993 TT bad handling around at speed

[rft218]

Hi all,

Having put new calipers and many new brake parts on my 993TT I am now out and about trying to enjoy it and forget about the cost of the calipers

The car handles really well up to about 70ish but beyond that if you are on a motorway particularly if the surface is rough I get what feels like the wheels are out of balance and vibration through the wheel and just doesnt have the stability I woudl like. I tried turning the wheel to see if it is bearings but no noticeable difference.

The wheels have been balanced in the last 200 miles, and prior to that,I have done a lot of work on the car, within the last 15K miles have done steering rack and arms, wishbone bushes (with Superpro bushes), arb bushes. It was aligned a while back by Autofarm but recently after I did the rack by a local guy with the a good 4 wheel alignment machine and he didnt touch the back. The shocks are not new but have probably done 50k miles but are standard.

I dont really know what to do. It just sailed through an MOT by someone who did spend some time trying to find anything loose.

I appreciate the front end is much different to the early cars but someone might have some ideas or any recommendations on people who know 993s well to give me direction!

Cheers

Roger

[Brewster]

When I had a (N/A) 993 on standard Sachs shocks the handling was abysmal. They aren't good for more than 40k miles apparently. I would advise changing those. I went for Bilstein B6 items. It changed the car. I don't know if a turbo is the same, but if it still has the factory items I'd advise refreshing.

[sladey]

Take it to Chris at Center Gravity - http://www.centregravity.co.uk/

Used him a few times as have many others on here. He is not cheap but excellent. He can test your shocks are working OK

[inaglasshouse]

Take it to Chris at Center Gravity - http://www.centregravity.co.uk/

Used him a few times as have many others on here. He is not cheap but excellent. He can test your shocks are working OK

+1
My 993 was set up by Chris.
In my case the original shocks tested OK, but the car was still transformed by replacement of bushes, careful setup, (probably unneccessary) Bilstein PSS10s.

[Brewster]

I've had both my 911 and my Civic Type R set up at CG. They do a terrific job.

[rft218]

cool thanks - I think I will make a trip to him before doing anything else!

[andytat]

The ball joints on the rear toe links on 993s are fairly weak
and have a massive impact on stability and the rear doesn't
get the same treatment as the front when the car is mot'd.
The ball joints on the other rear suspension links do wear
so it might be a good ides to have the rear end checked out.
Hope that helps.

Andy

[rft218]

Hi Andy,

That is an interesting suggestion. I will have a more detailed look at the back, some of the arms I had to change a while back as I could not adjust some of the adjustment bolts. I will have a look at what has been changed.

As a follow on does anyone know if Bilstein b6's are a standard replacement for Turbo suspension. Will it make it harder than standard or about the same?

Thanks

Roger

[shoestring7]

I had a 968CS, it always wandered around a bit at speed and didn't inspire much confidence particularly on poor surfaces. I had the dampers* changed - nothing special just Koni Sports - and it transformed the car. Arrow straight stability, more compliant ride with much better body control. I was surprised at the way it also reduced driver fatigue in longer journeys.

I now treat dampers as a ~40k service item.

>C
*They damp the springs, it's the springs that absorb road shock

[rft218]

Hi all,

Have taken the leap and decided to change the shocks as a start point. New very shiny Bilstein B6s in my porch

Will post results soon!

Cheers

[andytat]

Sorry, I missed your previous post Roger.
I have fitted B6s with good results to 993 Turbos.
It's very important to have a very good alignment carried out
including the rear kinematics otherwise the car will be all over
the place. btw. It's difficult to feel free play in the rear links so
I made a copy of the Porsche special tool which is a flat plate
that bolts to the rear hub using the wheel studs. I welded a
5' long piece of 2" pipe to this so that you can get plenty of
leverage on the rear suspension and check for any movement.
You don't want to overdo it though in case you bend something!
I hope that's useful.

Cheers.

Andy

[rft218]

Hi Andy,

That sounds like an interesting idea. Understand about the alignment.

When the shocks were just changed there was one of the rear wishbones that the rubber was not sitting right so I will change that. I also have an arm that I cant adjust on the back so I need to tackle that which looks more difficult. Some time ago on one of the arms on the other side I had to cut off in small chunks where the bolt had corroded itself to the inner bush of the rubber.

I will also knock up a 'checking tool' to see what I can find!

Thanks

Roger

[rft218]

Hi All,

Bilstein's on and completely transformed it much more settled and controlled, good news. Will do further checks on back arms and then get it aligned again,

Thanks all,

Roger

[rft218]

Hi All,

Got a basic 4 wheel alignment and handling has been completely improved, so Bilsteins and one rear arm later I am in a much happier place

I have one rear tip arm that wont adjust but is currently in range but at some point will tackle this and do a proper corner weighting number. The only thing stopping me is that I will have to remove a turbo piece and all sorts of stuff to get to the nut on the arm before I can even worry about removing it. I have the crank and heads back for my 3.2 rebuild so that needs some attention next!

Cheers

Roger