Always Check Your Bottom!

says Chris Parkhurst.

Many decades ago, as a young aspiring Pilot Officer in the RAF, I was told by my flying instructor that it was essential to check the aircraft underside/bottom as part of your pre-flight checks. Today, I still undertake this procedure on my TC before undertaking a big trip to check that your nuts are tight and that there are no new oil leaks. This time, I gave particular attention to the rear axle supporting towers located above each spring and located by bolts and plates.

Guess what, I found a crack radiating from the base of the tower and across the tower, the entire base of the tower was cracked and fell apart. This is a common fault on T types with repairs often being required during the car’s youthful years! 

Failure to notice, will result in the axle breaking away from the spring and the wheel bring thrusted into the wheel arch, at speed you would probably leave the road – you would certainly stop!

To rectify this dangerous situation, you need to remove the whole brake drum and backplate so that fresh reinforcement can be undertaken by welding. Suitable plates are available from Paul Busby. Time must be spent lining up the axle so that the wheels run parallel to the chassis before welding. A belt and braces method to do now is to remove the 4 axle retaining bolts and welding a support bracket up the inside of the tower and located by the bolt at the lower end this will help spread the loads up the tower rather than rely on the base of the tower.

So always check your bottom for loose nuts and cracks with a fine toothcomb to prevent disasters on the road, I hope the photos explain my comments!

Ed’s note: Before showing you some of the photos that Chris sent, I thought it would be useful for the new and possibly less experienced TA/B/C owner, and for TD/TF owners who may not be familiar with the rear axle supporting towers on the TA/B/C (these are also referred to as support brackets, or spring hangers) to include one picture showing the general location and another showing a close up of a support tower in good condition.

Pic showing the location of the off-side supporting tower on the rear axle banjo casing.

Close up pic of the off-side supporting tower.

I initially had difficulty in understanding this pic. It shows the top spring plate which locates immediately below the base of the tower. What has happened is that part of the base of the tower has disintegrated and is left on the spring plate (Ed)

The below picture shows a plate in position to form the new base of the tower and ready to be welded to the side of the tower. The spring top plate can be seen located immediately below this plate and sitting on top of the leaf spring.

Pic shows completion of repair.

Ed’s note: Chris has recently followed up his article with the following:

To enable worry free motoring, I have now “invented” a belt and braces device that will give you peace of mind when speeding along the byways and highways of the world.

I obtained 2 conventional axle U bolts extended them by about 40mms and then drilled a 3mm plate which I then bolted to the underside of the rear spring and then bolted the U bolt through this plate. This will ensure that if the axle tower cracks and gives way, the newly installed U bolt will ensure that the axle remains safely in place. It also has the added bonus of helping to spread loads via a different route. The photo shows the U bolt in position.

Pic shows the “invention” described by Chris.

Ed’s further note: I suggest that a more common problem than the one experienced by Chris is that the holes in the base of the support tower, which take the four 31/4 x 5/16 inch HT bolts (you can also use M8 x 100mm bolts), were drilled too close to the edge by the Factory. To quote Eric Worpe:

“The holes for the spring fixing bolts are too near the edge of the bracket, and this allows deflection of the bracket around the holes when the whole assembly is stressed, particularly whilst braking hard. This results in fatigue cracks radiating out from the holes to the edge of the bracket.   The bracket needs to be reinforced, rather than just welded up, and if possible extended to give greater rigidity around the holes”.

The reinforcement is accomplished by welding in a strip of 1 inch wide by 1/8 mild steel around the inside bottom of the support tower. The strip needs to overlap the edge of the support tower by about 1/8 inch and be clamped in place before welding (see pic below).

Pic shows the strip now welded in.

Once welding has been completed, the bolt holes can be re-drilled.  A well-known weakness fixed!

One thought on “Always Check Your Bottom!

  1. Tim Parrott says:

    Prevention is better than cure. I have got doubler plates over the top of the base plate under the bolt heads. Paul Busby supplied these plates as well. They stop the bolts pulling apart laterally which is the cause of the cracks.

Comments are closed.