rear end shudder - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**gmc 2500 4x4** · 05-12-2023, 05:12 AM

im having a slight issue, 69 gmc k2500, all redone, i went from 4:56 gears to 3:54. it now has a bb 402 and original sm465 trans, and rockwell 221. im getting a shudder when slowing down in 2wd, even when i push in the clutch. would the gearing change affect the t/case? has a 4'' lift also, and i did shim the rear axle for driveshaft alignment...

**kwmech** · 05-12-2023, 06:39 AM

Any other description besides 'shudder'? only thing that comes to mind is while applying the brakes

**gmc 2500 4x4** · 05-12-2023, 06:56 AM

Almost feels like something is binding up with no brakes applied

**HO455** · 05-15-2023, 08:56 PM

Do you have a clutch style Posi?

**gmc 2500 4x4** · 05-16-2023, 04:48 AM

Quote:

Originally Posted by HO455

Do you have a clutch style Posi?

i do not, i need to jack it up and run it see what i see, this has the carrier bearing also which is new.

**gmc 2500 4x4** · 06-02-2023, 09:52 AM

i pulled out the degreed shims, also gonna start over and bolt up the rear like its written in my books. its only a 4'' lift so im going to try with out shims

**jeffahart** · 06-02-2023, 10:53 AM

First thougt for me is something is loose or broken. Nut and bolt everything while you're under there. An easy 20 minute sanity check. You shouldn't have to play with angles. Read your angles and shim appropriatly, it's all that's needed. How about those bearings?

j

**gmc 2500 4x4** · 06-02-2023, 11:27 AM

Rear was all redone, like i said there is a procedure and not sure if I had all tension out of springs and shackles or proper torque on u bolts. It's what happens when u build something and few yrs later u 4get things...lol keep ya posted

**gmc 2500 4x4** · 12-23-2023, 07:14 AM

when i let off the throttle the pinion angle changes giving me that vibration, been adjusting the angle and seems better. i may use this kit https://www.ebay.com/itm/165624965840, whats yur opinion?

cj847 · 12-24-2023, 05:32 PM

I think you are on the right track looking at u joints. I bet you can reuse your yoke. Also check your center support bearing.

**gmc 2500 4x4** · 12-24-2023, 05:38 PM

When you decelerate and brake its worse as the pinion is nosing down even more leading me to believe it's binding. I'll get it

geezer#99 · 12-24-2023, 08:53 PM

Are your spring packs stock with leaf clamps. Also known as rebound clips.

**gmc 2500 4x4** · 12-25-2023, 08:43 AM

4'' lift springs and u bolts

geezer#99 · 12-25-2023, 01:10 PM

Post a pic of your springs etc.

**gmc 2500 4x4** · 03-30-2024, 08:41 AM

http://67-72chevytrucks.com/vboard/s...d.php?t=220466 got my answer #25

05-12-2023, 05:12 AM	#1
gmc 2500 4x4 Senior Member Join Date: Mar 2012 Location: ripley ny Posts: 2,959	rear end shudder im having a slight issue, 69 gmc k2500, all redone, i went from 4:56 gears to 3:54. it now has a bb 402 and original sm465 trans, and rockwell 221. im getting a shudder when slowing down in 2wd, even when i push in the clutch. would the gearing change affect the t/case? has a 4'' lift also, and i did shim the rear axle for driveshaft alignment...

05-12-2023, 06:56 AM	#3
gmc 2500 4x4 Senior Member Join Date: Mar 2012 Location: ripley ny Posts: 2,959	Re: rear end shudder Almost feels like something is binding up with no brakes applied

05-15-2023, 08:56 PM	#4
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,289	Re: rear end shudder Do you have a clutch style Posi? __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377

06-02-2023, 09:52 AM	#6
gmc 2500 4x4 Senior Member Join Date: Mar 2012 Location: ripley ny Posts: 2,959	Re: rear end shudder i pulled out the degreed shims, also gonna start over and bolt up the rear like its written in my books. its only a 4'' lift so im going to try with out shims

06-02-2023, 10:53 AM	#7
jeffahart Senior Member Join Date: May 2012 Location: Scottsdale, AZ Posts: 1,906	Re: rear end shudder First thougt for me is something is loose or broken. Nut and bolt everything while you're under there. An easy 20 minute sanity check. You shouldn't have to play with angles. Read your angles and shim appropriatly, it's all that's needed. How about those bearings? j __________________ White K20

05-12-2023, 06:39 AM	#2
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,599	Re: rear end shudder Any other description besides 'shudder'? only thing that comes to mind is while applying the brakes

06-02-2023, 11:27 AM	#8
gmc 2500 4x4 Senior Member Join Date: Mar 2012 Location: ripley ny Posts: 2,959	Re: rear end shudder Rear was all redone, like i said there is a procedure and not sure if I had all tension out of springs and shackles or proper torque on u bolts. It's what happens when u build something and few yrs later u 4get things...lol keep ya posted

12-23-2023, 07:14 AM	#9
gmc 2500 4x4 Senior Member Join Date: Mar 2012 Location: ripley ny Posts: 2,959	Re: rear end shudder when i let off the throttle the pinion angle changes giving me that vibration, been adjusting the angle and seems better. i may use this kit https://www.ebay.com/itm/165624965840, whats yur opinion?

12-24-2023, 05:32 PM	#10
cj847 Registered User Join Date: Sep 2016 Location: Ozark, MO Posts: 568	Re: rear end shudder I think you are on the right track looking at u joints. I bet you can reuse your yoke. Also check your center support bearing.

12-24-2023, 05:38 PM	#11
gmc 2500 4x4 Senior Member Join Date: Mar 2012 Location: ripley ny Posts: 2,959	Re: rear end shudder When you decelerate and brake its worse as the pinion is nosing down even more leading me to believe it's binding. I'll get it

12-24-2023, 08:53 PM	#12
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,712	Re: rear end shudder Are your spring packs stock with leaf clamps. Also known as rebound clips. Last edited by geezer#99; 12-24-2023 at 09:27 PM.

12-25-2023, 08:43 AM	#13
gmc 2500 4x4 Senior Member Join Date: Mar 2012 Location: ripley ny Posts: 2,959	Re: rear end shudder 4'' lift springs and u bolts

12-25-2023, 01:10 PM	#14
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,712	Re: rear end shudder Post a pic of your springs etc.

03-30-2024, 08:41 AM	#15
gmc 2500 4x4 Senior Member Join Date: Mar 2012 Location: ripley ny Posts: 2,959	Re: rear end shudder http://67-72chevytrucks.com/vboard/s...d.php?t=220466 got my answer #25

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