Welded diff vs LSD

[minspd]

Has anyone run both a welded diff and an LSD, ideally on the same car?

Is an LSD faster?

Posted this question on trackhq but realized people here might be more helpful: http://www.trackhq.com/forums/f350/l...ad-racer-7796/

[jfryjfry]

A buddy did and his 350z on the track was useless compared to the vlsd he changed to

[RalliartRsX]

A welded diff will be under "lock" on all conditions (be it throttle on or throttle off, etc), so the car will always want to plow straight and understeer like a pig.

Good for "dorifto" but a terrible road coarse setup in anything but a good kart (literally).

[e1_griego]

Considering how many OS Giken diffs are on here, it's pretty easy to see how people have voted with their dollars.

[minspd]

A buddy did and his 350z on the track was useless compared to the vlsd he changed to

Was this on street tires or R compounds?

[minspd]

Considering how many OS Giken diffs are on here, it's pretty easy to see how people have voted with their dollars.

I should have clarified that I am interested in data for front wheel drive cars, which is why I posted in the Sentra forum. For rear wheel drive cars OS Giken does appear to be the way to go.

My 240 has a welded diff and the car is borderline unusable on street tires. Unquestionably unusable in rain on street tires. It becomes somewhat acceptable on R compounds but still slow. This is a drift car though with unknown alignment, for all I know it was set up to slide.

My Civic is very balanced with a welded diff and one thing I learned from it is alignment makes a big difference in the behavior of a car (http://winhpde.com/blog/2013/fwd-welded-diff/#alignment).

[e1_griego]

Oh lol, I use the 'new posts' button and rarely check which forum things are posted in.

My mistake.

[Def]

FWD cars do good with a welded diff if you drive hard into a corner, an LSD will be faster if you like a nice, smooth driving style on corner entry and mid-corner.

RWD cars with welded diffs are horrible on track unless you do A LOT of setup work to make it kinda sorta work. You can never really stomp on the throttle mid-corner to transfer weight, so it makes the "always wanting to come around" rear end even more of a pain to drive around.

[minspd]

Thanks Def. I don't think I object to aggressive corner entries :-)

Will limited slip help with tire wear?



(Top is the outside of the tire.)

This was with 3 degrees of front camber and I don't think this much camber is excessive. Front tires were rolling over with 2 degrees of camber.

[Matt93SE]

Yes, a limited slip will definitely help with that part.
Also, flipping your tires before they're that worn out will give you considerably more life. looks like the outer tread depth is at 40% or so?

[Def]

An aggressive limited slip will likely still yield lots of inner tire wear on a fwd car that's happy in corners. It's rough on tires putting power down with -3 deg camber, but that just comes with the territory.

[PDM075]

Drove a buddy's race IP3 (similar to SCCA ITC) Civic with a welded diff same day I had my STS (solo class) CRX out at the local track. My car open diff - fights to put power down out of any mid to slow speed corner - does the same at any auto-x - you have to wait to put power down on no R tires (STS class is 140 treadwear or higher until end of this year, and moving to 200 TW)

While the welded diff was clunky in the pits, once out on track it was night and day difference as to how fast you can get back on power and steer your way through the corner. His car heavier than mine, crappier suspension (standard off the shelf Konis vs SPSS units on mine - my car all Skunk 2 arms, with fresh bushings throughout and fresh motor with less than 1K on it) was able to run over 1.5 seconds per lap faster than my own CRX - so even a welded diff is worth more than it's weight in gold on a FWD.


On a RWD car - I hated it in my RWD 200SX race car. Pushed on corner entry and mid corner - not allowing you to get on throttle early.

Auto-x even a 1.5 way diff sucks for us - thus why most of us run OS Giken's. You can get away with 1.5 way on track, but it still pushes on corner entry.

As for tire wear, - rotate them more often. Track use doesn't really care much about direction - I've swapped everything around front to back, inside to out and couldn't feel the difference on a FWD car on the racetrack.

don

[Matt93SE]

Lots of FWD club racers use welded diffs. Gotta be on the gas at entry, but they're cheap and faster than open or viscous.

[minspd]

Yes, a limited slip will definitely help with that part.
Also, flipping your tires before they're that worn out will give you considerably more life. looks like the outer tread depth is at 40% or so?

I looked at the tires in person and they don't look as uneven. The "not worn" part seems less than it is in the picture.

The very outside edge of the tire probably has 80% if not 90% of tread on it.

That said, the tire does get used there, just very little. (Not for the lack of trying, I was catching everyone in corners.)

The wear in the picture was accumulated over a single 3 day weekend. It was not even an open track event, I figure I ran at most 2-3 hours per day.

[Stealthyfish]

I've seen fwd nismo diffs pop up for sale every once in a blue moon. Maybe an option for a bit of slip?