Jump to content

Rear Leaf Spring Elimination Kit


Recommended Posts

  • Replies 112
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

The hic was, I hadn't realised at the time, there was a reason Triumph put rubber bushes in the radius arms....it was to cope with the stupid toe in/toe out variations and the messy geometry.

The moment you anchored it solid it would try to tear itself apart.

 

Gosh, thanks, GT!

The Sb version was, as I said, merely a doubled radius arm, with rubber bushes.

On SofS, with a spherical jointed wishbone and the OE transverse spring, I used a solid radius arm with a spherical on the wishbone for toe adjustment.

I didn't bother to make the inner end of a radius a spherical too; really laziness not design!

And now you say, I was right not to do so!

Thanks!

 

John

Link to comment
Share on other sites

.....rod ended radius rods ripping mounts apart. All this is greatly exacerbated by running on wide racing slicks...

 

Actually beg to differ on the slicks aspect.

I don't know if I am the only person ever to have used them on one of these Triumphs, but I used Michelin SB49 on the front and SB20 on the back (typical hillclimb stuff), and they were literally AWESOME.

The front had 7" rims and the rear 8".

This seemed to suit the car very well.

 

Most of the strange behaviour instantly vanished and the level of adhesion was well.... a bit like driving a good well sorted Lotus 7, except without the immediacy of reaction or the chronic understeer you get on one of those, and about TWICE the level of grip.

 

I would do things very differently today, (certainly an 8" front rim and a 9-10" rear) but...........

I DID put proper bearings in the lower out trunnion instead of nasty sticky bushes, and I left TWO very important places to pick up the slack.

ONE was the inboard bush of the lower wishbone, which I left in rubber (it could do with a rose joint there), and the other of course was the diff rear housing (would REALLY make them solid today), and of course the spring eye, which seemed to joggle fore and aft to cope with the stupid false arc of the radius arm.

 

I suppose you COULD put a rose joint in the eye of the transverse spring but it would need to be one which wasn't fixed..ideally would have to slide fore and aft in some sort of a collar......

 

If you bear in mind you cannot run an 8" rim with a slick on and get really good grip unless the rear geometry is correct, then I have to assume it was, because the tyre wear pattern was excellent too.

 

If I remember right it HAD to run at least 1 degree negative camber and some toe in.

(but of course you measure it from the back so it's TOE OUT right?)

 

I didn't have to use excessive front negative camber, because I suspect the chassis was much more rigid than normal, and didn't stack up a whole heap of extra flex to throw a wobbly into what we dialed in....

 

(it was the only Herald type chassis I ever saw where you could jack up the chassis wherever you wanted (including the side riggers) and it made no difference whatosever to the doors opening or shutting properly.

 

I wouldn't knock the Mk2 suspension PER SE.

Have you ever tried the trailing arm system on a Sierra?

 

The Triumph is in a different league from that and on the limit it DOESN'T swap ends suddenly,- it's fully opposite lockable even when you've TOTALLY overcooked it!

Link to comment
Share on other sites

You can stop acting as if you invented the damned sport!

 

Big deal, but back in 1983, you seem pretty interested in what we were doing then.

I met P Lucas actually when I was just leaving school......so what?

I reckon you were still going around in short trousers. :yes:

 

I have LONG militated for the more widespread use of Slicks in UK motorsport (in which you have played no part whatsoever), because I consider them MUCH SAFER, and ultimately cheaper to use.

I still consider it DANGEROUS for people like JEC to be advocating a control tyre, as it's lethal in the wet.

 

Years ago slicks were slicks, and road tyres what you drove to work in.

 

Today many performance road tyres outperform yesterday's slicks, and most of the drivers you are talking about are stuck in a poor man's motor sport in the states, with stupid outdated rules and american horsepower.

 

Don't talk to me about motor sport, the UK is still one of the most interesting, most advantageous countries in the world, and the outstanding names of Lola, Lotus, Pilbeam, Reynard, and many others just serve to underline it.

 

When did any of you in the states start tuning Minis, Jaguars, Rovers, or start something called Group A or Group B, never mind the Cosworth engines from the tiny little MAE to the all conquering DFV?

 

huh!

I am talking about the UK here, nothing to do with what you yanks are doing and still struggling to get 100bhp/L from a race engine despite all the talk!

Link to comment
Share on other sites

I'm still damned interested in what you all are doing. Cuz we're advancing the sport. But there's more doing it than the immortal Exile. There's thirty times as many Spitfire racers in the USA than you've ever met Gareth. And maybe one of them might've accidently learnt something about these cars without your magnificence. Jeez Man, get over yourself!

