The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1960 - 1966 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 05-09-2024, 11:58 PM   #1
SkinnyG
Registered User
 
SkinnyG's Avatar
 
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,246
Driveline angles: Is 0.5° really killing me?

I have a mild vibration between 59 and 61 mph. It comes and goes. It is not tire or driveshaft balance. It is not consistent.

My drivetrain is 1.7° pointing down and my pinion is 1.2° up. My driveshaft is 0.7°.

I built it with a small discrepancy to account for bushing compliance.

If I air the truck up or down it does not change the vibration.

Is the 0.5° really causing all my problems?
__________________
1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, boosted-LS
1977 Silverado: Shortboxed & dropped, potato-potato
V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag
Lotus Super 7 Replica: Scratch-built street-legal rollerskate
SkinnyG is offline   Reply With Quote
Old 05-10-2024, 07:06 AM   #2
hewittca
Registered User
 
hewittca's Avatar
 
Join Date: Jun 2014
Location: Mocksville, NC
Posts: 1,758
Re: Driveline angles: Is 0.5° really killing me?

I'm interested to see what feedback you get on this. I am doubtful that a half degree difference in your driveshaft angle would cause a vibration. The angle probably changes by more than a half degree just going through normal suspension travels. I also have a similar problem with my truck. I have done countless tests changing wheels, tires, driveshaft angles, pinion angle, in gear, coasting, etc. Throughout all those tests I have had the same vibration that is sometimes there, sometimes not. I describe it as more of a wobble. Feels like it's in the rear but sometimes migrates to under my seat. The only thing that even changed the feel of the vibration was putting wider wheels on the rear of my truck. With those the vibration was more intense. My only conclusion so far is that I am just hitting a resonant frequency of my truck that I have introduced due to all the heavy modifications I have done to it. Currently, my only solution is to either drive above or below that mph window! If I get motivated enough, I will probably try swapping to poly bushings and maybe try to find stiffer springs or shocks.
__________________
Builds: Green Gus the 68 C10 | Bluey the 72 1500 | Lowly the 70 C10
-
Instagram: @dr.hewitt
-
C10 Concept/Development Photos: Master Thread
hewittca is offline   Reply With Quote
Old 05-10-2024, 07:41 AM   #3
Keith Seymore
Registered User
 
Keith Seymore's Avatar
 
Join Date: May 2009
Location: Motor City
Posts: 9,213
Re: Driveline angles: Is 0.5° really killing me?

Quote:
Originally Posted by SkinnyG View Post

Is the 0.5° really causing all my problems?
No.
__________________
Chevrolet Flint Assembly
1979-1986
GM Full Size Truck Engineering
1986 - 2019
Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926
My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524
Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/
Keith Seymore is offline   Reply With Quote
Old 05-10-2024, 07:43 AM   #4
Keith Seymore
Registered User
 
Keith Seymore's Avatar
 
Join Date: May 2009
Location: Motor City
Posts: 9,213
Re: Driveline angles: Is 0.5° really killing me?

Quote:
Originally Posted by SkinnyG View Post
I have a mild vibration between 59 and 61 mph. It comes and goes. It is not tire or driveshaft balance. It is not consistent.
How do you know it is not tire or driveshaft balance?

K
__________________
Chevrolet Flint Assembly
1979-1986
GM Full Size Truck Engineering
1986 - 2019
Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926
My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524
Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/
Keith Seymore is offline   Reply With Quote
Old 05-10-2024, 12:29 PM   #5
SkinnyG
Registered User
 
SkinnyG's Avatar
 
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,246
Re: Driveline angles: Is 0.5° really killing me?

I've balanced the tires, I've moved the tires on the rim, I've watched the tires on the balancer and on the vehicle at speed on the lift.

I'm also foolishly assuming the driveshaft I had made and balanced was actually balanced properly; I have no way of checking, other than I can physically see that it HAS been balanced.

The trans is rebuilt, with all new bushings. The axle bearings are new. I changed the poly trans mount to rubber.

The engine mounts are poly 4-link bushes, and pretty rigid.

The vibration feels a bit like a "wagging" from the back of the truck.

The fact that it's inconsistently cyclic makes me think it's driveline.

I've chased a similar "wagging" vibration for YEARS in my squarebody and never fully got it resolved.
__________________
1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, boosted-LS
1977 Silverado: Shortboxed & dropped, potato-potato
V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag
Lotus Super 7 Replica: Scratch-built street-legal rollerskate
SkinnyG is offline   Reply With Quote
Old 05-13-2024, 12:51 AM   #6
Short 3/4
Registered User
 
Join Date: Jan 2017
Location: Los Osos Ca
Posts: 554
Re: Driveline angles: Is 0.5° really killing me?

