Suspension question - too firm?

[MikeSid]

1980 SC. Ride is way too harsh. Every crack in the road sounds a "thunk" like the front suspension has zero spring to it. What is the issue here?

I don't know much about torsion bar suspensions. Can a torsion bar lose it's natural ability to untorque itself like a spring being compressed to the point that it won't rebound????

Is this a consequence of improper lowering? Car seems to ride slightly low, but not in an unsightly way and no driveway clearance issues.

Or am I waaaay off and I have some other suspension issue?

Any advice?
Thanks in advance.

[jluetjen]

First question(s) -- what do you have? Do you know what T-bars are in the car now? Did you just buy the car or did you just notice this about how your car felt.
Second question -- how low is your car? You can give us an idea by taking a tape measure and measuring the distance from the top of each fender cut-out to the road.

[MikeSid]

I noticed the issue when I acquired the car and I am just now getting around to dealing with it. So it didn't just happen recently. It has been in this condition for the last year.

I don't know what T bars are in the car. Is there a way to tell without removing them and putting a caliper on them to measure OD?

I will get a measurement of the ride height from street to fender lip. Might not have this until tomorrow at which time, I'll bump the thread.

[tobluforu]

How low is the car? You can lower the hell out of the front end to a point where the shocks don't do a damn thing.

[cowtown]

What color are your shock absorbers? You can look in the rear and see if the shock body is painted black, red, yellow, etc.

[MikeSid]

I think they're Bilstein struts - green - but I'll have to look again.

I wasn't thinking of this as a strut/shock issue. My understanding is that shocks keep the car from bouncing endlessly on the springs. I am thinking of this as a "lack of spring" issue. So I'm confused why the type of strut would make a difference. But as I said... I don't know much about torsion bar suspensions.

In any case, I'll get some more infor on ride heigh and current suspension components and post back.

[cowtown]

My thinking was that stock springs with very firm shocks give the poor ride quality you describe - I made that mistake 6-7 years ago with Koni Yellows and stock torsion bars...the shocks can definitely affect harshness, but you also need to know what t-bars you have in there.

If your car is excessively low, it's also possible that it's bottoming out and hitting the shock bump stops. But from your ride height description, that doesn't sound like the cause either.

[MikeSid]

It's not excessively low, but hitting the bump stops is what it feels like.

If that is the case, is there a way to improve the ride without raising the ride height? It's not too low and I kinda like the current height. Are larger t-bars the solution?

I'll get more data. Thanks for the guidelines so far.

[Jdub]

Mike:

If this is your first 911 then you may simply be experiencing 911 suspensions. I was pretty blown away when I first drove one, and believed it far too harsh: like a skateboard was my thought at the time.

That said, you have got to mine all the information you can about the prior owner's work on the car. Find the guy and ask him all the questions you can. Then lay it all out in front of you to see what you have.

Finally, I'd say that your car simply has a tired suspension. That is to be expected after all these years. I just finished a total rebuild on my '78SC and the difference is incredible. I put in "harder" components in shocks, tbars, and bushings, but the result is a smoother-riding car that is far less harsh than before the rebuild. That's what makes me think your car is just tired.

John

[Tspringer]

I think most folks who have a ride that they feel is too harsh attribute it to being too stiff. I disagree. I think its usually more an indicatore that something is out of synch. Shocks and springs need to be matched. Very stiff springs without a shock to match can result in a very poor ride. The same can result from it being the other way around.

I just finished a total front and rear suspension rebuild on my '69 911S. The car is lowered, about 24" front and 23 3/4 rear right now (due for more adjustment when its corner balanced and aligned).

My car is light, it probably weighs about 2000lb. It has 22mm front and 28mm rear torsion bars with custom valved bilstein shocks. It also has Smart Racing Products front and rear anti roll bars, monoballs for the front struts and rear control arms, poly bronze bushings, a strut tower brace and the front struts have raised spindles and it has turbo tie rods. You would think that a car with this setup and being very light would be VERY stiff....

Nope. It actually rides very nice. You do feel the bumps, but the shocks dampen them out very smoothly. I have been pleasantly surprised at how good the ride actually is. The steering is now razor sharp and gives amazing feel. ITs a hoot to drive!

In your case, I would first suspect you have one or more shock frozen or bound up. Perhaps it is a bump rubber yoru bottoming against, but at your ride height I doubt it. I also doubt its has anything to do with the torsion bars. Shocks.... a good bet.

[Zeke]

All of the answers so far have been spot on. There surely is a problem of some sort. However, tires can make a big difference, especially if yours are on the last 3rd of their life. I wouldn't go out and buy new tires w/o checkning into the problem, just know that when you get the thing dialed in, new tires will simply make it even better.

[raceman]

Zeke beat me to it,what`s your wheel/tire combo? and more importantly what is your tire pressure right now?l friend who had just bought a 73 E asked me what he should fill his tires to after we`d spent the day detailing and enjoying refreshments.l jokingly answered "75lbs,just like the manual says amigo" well,he put 75 lbs air in the tires! The next day he had some questions about suspension firmness...l felt pretty bad about it.

[MikeSid]

I honestly thought about tire pressure the other day and I'm sure if I let a whole bunch of air out, the ride would improve some, but that's clearly not the sole problem. Based on the answers so far, I'm beginning to guess it's worn bushings and/or strut inserts.

[911pcars]

Don't guess. It'll just cost you more money.

I don't think it's worn shocks or worn bushings. However, it might be a shock that's lunched; but to start, measure the ride height and let us know what those specs are. Measure the tire pressure and let us know. What kind and condition are the tires? Let us know. Otherwise, we're all just guessing.

Sherwood

[MikeSid]

Okay, I got some more data. Hopefully it's useful to someone out there.

The ride height on the passenger side is 25 inches from ground to fender lip. It's 24.5 inches on the drivers side.

The struts appear to be stock Bilsteins.

The torsion bars show no evidence of being changed out, so I would get they are also stock...19 mm.

Tire pressure is 40 psi.

If you try to bounce the car manually with hands on the fenders, it's very difficult to get any movement at all.

Any thoughts?? Anyone???

[aigel]

I think a lot of you guys are over analyzing this. I give you my word, 98% certain, your shocks are worn beyond all recognition. I had the same thing on my car. 150k mile 81SC. Unless you have records of the front shocks (strut inserts) being changed in recent years, it is time to do so. That will give you a chance to take a look at the torsion bars that are in there too.

I find that strut inserts are usually not changed much, since it is a rather expensive job if you have to pay a shop to do it. I got my car all worn out, I am sure the guy that sold it was quoted 2k for a complete supspension overhaul. That's probably when he cut the car loose.

George

George

[aigel]

PS: That fender measurement indicates that your car isn't lowered into the weeds.

[MikeSid]

That's sounds reasonable and pretty likely.

Any idea why the difference in ride height from one side to the other? Simply a matter of the driver's weight and a frequently empty passenger seat?

[911pcars]

Worn shocks should have little resistance unless there's little fluid movement from internal damage. On the other hand, heavy duty or Sport Bilsteins might tend to be a little stiff. You either have damaged shocks or very stiff good shocks.

40 psi is a little high, although it shouldn't result in the symptoms you describe. Try 32/34. How about the tires? What kind? Good shape? Any front end collision damage?

Sherwood

[KobaltBlau]

Originally posted by aigel
I think a lot of you guys are over analyzing this. I give you my word, 98% certain, your shocks are worn beyond all recognition. I had the same thing on my car. 150k mile 81SC

aigel, Just curious, what brand shocks were replaced? Boge?