from small chips arising from machining can catch alight. The resulting flame cannot be extinguished with water or carbon dioxide: sand should be used instead. Currently, most European companies use magnesium under the trade name Electron, for items such as transmission casings, intake manifolds and cylinder head covers.

3. Titanium

This metal is names after the Titans of Greek mythology, and has been called a space age material because it has the highest strength-to-weight ratio of any metal. It is as strong as some steel alloys, but weighs 45% less in pure form, and only slightly more as an alloy. It is also highly corrosion resistant.

Engine Parts

The materials used for various engine parts are:

1. Cylinder Bock / Crankcases

During much of the pre-1930 era it was common to build up the engine using a two-piece cylinder block. The part housing the cylinders was cast iron, either in unit with or separate from, the cylinder head. The lower part housing the crankcase was an aliminium casting, and so was the sump. For many years cast iron has been used for engine blocks, but at present it is considered too heavy for petrol units, but is still the material of choice for most diesel engine blocks. Modern petrol engine cylinder blocks are cast using aliminium because the reduction in mass is desirable. The recent BMW straight-six engine gained a two-piece magnesium/aluminium cylinder block to reduce mass on the front wheels by nearly 14kg. This helps to promote a near 50:50 weight distribution.

The cylinder bores are either loose cast iron sleeves or the bare aluminium treated with a coating or chrome spots are introduced using a special process. Failing to do this would result in excessive wear, as aluminium is not wear-resistant.

 2. Cylinder Heads

For many years cylinder heads were made from cast iron and still is used for most diesel engines. However, in the 60’s aluminium took over, initially for it’s superior heat conductive properties, but these days also to reduce engine mass.

3. Pistons

Until the early 1920’s most engines were fitted with cast iron pistons, but these were later replaced by aluminium items. The latter offer a reduction in reciprocating mass as well as superior heat conducting properties. Most production pistons are cast from alloys having a high silicon content, but racing pistons are usually forged. Forging is a superior but also a more costly process, and a stronger alloy can be used.

 4. Connecting Rods

High strength steel is used for most ‘rods, although a special aluminium alloy was tried in the past but doesn’t appear to have been very successful. Modern high performance engines tend to use titanium alloy because of its superior strengths.

5. Crankshaft

Until the early 1930’s most cranks were forged from high strength steel, but Ford started the fashion for casting cranks from a special mix of cast steel alloy. This saved time and money, and the process is used extensively these days. High performance crankshafts are either forged from special alloys if a large quantity is needed, or machined from billet if only a few are required.

6. Sump

Cast aliminium is used on expensive engines, but on most mass-produced units, pressed mild steel is the most inexpensive choice.

7. Manifolds

Exhaust manifolds are usually iron castings, but intake manifolds are either cast iron or aliminium castings. Plastic intake manifolds are also becoming popular with vehicle manufacturers.

 BUSHED

Suspensions come in all shapes, sizes and configurations. In order to set up the suspension in the correct way, the frame or the sub-frame, should be separated from the vehicle. The idea is to simply allow removal of the body mount ‘biscuits’ found on many vintage machines. Over time these components become weak from abuse at the hands of power crazed maniacs. These actions take their toll on the particular parts concerned. In short they are almost always worn out. The idea is to take the squirm out of these mounts.

In an effort to make the sub-frame / body package more integral, we strongly recommend that the rubber/steel body mounts be replaced with a set of aluminum bushings that can be machined from scratch.

The original mounts are a compromise between ride, road noise and handling. When pushed to the limit, the rubber mounts deflect. While deflecting or moving under load, such as in extreme accelerating, cornering in a highly modified muscle car or the seriousness of dragster racing x-treme acceleration forces, a considerable amount of energy is wasted compressing or stretching the body mount. The suspension has to work harder to keep up with the deflections of centrifugal forces etc and starting line capabilities are compromised.

The ride characteristics of such a solidly bushed system are noticeably harsher and road noise is transmitted rather quickly to the cockpit, but with a full house V8 mother of a motor under the bonnet, such problems could be considered trivial.

• WISHBONE ANIMATED

In most muscle car applications, there is no need to replace standard factory control arms with aftermarket equipment. Most original manufacturer designs are considered almost perfect, are considered to be lightweight, possess the correct geometry and are readily available at scrapyards, salvageyards and vehicle dismantler yards. If you can’t find them call “PART FIND” – “LOOKING4SPARES”  on  0861 77 77 22  (call centre).

