Vibration at 60-65mph; also U-joint oddity...ideas??

[dozer]

I've got a low-freq vibration in the 91 5spd 4x4, between 60-65. It's still there with the clutch in, and with the tranny in neutral.

Here are a few things that -might- be related...

On the way home from buying it, a month ago, I noticed that when it would go torque-neutral, i.e. the grade was such that it was just floating between accel and decel, it would "kick" now and then. I could see the shifter twitch...and the higher the speed, the harder it kicked. At 70, it felt like the truck itself was getting kicked. Kinda worrisome.

A couple weeks later, we had to use the truck to pull a trailer for hauling a car home. On that drive, it started making a little screechy noise under load. Kinda like an angle-grinder on sheet-metal...

Mikes sez "it's a U-joint", so I went and picked up a pair for the rear shaft.

I was driving it over to Mike's place to change 'em out, and noticed a vibration/shudder when I first got onto the freeway. Not horrible, but could definitely feel it.

When we pulled the driveshaft, the joint at the T-case had broken needles in one cup, and a pile o' dust in the other... In fact, the end-piece that slides into the t-case looks discolored over the few inches nearest the u-joint.

When installing the new U-joint at the rear end of the shaft, we could not get the C-clips to go in easily. By really wailing on it, we did get the clips in, but the joint wouldn't rotate freely on that arm. Didn't like that at all, so we pressed the joint back out, and checked the new and old joints with a caliper. The new one was .045" longer than the old.

Hard to believe they make 2 joints so close in size....but this one didn't look "mis-made" either. Nor could I see how the yoke could be bent. It's got a lot of metal in that area....and no signs of impact or other damage.

We ended up hitting the ends of the cups with the grinder...taking .025 off that little 'ridge' on each cup that runs around the outside edge. Reinstalled it in the yoke, and it felt good.

Anyway, I thought all my driveline problems would be solved, and the screech is, and I think the 'kick' is too; but the vibration/shudder is NOT.

If it's not the rear-shaft, and not the tranny (tried it in neutral, vibe still there), what the heck is it?

Didn't Zigg once have a hard-to-find vibe that turned out to be the T-case?

Mine has dried out goo over a lot of it...so maybe something went wrong there. I've heard of the pump coming loose inside....that sounds like the kind of thing that might throw fluid out of the breather hole!

But the fluid level is OK, and it's ATF. T-case seems to work fine.

One final 'symptom'... I've noticed at some speeds and/or pedal-settings, I'm hearing sort of a 'hiss'. If I press the T-case shifter forward a bit, that hiss (I -think- it's the same noise) gets more pronounced, and a little harsher sounding. If I pull back on the lever just a bit, the noise seems to stop.

I don't remember my '86 ever making a noise like that...

So, am I looking at a new T-case? Or is the vibration/shudder something else?

I also have DMF/clutch issues, but this shudder is always at 60-65 mph, even in neutral and/or with the clutch in and engine at idle.

Richard

 

[Roland_Jenkins]

Slip yoke could be worn, grease it. You may need a needle nose grease gun adapter thingie. If you take the slip yoke apart to grease it, be sure and mark the alignment with lumber crayon.

Carrier bearing going bad if so equipped.

Drive line angle.

Probably not this but it could be a tooth broke off of the ring gear throwing it out of balance. Had that happen on a truck before.

 

[dozer]

Slip yoke could be worn, grease it. You may need a needle nose grease gun adapter thingie. If you take the slip yoke apart to grease it, be sure and mark the alignment with lumber crayon.

Carrier bearing going bad if so equipped.

Drive line angle.

Probably not this but it could be a tooth broke off of the ring gear throwing it out of balance. Had that happen on a truck before.

argghh....don't even -think- expensive thoughts like that Roland!

It's a 4x4....so no carrier-bearing. When you say slip-yoke, I guess in this case that'd be the part that slides into the back of the T-case, eh? I guess I could pull it back out and grease the splines... Probably a good idea anyway, although I don't see that fixing the root -cause- of the vibe...

Edit; just re-read your thoughts...and see that you mention yoke being worn. Quite possible I guess...195K on the truck.

So you're thinking that the grease might at least -affect- the vibe, letting me know that the yoke is bad?? I could try that easily enough. Just 4 bolts to drop the shaft again. So what's the fix? Replace the yoke? Or would the shaft in the t-case be worn as well?


Drive-line angles should be stock. No lift or other mods as far as I know. Were vibes a problem with these trucks even stock? My '86 F350 is identical configuration cab/bed/driveline and never shook at all. I guess one difference is that it was a T19 instead of a ZF5.

I guess we could pull the cover and look over that ring-gear...but I hate to even go there...

Richard

 

[LUCKY_LARUE60]

I had and still do at around 60mph. It is in my brakes, first thought it was in the rear, replaced everything, shoes, springs everything still there. I now know it is in the front brakes, as I can feel it in the pedel when I apply slight pressure to the brakes. So look at brakes, just my thoughts.......... Jim

 

[zigg]

Didn't Zigg once have a hard-to-find vibe that turned out to be the T-case?

Sorry Richard. I did have a hard to find Vibe, and it's been 2 years now, and I still haven't found it. I've replaced everything on the truck except the engine, and that's about to be replaced in the next few months, so here's hoping....

I did rebuild my T-case though, and learned a lot, but didn't find anything that would cause the "vib"

Zigg

 

[Agnem]

We ended up hitting the ends of the cups with the grinder...taking .025 off that little 'ridge' on each cup that runs around the outside edge. Reinstalled it in the yoke, and it felt good.

