I have just ordered a set of Eibach lowering springs (25mm lower) for my SW20 on Bilstein shocks. How can I decide whether I need to revalve the shocks? My first instinct and after speaking to a mate at Goodyear is to just fit them and see how it drives before doing anything drastic, what do people reckon?

"Eibach lowering springs (25mm lower)"
If you are talking about Eibach Prokits, although they advertise one inch drop, you probably won't get anything like that.
So if you have the stock Bilstein sealed strut/shocks they should be fine if there is no sign of oil around the tops.
 
On my car I found that Prokits ride only about 5mm lower than stock 92+ springs,
 
Manufacturers advertised drop can be a bit dodgy because they often seem to compare their product to brand new '90 model springs that are about 3/4" lower  higher than 92+ springs anyway.
Also your old 20 YO springs have sagged as well.
 

hey Pat
I've got Eibach Pro Kits in mine and AFAIK the shocks (Koni) haven't been touched. Feels great over bumps at high speed too, totally stable and planted.
One complaint/observation though, I heard the Koni shocks have 'digressive' damping so the back end does feel a tad floaty with progressive springs such as Pro kits.
 
BTW: If anyone knows of off-the-shelf Linear springs for the SW20 rear (NOT coilovers) please yell out...

Thanks for the replies. I thought the 92 cars were lower not higher than the earlier 90 cars? Mine runs particularly high and I assume they are stock but maybe not, the car was used as a tarmac rally car. Josh did you notice much of a drop with the Eibachs? I reckon you would need to go custom for the linear springs.
 
Are you going to Wakefield in January?

Ha ha sorry.  I got that wrong. I meant to say that '90 model springs are about 3/4' HIGHER than the later 92+ ones.
 
I also found that with the Pro Kits the car was lowered a bit more on the rear than the front.
 

stuka

Thanks for the replies. I thought the 92 cars were lower not higher than the earlier 90 cars? Mine runs particularly high and I assume they are stock but maybe not, the car was used as a tarmac rally car. Josh did you notice much of a drop with the Eibachs? I reckon you would need to go custom for the linear springs.

Are you going to Wakefield in January?

No probs mate - the springs were already in there when i bought the car so I couldn't tell you about the drop sorry.
However, I don't know whether they sagged or what, but they were on average 5-10mm too low for REGENCY specifications here in SA. So I had to get them re-set/lengthened.
 
Wont be able to make it in Jan unfortunately, just started a new job (no leave).
 

ok thanks, will see how it goes