 

And we've got tuba players here as well!

Link to comment
Share on other sites

There's thirty times as many Spitfire racers in the USA than you've ever met Gareth.

 

If only you could get used to the fact, I'm not in the slightest interested in meeting a single one of them.

Don't want any to contact me. Not interested in the USA.

 

I think you must realise by now why.

Link to comment
Share on other sites

Topic as seen from a lesser qualified members eyes ,

The commonly questioned rear end issues ,

Without getting TOO tecy ,

Weak diff ,

Weak Rotoflex design/supply ,

Weak VL/bearing ,

Drums potential regards overheating/fading .

Instability of VL due to suspensions geometry fluctuations ,

Unwanted changes in camber induced by badly matched wishbone/spring lengths ,

 

Simple solutions ,

Change diff ,

CV conversion ,

Fit alt' VLs , bearings etc , MGF/MG/ Saxo or whatever ,

Also discs/ callipers ,

Stabilise VL with a wide solid twin mounting point wishbone , or additional radius arms .

Ditch the rear spring for a more balanced upper/lower wishbone set up .

 

I have not seen KDs latest version , but he said it has been redesigned with triangulated inboard half arms prior to the threaded adjustable joints which must remove the correctly suggested flexing of the inner mounts and if the VL is now totally stable due to the now substantial lower wishbone and if the upper wishbone diff mount plate is wide enough to shorten the upper arms reducing the camber variations .

If all these steps are taken surely this has to be a substantial step in the right direction .

 

But do feel free to criticise , it's where I learn from .

 

Probably simpler still to give Jango a call although come to think of it I do not recall seeing any recent updates on this system , any info/links anyone ?

 

Or just buy a Superlight R500 .

 

Link to comment
Share on other sites

I have not seen KDs latest version , but he said it has been redesigned with triangulated inboard half arms prior to the threaded adjustable joints ......

If you trust KD or anyone from Coventry for that matter to have anything to do with so called "designing" or "modifying" anything, they have men in white coats looking for people exactly like you.

Edited by GT6MK3
Initialise KD so google doesn't send all his traffic here..
Link to comment
Share on other sites

Seriously.

NPCs from Vegas should steer clear of the Lager on saturday nights!

 

Actually I don't agree with any of this:-

 

Weak diff,

not 100% agreed, usually they smash because badly set up or 35 years old

 

Weak Rotoflex design/supply ,

Problem is PRICE as they are made no longer by DUNLOP but Trelleborg who aren't the world's easiest co to deal with.

 

Weak VL/bearing.

Absolutely untrue, the Timken bearings used are even bigger than on my Jag front wheel bearings 2x the weight, the VL is MASSIVELY over engineered, which is good.

Just compare it with that heap of rubbish from the Herald!

 

Drums potential regards overheating/fading .

NEVER EVER HAD, in fact I had to upgrade the rear cylinders to Marina ones to get it to make more braking force.

If you have a LSD you will never max out the rear brakes.

 

Instability of VL due to suspensions geometry fluctuations ,

NEVER SEEN, you just need to control it properly

 

Unwanted changes in camber induced by badly matched wishbone/spring lengths.

 

PARTIALLY true, but usually caused by TOO SOFT a rear spring rate.

The rear spring rate although being variable I suspect rates between 200-300lbs on STD GT6 cars.

I suspect the Vitesse rear spring rate is around 250-420lbs judging by how much it sank when overloaded or with 4 persons in.

(The big red book never gives a pound rating figure and it's not easy to measure).

 

The geometric settings would have been heavily modifed by the fact I added a purpose made slotted spacer about 1" thick between the diff top housing and the bottom of the leaf spring.

 

As you can see, this large difference in "top wishbone" pickup point would make the entire suspension operate in a different datum area, where the suspension travel would tend to make the rear camber go strongly negative, consistent with roll angle.

 

I strongly suspect the race rear spring I used was in the 400-700lb rating area, as the front springs I used at the time were MGB (linear) race ones of about 570lb rating, and the thin STD original front roll bar with solid mountings.

 

Any attempt to increase the front roll bar rate was met by stronger and stronger understeer.

Any addition of a rear roll bar, just made the car oversteer completely uncontrollably on the limit.

I have only ever made TWO new front roll bars for these cars, and they were specially made last year.

 

Today I would do things very differently.

A set of (my) springs recently fitted to a customer's TR6 in Germany also resulted in having to throw away the rear (Basteln) roll bar, and were a zillion times more progressive and comfortable, with excellent grip in all conditions.

