Porsche have been notorious for pushing, I found out from some of the race groups at this weekends event that even the cup cars are a handful when it some to this. So my question to all the RWD guys is how do you manage the push that plague us all. More weight = More push/ less weight at front of car = more push.

My fastest lap this weekend was on a full tank of gas, because I had weight in the front of the car/ on top of the front diff weight. When I did the IMPROPER conversion, the car still pushed (even with drag ). I cant imagine taking 70 more lbs out of the front of the car, that's crazy.

Not to mention the weight bias gets 70 lbs worse in favor of the rear. So what's the solution? Or are all the RWD guys too busy drag racing to consider handling??? Has anyone in a RWD turbo (not GT2) actually road coursed their turbo????

If your going to argue about front wheels turning etc, I call b.s. because my front wheels couldnt even turn dyno rollers with max load on them so there isnt enough power going to them to cause torrential understeer alone, that can not be fully attributed to AWD.

 

I would like to know a solution as well..but heres my 2 cents.

About two weeks ago i went to thunderhill, i took out the front spare tire off the car. I felt like the front of the car was going to go flying off. I had one the members from this board ride with me, and he was surprised how much i kept correcting the steering wheel because the front would just wash off.

I was pretty bumped out because at first i didnt think it was the weight issue.

I was running 34 psi in the front hot and 38 psi in the rear hot. So i kept playing with the psi and i came to the conclusion that was the best setup... istarted at 38psi in the front and 44 in the rear and worked my way down.

But still it was not optimal --the car just didnt feel 'right' i got so mad and blamed it on the ps2 tires i had in the front. After sitting down and cooling off. I thought tomyself-- that at laguna it was pushing but not as much as it was at thunderhill...only two things were different.

1) front tires were bridgestones
2) i had the front spare tire

So everyone says the ps2's are better then the bridgestones so i rode that one off...

My only conclusion is the front spare tire. So i have a little project i want to work on. And that is to remove as much weight i can from the back of the car...and move the passanger seat forward as much as i can when i go to the track... also take bags(sand/rice/beans -- not sure yet) of 10-15-20-50 lbs and play with weight distribution next time i'm at the track..by putting it in the front area compartment....

Removing weight in the front is a big no no imo...it has to come from the rear of the car...


I don't know how to setup a car which is my weak link but i think... if i had an adjustable suspension.. i would have the car ride lower in the front then in the rear... have siffer front end and softer rear end...more camber in the front then in the rear....and i think that would cure alot of understeer....any pro teams like GMG care to contribute ?


Also another thing i want to contribute ...perhaps its just me...but i have changed my style of drving/entering a corner/breaking due to this awd system/weight distribution...causing this push..has anyone changed their driving style due to this as well ?

 

Wow, lot of issues here. I think if the car has a proper track suspension and is corner balanced that addresses most of the above. I would limit my comments to R compound tires as street tires add too much variablity.
I thought the RWD idea for the track was to be able to induce oversteer and have more throttle steer as opposed to the AWD.
Still the majority of handling characteristics in this car comes from its weight and rear engine. This mandates two things for me, later apexing and trail braking.
Would love some input from drivers better than I.....Sechsgang??
Also, all of us getting to a track together would be awesome!!! For as you can see we have a particular set of issues that do deal with just our cars.

 

Steps of getting rid of push (I am saying this because I dont know how much you have done yet).

#1 Stiff Rear Sway, on max stiff. (help reduce understeer considerably.
#2 Sticker Tires (help a lot with turn in)
#3 Aggressive front camber adjustment (mine is about 2.5 front, cup cars run 4.5 front)
#4 Some form of front downforce, dont know what we have available for the TT.

This will get rid of the push for 90% (unfortunately I'm not in that group) of people's driving skills, off camber turns and decreasing radius turns will still bother you though.


Check out this from Wikpedia, its a good read.
http://en.wikipedia.org/wiki/Understeer


And one more thing, I would think that not only removing weight, but the addition of a roll cage would make the bias even worse then. That has got to be terrible! What about removing the Rear diff and making the car rear engine front wheel drive.????

