mazdaverx7

I want to buy new shocks for my 84, which is a base non Z51 car. I was thinking about buying some new Bilstein shocks and thought I could firm up the ride by buying the Z51 shocks over the standard non Z51 shocks. Are the differences between the two just shock valving or do the Z51 shocks have different sized mounts and hardware?

WVZR-1

Hardware would be the same. I would think an '84 with "base" Bilstein might do well BUT if you did the Z51 spec they would be likely an easy sell if you didn't care for the results. I believe one might need to consider at this time the Bilstein is likely a "generic" spec and NOT a GM spec for the '84.

LongBeachC4

Same mounting, the Z51 shocks are valued for a stiffer spring.

QCVette

I was interested in this too.

When I was checking for a '95 I found the Z51 is a B8 type and the others are a B6 type. The only difference I found on the Bilstein's site was that the B8 type works with a lowered suspension and less travel. On another page they said the B8 works with stiffer springs and sway bars.

The '84 listing shows the B8 for the rear Z51 and a 4600 for the others. (I only found a B6 for the fronts).

On a '94 I used the Z51 Bilsteins on a base suspension and I liked the resulting feel and handling. On my '95 it has the original Delco/Bilstein's on the base suspension and it is a lot softer. The '95 springs are softer than the '94's so I suspect the softer feel is due to both the springs and shocks.

The thing I can't find is anything that shows the damping rates for the two types. I don't know which shock has more (and how much) damping force (in rebound and compression) than the other (which is stiffer) to decide which one I want.

Does anyone have actual damping specification data for the two shocks to compare?

milsurpman

Considering your spring rates are very similar to 85-87 z51. You have a very slightly less stiff front spring then 86,87 z51(front same as 85 z51) with more rear spring rate then all later 85-87 z51. If I owned the car. I would most definitly get a z51 shock which is better matched to your spring rates.

mazdaverx7

I really appreciate all of the info!! Sounds like the Z51 shocks would bolt up and work fine.

WVZR-1

I mentioned "generic" and I believe that very likely all of the "service" Bilstein shocks have become somewhat "generic" in manufacture. I doubt the service product is valved to match OE.

The applications you mention pretty much substantiate that.

QCVette

I agree that the current ones Bilstein offers are probably not the same as the original equipment, but I would still like to find the damping rates to compare the B6 to the B8 in the current offerings.

WVZR-1

I don't believe there are any differences in the dampening rates and Bilstein seems to actually mention that in maybe a "round about way". They only mention a "shorter stroke" for the B8.

There .de FAQS page seems to answer substantially more questions than the US - If you were actually interested I'd make "the international call" and bypass all of the US contacts. I'd have specific Bilstein numbers available to offer up.

http://www.bilstein.de/en/products/search-service/faqs/

I would also use the .de catalog to have that conversation. You might find the .de catalog interesting when it comes to "applications" - you need to watch for production dates. It is interesting though. In the .de catalog there are NO B8 applications that I saw for the C4 BUT interestingly enough there are applications for the Cruze and even a B14 for it.

http://www.bilstein.de/downloads/catalogues/

QCVette

I was looking at the .de pages as well. They have more info than the US sites.

I think you are right that to find more specific answers the .de source might be the best one to ask.

Thanks.

WVZR-1

Sometimes it's much easier to "back-door" information. This might be an interesting call! One fellow has used them and was quite happy according to his last remarks. They turned them around quickly and inexpensively I thought for the FX3 - I'd think they have substantial information available.

http://deltavee.net/

PLRX

Yep, buy the Bilsteins HD, and you will be in business.

QCVette

Sorry to bring back an old thread, but I am getting ready to buy some new shocks and found some info on the Bilstein HD (non Z51) and SP (Z51) for comparison.

I searched for my '95 Corvette and found length and damping values by part number for these shocks.
**The only length difference between the HD or SP is the compressed length of the front shocks. The Z51 has more travel and can go slightly lower.
**The damping rates are quite different. The Z51 rates are about twice as firm in both jounce and rebound.

For me the choice is easy. I will go with the Z51 shocks on my '95. I liked them on my '94 and was investigating it to see the differences. I like a firmer ride.

HD (B6) Front (non Z51) 24-020534
Length Min/Max 10.18" / 13.56"
Damping Jounce/Rebound 106 Nm/ 76 Nm

SP (B8) Front (Z51) 24-184861
Length Min/Max 9.43" / 13.56"
Damping Jounce/Rebound 228 Nm/ 261 Nm



HD (B6) Rear (non Z51) 24-020541
Length Min/Max 9.61" / 14.69"
Damping Jounce/Rebound 134 Nm/ 114 Nm

SP (B8) Rear (Z51) 24-184878
Length Min/Max 9.61" / 14.69"
Damping Jounce/Rebound 222 Nm/ 222 Nm

Cliff Harris

I can't speak for other years, but my recollection is that in 1986 the base shocks were AC Delco and the Z51 shocks were Bilstein (which is what I have).

I'm pretty sure the main difference is that the Bilsteins are pressurized with some kind of inert gas (nitrogen?) to help prevent foaming of the oil in the shock under hard use.

Related to this, I looked into having Bilstein rebuild my shocks a few years ago. They're located in San Diego, so they're not very far from me. I found out that new ones were only $10 more (per shock), so I bought new instead.