Of course,,,I'm out on the road again.

I've had a slight shudder on take off for a while. About 6 month's ago, I changed all the u-joint's, and carrier bearing. It got a little better, but not cured. Figured I needed the spacer under the carrier bearing, but never did it.

Now I'm down in Florida with my 3 car trailer. When I take off, the whole truck shake's really bad. It's getting worse and worse. I dropped the trailer and it barely does it on take off. I checked the u-joint's, they're all tight. I am getting a bad clunk at the rear joint, but I can't tell if it's the joint or the rear end.

The only thing that has been done lately is changing the valve body a couple of month's ago. Trani seem's fine. Could it be coming from there.

Also, I didn't use any friction modifier last time I changed the gear lube in the rear, but that's been almost a year ago. You guy's think I could get lucky and add some,,,or am I looking at something major.

I'm really open for suggestion's. Anyone live in Florida. Thank's.

 

friction modifier not required with the AM axle.

Can you "drive through" this shudder? I've found in maybe three occasions where customers have the right load, right grade, right pin weight, and experience spring wind up. Cure in all three instances have been air bags. On two of these trucks we shimmed driveline and rear pinion angle. Anything I did that would greatly improve the launch shudder, would pop up higher in the rpm scale (launch would subside, but often a 45-55-65 mph drone would occur). The front spring segment is much longer on the DR trucks than the previous BR/BE body. That and a little lower stall seems to aggrivate the problem too.

 

Yes I can drive through it. It only does the bad shudder on take off. I believe it's more serious than what you're thinking though.

When I come to a stop, and it downshift's to first, it feel's like the trani is falling out. Sometime's it sound's like it's coming from the front, and sometime's the back. It really sound's like a u-joint slapping. But they're all tight. I think I will change the rear one just to eliminate it. Could a u-joint cause a shudder like that.

 

Man BRJ your hard on stuff. Could it be that you broke a gear in the tranny or possilbe convert is slipping on take off?

 

I just read about this in TDR mag. It's a third gen shudder that requires some kind of spacer to be installed between the axle and springs to change the driveline angle. There is a TSB on it. Sorry, I don't have the mag handy as I am at work. A Search on TDR found this, which might be it: TSB 03-003-04 Launch shudder


Chris

 

It was the center u-joint. Lesson learned,,,check u-joint's while the truck is in nutrel so there is no bind on the drive line making you THINK everything is tight.

Thank's for all the help.

 

I just developed a squeking at low speeds last week. Now I've gor a vibration on accel or maintain that starts about 50 and get worse the faster you go. It nearly goes away completely when I let off the gas on the highway. I believe I've got a bad ujoint somewhere, I think the rear. How can I test them? How hard are they to fix DIY style? Must have been this rash of IL snow / salt we've had this year.

 

Check for slop while there is no pressure on the driveshaft, meaning don't let it roll into park. Put the parking brake on while in gear. Also check for noise when going from gear to gear. If your's are the original's,,,,they probly need replaced. Everyone say's use the Napa greasable one's. I'm on my second one within about 6 or 8 month's. Not really saying they're no good, especially since I never greased them, but next time I'm going to try something else. The Napa's are from across the water just like the rest.

You either have to beat them in and out with a hammer and socket,, or take them to a shop with a press that know's how to do it. I guess it just depend's on how much you want to spend.

 

Well I should have measured before I took them apart. I got the rear driveshaft out, beat out the back joint, and then noticed how much larger the 351A is that mine that came out. HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH. There must be a difference in ujoints, probably has something to do with auto vs. 6 speed.

So now I'm stuck at home until my wife or step daughter come home. I'm also going to start searching for the right part number for my truck . . . .

 

Ok then. I did both rear joints. The front wasn't bad, yet, but I did it anyway while I had the shaft down. The rear, well now. That's a different story. One of the caps was actually rusting away, and there was not a shred of grease or bearing it it at all. The oposit end had eaten the bearings down to about 1/2 their correct length. I did manage to put the front joint in 180 from how I took it apart, and also put the rear union together 1/4 turn off. I had a little vibration, so I took it back out and flipped the front joint and re-aligned the rear bolt union so it all fit back together right. The front was just a miss on my part, but the rear I'm blaming on the 25 F temps with strong winds and blowing snow. My fingers were cold and I just wanted to get it back up quick. Now I'm back to normal again, with better knowledge of how to tackle this in the future. Of course, having the right joints would have helped too. I had the same problem, not checking the joints in neutral with no load. Once I took the preload off the shaft, it was obvious with one was bad. I'm going to make a post wiht the right part numbers. 295 Precisions, with the zerk in one of the caps. That's what the autos take, the 6-speeds are the 351A.

 

Where did you get the u-joint's. O' Reily's maybe?? The Napa # is 338. At least that's what they sold me.

When you greased them, did grease come out of all the cap's. When I did mine, it would only come out of 1 cap. This make's me wonder did all the cap's get greased. The fitting was in the middle of the joint.

Did switching the shaft around get rid of the vibration. I now have a vibration that I never had. I'm 99% sure I put it back in the same. Maybe not though.

 

Was your's a Napa part? This one is one boxed in a Precision box, with 295 on it. It says 'Made in the USA' on it too. I believe this is their 'heavy duty' version. It's got the grease fitting on the end of one of the caps, rather than the center. I've never seen one like it before. I got grease out of two or three of one joint, and all four of the other. It's got metal mounting surfaces inside the caps, and on the main body as well. So there are four little grooves to allow the grease to get from the paths of the main body to the bearings.

Flipping the front yoke over, and putting the rear mating plate back together the way I found did fix the vibration. It wasn't bad, but it was definitely there and now gone. I learned that on one of my cars a few years ago, so I always mark everything with a grease pencil before I take it apart. My wife was in a mood today, so I was not operating at full mental capacity. Had I been paying attention, I would have put it back right the first time. But I guess that little 'issue' gave me confirmation regarding the importance of driveshaft balencing / indexing.

 

The precision joints came from Napa. I asked for them by name and number though, without letting them look it up. They couldn't find a rear part number anyway when I called last night.

 

The Precission's I bought before came from O' Reilly's,,,and they said China on them. So I just gave up on trying to get USA made one's. I'll have to check into it again.

The Napa # is 338,,,,but that's for a long bed. I would think they are all the same. All 3 of mine are for the 2 piece shaft. Do you have a 1 or 2 piece drive shaft.

EDIT:

I just checked Napa's web site. There's lot's of different part #'s. The 338 did not come up. I hope I have the right one.

The right one for the long bed is 351A, and it say's short bed is 330a.

You really need to start at the begining and type in your truck,,there's many variation's. The heavy duty version is twice the money. Almost $40. Maybe that's why I keep going through them.

Here's the link.

http://www.napaonline.com/MasterPage...d=8&SubCatId=1

 

Grease only coming out of 1 cap means the joint is too tight. After I put them in, I put the cross bars on the vise and smack the driveshaft so the caps will go back against the clips and allow room for the grease to come thru.