I don’t post often (nine times out of ten I get my info from the archives) – Maybe someone can advise me on this one…

I have a 90 C4 with 113k and I have recently noticed that the ride has become much harder (especially when it’s been sitting for a while) then it gets a little softer after the first 5 miles or so. I didn’t think much of it until yesterday when I had my son in the back seat, when I walked around the car I noticed it was sitting much lower on his side (he weighs 85lbs). Once he got out the height returned close to normal. Though all shocks should probably be replaced I am looking to do the rears at this time.

I have read through the archives and I’m a little confused about which options work if I want to “replace” and not necessarily upgrade – I am very happy with the how the car performs and its height.

I see that the original Boge are available and they are very inexpensive, however if I change my fronts (maybe next year) the Boge price is astronomical. It seems that the next logical step (if I want to keep my front and rear the same) would be to go with the Bilsteins.

1) Are there any problem using Bilsteins with stock springs (front or rear)?
2) Is the rear shock replacement project a DIY project and if so, is there documentation around?
3) When I do my fronts, will it require an alignment?

Thanks in advance -

 

1) Are there any problem using Bilsteins with stock springs (front or rear)?

Not sure. When I installed my shocks, I changed to H&R lowering springs.

2) Is the rear shock replacement project a DIY project and if so, is there documentation around?

DYI? Yes. Its not too hard. See http://porsche964.co.uk/technical/jclowering.htm

3) When I do my fronts, will it require an alignment?

Yes. When you change the front struts, you need a full alignment. Note: You will also need to corner balance the car too. When you change the shocks, you have to remove the springs from the shocks, which then invalidates the corner balancing adjustments.

 

I changed to Bilsteins. The car is a 1989 and only had 5000 miles on it at the time (1 year ago, long story). Anyhow, the car rode hard and still floated before I changed. After, all is well; it feels like a modern car. The Bilsteins can be installed in your own garage, but then you will need an alignment. You do not need to change the springs. I would recommend that you take care of brakes etc when you do this since car will be torn apart anyhow. (brake lines, rebuild calipers, paint etc.)

The total cost to hire a garage to buy install and align front and rear Bilstein HD was about $1800 in Metro Detroit area by a well regarded private garage.

 

Thanks - all good info.

If I do the rear (only the rear) do I require an allignment?

 

Replacing the rear shocks only will preserve the wheel alignment but you will still need to redo a corner balance.

 

Fronts give far more bang for the buck. Why not do them first?

I did all four, Bilsteins and kept the stock springs. No complaints - nice ride even on bad Atlanta streets, and handling is impressive. I am not sure I would want anything stiffer or lower for street use. As it is, I was faster in my 1986 300 E Mercedes when curves have washboard surfaces. The Mercedes tracked fine, but at the same speed the 964 would bounce and depart the line.

 

I just started a front and rear shock/strut/spring replacement. I may also do some bushings and such while I am in there. I have removed my front right thus far. So far this seems pretty straight forward. After I make sure I can put it all together again I will shoot some video of the other side.

If you do the fronts (I recommend it) be sure and order all the plastic bits mentioned by ducnine in his DIY. Those things are hard to remove from the struts as they are brittle with age. I am really glad I followed that advice.

 

Be sure you get the old style shocks. There was a change over on the 91 cars.
MisterRisky you havent had any fun yet. Wait till you try and break those rear lower shock bolts lose

 

I went to Home Depot and got a 36" steel cheater bar. I think they call them "water pipe" although I have never used them for that purpose. My wife will know I am to the rears when she hears me yelling from the garage "who's your Daddy? Who's your M***** F****** daddy you *** engine **** slot car. " I'll be sure and record that part.

 

 

she will hear the BANG when they do break lose It will scare the crap out of you

 

You don't need a corner balance - the factory manual says to just get the ride height set correctly, no need to corner balance with scales. That will save you a decent amount of money if you're paying someone to do it - for a street car I think corner balancing the suspension is a waste. If you're in spec with the factory manual's heights, you'll be good to go.

 

PM sent

 

I'll factor a new pair of pants into my price projections. When I removed the rear axle nut I had a similiar experience. I had to explain it to my wife least she think I was on the edge of incontinence.