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ChimpofDarkness

Original Poster:

4,789 posts

67 months

[news] 
Thursday 4th October 2012 quote quote all
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?



Edited by ChimpofDarkness on Thursday 4th October 13:12

grahamw48

9,918 posts

126 months

[news] 
Thursday 4th October 2012 quote quote all
I'm sure the Dunlop Challenge racer guys will be able to comment.

Has anyone converted to A-frames...if that's feasible ? scratchchin

SporttiJanne

104 posts

39 months

[news] 
Thursday 4th October 2012 quote quote all
I fitted these polyurethane bushes instead of the original rubbers: http://superflex.co.uk/proddetail.php?prod=SF111-1...

ChimpofDarkness

Original Poster:

4,789 posts

67 months

[news] 
Thursday 4th October 2012 quote quote all
SporttiJanne said:
I fitted these polyurethane bushes instead of the original rubbers: http://superflex.co.uk/proddetail.php?prod=SF111-1...
Interesting, as a rule I'm not a huge fan of poly bushes but I'm open to it in this case.

How are you finding them Jean?

Is the movement greatly reduced compared with the standard rubber ones?

How are they lasting?

How long/many mile have they been on?

Any excessive wear in the poly bush yet?

Sorry for all the questions, I'm just curious wink

hallsie

2,064 posts

108 months

[news] 
Thursday 4th October 2012 quote quote all
ChimpofDarkness said:
SporttiJanne said:
I fitted these polyurethane bushes instead of the original rubbers: http://superflex.co.uk/proddetail.php?prod=SF111-1...
Interesting, as a rule I'm not a huge fan of poly bushes but I'm open to it in this case.

Sorry for all the questions, I'm just Bi-curious wink
wink
How is Gavlar these days?

Stu

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ChimpofDarkness

Original Poster:

4,789 posts

67 months

[news] 
Thursday 4th October 2012 quote quote all
hallsie said:
wink
How is Gavlar these days?

Stu
He's all good Stu, apart from trying to drop his Wedge on my head.... (my fault not his) biggrin

Its the Watford beer festival in a few weeks, so we'll be having beers again very soon beer

We need to make that a no TVR day wink

SEvans

1,030 posts

155 months

[news] 
Thursday 4th October 2012 quote quote all
Not a total solution but inexpensive and does help. Cheers Steve



ChimpofDarkness

Original Poster:

4,789 posts

67 months

[news] 
Thursday 4th October 2012 quote quote all
SEvans said:
Not a total solution but inexpensive and does help. Cheers Steve


Like it, looks like an excellent cost effective mod Mr SEvans wink

Keep your solutions coming Wedgies.

I knew you boys would have a fix (or two) thumbup

adam quantrill

7,908 posts

130 months

[news] 
Thursday 4th October 2012 quote quote all
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.)

Wedg1e

25,136 posts

153 months

[news] 
Thursday 4th October 2012 quote quote all
adam quantrill said:
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.)
They're not for torque reaction (or if they are, whoever thought it up needs a slap) - Joolz Lane identified several years back that the connection point is too close to the axle centreline to have any effect. It seems more likely that it's an adaptation of the Jaguar link that creates toe-in on turn to reduce oversteer.
I guess it'd be a fairly simple mod. to weld some plates on to move the tie-rod locating point away from the axle centreline - but who knows what the effect would be until someone tries it?

Wedg1e

25,136 posts

153 months

[news] 
Thursday 4th October 2012 quote quote all
ChimpofDarkness said:
Words
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... wobble
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 smile

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.

ChimpofDarkness

Original Poster:

4,789 posts

67 months

[news] 
Friday 5th October 2012 quote quote all
Yep, get all that Ian, & I knew the history & origins already.

The important bit we shouldn't overlook within the history is both Lotus & TVR moved away from the design as quickly as they could.

This alone should tell us something, but all this was never meant to be about slagging off the Tasmin or upsetting my Wedgie mates.

I love Wedges, period.

