Front suspension height

[AJAS]

Just back from the classic car and restoration show. Had a good chat with the very helpful owner of the original spec red 6 and another chappie who appears to have the same problem as me....

I've replaced all the bushes / trunnions / track rod ends with standard items. I now have fitted a second set of shocks (Gaz adjustables) after I returned the first set for being over 30mm longer than standard! I also replaced the springs for standard items. Despite not fully tightening the bolts up, the car sits as if it's ready for takeoff! Despite vigorous bouncing of the front, the height from floor to the arch is 28 and 1/4”, allowing my full hand width between the top of the tyre and the arch. I believe it should be under 27? Comparing the red one on the stand with mine is like chalk and cheese!

I haven't driven it yet as I am about to do the rear suspension, but I'm reluctant to buy replacement springs in case I end up with it looking like a jacked up 4 x 4!

Anything that I should be checking that I may have overlooked?

Thanks 

Tony 

[saffrontr]

Tony,

You are correct with the circa 27". When new the TR6 Homologation papers gave 26.75" at the front and 27" at the rear as the distance from ground to the arch so that's what you should be aiming for. Not sure why yours is so high but sounds as if your "standard" springs are the incorrect length or possibly the rubber packing pieces are incorrectly fitted or too thick.   

Derek

 

 

[AJAS]

Thanks for your confirmation Derek. The rubber collars were bought from the same supplier as the springs and should be standard - they certainly looked similar to the old ones. The fitting seemed ok at the time, so will check again, but my suspicion is that they are either too long or of a different spring rate / diameter to the standard one.

At this moment, looks like a call to the supplier....

Tony

[JochemsTR]

Check the height WITHOUT shocks. What is the compression ratio and uncompressed length you have?

[AJAS]

Hi Jochems

I'll do the check without the shocks - they are presently set on the soft side.

I don't have the technical details, this is from the supplier website

"TRIUMPH TR4A-6 FRONT SPRING SET (STANDARD) THESE ARE MANUFACTURED TO A STANDARD/FACTORY SPECIFICATION. STANDARD RIDE HEIGHT!"

I did a quick check of length against the old springs when I started the job and the new ones were about 1/2" longer - meaningless other than to show they were about the right length. Unfortunately I skipped the old ones at work, so can't compare the coil diameter.

Thanks for the suggestion

Tony 

 

 

 

[StuartG]

Wont the height from floor to wheelarch be affected by tyre size ?

I.E I assume the 27" figure is with original size / type tyres ?

[Rob Salisbury]

You will want a few trips around the block before the whole system will settle down, those ghastly speed humps are perfect for this provided you don't take them too vigorously.

Cheers Rob

[JochemsTR]

Standard Front Springs are 305-310 Lbs and should be around 258 mm.

With 645 Lbs on the Front, you can check whether your measurements make sense. if the calculated compression is lower than your actual measured value, you have an issue somewhere else.

So with 645 / 2 = 322 Lbs. Your spring should compress around 1 inch. --> 232 mm. Make a marking on the uncompressed spring, measure the distance between the markings before and after. This should give you some kind of indication whether your spring is causing the 28" height.

 

[Waldi]

The std  (but PU) isolating rings on my rear shocks were around 3 mm thick; are yours the same?

If I’m correct, 1 mm change in thickness equals 1.5 mm in ride height.

Waldi

[AJAS]

Thanks both. I'm reluctant to take the spring off at the moment, so will first do the other checks mentioned in the next few days. 

For completeness, tyres are 185 x 70 x 15

Don't know the exact thickness of the isolation rings, but they weren't particularly thick - another point to check! 

Here's the gap - I can easily get 4 fingers between the tyre and wheel arch

[AJAS]

[JochemsTR]

4 hours ago, AJAS said:

Thanks both. I'm reluctant to take the spring off at the moment, so will first do the other checks mentioned in the next few days. 

I am not sure what other checks you are referring to. Take one spring out and measure accordingly as I described. Takes about 1 hour. 

[Rob Salisbury]

Hi,

             The 185/70/15 tyres do not stand quite as tall as the original 165HR15 tyres, not much in it but they do exaggerate the gap above the tyre to the wing (been there and gone back to 165 tyres), but you will be surprised by how much the suspension will settle with a bit of on road use.

Cheers Rob

[Malbaby]

I agree with previous comments and doubt that you have been supplied "standard" springs.