Clean the control arms with degreaser and inspect them thoroughly for any visible cracks any sight damage that could have been sustained on its journies. If you suspect the control arm for any defect, replace it immediately. The original ball joints should also be sussed out carefully. If you suspect them for any ware or damage, you can replace them with TRW or similar quality aftermarket components.

During the time of the rebuild, examine all the control arm bushings and replace them with quality bushings. It must be pointed out that bushings must be replaced by a wheel alignment shop prior to painting any component on the car or truck. (This is, so not to scratch or chip the new paint). Simply take the time to mask off the various non-painted areas and blow the ‘wishbone’ control arm.

• TIGHTLY COILED

There is one area where drag racing technology becomes an asset for hi-performance street performance is the front coil springs. Marked ‘for drag race use only’, aftermarket springs such as the Moroso assemblies can find a home in specialized, limited use street applications. These springs feature added coils, a longer overall length and slightly thinner than stock diameter spring. This allows the springs to store energy within themselves. While at a stand still, the car remains level (or in some cases, has a slightly forward rake), but when the throttle is mashed to the floorboard, the nose of the car will rise rapidly. While accelerating through the transmission gears, the springs settle down rapidly, hanging down the nose of the race car to a more aero dynamic profile.   

Remember the ‘lightweight’ springs allow the nose of the car to rise rapidly. As a result, weight is quickly transferred to the rear of the car where it will do the most good in terms of drag strip runs. These springs are essential to shaving a tenth off quarter mile times.

• WEIGHT WATCHERS

There are two distinct methods to gain performance and that boils down to, ‘add more horsepower’ or begin removing some weight off the beast. Sometimes adding horsepower is a whole lot easier than having to find ways of discarding weight from the vehicle, especially if you are dealing with a made-in-Detroit chunk-o-iron. So just how much can be gained by shedding kilos-and-pounds? For the pure sake of comparison, let’s assume  the cars a relatively healthy streetcar. Normally aspirated engined power the jam runs 11.08s at 111 mph. The car is a typical streetcar so it’s no flyweight and tips the Toledo’s at 3850 pounds with you in it.  A quick power speed calculation reveals that the engine produces approximately 405 hp (net), which in turn, produces the 11-second passes.

If you can shed enough weight off the car /truck, like loosing between 300 to 350 pounds, how much faster will it be?  Using the same HP numbers, but at a weight of 3450 pounds, the elimination times crumble to an 11.44 at a speed of 116+ mph.  To match that elimination time number by adding the horses to the mill, you’ll have to find at least 40 to 50 more ponies.  In some cases, it really isn’t possible – especially if the car is already on the ragged edge of “streetability.”
Naturally, the parts swap or component removal process on a single purpose drag race car is a relatively easy task.  On the other hand, a street/strip car is another whole ball game altogether.  Drag strip racecars don’t need the normal every day car charging systems – but streetcars do.  Most racecars don’t need steel hefty bumpers – street strip cars do.  Racecars don’t need the passenger seat – road cars do.  The list goes on and on and on….  But there are more clever ways to remove the weight from any intended race or street strip car without sacrificing a street racecar. Living in Africa always has its advantages and in this place we can get away with almost anything. Here’s how the numbers slowly stack up:

FIBERGLASS BONNET – Total Reduction:  45+ Pounds
FIBREGLASS FRONT BUMPER – Total Reduction: 15+ Pounds
ALUMINUM CYLINDER HEADS – Total Reduction:  75+ Pounds
ALUMINUM INTAKE MANIFOLD – Total Reduction:  20+ Pounds
ALUMINUM WATER PUMP – Total Reduction:  10+ Pounds
ALUMINUM RADIATORS – Total Reduction:  25+ Pounds
HEATER DELETE SYSTEM – Total Reduction:  20+ Pound
PAINT & BODY – Total Reduction 25+ Pounds
UNDERCOATING – Total Reduction:  25+ Pounds
FRONT STABILIZER BAR ASSEMBLY – Total Reduction:  15+ Pounds
SPARE TYRE & JACK – Total Reduction: 25+ Pounds

Total Weight Reduction: 300+ Pounds

There is one warning to the writing noted above and that is the “light is right” situation.  Certain cars happen to work better with some added luggage in the boot of the car.  Some cars/trucks work better with 50, 100 or more pounds of ballast on the back or in the boot.  This is a process of elimination of experimentation – try your car without ballast, add some weight and keep on adding the weight until the car slows down. You be the judge.

