Best way to test shocks/struts Bilstein I think.. Un-nerving handling at times
 

I think the shocks are Bilstein (yellow on the rear) and according to their site they last for years.. The car is a '75 911s and it can be a bit frightening to drive - more so lately. It isn't the tyres as I have new F1's on with the right pressures. Changing lanes can be a bit twitchy and if I drive at 60 and slowly swiay the steering from side to side the car feels very unstable - like the back can't keep up with the front and I end up steering in the opposite direction to which I'm moving (not literally but kind of counteracting the action of the car rather than leading it) - it's a bit hard to describe but it doesn't inspire confidence - I have new anti roll bar bushes and nothing loose that I can see - so what is the best way of testing the shocks?????

And can I check the torsion bars in any easy somestic garage way??

And How bout any other bushes...

Any Help Most Welcome before I go out and spend unneccesary cash.. I'd like to target the problem if I can..

Cheers All

T Swedehttp://forums.pelicanparts.com/uploads/frontalley2.jpg

And please excuse my crap spelling..
 

I was rushing to get a beer - the sun is out for once...

Doesn't sound like a shock problem to me. Sounds like an alignment problem. My guess is that you have too much toe out. If you could remove the body and look down at your front tires your front tires should look like this l l Too much toe in looks like this: / \ Too much toe out looks like this \ / With too much toe out each tire is fighting to go in the direction it is pointed which makes for some really twitchy steering. I would check my alignment before I start replacing parts.

Well, if you want to test your shocks you could unbolt the top or bottom of the rears and try to compress them. They should be pretty hard to compress assuming they are gas (I think the Bilsteins should be). My original shocks were gas charged, so if you compress them while not on the car they should extend to full open on their own, but when I pulled mine I could compless them and they would stay there. And they were really easy to compress. That would be a good start on the shocks. Also, if the rear is sitting really high like it often is on American cars that haven't been lowered the rear will sway more than if the car is lowered. And as Kurt said, alignment can do all kinds of things. Also, tires can be very different. Some have much firmer sidewalls than others. I recently changed the 730's on the back of my car for 750's, and it has been detrimental to my handling. Not horrible, but different than it was. I'll have to wear out the tires quick now so I will have an excuse to replace all 4.

I once had the same problem...especially unsettling when doing lane changes..it was the shocks, although at first I thought it couldn't be.

First, however, check toe ( should have small toe-in)..and check ball joints.

---Wil Ferch

I recently redid my entire rear suspension but kept the same shocks. The rear spring plate bushings as well as the trailing arm bushing were in awful condition and the car handled similarly to yours. Once I replaced those bushings, the car started handling like it should.

It's pretty time consuming job because of all the "while your are there" repairs that go along with it, but it will definitely help your handling issues. FWIW, my car is only 2 years older than yours.

Good luck.

Doesn't sound like shocks to me either, but what do I know? I would say that if a shock is 'easy' to compress by hand, then it is junk. I'd suggest looking at alignment issues too, assuming your tires are matched. Mismatched tires very frequently produce the effect you seem to be describing. Like piloting a boat, instead of a car.

Bouncing bumpers also seems to me a poor way of judging shocks. My shocks are currently very worn (I really am itching to replace them), but I do not get the boat feeling. A good test for shocks is to find a road with many small bumps and cracks in it, and drive that road briskly (though not too fast of course). A car with worn shocks will skip around, particularl in turns. That's because the tires are being allowed to leave the road surface. They're bouncing. The job of a shock is to prevent bouncing. Keep the tire against the road. Torsion bars don't have this job. If it were not for the shocks, tires would bounce against the road like a basketball. You see this sometimes on other cars next to you on the freeway. Point is, if your car seems to skip sideways during turns on rough roads, you need shocks.

re the shocks
 

Well thanks for all the advice - I'm not kitted out to do alignment checks however I can unbolt and check the rear shocks to eliminate them - or not as the case may be - I have noticed the car 'skipping' a bit on bumpy bends - one in particular near where I work... I guess to do the alignment I'd have to book it in to a specialist...

Can I easily check the rear spring plate bushes myself?

And I suppose it's harder work checking the front shocks..?

TSwede:

Get your alignment checked 1st . . . can answer alot of ?????

The rear spring plate bushing are shot if the edge of the torsion bar cap (where you can see the bushing) is not centered on the bushing.

Here is a picture of Chuck Moreland's new bushings and cap.

http://forums.pelicanparts.com/uploads/splate2.jpg

Generally if the edge of the cap is sitting on or near the torsion tube, they are in need of replacing.

Cheers all - I have the shocker disconnected and it's behaviour is as follows..
 

The bottom of the strut is disconnected - it is a Koni sport adjustable ( is it safe to assume they are Konis at the front then I wonder)..

Anyway - when I push the shock up with my hand it offers up resistance but it is possible to slowly depress it all the way up - then I let go and it stays there -

It needs the same amount of pressure to pull it back down - someone suggested they should ping back - Fast or Slow?? My neighbour thinks it should stay and the movement of the wheel/suspension brings it back..

Any wisdom or experience on this would be very useful - I'll take a look at the spring plate bushes as well to see if they look centred..

Thanks in anticipation (of a big bill)

Koni shocks are not gas charged so they will stay where you put them one way or the other. They adjust for rebound only.

Can't assume that you have konis on the front. Even if the strut towers are orange, some PO might have stuffed Boges in them . . . ask me how I know this.

right then..
 

... I was misled - I thought the Koni Sports were gas - anyway, they are offering up some resistance, though I can't tell for sure if they're ok, but as the car isn't bouncing and settles level when I take my weight off each corner I'll leave them for now and see what difference changing the trailing arm bushes and the swing plate bushes makes - they are cheaper than the shocks so it's the most economical route - also there is slight play in the steering - I will try to figure if it's the rack or the tie rods/track tod ends - if it isn't the rack I assume I could sort out the problem with a set of turbo tie rods...

I asked about having the alignment checked once before and the Porsche bloke said that If the bushes are worn (at the time I was about to change the anti-roll bar bushes) then it isn't worth doing the alignment as it won't remain accurate - I'll probably change the front torsion bar bushes as well then get the alignment checked - and only then spend money on shocks if there is still aproblem -

Bit of a process of elimination but as the anti roll bushes were so shot I can assume the others are as well..

By the way (Marc)
 

BTW - Marc posted a pic of spring plate bushes - I looked at mine and the bit that sticks out (probably the cap) is not centred in the hole it sits in - it isn't touching the squarish metal plate that is bolted to the body but it's pretty close at the top - I assume this means the spring plate bushes are *&^%*&. What do you all think..

Sounds like the shocks are probably fine then. Bushings and alignment then would be my next guess.