I can't offer comment on the spicer, but the detroit locker is not
well loved by most LBC folk. It is pretty brutal in its transition between
freewheel and locked. Sudden big oversteer, and broken axles are
the most common complaints.
I've tried the quaife and the trannex, my vote goes for the trannex (a
clutch-type unit).
As for welded diffs, I have used one on a road race circuit and it was
certainly much better than an open diff although slow tight turns took some
time to get used to (severe understeer on turn-in). I also tried it on a
hillclimb (very tight and twisty) and while I was faster on some sections
it was slower overall because of the turn-in. My guess is that with more
practice and an adjustment in style I could have ended up faster, but
given how hard it is on the car, I decided it wasn't worth it and I'll hang
on for that trannex I plan to buy.
Mike
-----Original Message-----
From: Barney Gaylord <barneymg@ntsource.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: Tuesday, August 11, 1998 11:54 PM
Subject: Re: Why new leaf springs may be a waste
>At 12:39 PM 8/12/98 -0700, Mike Gigante wrote:
>>
>>>>3) LSD
>>>
>>>.... Lysergic acid Diethylamide .... Somehow I suspect you are refering
>to something else?
>>
>>Indeed, I am referring to a Limited Slip Diff.
>
>Oh yeah! I would dearly love to install that LSD. I would also like to
>use wider wheels and a larger engine, but alas, such luxuries are not
>allowed in Stock class.
>
>>If you are lifting the inside rear, .... Note that the common Quaife LSD
>will not work in this situation.
>
>You know, I hadn't thought about it in that light. But I suspect you're
>right, that the all gear and no clutch Quaife LSD would just free wheel
>with one tire off the ground. Hmmmmm. Brings up my next problem
(question).
>
>I am considering going into Street Prepared class with SCCA, where legal
>mods would include LSD, wide wheels, lowered suspension, larger carbs,
>exhaust headers and the like. I have been collecting parts for a while and
>am currently looking for a LSD. I was real high on a Quaife unit until
>this comment rang the bell. One of the quaint characteristics of a Quaife
>LSD is that if you jack up car and turn one rear wheel it does indeed free
>wheel, and you can't tell that the LSD unit is in there. (Just in case
>someone wanted to sneak one in unnoticed.) It doesn't take a lot of
>resistance at the tire to make it work, but it does take some, so you do
>have to keep both rear wheels at least touching the pavement.
>
>So now the question. Someone is offering me a couple of LSD's, one Spicer
>and one Detroit Locker. The only LSD unit I have any hands on experience
>with was a Ford Traction Lock unit in my 1974 Mustang, and I have certain
>reservations about that one. I'd appreciate any info anyone can supply
>about the workings of these LSD units. What works and what doesn't? Parts
>and/or service environment? You get the idea. What does anyone know here?
>
>>....
>>Again, it may not be allowed (but it was a BMC catalogued item at least
>for the spridget).
>
>Alas, never a factory option for the MGA that I know of, only available as
>an aftermarket part, so not allowed in Stock class. But I'm still
>interrested in LSD for the future.
>
>>BTW, you can also just weld up the spider gears in the diff to give
>yourself a permanently locked diff. It is hard on the axles though and
>causes understeer on turn-in.
>
>Yeah, strictly dirt track stuff. Makes tight turns very difficult on hard
>pavement.
>
>>>>4) stiffer rear shocks (very stiff bump damping before 'blowoff')
>>>
>>>.... can continue to wheel around on three like that until it slows down
>or completes the turn. ....
>>
>>Aaahh, but it does help. It helps a bit earlier in the process. By
>increasing rear damper stiffness you will get less roll on the transients
>at turn-in. .... As a result of reducing transient-induced roll (i.e. the
>lurch on turn-in), you may find you no longer lift the rear wheel. This
>works well for me.
>
>Yeah, I know what you're getting at. But, with experience I have nearly
>eliminated "lurch on turn in" by judicious use of soft feet, slow hands and
>smooth driving. Even with a very gradual transition into a tight 180 at
>less than 30 mph the rear wheel will still lift, like big time! If it was
>just a couple inches of bounce followed by immediate touchdown, then
>stiffer shocks might help a bit to surpress the lurch. What I'm talking
>about here is enough body roll to affect a complete long term lift, not
>just a lurch.
>
>>Finally, as someone else noted, if you re-arch the new springs to be at
>stock height, how can anyone complain?
>
>They can't. That would be perfectly legal. One problem here is that no
>one is likely to know what the correct ride height should be, as it is not
>stated anywhere in the Factory Workshop Manual, and I haven't found any
>other source for that information. Perhaps that spec never existed. Who's
>to say what it should be? This could lead to some intentional hedging on
>the extreme side of dimensional tolerance.
>
>I fully expect that my new springs are too tall, because under normal load
>conditions there's only a short downward travel available in the rear axel
>before it hits the limit of the rebound straps. And I suspect that the old
>springs are a bit too low, just because of the general appearance of the
>height of the car compared to other similar models. But either of these
>impressions could be wrong.
>
>If there is indeed no spec for the ride height, who can say what "out of
>spec" is? If the springs sag a little in normal use over the years, and
>that is normal and expected and part of the original design of the vehicle,
>then the current (lower) height of the old rear springs could be argued to
>be perfectly normal, stock, within spec, and legal for Stock class. Or,
>can anyone out there come up with a printed spec for the ride height of an
>MGA with a definite stated +/- tolerance or a max/min dimension? This is
>not just a rhetorical question. I really would like to know.
>
>Barney Gaylord
>1958 MGA with an attitude
>
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