Minor idle vibration after trans rebuild

1996 Chevy S-10 (AT), 2.2L, 79K miles

I put my S-10 in the shop last week to have the transmission rebuilt. Got it back on Saturday and it’s now shifting beautifully and all.

There’s only one little oddity: the truck now has a very slight vibration when sitting at idle, and it most definitely was not doing that before the rebuild. There is no effect on performance, shifting, or anything…I only notice it because I know it wasn’t there before.

When I picked it up after the work was done, the shop (a great local independent) advised that I bring the truck back in after about two weeks to have a free-of-charge check of everything, to make sure their work is holding together. I’ll be going Friday since the entire next week has me in Florida, and I plan to mention this slight case of the shakes to them.

Is it possible that maybe a bolt somewhere wasn’t completely tightened down, or maybe a motor mount got jostled in the process of trans removal? I can’t see anything obvious. The engine does vibrate just a bit, but that’s hardly unusual. Maybe I’m just feeling a fully functional trans instead of one that slips all the time…

are you driving to fla?
If you drive it while it something is wrong it can void any warrenty.
Call shop and ask them what to do, write down everything!

I can only agree with hd72,you know something is wrong. Maybe.

Torque converter not balanced maybe… The trans shop should be able to determine that. It happens sometimes. I have had quite a few rebuilt and new converters be bad.


No, it’s not being driven to Florida. I’m flying down.

According to the service notes, the converter was rebuilt so maybe they just need to adjust or redo it somehow. I’ll be sure to mention it. Thanks!

My concern is did they support engine properly while tranny was out? Also the flex plate could be slightly warped. is that new?

Did they accidently drop your drive shaft? Does vibration vary with engine speed? or is it just noticeable at idle like you said?

Do NOT shirk at them wanting to check up on it. I’ve never heard of a shop doing that, that’s awesome!

long shot…what about the kick down cable(did I say that right)?

Vacuum might be an issue.

Let us know what you find friend.

Nope, it is at idle only. No trouble at all once you get moving or give it a bit of gas.

Yeah, this is a great shop. One year/12K mile warranty, and they insist it’s brought back for a check-up no more than 15 days after pickup. I’ll get it back to them Thursday or Friday, will post what they find.

The Iron Duke will vibrate noticeably at idle, as will any 4-banger.

Ever wonder why women love to ride on Hogs with those two huge cylinders and all that vibration…oops, I digress.

The reason you didn’t notice it before is just as likely that, now there is less fluid slipping past old seals and valves, the looseness of the clutches, slipping torque converter and other stuff.

So, just slip into neutral at the stop light and save a slight amount of wear and some gas, because it takes less power to idle in neutral.

Negative on the neutral at idle situation. You want to be ready to go when the light changes. You would really accept slipping it into neutral everytime you stop? Not playing the radio also saves gas you may want to try that :))

Assuming this is not an engine induced problem (mount, engine performance, etc.) then some possibilities could be:
Flexplate/converter imbalance.
Loose bolts/nuts on a transmission mount, bellhousing bolts, etc.

Since rebuilds can mean different things, was your actual transmission rebuilt or was it swapped out on an exchange basis?
If the latter, just wondering if a worn out front pump bushing on a shaky reman unit could be allowing the converter to wobble a bit due to bushing wear and flexplate movement, or flex?

Sorry shatto, but shifting into neutral doesn’t make this go away. It’s present regardless of gear.

I checked underneath for any obviously loose bolts, but didn’t see any. Can’t see real good without putting it on a lift anyways.

As far as I know, the original transmission was removed and rebuilt. They never asked about replacing or swapping out for another unit.

Got it over to the shop for the warranty check-up today. The mechanic took it for a bit of a drive and noted how great it shifts, but also noticed the idle vibration. They’re way too busy at the moment to actually get to it, so he recommended that I bring it in after I get back from FL so they can take a good look at it. I brought up the idea of the torque converter possibly being unbalanced, and he said it’s certainly a possibility.

So that’s where we’re at. Trans operation is beautiful, but they want to look at what’s causing the vibration and correct it, if possible. End of the month is the soonest I can get it to them, so the next update will be coming then. Keeping you posted…


Got it over to the shop on Monday to have them look at things and see what’s causing the vibration. The tech called me and said he couldn’t find anything wrong transmission-related.

I mentioned the thought of an unbalanced converter, but he dismissed that saying if that were the case, the vibration would get worse when you give it some gas; the vibration disappears when engine RPMs move anywhere past idle speed.

So I suppose that’s that. Everything looks good to them, and that’ll work for me.