Rear Suspension, ride height

[MarkS]

I know this has been visited before, but I'm still looking for a solution..

I recently had new shocks and springs fitted to my series 1. This has resulted in the ride height being increased by at least 2 inches. I've read that new replacement springs are often longer, or stiffer than the originals. But the ones I have fitted just seem to go beyond any acceptable change in ride height. (see photo)
Does anyone know what are the correct size of rear springs in terms of length/ steel thickness/ compressability etc. so I can check what I should have, with what I've been sold.

[malcolm]

Can you show a picture of the car from the side? Might help assess the height?

[MarkS]

I've taken a picture of the rear of the car because it best shows the negative camber of the rear wheels, caused by a high ride height. Like I said, its 2" higher than what it's supposed to be.

[mgcjag]

Hi Mark...As you are aware there is no specified rear ride height for S1/S2 cars AFAIK....that said quite a while ago i asked on the forum for members to measure from the lowest lip on the IRS base plate to ground.....most came at about 7.25-------7.5in....so this is a good start point.....i currently have my shocks/springs off the car if this could be of use....they are boge/sng springs....as sold for all S1/2 models...on my S2 2+2 the rear measurement is 7.25in...im in Ludlow if its any help your welcom to come over to look at shocks/springs or i can photo/ measure..all the best...Steve

[mgcjag]

From the photo it looks like you have pos camber..top out....Steve

[MarkS]

Hi Steve,

Thanks for your help. Yes, I did read your original post of ride-height, and I measured mine which is a little over 9". Which is why I said that mine is riding 2" too high.

I could really use some help with the length of the original spring (I've gone and stupidly thrown mine away).I understand that ride height will be determined by compressability and length of spring. I heard that the original (red) springs have a compressability of 220 lbF/inch. But I can't confirm that without measuring the dimensions with a vernier. (and of course, original springs will be tired, and a bit rusty, so it won't be that accurate)


Now then, after market springs are 280mm in length AND (I heard) had a compressibility of 300lbF/inch. But I can't confirm this... So, I wondered if anyone could shed more light on this...?

[mgcjag]

Hi Mark...from the Jag service manual

[mgcjag]

Hi Mark...just to add..its not just the springs that set the ride height but also the shock perches.....the distance from where the spring sits top and bottom to its mounting point.....As mine give a known ride height of 7.25 in it could be worth you comparing.....What shocks do you have.....Steve

[MarkS]

Steve,

I have Gaz shocks which are adjustable for ride height, and they are at their maximum position for lowering the ride height.
Thanks for the data. Now all I need is the OD.

By the way, is this spec from the FSM for Series 1.5 4.2 or is it the early and later 3.8s..? The reason I ask is because I found the same data on the JagLovers forum where the OP said he didn't have the data for the 4.2, which would be different. He, incidentally worked out the poundage as 205 and 190 (much less)

[mgcjag]

Hi Mark.....data from 1st section in Jag manual..so 3.8 section.....other sections dont show a change..so dont know...would help if you try to put your name and car model in the Signature area......I would also double check your shocks with the supplier.....problems with springs are not usually 2 inches.....where are springs from...Steve

[MarkS]

The springs were sold with the Gaz shocks. They were specific for the series 1.5, so they should be correct....

I won't be the first to complain about excessive ride height after fitting new springs from specialist parts suppliers. The springs they supply are not like the originals. Barrats show one with a different free-length. The diameter of the wire is also different.. all leading to a different poundage, thus ride-height.

Next week I will check with spring specialist.

[MarkS]

Steve, why did you say, 'problems with springs aren't usually 2inches...?

[mgcjag]

Hi Mark...I dont think i have heard of anyone with 2in extra hight with just a spring problem.....you have gone for an adjustable after market option so you cant just dismiss the shocks......you have mentioned S1.5 twice now.....but you car is C reg...1965? S1?

[andrewh]

I think some more detailed photos would be helpful, from the side, from underneath and preferably with one shock off the car. Perhaps you have been sent springs off another model by mistake?

[Simonpfhc]

Hi Mark,

A while ago, I started a whole thread on this exact subject. Have a read through as it will give you a lot of info on standard and aftermarket springs:

http://forum.etypeuk.com/viewtopic.php? ... ND+springs

Cheers

[MarkS]

Hi Simon, Thanks very much for that.. wish I'd seen it before..!

-anyone want to buy a set of springs?

[abowie]

Perhaps you have been sent springs off another model by mistake?

Exactly. The replacement springs are not suitable for E Types.

Put your old springs back on and throw the new ones in the bin.

[MarkS]

If only i could..

[PeterCrespin]

The positive camber looks exactly like a car with normal springs that has been lowered off the jack to the floor and not yet driven. Had you driven it before the photo?


For a 2" rise in ride height, identical rate springs would be less than two inches longer than before.

[MarkS]

Hi Peter,
Yes, I have driven the car about quite a bit.

For a 2" rise in ride height, identical rate springs would be less than two inches longer than before.

I agree that the relation between length and ride height is not a linear one, (mainly because of the angle from the vertical, (pythagoras)), but also because the angle must effect the loading on the spring.
Having said that, I believe the rate is far more important, and, (in the formula for stiffness/rate) that is largely governed by the thickness of the wire.