A production car is designed to understeer - it's safer that way.

Part of the process of having the front tyres loose grip, before the rears, is to have the front bumpstops engage before the rears and/or at a higher rate.

We, as self-proclaimed driving Gods, normally get around this, intentional, in-built understeer, by fitting a stiffer rear bar (reducing rear grip), to neutralise the handling.

A stiffer rear bar reduces the independence of the rear suspension - on anything less than a very smooth road surface, that equals a loss of traction and comfort.
If you can use the bumpstops, to get a neutral baseline starting point - you can use less rear bar.

However, balance is personal. On a track day car, once you've changed the bumpstops, you may prefer a larger front bar to get back to neutral, rather than reduce the rear bar. A stiffer front bar would reduce loss of camber on turn and limit front suspension travel.

I don't know why you would need more, than a 20mm adjustable rear bar, on the road - but it's very personal.

£50/$75 for front and rear bumpstops and dust boots. Bumpstops to be on show, to check for degradation, with the dust boot attaching to the bumpstop.

Does that help?

 

Hello,

I was more under the impression that a bumpstop was just protection to keep the car from bottoming out than an active part of the suspension. I stand corrected. It does make sense now that I think about it. You essentially have a secondary spring that is activated under increasing load.

Aftermarket sway bars at least in the US will be interesting. Most were tuned I suppose for a stock suspension, with 22mm through 27mm being common.

 

http://www.superstreetonline.com/how...mp-stops-here/

If you wanted to keep the stock dust boots, the P11-6, on a twin-tube damper, could use the standard rear bumpstop with the smallest section removed. Again, if you wanted to keep the stock boots, on a twin-tube, rather than cut down the front stop, I'd use Febi 27848 - dome side up (in the US search 13189414 which is the GM equivalent)

 

Thanks for the detailed explanation, I've learned something new today. Would the same apply for the red struts with regard to trimming the rear stops?

 

The KYB inverted struts with P11-6's?
No, they wouldn't need trimming, but I would get new, updated bumpstops for them. I think they're £57 a set of 4

peter@pcadynamics.com

 

Yes KYB inverted on P11-6 springs. Will do, is that your contact for bump stops?

 

Only for inverted damper bumpstops.
He designed the P1 suspension, amongst a few others.

 

Thanks, I'll send him some mail!

 

So again, as if I were a small child, why would anyone want to keep stock dust boots?

And if you already have a largish front and rear sway bars, what adjustments could be made to bump stops to lean more towards neutral?

 

Maybe, you've spent, almost, all you can afford on the P11-6 springs? Then, assuming the dust boots (front and rear) and the rear bumpstops are in good condition, you could cut down the rear bumpstop by one section - and re-use. Then, just buy a couple of the febi stops for the front.
I'd spend the extra £50 and get the new, alternative bumpstop set.
Or, maybe, you like the original look under your car? All sorts of differing people in the world.

I assume those who have gone to the expense of stiffer, adjustable, front and rear bars, have now achieved a balance they like. Changing the bumpstops, when changing the springs, should allow them to run less rear bar, for the same balance - which has the benefits already discussed.
My question would be: If they're running lowered springs, what did they do, if anything, with their OEM bumpstops?

 

Ah, gotcha. I figured in for a penny, in for a pound at this point.

The US 2.5 RS came with tinnie-tiny sway bars (19mm/13mm) and such questionable choices as hard rubber endlinks. Consequently, the most popular modification was new sway bars all around (I have 22mm/22-26mm) and better endlinks, even without thinking of lowering the car.

The balance is quite good, with very controlled rotation at medium speed.

But now is the option to increase the absolute grip in the rear while still keeping the same balance. The question is given the other changes, what range for the rear sway bar?

Since I don't know what UK spec GC8 sway bars were, it is hard for me to gauge.

 

I've had quite a bit of interest in the P11-6.

So I'm getting 50 sets made - So, price break - £235 delivered.

Incidently, they're now designated P11 L at Eibach.

 

Nice one! Great news

 

I think the Impreza P1 had a 19mm front bar and a 20mm rear.

I think you'd have fit the springs and bumpstops, and adjust the balance back to your personal taste through the bars.
If the rear bar is adjustable, I might be inclined to start at its softest setting.

 

Eibach have re-designated the P11-6, the P11 L
I've now increased the order of P11 L's to 50.
So, a price break kicks in - £235 delivered mainland UK

twistybits - P11 L
topshot - P11 L
Scooby Wagon - P11 L
piehole1983 - P11 L (NI)
Rob669 P11 L
Sad Weevil P11 L
OBSTi P11 L (US)
Laupy P11 L
Donkey Dave P11 L

2pot WR15 R/T
Scott.T WR15 R/T
qsl WR15 R/T (US)
Geddesk2_2 WR15 R/T (US)
HighRevimpreza WR15 R/T (US)
Eacy WR15 R/T (Denmark)
Scoobyedge WR15 R/T

bonestter P11
Vee P11
Mtb_ed P11
P1 Steve73 P11
rusty&dusty P11
KRob P11
allsop83 P11

 

Well done, good stuff.

 

Hi I'm glad I found this thread on Google while searching for springs. I live in Canada how much would it be for shipping?

I imported a MY98 v4 GF8 sti, would any of the 3 springs improve on rear sag? I don't know much about suspension but I want to get a set since these are rare.

