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TR4a Front coil spring replacement


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Now the weather has gone all pants again I have decided to try and sort out my slightly lop sided car. The drivers side sits a good inch lower than the passenger side (even without me sitting in it)

So In my mind the spring / springs are tired, I took off the offending spring this afternoon and had a measure 10.250" . I have looked at the various options available and considered the use the car gets and have decided that straight forward "standard" springs is what I need, I'm not in to racing or rallying I'm just happy to get where I'm going.....unless any one can offer a compelling reason to fit uprated springs? Will I get more ground clearance? will I get a very hard ride? Will I be able to shoot round corners like a Mini Cooper?

Whilst dismantling the bits I read in both Haynes and the WSM about removing the bump stop and it's various brackets, Well search as I might I cant find any bump stops, should I?

I fitted all new poly bushes and rubber bits some two years ago during original rebuild and they look just fine.

I will obviously be replacing both springs.

Thanks in advance for all  any advise David

 

 

Edited by david c
poor gramer
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Bump stops are integral in the shocker of TR4A onwards. 

Earlier cars only had round bump stop fitted to the wishbone arm and an oblong rebound stop below the spring pan on the chassis, which has to be removed to get the spring out.

So not relevant to your task.

I chose TT4006 springs that are slightly harder and lift the front of the car by about 1/2" - Helps to stop smashing the chassis front on speed bumps/cushions.

Cheers

Peter W

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Keep in mind that the rear coil springs can also affect the front road height, assuming your car is IRS.

You may not need new springs. Take the other front coil off and measure its free height. You can take the springs to a suspension shop and have them individually tested for compression rate. Do you already have spacers fitted?  If not, an easy fix is to fit a spacer to the spring on the lower side. Or if the test shows one has a different rate, swap them over.

IMHO...do not fit uprated springs on a road car. Use standard or softer.

Edited by Malbaby
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Thank you Peter, that's cleared up one mystery and a little extra ground clearance would do no harm.

Malbaby I had not considered the rear springs might affect the front end. I think for now I will concentrate on the front springs and see what effect that has.

Thanks both for your help and advise.   David

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David, I agree with Malbaby. My car sat low at the right rear and high at the left front. This was after a total rebuild with poly bushes. A 1/2" spacer under the right rear spring levelled both the front and rear. I would measure the distance from the ground to the centre of the wheel arch on both sides, front and rear, and see how the car is sitting. Then you can decide whether the car needs springs or spacers. Putting spacers under the rear springs is generally easier than doing the front. 

Unlike Malbaby, I have fitted heavier springs, with 390lb/in at the front and 470lb/in at the back and Koni telescopics all round. We have done a lot of long trips with 2 people, suitcases in the boot and behind the seats and a full tank. Not sure how standard springs would have gone with that little lot!

Rockie

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Hello Rockie

I have now taken off the other front spring and too my great disapointment found they are both the same length, I understand that is not the whole story as Malbaby says the only way to be sure is to have them both tested........but in my usual "gung ho" style I have ordered a new front set, easier than finding a suspension tester locally and probably not that much more expensive.

I'll put the whole lot back together again and see where I go from there (taking measurements at both the front and back of the car.) It would be nice to think I could get the car level by adding a spacer...........to the rear trailing arm, I am not enjoying the drama of removing / refitting the front springs at all.

I can only assume your Australian roads are rather better than our very tired tarmac, the idea of a firmer ride is not a pleasant prospect in this neck of the woods.

 

David

 

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Hi David, a 1 inch difference is a lot, I used 6mm spacer to correct a difference of less than 1/2 inch. Are you sure the suspension has been assembled the same both sides and the chassis is straight?

Chris

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Hello Chris

Yes one inch does seem like quite a lot, I assembled the suspension myself, so that's one area to check:rolleyes:.

So far as chassis straightness is concerned I can see no particular / obvious reason why it should not be, so I'm going to leave that area ............for the time being and concentrate on suspension bits. if push come to shove I'll put in thin spacers top and bottom of the coil spring?

Thanks David

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Although an aluminium spacers are very light in weight, Malbaby is correct is saying that any spacer should be on top of spring so as not to add to unsprung weight.

