K24madness

I bent the first gear input shaft at the drags and want to know if this would be a good time to do a 2wd conversion?

Could those who done the conversion tell me how much weight is saves. Do you have to change the tranny? If so then should I look for one with tighter gears ratios. I don't mind giving up top end speed for better performance.

Where else can I save weight?

Jean

K24
The gearbox work is independent from the conversion. You do not need to change anything in your gearbox. Weight savings are around 45-50Kg if I recall correctly, about 100+ lbs.

If you want a good (and expensive) change in your gearbox for cars like yours, put in a Guard billet shaft which comes separate from the 1st gear (unlike OEM) and buy a taller 1st and 2nd gears (3.15:1 and 2.00:1), shorter 3rd and 4th. You are talking substantial money here $3-5k or so. If you go 2WD it is better if you buy a Guard LSD as well. ($2k or so)

Lightweight wheels, GT3 seats, smaller battery, 2WD, CF doors and sunroof delete are big savers. Others are rear seat delete, CF hood, CF fenders. Forget removing padding for a street car. DIET.

p.s. if you tell me what is your trap speed at the drags, I will tell you how to knock off 0.5 to 1 sec.

Jean

I am assuming you don't have the heavy OEM mufflers and you got your LWF. If you do not need A/C remove it, if you go 2WD you can also remove the power steering and make some additional HP and reduce weight.

K24madness

Jean,

Thanks for the weight tips. I am going to replace the battery with a smaller one. Remove the AC compressor and cap the lines. LWF is going in when I drop the trans for the repairs. I will look into the seats but will most likely stop there. Sunroof delete and CF body parts are a little further than I would like to go.

I already have the gaurds LSD. I spoke to Paul yesterday about the new main input shaft. Yes I am going to do the 3.05 first gear. He said it has been quite popular. I am supprised that the 2wd conversion did not save more weight. What does you car weight in at now?

I only made 2 passes down the strip. Both of them were so bad I can't use the information.

First run I dropped the clutch at 2,500 and nearly stalled it in first gear. When I power shifted into second I spun the tires really bad. I was running 45lbs in the rear and 38 in the front.

Second run I set air pressure at 30 lbs and launched it at 5,000 rpms. The car smoked the clutch in first and second before I let off. I was supprised since this is the sachs 800lb GT2 version.

Needless to say my drag days are done with this car. Guess that is way I was the only Porsche out there. This tranny repair won't be cheap. Guess its true the 96 cars have a weak main shaft. The gaurd one will do the trick just fine.

viperbob

K24,

Hope you got my PM response. I can give you more info on the 2wd conversion. I sure liked it and Jean seems to also.

Couple of things on the clutch. Was this the current verion GT2 or a year+ ago model. They make a new one every so often and call it a GT2 model. Second, what type of clutch disc ar you running. Clamping force is one thing, but the proper disc material is also a MAJOR part of the clutch package. High clamping force with a plain organic disc can still cause slippage.

K24madness

Bob,

Yes I did get your PM. Thanks for the info.

I did use the organic disk when I did the clutch upgrade. I like the way it engages. I used the sachs 800lb PP (new style) with it. I think that the slippage was an extream example of abuse. I don't plan to try that again. I will however do the LWF this time around.

Do you recall the weight savings of the 2wd conversion?

ca993twin

K24,

One other "advantage" of going to 2wd is that you'll have less grip which should allow more tire slip and less strain on the drive train. Obviously this has a disadvantage for great 60' times. I hear that while the 1997 shaft is a wee bit stronger, but neither is up to serious drag racing abuse.

Have you been getting out to DE events? Tough on brakes and tires (and potential serious body work if you're not careful), but no real strain on the drive train.

K24madness

CA993twin,

Not really into the track thing. I spend a lot of time behind the wheel in my life as it is. I just want to make my travels from point a-b as enjoyable as possible.

The drag strip was a wild hair thing. It would take some pratice to get good at it. Having a helmet on and not being able to situp straight does not help.

I would love to make my car weight 2,500 lbs. It does not seem possible unless things get pretty excessive. I thought the 2wd conversion would save at least 200lbs. If that were true I would do it in a heartbeat.

I am going with the gaurd input shaft an new 3.05 first gear ratio. This shaft should be damn near bullit proof.

Thinking about dropping the motor at the same time to do cams and some other things. I will keep you guys posted.

Jean

Bob is your man for the 2WD conversion, but the weight he saved will be the same as mine ..50Kgs is also the number quoted by Paul Frere BTW, I just checked.
If you want 2500lbs, your car will not be streetable.
I am confused because, you are saying that the sunroof delete and CF bodywork is beyond where you want to go, yet you want to get to 2500lbs. I have all the above major items done (except the small battery and I have heavyish wheels) and Lexan, and my car weighed 1400Kgs (3000lb +) with the roll cage.
You need another platform.

911/Q45

For drag racing, a 67 Dodge Dart with a 440 should be just right for you.

K24madness

Jean,

I guess what I mean to say is that idealy I would like the car to weight 2,500 lbs. I will live with what it weights based on the sacrifices I am willing to make.

PorschePhD

The conversion is easy. Pull the viscous coupling out of the tranny and the shaft. Put a different nose cover on it and put DME stub axels in the front. That’s it. The conversion is actually very simple. The expense comes from the parts. The job (if your input shaft was not bent) can be done in the car. You can pull the nose off while the engine and tranny stay in place.

Jean

K24, I think it is a great modification even if it does not save you more than 50Kgs or so, and as Stephen said, it is fairly simple, so I would give it more consideration.

Other than the upgraded LSD you need to buy a few C2 and RS parts that will put you at $1k or so (I did not buy a gearbox nose cover, but you can buy it used) if I remember correctly. You can shave around 300lbs from your car and keep it very liveable, you will feel the difference while driving it.

viperbob

The conversion does save just over 100 lbs. If you want to remove the VC, then you will save another 8 lbs or so, but then if you ever want to go back, it is a little more difficult. I think Stephen that K24 is looking to take all of the AWD components out to save weight. While it is easy, there is still some work to do in getting the parts out, and installing a new shifter box properly as you remove the one you have with the torque tube. There are also a number of components now required (front shift rod, front shift rod plate, the ABS wheels for the front with the bolts and new nuts, etc, etc..). Some of the parts have gone up in price Jean since you received yours. The rear RS shift rod that was about $250 is now almost $500.

ruffy

great thread!
just a quick question for the track junkies
ultimately, will i gain or lose time on the track?

I realize the inherent benefits of steer feel. but, I can't see how that could possibly be more effecient/faster than punching out at full power with a 4wd
in theory, mechanical drag at topspeed is the only motivation to remove the 2wd.. correct?
i know of no local tracks where a 993tt can attain absolute topspeed, so that kinda makes mechanical drag redundant.

Please correct me if i am incorrect.
i need to know