I'm still toying with the idea of building a budget E30 track cay and was just thinking about Diffs...

Is a welded diff a useful mod for a track car [as opposed to an expensive 'proper' diff]? Or is it a drifting only modification?

What are a welded diffs characteristics?

 

think about what a diff is for,,,, then think how a welded diff will act

 

wield diffs are 4 stock cars

 

I know what a diff is for etc...I'm sure I read somewhere about people using welded diffs on track though....the only real problems coming during slow speed/tight manouvering etc...

Or am I wrong?

 

yes your wrong

 

like you knwo the diff is to allow a speed difference detween the two wheels! the outside tyre traveling further/faster than the inside!

if we remove the abilty to for this speed difference we MUST has something else slipping! the tyres! meaning a lack of grip for the inside tyre

 

but damn excellent for drifting

 

my friend owned a gsi3000 which he drifted everywhere! the diff welded itself solid one day!

Much fun was had from that point on

 

and donuts too

 

I've been toying with the idea of that for the E30, but i've worked out that its not my diff thats shagged

 

whats shagged,,, your driving technique?

 

nope, nearside rear wheel bearing - there is no knocking when the car is on axle stands and the wheels are decelerating without using the brakes, but as soon as they are on the ground, there is a noise

 

just cool you found it mate

 

So long as you dont weld up that M3 rear diff im after

 

there are plus's and minus's, it's not as simple as gareth is saying.

if the radius of the bend is not that tight, the difference in wheel speeds is not that great.

what you can get with an open diff (or even a shit lsd like cossies have) is that the inside wheel doesn't have much weight on it because of body roll to the outside of the corner, so it loses grip and spins. with a welded diff that would not happen allowing you to power out of the bends quicker.

as said, many 'banger racers' or stock cars have welded diffs, and it's not just to make them look good is it? it obviously helps with traction to have both wheels driving all the time.

what can happen is that because you have such good grip at the back, when you power on, but not so aggressively as to initiate wheel spin and power oversteer (not a drift )the front can push wide in an oversteer situation.

if it's for track only, i would say do it. especially if diffs are cheap and you can swap them out easily. then try the difference and see which you prefer.

 

Thanks for that....I was sure there was another side to the story. I did some more research on the net which seems to back up your arguement

Plus they are good for drifting as well

 

they are in a lot of ways, but not necessarily for initiating the drift before a corner where an adjustable 2 way can be optimised. but for the money, well worth doing IMO

 

I thought you changed both the rear wheel bearings gracey?

Proper bitch of a job to do on a 3 series

 

just did the one, the other side appeared to be fine Chip - going to do it as soon as i can be arsed

 

The tools i used were:

homemade puller that looked like something from mad max
2 foot breaker bar
24 stone of mongo

 

Listen to Nick, and other people whos driven cars with welded diffs a lot.

Reality is very different to the rumour, trust me.

 

you still wouldnt want a welded diff as a track car!

 

i would maybe not if you're in serious competition, but as a trackday toy it makes it much more fun

 

if traction was limited id much prefer one over a open diff.

theres NO situations where welded diffs are better than a CORRECTLY set up (for the use/car/driver) plated diff.

but far better than open or standard viscous etc diffs in many situations.

 

traction isnt normally a problem on a track car

 

A race car maybe.
But not many RWD road-track cars with open diffs dont have traction problems! Ie nigh on every cossie on earth

 

an e30 rear axle is slightly more sophisticated than a cossie one though steve

but stop pussying about, and get the welder out

i'm a poet, and i didn't know it

 

 

I'm talking fun/track-day car on a budget here....

I.E. Open Diff vs 325i Sport LSD vs welded diff not race car quaife etc.....

The specific corner I'm thinking about is the hairpin before the main straight at Croft [as this is the only one I really have a traction problem with in my RST....just trying to compare].

 

you will get full traction out of a hairpin with a welded diff and fly up the straight, although you may have to turn in slightly slower.

even a hairpin on a racetrack is not really what i would call a tight turn that would give you trouble with a welded diff. nothing like the judder that you get trying to get in a parking space