I’m going to be following this one closely, as I’m experiencing EXACTLY the same thing. Have done everything same as you, plus much much more. Have had two custom driveshafts made (very long story), plus everything else possible either replaced or rebuilt. Ironically it’s not my old abused Chevy having the problem, it’s smooth as glass. It’s a Toyota truck (oops, can I say the “T” word here without being thrown out for obscenity?) Being a 4wd I was able to take out the rear driveshaft and run it in front wheel drive. When the problem went away I first assumed driveshaft, but now I’m convinced it’s being transmitted rather than caused by the driveshaft.
Unfortunately I’m out of ideas, so hopefully I’ll once again learn something useful on this forum.
Good luck on your troubleshooting,
Tom
__________________
65 short stepside K10
292-SM420-T221
8 lug closed D44 front
NoSpin HO72 4.10 rear
Short 3/4 is offline   Reply With Quote
Old 05-13-2024, 09:23 AM   #7
Braunschweiger
Registered User
 
Join Date: Aug 2020
Location: Braunschweig, Lower Saxony, Germany
Posts: 804
Re: Driveline angles: Is 0.5° really killing me?

I've tried everything, with vibrations and noises.
I've now re-mounted and adjusted the differential, new axle shafts and new bearings,
it got better but I still had a slight resonance, now I've put the camper top on and the vibrations were back,
now I've checked the angles of the gearbox, drive shaft and differential and that was a disaster,
the Pontiac axle was welded in with a 2° negative,
I've now fitted 4°+ axle wedges, test drove today and I have a big grin on my face, it now drives very smoothly, up to 80 mph.
I'm very satisfied.
__________________
-------------------------------------------

Greetings Harald

My 62 build thread
http://67-72chevytrucks.com/vboard/s...d.php?t=829782

Last edited by Braunschweiger; 05-13-2024 at 12:46 PM.
Braunschweiger is offline   Reply With Quote
Old 05-13-2024, 09:25 AM   #8
Braunschweiger
Registered User
 
Join Date: Aug 2020
Location: Braunschweig, Lower Saxony, Germany
Posts: 804
Re: Driveline angles: Is 0.5° really killing me?

Double
__________________
-------------------------------------------

Greetings Harald

My 62 build thread
http://67-72chevytrucks.com/vboard/s...d.php?t=829782
Braunschweiger is offline   Reply With Quote
Old 05-13-2024, 01:11 PM   #9
pdxhall
Senior Member
 
pdxhall's Avatar
 
Join Date: Mar 2011
Location: Tucson, Arizona
Posts: 2,079
Re: Driveline angles: Is 0.5° really killing me?

I'm just throwing this out there. have you checked out the centering of the rear end? Are the rims exactly the same distance from the wheel wells?
__________________
Sanity'66
http://67-72chevytrucks.com/vboard/s...d.php?t=515110
Long bed, Fleetside, Small back window

I've Done So Much, With So Little, For So Long, That Now I Can Do Anything With Nothing.
pdxhall is offline   Reply With Quote
Old 05-13-2024, 10:04 PM   #10
SkinnyG
Registered User
 
SkinnyG's Avatar
 
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,246
Re: Driveline angles: Is 0.5° really killing me?

Keith, you might still be that genius!

Today, as I was tail-wagging my way to work, I thought to myself "what if it is actually the fronts causing all this..."

I need a few more commutes to confirm, but I rotated one front tire on the rim and balanced both, and the vibration appears gone.

Could my butt-dyno have been lying to me all along???
__________________
1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, boosted-LS
1977 Silverado: Shortboxed & dropped, potato-potato
V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag
Lotus Super 7 Replica: Scratch-built street-legal rollerskate
SkinnyG is offline   Reply With Quote
Old 05-14-2024, 10:45 PM   #11
SkinnyG
Registered User
 
SkinnyG's Avatar
 
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,246
Re: Driveline angles: Is 0.5° really killing me?

Today's commute was very nice at 60mph.

There are other vibrations, vibrations that say "too much polyurethane," but not the hippy-shake-shake that had before re-balancing the fronts. Interesting.

We'll see tomorrow's commute.
__________________
1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, boosted-LS
1977 Silverado: Shortboxed & dropped, potato-potato
V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag
Lotus Super 7 Replica: Scratch-built street-legal rollerskate
SkinnyG is offline   Reply With Quote
Old 05-15-2024, 06:52 AM   #12
Keith Seymore
Registered User
 
Keith Seymore's Avatar
 
Join Date: May 2009
Location: Motor City
Posts: 9,213
Re: Driveline angles: Is 0.5° really killing me?

Quote:
Originally Posted by SkinnyG View Post
Keith, you might still be that genius!

Today, as I was tail-wagging my way to work, I thought to myself "what if it is actually the fronts causing all this..."

I need a few more commutes to confirm, but I rotated one front tire on the rim and balanced both, and the vibration appears gone.

Could my butt-dyno have been lying to me all along???
Still?!

(lol)

All I know is - when you've tried everything and nothing worked it is time to go back and challenge some of those original assumptions.

K
__________________
Chevrolet Flint Assembly
1979-1986
GM Full Size Truck Engineering
1986 - 2019
Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926
My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524
Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/
Keith Seymore is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 07:36 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com