Have a look at my intro, I was very careful to point this out right from the start, it's just all car design can be improved, lord knows I've spent nearly 4 years getting my Chimp as I want it, & it isn't over yet rolleyes

Now all that's clear lets get real.

We can pretend the Tasmin semi trailing arm set up is a good design, but the fact is from an engineering perspective it simply isn't.

We could dream up all sorts of sliding drive shaft solutions, but lets be honest they aren't really practical or cost effective.

What I was hoping for from this post was some simple ideas that offer a measurable improvement on a budget.

So thanks to Steve Evans & Jean Niemi for their real world solutions thumbup

Big up the Wedgies clap

hallsie

2,064 posts

108 months

[news] 
Friday 5th October 2012 quote quote all
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!!

wink

Stu

ChimpofDarkness

Original Poster:

4,789 posts

67 months

[news] 
Friday 5th October 2012 quote quote all
hallsie said:
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!!

wink

Stu
I'd love it, but my TVR funds are earmarked to give the Chimp a blow job..........

Did I just say that eek

I'll explain............



Aiming for 350hp (300 at the boots) on LPG.

Already have the Canems dual fuel engine management system in place.

We already have GasWedge, soon you will have GasChimp wink

One day I'll get me a Wedge biggrin

SporttiJanne

104 posts

39 months

[news] 
Friday 5th October 2012 quote quote all
ChimpofDarkness said:
Interesting, as a rule I'm not a huge fan of poly bushes but I'm open to it in this case.
How are you finding them Jean?
Is the movement greatly reduced compared with the standard rubber ones?
How are they lasting?
How long/many mile have they been on?
Any excessive wear in the poly bush yet?
Sorry for all the questions, I'm just curious wink
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/

ChimpofDarkness

Original Poster:

4,789 posts

67 months

[news] 
Friday 5th October 2012 quote quote all
SporttiJanne said:
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/
Perfect Jean, many thanks for answering all my questions.

Great photos too, I'll bookmark your link for future reference.

I also like Steve Evans's billet ally bush cage on the standard rubber bush.

Perhaps Steve's idea could be used on the SuperFlex poly bush for a completely fit & forget super well located solution?

I'm thinking a two part kit here.

Poly bush plus billet ally cage?

A complete DIY solution in one box, with no need to completely re-engineer the rear end of the car.

Edited by ChimpofDarkness on Friday 5th October 14:36

Wedg1e

25,136 posts

153 months

[news] 
Friday 5th October 2012 quote quote all
ChimpofDarkness said:
real world solutions
rolleyes

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.

ChimpofDarkness

Original Poster:

4,789 posts

67 months

[news] 
Friday 5th October 2012 quote quote all
Wedg1e said:
ChimpofDarkness said:
real world solutions
rolleyes

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.
Would we all like a proper engineered solution?

Yes.

Is that practical for the average Wedge owner that just wants to improve & enjoy his car on a realistic budget?

No.

"All you're doing is reducing the compromise(s) of the original setup"

Excellent, exactly what I was looking for thumbup

Believe it not, between the irrelevant worn out Chimp suspension point & bizarre penis reference we still ended up with some simple cheap ideas that should make an improvement on a compromised design.

I wouldn't call them "bodged-up brackets".

That would be disrespectful & rude to the nice people that were kind enough to add their constructive input.

byebye

Wedg1e

25,136 posts

153 months

[news] 
Friday 5th October 2012 quote quote all
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.

Rockettvr

888 posts

31 months

[news] 
Sunday 21st April 2013 quote quote all
SEvans said:
Not a total solution but inexpensive and does help. Cheers Steve


Hi all
I'm going to replace my bushes and pins soon and would like to add the "cages" as in the pic above.Can anyone tell me where i can get said cages. I'm certain that they're not available off the shelf but made. Where can i get some made or can someone on here obtain or make some for me? - (beer tokens await) I would PM SEvans but cant remember how! (totally computer illiterate)confused
Thanks in advance Ron smile
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