They are either too long or are uprated [most likely]

Your supplier should be able to tell you their compression rate....or you could take them to a suspension shop that has a tool to measure CR.

[AJAS]

Hi all. Thanks for offering thoughts and advice thus far.

I have stripped down one side and followed through the suggested checks above. I have the following info:

• Shock absorber removed - no difference in ride height. Shock 10" total extension (centre of bottom eye to between the two top mounting bushes)
• Isolation rings 3mm thick
• Coil 10.25" free length, 9 coils @ 1/2" wire dia 
• Difference in coil height between free length (on the bench) and fully compressed (on the car) 1"
• Difference in lower profile tyre from standard is around 1/4" smaller tyre diameter

Having done further research on this forum, I have found a specification that says 5.25 coils, not the 9 that I have. I realise that spring rate will have an influence on the number of coils, but I don't know the rate info on the new springs. 

I am at a loss......

[JochemsTR]

1 hour ago, AJAS said:

• Coil 10.25" free length, 9 coils @ 1/2" wire dia 
• Difference in coil height between free length (on the bench) and fully compressed (on the car) 1"

This is what I described. 
So you have original springs with original compression ratio

[AJAS]

So it seems, Jochem - thanks for your check suggestion.

But it still sits 1.75" higher than it should and just looks odd! 

I've checked the supplier part number against other suppliers of standard front springs and they all have the same reference number and have the same number of coils....I'm contacting the supplier to see what they have to say...

Thanks everyone for all previous comments and suggestions

[JochemsTR]

You can look for alternative springs which are shorter with a similar compression ratio. Or much shorter but with a higher cr. You can easily do the math….

or…..what I did, I had my springs compressed to meet my requirements. 

[barkerwilliams]

When I bought my car it had lowered springs, not dramatically lower. 

The consequence was it could not take a speed bump at more than a walking pace without bottoming out twice. This also had the result that when I approached a speed bump I slowed dramatically to be able to get over, unfortunately the cars behind were not expecting this and on a number of occasions I held my breath whilst looking in the rear view mirror.

I had to struggle to find genuine standard height springs (everybody wants them shorter, sir) but now the car will take the aforesaid speed bumps (four on one local road) at about 30 without bottoming.

The car is not noticeably different on cornering, indeed after much suspension tuning the car now corners on rails and drives so much better on the badly repaired roads with asphalt chunks missing with the suspension absorbing the impacts without transmitting so much to the shell.

If you do fit shorter springs please ensure the ride height is still within the operating range of the shock absorbers. Bottoming the shocker out before the suspension bump stop is bad but if the shocker tops out it will lift the wheel off the road just when you need maximum grip.

So fit shorter springs if you must but save the ones you remove- just in case.

Alan

[JochemsTR]

Alan, ofcourse.

But in Tony's case, his overall settings are off. Some will settle after a couple of miles, some will not. Why? good question. Maybe the new parts are not upto par. Offset, addition of tolerances.

I would buy Article 661-650 from Moss. Those are the original spec springs. Not very expensive. Check again. When the car still sits at 28" 1/4" , I would have them compressed by 0,7 " --> this gives you around 27" as a new height. You can increase the thickness of the springcollars (0.120 --> 0.325) as the springs settle.

I am sure there is a shop in UK who offers this kind of service. We even have them here in germany.

 

[Z320]

On 3/25/2023 at 3:43 PM, Waldi said:

The std  (but PU) isolating rings on my rear shocks were around 3 mm thick; are yours the same?

If I’m correct, 1 mm change in thickness equals 1.5 mm in ride height.

Waldi

Nearly, 1 mm on the spring are 2 mm on the wheel arch,

1/2“ longer with original spring rate is 1“ on the wheel arch.

Big mistake to give any old original part to the scrap!

Edited March 27, 2023 by Z320

[harrytr5]

Rear springs fitted to the front?

Regards Harry

[Z320]

Front too high with new springs we had here only a few weeks ago, but I can’t find it.

Sadly this forum has a systematic due to car models and not due to problems, for example „front suspension“.

We had that too already……

[AJAS]

Definitely the 'correct' front springs, assuming the part number on the label is correct, as it was still in place.

So just stripped the offside rear suspension - also sitting high - to find, as I suspected, a new spring, also with the part number label still on. Checking that on the suppliers' site, it is a standard rear spring.....here we go again 

[stuart]

Just out of interest who supplied the springs?

Stuart.