The Differential Torque Rods.

The diff torque rods are the most basic of mechanical devices , yet they perform a very important job of keeping the diff perfectly stabilised during acceleration and deceleration, if you want to see how important they are, just undo the nuts a few turns to loosen the rear bushes and then go for a quite drive around the block, you wont believe the thumping and vibrations a loose diff will create, (Well I don’t want you to do that, but you get what I mean) but if you have ever noticed some strange knocking noises from the rear drive train, you may have found the rubber bushes totally disintegrated due to oil rot from constant impregnation with gear oil leaking from the diff.

The fix for rotting rubber bushes is to replace the old bushes with new urethane bushes where a life span of more than thirty plus years is not unusual, some elan owners have the misguided view that worn original rubber bushes must be replaced with new rubber bushes, that theory is a fallacy, our S2 elan has only three rubber bushes, and they are the left & right hand side standard engine mounts, plus the rubber gear box mount, every other bush has been changed over to urethane, and the smoothness and NVH of the car has not changed much from the original.

Urethane is not affected by; grease, oil, chemicals, ozone, and it does not even seem to deteriorate with age, it is the ideal automotive bushing material, as long as the correct grade is chosen.

In the following photographs you will notice the changes from the original toque rods, bushes, and the way they are fixed to the chassis.

The RHS diff mounting lug, the spigot on the torque rod passes through the lug, and there are bushes either side, plus thrust washers and a nyloc nut.

The bush assembly installation. Notches in the rear washer provide clearance on the casting gussets, do not tighten if there is metal to metal contact.

The torque rod (RHS) bushes, washers, & 5/16″UNF nyloc nut. Urethane bushes are custom made from machined red urethane, which is simple to do in the lathe.

A view of the RHS diff torque rod. Both torque rods were fabricated from 3/4″Dia ERW 16g wall tubing, yes they are different to the standard parts, which I consider to be of a poor design, that is why we decided to modify and fabricate the items shown on this page.

This is how the forward end of the torque rod is secured to the lower outer edge of the chassis tray, a machined and threaded captive button is tack welded to the underside edge of the tray, the rod has a clear drilled lug bronze welded into the tube, the rod or tube is held with a 5/16″UNC cap screw, this set up has been in use since 1986, and has never given one ounce of trouble. The left hand torque tube is identical to the right hand rod.

When welding captive nuts to the chassis, it is much easier to carry out those mods when the car has been completely dismantled and the chassis is bare, making it easy to roll over or on to the side for easier welding.