Suspension Refreshes

kevinb34322 · 02-25-2016, 07:48 AM

So I recently purchased an 86' 911 Carrera Cabriolet and it is my first foray into the world or Porsche. Overall the car is in great shape due to low mileage (under 40K) but does have some items that need some working through. I've already gone through the shifter bushings and adjustment process which made a massive difference as one of the bushing was busted in half and an overall adjustment was needed.

My next area to tackle is likely going to be the suspension, as it appears that some of the bushings look a little dried up on the lift. The car tracks perfectly with hands off the wheel, however it feels as though it is stiffer than it should be over small bumps. Any recommendations as to where I should start with a refresh to maximize the reward for dollar? I'm not trying to get it to ride like a caddy or anything, just how it should be riding factory.

kevinb34322 · 02-25-2016, 07:53 AM

Forgot to add the picture of her.

SoCalSK8r · 02-25-2016, 08:43 AM

Haha, I had the opposite problem. My 84 with 50k miles felt too mushy and unpredictable. A complete refresh with some upgrades made a world of difference, beautiful car btw!

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Joe Bob · Joe Bob's Garage

Adjustable sport Koni shocks would do the trick, adjust to your optimal settings.

darrin · 02-25-2016, 09:14 AM

Quote:

Originally Posted by Joe Bob

Adjustable sport Koni shocks would do the trick, adjust to your optimal settings.

agreed, sounds like underlying issue is worn shocks, not worn (loose) bushings.

tonythetarga · 02-25-2016, 09:24 AM

Welcome and congrats on the '86. I had 3 86's over the years, two coupes and a Targa. You will learn that Porsche 911's are typically stiffer than normal cars because they have torsion bar suspensions and not coil springs. Bushings won't change that. The adjustable Koni's may work but you have to know what strut housings you have, Koni's may not fit. Adjustment will be slight and only really adjusts damping. The torsion bars are the 'spring'.

As for other suspension parts to check or replace, you want to look at the rubber front strut bearing at the top of the tower. If you're doing shocks, swap in new bearings. The sway bar bushings should be swapped out and is a DIY. Rears are easy but the fronts can be tricky.

If you have records on the car, you may learn that bigger torsion bars were put in and that could be why it's stiff. If they're stock, then downsizing to smaller diameter isn't a good suggestion. You may have to live with it or look at tire options to soften the ride a bit. If you intent to do a full a-arm and rear spring plate bushing refresh, look at Elephant Racing parts sold via Pelican. Good factory replacement rubber or their polybronze aftermarket. The polybronze will tighten things up however. Otherwise, just enjoy the car.

Joe Bob · Joe Bob's Garage

Taller tire profile will also give you a softer ride.....

kevinb34322 · 02-25-2016, 10:43 AM

Quote:

Originally Posted by tonythetarga

Welcome and congrats on the '86. I had 3 86's over the years, two coupes and a Targa. You will learn that Porsche 911's are typically stiffer than normal cars because they have torsion bar suspensions and not coil springs. Bushings won't change that. The adjustable Koni's may work but you have to know what strut housings you have, Koni's may not fit. Adjustment will be slight and only really adjusts damping. The torsion bars are the 'spring'.

As for other suspension parts to check or replace, you want to look at the rubber front strut bearing at the top of the tower. If you're doing shocks, swap in new bearings. The sway bar bushings should be swapped out and is a DIY. Rears are easy but the fronts can be tricky.

If you have records on the car, you may learn that bigger torsion bars were put in and that could be why it's stiff. If they're stock, then downsizing to smaller diameter isn't a good suggestion. You may have to live with it or look at tire options to soften the ride a bit. If you intent to do a full a-arm and rear spring plate bushing refresh, look at Elephant Racing parts sold via Pelican. Good factory replacement rubber or their polybronze aftermarket. The polybronze will tighten things up however. Otherwise, just enjoy the car.

Thanks for the advice. I understand that it is supposed to ride stiffer than a normal car and I've had cars with very stiff suspensions before. Not trying to turn a sports car into a GT here or anything, my only concern was that if the level of stiffness was harsher than it was supposed to be and the damage that could cause. I guess the other problem may be that it's the first car with a stiff suspension that I've had since moving to Houston, where the roads are not the greatest.

The main thing was to check and see if there were any common issues that this would have been the symptom for that I had not seen. As long as I'm not beating a 30 year old car harder than it's designed for I'm ok with the ride.

darrin · 02-25-2016, 11:05 AM

speaking of tires, how old are the tires on your 911? Tires get harder/stiffer as they age and older-than-acceptable tires can contribute to the ride issue you're working to resolve.

kevinb34322 · 02-25-2016, 12:13 PM

Good info from all and I appreciate it.

I expect the ride to be stiff and I've had sports cars with a stiff ride before and I'm not trying to turn this thing into grand tourer. It's possible that since I recently moved to Houston and haven't driven a sports car here yet that I'm just now realizing how bad the roads are.

My only concern was that if there was a semi common problem that this would be a symptom for as I don't want to a beat a 30 year old car any harder than it is designed for and spend the rest of my life chasing rattles.

Thanks again!

sugarwood · sugarwood's Garage

Quote:

Originally Posted by SoCalSK8r

Haha, I had the opposite problem. My 84 with 50k miles felt too mushy and unpredictable. A complete refresh with some upgrades made a world of difference, beautiful car btw!

Actually, that doesn't make sense.
When rubber gets dry, it gets brittle and hard.
This would make a harsher ride.
The entire point of rubber is to dampen.
When you replace rubber, the ride should get softer.
Anything else sounds like placebo effect to me.

kevinb34322 · 02-25-2016, 02:26 PM

Quote:

Originally Posted by sugarwood

Actually, that doesn't make sense.
When rubber gets dry, it gets brittle and hard.
This would make a harsher ride.
The entire point of rubber is to dampen.
When you replace rubber, the ride should get softer.
Anything else sounds like placebo effect to me.

This is what I was thinking as to why mine rides a little stiffer than I'd expect. Probably keeping the rubber replacements on the list just based on the visual inspection.

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darrin · 02-25-2016, 02:50 PM

interesting observations -- I always understood that as bushings become worn/aged, they deformed and, along with becoming hard and brittle, also allowed the suspension to develop "slop" -- replacement bushings would both address the harshess caused by the aged/dried bushing's lack of resilience (unless harder replacement bushings like delrin were substituted) and cure the slop caused by the worn bushings' deformation.

winders · 02-25-2016, 03:30 PM

Quote:

Originally Posted by sugarwood

Actually, that doesn't make sense.
When rubber gets dry, it gets brittle and hard.
This would make a harsher ride.
The entire point of rubber is to dampen.
When you replace rubber, the ride should get softer.
Anything else sounds like placebo effect to me.

Sure it does. Old deformed rubber isn't hard enough to make a difference. The difference is that there is now so much more play in the suspension it feels like there is a lot of play...which can make it feel mushy.