Still play in the driveline (I can hear it). - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**COBALT** · 03-28-2002, 12:53 AM

I put this on the "Engine and Drivetrain" forum, but it's not getting any answers, so...
---
Well, I replaced my U-joints a couple of weeks ago, and got the driveline back in the truck finally after some struggling with the center support bearing.
I notice that there's still excessive play in the driveline. I can hear it when I let off the accelerator (there's a slight "clunk"). It's either at the tranny output shaft or its at the differential.

Problem is that the differential was rebuilt in November, and is solid (I've even had it rechecked), but when I was putting the driveline in I noticed there was play in the 3rd member yoke. I had to move it a tiny bit to get the rear U-joint lined up with the yoke!

I'm thinking the driveline is a spline off on the slip-yoke on the tranny output shaft. If I pull the driveline loose, take the play out of the diff. yoke, and put it back in 1 spline over I think the play will dissapear. Any thoughts?

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

*Fast68Chevy* · 03-28-2002, 01:01 AM

rear U joint or carrier bearing are worn

imdarren · 03-28-2002, 01:12 AM

No surprise you didn't get any response from the engine / drivetrain board. I posted a question asking the factory specs for the spark plug gap, and it was NEVER answered. It was on this board however. Darren

**COBALT** · 03-28-2002, 01:39 AM

Fast: Both are brand new and in good shape.

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

aesj2 · 03-28-2002, 02:00 AM

Check the trans mount. The rubber could be torn away from the backing plate. This could cause the trans to "whip" side to side on decel.

**COBALT** · 03-28-2002, 11:21 AM

Yeah, that sounds like a good idea. I remember feeling a little play in the tranny output shaft when I was putting the driveline back in, and remembered thinking I needed to do the rebuild soon on the ole TH400.

The differential was serviced by Randy's Ring & Pinion in November, and inspected in February. No worries there unless the 3rd member yoke has somehow worked its way loose (which is highly unlikely). What's funny is that the 3rd member yoke did have a little bit of play in it. When I was putting the slip yoke on the tranny I realized that the rear U-joint didn't exactly meet the 3rd member yoke, so being tired and cranky I moved the slip yoke one spline over, and moved the 3rd member yoke to match the rear U-joint. Then I tightened everything down.

All three U-joints are brand new, packed, and in damn good shape, including the rear one, which has new U-bolts. Their tight, I checked.

Is it really possible to introduce play into a driveline by messing with the 3rd member yoke, or should I start blaming the transmission for the excess play?

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

71GMC_3/4T · 03-28-2002, 11:59 AM

You may also want to recheck the "timing" of the driveshaft if it's 2 piece. I think GMCPaul has notes on how to do this on his website.
I need to do it on mine someday - I pulled the driveshaft to install a new U-joint when I first got the truck and didn't pay any attention to that part when I reinstalled it. It vibrates a little at highway speeds.

**COBALT** · 03-28-2002, 12:09 PM

You mean balance? I did the usual: mark up the yokes and shafts with white wax pencil to make sure it went back together the same way if that's what you mean. I've had bad experiences before, so I knew what to do. I have no vibration at all. None. It's only on the deceleration I hear a "clunk", and not all the time at that!

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

O'l Buck · 03-28-2002, 12:10 PM

Check that your driveshaft is in phase(ears properly aligned)if it is out of phase, even one tooth, this will cause a vibration at any speed and excessive wear on u-joints.

------------------
'72 Chevy 1/2T 4x4 shortbox stepside 350/350auto on '84
ralleys and 31/10.5s

67 Cutlass convertible
330, 3spd stick

90 GMC Jimmy
350/auto
Chad Stephens
Orleans,NE

**COBALT** · 03-29-2002, 05:17 PM

Well I may have a solution to my slight "clunking" on deceleration in my driveline. This is FYI.

I had a chat w/ Randy's Ring & Pinion about my 3rd member yoke, and the fact that there's some play in it (in rotation).

Turns out the detroit locker often times introduces play in the 3rd member yoke. It's normal: sometimes as high as 1/4 turn of play! The service guy laughed a bit, and said he often gets calls from people convinced something's wrong with their driveline after having a locker put in...

...oh well. I'm still going to check the tranny. I feel kinda stupid. Should have checked with them when I saw the play in the yoke before getting all excited about it.

