MOT Failure - Front Springs

IanHighfield · Apr 9, 2011

Realised the MOT was up and so got a same day booking at Kwik Fit.

All OK except the front springs do not correctly relocate when you lower the vehicle from the ramp.

When raised the springs are shorter than the shocks and become detached at the top mount - this is OK. See picture below.

But when lowered back down the springs do not automatically relocate correctly in to the mount.

The struts are bilstein and the main and helper springs are Eibach - very stiff ! The white top mount is from Jaz - allows different size springs ???

I will get the car over to Tuthills but any clues on what can or should be done ?

Ian

Steve Brookes · Apr 9, 2011

Very odd! Is there any thread left on the lower spring perch to take up the gap? Maybe the springs are just too short or have been cut down?

IanHighfield · Apr 9, 2011

Steve

The complete strut and spring package was fitted by JAZ Wembley for the previous owner, so I believe it to be 'OK' but need Tuthills to take a look.

For reference the specs. on the Jaz invoice are are :-

Bilstein Struts (no reference number to hand)

Eibach Main 180/60/40
Eibach Tender 50/60/20

JAZ also fitted a a set of used Special 60mm top spring mounts

Can anyone explain the Eibach numbering ?

What does the RS have as standard springs ?

Ian

Steve Brookes · Apr 10, 2011

Let us know what Tuthill's thinks because as I said before, it looks odd to me and have certainly never seen the like before. Migtht also be worth posting this on Rennlist to get opinions/help from a wider audience?

Laurence Gibbs · Apr 10, 2011

looks to me like the springs have been "matched" to struts that are too long for the spring combination. Hence when the car is lifted off the ground the struts have more travel than the springs can take up.
The numbers on the springs from memory I think relate to spring rate. The RS uses single progressive rate springs with twin tube shock absorbers at the front and single tube rears. The top mounts on the RS are monoball not rubber as the standard c2.http://e30m3project.com/e30m3performance/tech_articles/susp-tech/springs/index.htm
this might help understanding a little

asjasj · Apr 10, 2011

I don't think this is unusual.....................lots of rally cars would be like this but tend to run a 'helper' spring. It's a very small, low rate coil that sits above or below the main spring and just takes up the slack when on full droop. When the weight of the car is on the damper/spring, the helper spring is crushed flat.

For example....

And in use.....

IanHighfield · Apr 10, 2011

Thanks Laurence and Ade

I had read up on Helper springs and think they may be the answer - Eibach do them in their catalogue.

Got the wheel off this afternoon and I am able to compress the spring slightly by hand and push it and and 'catch' it under the top mount if I want to. The Helper would prevent this ?

I confirmed the spring specs. to be as above post, and the struts / dampers are Bilstein HD or Sport (different sites call them different things) for 964 C2 reference F4-VE3-5277-H1

It could be the springs are too short or they need Helpers - will talk to Tuthill etc. and let you know.

They are of course fine when the car is on the ground !

Iain

IanHighfield · Apr 10, 2011

Here's a link to where Eibach describe this setup.

May just need the top Helper springs.

http://performance-suspension.eibach.com/cms/motorsports___suspension___sport___springs___performance___racing___baja___rally___score___f1___nascar___v8_supercars___btcc_eibach_race_spring_system

Ian

Gazza3501 · Apr 10, 2011

Looks very odd, like a miss-match or the helper spring (as mentioned earlier) is strangly missing. It certainly cant be right like this.

Laurence Gibbs · Apr 11, 2011

One other thing to note and good reason for probably not trying to re rate the springs (unless you want a different ride height). Running the shocks/dampers as they are means they are likely to be running near to bottomed out when the car is lowered back to earth. the piston rod
will travel down past the point it was usually designed to work and the damper simply won't perform at it's best !
I would be inclined to either....get shocks to match the springs or springs to match the shocks or better still a known working package, KW variant 3 , Bilstein Pss9 etc. Tuthills will be able to advise you on what will work with what.
looking at the other pics , it could also be that the springs did once fit but have taken a set or have sagged slightly, less of a problem.

asjasj · Apr 12, 2011

Will be interested to hear the outcome Ian..............

Is your car 'excessively' low in this setup by the way?

IanHighfield · Apr 12, 2011

Ade

It is low, but not sure exactly how low - I would like it to be at RS height so will let you know.

I think from memory it was about 24 1/2 inches from wheel arch lip to ground at the front which I think may be too low.

Ian

Steve Brookes · Apr 12, 2011

For reference, mine is set to RS + 5 mm and I've just done a similar arch to ground measurement which reads 25 1/4 inches.

IanHighfield · Apr 13, 2011

Thanks Steve,

So RS height would look to equate to approximately 25 inches (i.e. 5mm lower than yours).

I am pretty sure mine is just below that, but I know body lines vary and will ask Tuthill to set to RS height using the chassis points to measure.

Ian

h_____ · Apr 13, 2011

Be aware if you set a standard 964 to RS ride height you cant get the alignment settings right on the back, as the RS has more adjustment at the rear. if you fit the RS rear arms, thats fine. Otherwise you will compromise the alignment settings to gain the lower height. Chris at Centre of Gravity can gvie details on this, he's got a set of pictures that explain it well.

Ian, I know your car isnt standard, but cant remember if you've got RS arms at the back?

IanHighfield · Apr 13, 2011

Hugh - had a good chat with Paul at Tuthills and they have taken it to their MOT man to get his opinion on the MOT aspect.

They will then review the setup and we will go from there.

I have the correct RS eccentric rear adjuster that allows you to dial in more -ve camber so I believe we should be able to get RS settings - I have sent Paul all the RS alignment specs fro reference but he already has it - they do look after a number of RS's for owners that also have early cars etc.

Will update more tomorrow.

Ian

h_____ · Apr 13, 2011

ORIGINAL: IanHighfield

Hugh - had a good chat with Paul at Tuthills and they have taken it to their MOT man to get his opinion on the MOT aspect.

They will then review the setup and we will go from there.

I have the correct RS eccentric rear adjuster that allows you to dial in more -ve camber so I believe we should be able to get RS settings - I have sent Paul all the RS alignment specs fro reference but he already has it - they do look after a number of RS's for owners that also have early cars etc.

Will update more tomorrow.

Ian

Cool - nice to see the job done right! [

]

IanHighfield · Apr 14, 2011

Car passed its MOT as is, so well done Tuthill MOT man.

However, the car is as high as it will go, and is approx 25mm 'below' RS height +- 5mm - !!!

So Tuthill are going to make a few calls to Bilstein / Eibach etc. so we can get the correct length and load springs to enable it to be set to RS spec.

Ian

RLambert · Apr 14, 2011

Have you spoken to Steve at Jaz about it, seeing as they fitted them ?

He does the suspension on my race car so knows his stuff. I also have helper spings but when the car is raised on a jack there is a bit of a gap at the top of the spring, they twang back into place when it's lowered back so it's not a problem.

IanHighfield · Apr 14, 2011

Richard

Paul at Tuthills knows Steve and is going to talk to him. The main query is that the car is very low (I love the stance but it is very firm on the road) and the suspension is set at its highest point.

What suspension setup do you have ?

Thanks

Ian