benefits/pitfalls of a welded diff

[littlered]

i want to do a bit of wet driftng as i now have a very smooth local carpark that i have sole permision to use,i wanted to know the benefits and pitfalls of having my diff welded/or buying a spare diff and getting it welded?
any ideas on price/how easy is it to change a diff?
cheers carlyle

[volvosneverdie]

ask oapem. Or look at his NEED GASKETS thread.

[SteveP]

Benefits:
- Easier to hold sideways and more predictable oversteer
- It's been said that a welded diff can hold more power, but maybe not applicable on a stock 1.7!

Pitfalls:
- Skipping of tyres on tight turns, and increased wear
- Arguably more dangerous on public roads in the wrong hands (if it loses traction it'll scrabble sideways rather than spin one rear wheel up)
- If not welded correctly, welds can break and jam against the outer diff casing and the diff innards

[OapEM]

^ As above. The inside wheel skipping is annoying and makes parking harder, also if you roll into a tight-ish corner (normal driving) it scrubs all of your speed off.

I also found it incredibly hard to drive with one hand lol! Esp. 3 point turns.
I have driven mine a few times in the wet and as long as you're not an idiot they are fine IMO (standing water may be the exception!)
It certainly does hang out longer now and is more controlled and my 360 will go in the dry on a lot of surfaces, but only if I ask it to.

As for price, I'm not sure. I think I have heard £50 mentioned as a rate for someone to weld them up. Mine was fully stripped and cleaned and then I filled the diff case with weld using my Clarke 175a on max settings, so I should have none of the usual worries about the planet gears rolling over poor welds and chewing it up (happened to a lad I know) on his 340.

The thing I found the hardest was to learn to trust it, as in putting the power down. Once you have overcome that though leaving 11's and nice long drifts are easy.

As for getting a spare, definitley. I intend to have one (open) as something to fall back on. It also means obvioulsy you can bstrip/build the car up much quicker. As when I welded mine I had to do it in two goes as I maxed out the duty cycle on the MiG and the diff case stayed hot for hours after! lol

Also, see Mac for on of his diff plate kits - gasket, new SS bolts and washers and sealing washers. just received mine and looks a top quality product. You can't get them from Volvo anymore, but even if you could I doubt they would be of this quality!

[pettaw]

Biggest risk is the welds not penetrating the planet gears properly and then breaking. We've had several instances of it on this forum, so locating a spare open diff is a good idea so you have something to fall back on.

Ideally IMO to get the diffs welded properly you need someone with a 3 phase industrial MIG rated at several hundred amps to get enough penetration, but it sounds like OAPem's done a pretty good job judging by his description maxing out his 175.

[Cutler]

Be aware that understeer might become a problem. It differs from car to car and i dont know about 360's.

So massiv understeer as basic setup and massiv oversteer with the pedal flat 2 the mat. Can anyone with welded 360 comment on that?

As I can't find a reasonably priced solution for a lsd i might as well look into welding up my diff.

[robinxr4i]

Can't speak for a 340/360 as every car reacts very different. I had a welded diff in my Sierra 2.0 and it made the car much better imo, okay it means taking extra care in the wet, the car skips/clunks on tight slow turna and wears out tyres quicker. But in every other respect it's a great modification, the extra understeer wasn't as noticeable as everyone makes out.

Basically open diffs suck, weld it and you love it!

[Cutler]

hehe, thanks for the reply. i've got a 2.0i sierra as a daily as well. maybe i'll weld it up too! but german mot regs do not favor welded diffs on none competition cars

anyone with a welded 340/360 with comments on the understeer problem?

[volvodspec]

understeer? no, definatly not.

the car handles like normal with tire squeel around tight corners. pedal to the metal corners result in oversteer, with less than full throttle it can happen too..
on wet it's pretty much the same story, though it will oversteer much sooner.

[Cutler]

Ok, nice to hear that. Will def. weld then!