Rear Suspension, Se

[Steve L]

Last Fall I posted here, because my rear suspension doesn't do much. Now that the weather is warm again, I started looking into the problem.

When I jacked up the rear end of the car, I measured the distance that the rear wheels dropped as I unweighted them: left side, 1.5 cm; right side about 1.2 cm. That is not much (2.5 cm = 1 inch).

It makes me think that the source of the problem is that the springs are simply too hard.

How can one measure the spring rate? What is appropriate for a 570 kg Westfield with a 70 kg driver?

I don't know how much the springs are already compressed on the dampers, but I will be visiting a friend in the next couple of days who has a spring compressor and then I can take the springs off the dampers.

Thanks in advance for all the help that I know I am about to get ;-)

Steve in Germany

[Martin Keene]

1" of drop sounds about right to me. The dampers will only have about 4/5" of travel anyway.

Springs will be compressed by whatever is needed to achieve the ride height, mine are compressed by about an 1".

Spring rates, 150lb/in would be a good starting point if your changing.

[Paul S]

It sounds more like your dampers aren't long enough. Or, you have the adjustable spring seats set too high up the damper.

I have 160lb/inch springs on the rear, which give a fairly compliant ride, without feeling at all soft.

Have you set the rear ride height properly? Have you got wide track rear suspension without the top mount extensions?

Paul

[andybennie]

Hi

Once you have removed the damper/spring assy from the car ( this must be done with the chassis lifted to relieve the weight from the suspension units and with axle supported) undo the adjustable collar all the way down and remove the spring, you will not require a spring compressor .

Andy

[Paul S]

If the powder coat on the spring is still intact, you may find the spring rate printed on the spring.

Alternatively, you need to find the force necessary to compress the spring 1 inch.

I did this by placing the spring on a jack which was in turn supported on the bathroom scales. I then placed the spring between the jack and one of the garage rafters. Zero the scales, jack the spring up exactly an inch, and read off the scales' scale. This proved to be remarkably accurate, once I'd reattached the roof to the garage

It was only after I'd lifted the garage roof off that I found the spring rate printed on the spring albeit very faintly. My measurement was only about 2-3lbs out.

Paul

[Steve L]

Thanks for all the tips so far. The dampers do have an adjustable spring seat, and it is about in the middle of the thread range.

I had been thinking that I could probably relieve tension on the spring by turning back the seat, but wasn't sure whether I could return the seat to its original position (if that was even desirable) when turning it against the force of the spring.

What really surprises me is that your suspensions only have 1 inch drop. I would have expected more. Do the dampers have more travel when you are driving over bumps? I first decided that I had a problem when I  litteraly climbed up on the boot, held on to the roll bar and bounced around with my 70 kilos. The only up-and-down motion came from tyre deformation, non from the shocks. At least, none that I could see.

[John Loudon - Sponsorship Liaison]

Is this a live axled car? If so, the early cars shock absorbers were a little short. 15" open length items work well with something like 120 - 130 lb springs of a length to suit.

John

[DavidR]

What really surprises me is that your suspensions only have 1 inch drop. I would have expected more. Do the dampers have more travel when you are driving over bumps? I first decided that I had a problem when I  litteraly climbed up on the boot, held on to the roll bar and bounced around with my 70 kilos. The only up-and-down motion came from tyre deformation, non from the shocks. At least, none that I could see.

I would expect at least an inch of deflection with a driver onboard and another inch with a passenger so giving between 2 and 3 inches of drop from normal running.

It sounds like the springs are way too strong or it's seized up somehow.

David.

[Steve L]

Okay, I will be printing this out and working on the problem for a day or two. Will report back with more questions or a big thanks.

And by the way, yes, a live axle. It was built in 1991 in Germany. I am not sure how much space there is between the wheel and the wing. I will refit the wheel and measure the upper limit before I make any changes to the ride height.

