Tranny Mount Take 2- by Steve Heimsoth
I used an Energy Suspension polyurethane transmission mount on our racing 5 speed and will be using a Prothane mount for my street roadster 5 speed. As most of you know, the stock 5 speed mount is over $100 new. This is a more cost effective solution. The Energy suspension 3-1108G and Prothane 7-1604-BL are heavy duty polyurethane mounts with fail-safe interlocking cores. Either can be purchased for less than $25.
Energy suspension 3-1108G:
Prothane 7-1604-BL:
The transmission mounting holes on the mount need to be widened about 1/8" on each side in order to bolt to the 5 speed tail housing. You also have to trim the upper plate diagonally as shown so that the mount will clear the X-frame:
New holes inline with the old holes need to be drilled in the cross-member:
On the race car I used the bolts with the 3-1108G to attach the mount to the cross-member. I had to slot the new holes to allow insertion of the bolts sideways into the cross-member and then rotate up inside. I decided to try the 7-1604-BL for my street car because it has studs that can insert from the top. The studs had to be shortened by 1/4" and it is quite a trick to get the washers and nuts on. The finished installation works out real nice.
Note the weld repair on the tail housing boss. I have found many of these bosses are cracked.
Finished:
Since it is so hard to start the washers and nuts inside the cross-member, another option would be drilling the holes all the way through the bottom plate and then opening up the bottom plate holes so that socket head cap screws could be inserted from underneath. I don't mind the nut installation and should not have to mess with it again since the transmission will be installed with the cross-member on it.
_________________ Steve Heimsoth '69 SRL311 '72 S30 (240Z)