IRS Rear spring length and ride height

[Z320]

37 cm here on the rear

with standard springs, the lowest front insulators from the front I was able to find

and the spare wheel well full with spare parts and tools 

[Malbaby]

13 hours ago, qkingston said:

Having driven the car for 700 miles now, the ride height at the rear still seems rather high. I have TT4006 springs at the front and TT4211 at the rear, tyres are 195/65/15. I believe the springs are matched at 390lb and seemed to be recommended as a combination; however the measurements are 38cm front,42cm rear (wheel centre to lower lip of wheelarch), so the rear gap looks high, and there is a nose down angle rather than the other way round. I fitted poly spring insulators (but I didn't record what thickness). Should I change the rear springs for std height, I understand the 4211s are slightly lengthened?

Many thanks

David

David.....Wondering why you used the high rating 390 springs front and rear....Do you also have spacers fitted?

 

[Malbaby]

13 hours ago, qkingston said:

Having driven the car for 700 miles now, the ride height at the rear still seems rather high. I have TT4006 springs at the front and TT4211 at the rear, tyres are 195/65/15. I believe the springs are matched at 390lb and seemed to be recommended as a combination; however the measurements are 38cm front,42cm rear (wheel centre to lower lip of wheelarch), so the rear gap looks high, and there is a nose down angle rather than the other way round. I fitted poly spring insulators (but I didn't record what thickness). Should I change the rear springs for std height, I understand the 4211s are slightly lengthened?

Many thanks

David

David.....Wondering why you used the high rating 390 springs front and rear....Do you also have spacers fitted?

 

[qkingston]

Early on in the rebuild I bought a number of parts from Craig at TRBitz, those are what he recommended... I didn't know any different:) 

[Malbaby]

14 hours ago, qkingston said:

Early on in the rebuild I bought a number of parts from Craig at TRBitz, those are what he recommended... I didn't know any different:) 

IMHO...390's are way over the top.....I am surprised that you can tolerate the harsh ride.

[qkingston]

Not harsh at all

[qkingston]

So I have continued to try and find a solution to this issue and contacted Craig @ TRBitz where I purchased the springs: this was the conversation,

Hi Craig,

                You may recall that at the beginning of my 4a IRS rebuild (2018) I bought a number of parts from you including the front & rear road springs; you recommended the TT4006 (front) and TT4211 (rear). The fronts sits fine on the 15” wheels with 195/65/15 tyres, but the rear ride height is rather high . I believe that the TT4211 spring is the same rate as the 4006, but is also slightly longer than stock, is that correct? If so what would my best option be to lower the rear height by about 1.5” and match the tyre to wheel arch gap – current front = 2”, rear = 3.75” whilst not introducing any other mismatch. ( I also understand the car should have a slight ‘nose up’ attitude?)

Hello David,

There is an issue with any springs that are bought today, they are all much much too high and are too tightly wound with heavier duty coils. We have to cut every spring down that we fit. In 2018 the springs were of a different manufacture but they are no longer in business. If it were my car I would remove the springs and cut a quarter of a coil off them and re-fit. That should give you what you are looking for.

Any thoughts on this, I've not heard of cutting down springs before

Many thanks

David

[Z320]

Hi David,

I would send him the springs and demand my money back.

And I recommend you to fit the old ones, they do a love job on my TR4A since 1967.

Ciao, Marco 

[stuart]

Not a recommended way to go but back in seventies to lower a spring it was out with the oxy torch and warm up the spring until the car settled enough!

Stuart.

[Malbaby]

On 10/14/2022 at 3:39 AM, qkingston said:

So I have continued to try and find a solution to this issue and contacted Craig @ TRBitz where I purchased the springs: this was the conversation,

Hi Craig,

                You may recall that at the beginning of my 4a IRS rebuild (2018) I bought a number of parts from you including the front & rear road springs; you recommended the TT4006 (front) and TT4211 (rear). The fronts sits fine on the 15” wheels with 195/65/15 tyres, but the rear ride height is rather high . I believe that the TT4211 spring is the same rate as the 4006, but is also slightly longer than stock, is that correct? If so what would my best option be to lower the rear height by about 1.5” and match the tyre to wheel arch gap – current front = 2”, rear = 3.75” whilst not introducing any other mismatch. ( I also understand the car should have a slight ‘nose up’ attitude?)

Hello David,

There is an issue with any springs that are bought today, they are all much much too high and are too tightly wound with heavier duty coils. We have to cut every spring down that we fit. In 2018 the springs were of a different manufacture but they are no longer in business. If it were my car I would remove the springs and cut a quarter of a coil off them and re-fit. That should give you what you are looking for.

