TR6 suspension upgrade

[Steves_TR6]

So the TR6 is booked into Rees Bros at the start of May for an underseal update, diff reinforcement and polybushes, and fitting of adjustable swing arm brackets and polybushes.

 

I would like to have new road springs fitted but can't decide which ones to go for.....

 

I dont want to lower the car much if at all as there are too many 'sleeping policemen' round here.

 

I do want to stiffen the suspension up but again just a little.

 

Various suppliers offer various options :

 

Moss and the TR shop seem to offer good basic springs

Revington offer more flexibility but are dearer

Racetorations, similar to revington ?

 

Recommendations please !

 

Steve

PS I assume fitting ply mounts is recommended ??

Edited April 5, 2011 by SDerbyshire

[alanwcoote]

Morning Steve

My set up is polybush all round, front on standard shocks ( new ) and slightly uprated and 1/2 inch lowered springs ( Rimmers ). Rear, polybushed and shortly to go on TRGB / CTM upgraded suspension mounts with again slightly lowered and stiffer springs with adjustable gaz shocks ( TRGB ).Works for me, but we are all different and want different things.Think about how you drive, where,standard or breathed on engine etc. Note My car is standard in every way other than above.

Patch

[Peter Cobbold]

Its not a pick and mix decision - the front and rear ratings must be in balance. If too much rear stiffness is added without adding more to the front the car will tend towards oversteer (more turning load goes into rear tyres and that will make them slide/break first), and vice versa. That said, in standard tune the set up will understeer on the limit - its supposed to be safer!- so it will take stiffer rears (or rear antiroll bar) without changing front.

You can get more roll stiffness without stiffening the springs by fitting a rear anti-roll bar, again in balance with the front.

But you need expert advise on exactly what ratings give nice neutral steer.

Peter

[Steves_TR6]

Thanks for your thoughts guys.

 

I agree that it's important to balance any spring upgrade.

 

I'm thinking I might leave the current springs in, and see how it handles with the polybushes and correctly set rear suspension, via the adjustable brackets.

 

My objective is a car that's predictable and fun on the roads in SE England, without being too harsh.

 

Perhaps a rear ARB would be a good idea, are these recommended as I've heard differing opinions.

 

Steve

Edited April 5, 2011 by SDerbyshire

[Alec Pringle]

Hi Steve,

 

it's all too easy to waste loadsamoney on unnecessary 'upgrades'- as many of us can testify from expensive experience.

 

Peter is absolutely right. There are various suppliers of uprated suspension systems, and each designs (to a greater or lesser extent) their individual offerings as a system, a potential unity. You don't know more than they do, neither do I, so don't pick'n'mix.

 

First step rebush the whole car, not just parts of it, with either Superpro or Superflex - personally I wouldn't waste my time using anything else. See what that does for you.

 

Next step - if the springs and/or shocks are past their best, replace with new standard units, The difference will be considerable. If it still doesn't suit, the OE spec items won't have come that costly, and are always resaleable for a decent price on Forum or ebay.

 

Only then move on to relatively more expensive 'upgrades' - a/r bars, shocks, springs, whatever.

 

Bear in mind also that the uprated car that feels wonderful for a Sunday afternoon blast round the lanes . . . . can come across a whole lot different if you are holidaying fully loaded and covering 500 miles a day on motorways.

 

Think through just what you're going to be using the car for in other words !

 

Final thought, all 'upgrades' impose greater loads and stresses - tyres, wheels, suspension, steering, brakes, engine. You need to know your chasssis is in a fit state to accept these additional inputs before committing yourself to further expenditure.

 

Cheers,

 

Alec

[jerrytr5]

Perhaps a rear ARB would be a good idea, are these recommended as I've heard differing opinions.

 

 

Yes - the most cost effective handling improvement you'll ever make.

[Steve Knight]

Handling should generally be controlled by springs ( and shocks, geometry, weight etc ) Some vehicle makers never use anti roll bars. But in a compromise road car, anti roll bars are very useful. It is to control ROLL without having to use springs that are too hard. So what is happening with trailing arm TR6 ? Answer: The front ROLLS more than the rear. Look at the photo above. So fit a thicker roll bar at the front ( I use two ) Keeping the four tyres attached to the tarmac at the right angle at all times makes your car handle properly. Plus a few other factors.

[Peter Cobbold]

Yes - the most cost effective handling improvement you'll ever make.

