Hi,
I am new to the forum. I have a 1975 F250 4x4 with the 360. I am the second owner, bought about 20 years ago. The truck sits higher than other stock 75's. The previous owner said something about arched springs. Anyway, I am finding that all the parts do not seeme to be stock. I am replacing the U-Joints and thought the front are compound joints, as advertised, the real are also compound yet the auto parts books should symetrical. Anyway, can anyone tell me what a highboy is and how can you determine if you have one.

Thanks!
Bob

OK, I read elsewhere what a Highboy is. I think the sticky would have been a good idea. That being said, any help on the U-joint differences? Are the fornt and reak shaft supporse to use Compound U-Joints? which mine have and what about the Intermidiate shaft?

Thanks again!

 

Did you find the Read First: sticky at the top of the forum?

Are you asking if the highboy came stock with compound U-joints?

 

No, I read the READ FIRST sticky, after I posted..... Oops...

Actually I am asking two questions. First, are Compund U-Joints stock for the front and rear shafts? and second, where can I buy them? The local shops keep trying to sell me Symetrical U-Joints...

Thanks!

 

its a highboy....all f250's from like 69 to 78 are highboys...the only real difference in the highboy is the four inch blocks on the rear axle. and it has nothing to do with u-joints....the compound u-joints have to do with full time or part 4 wheel drive. if you dont have to get out and lock your hubs, then you have a full time four wheel drive and you will have compound u-joints with a yoke to connect them, otherwise on a truck where you have lock the hubs and pull the stick, then you will have assymetrical u-joints that are the same for the front and rear shaft(you will only have one at each end)

so to answer your question, yes it is a highboy....

 

Thank you for the information. Yeah, I have to get out in the mud to get out of it..... I apprecaite your help!

Bob

 

When you say "compound u-joints" do you mean a double carden, like the blue thing in the picture below? (ignore the green arrows) If that's what you are talking about they're not unique to just rigs with a full time 4wd. They were used in a lot of applications that had steeper angles at the joint, especially the front driveshaft in later model 4x4's with a married t-case. The unit just consists of 2 regular u-joints, nothing more. If you pull them out they can be replaced easily.

If this is not what you're talking about than ignore my blabber . . . that's all I could think of when you mentioned "comound" joints.

 

Yep,
That is what I was talking about. I think the bottom line is that I need to find another parts store that can get me the right part. The U-joints I need are Asymetrical in design, yet they keep trying to sell me Symetrical Joints. I found that the parts store has the right joints for the front, which should be the same for the rear, but they tell me it is not so. So I am going to buy to set of front shaft Asymetrical U-Joints.

My point in asking the questions was tomake sure that the previous owner did not make a change to the OEM design.....

Thank you for your help!
Bob

 

Bob, I would not even tell the parts store what kind of truck they're going into. Pop the u-joints out of that double carden assembly and just take them in. Napa or any of your better shops will measure the caps and the cross section and get replacements. That will save any confusion about whether they've got the right ones.

I may be wrong here but I didn't think the "highboys" had a double carden in them. The front driveshaft should be as long or longer than the rear meaning you won't have any extreme angles requiring them. The DC will split the angle between 2 u-joints meaning less stress and binding on them. I'd say there's a good chance that it was swapped in. This isn't a bad thing . . . I just don't think that's how it came stock which, if correct, would explain why you're having trouble getting parts stores to find it in their books.

Trivial info: A double carden joint is also referred to as a CV joint, though it's not at all the same as a CV joint in a FWD car.

EDIT One last thought. I believe normal U-joints are asymetrical meaning that they fluctuate in speed as they turn. There's a whole big long explanation to this which I don't fully comprehend but I think they would not be symetrical. Double cardens use 2 joints which basically cancel eash other out in terms of the speed fluctuation. Therefore I'm wondering if this is what they mean by a "symetrical" joint. Don't know if that makes any sense but it might be something to look into. I've never really heard of them referred to in that manner so I don't know.

 

Thanks again, Good advice on the U-Joints. One of the better places I called today said they would do just that, measure the caps and cross section. I am getting confused on the types of U-joints and it is hurting my head.... Better to just take them in ans tell them to get me ones just like it!!!!

This has been a great help, glad I found you guys!

bob

 

I saw a "highboy" from '74 with the "CV" u-joints (doubles), but that was because it was a FULL TIME 4x4! Front hubs didn't have manual locks, just axle flanges, and the transfer case had 4x4low and 4x4 high.

Yours may have been one of those that were converted. Or, it wouldn't be the first time Ford stuck something in a truck that wasn't supposed to be there. My '74 was a part-time 4x4, so it had the locking hubs and four-position transfer case, and had normal single u-joints.

By the way, to the guy who said the highboy is nothing more than 4" blocks in the rear, my '74 highboy (F250) had the rear chassis width of an F350. It looked basically like an F350 chassis with F250 running gear on it (and an NP205). The front was way higher than standard F250 4x4's too, so in my mind, the highboy F250 is an F350 chassis with F250 running gear.