• Conversions Chart

When it comes to building horsepower one thing every racer has to use at one stage or other is a conversion chart at some time or other.

Multiply           x     by             =     to get        x     by            =     to get

Horsepower     x     0.746        =     kilowatts     x     1.34         =     horsepower

Inches             x     25.4         =     mm            x     0.03937    =     inches

Inches             x     2.54         =     cm             x     0.3937      =     inches

Miles                x     1.6093     =     km             x     0.6214      =     miles

Foot lbs            x     1.3558     =     (Nm)          x     0.7376      =     foot lbs

Mp/h                x     1.6093     =     km/h          x     0.6214      =     Mp/h

degree C           x     0.556     (F-32)                 x     degree F    =     (1.8C) +32

Cubic Centimetres
¶r2      x      distance      =      volume x cylinders

• FAITHFUL TEMPERATURES

Cooling an engine is like walking a tightrope.  If the temperature is not kept in check, the radiator will boil over.  If the temperature is too low, the engine will not produce peak horsepower, as you would expect!

Can horsepower numbers be found in cooling down the engine?  Oh yes it can!  Temperatures commonly run in street applications are too low for the production of peak horsepower.  As a rule of thumb, the coolant temperature should be in a range between 200-210°F, while the internal pressure should be in the area of 20 lbs.  If the engine is run at a lower temperature (lets assume your temperature guage hovers around 175-180°F), you are wasting approximately two to three percent in the horsepower department.

It should be noted that a 21-pound pressure cap would automatically raise the boiling point of pure water from 212°F to 260°F.  The addition of a 50-percent solution of aftermarket “coolant” (almost always ethylene glycol or more commonly, “anti-freeze”) will then raise the boiling point to approximately 275°F.  Obviously, an internal combustion engine operating at these temperature extremes is out of the question with current technology.  Just consider the added temperature capacity as a “cushion”. All these points taken into account set you up in the rule of thumb division.

• ENGINE PULLEY POWERS

Perhaps easier than swapping impellers, changing pulley sizes gives you the opportunity to “tune” the cooling system for your application.  When the crank pulley is reduced in size, the actual speed of the water pump can be decreased from 25 to 50%, which in turn frees up a significant amount of power from the engine.  Obviously, a larger diameter water pump pulley will accomplish the same goal.

If you decide to play with pulleys (and we highly recommend that you do), there are several different options open to you.  Moroso Performance offers a wide array of cast, machined aluminum pulleys for a number of different applications.  By mixing and matching components, you can tailor the water pump speed to your application.  Take your pick in regards to methods of reducing the water pump speed, they all work, but playing with pulleys isn’t the easiest and most productive way out.

What about “deep groove pulleys?”  Deep groove pulleys are just that, pulleys with deeper than normal grooves.  Their sole purpose is to keep the belts affixed at high rpm and aside from correct pulley alignment, they are the only salvation when it comes to tossed belts following a high rpm blast down the strip with your street rod.  Most of the original equipment had the foresight to install this form of pulley on their hi-performance models during the heyday of the muscle ‘super’ car and because of this, the parts are “somewhat” available. It always takes some doing to ‘find’ the precise parts when looking4spares. You must use every avenue possible when trying to locate these out of date and elusive parts. Somebody, somewhere will have exactly what you are looking for when looking4spares. Keep on trying and never give up.

• AUTO COOL

The thermostat’s purpose is to control the cooling down and heating up of any engine.  It is an essential feature and should be considered as the cooling system’s ‘on and off’ switch.  The purpose is simple-it allows the engine to warm up quickly (by blocking the flow of coolant through the radiator), thus discouraging the buildup of sludge and internal acids.  When the thermostat is removed, the coolant circulation is constant and in some cases, way too fast to provide adequate cooling. In addition, the engine’s warm up time is increased if the thermostat is removed.  What this accomplishes is simply escalated engine wear.  The by-products of combustion condense on the cylinder walls and as a result, the chances of wear are multiplied. Engines are designed to run between certain varying temperatures to reduce wear. The powerplant will suffer the most wear during the cold start up period, (especially in winter), that is why the thermostat plays such an important role and should never be removed from a streetcar.

In the event that warm-ups are not critical to your application (i.e.: a warm weather street/strip car), you might consider the use of a water outlet restrictor plate.  These components available from Moroso) replace the thermostat in the engine water neck.  They are flat “discs” fitted with either a 5/8-icnh, ¾-inch or 1 – inch diameter hole.  Designed to reduce the coolant outlet flow from the engine, these components give the coolant an opportunity to absorb internal engine heat when compared to a non-thermostat example).  As expected, they do not provide any opening or closing action such as a thermostat (and in certain applications this may prove superior), but they do offer a method of regulating coolant flow.

