I dont understand how you can say less chance of breakage. People go on about metal properties and how the heat effects the gear metal. How many of you have actually welded a diff let alone driven a car with a locker? Would be interesting to know.
If you can weld properly and get good penetration with the weld, there is no reason the welds will break. You only need to weld in all four corners on each side. That means there is eight welds plus the gear faces that are still touching, taking all the load.

Tailshafts are made of thin tubing and are welded at each end to a uni. Do you think a tailshaft maker is going to heat a sealed airtight tube to condition the metal? So how does the thin tube right next to the weld that has had its properties changed as a result of the welding survive the twisting torque applied to it.

I know and understand about metal properties, but to say " If you weld a diff, It will fail." Is bull.
Bridges are built out of metal everyday. Structural welds are done on them everyday. Do they heat treat those welds?


At the end of the day. For a street driven car any form of locked diff is only fun for spinning 2 wheels.

my mate has a mini spool centre in his r31, performs just the same as a welded diff but less chance of breakage. Go for the mini spool they dont cost much.

Quote:

well said, i agree 100%

And to who ever asked about the axles, they will break alot easier with wide/tall tyres on the car than they would with standard/skinny tyres.

thanks guys for such great replys.
Yes this is for a street car
Yes hopefully it will see the track sometimes
No its not a full-on dragster

after much thought and crap i have come to the same conclusion i have started with......i cant have an open wheeler but dont want a locked diff... so i need an LSD. and with the option of VL and thoes other falcon LSDs im sure i should be able to find a relativly cheap one.
Any hints on where to look.....or anyone got one they wanna sell me?

Thanks again
Elliott

Point taken pro-240c, I thought he was looking for a budget application for the street.
I was mainly talking from all my experience with diffs in competition rallycars not big dollar drag build ups where I have no experience. Very dependant on the application I guess.
I can understand the use of a spool for drag applications - live and learn

because "welding" the centre changes the metallurgial properties of the centre.

we're talking about hi-tensile material here, so to make the weld a "proper" weld and completely failsafe, after welding you need to heat the whole centre up to a dull orange and then let it cool slowly. then heat it up to an almost yellow colour, then let it cool slowly.

then the weld will be of the same quality as the surrounding material.

welded centres in frequent drag racing use WILL fail - which is why all the top guys use full spools. you don't want a weld to bust under full power and transerring 90% of the load to the unbusted weld, which makes the car lurch sideways, then makes that weld bust and then the car swings the OTHER way and then you are back to a single spinner with bits of weld floating around inside the housing running the risk of them jaming the gears and porviding full rear lock up - - - all at 100+mph.

Some info re spools and welded lockers.
A welded diff centre basically behaves the same as a spool centre, they both provide a way of giving direct drive to the rear axles.
They both also put lots of load on the rest of the driveline, especially gearboxes and axles, the problems usually show up if you are thrashing the car through tight left then right corners where lots of steering lock is required. When you hear things like "you get axle wind up" then those loads have to go somewhere and it usually transfers the loads to other driveline bits. Ever herd the common "wanted to buy" AXLES because someone runs a locker on the street
As for having to replace both axles if you break one with a welded centre - what a load of sh1t. You weld the diff centre not the axles
All this points to why manufactures put LSD's into production cars, they are usually a way of transfering power or torque smoothly and progressively without sending large shock loads to the rest of the driveline.
I can not understand why someone would buy a spool when a cheap welded centre will do the same thing.

Quote:
An EA or EB Falcon LSD will fit straight into the R31 diff housing - that's what I'm using.
VL Commodore too & I think some later models....... VN / VP but you'll have to qualify that.

Hi Elliot
I have an R31 LSD in my 1200 ute that I race on a regular basis. They are actually quite strong and also cheap to rebuild. I have been told by several people that the cones are still available new from Nissan for $90.
I know of an RX7 drag car that does 1.3 second 60 foot times that is still using the same diff as mine and has never needed a rebuild.
Have you thought about buying a wrecked or cheap R31 Silhouette, pilfering the diff and then selling off the panels, motor, alloys etc? You will probably come out ahead dollars wise.
Regards Matty

i know i would rather an LSD over a locker for sure but if its goin to cost me an arm and a leg i'll probably just weld it or mini-spool it.
so can anyone tell me if later model falcon LSDs will fit straight into the 28 spline r31 borgwarner? or will i have to get the skyline LSD?

Thanks for all your help.
Elliott