Here we go Experts, time to school me in Adapter Plates.

I understand the basic idea, making a plate that goes between the transmission and the block to mate foreign parts together, but what are the basic rules of thumb?

Does the bellhousing on the tranny have to be smaller/bigger than the bolt pattern on the block? does it matter?

Lets say the plate is 1inch thick, wouldnt that set the transmission 1 inch further away from the block and mess up clearences with the transmission shaft making it to the clutch?

What is the basic plan of attack as to constructing one of these? Get a sheet of steel/aluminum, trace the bell housing pattern on one side, and trace the block bolt pattern on the other then drill holes? What else is there?

Hi Clay having just done this to mate a Nissan engine to a Toyota trans . I can give you some pointers .
The most important thing is that the gearbox shaft should be absolutely in line with the crankshaft . that is the principle but the practice is abit harder . I am useing an auto so it makes things abit easier . what Idid was to first get apiece of 4 mm steel plate and using the spacer plate from my engine I cut and drilled it to fit the block. I had a mate of mine adapt the nissan flexplate to attach the toyota torque converter . Then I sat the engine on its nose and lowered the gearbox onto the converter and after a bit of work I could drill the plate for the mounting bolts.
the spacer plate that matched the gearbox provided the template for gearbox mounting holes . some of which I tapped others bolt through. any way a couple pf photos might explain the proceedure . firstly the adaptor mounted on the block before working out the gearbox position , secondly sitting the box in place and marking a couple of reference holes and thirdly the spacer plate from the gearbox bolted to the adaptor plate ready to drill some more holes to attach the box .
Rescued attachment adaptor 1.jpg

here is the next photo gearbox sitting on the motor .
You will see that I had to cut a chunk out of the bell housing to fit the starter which is on the opersite side to the Toyota .
Rescued attachment adaptor 3.jpg

and finnally here is a picture of the toyota spacerplate bolted to the adaptor so I would be able to get all of the holes oin the right place by getting a drill bit that was a SNUGfit in two of the holes I was ablle to establish centers for two of the holes and then acurately drill them using thebdrill press
Hope that is some help . I realise that you are more likely to want to ise a manual but if you can ensure that the gearbox shaft tip is a snug fit into the spigot bush/bearing then this method should work as arule of thumb you will probably find that if you use a clutch plate that goes with the gearbox and a flywheel/ preasure plate that goes with the engine it should work out OK
Rescued attachment adaptor 2.jpg

I think i understand the way you did yours, but now isnt the transmission 4mm further away from the block than it usually would be since there is 4mm of steel between the tranny and block? Does this distance not matter?

also, what if the bolts holding the plate to the block in your picture interfered with the bell housing you are using? Like if you were dropping the transmission down onto the engine and the bell housing was hitting the bolts that go into the block?

another question, lets say the bell housing you are using is smaller than the bell housing meant for the block you are using, bolting the adapter plate to the block would be easy, but to bolt the transmission up, you would have to thread the adapter plate for the bell housing bolts. But if its only 4mm thick, that doesnt give much thread depth, surely not enough to mount a transmission right?

Hi again
although the adaptor is 4mm thick this less crucial as long as the relationship between the flexplate and the torque converter . I spent a lot of time sorting out the conection of these two components to ensure that they maintain the right relationship .
second question
well that did happen and I" relieved" the bell housing in two places on that account but you can also use countersunk screws instesd of the bolts if needs be .
third question
this is a fair comment but in practice you are limited to a similar size transmission by the flywheel and or flexplate(and realy you will want to use the starter and flywheel from the motor if you can) because if you go much smaller you may not be able to fit an electric starter push starts every where , i don't think so . of the mountng bolts only a couple actually required tapping one ended up being located over a hollow in the casting of the block and I welded a nut on the inside of that one . and You dont have to be to hung up about getting a bolt in every hole as long as you have afair proportion all around it should work out OK .
Remember that the inportant thing is that you get the alignment right all of the other stuff will follow if you do .
best wishes
Iain

I was under the impression that some people fit a spacer inbetween the flywheel and block (same thickness as the new bellhousing/block spacerplate) so as to make up for the distance that they've been moved apart?

Guess this may not be necessary with a spacer as thin as 4mm but with some on the 1" ali ones I've seen maybe it's more important!

Cheers,
James

hi James
I can see where you are coming from but surely you must mean between the CRANK and the flywheel .
there is another way to mate a gearbox to a motor and that is to use the original bellhousing that matches the motor and adapt the gearbox at the rear of the bell housing an adaptor at this point may be easier .
best wishes
Iain

Yes, I do mean between flywheel and crank. Engine turns better that way!

I'll try and find the website I saw it on.

Cheers,
James

you can put a 1 inch spacer between the flywheel and the crank without any ill side effects?

i think i have found my answer, it looks like kennedy engineering uses a spacer, the same width as the adapter plate between the flywheel and their clutch assembly

look at the second setup discussed on this page http://www.lambolounge.com/Chassis/Transmission/5000/5000.asp