Could anyone recommend one for a daily driver, spirited highway driving, slight lower, and no track? I'm guessing the p11-6? Is it too late to order?

Also how can you tell if its an early or late Bilsteins?

 

Any numbers on the Bilstein dampers? Are any of the following visible?

Prodrive Bilstein WR97/98
2030055120 (7114262M000) 2030055130 (7114261M000) 2220055120 (7104264M000) 2220055130 (7104263M000)

Prodrive Bilstein WR99 professional
F4VE34625M0 F4VE34626M0, F4VE34627M0 F4VE34628M0

There were some Japanese Bilstein variants:

Bilstein/eibach soft 171/140
front pair strut and spring 2000055020
rear pair strut and spring 2000055030
rear pair strut and spring wagon 2000055040

Bilstein/eibach hard 196/168
front pair strut and spring 2000055050
rear pair strut and spring 2000055060

The P11 L (previously P11-6) and the WR15R/T both accommodate the GF8

From your description P11 L would be suitable

PM me an address and post/zip code and I'll check delivery costs. To the US its $120 US - 3-5 day delivery.

HTH

 

Eibach have re-designated the P11-6, the P11 L
I've now increased the order of P11 L's to 50.
So, a price break kicks in - £235 delivered mainland UK

WR15 R/T - currently £290 delivered mainland UK

Please add below, if your dampers are inverted (in) or twin-tube (tt).
If twin-tube, do you want a matched bumpstop/dust boot kit? +£50
If inverted, and you want bumpstops - contact peter@pcadynamics.com www.pcadynamics.com
£62.40 UK delivered - kits for early Bilstein, late Bilstein and inverted KYB.

twistybits - P11 L
topshot - P11 L
Scooby Wagon - P11 L
piehole1983 - P11 L (NI) in
Rob669 P11 L
Sad Weevil P11 L in
OBSTi P11 L (US) in
Laupy P11 L
Donkey Dave P11 L in

2pot WR15 R/T tt +£50
Scott.T WR15 R/T in
qsl WR15 R/T (US)
Geddesk2_2 WR15 R/T (US)
HighRevimpreza WR15 R/T (US)
Eacy WR15 R/T (Denmark) tt+£50
Scoobyedge WR15 R/T

bonestter P11
Vee P11
Mtb_ed P11
P1 Steve73 P11
rusty&dusty P11
KRob P11
allsop83 P11

 

Peter got back to me about the bump stops, hopefully I'll get the order in today/tomorrow for mine. How long have we got to go now 2pot?

 

I think it's about 40 sleeps. Maybe we should get an advent calendar

 

Hi All

Wich bump stops do I want with the KYB AGX?

Cheers

 

Hi
They're twin-tube so, tt+£50

 

Yes please! I'm like a child at Christmas

 

Please put me up for some

 

What would be recommended for Koni Yellow shocks? Standard bumpstops and dust covers?

 

Hi

Twin-tubes with the P11 L, optimally, you should use the matched bumpstop set for £50.

However, if your existing rear dust covers and rear bumpstops are OK, you could cut the smallest section off the bumpstop, gaining you 15mm.
If the front dust covers are OK, use Febi 27848 or Optimal F8-7662 (£15/25 delivered) dome side up, instead of your existing 60mm long front bumpstops.

If you've got buy OEM replacement new rear stops and boots, then that's going to cost £26. I know the link says wagon, but they're correct for classic wagon and saloon.
http://www.spring-loaded.co.uk/prodd...rs~-~AK-735144

So, maybe £41 in total - you might as well have the inherently better balanced, £50 matched set. The matched set also have bumpstops visible to more easily check for any degradation.

HTH you decide.

 

3-5 day delivery - $130 Canadian, to your post code.
The P11 L are arriving in 5/6 weeks. Let me know if you want to go on the list, with or without, matching bumpstops and dust boots.
I will not be collecting any monies, until they are at Eibach UK.

 

WR15 R/T springs arriving end of April - colour change, now orange (ral 2004)
P11 L springs arriving end of March

 

Eibach have re-designated the P11-6, the P11 L
I've now increased the order of P11 L's to 50.
So, a price break kicks in - £235 delivered mainland UK

WR15 R/T - currently £290 delivered mainland UK

Please add below, if your dampers are inverted (in) or twin-tube (tt).
If twin-tube, do you want a matched bumpstop/dust boot kit? +£50
If inverted, and you want bumpstops - contact peter@pcadynamics.com www.pcadynamics.com
£62.40 UK delivered - kits for early Bilstein, late Bilstein and inverted KYB.

twistybits - P11 L
topshot - P11 L
Scooby Wagon - P11 L
piehole1983 - P11 L (NI) in
Rob669 P11 L
Sad Weevil P11 L in
OBSTi P11 L (US) in
Laupy P11 L
Donkey Dave P11 L in
awdftw P11 L (Can) tt +£50

2pot WR15 R/T tt +£50
Scott.T WR15 R/T in
qsl WR15 R/T (US)
Geddesk2_2 WR15 R/T (US)
HighRevimpreza WR15 R/T (US)
Eacy WR15 R/T (Denmark) tt+£50
Scoobyedge WR15 R/T

bonestter P11
Vee P11
Mtb_ed P11
P1 Steve73 P11
rusty&dusty P11
KRob P11
allsop83 P11