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#51 |
Second Chance Program
Join Date: Jun 2006
Location: Portland, OR
Posts: 2,642
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Re: weird vibration at speed 60 plus
I have known of semi float axles, (12 bolt in particular), to have bent axle shafts which would do something similar.
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90 Chevy Suburban 2500 5.3 swap/th400/np241/14bltSF/10blt. 77 C20 crew cab Silverado. 396/th400. In work. |
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#52 | |
Registered User
Join Date: May 2009
Location: Motor City
Posts: 9,287
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Re: weird vibration at speed 60 plus
Quote:
In particular the way you separated out the various potential root causes - K
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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/ |
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#53 | |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
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#54 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,781
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Re: weird vibration at speed 60 plus
I've searched and found some like yours but they could be wrong too. Easy to swap yours around.
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#55 |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
Ok, funny thing on my shaft is there is a line scribed where the two joints come together. I might put it back that way and just flip the u joint around and see if that helps.
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#56 | |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
Quote:
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#57 |
Second Chance Program
Join Date: Jun 2006
Location: Portland, OR
Posts: 2,642
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Re: weird vibration at speed 60 plus
I really believe that factory was with the slip at the t-case. But i too have seen it both ways. And as far as the bravery, i was extremely careful to never put myself in real harm while i was doing it. I had it about an inch away from my other truck with it in park and the ebrake set. This way, if the 78 left off the jack stands at 60mph, it would only make it an inch before it slammed into my other truck. No momentum to build up. The other thing is it takes an extraordinarily light throttle to get to 60 with the tires off the ground. Like very light. Then, to top it off, all the time that it was doing 60 sitting still, i was in the cab. Realistically, very little to go wrong when its all done "right".
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90 Chevy Suburban 2500 5.3 swap/th400/np241/14bltSF/10blt. 77 C20 crew cab Silverado. 396/th400. In work. |
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#58 |
Second Chance Program
Join Date: Jun 2006
Location: Portland, OR
Posts: 2,642
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Re: weird vibration at speed 60 plus
Here is a pic from a 76 suburban brochure.
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90 Chevy Suburban 2500 5.3 swap/th400/np241/14bltSF/10blt. 77 C20 crew cab Silverado. 396/th400. In work. |
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#59 |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
Ok, glad to hear you were safe about it. Thanks for the driveshaft shot. Im gonna switch it around tomorrow and see if that fixes this problem finally haha. Thanks
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#60 |
Second Chance Program
Join Date: Jun 2006
Location: Portland, OR
Posts: 2,642
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Re: weird vibration at speed 60 plus
Found another pic showing it at the tcase.
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90 Chevy Suburban 2500 5.3 swap/th400/np241/14bltSF/10blt. 77 C20 crew cab Silverado. 396/th400. In work. |
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#61 |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
Ok guys hopefully I can explain this so it makes sense. I pulled my driveshaft today and I realize why I put the driveshaft on the way I did(backwards). My rear u joint was a 1350 rear diff yoke and driveshaft side also at that end. On the other end that was at the transfer case it was a 1310 joint I believe on shaft and yoke side. So with the joints I had this was the only way I could put it back together. Now to put the driveshaft on the correct way with the slip joint at the tcase I believe I will need a conversion joint of 1310/1350 at the t case and at the rear diff. This seems odd 2 me, but I know the trans was swapped from a th350 to a th400 so this might be why the joints are conversion joints. Anyone have any thoughts or advice before I go buy thses?
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#62 |
Registered User
Join Date: Apr 2013
Location: Pasadena, Maryland
Posts: 160
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Re: weird vibration at speed 60 plus
Sounds like more than just the trans was replaced. Rear or T-case? Has the driveshaft been pieced together from different trucks?
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#63 |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
The rear end is original 14 bolt ff. I was asking myself about the driveshaft too. I dunno if thats what was put in when the turbo 400 was added or how they did it. But a 1310 1350 conversion joint is the only way I could figure 2 make it work. Not taking pictures before I took this thing apart is really biting me in the butt right now.
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#64 |
Registered User
Join Date: Apr 2013
Location: Pasadena, Maryland
Posts: 160
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Re: weird vibration at speed 60 plus
Was the truck an automatic from the factory? What T-case do you have now?
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#65 |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
Yea turbo 350 from factory with 203, now has turbo 400 with 203.