 

That is funny.

 

Stiffer rear sway bar?

 

What exactly entails proper track suspension? Coilovers and what else?

Late apexing works but only when you dont have an increasingly off camber (meaning closer you get to turn in, more off camber) turn, you have to go in VERY slow.

Trail braking does help. I guess my problem is that RA has two turns that make late apexing and Trail braking of no effect. Turn 7 is WAY off camber, late apexing here puts you more off camber. Trail braking does help some here though. Turn 10b, you cant trail brake here because you used all your braking for 10a, late apexing is not effective either because you need the momentum to get up the huge hill you face.

 

This helps A LOT, but it helps to reduce the push by a huge margin. There is an aspect of getting the rear end around a turn that it does not help with though. There are still lots of adjustments neccessary to make this car a real handler. On a tigh twistie course, you'd get owned.

 

i agree

hmm my car is pretty much stock...no suspension work yet..
I'm waiting for my warranty to be over so i can start moding it more...

hmm so you think removing weight from the back of the car would make it worse?

I was thinking of removing the rear bumber plate thing that weights between 30-60 lbs.. some weight is better then nothing.

At the moment, i have i can say i have no confidence in this car at high speed turns...for example turn 7 i believe at thunderhill i was approaching more then 120mph and the car just washed out on me..i nearly lost it if it wasent for some quick reflex...and the thing is.. its not even a tight turn.. just a slight left...then again my tires appeared to be very greesy... hmm i had no grip that day thats all i can recall...also i think the suspension is way to soft.. i have a few pictures when i was at laguna and thunderhill..at laguna i kept getting the front off the ground, at thunderhill i felt it wanthing to lift off and some pictures i have confirm that...the weak link is the front end...someone find a solution and pass it on

 

No no, I was saying that the removal of weight from the front and adding weight to the rear(roll bar), would make the bias even worse. If you go the the weight loss thread you'll see that you can remove lots of weight and a majority of it comes from the front of the car.

Places with unmatched weight loss opportunity from the rear.

Brakes (majority front) (26lbs)
RWD Conversion (Front) (71 lbs)
Battery (Front) (15-30 lbs)
Spare Tire Removal (Front) (39.3 lbs)

150 lbs gone from the front of the car, the worst place you can lose it.

 

I changed only the rear sway bar and this helped my turn in and crispness of the steering immediately. I am still AWD though.

Good Luck Heavy, you have lots of great track experience and good thoughful questions.

MK

 

Great thread!

I was at an autocross yesterday and have done an improper RWD conversion just to see how the car feels. For the record, I also have Eibach adjustable sways set on med/med to start with and a Tequipment bar (no cross brace but a custom harness/cross bar installed) I removed the drive shaft and axles but still have the diff in the car for now. I initially removed the spare tire and went out and was pushing the front all over the place! I played with tire pressures and wound up settling at about 34 front, 38 rear as well.

Mid day, I put back in my spare tire and it seemed to help a bit, but I also just started using the throttle to steer the car a bit more and cleaned up my lines in a few places.

I think that my next step is to tighten up the rear sway and see how it feels. I may then remove the front diff. and 'finish' (whatever that means?) the RWD conversion by taking the car to get corner balanced and set up by a pro... Any other suggestions for me?

The main mod that I'm trying to make right now is the "Driver Mod" by taking some more driver training!!!

 

Heavy,

Let me make something very clear to you; anyone on this forum can reply to any thread you post on this forum. You are not in a position to tell people otherwise. Do you understand? I hope so. I hope this is crystal clear.

I realize that you've suffered some embarrassment recently here on the forum, but you really need to get rid of the attitude.

 

LOL....heavy continues to show creativity in his crusade to put an end to the evil plaque of RWD on the Porsche community. I give you credit for your consistency and determination.

Oh, Scott, the answer to your question is 45.

 

Not true at all. It really doesn't matter where the weight comes from. That's what corner-balancing is for.