Friday, 2 May 2014

Upgraded Engine Mounts

With the Southern Kit Car Club European road trip coming up it was time to give the car a check over and look for anything that might present reliability issues during the 1300+ miles.

One thing I've been keeping an eye on recently is the original Tiger engine mounts.  Other Avon owners have had issues with these failing and I suspected it was only a matter of time before mine gave me issues.  Upon closer inspection there did seem to be some metal fatigue setting in where the diagonal tubes meet horizontal plates.  I was not happy with this so decided now was the time to get on with fabricating a more robust replacement.

After jacking up the engine and resting it on some wooden joists I was able to remove the old engine mounts.  Straight away it was easy to see that in their natural rest position these had not been level with the top of the engine rubbers.  Instead they had been inclined and the tightening of the bolts had clamped them down onto the rubbers and had deformed the top of the rubbers over time.  This obviously meant that there was a constant force applied trying to tear the diagonal tubes from the horizontal plates, even before any twisting force is applied by an accelerating or decelerating engine.

With the original engine mounts fitted, the engine was not level.  So using the wood under the sump I raised the inlet side around 15mm to bring the bottom of the engine (sump) horizontal with the ground, when viewed from the front of the car.

Next I replicated the four flat plates.  This time out of 6mm steel instead of the previous 5mm.  For the diagonals I used 5mm thick 45mm box section.  This compares with the 1.5mm tube used previously.

Cutting these box sections to fit was a very difficult task.  Multiple compound angles and all work being undertaken with the engine in situ.  On the exhaust side I was having to work in between the small gaps between the exhaust headers - very difficult indeed.

In the end I got there.  Had them tack welded by Ashby Welding ready for a trial fit.  They fitted perfectly, with the horizontal plates resting on new rubbers, without any clamping and with absolutely no stress applied to the mounts or rubbers.  Back to the welders to have them fully welded up and here is the end result.  A very nice job done by the welder.

These have been painted up, fitted to the car and bungs inserted into the bolt holes to protect from water ingress.

Another long term to-do list job completed and hopefully another piece of reliability added to the car.


  1. Think you've done a fantastic job on the engine mounts. I too am worried as they seem very flimsy and my engine is not quite in line.
    Would you be able to get anymore made or be willing to share the templates to have another set made please?


  2. Upgraded engine mounts are definitely a good idea on a Tiger. Avoids any reliability issues.

    My engine is not in line with centre line of the car, I think this is quite normal. If I recall correctly, position is dictated by how close the starter motor bulge on the bell-housing can get to the chassis rail.

    Sorry, I made these manually and no easy way to replicate. I think you can buy (from ebay?) the plates that bolt to the engine. The plates that go on the rubber mounts are very straightforward. The time consuming part is getting the lenghs and angles of the tubes. It can also be very car specific, e.g. I've raised my engine to a very few millimietres from underneath the bonnet. Even shaved the oil filler cap handle down! This allows maximum road/sump clearance with the front wishbones properly set up to be parallel with the ground.

    Anyway, thanks for getting in touch and good luck with upgrading your mounts.