IcemanG17

Okay my 24 hours of Lemons racer has an open diff....while it works fine, it clearly holds the car back coming out of slower corners...

Ideally an LSD is the best solution, but its hard to justify under a $500 budget race car

I would think a welded diff would help significantly powering out of corners, but I am worried about the effect it would have on handling...wouldn't it cause MORE mid corner understeer?

I'm also worried about the harshness it would cause the rest of the driveline...especially in U turns etc....

Of course running an automatic helps damp the driveline quite a bit vs a manual...but still I think its risky...

Thoughts-opinons?

Racerrob

I have driven 944's with welded diffs, they understeer like a ****. I think it is faster to "drive around" the open diff issues.

Sterling Doc

Agree, especially on low speed corners. Keep the rear antiswaybar soft , and drive around the open diff.

IcemanG17

I found a great article at Tayor Race that explained the difference in terms of road race cars...it appears an LSD is ideal, but open diffs are pretty much ideal for handling, just with the downside of putting power down.... Just an excuse to be even more smooth I guess....

I could try disconnecting the rear sway bar to increase its traction...but then it would push even worse..which I don't want

RedlineMan

x100.

kurt M

Unless you have a hard time putting the 500+HP down every time you have the steering wheel straight keep the open dif. What you don't have 500+HP in the chump car? Well then, keep the open dif. A welded dif or spool will make the rear wheels try and keep the car moving is a straight line. When you try and turn the car the rear wheels traction will fight with the front wheels traction. The shorter the radius the bigger the fight.

SundayDriver

What do you have for shocks - are they adjustable? Softening rear rebound will help drop the tire to the pavement and get the power down. If they are only compression adjustable, that will normally also adjust rebound. Playing with swaybar could also have some impact on this challenge.

Benton

Brian, search for Norm Goldrich's videos of his turbo 911 beast. I vividly remember watching those 3-5 years ago and listening to how much throttle steering he had to do in order to make the car turn. I think he had a detroit locker in it. Lots of abrupt throttle releasing in an attempt to pitch the rear end around to help with rotation.

CAM14

I’ve had the exact same debate with my Lemons team and our Open Diff problem. We have opted to keep the open diff . My research strongly indicates that a locked diff will induce heavy understeer at turn-in past apex making trail braking very difficult. This will be more pronounced on tighter tracks. But it would greatly improve accelerating past mid-turn on out. In my mind, the cons out weigh the pros in our case. The team car is a 1971 BMW 1600-02, very low power but handles fairly good. I’ve stiffen up the front significantly and running without a rear bar, soft rear springs and done everything I can to assist weight transfer to the rear without upsetting the rest of the car too much. It is a decent compromise on the tight track where we are doing our lemons event (note, I did not say race, it is really an Art Car parade on steroids, lets just call in an Event). I think your event is at Thunderhill which has a nice flow to the track. I could maybe see a locked diff working there but you will compromise your ability to trail brake. I’m assuming they run the whole Thunderhill track, not familiar with the other configuration. Good luck.

kurt M

my car is 2K pounds with 275 hp at the flywheel and an open dif. Other than T1 at Summit I have little to no issues with getting the power down. With T1 I just ajust a little bit to compensate. Dare I say I can drive it "flat out" on almost all conditions. As was said you can tune most of the problems with an open dif out via susp settings. OTOH you can tune the car even better with a good LSD.

M758

Welded diffs are a compromise as they create understeer and stress the diff more. LSD is the best plan, but welded can work. You need to set-up the car for it. In LeMons car I don't know I would even bother. Chances of breaking something go up with welded and you are proabably better off going openand planning on turning laps. Even if you are slightly slower open it iwll be easier on the car. Since the car is already a POS why put more stress in it for little gain?

mark kibort

Brian.......................

I've driven your (this) car, for lots of race hours as you know. the open diff is just fine, especially with the power you have. I have one of the most open diff like LSDs possible, and its still just fine. you just have to be careful on the power, out of very few turns, like turn 11 at laguna/sears and turn 2 at sears. otherwise, its a completely NON issue, especially at 200 rwhp. as you get larger tires in the rear, the problem will possibly go completely away for you.

as far as welding, i thought that would cause a slight oversteer as I noticed when I went from a open diff to an LSD initially. an open diff, just spun the outside tire wildly if you were not careful, but there was plenty of oversteer fighting grip. that same car with a new LSD, allowed for some oversteer out of corners, as both tires now were spinning. great for better launches off the corners, if you controlled it correctly.

So, dont weld it. its fine at your power levels up to near 275hp, BUT do invest in some larger rims all the way around. Its not a lemons car anymore, so since its a pretty decent track car, especially for the cost , just do the things that are proven to help it, and figure out a way to dump the automatic if you reallly want to race it.

mark kibort

Great points. I think the understeer could be pronounced on turn in in thinking about it, and in trail braking. the "locked" diff, probably wouldnt allow the car to rotate. Ive never driven a "locked" diff, but some very stiff LSDs. It probably wouldnt be a good thing to do and experienment with, as undoing it would be a pain.

IcemanG17

granted my brute HP of 195whp isn't exactly overpowering....running the 225/50-16 street tires make it challenging putting power down in tighter turns..... Switching to the 245/45-16 R comps helped a lot...I would imagine even bigger rear tires would help even more.....

The Taylor Race article brought up some good points about how an LSD adds friction, which of course adds heat....so they recommended running a cooler to offset it..... I would guess for sprint races its not needed...but for enduros its probably a good idea....

JustinL

If you welded the diff, would it be possible to set up the car like a kart? Make it so stiff that it lifts the inside rear while cornering?