No it's not a Beach Boys song either. My 17 yr. old has been driving my 75 ford F-150 (302 / C4) back and forth to school about a mile away. I had to fill it up today and noticed a heavy vibration upon any kind of acceleration. If it coasts it's fine. So I assume it's a drive train issue. It really vibrates around 30 miles per hour.

It always has clunked when put into gear sometimes louder than others, but the tranny has never slipped and shifts fine.

Could this be the tranny ready to fall out or something more simple like a U-joint? and how would I tell?

thanks
GGuess

 

I'd say there's a 95% chance that's a U-joint. Put the truck in Neutral (block the wheels of course) and jiggle the driveline. If there is play at either end it's that u-joint. May as well replace them both if that's the case, as they are neither expensive nor difficult to do.

 

The "clunk" is a good clue....like it was said above, check the u-joints.

 

Thanks, I'll check the u-joints this weekend. It's been a while since I've changed any. Probably my old '63 Belair years ago. Usually I would drop the caps and have the needle bearings get lost. Onward to busted knuckles!

 

OK,

I blocked it, put the gearshift in neutral and crawled under the beast. The driveshaft has 3 u-joints in it. The drive shaft passes through a bearing or bushing of some sort between the front and middle joint. The front 2 joints appear tight, the back one has noticeable movement in it. Probably about 3/16 to 1/4"

Question is, what is the best way to tackle this. I'm sure the U-joints are not that expensive, it would be good to replace all three. Is the bushing / bearing going to be an issue or will it slide through it? Can I hammer in the new U-joints or is it better to have them pressed in?

The tranny looks like it was rebuilt at some point. It's not a greasy mess, but a nice clean aluminum case. I hope it's the u-joints and not the tranny.

Thanks much
G Guess

 

Question did you check driveshaft to rear axle how many plays?

My 79 F150 I blew up 2 diff member in axle due tow overload.


17 years old boy sound he did wheel burn that how it cause diff member in ford 9 crack. Where pinion's bearing housing is that what cause crack and cause huge sloppy in gear.

 

I'd suggest that you just drop the bearing in the middle as it's just 2 bolts usually and leave it attached to the driveline, rather than try to slide the driveline through. I had a '67 F250 with the same setup and that's how I did it. Unless the bearing looks to be really worn and also needs to be replaced there is no reason to remove it from the driveline.

As for the u-joints themselves, they are available for as little as $8 each. A press is preferable (and easier) for working with, but hammering them out and then in is acceptable also. Just remember to work one cap at a time and to keep the u-joint tight in the cap you're smacking as you do so, so that you don't lose any of the little bearings. Usually a socket that is the same size as the cap works well to beat on (or press if you go that route) in order to make sure that you're pushing it through straight.

Other than that, there really isn't much to it. You'll find that after you do the first one they'll get progressively easier to do, as you'll learn how to properly situate the driveline and u-joint while you're doing it. Only other things you need to be aware of are making sure that the clips that hold the u-joint caps in the driveline are seated all the way into their grooves (and not ****-eyed) and that the u-bolts' (on the transmission and pinion) little lips are seated properly.

The truck I have now used to eat u-joints on a regular basis (about 1 every 2 months) so I got to the point that I could do both u-joints on the side of the road or trail with a hammer, a socket and a block of wood (to hold it off the ground while you're smacking it) in less than 15 minutes. I've since solved that problem, thankfully, but it does get easy with repetition...

Good luck.

 

My 75 c-6 has a loud clunk, but it seems to only happen when shifting to reverse. Could this still be u-joints or does it sound like something else?

 

Shameless,

Thanks much, that's how I figured I would do it. The front u-join really has no stress on it since it's being held by the bushing. I'll replace the back two. Socket is a great idea, I'll put the bottom clip in before driving the joint in so it is seated correctly for the top. I'm hoping this is the issue.

Milwaukee,

I'm right down the road from you on 94 across the state line in the Gurnee, IL area. The rear end does appear to have some play. Only after putting in the U joint will I be able to tell if the rear end is broken up. I hope not, but I must admit, I like to spin some tires once and a while.

tlolesen,
Dunno about your clunk, I think transmissions and rear ends have a certain amount of slop, especially as they get older. On big thing to notice is vibration upon acceleration. It's like a bad wheel balance, only when you leave off the gas it disappears. I'm pretty sure it's the Ujoint. Crawl under your truck, put it in neutral (block it good) and see if the driveshaft has any play in the ujoints. Mine's pretty obvious.

Cheers to all
G Guess

 

Ok, I pulled the drive shaft tonight. The back U-joint had a lot of play. On the back joint, I popped out the retaining clips and the one cup looked fine. I pounded the joint out using a socket. The other side was void of anything that looked like a needle bearing and was bone dry - just a rusty void. The front joint was a challenge since it is held in by two clips and not being held by u-bolts. I pounded the joint to it's furthest position and it still would not clear nor release the bottom cup. I'm still thinking through how to put that one back together. I looked online and saw prices from $50 to $10. I'll opt for the $10. The carrier bearing wasn't that expensive either, about $20, may replace that too. Next step, onto the auto parts store. So far, no blood spilt.

G Guess

 

Well, since you found a bone dry cup with no needle bearings I'd say you're on the right track to solving your problem.

On the other joint, once you get the cap to protrude out one side you can usually grab it with an adjustable wrench (monkey wrench) and twist it the rest of the way out of there. Putting them in is usually a bit easier, since you've seen what you need to get it done.

 

How we know our diff member bad

here pic you see crack on pinion bearing housing that reason we feel heavy vibration and have HUGE sloppy I say almost like 2-3" play. Tired feel that jerk when you shift gear you feel bounce that mean driveshaft spin until hit pressure that make truck moving like jerk.

 

After destroying one of the U-joints trying to pound it in with a hammer, I took the rear section back to NAPA and had them press in the new ones. I also wanted to change the front carrier bearing - so I removed the front drive shaft section.

I didn't know that was was pressed in as well. I checked the front U-Joint and it was bad too. So in all I replaced all three U-joints and the carrier bearing. It works like a champ. No more clunking with shifting from forward to reverse - no more vibrations.

The bad side it I destroyed one of the bearings ($12) and broke my bench vise trying to press them in. So I went backwards on the deal. No blood, so in all a good day / about $110 including shop and parts (not including vise).