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MGA tranny (Bill Spohn... ring gear, flywheel)

To: mgs@Autox.Team.Net
Subject: MGA tranny (Bill Spohn... ring gear, flywheel)
From: Carol <car@intersatx.net>
Date: Wed, 10 Jun 1998 10:55:47 -0500
<<My concern now is getting it back in.  Any advice on a different technique
would be greatly appreciated.  This was not an issue about the rig used to
pull the engine not allowing enough angulation.  The problem was hard parts
on the car grounding to hard part on the engine. >>

I've done many an engine change on As (my record was 8 in one racing season,
due to repairs, different class rules, etc.) and I always leave the gearbox in
place, for the reasons that you discovered.
You may have any easier time if you install the trans first, then put a
scissor jack under it and pump it up untill it touches the tunnel. With a
proper lifting rig it is easy to drop the engine in and adjust it so the rear
plate lines up with the trans, and then pop - it's in (well not always, but
sometimes as easy as that).

<<Were the crank and flywheel balanced separately or as an assembly when the
car was built?  A friend has a used flywheel with a decent ring
gear that he may be willing to part with  but I don't want to have to pull
the crank and rebalance just so that I can save the money for a new ring
gear. I would not mind saving the  money if there was no down side,
however.>>

Separately, so you can install a flywheel off another engine. If the gear
isn't really good, I'd replace it.

<<The ring gear is worn in a couple of spots only (typical of four cylinder
engines). I know this is crazy, but can anyone think of a down side to
just re-indexing the flywheel to put fresh teeth where the wear has
occurred.>>

I wouldn't go cheap on this - it will be in the car for a long time. You'd
have to drill new holes in the flywheel anyway to reindex. Might as well
install a new gear, so at least it will be close to balanced to start with.

<<I am thinking about having the flywheel lightened. Anyone have any
recommendations about area and amount to cut? I would have this done if
I choose to have a new ring gear professionally installed.>>

OK, now you really should have the whole flywhell balanced once you lighten
it.
Do you have the early one that is flat across the back, ie no cut-out area?
If you can find a 3 main B wheel, it is somewhat lighter. You don't really
want to go too light on the street. As I recall (don't shoot me if I'm wrong,
I'm dredging this up from the long-ago and don't have my notes here), the
stock early wheel weighs around 30 lbs, and the B wheel is about 26 lbs.
Lightening near the periphery will have the most effect.

On my A race car I run a steel wheel that only weighs about 13 lbs, and the
one on the TVR I run a rare bit, the homologated Elva Courier aluminum
flywheel (rarely see those) which as I recall is around 16 lbs. It does
seriously affect the idle, and isn't recommended for a street motor.  Around
22 lbs. works well for a bit more snap but decent smoothness.

<<Has anyone installed a starter ring gear at home? Any pointers that you are
willing to share?>>

Yeah - don't do this at home! It isn't that hard, but if you screw it up you
are out a ring gear. The labour is cheaper than the part is.Get it done
professionally.

Bill S.




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