Rake that Understeer good bye!
02-18-2003, 01:24 PM
#1
Burning Brakes
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Rake that Understeer good bye!
Does anyone out there have any experience in adjusting the rake, such that, it balances the 993tt classic awd push?...
it was a suggestion made by a friend of mine who races in formula... problem is, not knowing if that translates the same for the porsche as it would in a single seater tub
Or should i go jack some luck sod who owns a GT2
heh heh if i catch him
it was a suggestion made by a friend of mine who races in formula... problem is, not knowing if that translates the same for the porsche as it would in a single seater tub
Or should i go jack some luck sod who owns a GT2
heh heh if i catch him
02-18-2003, 04:07 PM
#3
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I am sure it will help but you probably have to do a bit more than just the rake to get some of the understeer out. Increase front negative camber, decrease rear camber a bit, and stiffen rear sway bar. These could all be done relatively cheaply.
02-18-2003, 04:20 PM
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Steve,
So in order to achieve this nose down balance, what does this relate to in terms of ride height difference? I know this is a can of worms as I have searched through the archives, but any insight would be great as I am just completing my PSS9 install and take to have corner balanced and set up next week.
Thanks
Bob
So in order to achieve this nose down balance, what does this relate to in terms of ride height difference? I know this is a can of worms as I have searched through the archives, but any insight would be great as I am just completing my PSS9 install and take to have corner balanced and set up next week.
Thanks
Bob
02-19-2003, 12:51 AM
#5
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</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by viperbob:
<strong>Steve,
So in order to achieve this nose down balance, what does this relate to in terms of ride height difference? I know this is a can of worms as I have searched through the archives, but any insight would be great as I am just completing my PSS9 install and take to have corner balanced and set up next week.
Thanks
Bob</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi Bob:
I do not use ride height numbers for setting the rake. I place my digital protractor in the door sills with the car on the alignment rack (its perfectly level) and observe the numbers.
This procedure is done in conjunction with corner-balancing as everything will be changing,.....
<strong>Steve,
So in order to achieve this nose down balance, what does this relate to in terms of ride height difference? I know this is a can of worms as I have searched through the archives, but any insight would be great as I am just completing my PSS9 install and take to have corner balanced and set up next week.
Thanks
Bob</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi Bob:
I do not use ride height numbers for setting the rake. I place my digital protractor in the door sills with the car on the alignment rack (its perfectly level) and observe the numbers.
This procedure is done in conjunction with corner-balancing as everything will be changing,.....
02-21-2003, 01:06 AM
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Burning Brakes
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greg,
i think camber changes might help after the initial turn in to reduce scrub(a slight toe out too, castor also)... i was hoping that by adjusting the rake that the inherent weight balance would be higher at the back and hence be able to flick out a little better without having to provoke it with extremely heavy trail braking... which has subsequently changed my driving style to over trailing... i do have full bracing below and on top already, just need to learn how to dial in the right combo for my style... does any of that actually make sense?
In anycase...i'm probably nit picking.... just hoping to squeeze out just a little bit more... i.e a couple tenths more on after the straights following a tight hairpin could mean alot... if i can get the car a little more sidewards with sharper turn in... yah?...maybe?
too many things to do...
too little time
i think camber changes might help after the initial turn in to reduce scrub(a slight toe out too, castor also)... i was hoping that by adjusting the rake that the inherent weight balance would be higher at the back and hence be able to flick out a little better without having to provoke it with extremely heavy trail braking... which has subsequently changed my driving style to over trailing... i do have full bracing below and on top already, just need to learn how to dial in the right combo for my style... does any of that actually make sense?
In anycase...i'm probably nit picking.... just hoping to squeeze out just a little bit more... i.e a couple tenths more on after the straights following a tight hairpin could mean alot... if i can get the car a little more sidewards with sharper turn in... yah?...maybe?
too many things to do...
too little time
02-21-2003, 11:33 AM
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I would be leery of aligning your car with toe out, front or rear. You will find yourself with a very loose car and/or one that will not track and snap steer into a corner. BTDT. Use a few mm of toe in, front and rear and you will be fine. Yes adjusting the ride height might help, but not to the same degree that you would see in lighter weight formula cars.
A suspension and adjustable bars, along with a good alignment will work wonders IMO.
A suspension and adjustable bars, along with a good alignment will work wonders IMO.
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02-24-2003, 11:24 AM
#8
Burning Brakes
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thanks greg
will try those out... i suppose if i tighten up the rear a little... i might get what i need. only problem is i dont got a track to do it on because those formula one boys have besieged the local track
btw...(thats if your interested to know)
i got my block out and had a look at the heads,
apparantly the play in the valves are too high.
according to the master tech, he says its probably worth 50 to 80 hp... due to loss of turbo compression. not sure if he's telling the truth... but anyways sent it to get revalved= costs a bomb
so i'll probably test your suggestions first before being too agressive on the active setup...
just incase i overdo it
will try those out... i suppose if i tighten up the rear a little... i might get what i need. only problem is i dont got a track to do it on because those formula one boys have besieged the local track
btw...(thats if your interested to know)
i got my block out and had a look at the heads,
apparantly the play in the valves are too high.
according to the master tech, he says its probably worth 50 to 80 hp... due to loss of turbo compression. not sure if he's telling the truth... but anyways sent it to get revalved= costs a bomb
so i'll probably test your suggestions first before being too agressive on the active setup...
just incase i overdo it
02-25-2003, 10:28 AM
#9
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I hate understeer...
You 993 guys are lucky to have adjustable coilovers. My 996 is non-adjustable. I would need a set of aftermarket springs etc. to get rid of understeer if I had a C4....
The C2 has just a bit of understeer as well (although not near the amount of a C4) which I dialed out with adding a wider front rim (same tire size) and manipluating tire pressure, adding as much neg camber in front as I can, etc.
Good Luck!
You 993 guys are lucky to have adjustable coilovers. My 996 is non-adjustable. I would need a set of aftermarket springs etc. to get rid of understeer if I had a C4....
The C2 has just a bit of understeer as well (although not near the amount of a C4) which I dialed out with adding a wider front rim (same tire size) and manipluating tire pressure, adding as much neg camber in front as I can, etc.
Good Luck!
02-27-2003, 11:46 AM
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Burning Brakes
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john
just thought i might add that the porsche generally has different line then most front engine cars. I have a feeling much of it has to do with my driving style...
i sat through a little excercise with my driving instructor... basically he made me turn in unnaturally late to demonstrate how much play the 993 rearend will give. surprising i found myself unaturally sidewards alot... unfortunately, i cant seem to replicate this on my own
probably isn't something new to you but... probably worth trying just for fun, it seems the chassis likes to be balanced at the knife edge where trailing your brakes and entering the corner makes the best overall speed...
just thought i'd share my experience B-)
just thought i might add that the porsche generally has different line then most front engine cars. I have a feeling much of it has to do with my driving style...
i sat through a little excercise with my driving instructor... basically he made me turn in unnaturally late to demonstrate how much play the 993 rearend will give. surprising i found myself unaturally sidewards alot... unfortunately, i cant seem to replicate this on my own
probably isn't something new to you but... probably worth trying just for fun, it seems the chassis likes to be balanced at the knife edge where trailing your brakes and entering the corner makes the best overall speed...
just thought i'd share my experience B-)
