High Speed Vibration

[Dr_Snooz]

I have a high speed vibration that happens when I get much over 55 and continues as I go faster. I've checked U-joints for slop, replaced the tires and wheels and checked the wheel bearings for excessive play but everything seems fine. There is zero vibration coming through the steering wheel, so I assume it's coming from the rear. The rear diff pinion seal is leaking, but that's all the clues I have. Anyone have some ideas for me?

[MrFiveOh]

I have a high speed vibration that happens when I get much over 55 and continues as I go faster. I've checked U-joints for slop, replaced the tires and wheels and checked the wheel bearings for excessive play but everything seems fine. There is zero vibration coming through the steering wheel, so I assume it's coming from the rear. The rear diff pinion seal is leaking, but that's all the clues I have. Anyone have some ideas for me?

what transmission do you have?

[82silverado]

If the pinion is leaking check your fluid level. Check for up and down play at diff input. Check for play at transmission output also.

[philo_beddoe]

I have a high speed vibration that happens when I get much over 55 and continues as I go faster. I've checked U-joints for slop, replaced the tires and wheels and checked the wheel bearings for excessive play but everything seems fine. There is zero vibration coming through the steering wheel, so I assume it's coming from the rear. The rear diff pinion seal is leaking, but that's all the clues I have. Anyone have some ideas for me?

Uh oh.... (been there-done that,,,twice!)

Quick easy fix, new engine new tranny.

[Dr_Snooz]

Quick easy fix, new engine new tranny.

Oh. I see. If that's the quick, easy fix, I shudder to think what the long and difficult one is! LOL

[MrFiveOh]

Quick easy fix, new engine new tranny.

Oh. I see. If that's the quick, easy fix, I shudder to think what the long and difficult one is! LOL

I would check trans mount. And then i would check the bolt holes where the trans mount sits. On my 350 my trans mount it part of the transmission case and it has a crack at the bolt hole so i have to replace the whole thing. you may be able to just replace the tailshaft housing

[Dr_Snooz]

I'll check that out. Thanks!

[philo_beddoe]

Lol! No it wasnt easy, long and expensive and tons of anxiety. Owning and working on classics can be expensive and challenging.  But the new stuff is complicated and boring,,so...

[76K20]

I have the same problem. I've replaced all the wheel bearings, tires, rims, u-joints and rear pinion bearings.  The trans was rebuilt, 700 R4.  All that's left is the drive shaft and flex plate.

[Spoonbill]

I have an 87 c10 305 tbi 700 r4the same issue. The vibration starts about 35 and just gets worse the fast you go. I have changed everything there is to change and no luck. I need to mentio that my truck only has 66,000 original documented miles. We have owned it since it was new. I have even had my mechanic look at it and he doesn't see anything wrong. He said the only thing it could be is the drive shaft but you wouldn't think it would be that with only 66,000 miles

[Dr_Snooz]

My mount looks good. No chunks missing or anything. Not sure if it's too hard or not.

The truck always goes into Reverse with a mighty clunk. I'm told by the experts here that the transfer case is causing that. The transfer case also has the tell-tale orange paint markings indicating that it came from a scrap yard. How likely is it that the vibration is coming from there? I really feel the vibration when I put my hand on the trans tunnel and can also feel it in the transfer case shift lever to a lesser degree.

[arby87]

I used to have that huge "ker-CLUNK" when going into reverse- but I do not know which component it was that fixed it.

I had the entire rear drivetrain rebuilt- from the output section of the transfer case, through the drive line, and the entire rear differential/axle assembly rebuilt. The P.O. of my truck had swapped out the stock 700R4 for a TH400 along with a 4" lift, but didn't deal with the changes in drive shaft length or change in geometry.

When I was searching through these forums before concerning that clunk, I did come across some threads talking about needing to grease up the bearings in either end of the drive shaft as part of the normal maintenance schedule of these trucks. I would look into that before thinking of something more serious. If your pinion seal is leaking, there might be an issue with your rear diff causing the clunk (too much play in the diff itself).

During my rear diff rebuild (which had both the pinion seal and the rear cover leaking) the shop found that the diff casing itself had been damaged because at some point in time one of the small bolts inside had backed off and went flying around in the diff housing before being ejected through the rear cover. Not saying you might have the same issue, but I would start looking into getting that diff rebuilt to ensure nothing as drastic happens to you.