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I have a 1976 F-250 "highboy" with an 8" lift (I bought it this way) it currently has 37"s on it and with the amount of lift the tires still look small. I'd like to upgrade to 42x14.5R17's but I'm not sure the axles will take that much rubber. I don't do any serious off roading and I don't really use the 4x4. The front diff angle is way off, it practically points to the ground instead of the t-case. It has a dana 60 in the rear and a 44 in the front, everything I've read about the 44 is from jeep guys who do comparatively crazy stuff off road. It has a 390 that was rebuilt and bored .20 over, a T-18 and an np205. From what I've read everything apart from the axles is bulletproof. I would like to upgrade to a 60 in the front before I really take it off road but for now I'd just like to know if I'm not too rough with it, will it take the bigger tires and not blow my diff up? Thanks in advance!
I would look at getting some pinion angle shims for the front axle. Since it is a High Boy, you have a low pinion dana 44 front axle and I am sure with 8" lift and no shims, that pinion angle is bad looking.
If you do not wheel it hard, really use the 4x4, and stay off the skinny pedal doing burnouts, you should be fine with the 42" tires. Shop careful for those 17" rims. The wrong back spacing/offset can get them in contact with your front tie rod ends. Front drum brakes right?
Instead of the D60 front axle upgrade ($$$$ to even find one these days) just research if their are some upgraded axles (chromoly) available. Are you breaks in good working order? That is ALOT of rubber.
I would look at getting some pinion angle shims for the front axle. Since it is a High Boy, you have a low pinion dana 44 front axle and I am sure with 8" lift and no shims, that pinion angle is bad looking.
If you do not wheel it hard, really use the 4x4, and stay off the skinny pedal doing burnouts, you should be fine with the 42" tires. Shop careful for those 17" rims. The wrong back spacing/offset can get them in contact with your front tie rod ends. Front drum brakes right?
Instead of the D60 front axle upgrade ($$$$ to even find one these days) just research if their are some upgraded axles (chromoly) available. Are you breaks in good working order? That is ALOT of rubber.
Thanks for the info, it has disks on the front and yes, The front pinion angle is awful. The front driveshaft isn't actually in the truck right now as I don't really want to replace U-joints twice a week 😂
I've never had an issue stopping the 37"s and I've had to put enough force in the pedal it's locked them up before, I'm planning on going through and servicing all the brakes and both differentials soon, just to really be sure everything is in good working order.
Yes you will need to figure out the correct * shims you need. Yes you will need to u-bolt the leaf springs from the axle and use the leaf spring center pin to hold them in. That means un-clamping the leaf spring. WAY better done with the leaf spring completely off and in a vise. Using C clamps with the leaf springs still on the truck a PITA. And I highly suggest that you do not just loosen the u bolts and hammer in the slotted style ones.
I know how to measure the angle I need to get the correct shims. The main issue I think I'm going to have is because it's so tall I'm not sure the best way to jack it up to remove the u-bolts. Would it be possible to lift the truck off the front axle and place the shims or would that be more trouble than it's worth?
it's not the prettiest one out there but it's mine and it's sure fun
Yes either lift the complete front end up (fork lift, skid steer w/forks), whatever direction you go (truck frame up, suspension down) you have to have the front suspension (leaf springs) fully unloaded, meaning the front suspension at full droop. NO truck weight on them. Pull the calipers, shocks, sway bar if installed, disconnect the pitman arm. You will have to have it on a full vehicle lift or jack and jack stand it at the frame rails behind the leaf spring rear shackles. To be able to loosen the u bolts, and drop the axle enough to be able to get to the leaf spring center pin, to be able to pin the shims in place. It is almost like putting a complete new front lift kit on. Remember you can remove the wheels and tires to get the front axle lower. Yes that is 5 jack stands. 2 primary load, 2 back up and a 3rd center back up. Safety 1st, great way to get hurt doing it wrong.
OK excellent, thank you for all your advice I was really racking my brain trying to figure out the best way to take care of that front pinion angle. Even with the wheels and tires off the frame is still way high and I don't have access to a 4 point lift. Guess I'll get some 10 ton Jack stands. Everyone already complains that it's too difficult to get into with the 37"s, I'm gonna laugh when they try it with the 42"s.
Well just jack it up and support it VERY secure. Not a cement block sort of deal, that is how people get hurt and or killed. Do you have "rent a shop" business in your area? Like a DIY garage where you can rent a work spot with a lift? Have you considered trying to source a 78/79 Dana 44 (high pinion) and change it over to the 78/79 style steering? That would help with the pinion angle issue a lot. I cringe when I look at this picture.
Yes I agree safety above all else. I honestly hadn't ever even heard of a shop like that, sounds like a good idea. I've had various ideas for the front axle. I even considered swapping dunce and a half axles into it and there's even a specialty shop near me that does just that. But I like the idea of being able to drive it on the road still and with the 6:?:1 final gear on those axles it wouldn't go anywhere fast. But it would go anywhere.
You talking about Boyce? Well you said "I don't do any serious off roading and I don't really use the 4x4", so why bother, if it's just for looks? Sorry if certain statements or questions are blunt. Your money, your time go for it. Just post a pic.
Boyce Equipment & Parts Co., Inc.
2893 S. American Way
Ogden, Utah 84401
It's not necessarily a mall crawler or pavement princess, I still use it offroad for light duty I just haven't really needed the 4 wheel drive where I've gone. And it's still a work in progress, I didn't use it much last year because there was an electrical gremlin I was chasing down. Got that sorted and it runs fine now just not the 4x4. Which thanks to you I have a plan of how to fix. This is how she sits currently.
Yes that thing is a big beast, with a lot of lift. What size are those rims? 16", 17", 18"? I would say some 40"s would fill the fenderwell just fine, 42" are getting way up there.
It's sitting on 37x13.50R20's right now and I'm really not a fan, I've always liked alot more rubber. I like the older style mags personally and that's what I'm going to switch to when I get the bigger tires.
To bad the older style slotted mags are 16.5, but at least you can order big tires for big rims now days. Way back in the day you had either 15's for a 1/2 ton and 16.5 for a F250 ONLY.
I dig some old school steel white spokes, red blue pin stripe and chrome cap and lug nuts.
https://www.jegs.com/i/MHT/608/U1011...SABEgIiKfD_BwE
I'm not 100% certain on the backspacing but I just found these while browsing. They're a 17x10 with the correct lug pattern and they look like just what I want.
