Lefty's Deceiver

I have a 93 RSA which I'm thinking about racing in PCA and NASA. Unfortunately it has a sunroof but more importantly it does not have a LSD.

Now I put a LSD in my 74 and it helped on a specific track (Grattan's hairpin 2nd gear turn 8). I'm not racing at Grattan but I'm wondering how much of a handicap not having a LSD will be at Road America, Gingerman, Blackhawk, Putnam.

I'm tempted not to race the RSA because this just adds to an already long list of things I've got to do to the car and is VERY expensive (I'm thinking $2k). Maybe I should prep the 74?

Thanks
Lefty

Geo

Well, I just gambled $1,600 for a Guard GT 80% lock-up diff (arrived today! ) because I think it will help a LOT. Pretty good bet I'd wager (oh, betting on a bet ). Despite those who don't have one who don't feel they need one, from everything I've read, if you want to build a serious race car, a LSD is a must. They should make getting out of corners (some more than others) MUCH easier and sooner.

kary993

I have a Guard in my 993 I find it simply awesome. Getting out of corners, particuarly off camber corners works very well and the lock up of the differential while under heavy braking is also a real plus. It is clearly worth a few seconds on some courses while others just a second or so. I would do it because I did and I think it is worth it.

Honkity Hank

After LSD my whole outlook on life changed, colors were more vivid, and ..... oh sorry wrong LSD. I certainly hope it makes a difference as I am having one put in my 951 as we speak. At Road Atlanta it will make getting power down out of 7, 10b and the bump under the bridge in 11 better, I will be able to report better afer this weekend though.

Mike Buck

Looking back, the LSD should have been my first mod, not the last.

This year I'll get to try it a full spectrum of courses. The one event I did late last year with it at Summit Point was eye opening. Come around T5, drop to 2nd and just mash the throttle. Didn't matter if the car was straight, it just hooked up and rocketed towards T6. Same line with the open-dif = instant tire (1) smoke.

Lefty's Deceiver

Thanks for those who took the time to respond. I guess I could have answered my own question. I put a monster 80% lockup in my 74 and it just pulls out of any corner without spinning any wheels unlike previously.

Thanks
Lefty

JackOlsen

I'll take the opposing view. I've driven with and without it. In my experience, it's an important fine-tuning tool in getting fractions of a second faster, but it's not going to transform your driving experience. Especially when you're starting out with a new car, it's not going to make a huge difference.

(That said, I wouldn't willingly give mine up. )

eimc

I have driven LSD , locked ,80/20's etc . Locked you have to learn to handle it and not to make any sparp turns in pits,also hard to push in paddock. Lsd woprks great on road courses as does 80/20. But 80/20 has a better advantage on autocross courses. I would not even think of competing without LSD,once you drive with it you will see the definate advantage.

DrJupeman

To get the most out of a LSD you need to know how to drive with one. Most of the folks here are giving the positives of traction exiting a turn. There isn't too much to maximizing this benefit. Step on the gas!

To really improve your laptimes you want a LSD that will lock or approach lock on deceleration. This will induce a ton of understeer. Why is that good? Because it counteracts the oversteer you introduce by trail braking. Thus, if you're good, you can enter the beginning of a turn fairly neutral but trail braking. This should help your laptimes.

Porsche started getting clever with this and offered split ratio LSDs in the early 90's (all C2 Turbos have them). My LSD is only 20% on acceleration (works great with my 380 rwft/lbs turbo and helps keep the understeer under control when accelerating) but 100% on deceleration. She becomes a locker when you start to slow down. If you don't know how to handle this you will experience massive understeer. But if you understand what is going on you can fiercely trail brake. And survive.

Obviously the side benefit of the 100% lock, particularly in the beastly last single turbos, is that it helps control trailng throttle oversteer.

James Achard

Dr. Juperman hit the nail on the head. Acceleration is great but the stability in trail braking is really where a LSD helps in laptimes. My suggestion would be to speak with Paul Guard directly and he can match an LSD to the Hp. output of your car. He built up a custom one for my car and it's fantastic. The control I have during trail braking really built up my confidence.

Cheers, James

Lefty's Deceiver

Charlie,

That explains what I'm experiencing with my 74: It doesn't like to oversteer when trailing the brakes deep into the corner. Of course it will go around if you abuse it but a touch of opposite steering and some gas pulls it straight.

Thanks for the insight.

Lefty

Bill L Seifert

Geo, $1,600, holy cow! Do you have the .83 5th gear, as opposed to the .73 in the 84 rear end? By the way did you get my PM about the A arm? I have it but lost the ball joint. PM me, please.

To Lefty, I'm a little late responding, but limited slip is invaluable. It knocked off almost 1/4 second at Gingerman for me, have'nt been to the other tracks.

Bill Seifert

1987 944S Race Car

Geo

I doubt I have the lower ratio. Yet. I still have to finish the car. Nine months of unemployment last year threw a wet blanket on that. But, I'm getting kick started again now that things are back to normal. I've got some wheels to sell (out of my 50+ collection for various cars) and when I do that I'm going to order my dampers. That will be the last major thing until I get a spare engine to build properly. I'll probably do the 5th gear ratio around that time.

I got it. If I didn't respond, I apologize. I sure meant to. Things have been a bit crazy with getting the job and training for the Houston and Little Rock marathons.

Geo

Bill, your mailbox is full.

Bill L Seifert

Geo,

Thanks, I'll clean it out.

Bill