The backlash is not set with tooling. The tooling - which I have made myself
- is nothing more than a sturdy plate that can be bolted on to the opened
housing. It has a dial gauge mounted to it, which bears on the pinion. It is
not important to know what the distance is between the pinion head and the
axle axis, only that it can be measured in relation to the new pinion
position. That determines the required spacer thickness. The objective is to
get the pinions in exactly the same position.
The backlash is determined by the position of the ring gear in relation to
the pinion. Once the pinion is in correct position, the backlash is easy. If
you have not messed with the distance collars, it should be the same on the
new gears as it was on the old. The ring gear position does not change. Yes,
I know that the MGA gears are not dimensionally the same as the TD/TF gears,
but remember, these are not MGA gears. They are drop in replacements for the
TD gears. Only the number of splines on the pinion force a new flange.
By the way, backlash can be figured out simply enough, too. Since backlash
is simply the rotation one gear can go through without moving its mate, the
angular rotation at the ring gear can be indirectly measured at the flange.
Since we know that the flange rotates 5.125 times (on the TD) for every one
turn of the ring gear, and you know the ratio of circumferences ring gear
to pinion flange, one can calculate the ring gear backlash based on the
backlash measured at the flange. Just as an example, if you put a bolt into
one of the flange bolt holes, you can measure the circumferal distance
between clicks of the gear backlash. Since the bolt hole is at a radius of
1.4", working the math out tells us that the required .006" of backlash at
the ring gear is roughly equivalent to .030" at the flange bolt hole.
This is not a method described in Carl Cedarstrand's book, but is
mathematically correct. And it's a lot easier than measuring the way he
describes.
All this is well and good, but the job is not done yet. I'll let the group
know how things turn out. That is if everyone else doesn't beat me to the
entire supply of gears.
Regards,
Lew Palmer
-----Original Message-----
From: BJCJ1@aol.com [mailto:BJCJ1@aol.com]
Sent: Wednesday, December 02, 1998 5:19 PM
To: lpalmer@vanstar.com
Subject: Re: Brown & Gammons
If your going to do the gear change yourself,,,how are you going to figure
out
the backlash? I've been thru the book a 100 times myself already. I even
had
the whole thing apart. Actually easier to take apart then I figured it
would
be. When I read the book, it refered to a specail tooling jig, and I have
tried to find anyone withone, but no luck. Have you got something to figure
the backlash with?
Thanks
Bob
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