RS/Evo Uprights, Tie Rods and Bushing replacement with Updates
#62
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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.
#63
Rennlist Member
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Re: anti-squat effect. I'm not a chassis engineer but read a book or two on the topic... Lowering the front of the subframe must reduce the % anti-squat. This is due to the effect on instant center locations. I assume someone mentioned anti's a long time ago & folks assumed it meant an increase.
A base 993 has 90%+ a/s, really high vs accepted norms (again, not a pro but read online & print). I suspect the effect was reduced in the evo to improve feel & traction at super low ride height & stiff setups.
A base 993 has 90%+ a/s, really high vs accepted norms (again, not a pro but read online & print). I suspect the effect was reduced in the evo to improve feel & traction at super low ride height & stiff setups.
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.
#64
Rennlist Member
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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...
#65
Race Car
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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...
#66
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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
#67
RL Technical Advisor
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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.
If one experiences increased knock sensor activity, I'd be looking for engine-related issues.
#68
King of Cool
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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?
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?
#69
Race Car
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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.
If one experiences increased knock sensor activity, I'd be looking for engine-related issues.
#70
#72
Rennlist Member
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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
#73
King of Cool
Rennlist Member
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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
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
I just ordered one (and while at it, a paint gun), no coupon but still cheap.
#74
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Re: anti-squat effect. I'm not a chassis engineer but read a book or two on the topic... Lowering the front of the subframe must reduce the % anti-squat. This is due to the effect on instant center locations. I assume someone mentioned anti's a long time ago & folks assumed it meant an increase.
A base 993 has 90%+ a/s, really high vs accepted norms (again, not a pro but read online & print). I suspect the effect was reduced in the evo to improve feel & traction at super low ride height & stiff setups.
A base 993 has 90%+ a/s, really high vs accepted norms (again, not a pro but read online & print). I suspect the effect was reduced in the evo to improve feel & traction at super low ride height & stiff setups.
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
![](https://forums.pelicanparts.com/uploads22/7_26_12__+001_annotated1361472058.jpg)
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
#75
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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
a tilt kit that lowers the front of the rear suspension assembly lowers the SVIC and thus lowers AS
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'...
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