You are welcome to contact him to find out, what he thinks.

 

If you insist in using road rated springs in a race application, then of course the geometry is NEVER going to be right.

More cornering force=more suspension travel=badly set up suspension for this app.

Link to comment
Share on other sites

:huh: NPC comment is laughable...... Steve has being doing as much as just about anyone alive with development and racing of GT6s.... with some notable successes too.

 

Would also like to point out that there is WORLD of difference between road going and circuit racers (with or without slicks, but slicks up the level again). For road use, even spirited road use the roto set-up is not that bad. I like the way my Vitesse handles - main limitation there (and it's a biggy) is the wibbly wobbly chassis.

 

As for roto wheel bearings - the bearings themselves may be decent BUT: In these days far removed from when the cars were built:

Problem no. 1 is than many bearings sold for the job are not Timken (or even Timken made "elsewhere") which are rather less robust.

Problem no. 2 is that the hubs themselves fail - usually at the thin part where the inner bearing sits. This could easily (and quite probably correctly) be blamed on incorrect set-up, crappy bearings or just plain old wear and metal fatigue, but it is still a fact of life these days - and not just on racers.

 

Nick

Link to comment
Share on other sites

I guess you know what a NPC is cos you are not one of them. :sick:

 

As for the rest:-

 

The bearings themselves may be decent BUT: In these days far removed from when the cars were built:-

 

ERR, you just go and BUY them from a Timken dealer.

The inner one is in fact EXACTLY the same bearing as fitted to the front wheel of my Jag....current mileage 155 000.

If you don't like to buy from a dealer, buy it from Jaguar.

 

Problem no. 1 is than many bearings sold for the job are not Timken (or even Timken made "elsewhere") which are rather less robust.

NEVER SEEN THAT, never fitted anything other than Timken. Why bother for the sake of a fiver?

i can get them off the shelf whenever I want just like the genuine rear bearings from RHP for the Spitfire.

 

Problem no. 2 is that the hubs themselves fail - usually at the thin part where the inner bearing sits.

NO THEY DON'T if you make sure it's all fitted up properly with the right preload.

Why should they fail?

 

The inner wheel bearing is extremely lightly loaded for its size.

The outer wheel bearing is highly over engineered for what it has to do.

It's got to rate as the largest wheel bearing I have ever seen for a car of its size.

 

I would say the vast majority of failures are the result of the ingress of water through the leather seals through sitting for years in conditions conducive to formation of condensation (n'est pas?)

 

This could easily (and quite probably correctly) be blamed on incorrect set-up, crappy bearings or just plain old wear and metal fatigue, but it is still a fact of life these days - and not just on racers.

 

The ONLY weakness in this system is if the inner wheel bearing spins on the hub.

This is even worse on the TR6 which has tiny bearings in comparison, and the TR6 diff carrier.

I don't hear anybody criticising those cars, despite the fact the consequences usually result in catastrophic failure.

 

Just because people are incapable of rebuilding or setting stuff up properly doesn't mean it's a bad design.

 

As far as I am aware the Mk2 Vitesse rear wheel hub has been remanufactured 149051 costs - £114.

It's an EN24 forging originally, but it may very well be it's now made from solid.

If you compare it with a similar part for a Jaguar, it's not excessively expensive as they are £191 for the same sort of part.

 

As for genuine rotoflexes they are £186 ea, which would mean rebuilding the entire rear suspension with new bits is going to cost somewhere around £1000.

Again not excessive, when you consider the cost of doing just the gearbox, engine & axle, and it may have already lasted 30 years.

 

149051.jpg

 

GCD301.jpg

Link to comment
Share on other sites

I completely overlooked this fact.

The Vitesse Mk2 and GT6 Mk2 outer rear wheel bearing is identical to the TR6/Saloon/Stag outer wheel bearing.

(GHB265) & is the same as GHB112.

Mr Dolphin stocks these for all of 9.50 Quid.

 

This is not a difficult bearing to get and is very sturdy.

Timken part number is LM 29749 (cone) LM 29710 (cup)

 

On the TR6 etc the inner bearing is by comparison a stupid weeny little thing L 44649 (cone) L 44610 (cup), and it makes the drive shaft too small to carry the loads as a result.

 

On the GT6 this is a whopping great UKC 169

(which I know much better as a Differential carrier bearing under the Timken number 67048/67010, so common as muck!)

