Welded Diff

[lam@xxxxxxxxxxxxxx (Ken Lam)]

<>Can a welded diff be used strictly for hard driving during track use?
>Or would I be damaging axles and stuff?  Possibly looking to buy another
>stock diff and welding the sucker solid(how is this done anyways?) and
>swapping it in/out on race days.  LSD with 25% lock-up just doesn't seem
>that it would offer $400+ worth of performance increase.
>
>Dan
>1990 325i Could be faster...

Dan,

>From what I have read, welded diff's take a lot of power to work correctly.
Without sufficient power to break the rear wheels loose under almost any
conditions, the welded diff' will lead to increased understeer.

This understeer is especially pronounced under braking.  The car doesn't
want to turn in because both rear wheels are forced to rotate at the same
speed.

Porsche did run spools (the equivalent of a welded diff') in their GT-1's at
Le Mans in 97.  But they have 600 HP and it was more in the interest of
reliability.  During the early 90's, when F-1 cars had traction control and
ABS, they ran basically an open diff',  which gave much better cornering
characteristics.

And yes, a welded diff' will put additional stress on the drive axles and CV
joints.  My friend tried a welded diff' on his ITB Golf.  He was performing
some "shake-out" runs at a local auto-x and blew two CV joints within 2
laps.  Granted, it was a much tighter course than a road course but you get
the idea 8^)>

How does a car corner without a differential? Basic physics dictates that in a
given corner the outside wheel rotates faster on travels more than the inside
wheel hence the need for a differential. As one digester posted recently he had
a lot of skidding and chattering from his tires as he tried to negotiate turns
in his car with a seized differential.  How is it Porsche is able to run a car
with a locked diff?

- -- 

kenny_lam@domain.elided

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