After reading about a welded diff on a Omni GLH Rally car in Reader's Rides - I was wondering what the benefits or drawbacks there are to welding a diff in a front wheel drive car for Autocrossing and Hillclimbing?
What are the dynamics for cornering? Turn-in? Would it have a whole lot of Understeer? Can it be tuned out with suspension adjustments?
What is the effect on the tranny - will it wear faster? How about the Axles?
Lastly - what are the tire-wear characteristics?
Aack! 
Don't even think about it. Turn in? It won't. Understeer? It will. Wear faster? Yep, and break things too. I can't think of how bad that car would drive. Actually, I can - I drove Lee Graser's 323GTX at one of the early challenge events in the rain and ran over 6 cones with it. All at the same time.
You will probably lose your arms. Even a fwd drag car with a spool is bad enough trying to turn.
It works on dirt because both wheels can slip on the surface unevenly fairly easily.
Ugghh.
I used to race an ITC Fiesta along with Tom Spangler who's also on this board. I had a Viscous LSD from a Euro Escort RS Turbo, Tom had a welded front diff, ask him how he liked it. Other than being impossible to steer it did a great job of destroying halfshafts, hubs etc. One good thing about that diff, it is that thanks to it that Tom and I are friends. At our Drivers school his car ate a hub and tossed a wheel out of the circuit and hit a spectators vehicle! Tom then came looking for spares and we've been friends ever since :)
Ade speaks the truth. Here's how that car handled: It didn't. It was push city on corner entry unless you added some throttle, then it would turn. The guy I bought it from compared it to a jet ski. I'll repeat, unless you were on the throttle, that car simply would not turn, especially near the limit. This led to a very scary moment when I turned in too early at Waterford's Big Bend and was heading for the outside wall with no alternative but to keep my foot buried in it and hope for the best. I let another friend co-drive it, he said that the only vehicle he'd ever driven that handled worse was an early 60s F-100 pickup truck. Oh, yeah, and that car was impossible to push around in the pits, too. In a straight line it would roll along just fine, as soon as you turned the wheel just a little, it would stop on a dime.
Don't.
Run away! See if you can get a Quaiffe for it.
Tom_Spangler wrote: Ade speaks the truth. Here's how that car handled: It didn't. It was push city on corner entry unless you added some throttle, then it would turn. The guy I bought it from compared it to a jet ski. I'll repeat, unless you were on the throttle, that car simply would not turn, especially near the limit. This led to a very scary moment when I turned in too early at Waterford's Big Bend and was heading for the outside wall with no alternative but to keep my foot buried in it and hope for the best. I let another friend co-drive it, he said that the only vehicle he'd ever driven that handled worse was an early 60s F-100 pickup truck. Oh, yeah, and that car was impossible to push around in the pits, too. In a straight line it would roll along just fine, as soon as you turned the wheel just a little, it would stop on a dime. Don't.
HHmm you being more polite than usual on the subject!
you don't even want a locking diff in the front on a part time 4x4 with irs. its like putting a hammer in there. its just going to bang around in there until it breaks something
I know a few guys that race SCCA prod cars & prefer the welded diff's. I imagine there is some major setup changes to make to get it to work, but I know some guys who make it work ;)
I have a quaife in my HP Rabbit. Its nice, but it will act as an open diff when there is no torque to sense (off camber corners, wheel in the grass) - Might not be good for hill climbs.
Kendall
It's fun watching the guys with locking diffs offroad. They lock up that front one and suddenly straight ahead is the only option. Gotta be quick on unlocking them sometimes...
Had a friend working with a couple, instructing them on how to improve their driving in their 510 prod car.
The wife was a great listener and followed his instructinos to a T, but was struggling and struggling getting the car to turn in when and where she wanted.
Eventually after much discussion with the husband (discussing rear end gearing) it was discovered that the diff was welded. The instructor asked them politely to try changing to an open or a limited slip differential.
Once the differential was swapped, the drivers started running over curbs all over the track. Once they got used to the car turning in with appropriate gusto, they gained a couple of seconds a lap.
Just because a bunch of racers use a product or adjust their cars a certain way to make it work for them (or they get used to it), doesn't always make it correct for you. Sometimes it does, but sometimes it becomes a case of "rubber ducky syndrome" Where someone shows up with a rubber ducky on their dash and starts winning, shortly thereafter everyone else starts putting rubber ducky's on their dashboards, etc.
Welded diff's are for people too cheap to buy a better limited slip or are incapable of adjusting their driving style or suspension to compensate for corners.
Thank You!
I will - with all the effort in my body - avoid welding my front diff.
I Love this bar!
My buddy used to race 1st gen tercels, full-contact mini-stock on dirt.
We got the bright idea to weld up the diff one day.
I was crewing for him in the next race, the track was dirt with a couple hundred feet of pavement in one corner.
When he pitted his suggestion was to take the money we didn't spend of a LSD and buy a coffin.
Shawn
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