Thanks all

------------------
'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

03-28-2002, 12:53 AM	#1
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Still play in the driveline (I can hear it). I put this on the "Engine and Drivetrain" forum, but it's not getting any answers, so... --- Well, I replaced my U-joints a couple of weeks ago, and got the driveline back in the truck finally after some struggling with the center support bearing. I notice that there's still excessive play in the driveline. I can hear it when I let off the accelerator (there's a slight "clunk"). It's either at the tranny output shaft or its at the differential. Problem is that the differential was rebuilt in November, and is solid (I've even had it rechecked), but when I was putting the driveline in I noticed there was play in the 3rd member yoke. I had to move it a tiny bit to get the rear U-joint lined up with the yoke! I'm thinking the driveline is a spline off on the slip-yoke on the tranny output shaft. If I pull the driveline loose, take the play out of the diff. yoke, and put it back in 1 spline over I think the play will dissapear. Any thoughts? ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

03-28-2002, 01:12 AM	#3
imdarren Registered User Join Date: Oct 2001 Location: SW Washington Posts: 1,006	No surprise you didn't get any response from the engine / drivetrain board. I posted a question asking the factory specs for the spark plug gap, and it was NEVER answered. It was on this board however. Darren __________________ Washington State 1967 Chevy C10 LWB Rodstoration In Progress. 1972 K20 Cheyenne Super

03-28-2002, 01:39 AM	#4
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Fast: Both are brand new and in good shape. ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

03-28-2002, 11:21 AM	#6
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Yeah, that sounds like a good idea. I remember feeling a little play in the tranny output shaft when I was putting the driveline back in, and remembered thinking I needed to do the rebuild soon on the ole TH400. The differential was serviced by Randy's Ring & Pinion in November, and inspected in February. No worries there unless the 3rd member yoke has somehow worked its way loose (which is highly unlikely). What's funny is that the 3rd member yoke did have a little bit of play in it. When I was putting the slip yoke on the tranny I realized that the rear U-joint didn't exactly meet the 3rd member yoke, so being tired and cranky I moved the slip yoke one spline over, and moved the 3rd member yoke to match the rear U-joint. Then I tightened everything down. All three U-joints are brand new, packed, and in damn good shape, including the rear one, which has new U-bolts. Their tight, I checked. Is it really possible to introduce play into a driveline by messing with the 3rd member yoke, or should I start blaming the transmission for the excess play? ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

03-28-2002, 11:59 AM	#7
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	You may also want to recheck the "timing" of the driveshaft if it's 2 piece. I think GMCPaul has notes on how to do this on his website. I need to do it on mine someday - I pulled the driveshaft to install a new U-joint when I first got the truck and didn't pay any attention to that part when I reinstalled it. It vibrates a little at highway speeds. __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

03-28-2002, 01:01 AM	#2
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	rear U joint or carrier bearing are worn

03-28-2002, 02:00 AM	#5
aesj2 Registered User Join Date: Feb 2002 Location: Ferndale, Michigan, USA Posts: 94	Check the trans mount. The rubber could be torn away from the backing plate. This could cause the trans to "whip" side to side on decel.

03-28-2002, 12:09 PM	#8
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	You mean balance? I did the usual: mark up the yokes and shafts with white wax pencil to make sure it went back together the same way if that's what you mean. I've had bad experiences before, so I knew what to do. I have no vibration at all. None. It's only on the deceleration I hear a "clunk", and not all the time at that! ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

03-28-2002, 12:10 PM	#9
O'l Buck Recovering Truck Driver Join Date: Mar 2002 Location: Orleans, NE USA Posts: 1,883	Check that your driveshaft is in phase(ears properly aligned)if it is out of phase, even one tooth, this will cause a vibration at any speed and excessive wear on u-joints. ------------------ '72 Chevy 1/2T 4x4 shortbox stepside 350/350auto on '84 ralleys and 31/10.5s 67 Cutlass convertible 330, 3spd stick 90 GMC Jimmy 350/auto Chad Stephens Orleans,NE __________________ 67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska

03-29-2002, 05:17 PM	#10
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Well I may have a solution to my slight "clunking" on deceleration in my driveline. This is FYI. I had a chat w/ Randy's Ring & Pinion about my 3rd member yoke, and the fact that there's some play in it (in rotation). Turns out the detroit locker often times introduces play in the 3rd member yoke. It's normal: sometimes as high as 1/4 turn of play! The service guy laughed a bit, and said he often gets calls from people convinced something's wrong with their driveline after having a locker put in... ...oh well. I'm still going to check the tranny. I feel kinda stupid. Should have checked with them when I saw the play in the yoke before getting all excited about it. Thanks all ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.



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