While I agree with the points you are making about "spreading the load"
and how jacking is not pushing up on the diff studs, I still don't
think it is a wise choice. The rubber biscuits that mount the diff fail
too soon as it is. The act of over-compressing them to lift the car can
only add to the gradual compressed shape that they take on. The excess
play in the diff mounting that results would increase the movement of
the diff whenever you shift/accelerate, and since the hammering that
the diff gives the mounts is what causes mount failure, the results are
obvious. Using poly diff mounts helps stave off early replacement, by
why take any chances. I jack from the frame with a 2x6 pad.
Bob Kramer, Austin TX
Hill Country Triumph Club
TR6x3, TR250 x3, TR3A vintage race
> From: Justin Wagner <firstname.lastname@example.org>
> To: jonmac <email@example.com>
> Cc: firstname.lastname@example.org; email@example.com
> Subject: Re: New lister, query on TR6 jacking
> Date: Saturday, April 04, 1998 5:03 PM
> jonmac wrote:
> > John
> > Many people use the diff for lifting as it is central. That does
> > it is a wise thing to do. There's a risk you might pop the diff
> > bolts through the top of the chassis....(snip)...
> I would differ with you on this...
> When you jack up the differential... you are NOT jacking up the
> studs... you are jacking up the BUSHED differential... which spreads
> weight across the structure very nicely... with little stress on the
> studs themselves... In edition, there is not much SHEER strain on
> when lifting.
> The stresses encountered by the differential and it's mountings,
> jacking, are far less than anything they encounter on any given drive
> around town, with speed bumps and potholes... If jacking your car by
> differential causes a mounting stud to "pop" through the chassis...I
> would say, "BETTER TO FIND OUT NOW, THAN WHILE DRIVING AT SPEED, ANd
> HITTING A BUMP"...
> Jacking "side to side"... takes time... and I would argue, the more
> messing around one does while jacking a car exposes you to more
> danger... and it is human nature that people will tend to try to
> things up, by going up in higher intervals... leaving one side of the
> car jacked up inches higher than the other...
> Which again... exposes you to yet even more danger... AND... for
> concerned with damaging there car... this does put a lot of strain on
> the car when flexed like that.
> I've jacked up TR 4A's, in the rear, with floor jacks under the
> differential since 1977. I never experienced a broken stud... (on my
> IRS) about 8 years... nor do I have any problems with my solid axle
> 4A... (When IRS studs snap... it's because they're rusty and/or
> have a stress fracture, etc.) And my brother and I, the mechanics in
> the family, have jacked up the family cars over the years... 280zx,
> Jensen Heally, Jaguar XJ 6, Corvette Stingray, Mustang Mach I, 280 zx
> Turbo, TR 7, Camaro, Ford LTD. Station WAgon with 429, and more...
> by the rear differential.
> Jacking by the differential is safe. Safe for the car, safe for the
> under the car. My humble opinion... others are welcome to comment.