Cupcar

I made them to eliminate the rubber which I think not only eliminates potential steering motions of the rear suspension but also triangulates the floor of the car up to the frame rails along side the engine more stiffly.

The bolts thread into internally threaded steel cylinders that are welded into the chassis and mine were not perfectly square to the sub frame. The car has not been crashed and I think Porsche didn't feel that 100% square was a necessary quality factor since the rubber in the original mounts would take care of this.

I took a photo to show the movement at the washers as shown at the arrows (sorry on the focus). It is not much and this picture is of the worst case present on my car. All mounts have a bit.



Spherical washers are commercially available, I got mine from Morton Machine - a nice place to shop for other stuff as well BTW http://www.mortonmachine.com/index.p...l-washer-sets/

The other parts were made for me by a friend with a CNC shop. They are pretty simple plugs that press fit into the subframe.

Cupcar

I forgot - the reason for the 10 mm elevation is to lower the car by that amount without loss of suspension motion and roll center changes. This is what I believe Porsche did in the 993 race cars and I know they do in GT3 cars (as well as eliminate the rubber in the GT3).

jstyer

Any chance you still have the CAD files for the insert pieces? Even a dime signed hand drawing would work, so I could model up the same thing.

IXLR8

Thanks for the explanations, Cupcar. BTW, still have your old PM re other suspension explanations.

Also bookmarked Morton's...added to my Fastener folder.

Cupcar

Sadly, I threw away my initial hand drawn design sketches and don't have the CAD files.

I will see what I can do with providing a sketch with dimensions, but it will take a bit of time.

Knight

Gents just bumping the thread as I'm in the process of refreshing my rear suspension, as usual unexpected but of course while you there might as well do it right.

I replacing all the rear arms, very likely going with RS A arms and KT arms, as Bill noted in many other posts these haver stiffer bushings. Doing also OEM camber arm + Tarret rear toe link arm.

I did notice the price difference of say the Tarrett solids vs Elephant racing rubber is only ~ $50. Assuming might as well just go solids.

http://www.tarett.com/items/993-964-...-xx-detail.htm

http://www.elephantracing.com/suspen...erbushings.htm

How much labor is involved in the changing subframe mounts? Keep in mind I'll be doing the the rear arms as noted above, I do have a 993TT, so AWD.

Martin S.

Just go to Tarrett Engineering and get all the ERP links and mono-*****. This is what I did and have no regrets...rugged material. Cupcar managed to get his hands on OEM 993 RS stuff as I recalled and made his own sub-frame mounts.

Bill Verburg

The kit Tarett sells looks to be made by Rennline, check Rennline's pricing, Rennline used to sell the bolts separately, you will want them so check into that too. A friend of mine installed the very first Rennline kit on his car, thanks to his feedback they changed them to be a perfect fit.

The Elephant ones are rubber like the oes, you can choose stock or sport hardness, if you want to copy the RS suspension exactly use the Sport hardness versions, for track use and if the car is at the low end of RS or into Cup territory then use the solid flat ones Though w/ a turbo it may be worth while to go w/ the tilt kit.

I didn't find them to be difficult to install if you have a lift and air tools, the old ones popped right out of mine w/ an air chisel, the caveat here is that the whole suspension was apart, all the arms were off both sides. So my advice is do it when the arms are going to be replaced. The factory ball joint tool or it's like should be available if you want to reuse the arms, a pickle fork is likely to damage the ball joints if you use one.

In front the RS only used the stiffer rubber on the trailing leg of the track arm, rather than buy RS parts a cheaper solution is to use the Elephant Sport rubber bushes(I used them on both leading and trailing legs and liked them so much that when I changed to all mono-***** I saved the assemblies for the day I stop tracking the car)

As You are planning in back, the RS track arm and RS KT arm are excellent choices, w/ oe camber and Tarrett toe(w/ locks and boots)last I heard the RS KT arm was on indefinite back order, if it still is then you can use an Elephant sport rubber bearing those 2 arms too.

Knight

Martin/Bill....thanks for the feedback.

ERP, jesus very tempting!

What started all this is I really needed a lower control A-arm + toe arm + bushings, my rear suspension is getting movement so it's really tough to isolate is this one spot or a variety of areas, I'm very sure the socket is done on the lower control A-arm too.

So even if I got ERP, I still need a new lower control A-arm to install them.

It's gets to be a very confusing slope, cause you don't want to just possibly fix 1/2 the problem. The local shop did also mention keeping the upper camber and KT arm but installing monoballs or firmer bushings into them. Again some of these options only come in full kits so it gets more complicated or worse case I replace the bushings to find out I need new sockets too.

And of course the big ?, is this going too far for a primary street with say 2-3 DEs at max/year. So comfort on regular street use is a priority too.

Bill Verburg

For an all out track a full mono-ball suspension is the way to go, for occasional track use as you describe the RS /sport rubber setup is the way to go

If going all mono-ball,
: elephant sealed mono-***** for the track arm, RS wheel carriers, RS/RSR tierods, properly valved competition shocks, RS or RSR sways w/ RS or RSR bushes, some nice stiff springs


Rear:
RSR track arm(bigger bearing than other choices), Rennline camber/KT/Toe arms w/ locks and boots, RS or RSR sways w/ RS or RSR bushes, some nice stiff springs

Cupcar

IMHO, a nice set up would be the component philosophy Porsche used on GT3 RS 4.0.

For 993 this would mean monoball track and toe arms, RS rubber upper links and solid subframe mounts.

This way the heaviest loaded parts are metal to metal and the less loaded parts are of noise isolating rubber. This also eliminates the 993's passive 4 wheel steering.

TheBen

Is there a benefit for regular street use?

Knight

Correct these don't seem to be available anymore, if anyone knows where to source please let me know as I'd prefer not use my existing arms as my sockets I think need to be changed too.

Bill Verburg

There is a range of setups that vary in precision response and comfort
most precise, responsive and uncomfortable will be full steel mono-*****, there is no give no play, the car reacts immediately to driver and road inputs

least precise, responsive and most comfortable is the stock soft rubber bush setup it's a sportscar so still handles decently just way back from what the full mono-ball setup does

in between there is the mostly sport rubber RS setup and various other combinations of rubber, sport rubber and steel.

What bet for any individual depends on how they use the car and what they expect from it

RS has mono-ball shock top mounts and stiffer sport rubber on the trailing leg of the front track arm, on the trailing leg of the rear track arm and on the KT arm and on the sway bar bushes and on the steering tierod, but the same softer rubber everywhere else

The last setup I had was a bit tighter than RS as I had the RS but also used sport rubber on both legs of the front track arms and mono-ball rear toe arms and mono-ball steering arms, This is a very nice dual use setup biased for track use due to the toe arms, if biased to street use I'd use regular toe arms

Each piece of rubber that you stiffen or replace w/ steel eliminates response delays and adds precision but also adds harshness you'll have to find your own 'ideal' setup

Jwolf427

I just ordered the kit and was wondering if the install can be done with the car on floor jacks.