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Hi All,

My car is now (intentionally) on its side with the entire rear suspension components and axle removed. I'm standing there staring at it and have hit a wall as it were, the plan was to strengthen the mounting points where the trailing arms meet but i can see so many spot welded seams and potential for strengthening that i've gotten a bit overwhelmed by it all. Add the fact it's remarkably solid under there and has never had any welding, it seems a shame to go to town on it if that makes sense, in fact i don't really know what is necessary for the state of tune it's going to be running.

The question is, what would you guys do in my position?

Thankyou muchly,

Rob.

Rob,

You've been at this build for a long while. If it ain't broke, don't fix it - seems to come to mind when you mention that the power-plant wouldn't warrant it either. Just my two cents. You could always have a go later on during a winter lay up.

Depends if its for road use or rallying? For road use the standard arrangement is fine as long as it is rust free.
If its for serious competition might be worth talking to Troy O'Doherty who runs a very quick car in Australia and knows exactly which bits break and how to stop it. You can find him on Facebook as Triumph TR7V8 Rally Team

cheers guys,

The power plant is a 250+bhp V8, double what it left the factory with and along with the 225 /200lb springs, polybushes and uprated dampers i'm a little concened at the level of stress which is now being transmitted to the mounts. But, if they're good for that level of tune and can cope with the occasional track day then i'm happy to leave well alone. It has been a while, i got side tracked by installing that sprint engine, should of gone straight for the 8

Rob.

I had several cracks appear on the rear passenger bulkhead after installing my V8.

A touch of rear end steering under heavy uphill acceleration made me check out the rear mounting points. Thinning metal where the rear floor pan met the bulkhead had allowed the spot welded joints to move around. I had to butt and plug weld in several strips of metal. A few years later I had to weld in repair sections for the trailing arm mounting points due to rust taking hold. I didn't want the V8's torque making things worse so jumped on it as soon as I noticed it.

Adam

That's good enough for me. I'll box in the trailing arms, reinforce the mountings and fit a panhard rod. Thanks for the info, that's given me a lot to go on.

Rob.

Why not fit a watts linkage rather than a panhard rod? Use the SD1 bits and pieces - diff backplate and links. A quick look on ebay shows that Land Rover Discoverys have similar items - ebay number 321839987055.





A simple graphic:

Hi Jeff,

I did look at that. I drew a blank at the diff casing It appears they're pretty rare. The standard diff pan doesn't appear strong enough to modify either. What's your thoughts?

There is an increase of time and cost of the watts vs panhard, are the benefits worth it? Considering the use the car will get.

Sorry i just saw the pic, the benefits are obvious now. Doh!

Rob.

Whereas there is undoutably sideways motion with a panhard rod the diagram shows possibly the worst scenario.By making the rod as long as possible and mounting it horizontal at normal ride height the movement is lessened considerably.Just my observations after fitting one to my V8 MGB.Steve..

Steve's solution gets my vote
http://tr7beans.blogspot.nl/2013/03/new-back-axle-set-uo-for-t-kreng.html

What a coincidence I have just been looking at Watts linkages for TR7's. My car 'had' a Watts linkage but one of the towers broke and was partially cut off. Does anyone know where the linkage towers can be obtained from.

Sorry for jumping in on this thread!

The picture below shows the welds recommended by a local expert that is very familiar with strengthening the rear suspension for V8 conversion.


He did say that the welds shown in the first picture above would be sufficient, but I decided to also seam weld the floor pan as the interior was removed. The pictures below show the seam welding where the floor meets the rear bulkhead.

Those pictures are pure gold, thanks ever so much for posting. I've decided to go with the panhard rod because it offers the best bang for buck, even though the watts linkage does look the dogs! I really do appreciate all your help, i've now got a plan to work towards.

Re the brackets, can you copy the other side and fabricate one up? There are brackets for panhard rods on ebay, mostly listed for mk1&2 escorts, do they look similar to what you already have?

Thanks again,

Rob.

Given you have the rear suspension out and will have the fuel tank out as well, it is worth adding a few welds around the rear shock tower, as illustrated in the chalk marks on the picture below.


I recommend this as I have seen a track car where the towers had pulled away from the inner panel to which they were spot welded.

Just for interest, I first installed a panhard rod on my Morgan +4 when I was racing it. It made quite a good difference.

Later I changed to a watts linkage, when I got more serious.

It may have been because of the Morgans flexible chassis, [probably no worse than all TRs but the 7/8 range], but I could detect very little difference from the upgrade, & neither could the arbitrator of all such modifications, the stop watch.

Hasbeen