FJ40 3 Speed to 4 Speed Conversion with SBC (1 Viewer)

[SC Forester]

I haven’t seen this anywhere so I thought I’d start a new thread. I have a 1973 FJ40 that had a Chevy 350 mounted to a Toyota 3 speed via a plate adapter. The transmission and transfer case were dumping out fluid so I removed them with the intentions of replacing with a GM SM465. I couldn’t ever get the output shaft tapped and then ended up cracking the output shaft trying to remove a broken tap so that didn’t work out. I’m going to have my rig on the road a little more so I just got an H42 transmission out of a 1977 truck. I also just got a Downey bellhousing/adapter from a fellow mud member. I was looking at it and it looks like I can just move the pivot ball to the drivers side and try my current clutch setup. Has anybody ever used their slave cylinder on the drivers side with a Downey bellhousing. All of the threads I have seen show moving to the passenger side but that’s because they didn’t previously have a 3 speed setup. My slave cylinder is mounted to the frame and the rod pushed a GM clutch fork. Looks like the throwout bearing was GM too. I bought a low profile pressure plate for the SM465 project that I think would work with this. If my angles and distance of the push rod of the slave cylinder on the drivers side will line up, can I do it this way? I have no problem moving stuff to the passenger side but it just looks like it might work how it already is.

 

[SC Forester]

These pics are the Downey bellhousing. It’s made for the pivot ball to go either side just like the holes for the clutch fork. It looks like I could use the drivers side and bypass moving my slave cylinder.

 

[Pighead]

TLDR, slave cylinder doesn't care where it is

 

[SC Forester]

I took a look at how the slave cylinder was set up today and I’m going to be moving it to the passenger side. The previous owner went SBC to the 3 speed via a plate adapter. The way they set up the slave is to push a round bar that then pushes a welded on bracket and pushrod on that same bar to actuate the clutch fork. Does this look like a normal 3 speed clutch setup?

 

[SC Forester]

Couple more...

 

[SC Forester]

I replaced gaskets and the seals I could get to in my 1977 4 speed transmission and transfer case. Hooked the Downey bellhousing up, attached the new throwout bearing and hub to the clutch fork.
Next step is making my slave cylinder bracket to attach to the bellhousing. Getting a lot closer to finally putting in a transmission that isn’t the 3 speed!

 

[SC Forester]

Couple more pics...

 

[SC Forester]

Per @Downey instrux on an earlier thread, I have the throwout bearing clamped all the way back near the transmission so it won’t move while I position the new slave cylinder and bracket. I have the bracket as straight as I can get it pointing the slave pushrod at the clutch fork. I have the pushrod all the way in the cylinder in this position. Once I have the bracket mounted, I’ll unclamp the throwout bearing and let it move freely along the input shaft. Hopefully it will be in a good position in relation to the pressure plate.

 

[pb4ugo]

Back when when I ran a sbc and the stk 4 speed I was using the AA bellhousing, I think I 1st had the slave on the pass side, then yrs later I switched it to the drivers side. I don't recall why I switched, it may have been on a different 40. The AA B/H looks similar to yours, It mounted the slave on the b/h using 2 threaded bolt holes on the side. Idk, about downeys. Isnt mounting your slave side ways going to be difficult to bleed?

 

[SC Forester]

Back when when I ran a sbc and the stk 4 speed I was using the AA bellhousing, I think I 1st had the slave on the pass side, then yrs later I switched it to the drivers side. I don't recall why I switched, it may have been on a different 40. The AA B/H looks similar to yours, It mounted the slave on the b/h using 2 threaded bolt holes on the side. Idk, about downeys. Isnt mounting your slave side ways going to be difficult to bleed?

I didn’t take that into account...hmmm...That’s the way I had seen others mount their slave cylinder on the Downey bellhousing. Will it not work this way? I appreciate the feedback.

 

[pb4ugo]

If it works for others then go for it. Typically, the bleeder screw is oriented so its on top, so you can get all the air out of the cyldr. If its becomes an issue, it will be an easy fix.

 

[SC Forester]

Got it put in the truck today. Still have to set up the slave and move the clutch line. I hope everything will work.

 

[SC Forester]

Making progress (I think). I have the crossmember set up finally. I had to bolt everything up because welding would have been impossible with the body on the frame and plus I had to drill and move it around so it would fit correctly. I’ll probably go back and weld the three sides of the scab plates I can get to if everything works right.

Now my problem is driveshafts. The rear is too long and the front is too short. Also, the flanges do not match. Apparently the 3 speed driveshaft ends are nowhere near the bolt size or pattern on the 4 speed TC.

 

[SC Forester]

I have the 1973 front and rear end. There’s a good driveshaft shop nearby and I knew I would have to shorten the rear DS and lengthen the front DS. Is it possible to just change the ends of the driveshafts to where they will adapt to the new transfer case? I am running a complete 4 speed transmission with its 4 speed transfer case from a 1977 truck.

 

[SC Forester]

Yeah, I am looking at this on Specter off road page and it looks like I could just get the 4 speed yoke flanges and mate them to my 3 speed driveshafts. Then I’d just need the shop to lengthen and shorten them. That would work, right?

 

[SC Forester]

Ended up taking the originals that I took off to Carolina Driveline and getting them to shorten the rear and lengthen the front. They did an incredible job and they almost looked too good to put back on the Beast FJ.

 

[SC Forester]

Installed them today.

 

[SC Forester]

Getting so close to getting back on the road! The problem now is that the clutch is not working. The pedal goes straight to the floor. You can eventually pump it up but it’s not right. Maybe I can adjust the clutch pedal at the master cylinder and the pushrod on the slave cylinder to make that go away. We bled the $&@! out of it and there’s no air in the line. I’m also wondering if I didn’t mount or make the slave cylinder mount correctly. I 100% followed Downey’s directions on making it out of angle iron and where to mount it in relation to the pushrod in the slave cylinder. I don’t have a lot more room to adjust the nut on the pushrod and extend it further out. Most people have had issues where the pushrod was too long. This one looks like it may be too short or I made the angle iron mount wrong.

 

[pb4ugo]

When the slave is at rest, Is the piston bottomed out in the cylinder? Does your return spring still have tension on it at rest?

 

[SC Forester]

Yeah, I think the slave is completely bottomed out at rest. I made the bracket based on that. I had the throw out bearing pushed up to right at the pressure plate, then set the slave up so it would be at rest (bottomed out) in this position. I made the bracket based on this position.
The return spring definitely needs more tension though. That one may be too long.

When the slave is at rest, Is the piston bottomed out in the cylinder? Does your return spring still have tension on it at rest?