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TR6 Can I remove the shim on the rear gearbox mount [J-type OD]

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Steve1970

Steve1970

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I've got the prop shaft yoke tapping against the gearbox tunnel when I take a left turn (on take-off, under load, etc).
The u-join itself is only about 7 years old and probably has less than 1000 miles on it, so I don't think it is faulty.

More likely, after my clutch job, during which i replaced the rear gearbox mount, the gearbox now sits a bit higher, and thus the yoke is more able to hit against the tunnel as it flexes under load. (This is my working theory anyway).

I have noticed that the mount assembly for this gearbox (which is of the J-type OD variety) mounts to the frame with a shim in between (shim is about 3/8").
So I am thinking.. in order to get more gearbox tunnel clearance, I could just remove the shims and the gearbox+prop shaft yoke would sit about 3/8" lower.

Was wondering if... (1) has anyone NOT had these shims on their 73-76 TR6? and (2) does anybody foresee any really bad things happening (I am willing to take on risk that the drive-line may get thrown out of alignment, as I can always replace the shims if necessary).

Many thanks, Steve
 
Yeah, I'd like to see what you are referring to as well. I don't believe there are any shims in mine.

Cheers
Tush
 
I'm not seeing the shims in any of the suppliers' catalogs.

PO said this was a bit if a frankenstein car, maybe the shims was his way of getting the driveline aligned without replacing the gearbox mount.

Anyways.. I am happy to hear that at least some of you don't have the shims. Makes me feel a bit more confident about removing them.

Many thanks
 
Fyi, for reference, photos of shims attached (if my upload went ok)
 

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Hi Steve,

Never seen anything like that before...could it be due to the fact that you have a j type instead of in an earlier frame? Did you car come with Overdrive initially ( would have been an A Type) or are you retrofitting/upgrading from a 4 speed?

I know there are some differences in the rear tranny mounts depending on the year of the frame etc.

Cheers
Tush
 
ok great, thanks for confirming. going to re-fit the tunnel tomorrow after work then give it a good test.
 
Success (so far)!!
The driveshaft yoke/u-joint is no longer tapping against the tunnel.

She drives a bit differently now too.
The acceleration curve (over gear-shifting) feels little more flat than prior to removing those homemade gearbox spacers.
Under hard acceleration, I use to get a lot more accel in 2nd gear before shifting to 3rd. Now it seems I need to shift to 3rd earlier to keep the same level of accel.
Nothing wrong there per se, just need to get used to shifting into 3rd earlier.

Thanks again for the replies, feels good to be on the road again.
 
If you want your acceleration back make a shim about half the size or use washers to lift the tail shaft a little more and see what happens. Wonder if too much angle on the U joint is robbing power.
 
I had very similar spacers on my '74 w/ overdrive. But I also had some badly worn differential mounts too. When I pulled the trans to fix the clutch, I noticed the differential mounts and replaced them, and when I went to re-install everything, I couldn't fit those shims either. They've been out for almost two years now.

Tom
 
Hi Steve,

Do you have a measurement from floor pan to centre of Prop shaft? I believe I have a issue similar to yours but mine is due to the fact I have an A type OD fitted to a 75 model mounted on standard gearbox mounts.

Cheers
Andy
 
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