Any thoughts on this, I've not heard of cutting down springs before

Many thanks

David

As Marco suggested, send the springs back for a refund. TRBitz are talking rubbish about springs.

Go back to the original spec.

Edited October 15, 2022 by Malbaby

[Z320]

The construction of the springs on both ends is „layed on and grinded“, they can stand by themself.

This is needed, according to the area where they are based on the car.

Ask yourself what happens when you follow  Craig‘s advice.

More I don’t want to say, saying honest words some guys blame me being impolite.

Ciao, Marco 

[qkingston]

Many thanks for the helpful replies, I agree ref the TR Bitz advice. If I changed the rear springs to the TT4212, would I need to change the fronts as well to match the spring rates?

Many thanks 

David

[Drewmotty]

Springs always need to be matched front to rear for ride height and rate. Go to a technically biased supplier (I recommend Revington TR) and change the lot. It’s likely that you will be surprised at the improvement. 

[BlueTR3A-5EKT]

Triumph changed the trailing arm mounting brackets when the longer rear spring was introduced (216275)    Could your problem be solved by that?

We used to sell (1980’s) the unique TR6 trailing arm mounting brackets to professional/specialist TR repairers and restorers when also supplying the the  216275 rear springs for all IRS TR models that were not TR6.   I guess they solved the high back end problem with these brackets.   Those with more hands on cars knowledge can advise further.

 a set of standard coil springs for sale on here.   By. Part no they are standard TR6

216275 are rears.  213165 are fronts 

 

Edited October 17, 2022 by BlueTR3A-5EKT

[Z320]

I’m out

Edited October 17, 2022 by Z320

[Bfg]

David, cutting down coil springs was not unusual back-in-the-day and was done by cutting the spring, and then use an oxy-acetylene torch to bend the cut end of the wire down, after which the hard edge of the wire would be ground down to be flat.  This is as Marco describes.   It is something some old school garage and race mechanics learnt to do well, but equally something which many boy-racers tried at home and fouled up.  Not for the novice to try, not least for the upset to the car's handling if you get it wrong ..and then subsequently have to try to explain to an insurance underwriter. 

I concur - send them back for a refund. 

However.... When I examined mine, fitted by M&T during Katie's  chassis change (and the car was then sitting far too high).. I found no discernible difference in the springs fitted.. to those that were on the car beforehand.  Side-by-side comparison revealed the number of coils, the wire's diameter, the un-sprung length, and even the compression under part load - all measured the same.  What had changed though were the rubber vibration-isolation collars ..between the coil & the chassis and again between the coil & the arm.  The new rubbers were much thicker than the old (pre-compressed) ones.  I changed these (top and bottom) and lowered the rear-suspension's ride height - by a similar amount to what you would like.

Regarding, matched springs front and rear..  The motor manufacturer determines first by calculation, but then tuned by repeated road testing trial and error which are the most favoured spring rates, front and rear, for any particular model of car and tyre.  Very likely, the issue we now have is that aftermarket TR6 springs are commonly being supplied for the TR4A.  The springs supplied may be from another make of car altogether, rather than specifically made for the TR.  But even if they were made for the TR5 or 6 - those cars not only have a different weight, but also a different front to rear weight distribution for any given load condition.  And the rear suspension squat experienced with 150 bhp or more TR5 or 6  is going to be very different to that to a TR4A modestly tuned road car.  For my own TR4A, which is enjoyed for trundling around the countryside back lanes - the springs do not want to be too stiff, otherwise the car rides as if on a pogo-stick (..and yes this car's dampers do work fine).

In my opinion ; if you're happy with the front spring rates and their ride height, then it's perfectly sensible to keep them while you change the rears (&/or their rubber vibration collars).  And only once everything is sitting about right, and the toe-in and camber angles are within spec, and the dampers are all good - can you sensibly assess whether the front or rear spring rate is good for your own particular driving style, the roads you typically drive, and the load conditions you most frequently have (passenger, luggage, spares, fuel levels, etc). 

Hope that helps,

Pete

 

 

Edited October 17, 2022 by Bfg

[qkingston]

Pete, that's really useful thank you. The new(ish) springs were supplied with a TT prefix which I presume stood for Triumphtune (they still exist at Companies House), so I would like to think they were made for the TRs, but as you say they may well be optimised for the more numerous 6. I'll have a look at the spacers/collars to see what I have and decide then

Regards

David

[qkingston]

I've done some further research by speaking to most of the main parts' suppliers and got no straight answer tbh (not helped by the different part numbers used), however it would appear as Pete says, that TR6 rear springs (420lb) are regularly recommended and sold to 4a owners. One of the bits of advice I got was that TT4216 springs were the optimum, however they hadn't seen them for years....So I was rather surprised to see Abingdon MG (David Manners Group) advertising TT4216s for the TR4a/5/6 for £26.34 inc VAT!! Confusing. Incidentally Revingtons fit 400lb springs at the front of a 4a IRS and 450lb springs at the rear

