Performance Classic Car Parts Performance Classic Car Parts

TIMKEN FORD (ENGLISH) AXLE OPTIONS


Click here for Salisbury Ford (Atlas) axle options


  Crown wheel & pinion
  Crown wheel & pinion
RATIOS
Ratios of 3.54, 3.77, 3.89, 3.90, 4.12, 4.44 were fitted to a variety of axles. In addition to these the Ford Motor Co. made some special ratios in the 1960s for competition use. These were 4.7, 4.85, 5.14, 5.28, 5.57, 5.66, 5.83, 6.16.

Usually we are able to rebuild diffs with either a good condition used or a new reproduction crown wheel and pinion although some ratios are not available.

  Aluminium casing
  Aluminium casing
ALUMINIUM CASING
First used in the MK 1 Lotus Cortina and since reproduced in a stronger type material. Weight saving over standard iron casing is 4.5kg (10 lbs).

LIMITED SLIP DIFF
There are two types of these, a plate type and a gear type. Both generate friction to provide the limited slip effect.



  Salisbury LSD
  Salisbury LSD
The friction plate type was first made in the 1960s and known as a Salisbury LSD.

It had a cast iron housing and end plate and because it is a relatively weak material the bearing spigot on the end plate often broke off causing major damage.

In more recent times this LSD has been reproduced with a steel housing and end plate for greater strength. It is also approved (homologated) for use in specific models used in classic car events under FIA rules.

LATER PLATE TYPE

  Later plate type LSD
  Later plate type LSD
A later type LSD is a completely different design. The lugs on the plates are located internally and the cones are located on internal splines, this eliminates wear on the housing. To create friction in the differential pressure is applied to the plates by a spring, the amount of pressure can be varied by changing the strength of the spring. The pressure applied is determined by the amount of torque required to turn a side gear while the other gear is held static. We can adjust the amount of torque required to rotate a side gear to any setting, generally the range is anywhere between 30-90 LBS/FT and is dependent on what the car is used for.

  Internal parts
  Internal parts
In addition to this the friction in the plates can be made to increase when the car is moving. This is achieved, depending on the design and make, by the planet gears or the planet gear shafts moving up ramps in the cones when the car is accelerating or decelerating. By varying the angle of the ramp the friction in the plates can be altered. As an example a ramp angle of 30 degrees will increase the friction in the plates more than an angle of 45 degrees. The characteristics of the LSD can be altered for the type use and driving style. For example a driver may prefer a setting that gives maximum friction in the LSD under acceleration but no extra friction when decelerating. This would require cones with 35 degree ramps for acceleration and 90 degrees for deceleration. Another preference could be cones with a ramp angle of 45 degrees on both acceleration and deceleration. There are many combinations of ramp angles, we can advise on choice according to type of use and specification of car.

Another feature is the bearing spigots are a larger diameter than standard and use different taper roller bearings. This combined with different side gears in the LSD enables halfshafts with stronger, larger diameter splines to be used.

A useful feature of the plate type LSD for competition use is if one rear wheel loses contact with the road, as often seen in a racing and rallying during fast cornering, the drive is still transmitted to the other rear wheel to keep cars speed going.

Today's classic cars often have engines with considerably more power and torque than originally fitted. This puts higher stresses into the axle and failure of the teeth on the two planet gears in the standard diff has become a common occurrence. Fitting an LSD eliminates this problem. When operating a plate type LSD can be noisy. If the car is turning a clonking sound is made, this is more apparent at low speed but is a normal characteristic.

GEAR TYPE
The gear type LSD comprises helical teeth gears fitted into pockets inside the housing. When there is a difference in the loaded rotational speed of the halfshafts, friction is created by forcing the gears against the wall of the pockets.

Both wheels need good contact with the road when cornering to generate friction in the LSD and increase traction. The differential is silent in operation.

  Broken shaft
  Broken shaft
HALFSHAFTS
The combination of metal fatigue and higher than original power and torque makes standard halfshaft failures a common problem.

Almost all breakages occur where the spline exits the side gears in the diff. Fitting new halfshafts with a higher specification material is an improvement, but better reliability can be achieved by fitting shafts that have a larger core diameter splined section.

There are two alternatives, one is the spline as used on Salisbury (Atlas) halfshafts that has 16 teeth and a 1.11mm larger core diameter than the standard 22 tooth spline. The other type is a ZF spline that has 18 teeth and a 2.99mm larger core diameter than standard.

Core diameter   22 teeth   16 teeth   18 teeth
Core diameter   22 teeth   16 teeth   18 teeth

  Special halfshafts
  Special halfshafts
The shafts are made separately from the wheel flange in a variety of lengths to suit different axle widths. The shafts with larger diameter splines can only be fitted if the LSD has the appropriate side gears fitted and the correct internal diameter on the bearing spigots.

The bearing on the standard halfshaft is a press fit with an additional press fit collar. It is not uncommon for cars in competition use to have the halfshafts pull off from the bearing and collar.This cannot happen with the special halfshafts because the bearing fits against a step in the halfshaft and is retained by the wheel flange.

In line with the best halfshaft designs used in big powerful competition classic cars of the 1960s, the wheel flange fits onto a spline on the halfshaft with the flange retained by a split tapered spacer and a large castle nut locked in place by a split pin. The shafts are supplied fitted with bearings, retaining plates and wheel studs to choice.

  Halfshaft bearings
  Halfshaft bearings
HALFSHAFT BEARINGS
We receive many halfshafts to have new bearings fitted.

Frequently these have been damaged, especially the bearing retaining plate, where attempts have been made to remove the old bearings. We have special tooling to remove and replace the bearings so no damage is done.

There are two types of bearing available for these halfshafts. There are those made to an unknown specification with no brand name marked on them and are sold in a variety of packaging. It is our experience, and that of many others, that these bearings have a life of as little as 2000 miles in a road car and one race on a track.

The alternative bearing are a quality item and have a brand marked on them. Our experience with these is that they are comparable to those fitted to the cars when they were new, but cost more.

To enable customers to easily send the halfshafts to us for new bearings to be fitted, we can supply a purpose made box for the shafts to fit into. Collection can be arranged if required.

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