Rich-
I changed differentials in my Vixen, and went through a fair amount of
effort in the process. I considered the TR4A unit, but the input was so
far off center that I decided on the Salisbury (and I agree with John's
reasoning as well).
Either one is significantly bigger than the Spitfire unit, and heavier.
The Salisbury is exactly 100lbs, the Spitfire 50. You will have to cut a
triangular hole in the floor of the body to fit the new unit; it won't
fit between the side frame rails.
A new or reworked driveshaft (shorten and fit a new differential flange
on your existing one) is necessary. Take measurements and buy from a
driveline specialist; ask at your local speed shop or auto parts store.
You'll need to fit the proper flanges, so bring the new unit and/or
EXACT measurements to them.
The new unit will likely require some trial fitting. When you get it
in, then measure the driveshaft and halfshaft centerline lengths for the
driveline folks. Remember to measure the short and long lengths of the
halfshafts to allow for wheel movement! You MIGHT be able to use the
old units; I couldn't. Compare the flange-to-flange measurements of the
old and new differentials; if the new one is significantly wider, you'll
need shorter half shafts.
I had to cut all off all the oem mounts from the car for the Salisbury,
and hard-mounted it directly to tabs I welded to the frame. Being a
race car, I didn't care about gear noise transmitted to the interior. I
have found that whatever noise it makes is masked by other sounds from
engine and exhaust. You can decide for yourself whether it's important.
I had a Detroit locker in one of my (many) spitfire units, and it wasn't
acceptable. It slammed in and out of lock on the street, and on the
track it stayed in lock and caused excessive oversteer. That's one
person's experience, just file it for reference. My Salisbury unit has
a standard limited slip set loose, and works well. Torsen is available
from Quaiffe.... I can dream, can't I?
All the work was done with the body ON the car. It's significant work,
but highly satisfying once it's done. Any questions just ask; I'll
answer if I can.
Best,
Skip Gurnee
70 Vixen (highly modified)
Rikrock@aol.com wrote:
In a message dated 01-07-03 12:14:42 EDT, John.Ayer@PSS.Boeing.com
writes:
As long as your are cutting and welding, would it not be just as easy to
change over to a Salisbury/Ford? Which would offer a greater range of
ratios
and limited slip devices...
If I were King, that's what I would do :)
Hey!
The Salisbury or the Z-car diffs are very good ideas. BUT, it just so
happens that I have a 4.55 Detroit Locker all set up, ready to go! It's
from
my old racer, a 1965 TR4A-IRS. We used it in the 2500M hillclimb car
for a
couple years, removed it when my buddy sold the car, and it has been
sitting
on the shelf for a couple years, waiting for the next assignment.
So, while it may not be as good as the others, it's a pretty sturdy
unit,
still in great shape, the gear ratio is just the ticket for
hillclimbing,
and........... the price is right!
Rich Rock (not a member of the lucky sperm club)
Pottstown, PA
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