How Much More Wheel Travel Can I achieve?
Calculate Additional Wheel Travel Based on Axle Length
Proformance Ultra Narrow IFS and IRS DIfferentials
More wheel travel - Less CV Joint Angle - Less CV Failures
There are plenty of IFS (Independent Front Suspension) and IRS (Independent Rear Suspension) diffs on the market today, most of which use a conventional differential centre. Instead of an axle and some wheel bearings at the diff ends, the traditional live axle diff has been slightly modified by OEM's to accommodate Two (2) Male CV Flanges with Stub Shafts that slip into a female spline in the diff where the axles wold typically be located.
IFS differtials are typically sitting under an engine, and have the diff centred just a bit left or right of the engine sump to allow the tailshaft to pass by the motor.
The distance between the Flanges where the CV Joints are bolted is typically very wide and the Half Shaft Lengths are therefore very Short.
This picture says it all - Short Axles (Half Shafts) do not provide much wheel travel at all...
The main restriction is that for 60 or more years the traditional Differntial has remained unchanged in it's basic design. 99.9% of all differentials in vehicles today, including motorsport use a traditional carrier that tapers down in shape to accommodate small diameter tapered roller bearings.
Most IFS Differential Housings are either too wide to accommodate long half shafts or the internal comonents are not strong enough for motorsport applications.
Competitors are often forced to take a traditional Live Truck Axle and cut it up to convert ot to an IFS Diff. For years now, competitors have taken a traditional live axle and cut down the housings, machined some stub axles with CV Flanges and created their own narrow IFS Differential chasing longer half Shafts and more wheel travel.
In the past few years, companies have actually started to manufacture IFS cases that take traditional Truck Differential Components (Carriers, Bearings, Lockers) to provide strong competition IFS Differentials to Motorsport Competitors, but the distance between the CV Faces is still very long.
Some examples are shown below:
Using the Diff Centre from a Live Axle Truck Differential in a motorsport application by fitting it into a cut down or custom made housing or case still results in a very wide differential and short axles or half shafts.
Typically the distance between the CV Faces of an ULTRA4 IFS or IRS Diferential (Sipdertrax IFS/IRS, Currie IRS/IFS) is around 14-15 Inches (350mm)
Whether the Diff Centre is an Air Locker, Open Centre, No Spin, or Competition Spool No matter how much you cut and shorten the housing, the diff can never be narrower than the distance between the small carrier tapered bearings - period.
Front CV Joints can only travel up and down safely around 22 degrees whilst allowng for the required 25-35 degrees of steering angle. Short CV Half shafts do not provide a lot of wheel travel and in Off Road and Military Applicaitons, wheel travel is critical. Even a narow, custom made, cut down Spider Trac or Currie 9 inch or 10 Inch 14.5" Wide Differential does not allow for much wheel travel.
A lot of competitors go to great extremes to install additional slip joints, change the CV Joints to higher travel joints, but these modications only typically achieve an additional 1-2 inches (25-50mm) of wheel travel.
Competitors can at times end up with a driveshaft solution that is not correctly manufactured, with parts from different cars cut and modified with angle grinders and then welded together (See the welding in the above example) in an effort to acheve a bit more wheel travel, but only achieving more DNF's.
At Proformance, we have created a revolutionary new Differential that has Extra Large Tapered Roller Bearings that allow the CV Joints to be fitted up inside the Differential Ring Gear (Crown Wheel)
With the CV Joints mounted inside the Differential, the Faces of the CV Joints are only 40mm apart. That is 300-450mm (12 - 18 inches) narrower than the typical hand made IFS Differentials hand manufactured by competitors or professinaly manufactured units that are sold by both Spider Trax and Currie.
With the CV joints closer together, the axles are longer which provides more wheel travel. not a little bit, A LOT MORE WHEEL TRAVEL.
Lets to the maths:
Due to fitting the cv joints inside the diff carrier, we achieve an additional 6 inches of axle length "per Side" therefore we can assume "a" is 150mm (6 Inches)
To calculate additional wheel travel, we simply find "b" and multiple by 2 (travel both Up and Down)
Tan 22 x a = b (Tan 22 x 150 = 60.6)
Total Additional Wheel travel (2 x b) = 2 x 60.6mm = 121mm ( 4.75" )
When you consider that some vehicles only have 8 inches (200mm) travel out of the factory, an additional 4.75 inches wheel travel PER WHEEL is incredible.
Adding another 4.75" of wheel travel to an off road competition vehicle that already has 18 inches of travel would achieve 22.75 inches of travel using our Ultra Narrow Differentials.
Our Narrow Diffs can be used in IFS (Independent Front Suspesion) and IRS (Independent Rear Suspension) and are used in all forms of motorsport including Off Road Racing, ULTRA4 Rock Racing Rock Bouncing. The image below shows 33 inches of wheel travel whilst only applying 22 degrees of angle to the cv joints.
In addition to more wheel travel, longer axles allow competitors to run more ground clearance with less CV joint Angle. Asking the CV Jonts to work through less angle reduces the heat and stress on the CV Joints and axles, dramatically increasing reliability.
You may notice that the 4WD Trophy Truck pictured above has more wheel travel than available ground clearance, but the race team only uses a small percentage of the wheel travel, providing more wheel travel as other vehicles, whilst maintaining a very modest CV joint Working Angles and Heat Buildup.
For more information on how we can assist you to achieve more wheel travel and a stronger IFS or IRS setup on your vehiclce, contact us today.
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