:***:

Excuse me, but that definitely is not right, and I certainly would not have used that U-joint. Sounds to me like you either have the wrong part, or one of the needles fell over inside the cup, and you've tried to crush it in there.

 

[dozer]

:***:

Excuse me, but that definitely is not right, and I certainly would not have used that U-joint. Sounds to me like you either have the wrong part, or one of the needles fell over inside the cup, and you've tried to crush it in there.

yah, that's not right...

howdy Mel...sorry for delay in replying...we've been on the road for a while.

Nope, no roller on its side. We checked for that several times.

We also checked 3 ways from Sunday, and the books said this U-joint was the right one. Also, it is only a few thou different from the old one. It didnt' make sense to me that they'd have 2 that were SO freaking close...

I dunno what to think tho....perhaps the yoke is bent, but it sure doesn't look it. Plus, if it were bent, you'd think it would also be -angled- and the U-joint wouldn't go in right. But it tapped into place pretty normally.

Anyway, the vibe was there before the joint change, and is just the same afterwards. So at this point, I'm operating under the assumption that the u-joint is not the vibe-cause; even if it IS a little whacky...

So I'm wondering who else has had a vibe around 60-65, and what did you discover was causing it ?

Richard

 

[Agnem]

One thought is this. When I had the driveshaft made for the Lady Moose recently, I brought it in without U-joints. I told them I wanted it balanced, and the guy said "bring in the U-joints your going to use. We need them to balance it. I said "oh." and had them sell me some on the spot to save time. If they think the U-joints are that important to the balancing, maybe going to the Ford dealer and getting a new pair may be worth the agrivation.

 

[PackRat]

Here's a thought from the KISS (Keep it simple stupid) theory.

Most tire/wheel vibration hits peak harmonics at 30, and 60 mph. Just for a cheap check, I'd pull the wheels, check for mud inside, and have them re-balanced.

The previous owner of the 62 C-20 I have, thought the tranny was going out, due to a vibration through the shifter. After swapping in a higher geared pumpkin(no relation to the vibration issue), the vibration was gone. Seems it was traveling up through the driveline, and showing itself through the shifter.

Just another $.02

 

[Dalvaras]

yah, that's not right...

howdy Mel...sorry for delay in replying...we've been on the road for a while.

Nope, no roller on its side. We checked for that several times.

We also checked 3 ways from Sunday, and the books said this U-joint was the right one. Also, it is only a few thou different from the old one. It didnt' make sense to me that they'd have 2 that were SO freaking close...

I dunno what to think tho....perhaps the yoke is bent, but it sure doesn't look it. Plus, if it were bent, you'd think it would also be -angled- and the U-joint wouldn't go in right. But it tapped into place pretty normally.

Anyway, the vibe was there before the joint change, and is just the same afterwards. So at this point, I'm operating under the assumption that the u-joint is not the vibe-cause; even if it IS a little whacky...

So I'm wondering who else has had a vibe around 60-65, and what did you discover was causing it ?

Richard

Well I would not be too sure about the sizes being so close being an odd thing it ttok me three trips to get the right U- joints for my truck last year well actually 2 the first was my wife stopping to get parts on her way out of town to pick me up after I dropped the drive shaft while backing over the curb at the job site. Parts store insisted that my 1991 had a two piece shaft when I told her on the phone that it was not.
Then when I went in there they had to do some searching to come up with a listing for the 1 piece shaft then those caps were about .035 of an inch too large to fit my shaft. finnally had to go to old school and look in the paper book back in the corner of the store being used to prop open the back door to find the actual part that I needed. And beforer I bounced the shaft out on the curb I did have a vibe at 45 - 55 MPH

 

[dozer]

hey guys, appreciate the replies, very much.

Dalvaras, yeah, they had 3 different setups shown in the book, for the -same- model/year truck. The first time round, they sold me joints which weren't even close; i.e. 1-1/8 dia caps instead of 1-3/16, and the cross was too small by 1/2", etc..

So you say you DID find two different part numbers which were different only in the length across ? By .035" ?? It wasn't clear whether you meant diameter or length of the cross. My 'fit' issue was the length...

If so, then yup, they gave me the wrong part...AGAIN...

My vibe is in the 55-65 range....perhaps a gearing diff? I have 4.11's, and a posi in the rear. Jesus....I hope Roland isn't right... He suggested a broken tooth in there...yikes...

 

[Dalvaras]

THe ones I ended up getting were .035 smaller in diameter the cross was the same

 

[rancherman84]

what about a bent rim?
i run 33's in the summer and 285r16's in the winter,i get a vibration in my truck at 55-60 in the winter only from my bent rim.

 

[Dsl_Dog_Treat]

Got the same thing and speed range going on with Goldie, but also have a u-joint going out on the rear driveshaft behind the carrier bearing that was just replaced. Could be splined shaft that I'm gonna be looking at a little closer next, as was not packed very good with grease when I bought it and might be getting some not so noticeable wear on it.

Just a thought?

Ron

 

[dozer]

Dalvaras, mine were the perfect diameter....just that the cross was about .040 too wide. It -would- go in, but then the U-joint was very tight, wouldn't turn on that axis.

Rancherman, thanks for the thought. I hadn't thought about rims....I guess because the vibe seems to be at the higher 'frequency' that usually comes from driveline, i.e. "grrrrr" instead of "thumpathumpathumpa" like a tire :roflmao:

But heck, I might be judging it wrong. I'll check the rims/tires out.

Ron, yeah, someone mentioned early on that it might be the spline going into the t-case. Hope not, but heck, that's better than it being a broken tooth in the rear-end!

Richard