Dick,
Actually, the TF standard ratio rear end ratio is not that unreasonable. At
4.55 it is much more usable that the TD which used a 5.125 ratio.
I just completed conducting a differential workshop for our local club
members in which 6 of us converted to the 4.55 ratio from the original
5.125. I'm personally pleased as I have increased my speed by 8 MPH at any
given RPM. I can now cruise at 65 MPH by doing around 4250 RPM, which is
where I used to be at 57 MPH - about as much as I wanted to push the engine.
One could use the 4.3 gear set from an MGA, with some loss of hill climbing
ability.
To do the conversion is not a difficult process, I just takes a lot of trial
fitting and measuring. Carl Cedarstrand published a booklet some years ago
on the procedures. This is still available from Moss Motors. It details the
steps necessary to use MGA ring and pinion gears in a TD/TF rear end. I does
require changing the spacers to the MGA style, and some gringing of the
carrier bearing spacers. Overall, it's not a bad procedure.
Unfortunately, one cannot use the whole MGA rear axle, since it's way too
wide.
The most difficult part of the whole operation is being able to measure the
pinion head location. We did this by making up a pinion measuring tool. It
consists of a flat steel plate which will slip over the axle case half
bolts. From this is hung a cradle to hold a dial gauge which bears against
the pinion head, thus allowing you to measure the relative positions of the
original pinion and the new MGA one. I was surprised how well this tooling
worked.
The final option, of course is to have someone else do the conversion.
University Motors (Ada, Michigan) will do the change over, but it somewhat
expensive due to all the labor involved.
Whatever your decision, good luck!
Regards,
Lew Palmer
-----Original Message-----
From: Dick Dell [mailto:rddell@mindspring.com]
Sent: Tuesday, April 13, 1999 9:10 AM
To: mg-t@autox.team.net
Subject: TF axle ratio
Hello All,
My work on the TF is going well. New fuel pump and brakes
all around will
help the go and stop functions. Thanks for all the help from
the group.
Special thanks to Lawrie Alexander out at The British
Sportscar Center in
California for all his help by email. Wish we had someplace
similar here on
the East coast.
Next question now involves driveability.
I want to upgrade my gear ratio on the TF to something a bit
more
reasonable. I don't pull stumps much anymore so first gear
is pretty much
unuseable and highway speed just wrings that poor little
1250 to the limit.
Does anyone have any tips on doing a gear change? I do have
a spare MGA
rear axle that could be a donor but it's a wire wheel axle
and my TF will
stay a solid wheel car. Not sure about the possibilities
there.
Dick Dell
Raleigh NC
|