Tranny in my 'burb going bad?

[chevy_fatman]

I recently bought a 1990 4x4 1/2 ton suburban (old body style) it has a 350 and a 4 speed automatic transmission, first time I drove it back to my place I was driving around 55 MPH and all of a sudden I feel and hear this thumping sound that I could not locate where it was coming from, it also felt like it was "jumping" a bit, it did this only while I was driving on 4th. gear, so I slowed down and down shifted to 3rd gear and drove home like that no more sound or funny noises.

The tranny had been replaced by PO a couple of years before I got the 'burb and I believe it was a used one (probably got it from a junkyard) and the 'burb sat since then because his wife made him buy her a brand new suburban.

Are the internals going bad on my tranny? or does anyone what might be wrong with my 'burb?

I was going to take the 'burb to a garage and service the tranny (flush all oil and replace the tranny filter) but if the tranny is going bad this would be useless.


I would appreciate any advise you guys can give me.

Thak you. Fatman.

[swervin ervin]

Sounds like the typical converter shudder to me. I've got a 92 Chevy van that shudders like a dog. If I put it in OD, it's about undriveable after it warms up. I drive in 3rd all the time, but it still shudders, but nowhere as bad. One thing about the van is the weight and rear gear. I'm thinking it's either a 2.73 or 3.08. The van was a previously a glass installers van that had the racks on each side. This probably contributed to the converter going south. I'm guessing with the load they carried all the time and the high rear gear, causing it to lock and unlock all the time. Of course my tranny is in need of a rebuild too. It slips sometimes going from 2nd to 3rd. I've got a plan to fix mine forever. I also got a 87 van with a good TH400 in it that I was trying to sell. With no takers, I've got a good home for the 400.

[chevy_fatman]

Thanks for the reply Mike, converter huh? I wonder if my tranny will go bad if I just drive the 'burb in 3rd gear (I don't drive out of town often)
I was thinking that the tranny might need to get rebuilt, just didn't want to face the facts

Thanks!

[swervin ervin]

No, it won't hurt a thing to drive it in 3rd all the time. Well, maybe gas mileage a tad.

I'm not sure if just swapping converters would fix this problem. It might, but I've never tried to see. It's also very possible that there may be other things wrong inside the tranny itself. For sure, if you do get it rebuilt or get another one, swap out the converter too. I would recommend not installing a used converter. So many are bad or on the verge of it. Go with a new one.

[chevy_fatman]

I agree with you going with a new converter, if it's already out why taking a chance when putting a used one in? I always try to go with new stuff when I can and I know it'd be worthy,

I'll eventually rebuild the tranny, I just wanted an opinion different than mine weather the tranny would be affected by not using the OD or not, I can live with a not so great gas mileage.

The rebuid will probably cost more than the 600 bucks I paid for the 'burb :p

Gracias for your input Mike.

[fine69]

Hey Paul. It wont hurt it at all to drive it in 3rd. You would have to if you were towing a trailer. Cant tow in overdrive without ruining the tranny anyway.
Gas mileage wont suffer too much if you dont drive it out of town that much.

[chevy_fatman]

Thanks for the reply Mike (fine69) I've had worse gas mileage with my Longhorn, what's the latest update in your extended cab?