Steve

[Hammy]

I've got 120Ib/in on the back of mine. There is not much movement when they are unloaded, I expect they probably reach the fully opened damper position -they can't be allowed to open much or the axle will hit the chassis rail that runs under it. 1" doesn't sound too far off.

With the dasmpers on their softest setting you should be able to  bounce the back of the car up and down. if its still rock hard you've either rock hard springs or a seized damper. my car origionally had something like 160ib/in springs -I took the car to someone who knows and had them changed and everything setup -seems to be one area where expert input helps and worth considering...

[Darkspeed]

Are you sure it's the springs and not just that the dampers have been set too hard?

I would wind the damping adjuster all the way back so no damping and then see what the deflections are.

Cheers

Andrew

[Steve L]

Well, I haven't got to my friend yet to take the springs and dampers apart. But to answer a few questions you all have asked:

The first thing I did was to set the dampers to the softest setting. No change, no compression.

I too thought that the springs must be too hard or that the dampers had seized. I was at that point last fall when I last posted here.

Most replies suggested that dampers probably don't seize. As I raised the car I also saw that the dampers had at least 1.5 and 1.2 cm travel, so they cannot be competely seized. (Is there such thing as partially seized?)

Now I am down to springs as a likely problem.

Here is a bit of info that I got from a German acquintance, which he said comes directly from his Westfield documentation:

SPRINGS AND SHOCK ABSORBERS

Use minimum 1 5/8 inch diamter "coil over" shock absorbers with adjustable spring platforms. Front shock absorber length must not be less than 8 3/4 inch with the bump rubber fully compressed, and not more than 12 3/4 inch when fully extended. A closed length of 10 inches when in contact with a 1 1/2 inch bump rubber is ideal.

Ideal rear shock absorber lengths, both models, are: closed - 11 inch when in contact with a 1 inch bump rubber; fully open - 1 1/4 inch.

Proven springs are: front 220 lb/inch x 9 1/2 inch. Rear SE - 90 lb/inch x 11 inch long. Rear SEI - 170 lb/inch x 10 1/2 inch long.

I am quite surprised: 90 lb??? And you guys are driving around with 120-150 lb/inch springs? Something seems to be way off.

Yours, Steve

[Hammy]

Try a posting on the Westfield tech bit. 90ib does sound soft, but the factory will have the correct standard answers

[chazpowerslide]

I run ally bodied AVO dampers all round on my Narrow SE.

The norm is dampers that (measured between the the centre of the mounting eyes) are 14" fully open and 9.5" fully closed on the live axle SE.

I believe that some cars have been fitted with dampers that are 15" fully open and 10" fully closed on the rear, however the length of the body on the longer damper would typically be 1/2" to 1" longer.

You may have an issue getting the ride height low enough with enough bump travell in the damper without it bottoming out or at least running on/too close the bump stops.

You are effrectivly loosing the same ammount of bump travel as the increase in the damper body length with the 15"/10" damper.

You may also find that with a 15" damper you'll need excessivly soft/shorter springs to get the ride height right.

I'd stick with the 14" open and 9 1/2" closed dampers at the rear.

I run 180LB springs on the rear of my SE set up for fast road and track work, I've moved up from 120lbs springs initially, (they were way too soft and the car bottomed out frequently) to 140lbs and then to 160lbs  before settling on the 180lbs.

With this set up there is about 1/2" sag in the rear with me sat in it (a further 16 stone) the ride is pretty good and works for me.

Somewhere between 150lbs and 200lbs would I rekon be the norm for an averagly heavy SE with an averagly lardy driver.

With the ride heights and corner weights correctly adjusted the adjusting collar on the damper ideally want to be in the bottom 3rd of the adjusting thread.

HTH

Chaz.

[Paul Ash]

Apologies if I'm jumping in late here, but which dampers are fitted?

If they're the old Yellow Spax dampers as originally fitted, then these are most likely the problem. The adjusters were notoriously useless and although they may turn the valving is most likely siezed.

remove the dampers and check them with the springs removed.

If they're knackered then replace them with something far better like AVO's