1990 C4 Suspension Suggestions Needed

[AP-123]

This is my first post - thank you for your patience.

1990 C4 - I'm 100% street daily driving on the streets of Los Angeles. Any suggestions for a decent set of shocks or shocks and springs would be greatly appreciated.

I've heard the Bilstein HD's are good but was also told to put M030 springs on. H&R also makes a coil over but that is a more expensive option. I don't want a harsh ride.

Car has 120,000 miles on the original suspension.

[computamedic]

The Bilstein/H&R combination is good (using the H&R Green springs - not the coilover kit) although you might find it a little harsh if the road surface is bad. Eibach also do some suitable springs that are a little less harsh and don't drop the ride height quite so much (Eibachs are -30mm, H&R Green are -40mm).

Don't be tempted to change the shocks without doing the springs too. 20 year old springs are no better than 20 year old shocks!! Paying for a 4 wheel geo twice is no fun.

Regards

Dave

[AP-123]

Thanks Dave!

What about the M030 springs? My mechanic has a pair around that he wants to sell me. Said it would lower the car about an inch but that would be a good thing.

Are there more than one kind of M030 springs? How much are they worth?

Thanks again

[computamedic]

As far as I can establish through PET, the M030 Sport Suspension consisted ONLY of different Boge shock absorbers. There appears to be no different springs associated with the M030 option.

Given that the springs are the cheapest bit of the suspension setup it seems strange to make a decision on used, unknown springs when you could get brand new, known, springs for little difference in price. Bear in mind that rear springs particularly take a severe beating on 911s due to the massive weight on them and second-hand ones could be severely compromised. New ones are, at least, a known quantity.

Regards

Dave

[AP-123]

Thanks Dave - this is good info.

The M030's he has are new, so I just have to make sure they are for my car.

I've heard there are differences between C2 and C4 and for Coup and Cab - but I'm not positive.

Do you happen to know a good place to source them new would be?

[computamedic]

I've done a bit more research into the M030 issue and, according to Adrian Streather's book the M030 option only applied to 1991+ cars. The full kit consisted of a 22mm front sway bar, slightly stiffer Boge shock absorbers all round and progressive, stiffer springs for the rear. The front springs were, apparently, different although with the same rating as standard.

There is a rather vague warning in the book which says "M030 rear suspension components cannot be installed without additional aftermarket engineering on any C4 or C2 manufactured before 1st November 1990". I suspect this is because of the difference in the rear shock mount for the early cars so it's unlikely to affect the fitting of just the springs although you should make sure you get the correct rear shocks for your car.

There are also differences between the US M030 springs and the RoW M030 springs but I doubt that is an issue here.

There are differences between the standard springs for C2 and C4 but aftermarket suppliers don't seem to make any distinction - other than H&R who market the Greens for the C2/C4 and the Reds for the Turbo. PET lists no fewer than six different spring sets for the front (excluding the Speedster) and rear. There IS a listing for the M030 rear spring - which happens to be the same are that used for the Turbo. The springs are all factory marked with a stripe of coloured paint in order to identify them. The M030 rear springs have a green paint stripe.

I didn't initially see the M030 spring because it's only listed in PET for the rear.

Regards

Dave

[dewflex]

By the time you buy coils and struts at all 4 corners, you are into coilover territory, which would give you more options in adjustable dampening, ride height, etc. I know they are expensive, but they are engineered to work together. I just picked up a brand new pair of JIC's for $1700! Don't have them on yet, but I have 15 dampening positions, and can set the ride height wherever I want.

[AP-123]

dewflex - you have a point. But it is another price point.

Called a few other dealers today - they suggested just using the stock springs with the orange stripe. Now they are checking to see if the euro spring is available and if it is also the same orange stripe.

Will let you know - thanks again.

[dewflex]

I would scrounge the classifieds, you are bound to find someone whom moved up to a track suspension and still have their used lowering springs/shocks. Maybe even check with your local mechanics, LA Dismantlers, etc.

[GregB7S4]

Here is what I would do;

Lowering springs (H&R or ROW M030) $300 or so
Koni sport shocks/struts $900 or so
Front M030 sway bar $?
alignment $250 or so

[GregB7S4]

Originally Posted by GregB7S4

Here is what I would do;

Lowering springs (H&R or ROW M030) $300 or so
Koni sport shocks/struts $900 or so
Front M030 sway bar $?
alignment $250 or so

Not sure the rear shocks are available for your car. There is a great article on the C4 from Excellence Magazine article in 1992, it is viewable at

John's 964 Web

Go to reviews tab then search for article titled Wringing out the C4.