Gearbox adapter plate minimum thickness for threaded holes

[oldcorollas]

seems far easier to do the bar trick, rotate BH to whatever angle you want, and then weld in place

[JustenGT8]

Any option is gonna give you some issues.

BH>adaptor>box is probably the best idea and the smallest, best located and strongest adaptor. May give spigot bearing issues? Just requires decent machining.

engine>adaptor>BH has been done a million times so like the option above it's just decent machining that's required.

Cut and shut BH will cause you headaches with the clutch fork alignment which could get ugly to rectify? Could go hydraulic release bearing but from what i have seen these are a PITA to set up.

Tilting the engine doesn't look great cosmetically (and means your current sump is scrap) but may have advantages in being able to get the engine lower as the sump pan will be offset? Doubt i'd go that way myself but i just threw it out there in the mix.

[TurboRA28]

Regarding the alignment after a cut n shut, if I make a jig that ensures input shaft and crank alignment location don't change then I should be pretty safe eh? Not sure how that'd change clutch fork alignment?

[hemi twofifteen turbo]

It's not possible to drill the new pattern straight onto the original bell housing? Would have no thickness problems that way and avoid all spigot/clutch issues. Never seen the type of box your running so not sure if it runs any type of 'hub' or complex locating shape but even if it does I see it as no more work than making an adapter plate but with a better result?

[AdrianS]

Re countersinking - what I did, and assume the OP is planning, is to use countersunk head cap screws. They are self-centering, and sit flush in the countersunk hole.

[JustenGT8]

Regarding the alignment after a cut n shut, if I make a jig that ensures input shaft and crank alignment location don't change then I should be pretty safe eh? Not sure how that'd change clutch fork alignment?

You are rotating the clutch fork respective to the slave cylinder mount. Given how much force goes thru this any bracket to relocate the slave cyl will need to be very beefy and accurately aligned.

[TurboRA28]

Maybe I can make the cut infront of the clutch fork/slave cyl section.. more in the middle of the bellhousing. The shape is a lot more symmetrical here as well.

[allencr]

Regarding the alignment after a cut n shut, if I make a jig that ensures input shaft and crank alignment

Don't align on just the input shaft. From the front & rear main bearing saddles thru the trans case's front bearing housing, the mainshaft's bearing and then the tailshaft/extension housing bearing. It needs to be straight all the way through and there is too much play in the input/first motion shaft & bearing, and that tube the release bearing slides on that surrounds most input shafts probably isn't close to straight.

[gixer]

This is the adaptor I made up to bolt an MX5 6 speed gearbox to a 4AGE(this is only pic I have out of car and when this pic was taken the plate was not finished) All the critical machining was done on an NC mill to ensure accuracy. It is dowelled to the 4AGE as per normal, then the MX5 gearbox is dowelled to the adaptor plate. The plate has been on the car for a few years now.

[Cuzzo]

How much did that plate cost you gixer?

[TurboRA28]

So there is really no way to do it without having a bare block?

[CrUZida]

Obtain a copy of v-eight.com's W58 to auto bellhousing CAD file
Obtain a 3VZ-FE autobellhousing from Prado
Modify CAD file to rotate auto bellhousing bolts desired amount
Get adaptor made
...
Profit ?

[gixer]

How much did that plate cost you gixer?

I made it myself so just cost of material, I'm trying to remember what I paid for ally plate, but too long ago. I'm an amateur so took a while on the mill, usual story measure twice machine once. Has been in for years and no problems. I wanted to do it as easy as possible.

[lexsmaz]

I would think as has been mentioned a 10 to 12 mm plate would be required & obviously you will measure things up, but i would think you might run out of length to engage the input shaft into the spigot bearing ? & you would need to make up a longer pivot bolt for the clutch fork & again you could have issues with the throw out bearing actually running off the very tip of the end of the throw out bearing support & cocking over & jaming ?

The other thought i had is there enough material surrounding the bolt holes that go through the Bell housing into the gearbox & could the holes be elongated or re-drilled in the Bell housing & then re-welded & machined once you have established a good upright position for the gearbox, pressuming you can actually rotate the box slightly ? ....

Rob ..

[hemi twofifteen turbo]

yeah second the redrill option, wrote it a few posts ago and no direct response.. maybe missing something obvious that make it unfeasible?