Trans Port, Transport Transmission Vibration

[wtp1]

We just installed a used overdrive transmission in my dads 94 transport w/ 3800 engine.and now theres a vibration. the vibration is even when vehicle is in park. The vibration gets worse in gear and while driving. Warmer it gets it seems to get worse. It's not a bad vibration but its enough where when your at a stoplight you can feel it in the steering wheel. Feels just like when a cars idle is turned way down. Thats not the problem but it feels like that. The thing was fine until the tranny was replaced so I now it's not a engine problem. Mounts all seem fine. The vehicle drives great. All gears seem to be shifting right and where they should be sifting. just got this vibration that will drive you nuts. Any ideas whats going on?

[LMP]

Your description seems to point out to a mechanical contact and although "Mounts all seem fine"....I'd try to find if they have been reinstalled slightly out of alignment and let some part of the engine/transmission unit/exhaust system contacting other parts of the body...
Is the vibration totally in sync with engine rpm or does it come randomly ?
...ANd by the way, just to document the operation for others....how was the transmission swap performed? Did you drop the entire subframe with engine or , as some have done, split the subframe and change the transmission "in situ" ? Any pictures of the operation ? ANd what was the problem with the original transmission ?

[wtp1]

Originally Posted by LMP

Your description seems to point out to a mechanical contact and although "Mounts all seem fine"....I'd try to find if they have been reinstalled slightly out of alignment and let some part of the engine/transmission unit/exhaust system contacting other parts of the body...
Is the vibration totally in sync with engine rpm or does it come randomly ?
...ANd by the way, just to document the operation for others....how was the transmission swap performed? Did you drop the entire subframe with engine or , as some have done, split the subframe and change the transmission "in situ" ? Any pictures of the operation ? ANd what was the problem with the original transmission ?

He lost drive. Subframe was split. Will have to dbl check on if the vibration is in sync with RPM. The mechanic that put it in said that when he pulled the trans filter to put the new one the old fluid looked good (yes there's new fluid put in) and there was very little metal shavings in the pan. no more then usual

[Jrs3800]

I also wonder if a mount has failed... The front trans mount and rear trans mounts o these are known to go bad, just as the front engine mount is known to fail as well..

Its possible for the Tq converter to have a bit of wobble in it as well.. Did the mechanic inspect the Bushing in the Torque Converter?

You guys sure its not a dead on Misfire ?

[wtp1]

well it was working fine ecept for the vibration. now as of yesterday it's not shifting into overdrive until 4500 rpm's. trying another tranny on thursaday.

[LMP]

Originally Posted by wtp1

... trying another tranny on thursaday.

...ok...if you could take a few pictures of the operation, it might document future posts specially for those nervous about transmission swap projects. The split sub frame method is interesting....
.... any problem checking for or finding transmission with same gear ratio?
...high rpm shifting might be caused by failed/disconnected transmission modulator (disconnected vacuum line to modulator acts as full throttle applied) ...it would apply to all gear shifts, though, not only O/D....but....4500 rpm in 3rd gear before shifting to 4th makes for somewhat a little bit above speed limit,.. if I understand correctly... any comment ?....

[Jrs3800]

The good thing about the 94-95 3800 TS is that a lot of different transmissions can be used... You could use anything with a 3.06 from 94-97 but use the torque converter that comes with the transmission... The 96-97 Torque converters are actually a bit better than the older torque converters as far as TCC lining...

The VSS on the 94-95 TS has a 31 Tooth reluctor the 96-97 has a 30 tooth reluctor, this will equate to a 1.5 Mph or so difference at 60 Mph... But any of these transmissions can be used and are Plug and play...

For the Most part these Transmissions would come out of an H Body car... LeSabre, Bonneville, Olds 88 or LSS.... Option code FW2

Also before the trans is installed, the Internal coolers in the radiator depending on you having one or 2 coolers... The coolers need to be flushed out to make sure they are not plugged with trash, if they are plugged with trash you need to get an AUX Cooler..

[Jrs3800]

Originally Posted by LMP

...ok...if you could take a few pictures of the operation, it might document future posts specially for those nervous about transmission swap projects. The split sub frame method is interesting....
.... any problem checking for or finding transmission with same gear ratio?
...high rpm shifting might be caused by failed/disconnected transmission modulator (disconnected vacuum line to modulator acts as full throttle applied) ...it would apply to all gear shifts, though, not only O/D....but....4500 rpm in 3rd gear before shifting to 4th makes for somewhat a little bit above speed limit,.. if I understand correctly... any comment ?....

I know I have pictures somewhere... I have done this 2 times already on this van... and am about to drop the cradle complete to do some more modding to the engine and replaced the trans as I fried the TCC Clutch...

Also on the 4T60E the Vac Modulator only controls shift firmness, has nothing to do with shift time, shift time is 100% electronic... By the sound of it this trans blew a lip seal and is having a hard time getting enough pressure to apply the clutch pack causing a delayed shift... Very bad..

Interested to see how this plays out..

[LMP]

Originally Posted by Jrs3800

I... on the 4T60E the Vac Modulator only controls shift firmness, ..shift time is 100% electronic... ..

Interesting info; I thought that vac modulator in someway overrided the electronic shift....when there is one. IN fact, after 1996 or 97, the vacuum modulator is gone, anyway.

[Jrs3800]

All of the 91-99 4T60E use the Vac Modulator strictly for line pressure control... The solenoids command the shift... You can select manual 1, but if you hold your foot on the floor the PCM will force a 2nd gear shift...lol

97 was the first year some models used the 4T65E in this unit the Line pressure was controlled electronically...

[wtp1]

Replaced trans with another one and runs and drives great. Thanks for all the help