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#66 |
Registered User
Join Date: Apr 2012
Location: Shady Valley, TN
Posts: 25
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Re: weird vibration at speed 60 plus
You need a 1350 slip yoke and a 1350 replacement yoke for the 14 bolt. End of conversion joints. What you have now is a conversion drive shaft.
Matthew or vise versa.. Last edited by lilspike; 10-07-2013 at 01:11 AM. Reason: saw above post after i posted this. |
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#67 |
Second Chance Program
Join Date: Jun 2006
Location: Portland, OR
Posts: 2,642
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Re: weird vibration at speed 60 plus
You know whats funny, i seem to remember mine being just the other way around. I wanted to try flipping mine around but couldn't for some reason and i think thats why. Now i really wonder! I'll have to climb under there and measure but im almost certain i cant flip mine to the way yours is cause the ujoints are different.
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90 Chevy Suburban 2500 5.3 swap/th400/np241/14bltSF/10blt. 77 C20 crew cab Silverado. 396/th400. In work. |
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#68 |
Registered User
Join Date: Jul 2011
Location: WV
Posts: 946
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Re: weird vibration at speed 60 plus
One thing I have noticed on this thread is that you have a 203 case and you say you can feel some of the vibration in the steering wheel. You may want to check out the front driveline also. Loose u joints both in the shaft and the front axle and weights on the shaft.
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72 GMC C2500 402/Th400 first truck (still have) 77 GMC C3500 CC dually Sold ![]() 70 C50 dump truck "Rusty" 87 K10 Suburban Sold 93 K2500 xcab 6.5TD 96 GMC K2500 Suburban 6.5 TD |
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#69 |
Registered User
Join Date: Apr 2012
Location: Shady Valley, TN
Posts: 25
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Re: weird vibration at speed 60 plus
That is a very good point to check the front as well! Would pay to make sure the T/C mounts are in good condition too. Most are deteriorated and squashed after all these years.
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#70 |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
I have the part time kit so my front shaft doesnt spin in 2wd. Its gotta be in this rear driveshaft im sure.
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#71 |
78K & 79C Jimmys
Join Date: Nov 2009
Location: Ottawa Ont CANADA
Posts: 7,901
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Re: weird vibration at speed 60 plus
[QUOTE=y5mgisi;6278510]I really believe that factory was with the slip at the t-case. But i too have seen it both ways. QUOTE]
I believe factory is front,both of mine are front,my rear most u joint went last year.had some vibration,did both
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John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350 |
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#72 |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
Ok guys made some progress today I think. Ran the truck on jackstands up to 60mph and still had the vibration with drums on. Pulled both axleshafts and ran it up to 60 mph. Still had the vibration but it wasnt a rough as when the drums were spinning. The vibration is still apparent without axleshafts in though. Still with axleshafts out, I ran the truck at idle in drive so prob 15mph and climbed under to the driveshaft. Marked it with a sharpie while it was moving. While it was moving the sharpie mark seemed to go all the way around the ds but after I shut the truck off and rotated by hand I could see it had not. The sharpie only contacted on about half of the ds. I did several different lines to be sure and all marked the same half spot on the ds. Also noticed that on my pass side brake drum that I replaced prob 5 years ago(junkyard orginal gm drum) that it has a weight on the face and the driver side drum(original to the truck as far as I know) does not. I looked for a place were the weight might have fallen off but could find no evidence of that. I will post pics of drums. So what have I got here? Anyone have any thoughts? I have a few but wanna see what everyone else thinks before I do anything else. Thanks for reading!
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#73 |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
Driver side
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#74 |
Registered User
Join Date: May 2012
Location: Estacada, Oregon
Posts: 254
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Re: weird vibration at speed 60 plus
While putting it back together I realized the pass drum that I got from the junkyard years back was not a factory gm drum. Has the part number 5117 on it and does not say gm anywhere on it.
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#75 |
Second Chance Program
Join Date: Jun 2006
Location: Portland, OR
Posts: 2,642
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Re: weird vibration at speed 60 plus
That is interesting. Its further interesting to do those runup tests tho isnt it? I had a good time doing that "investigating". Im going to venture to bet you and i both have two issues. Out of balance drums and drivelines. I am contemplating just going to disc brakes in the rear since its so cheap. And then then getting the drive line rebuilt and balanced up at sixstates here in Portland.
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90 Chevy Suburban 2500 5.3 swap/th400/np241/14bltSF/10blt. 77 C20 crew cab Silverado. 396/th400. In work. |
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