fj/hj 47 front driveshaft

Putting the transfer case from the 4Runner in the FJ40 has caused all sorts of issues. I knew this would be the case since the stock FJ40 is passenger side differential and the 4Runner/Tacoma is driver’s side differential. I solved that issue by cutting the front axle pumpkin off, notching the housing for the 3rd member flipping the drain plug from bottom to top; which became the bottom when I flipped the axle, and cutting and flipping the end knuckles. Again this axle issue was solved a long time ago. But that still doesn’t connect everything to provide 4wd. 

The front driveshaft needed to have a carrier bearing to work with the leaf spring from axle since the driveline would be flexing. Yesterday I decided to tackle this project. I used a two piece rear Tacoma driveshaft and cut it up to make all the pieces I would need. I’ve gotten half way decent at making new custom length driveshafts. Luckily these are smaller sections, so I can true them and set them up for welding on my 13” South Bend lathe. Using the rear driveshaft for my front driveshaft allowed me to have larger u-joints for strength but it then caused an issue with the small bolt pattern on the pinion flange from the stock FJ40 axle. 

My neighbor assisted me on this and made a plate that I could drop the stock flange into and weld. Then I recut the larger profile of the plate and drilled holes to match the new custom driveshaft flange. I could have left the pinion flange alone and used a conversion u-joint but I thought keeping all the same u-joints was a better move. I made a mount for the carrier bearing that comes off of the transmission crossmember. It all turned out well. 

I now know that my front section of driveshaft is the correct length (after my initial guess) and now I can fully weld this. One step closer…

 

ural drivshaft repair

I few weeks ago, I had a sticky rear brake so I was inspecting things when I noticed some serious wear in the Ural driveshaft. The u-joint had disintegrated due to lack of grease (there was no grease zerk as there are on later models). I assume this had never been looked at by any of the previous owners and I had obviously neglected it and riding all winter probably didn't help the situation. The driveshaft yoke was ground down from the wear so I figured a new driveshaft was the solution. I thought fitting the newer style removable yoke sections from a late model Ural would be the way to go, but it would require dropping the swingarm, and with seals, shims and such, I was looking at over $250 in parts alone. It happened that as I was shopping, I found someone (on the soviet steeds black market) who had an early style driveshaft, u-joint, end drive fork, and shims for $20 that appeared to be brand new. Two days later I had the drive shaft in hand. When I tore into the rear-end, I discovered some metal pieces inside the brake and drive spline area. I panicked at first thinking it was the drive splines, but discovered the brake shoe pivot had slid out of it's casting boss and was grinding on the inside of the wheel hub. After a thorough cleaning I had the pivot reseated and everything re-greased. The new driveshaft is a fine spline shaft, but I don't think that will be a problem. I assume that Ural made the switch from course to fine splines at some point. Since I had the replacement drive fork that matched the driveshaft this was no problem. I made sure things were properly lined up and shimmed when I installed the new shaft.  If the square pin in the shaft is not properly located then you can crack the pinion (see this article). Also Gobuim shows the correct yoke alignment here (for future reference). Maya came out and helped and even took a few pics while my hands were dirty. Even though I was dreading this, it ended up being a fairly easy repair. The new u-joint has a grease zerk so I will be sure to maintain this so I don't have to do it again for a while. I'm bag riding the Ural and everything seems to be good. I did swap the rear wheel with my spare as the knobby tire had worn a bit during this last stretch of riding. I'll try to keep these in regular rotation to make them last.