remydrm

so i did a search and i saw the same answers to this question every time. the same people too, and they always go a little of track. I wanted to know what people think about a locked welded rear diff. this would be for the road course only and NOT for street or drag!!
Is this a stupid idea or could it work out to make a great driver faster? (not me )

SonicRaT

iTrader: (6)

If it was professionaly done, and a *real* locked differential, I'd say ok, but if you're thinking of just taking it out and getting someone to weld it together hell no! My dad was crazy enough to try that once, the weld blew apart and ripped the hole rear-end of the car apart.

remydrm

but at first drive was it any faster around a track or would it have been had the welds held up?

SonicRaT

iTrader: (6)

It's not that great for a track, particularly because you smoke your tires around every corner because both wheels are spinning just as fast as they can, and as you know, during a corner, the outer wheel must travel faster than the inner wheel, thus, your inner wheel will burn up from slipping as the outwheeel travels at the same pace (usually slower becase your car ends up loose) In a drag situation it'll do damn good.

NZConvertible

Yep, this is for drag only, not the track (and definitely not the street).

DaveB

Very interesting...........

I have run a welded rear in my 240Z since 1990, and have not experienced any real problems with tire wear on the rear. There is, however, a different driving style with a welded rear as opposed to a LSD. With the welded rear, you must understand how to rotate the car in a tight turn as opposed to just driving it around the turn.

The GTUs has a Torsen rear, and the Sport has a clutch type LSD which are also different in feel and require attention to driving style.

If you are concerned with tire wear on a race car, relax. If you are dricing the car at 10/10ths, the difference in wear couldn't be more than 5%, which is so small, it is not noticeable. It's the cost of being fast.

Be sure to have a qualified welder with correct equipment do the work for you. Be sure he understands how to weld hardened steel, and make certain that the spider gears are welded SOLID.

Is a welded rear faster that an open one? You bet!

best of luck,

db

White_FC

I disagree a bit here..
I can't see why nearly all the improved production race cars (in Aus. dunno what that type of class is called elsewhere) would run welded diffs if it wasn't good for the handling of their cars.

SonicRaT

iTrader: (6)

I've never seen or heard of any race class involving handling (cornering specifically) EVER use welded rear-ends. Physics just doesn't agree with that idea.

White_FC

Well I have... and believe me I've seen many cars with locked diff's that handle quite well..

Possibly some sort of LSD might be better in some circumstances i'm sure, but on a cost/handling ratio I think the welded diff would come out on top of the LSD.

I really don't see there'd be much difference in handling between a tight LSD and a locked diff at any speed over parking speed anyway.

Rxmfn7

iTrader: (4)

Can someone point out the differences in the S4 clutch type vs the S5 viscous LSDs? I know how they work, but wondering whats the main differences in how they will act. Will you be able to really tell a difference? I have a stock S4 LSD in my GXL, and am about to swap in a 89 GTUs rear diff, for the 4.3 gears. I keep hearing alot of people say that the viscous sucks, and was wondering if that is true, and why?

remydrm

DaveB, can u go into more detail as you have this done. what is the rules to the race class , can those cars have LSD and they chose to use welded? Or are they non LDS cars that are allowed to yse welded?

tims

most road racers that run "welded" diff's do this because the car doesn't or didn't have a LSD available. it is a cost issue for most. it is simpler and cheaper to have a qualified welder weld the spider gears together than buy an aftermarket limited slip. this is a very common setup for rear drive IT type cars. the driving techniques are different but it will be faster than an open diff for sure.

DaveB

Tim is correct. I chose to weld the rear on the 240Z because the LSD was quite expensive at that time, and I was a poverty stricken new racer. I ran an open rear for 1 season and didn't like it at all. After welding and getting used to it, I was significantly faster(5 seconds a lap at Mid-Ohio)

SCCA rules for IT allow any LSD or locked rear as long as it fits in the origional housing. Gear ratio is also free.

As Tim has already said, it is a very cost effective means to go fast in a rear drive car. I have no experience with locked front drive cars, so I couldn't speak to that issue.

Just be sure that your welder understands how to weld hardened steel. I learned that the hard way...........

db

remydrm

now thats some great info , thnx
last question: what would you prefer in a gsl-se, the stock lsd or welding it locked?

thats the last 1 I promise!

thnx

DaveB

The enduro car that I drive is a 1st Gen with a welded rear. I have no experience with that body with LSD, so I would be afraid to offer an opinion. If your LSD is real tight, I would think that you might try it first and then make a decision as to whether you want to move from there. In the meantime, you might look for another non-LSD to get welded up to pop in at some time to try it out. It shouldn't be very expensive.

Have fun!

db

cloead

fghh

remydrm

fghh?

tims

the LSD if in good working condition will be a better setup. the welded diff tends to understeer on turn in since the car will not want to rotate, slow corners will show this the most. the LSD will help the car rotate since the inside wheel will be able to slip and turn at a different speed than the outside wheel(like the open diff), but will lock up when the power is applied. with the correct setup a good LSD should help the driver go faster easier. but since most first gens have a tendancy to oversteer anyways I would remove the diff from the car and if it is in good condition have the welder do his work and go racing. A LSD from the junkyard will not be a significant improvement over the open diff. for racing it will need to be in very good to new condition and then properly maintained and serviced after it is installed. Weld the diff and spend the money you saved on a test day to see how the car works with the new setup.