jackal2513

An air chisel, like i said over on 911uk

If you don't have one then use a hammer and a regular chisel but you will there a LONG LONG time !

NP993

X2

I did the Rennline solid subframe mounts and posted pics of the procedure. Feel free to search. Getting the bushings out of the suspension frame is a real PITA.

Cupcar

I believe this is correct. The virtual axis of the control arms meets the CG in a way that would decrease anti squat as the frame is tilted. Ant-squat is 93% in a 993 chassis, most cars have around 80% (If the axis meets at ground level anti-squat = 0% if it meets at CG level it is 100%). Anti squat increases as the car is lowered.

Too much anti squat basically "locks up" vertical suspension movement on acceleration decreasing compliance and making the car have a harder time obtaining traction. This effect is greater the greater the acceleration i.e more horsepower = more of an issue.

Cupcar

I have wondered about this since the frequency domain of knocking is unique to an engine and engine to car depending on the mounting. This could be an issue since more "noise" is being passed into the chassis and engine making it harder for the CPU to sort out knock frequency. Same thought with solid engine mounts. Hmm...

trophy

Many of the race cars just don't use the knock sensors for this very reason. I have an engine wiring loom from an 993 RSR at home and there is no provision for Knock sensors. I am not sure this is the same for all RSR's or CUP's, maybe someone has this information.

Bill Verburg

Knock sensors are listed as both Cup and RSR parts

I have solid engine mounts and solid side mounts, to my knowledge there has not been any knock sensor interference, I run only 93 this is w/ RS cams ans RSR p/c which have slightly higher cr than others

Steve Weiner-Rennsport Systems

I'd concur with Bill's observations; I've not noted any increased knock counts (using the Hammer or PST2) with solid subframe mounts. I believe that the Motronic system adequately filters such vibrations from the chassis.

If one experiences increased knock sensor activity, I'd be looking for engine-related issues.

Flying Finn

Hey David,

Somehow missed this so sorry for the late reply.

Mine are all ERP links for rear and busing for the front plus Rennline solid mounts.

I haven't done anything yet (somehow summer was busier than I thought) and should really order the rubber hats for the links but the size for those rubber hats is still a bit of mystery to me although I have to admit, I haven't really looked into it much...

Freddy, did you get the rubber hats? If yes, from where?

trophy

When the RSR's ran with other than Bosch ECU (Zytec etc) did they just do away with the knock sensors?

Bill Verburg

W/ Tag 3.8 engine control they did, I have no info on Zytec

trophy

Thanks Bill....

Back to the regularly scheduled programming....

Cupcar

The tool below removes them in seconds. I was pretty amazed actually.

Not pictured in the link are the actual chisels that go in the tool. AT $14.99, never a dollar better spent by me (Don't forget to take along a Harbor Freight 20% off coupons to make it $3 cheaper!!).

http://www.harborfreight.com/super-d...els-47868.html

Flying Finn

Thanks for the link!
I just ordered one (and while at it, a paint gun), no coupon but still cheap.

Bill Verburg

I agree
The side view instant center shown here is quite high, as Cupcar says the antiquat for a 993 stock is quite high @ 93% w/ an also high antidive of 73% 996/997 have lower #s for both @ 67% AS and 64% AD though the roll centers are all pretty much the same


a tilt kit that lowers the front of the rear suspension assembly lowers the SVIC and thus lowers AS

It makes sense to do that on a high powered car as it help to put power down at the expense of power on steering, this could explain why it's such a Bitc* to reduce 993 under steer coming off a corner.

The big mystery is why these tilt kits are said to stiffen the rear axle, when to my mind they do the oposite

ToSi

Longer wheelbase on the newer cars means less anti required to maintain the same amount of total chassis pitch.

Incidentally, while the rear has lots of anti-dive, the front is actually pro-dive (12%). I suspect this is a significant reason for running higher front vs. rear spring ratios on race cars, despite the wonky effects on ride frequencies. It might make more sense to tilt the front 'subframe'...

{gasp} incorrect information on the internet?? I suspect (hope) whoever started marketing these long ago meant stiffening the fore-aft compliance by removing the rubber bushings.