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I've raced the past few years with an open diff (ITA crx) and am planning on using a welded diff for the upcoming season.
I likely won't have much opportunity to practice with it beforehand, so I'm wondering how my driving technique will need to be altered, and what to watch out for.
I've gathered that turning is much easier when you're on the gas, and braking is much easier when you're not turning.
What kind of craziness should I expect in the rain?
Never lift.Quote:
<font face=\"Verdana, Arial\" size=\"2\">tips for going to welded diff after driving an open diff </font>
Turning IS NOT possible unless you're on the gas. You gotta be good at pulling the trigger early if you're going to go to a welded diff.Quote:
Originally posted by Chris Sawatsky:
I've gathered that turning is much easier when you're on the gas, and braking is much easier when you're not turning.
Start an upper body workout program. Think "Popeye".
But Greg,
I thought that's the way I was supposed to drive, no matter what kind of diff I had?
http://Forum.ImprovedTouring.com/it/biggrin.gif
Actually, I am interest in this same question, but from a RWD point of reference.
Our Miata has an open diff and I get very significant wheelspin on tight right handers (which happen to be the ones preceding the two long straights at Rd.Atlanta). This obviously kills my momentum and exit speed. I've thought about a welded diff, but I have no experience on what to expect. Changing the assembly in the Miata is easy enough that we could swap them back to the open diff for wet races.
Any comments from the RWD crowd?
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Ony Anglade
ITA Miata
Sugar Hill, GA
RWD is no sweat, car should drive fine in the dry, slightly more difficult in the rain. It doesn't turn as well in the paddock which isn't a problem unless you are pushing it by hand
Ask if any one has issues with axle/hub/U-joint failure using welded diffs on IRS. I know of it happening in other cars, but have not heard anything specific on the Miata.
I've only run solid axle cars with one, with no problems. I theorized that the lack of damage was due to the inherent lifting of the inside wheel (reducing stresses on the drive line) caused by levering forces, which are not as strong in the IRS.
Because one is able to "upset" the car on corner entry, solid axle cars are not too difficult to drive. A combination of actions, in concert, with the steering wheel and throttle will get the rear loosened up. and the front end biting to allow the rear to rotate. Practice will fine tune the technique.
I've never driven a welded IRS, so I have nothing to offer here, I'm sorry.
Good luck.
Bill
For the rain, swap the box back to an open or LSD-equipped one.
Sort of diabolcal, especially under braking in the wet.
Otherwise, carry extra spare half-shafts and have fun!
Used to run a welded diff in my BMW 2002 ITB car. Tried a clutch type LSD, didn't like that. Tried a Quaife, really didnt like that. Kept on coming back to the trusty, cheap, consistant welded diff. The car would tend to understeer going into the corner and oversteer coming out of the corner, but it was consistant. I could also be more aggressive entering the corner because trailing throttle oversteer was less of an issue. On high speed sweepers the welded diff could hurt you because if your not going fast enough to drift, then the car binds up because one wheel has to slip for you to make the turn. Another item in the plus column is, you can dial in more rear brake because it's impossible to lock up one rear wheel. The strange thing is that on both of my 325's e-30 and e-36 they seem to prefer the clutch type LSD. I think it has something to do with tire size and center of gravity, in that the old 2002 has very little grip on the unloaded wheels when cornering. I think the bottom line is to test back to back. But I'll bet if you tried three different diffs the order would be: LSD quickest, then welded and last open. Sorry for the long rambling response. I hope it helps.
You'll dig the FWD car with the welded diff in the dry. Just get it up on a plane and you won't even notice the increased steering effort, I'll bet. The great thing is that you can turn the wheel, step on the throttle, and the nose of the car will go where you point it. It won't be as FAST as it might otherwise but you can tighten or widen a line at will - and at any speed up to the point where you are completely unhooked.
In the wet, it's like steering a fast boat - you don't want to try to correct every little direction change or you'll get behind and go skipping across the countryside. Let it have its head, accept that it's going to be a little darty, and ride it out.
K
Chris, here is what we found FWD Quaife 1.0-1.5 sec a lap faster and no more sawing on the wheel out of tight coners this was a Rabbit. RWD Pinto locked diff 1.0 sec or so better once you get used to it. BMW racer still blew by in his 2002! Never had eiter in the wet though. Glenn
So just like driving to work every day in winter on the balding tires on my daily hehQuote:
Originally posted by Knestis:
In the wet, it's like steering a fast boat - you don't want to try to correct every little direction change or you'll get behind and go skipping across the countryside. Let it have its head, accept that it's going to be a little darty, and ride it out.
K
Thanks for the tips and advice everyone!
Went to welded Diff in my Golf. Loved IT! cut 1.5 Secs off lap times. Broke a few axles and control arm. If it rains PARK IT! Not worth balling it up into little pieces.
well after racing my first weekend on the welded diff, with both dry and wet days, I love it.
traction was great in the dry, and my laptimes were dropping like crazy, though I don't have any solid numbers yet, I had about half a track lead on the guys I usually race with.
It wasn't all that bad in the rain either.
I did break an axle though! Good thing I brought spares
Chris, I have only lost 1 CV joint in 6 years of racing with a locked front diff. I do change out the entire 1/2 shafts, hubs, every year, but haven't broken an axle yet.
P.S. I broke more stuff on my Rabbit autox'ing it with an open diff than road racing it with a locker.
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Tim Linerud
San Francisco Region SCCA
#95 GP Wabbit
http://linerud.myvnc.com/racing/index.html