If overheating in anyway is being suspected, remove the thermostat from it’s housing and place it in a kettle or pot of water on a stove keeping your eye on it as the water heats up and approaches near boiling point. If it hasn’t started opening or doesn’t open then your problem has been identified. Thermostats have been known to cause all sorts of failures and frustrations. Replace them with ‘quality’ products.

• HORSE & HOSE POWER

Hoses are hoses.  You just bolt them on and have confidence in their design integrity.  Unfortunately, it isn’t that simple, especially when a high-performance vehicle enters the equation.  While braided lines make up the upper end of the spectrum, the cost seldom justifies the installation, particularly since the pressures found in cooling systems is not that great. The ‘correct” radiator hoses to use are the non-ribbed formed equipment that is commonly associated with OEM suppliers.

Many of these rad hoses are manufactured by the original vendors and as a result, the quality and fit is right on target.
When it comes to the hose clamps, the best setup we have examined is the line of “T-handled” clamps sold by Moroso.  These clamps feature a special “handle” that is complete with a 3/8-inch hex head and a simple screwdriver slot.  You can use either the T-handle, the hex or the screwdriver slot to tighten down the clamp.  T-handles are by far the better products and you can gain a better ‘feel’ when tightening the hose clamp.

Using the screwdriver type clamps is more than often cumbersome and tightening procedures are hard to ‘guage’ on how much tension is being needed or being applied to the clamp, (often ending up in an over-tightened or stripped clamp).

While seemingly insignificant, T-handled clamps can prove to be a marvelous addition if the car is drag raced (even minimally). The quick release feature of the clamps allows the radiator hoses to be removed quickly and instantly, providing immediate access to the engine for between rounds cooling.

If you have ever experienced a “missing” lower rad hose, you might consider double clamping the assembly.  An inexpensive set of stainless steel, worm gear hoses from Earl’s will solve the problem-especially if a pair of clamps are used on each end of the hose.  Credit this tip to the NASCAR crowd.  They take every precaution when it comes to reliability and hose clamps are no exception! Always keep a set of spare hoses in the trailer, just in case.

• FANBELT TENSIONS

Belts should be checked periodically for tension.  Low tension creates belt slippage, which in turn wears out the belt, creates heating problems and allows the battery to run down for obvious reasons.  On the other hand, excessive tension is hard on water bearings and in the case of certain aluminum pumps; it can destroy them in no time.

If you don’t have a belt tension guage in your possession, you can use this “old-timers method” of determining correct tension:  Select the longest unsupported span of belt.  Push on the belt with your thumb.  If it moves more that a quarter-inch its too loose.  If it doesn’t move, the belt is too tight.  You will get the feel and if it’s too loose you should hear it slipping, screaming for help as you accelerate. It’s as simple as that!

POWER TRAIN

• GEARED FOR RATIO

Selecting the correct rear axle ratio for your car is probably the most important decision you’ll have to make.  In this arena you can vary the amount of torque created on the back wheels (also depending in tyre size diameter), or make for the longer hauls giving a bit more top end speed. Let’s look at a pair of different street cars, one with the rear fenders stuffed full of Mickey Thompson Sportsman tyres and the other with wide, but short 17-inch radials For the sake of comparison, lets assume that both cars are powered by the above engine and are hooked up to an automatic transmission.  Both have 3.00:1 gears in the third member.  The following are the basic tire and gear ratio specs:

Corner Burner                           Pro Street
Axle Ratio                     3.00:1                                     3.00:1
Tire Diameter                26.00 inch                               33.50 inch
Final Drive Ratio             1.00:1                                     1.00:1

As you can see from the above figures, there is a huge difference in the speeds of cars at a given RPM level. The only mechanical difference between the pair is the height (or diameter) of the rear wheels. Obviously, the 3.00:1 gear isn’t close to being optimum for the pro street application. And if your corner burner has an overdrive, it too needs more gear. Given this set of circumstances, it would seem appropriate to stiffen up the gear in our paper Pro Streeter. An educated guess would be a gear in the range 4.10:1 ratio. Using the same engine speed 33.5 inch rear tyre height (diameter), here’s the final cruising speed calculation with the new ring-and-pinion gears:

As you can see, it’s certainly better than the earlier situation where the engine combination was barely off idle at a typical ‘highway legal’ cruise speed. Naturally, if the Pro Street vehicle had an overdrive automatic gearbox, the ring-and-pinion gear choice could be much stiffer, (a 5.38 gear coupled with the .70:1 overdrive and 33.5 inch tall tyres works out to a cruise speed of approximately 66 mph hour). Finding the best combination will be the deciding factor and this always boils down to one thing – ‘horsepower’. If you don’t have the ponies, your next best bet is to find the most compatible gear-tyre-ratio.