Regards

David

[Malbaby]

On 11/3/2022 at 6:17 AM, qkingston said:

I've done some further research by speaking to most of the main parts' suppliers and got no straight answer tbh (not helped by the different part numbers used), however it would appear as Pete says, that TR6 rear springs (420lb) are regularly recommended and sold to 4a owners. One of the bits of advice I got was that TT4216 springs were the optimum, however they hadn't seen them for years....So I was rather surprised to see Abingdon MG (David Manners Group) advertising TT4216s for the TR4a/5/6 for £26.34 inc VAT!! Confusing. Incidentally Revingtons fit 400lb springs at the front of a 4a IRS and 450lb springs at the rear

Regards

David

IMHO...400 plus lb springs are ridiculous.

[Rob Salisbury]

I seem to remember Colin Chapman of Lotus fame saying you need Soft springs and Hard dampers for good road holding, then again I'm sure the roads were much smoother back in the 60's!!

Cheers Rob

[rvwp]

Hi Guys

On the question of rear camber adjustment, and the use of various combinations of U brackets, is there an alternative method of changing the brackets without removing the Drive shaft and spring to lower the Trailing Arm and unbolt the brackets.

Currently, I need to adjust my rear camber after fitting new 350 lb springs, it's such a chore to keep having to remove drive shaft/spring etc, ( 350lb spring need to be removed with a spring compressor as car lifts with a jack) guess the bracket combination, rebuild and lower the car, then have to do it all again if not correct! 

Thanks Rich

[BlueTR3A-5EKT]

On 11/3/2022 at 9:21 PM, Rob Salisbury said:

I seem to remember Colin Chapman of Lotus fame saying you need Soft springs and Hard dampers for good road holding, then again I'm sure the roads were much smoother back in the 60's!!

Cheers Rob

Chapman was correct.   Lots of well damped movement is very helpful.

Beware of this as a sweeping change though.  
 

 There is a phenomenon know as ‘jack down’.  This happens when you corner hard with soft springs and very hard dampers.   The spring remains compressed after cornering as it is not strong enough to quickly overcome the resistance of the damper.

 

[Rockie51]

On 11/13/2022 at 11:44 PM, rvwp said:

Hi Guys

On the question of rear camber adjustment, and the use of various combinations of U brackets, is there an alternative method of changing the brackets without removing the Drive shaft and spring to lower the Trailing Arm and unbolt the brackets.

Currently, I need to adjust my rear camber after fitting new 350 lb springs, it's such a chore to keep having to remove drive shaft/spring etc, ( 350lb spring need to be removed with a spring compressor as car lifts with a jack) guess the bracket combination, rebuild and lower the car, then have to do it all again if not correct! 

Thanks Rich

Rich, I would strongly recommend going to the fully adjustable brackets as sold by Richard Good at Goodparts. They make it far easier to get the correct adjustment without having to disassemble the rear of the car several times and you can get the same camber on both sides even if the chassis is not quite the same. I think that some of the other Triumph suppliers sell similar brackets. I now have .5 degrees of negative camber on both sides. I know that there are lists on the internet showing which combinations of brackets give certain levels of camber, but they depend on a now fairly ancient chassis being perfect. I suspect most aren’t. 
 

Rockie

[Britlad42]

I have just bought a 67 TR4A and round the Kent lanes find that the rear is too soft. I did a rough measurement with me sitting on the rear wing and got 3cm drop from 67.5 to 64.5cms.This looks a bit like 200lbs/inch in old numbers the front is very stiff but feels OK driving. Thinking I should be looking at 310 - 350 lbs/inch springs to avoid suspension bottoming.

Michael

[qkingston]

On 11/2/2022 at 7:17 PM, qkingston said:

I've done some further research by speaking to most of the main parts' suppliers and got no straight answer tbh (not helped by the different part numbers used), however it would appear as Pete says, that TR6 rear springs (420lb) are regularly recommended and sold to 4a owners. One of the bits of advice I got was that TT4216 springs were the optimum, however they hadn't seen them for years....So I was rather surprised to see Abingdon MG (David Manners Group) advertising TT4216s for the TR4a/5/6 for £26.34 inc VAT!! Confusing. Incidentally Revingtons fit 400lb springs at the front of a 4a IRS and 450lb springs at the rear

Regards

David

So new springs fitted with 8mm poly spring insulators as above, I'm happier with the ride height and posture, initial drive round the block shows no obvious issues. Incidentally I've seen comments from some of our suppliers re the use of springs spacers; are they commonly used or only when necessary?

Rgds

David