Hi Wedgies,

As you all know I love a nice Wedge & all my Wedgie mates, so please take all this in the constructive way it's intended.

I was having a look under Solitudes 350i the other day and started to get a proper understanding of what's going on with his rear suspension.

Pretty quickly I came to the conclusion that even with perfect new trailing arm bushes the design is never going to give proper axle location.

From a fundamental engineering perspective the design just doesn't seem right to me, there's simply way too much leverage on that big squishy bush & it really doesn't help that the arm itself is so efin long.

Just looking at the design & moving the system with a pry bar left me in absolutely no doubt...

Replacing that big old squishy doughnut with a properly bracketed bush would transform the the handling of these fantastic & very underrated cars ;-)

If you have even the slightest imbalance in the rear wheel, a worn/loose wheel bearing or a shagged UJ it's going to be massively amplified with the current design, not to mention the impact on handling such poor axle location will generate.

So I did a bit of PH research on the Tasmin trailing arm set up, and it came as no surprise to me that you clever Wedgies identified this design weakness years ago & have developed some sensible modifications to solve it.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

One guy even describes the bronze bush mod I came up with while discussing the system with Solitude, others seemed to have employed a rose joint when they raced these cars.

So my question is...

"Is there a bush & bracket kit available to solve the trailing arm design weaknesses?"

In my opinion every trailing link Tasmin out there would benefit massively from such a mod.

If a kit is not available perhaps one of you clever Wedgie boys could fab up a copy of their solution and make it available to the community?

Can anyone help?

I fitted these polyurethane bushes instead of the original rubbers: http://superflex.co.uk/proddetail.php?prod=SF111-1...

How is Gavlar these days?

Stu

Not a total solution but inexpensive and does help. Cheers Steve

What about a different (or perhaps complementary) approach - adding on "torque reaction arms" like wot's on the A frame, which connect the hub carrier end to the rear outrigger chassis tube.

Then you will have the convenience of being able to dismantle and put together the suspension relatively easily, plus it will behave itself better (especially with the crabbing you can sometimes get under hard acceleration.)

Essentially the design was lifted straight from the Lotus wedges (unsurprising as that was allegedly the last thing Ian Jones worked on before the TVR wedge): if you look under an early Esprit it's exactly the same. Lotus found the handling wanting so added a top link to the upper chassis rail. However this means that the driveshaft needs to change length as the wheel moves up and down so switched from UJs so CV joints.
In theory all that's needed for the TVR is to add a similar top link (the chassis is probably up to it) BUT the driveshafts are a bit trickier. You'd probably have to make or adapt the stub axles to allow mounting to CVs but retain the inboard UJ to couple to the Jag diff... on the face of it you could go for say a Sierra diff but then you'd need to sort outboard brakes...
Another option would be to modify the driveshafts to be Cardan shafts - where the shaft is in two pieces, one sliding inside, but splined to the other. That would allow the length change and retain the other standard components. So simple I'm surprised nobody's tried it

But all of this to to overlook the fact that a standard Tasmin is really not that ill-handling a car as long as all the bits are kept in good condition. I've been out in Chimaeras that felt very vague because the suspension had been neglected, so there's no point blaming everything on the design when the owners don't look after whatever is under there.

Hey Big Chimp Man, why dont you mosey on over to the classifieds and have a look at the wedges for sale, go on, you know you want to!!

Ill do you a good deal!!



Stu

I like them a lot!
The old rubber ones had some play on them and the car felt nervous when there were imperferctions on the road (even the painted road markings were easy to feel). Now the the ride is precise and smooth. Being a US-version the springs are not very hard, car feels very comfortable to drive. One might say: soft, but car steers where I want it to.
My car is standard Federal 280i model waiting for a fitting of a newly built 4 litre Cologne engine, so time will tell how well they cope the added power.

This summer I had two other TVR's on the road (Cerbera and 350i), so the mileage with this 280i was not much. But still, I am not expecting them to wear too much, as with my other cars that I have used SuperFlex bushes, the longest experience is a 400hp Cortina based Pilgrim Sumo kit car still on the same bushes fitted some 10 years ago.

See some shots of the 280i project: http://jannenr1.kuvat.fi/kuvat/Projektit/TVR+280i/

If you want a proper engineered solution than you aren't going to find it in bodged-up brackets and a 'looks about right' approach; all you're doing is reducing the compromise(s) of the original setup. So when you've quite finished with the digs, carry on bodging.
If I want a car that handles well, I'll buy something other than a TVR. If I want to go really fast, I'll buy a (faster) bike.
I'm happy to live with my compromised TVR because... well phuckit, at the end of the day, does it really matter? It is what it is and it does what it does and my penis is quite large enough, thanks.

Simple, cheap ideas generally equate to bodged-up brackets. The Tas racers tried a clamped-on extra link to stop the t/arm slewing sideways... fine on a glass-smooth racetrack but no bloody use on the road.
TVR gave it their best shot and came up with the A-frame; surely if they didn't think it was a simple fix, it won't be a simple fix. I'm sure Steve Evans accepts that and if he wasn't happy with the compromise he'd have sold up and bought something else a long time ago.