Datsun Roadster Forum-311s.org

Right, I looked at those and those of another vendor, and they look extremely similar if you flash back and forth between them or place them side by side on screen, but I still can't tell the offset of one versus the other. The holes look bigger on the 5 speed.

Any one have measurements? Anyone? Bueller? Bueller?
T

Update from the vendor. The motor mounts are virtually the same and there is no difference in offset of the four speed versus 5 speed mount.
So I am now stuck thinking it must be either the transmission is some odd anomaly, or the problem lies with the H20 Block and where the motor mounts are situated.
The same block, with the 4 speed mounted just fine, and the only difference has been the 5 speed transmission, the engine plate (thicker) and the 5 speed crossmember and motor mount.

Anybody have a thought - PLEASE come up with something simple!
I would love a slap your head moment about now.
Tom

Glad you were able to clarify the specs. What doesn't make sense to me is same motor with 4 speed with 4 speed mount and thin plate and 5 speed with it's mount and thicker plate both were in the same chassis from the factory. I forgot, is a 67.5 trans mount bracket like a 66 or a 68?

Thanks Dave:
That was one of my original questions, does anyone know if there is anything about the transmission mount, or frame bolt hole location, for a 67.5 that is different from the rest of the world or model years?

OK so I got back to it and found something very interesting, I think Sid alluded to this but here's what I think. There is a 4 speed mount that looks like a 5 speed mount!
So pictures below - am I nuts or are there more than a few crossmembers out there?
Here are the mounts side by side. One (torn up) is the old 4 speed the new one is a mystery mount.
At first blush they look VERY different, but upon measurement they appear to be the same "working" dimension, that is height form the frame and spacing of all bolt holes.
So my belief that I had a 5 speed cross member looks to be incorrect!
Any comments?
Tom

Also an earlier post listed the measurement of the holes on the 5 speed as being set back approximately 11/16th of an inch from the 4 speed crossmember. I measured how much the mounts were pushed forward with the incorect cross member and it was right at 1/2 inch of forward deflection.

The bottom one which I believe is the one you are calling a mystery mount is exactly like the one I used in my stroker 5 speed conversion. It is in fact a 5 speed mount. I do not recall having to do anything special to get it to work. The rubber mount that goes on top of it was still mounted to my 5 speed tranny when I put mine in. It has been a few years but with the correct pieces you should not have any issues.

Steve

Thanks Steve
When I bought the tranny and all the parts (at least 7 years ago!) this was supposed to be a 5 speed mount. But when I put this in the car, nothing lined up right. The shifter is too high and forward so it make sense that this is off somehow. Judging by Dbricks pictures, and other forum members, this mount should be about 1/2 inch high and the holes should be back about 3/4 of an inch.
Here are pictures showing the fit and the shift of the mounts.

who does the best 5-speed rebuilds? ie:person/shop most familiar with nuances and common wear areas on these transmission. any ideas?

SinrgRacing wrote:Thanks to 23yrRebuild, I have a very nice X-member for my 5-speed swap.

A couple pics and some details.

The 5-speed XM is shorter (1-5/8" vs. 2-13/16" tall) and moves the transmission bolt mounting holes aft (about 11/16").

The tranny mount is in front of the X in the vehicle frame, thus the shorter of the trapezoid sides is aft. Note that the transmission mount is also different for a 4-speed to a 5-speed.

After reading this thread, I guess I have to do a custom mount for the 5 speed conversion on my 66. There's no mounting holes underneath the frame like later cars. My cross member is completely different from the pictures in this post. It is mounted on the side of the inner frame.

Nope,

No custom mount needed, just drop your existing, stock, early mount downward to use only the bottom row of holes. This is accepted practice that is described in the 1600 Competition Manual, among other sources. I'm also one of those people who is currently using that arrangement. I decided to use Grade 8 bolts though.

23yrRebuild wrote:Nope,

No custom mount needed, just drop your existing, stock, early mount downward to use only the bottom row of holes. This is accepted practice that is described in the 1600 Competition Manual, among other sources. I'm also one of those people who is currently using that arrangement. I decided to use Grade 8 bolts though.

Thanks, I just read up on the competition manual.
Did you need to drill any new holes?
From this thread, it kinda throws me off and worry about the stress on the motor mounts.

The stress on the motor mounts seen in my original thread was because the wrong mount was used initially, forcing the engine mounts forward by 11/16th of an inch. The correct mount resolved this.
The solution discussed above for your earlier model seems to address this fix as correct, and should not add this type of stress onto the engine mounts. My $.02!

Thanks for clarifying...
The engine should be in the bay by tomorrow, I will take some pictures.
Thanks again..

Pix? I'm curious how this turned out!

Cheers
James