 

Now my mistake, this bearing is NOT used in the Jaguar, instead they use the later even bigger (metric convertor) outer carrier bearing from the later 1500 diff, 68149, but with the 68111 rather than the 68110.

 

The effect is pretty much the same.

Your Mk2 rear INNER bearing is designed to be able to carry a 1.8T car on ONE WHEEL as the outer race has the same OD exactly as the Spitfire diff carrier bearing.

The Jaguar front outer bearing is 45449/45410, which is quite similar in size to the TR6 rear inner wheel bearing, but a bit bigger.

 

Jaguar charge £18.85 for 68149 / 68111 in OEM.

Rimmer charge £14.00 for the UKC4805 (68149/68110) in who knows what?

 

I've said this before but the GT6 has got really nicely over-engineered stuff in a lot of places (apart from the gearbox and axle).

The front wheel bearings and stub axle are nice big things on the GT6 & never wear out, (GHB101/102) 44649/44610 which as you can see is the same bearing as used on the TR6/saloon rear, but without a nasty key way to weaken the shaft.

 

......unlike the TR6 which has nasty yuck bearings from a HERALD/Spitfire! (GHB110/111) 07100....

 

One of the worst bodge ups I have ever seen this summer, was where Revington in an effort to "UPRATE" the thing rather than fit a proper larger stub axle, fit a shimmed distance piece and collar to so called "stiffen" this stupidly weak stub axle.

 

The GT6 has an undertuned engine which can get a 50% increase in power doing nothing whatsoever to it apart from flowing the head (98>148bhp).

It also is safe to 7000rpm in standard form.

 

Lots of that stuff on the GT6 was good quality, and cost too much to make.

 

Remember that.

Link to comment
Share on other sites

A few points from various posts:

 

Steve

Yeah is lamentable that the US has the greater amount of Spit racers. The big TRs are still popular, but the small chassis cars are in serious decline with probably only around 10 still racing, probably less, certainly not much more. Plus I think I’m going to drop out the ranks for a year in 2013 too as am finding it difficult to both race and maintain the Spit to the level needed so am having a fixing year.

To be honest I’ve no interest in advancing the sport I just want fun weekends and to beat that pesky Frogeye that is just pipping me at the moment. Which I can do once I get up to the level of detail preparation he does, rather than just dragging my car out of the dusty barn a day before I run it!

 

GT

Slicks are not ‘safer’, as are control tyres not ‘safer’ either. A tyre is a tyre, and the grip it gives you is a factor of that tyre. Control tyres are an excellent leveller for a championship and those who complain about them are those who are unable to set up their car or develop their driving skill to suit them. It’s not the tyre that loses grip, it’s the person controlling the steering, accelerator and brakes.

 

Spit131

Diffs. I think they’re fine for a nice light spit and have never had any problems with both my standard open diff and Quaife tbd. Though have seen my big power 6 clylinder GT6 counterparts changing diffs pretty often. They seem to think that having specific cooling arrangements and regular oil changing helps in their longevity though (but still have problems).

 

CV conversion is ace and anybody who wants to take their small chassis Triumph on the track should do this (Nick and Josh should get a medal for the work they did here). It is about 20KG heavier than a swing spring but your back wheels will stay attached! I think using a Rover/MGF vertical ink is a good way to make this work as the bearings fit straight away and the rotoflex VLs are too tall for a low riding back end. I’ve not tried rear discs yet but perhaps my 2013 rebuild will do this.

 

I am entirely unconvinced with any of the coil spring conversions being muted because with the coil spring off-centre to the rear of the VL it will inevitably twist the VL with every suspension movement. Jango’s is the exception here with the wide upper and lower wishbones constraining the twist. A single link upper will just not do the job.

 

My spitfire drums used to overheat, the boiling fluid symptom I chased for a year at the front end with ducting/vented discs/twin pot calipers turned out to be the rear cast drums happily collecting heat. A pair of alloy finned drums fixed this.

 

Cheers

Andy

Link to comment
Share on other sites

OK, the bickering aside, here is my latest thoughts on what to do (to replace the spring and have a proper IRS rear suspension within the SCCA rules (I hope).

1- a box section tube bolted to the top of the diff at the proper height and attached outboard as far as possible to the frame.

2- an upper control arm of large dia tube with Delrin(sp?) bushed tubes at each end to resist as much twisting as possible, located at the outer ends of the beam to give proper camber gain geometry.

3-lower A arm consisting of a tubular "wishbone" replacement with rod ends for adjustment and stability. A radius rod attached to it and the frame with rod ends for adjusting toe and controlling fore/aft movement (and twist?)of the upright.

