*** Wanted*** SEAC or Wedge rear suspension part.

[cantus]

I am looking for a pair of rear suspension rods for my SEAC. I do not know the exact name for these bars.
These are the rods mounted parallel with the doorsills and they are connected from the rear suspension to the chassis. See picture , where you can see a small part of the rods right down in the middle.
[pic]http://ph.uncle-dave.co.uk/upload/images/rod.jpg[/pic]

The rods are straight, adjustable and do have a rubber bush on both ends. Lenght is aprox 55 cm.

please advise,

William

[JR]

jchase said:

TVR call them trailing links

Richard Thorpe used to sell upgraded ones; he may still do.

[cantus]

Thank JR

Do you have an e-mail adress of Richard Thorpe ?

gr
William

[GreenV8S]

Try www.rtracing.co.uk/

[jchase]

tvrcarparts told me they were looking into having some made when I asked for some earlier in the week.

-Jim

[rev-erend]

Might be worth talking with Steve Heath - perhaps it can be done with Racing Sperical rod ends and some rod..

[jchase]

Mine have one end as a rod-end. I'll gladly swap for a pair with rubber at both ends! -Jim

[cantus]

Good seconds hand ones will do also for me !
Whatever !! I want to drive it and give it it's first blast after 7 years owning it !

[adam quantrill]

The thing I find strange about this whole setup is that as the wheel goes up and down, doesn't this link pull it forwards? Surely this must twist the whole A frame slightly (or at least the rubber bushes) to toe in the wheel. Or is this the whole idea?

[jchase]

It's a bodge-up really, apparently added due to problems with rear end steering on the big torque 390 engines.

I think it is to do with the rear geometry twisting due to the axial load on the metalastic bushes. IMHO if you put solid bushes in the A arms (ala RT nylon upgrade) then this link arm should no longer be needed. But this introduces a whole set of new problems.

I'm gonna run mine without them for a while to see what is the effect - i suspect the car will be much more stable at white knuckle speeds on the autobahn, but a bit scarey on roundabouts at full throttle- we'll see.

-Jim

[JR]

jchase said:

a reasonable and interesting summary

In practice you need to match the spring rate and length to the bush stiffness.

[wedg1e]

adam quantrill said:

The thing I find strange about this whole setup is that as the wheel goes up and down, doesn't this link pull it forwards? Surely this must twist the whole A frame slightly (or at least the rubber bushes) to toe in the wheel. Or is this the whole idea?

Ah well.... I think the idea is that the huge front bush (to the chassis) can deflect/ distort so much that the wheel ISN'T pulled forward.

The thing that strikes me as most ridiculous about the whole trailing vs. A-frame debacle is that Lotus used exactly the same trailing setup on the Esprit (even down to the same t-arm bush), realised their mistake and simply added a top link. Had TVR done the same the Tas might well handle as well as an Esprit
Given that Ian Jones must have known about the Esprit cockup it seems odd he carried the glitch over...

[adam quantrill]

So are you saying that a trailing arm setup with a top link would be better than the A-frame? Presumably you'd need to change the driveshaft for a telescopic one.

[tallbloke]

Unless the top link and drive shaft were near enough forming a parallelogram...

[tallbloke]

wedg1e said:

Given that Ian Jones must have known about the Esprit cockup it seems odd he carried the glitch over...

Maybe he thought the heavier driveshaft would provide sufficient rigidity and vindicate the original esprit design?

[shpub]

rev-erend said:

Might be worth talking with Steve Heath - perhaps it can be done with Racing Sperical rod ends and some rod..

He's looking at it but needs to check the geometry and the strength required.

I've actually bent that rod with the welly from the 520 engine!

[shpub]

Oh and there are several different types with different diameter mounting bolts....

[wedg1e]

adam quantrill said:

So are you saying that a trailing arm setup with a top link would be better than the A-frame? Presumably you'd need to change the driveshaft for a telescopic one.

Well, maybe not perfect....

The Esprit doesn't have a telescopic shaft, though maybe the inboard CV joint has enough movement to compensate...
Then again, as Rog says perhaps it's a game of angles. The top link is very short compared to the bottom one.

[wedg1e]

tallbloke said:

wedg1e said: Given that Ian Jones must have known about the Esprit cockup it seems odd he carried the glitch over... Maybe he thought the heavier driveshaft would provide sufficient rigidity and vindicate the original esprit design?

Wasn't the larger driveshaft added rather later than the A-frame?

As for the Esprit, the story has it that the original prototype had no link between the tops of the rear suspension towers. The chassis guys said it would flex, Chapman said it would be OK. Sure enough it broke and the Esprit gained a (removable) 'chassis brace'.
Now when Ian Jones went to TVR and started on the Tasmin, the Esprit would still have been in S1 guise without the top link. Hence the Tas t/arm setup looks like the S1 Esprit's. Lotus realised it was crap and changed it late in the S2 (IIRC), by which time the Tas chassis would have been finalised and in early production.

The S3 Esprit had the top link (1981-ish?) and it's only a couple of years later that TVR 'started' having grief with the t/arm and produced the A-frame.
The Esprit is similarly-powered to a 2.8 Tasmin (c.160 bhp) so if Lotus realised it was problematic, one wonders if TVR also had difficulties sooner than the 390SE/ A-frame story appearing would suggest.

I know that the general line nowadays is 'the trailing arm is adequate for the 2.8' but really, is it? Most Tasmins I've been in have been squirmy, jittery crashy things... whereas even a rough Esprit will go round corners like it was on rails. Maybe with all new components it'd be OK...

And another thing: the forward trailing arm mounting bush is the same on both cars. Why then does it survive quite well on the Esprit - with the weight of the engine right above it! - yet the 'experts' recommend that you change the same bush on a Tasmin every year? If the answer is 'torque' then the problem was there from the outset...

Just to clarify: the Esprit has a trailing arm, top link on the axle line and bottom link to the rear of the chassis, effectively the same as the radius arm on a Tasmin.

[cantus]

Still looking !!!!
There must be someone with a spare set of Tie-bars ???