 

 

After solid rack mounts

[Peter Cobbold]

Handling should generally be controlled by springs ( and shocks, geometry, weight etc ) Some vehicle makers never use anti roll bars. But in a compromise road car, anti roll bars are very useful. It is to control ROLL without having to use springs that are too hard. So what is happening with trailing arm TR6 ? Answer: The front ROLLS more than the rear. Look at the photo above. So fit a thicker roll bar at the front ( I use two ) Keeping the four tyres attached to the tarmac at the right angle at all times makes your car handle properly. Plus a few other factors.

 

 

Steve,

Beg to differ.

Rally cars would not regard ARBs as compromise- essential more like.

 

The front cannot roll more than the rear: the chassis is stiff. Its a question of which of the two highly loaded tyres - F or R - is causing the chassis to roll. Ideally the F and R loads should be apportioned equally so that handling is neutral.

 

Look at pics of unmodified TR6s in a fast bend show the chassis tilted, the outer rear tyre well up in wheel arch, the diagonally opposite front supension drooped, the front of the chassis raised. A bit more cornering force and the rear wheel rises further, the chassis dips onto that loaded tyre more at the rear....and the front unsticks first. Understeer, caused by too little roll-stiffness at rear

Adding a FAR to that increases roll stiffness at the front, making it even more stiffer than rear!! So more cornering load goes into front tyre, which will achieve higher slip angles than rear and slide first: even more understeer.

 

The trailing arm set up is really horrible to tune: chassis roll alters toe-in and camber, so the only thing to cure that is stiffer rear end (springs and RAR) which means stiffer front springs and FAR to bring handling back to neutral. With really bone-jarringly stiff springs and ARBs the IRS TR can be made to corner 'flat', but with a standard weight road car the spring rates are so high (in 400s IIRC) that its a pain on anything other than smooth tarmac.

 

Front negative camber helps a lot in combating understeer caused by roll.

 

What I would do in Steve D's situation is drive the car on a quiet smooth 'turning circle' (roundabout) and see if it understeers.(It might have had springs changed by PO.)

But if it does, add negative camber to the front. It costs nothing and is easily reversible. That will help reduce understeer. Then back to the roundabout.

If understeer is still unacceptable remove FAR. Costs nothing but will promote less understeer... and is easily reversible. If the car now rolls too much - it will if spring are standard,belying its boulevard tourer nature - you want to refit the FAR and add a new RAR.

What rating of RAR? Goldilocks type. Not too stiff not too soft. If you get rid of too much oversteer, and are opposite lockig around that roundabout, back off the neg camber on front.

 

Fred Puhn's 'How to make your car handle'- explains it all.

[Peter Cobbold]

And a word of warning - dont get cught by this mistake, a I did.

I was not happy with the handling - the car rolled too much - so in my ignorance fitted a much thicker and stiffer front anti-roll bar. The car felt better on the road - much less roll. That was until I took the right hand bend at end of straight at Castle Combe: the back end came round without any warning, much too fast to catch on opposite lock. 360spin. Very puzzling. I then read Puhn's book. What had happened was the outer rear spring had compressed to the point where the trailing arm contacted the chassis. This makes the roll stiffness at rear infinitely high, and all the cornering loads then go though that tyre, which lets go immediately.

So spring length and rate must ensure that travel never allows chassis contact. (so no cutting the ends off springs to lower them)

I fitted a RAR.

[Steves_TR6]

 

 

What I would do in Steve D's situation is drive the car on a quiet smooth 'turning circle' (roundabout) and see if it understeers.(It might have had springs changed by PO.)

But if it does, add negative camber to the front. It costs nothing and is easily reversible. That will help reduce understeer. Then back to the roundabout.

If understeer is still unacceptable remove FAR. Costs nothing but will promote less understeer... and is easily reversible. If the car now rolls too much - it will if spring are standard,belying its boulevard tourer nature - you want to refit the FAR and add a new RAR.

What rating of RAR? Goldilocks type. Not too stiff not too soft. If you get rid of too much oversteer, and are opposite lockig around that roundabout, back off the neg camber on front.

 

Fred Puhn's 'How to make your car handle'- explains it all.

 

 

Thanks Peter, thats a plan !

 

I shall have the polybushes and diff reinforcement done as planned, but not change the current springs.

 

The car had a body off resprak 20 years ago so who knows what springs it has on.