• CLEAN N’ POLISH

Before commencing work on the rear axle housing, try this on for size: An excellent method for cleaning the housing is to have it dipped in your local chrome shops cleaning vat. All lubricant is removed making it easier to work on. If a tank is out of the question get down and dirty. A high pressure hose, lots of Prepsol degreaser and hot water and an array of brushes should get the job done.

• DA’  COCONUT

When welding the axle housing tubes to the coconut (centre section of the diff housing), grind down the area you are going to weld on first, and then spot-weld the factory tubes to the coconut via the heliarc weld. Naturally the work can be accomplished with another form of welder, but a heliarc welder proves much cleaner (no weld splatter or ‘spitting’) and offers better penetration than other formats when properly accomplished. It’s more labour intensive but welds are superior. Weld in an open-air environment and keep your eyes protected at all time by using quality equipment. I cannot recommend the use of a dust mask more than this. Don’t skimp here; you only have one life – take care.

• SWEATING OUT

In stock form, many axle tubes are attached to the coconut with a couple of spot welds per axle tube. In most cases these spot welds are not sound and in most cases pinholes in the welds are clear. This really doesn’t compromise strength in a housing that has been totally welded to the coconut, but there is still one major problem: The factory welds often seep lubricant. Because of this, more than one axle hosing has seen major seal, gasket and drain plug work, only to find the leak or sweat was a factory fault weld pinhole). The solution is simple but difficult and time consuming to accomplish. To fix the problem once and for all, grind off all the factory welds, (using your mask and eye protection). Next, using a plug weld or ‘rosette’ process, replace the factory weld with a bead of heliarc weld. It’s a messy process, but the result is a clean, leak-free, differential housing.

• SPRING PERCHES

Factory spring perches are strong enough for mild street use, but they can crack and work loose under severe loads imposed by high-performance engines and all-out drag racing applications. In order to brace-up the spring perches: Cut out small plates of metal (gussets) that will eventually brace the perch on both sides of the spring carrier. The housing is cleaned and the plates are cut with a V-shape and edges chamfered to allow for total weld penetration. After the plates are tacked into place, weld them. With the plates installed, the spring perch is now fortified for fore and aft movement to deal with the twisting and squirming that will be experienced when hammering down on the button. With the job now done you can tackle your next project.

• THROWING OUT THE CAPS

The rear bearing caps found on axles such as on the Chevy twelve bolt main and Dana 60 are cast iron and aren’t renown for their strength as would be found with a Ford 9-inch rear. The torque forces on the engine will try to push the carrier out the back of the housing – placing additional strain on the drivers side bearing cap. The shear forces of toque twisting and jerking have their impact.

As the car accelerates, the ring gear tries to climb out of the diff case or housing. To solve this problem aftermarket machined steel bearing caps can be fitted. In order to custom fit the steel bearing cap to the housing, the bottom of the cap is milled. (Align boring of the housing is not required). In most cases, installation of the cap is completed via a set of extra-long Grade 8 Allen head cap screws.

• SEVERE DIFF DUTY

The heavy duty 12-bolt diff features a thicker-webbed, reinforced flange on the diff casing, which reduces ring gear deflection under the x-treme loads experienced in drag racing. Spider gears are machined from high grade forged tool steel (approx. 40% stronger than the standard Chevy produced packages). Four more friction discs were included (A total of 22 discs), which allows for more even-distribution of shock loads to the side gears. The added friction gears help improve the torque split ratio that occurs in differentials.

Spring plate size, as well as springs them selves, are substantially larger than in the stock Chevy diff. The mod provides for an even bias ratio between the rear wheels and the outcome is improved on strait line traction, without breaking out and loosing valuable time. Most importantly, the U.S Gear units are designed for use with huge 33-spline axles, a huge improvement over the factory produced 30-spline axles. Although custom axles are required for this U.S. Gear-posi traction assembly, it is virtually bullet proof. Finally the U.S Gear-posi traction packages are designed for use with ring and pinions ranging from 4.10:1  to  6.14:1 and more ratios’s to come as we were informed.