4- and of course an appropriate coil over unit.

 

So tear into this one please.

post-1494-0-23878600-1351551382_thumb.jpg

Link to comment
Share on other sites

GT

Slicks are not ‘safer’, as are control tyres not ‘safer’ either. A tyre is a tyre, and the grip it gives you is a factor of that tyre.

 

Control tyres are an excellent leveller for a championship and those who complain about them are those who are unable to set up their car or develop their driving skill to suit them.

 

It’s not the tyre that loses grip, it’s the person controlling the steering, accelerator and brakes.

 

Totally and utterly disagree with the above.

Any professional racing outfit will say the same.

 

The difference between professional and cheap club level motor sport is exactly that.

Are you somehow saying that professionals don't know what they're doing?

 

The fact is,- control tyres are both dangerous and disappointing because they introduce a nasty road tyre environment into an area which it is completely unsuitable....excessive temperatures, unstable grip, out of design limit loads & tyre pressures all over the place.

 

They are disappointing because they lead to 3 lap races from 15.

 

The first lap and a half warms them up, the laps 2-4 and a bit are the fastest, then by the 5th the tyres are already gone off, and the rest of the 'orrible race experience is concerned with getting a nasty piece of crap around and off the circuit in one piece without crashing into someone else, who also has very little control.

 

We all know what overheated tyres do under braking don't we, then what happens when they hit a patch of damp.

Most of those races end up with 15 cars in the gravel traps and 10 finishers looking more like banger racing than motorsport.

 

In the Triumph races it was pretty much the same, except most of the DNFs were wheels falling off with stupid things like broken half shafts, & engine blow ups. LOL

 

And you are honestly trying to tell me this horrible second rate experience is the way to make for a satisfying race to the flag?

 

I must add, control tyres are often used in championships where not all cars are the same weight, so it massively penalises the heavier cars. (The Jaguar series has been a perfect example of this, where some have V12 and others have straight 6).

You try controlling a 1.6 tonne 250-320bhp car, & drag it down from 120mph>80 every single lap.

It's exhausting apart from anything else, quite apart from the cockpit temperatures in summer.

 

Then, you try sticking twice the power (500+bhp) in the same car with colossal torque & the massive 4500rpm power band you get from a large 6 cylinder 24v race engine.

 

The steering & the driver is doing what it can, the car's constantly fighting off wheelspin, and the brakes are struggling to keep even close to cool, + it's all got to be in working temperature and stay there within 200yds.

Most of the time you're going sideways, and on a continental hillclimb, you have steel guard rail, a few trees, one or 2 tyres and the rest is just rock face, with a few misplaced marshalls and spectators for good measure.

 

It's FAR more demanding than driving a Spitfire will ever be, and the lap times/chrono aren't even comparable on a lot of fast circuits.

I've driven both, and nothing in the world would ever entice me back into driving on NON RACING tyres....

 

Do you realise the average single seater F2/F3000 on a french hillclimb is AVERAGING 130mph, not 65-80mph like in the UK?

 

but maybe like you say, my driving's no good, or I'm just getting slower on 4 wheels......

Link to comment
Share on other sites

What you are basically introducing in there is linear rate springing + damping & long travel suspension in the rear.

It didn't have that before, and was the main criticism of the Caterham when they moved from a live rear axle to De-dion.

In a Caterham they were counting on people being so blown away by the power/weight ratio they could no longer tell whether the car was understeering or plain evil handling on the limit.

(You only had to look at the uneven tyre wear to know what it really was).

 

The top rear link MUST be a wishbone with a top ball joint system and a different drop angle, to give positive fore/aft location.

You also will need to introduce anti dive.

 

As it stand there, the car will stand on it's nose in the corners under braking then yaw strongly across the diagonals, because the weight transfer characteristic and corner weights will vary drastically, & the car will want to hop from one extreme to the other.

 

On top of that, your coil springs incorporate practically no roll resistance, which wasn't the case with a cart spring.

Link to comment
Share on other sites

Essintially what I've tried to do was take the "slop" out of the original design leaf spring set up. Controlling the top of the upright has got to be better with this type of attachment than with the spring waggling around from the diff, and the outer end sitting in soft bushings. And moving the effective frame pivot outboard has got to improve the camber change. I certainly would like to add an upper trailing arm, but can't due to the rules. And I would use hard enough springs to minimize overall travel.

 

I admit I had not considered the anti sway effect of the leaf spring, so maybe an ARB would be needed.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share


×
×
  • Create New...