68 drivetrain help

[sco68fj40]

Hello, I have a 68 fj40 with stock drivetrain. Eventually I would like to run 35" tires and thought that the drivetrain would need to be upgraded for the added stress. Are there no options for this model year for chromoly axels or lockers? I thought I had 30 spline axels, what do I have to work with here? Also, a little insight on what my birfeild's strength would be nice... differences from later years, if any.

Thank you for your help

 

[sco68fj40]

Okay, so I found the differences in the FAQ section, 68-75 birfields have 10 spline outers versus the 30 spline of later years, the stub axels are 168mm versus 188mm of later years, and the flats have a distance of 83.5 versus 84.5 of later years. The outer diameters are the same at 90.5mm. I do have a worn hub though, so does this mean I could have this changed? 68 and later years have 30 spline axels.

My questions still remain on what options I have for after market upgrades on chromoly axles and lockers. And will my stock running gear hold up to trails with some rock crawling involved on 35's? I understand the stock running gear is stout, but 10 spline outers don't sound comforting to me. Any advice would be greatly appreciated.

 

[Josie'sLandCruiser]

Hi All:
Honestly, the only way to be sure what you have is to pull your junk apart . . .

The rear axle is relatively easy - just drain the gear oil, pull the rear diff cover, then count the splines on the axle shafts.

The front axle will require you to dis-assembly at least one hub. If you pull the CV joint (aka "Birfield") and inner axle shaft you can then count the splines at the hub end and at the differential end. Even if you have 30 spline axles at the diff if there are coarse-splines at the hub you need to upgrade (or, pack spares! )

Regards,

Alan

 

[68LC]

Sco68 -
Don't be in such a hurry to modify your LC, the're pretty bullet proof the way the leave the factory. I've driven stock suspended, open differentialed skinny-tired fj40's (the hubcaps are a nice touch) for the past 25 years, and have gotten everywhere I need to. In the 400,000 or so miles I've driven these things, it has been my experience that if maintained, the differentials need work every 120,000 miles or so, and its not the ring and pinion, its typically the spider gears that flake out. Never had a problem beyond maintenance with bearings, seals, hubs, axles, CV's etc. You have to keep up on these things. I'm a geologist by profession, I've used the LC's on and off road all over the southwestern USA, most days driving off-road to make a living. My advice, keep it stock, use your head, keep it maintained and enjoy it. My current FJ is also a 68, Picked it up 2 years ago with only 80k original miles - I dig the column shift. Remember - It aint whatcha got, its how you use it. Have fun!
Best regards;
Greg

 

[shelfboy1]

it depends on your wheeling needs my son ran a 65 40 when he was 14 for mud and trails with 35s and never had a problem .rock crawling is a whole new ball game for mild wheeling and street use you may be fine good luck