I am about to fit an EARLY 12 and a late 1979 56A 4 speed into a KB10
the early motor never used the 3 mm backing plate but the 56A came from a ute using the backing plate

so should I fit the plate or not?
also any suggestions on which bearing carrier B C or D to use?

After its regoed it will get an A15 and 5 speed and I will use the backing plate,the "D" carrier and the 60 series clutch lever but that will take engineering.
For now I just want to get the 1200 + 4 speed in and licensed.
Thanks

Theres a good chance that I'm way off, but it was once suggested to me that the sandwhich plate is used to help loctae the starter motor. I've run cars without them, and the starter sounded terrible. (perhaps the sarter was just coozed?)

fair call
our Nissan engineers presumably had good reason to add that plate when they brought out the later A12

its also a way to distribute torque & power loads more evenly. if you dont use it you'll only have 4 bolts attaching the motor to the trans, with the plate you have at least another 4 tying the complete unit together.

Yes, as EDP says it is used to reduce NVH. However that is not the primary determination to use it.

The 56A is 3.5 mm shorter and so designed to use a 3.5 mm Engine Plate. But because the A14 flywheel is thicker than A12 flywheel, Datsun created a shorter Release Bearing carrier to make up the difference.

So:
* Two different flywheel thicknesses
* Two different transmissions lengths
* Two different release bearing carrier lengths
* Engine plate or no engine plate

Only certain combinations work to allow proper clutch adjusment.

DD wrote:
"The 56A is 3.5 mm shorter and so designed to use a 3.5 mm Engine Plate. But because the A14 flywheel is thicker than A12 flywheel, Datsun created a shorter Release Bearing carrier to make up the difference."

The Tech Wiki however, shows a 5mm thick plate. Which plates came on which combos? I'm building an A14 with a 60A Gearbox, the tech says I need the short carrier and engine plate, but which plate?

The tech wiki should be fixed. As far as I know the plates are about 5mm thick or about 3mm thick -- just an estimate. The two I measured are more precisely 3.5 mm thick. I believe they are all the same thickness, but I have not measured every plate.

So as far as you know, there is only one plate? Not different ones of varying thickness?

Sorry, didn't mean to edit your post.


Quote:

Yes. They look the same thickness. I measured an A14 plate and an A12 plate and they are the same thickness. That's all I know.

The Nissan factory service manuals do not explain the difference in plates, throwout bearing lengths, etc. Just many reports of some combinations not working correctly.

You can help by measuring yours, and posting the data here:
* Thickness of plate
* Length of release bearing
* Thickness of flyweel
* Transmission face-to-ball distance










Thickness?

on a12 and 56 boxes i've seperated they've only had the dust shield, not the full size backing plate, i guess this is because they've got the right combo of flywheel/carrier/length etc??