Ian Cornish

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Complicated business this suspension malarkey isn't it?

I too believe the new springs to be 320lbs, Rimmers don't give details!

As to the weight of spacers I am sure it's not a good idea to add to unsprung weight can a little thing like an overgrown aluminium washer really make any difference?

Thanks for all your help David

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On 3/5/2019 at 12:22 PM, david c said:

 

I have now taken off the other front spring and too my great disapointment found they are both the same length,

 

You need to measure them under load. If one is softer than the other, the free lengths can be the same yet the loaded lengths very different.

Pete

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Okay Malbaby, got that and will only fit "if required to the top".

Thanks Pete, that makes sense. I will get to the bottom of this new springs should arrive tomorrow I will fit them and see where I go from there.

David 

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David, our roads in Australia are rapidly deteriorating, largely due to the plague of 4WD utilities. The largest selling vehicle here is the Toyota Hilux. As all these things weigh more than 2 tonnes and as road damage rises exponentially with increase in weight, our roads are really suffering, along with our road toll. We went to a funeral yesterday of a young man killed when his 4WD rolled. All too common. I hope that the UK does not follow this stupid trend of using macho off road vehicles as daily urban transport.

Whilst my choice of GoodParts 390/470lb/in springs has been queried several times on this list, I still find the ride perfectly acceptable, and with the Koni shocks it is well controlled. I note that the heavy duty springs sold by Moss are very similar in rate. As I have said here before, the mounting of the springs part way along the front wishbones and the rear trailing arms means that the rate at the wheel is lower than the nominal spring rate. Triumph raised the rate on the rear springs from 280lb/in on the 4A which was way too low to 350lb/in on the TR6. 

I would still be concerned about a 1" difference between the left and right front ride height. I would be checking for chassis problems at both ends of the car. You have not mentioned whether you have checked the rear ride heights. As I mentioned earlier, my car was slightly low on the right rear which caused the left front to be high. Correcting the rear fixed the front as well. These cars are old, and, like their owners, are starting to sag in unusual places.......

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So it's not those monster road trains you have then :D it's blinking 4x4's as far as the UK following the trend....that train has already left the station.

I think 320's should be about right, if Triumph fitted 350 on a TR6 with it's heavier engine......well I assume it was heavier.

The front end of the chassis is in fairly good nick considering the poor old bu--er is over 50 years old thanks to Triumphs self lubricating chassis arrangement.

The back end, well that's another story isn't it.

Should have the whole lot back together by Friday, and hope all is resolved, will post the results.

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I have a vague recollection that the six is not heavier than the four. It is a little longer hence a bigger bend in the tube between the suspension towers and a slightly greater tendency to understeer. The TR6 is a heavier car for other reasons. They never used the six cylinder in tractors so it did not have to be as strong. :lol:

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Well what a difference new springs make! looks like a proper car now, still not perfectly level but now less than 1/2" out which I am very happy with.

The whole front end of the  car must be 2" higher.............I can even get a trolley jack under the chassis. Absolute pig of a job but well worthwhile, so worthwhile in fact that I have moved on the the back end, I can see no reason why the rear springs should be any less tired than the front. Worth noting the new springs have one extra coil in the same overall length, 

Just for my own curiosity I rigged up a test rig to test the old springs one against the other, (proper engineers should look away now)

I took an 8' length of 4" x 2" stuck one end between a pile of pallets and marked the "hinge" point, placed the spring on the floor and laid the timber on top of it also marking the spring position on both the floor and the timber, at the outboard end of the timber I stood an old heavy cast iron flatiron and marked the deflection on the side of a cardboard box. even with such a relatively light weight the difference between the two springs was obvious about a 1/4" of and inch. If I had thought about it I could have / should have done the same with the new springs.

 

Thanks every on for your help and advise with this one, with a bit of luck the back end should be simpler.:rolleyes:

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Dont forget you need to run it round the block a few times to settle before saying for definite the new height.

Stuart.

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I'll bear that in mind Stuart, once I've fitted the new rear springs. Am I right in thinking I may need to adjust the camber as well?

Thank you David

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In theory no but if the ride height has altered considerably then probably yes.

Stuart.

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