The ride quality is pretty good but the handling a bit too loose, which i put down to the old rubber bushes.

 

When the work above is done i know just the 'smooth turning circle' to practice on !

 

:-)

 

Steve

[Athomas]

Thanks Peter, thats a plan !

 

I shall have the polybushes and diff reinforcement done as planned, but not change the current springs.

 

The car had a body off resprak 20 years ago so who knows what springs it has on.

The ride quality is pretty good but the handling a bit too loose, which i put down to the old rubber bushes.

 

When the work above is done i know just the 'smooth turning circle' to practice on !

 

:-)

 

Steve

 

 

Steve

There is good advice here already; I especially support Alec’s view, which is pretty much where my car is.

 

Up-rate the bushes to get the best out of the standard set-up before throwing loads of money at it.

I, like many others are quick to assume that Triumph knew little; far from it, based on some of the “improvements” I have tried to make.

Two other factors that I feel are worthy of mention are wheel alignment and tyres (sorry to mention the word tyres again on the forum).

With the age of our cars many repair will have been carried out, and it’s possible that all the wheels may not be pointing in the directions intended. Now days there is probably an outfit in every town with the capability to carryout 4 wheel alignment.

Secondly, the biggest change to my handing was achieved with a tyre change, there a many posts on here already about various brands and sizes. Just don’t underestimate the contribution of the rubber.

Tyre technology has made great strides in the last 40 years.

For the everyday road use my 6 gets, a sorted standard setup can still put a hell of a smile on your face !

 

Regards

Andrew

[roulli]

Hi Steve,

 

I'd like to share my experience.

 

I tend to purchase my parts in UK whenever possible. But with regard to the suspension springs, I did not find anything appropriate 2 years ago, when I restored my TR6.

 

Most non-standard springs sold in UK were too stiff. I tried TRGB, Rimmer; the Blue Moss springs is what I had on my car, when I bought it.

I asked the vendors for the geometric data (wire thickness, amount of coils, diameter, length), put these values into the formula for calculating the spring stiffness, and with the exception of the standard springs the calculated stiffness was always much higher than the specified stiffness.

 

I ended up buying the "sport" springs from Bastuck. ( I'd never buy anything else from there, but the springs are supposed to be from H&R and do come with a TUV certificate). Last but not least, I believe they're a great compromise for the (fast road) TR6.

 

http://www.bastuck.de/shop/index.php?lang=en

 

front springs VA72aTR

 

rear Springs HA15aTR

 

I do use the CTM telescopic conversion at the rear end, and spax dampers on the 4 corners plus Superflex bushes all over & Goodparts adjustable Trailing arm brackets.

 

Best,

Patrick

Edited April 6, 2011 by roulli

[Peter Cobbold]

I align the rear wheels' toe against the front. Drive car to and fro to settle tyres on road, and ensure it is level, front wheels straight. Fit (ie wedge) straight edge on centre-line of rear tyre, step back a few metres and with one eye see if straight edge is pointing at edge of front tyre's centreline. It wont be, so adjust shims on trailing arm brackets until parallel.

Cheap laser level from eg screwfix could refine the squinting bit.

 

Front geometry should be done beforehand.

[Guest ntc]

I align the rear wheels' toe against the front. Drive car to and fro to settle tyres on road, and ensure it is level, front wheels straight. Fit (ie wedge) straight edge on centre-line of rear tyre, step back a few metres and with one eye see if straight edge is pointing at edge of front tyre's centreline. It wont be, so adjust shims on trailing arm brackets until parallel.

Cheap laser level from eg screwfix could refine the squinting bit.

 

Front geometry should be done beforehand.

 

 

And how do you see the difference in the track ie 6mm?

[Peter Cobbold]

And how do you see the difference in the track ie 6mm?

 

ntc

Thanks for the reminder - many years since I had to do it (silentblocs on rear hold alignment really well).

I align the required mm in from edge of front tyre: stick tape on tyre mark with pen.

Peter

[Guest ntc]

ntc

Thanks for the reminder - many years since I had to do it (silentblocs on rear hold alignment really well).

I align the required mm in from edge of front tyre: stick tape on tyre mark with pen.

Peter

 

 

Your welcome,the front is wider than the back

[paul83]

Steve,

 

Don't use Racetorations, spend your hard earned cash elsewhere. The office know why.

 

 

 

Paul,

 

What's the problem with Racetorations?

 

Paul