• ALL AROUND THEY GOES

According to the guys at Summers Bro’s, axles have to endure two kinds of loads, tortional loads which are the twisting loads and bending loads which are the loads that try to bend anything possible if not retained and maintained, so to speak. The larger the diameter of the axle, the greater the ability it has to endure and withstand these violent forces. If the diameter of the axle is doubled from 1.0 inch to 2.0 inches, the tortional strength is increased ‘eight’ times.

Naturally it’s almost impossible to double the diameter of an axle, but in many cases it’s possible to increase both the size of the axle and the number of splines machined into the axle shaft. There is only one aim and that’s to improve strength and to ‘handle’ what is dished out in the horsepower to tarmac department. A good example of this is a 12 bolt rear main equipped with U.S Gear posi-traction unit, the axle spline count increases from 30 splines to 33 spline count, increasing strength by 32% over a stock axle spline configuration. These are essential steps when bidding for more horsepower that must be adhered to, and if ignored the fun comes to an abrupt end.

• “C”- CLIP SIDESHAFT

Not only are the factory C-clips a pain in the but; they’re also illegal in most drag race classes. In a stock application the splined end of an axle is machined with a special small end diameter groove to accept a C-clip. This groove not only weakens the axle by a significant margin but it can prove troublesome to remove and replace, (no matter what anyone says). With a C-clip system in place, the axle is retained from the inside rather than the outside. If the axle breaks anywhere the wheel/tyre combo can and (will), quickly depart from the vehicle. The use of a C-clip eliminator kit makes it possible to remove the axles from the vehicle without draining the diff lubricant. Finally, the old drill of grinding the ring gear teeth to clear the spider gear shaft is simply not required with the C-clip eliminator kit.

• STUDDED AXLES

Original equipment manufacturers, 7/16-inch wheel stud simply isn’t adequate enough for any vehicle that will be powered down the drag strip or see even any mild bracket competition. All modified cars or trucks should have the wheel studs replaced with minimum half inch studs. Heavy duty studs are fashioned from grade 8 materials and are threaded all the way to the head, (more like a fully threaded bolt), and can be fully engaged into the backside of the axle flange. If your street racer or full- blown drag car or truck that has a lot of heat under the bonnet, can benefit from the use of ‘axle studs’.

In most cases, these axles have massive studs that measure a massive 11/16 inch in O.D. Drive studs are designed to fit the holes in thick centre aluminum race type wheels like Cragar Race Rims. These studs feature a colossal ¾-inch axle thread, (the part of the stud that screws into the axle). Without these modifications to the drive shaft axles, your ride will become a danger to everyone especially if used for public road use. Every turn will weaken inferior axle configurations and eventually they will break off. Take the initiative to protect yourself and others from certain calamity!

Most custom axle manufacturers offer several choices for wheel bolt circle patterns. According to the pro’s, pick the largest possible bolt circle pattern that fits the application. When the pattern size is increased the unit load per stud is reduced. The larger the bolt pattern diameter the, the lower the force imposed on the stud. It is often possible (and relatively easy) to re-drill the brake drums so that axles with a larger-than stock bolt pattern can be used. Obviously, if stock wheels are planned for your ride, this method of increasing the bolt pattern circle is limited. Keep in mind that the Chevrolet pattern of 4-3/4-inches is larger than stock FoMoCo or Mopar passenger car patterns, (and the conventional truck pattern of 5x5.0 inches is larger still). Because of this, the unit load on each stud is less.

• OVER THE SEAS IMPORTS

Locating quality bearings can be a bit of a nightmare on a local level and can take frustration levels to the maximum. Companies such as Richmond Gear, G&G Specialties and Mark William Enterprises identified the problem and introduced ‘ring-and-pinion’ kits to the market place, throughout the world. These installation kits feature ‘top quality’, ‘made in the States’ Timken Bearings throughout. High grade 8 bolts (ARP models in the M-W kit) for the ring gear, a crush sleeve, a new pinion seal, thread locking compound, gear marking compound and brush, a cover gasket and a cross section of pinion and carrier shims are included in the ring-and-pinion kits.

If you are “looking4spares”, “Part Find” will assist you by finding the new spares or used parts. Simply fill in the parts-request-form on our home page and ‘submit’ your order.  Your parts request will be circulated to all leading “parts dealers” and “scrap yards” in Southern Africa. You deal directly with the parts supplier – No Middleman -