The stock 700r4 in my 88 IrocZ just turned 110,000 miles and im beginning to see the signs of age. there is a vibration somewhere in the drivetrain that only occurs while in overdrive and getting on the accelerator or while climbing a steep grade. i originally thought U-joint but considering it only occurs in a specific gear I'm now more concerned about the transmission. so my thoughts are split and I'm unsure if a complete trans swap is in order or if i can just purchase a transmission overhaul kit.

 

110k is nothing. My 4L60 made it to 264k before it started slipping

Check for loose parts around the trans/exhaust. Rattles arent common on transmissions

 

its not so much a rattle as what started as a soft vibration and has now grown to a shutter and time the car is in OD and under hard acceleration.

 

Check your tranny and motor mounts.
As for the life of the transmission, that depends on how it was taken care of.
Dark burnt smelling fluid, do a tranny service and it will go out sooner.

 

I'm the second owner of the car and it had been well take care of and regularly serviced... as far as i know the problem started shortly after i purchased the vehicle and drove it from where i was stationed in southern arizona home to northern nevada. the problem has only grown worse during the cars treck from carson city nevada out to Ft.Benning GA. you stated that a rebuild would only make it go out sooner, why is this? and if a full replacement is in order, would TCI be a good direction.

 

Before you waste a lot of money and time worrying find a tranny shop you can trust and ask for an inspection. Even if you can trust them tell them all you want is an inspection and if it's good a full service and that you would probably sell the car if it needed a tranny.

Serviced and little to no towing they will last 200-250K and some more!

 

No, I stated dark burnt smelling fluid and a tranny service, not rebild, would make it go out sooner. So many people neglect theri transmissions and think a fluid and filter change will bring it back to life. Thats not true.

You should also check, along with the mounts, the u-joints and the drive shaft. Look for any dents and there should be a small weight welded to one end. If that weight was thrown it could vibrate.

 

ok thank you both, i misunderstood mad. i'll check into those things once the car arrives on thursday, i have some family driving it out and just babying it out here till i can get a better look.

 

as mentioned above,110,000 mi usually is not a
concern at all with a 700r4
A couple things to check if there is driveshaft vibration
and u-joints are good are to make sure the pinion nut
on the axle hasn't backed off and made the pinion
bearings loose(usually there is groaning,clunking and
other evidence if the bearings are loose)Also check
the condition of the bushing in the tranny's tail
housing where the slip yoke runs-if its too loose, that
can cause runout of the driveshaft as well as affecting
alignment of tranny internals.

 

no groaning or clunking, the only noise i get is a "ticking" or clicking when the car is in a low gear yet high RPM's like pulling through a parking lot... but i think its unrelated because there is no vibration at that point. only accelerating to pass for instance in overdrive, i don't think its the driveline as much as maybe that particular gear, if i drop down to drive there's not so much of a shake.

 

Maybe it's a torque converter issue - they are supposed to lock in 3rd and 4th gear under lower acceleration, and unlock under higher accelerations (like passing). Might have an issue with the converter or the solenoid that controls the lockup. Sounds like your may be 'hunting' when accelerating (can't decide if it needs to lock or not).

 

is the solenoid an internal or external part somewhere on the trans. sorry for slow response times, training tends to sideline the car.

 

and also i've heard that there is a problem with shifting related to engine temperature being too low... i've upgraded the cooling system, but maybe i've got it running too cool.

 

not trying to thread jack here but i have the same issue/problem.
my 700s going on 180k and its not leaking or slipping but i have a horrible vibration at idle from the tranny..
ill check all my bolts and motor mounts
could a filter fluid change at this point in the transmissions life kill it?

 

If you feel the TCC is constantly engaging and disengageing while cruising then you may just need to replace the Coolant Temp Sensor. A bad one will cause that type of driving issue.
And yes, the soleniod is inside.

 

That depends on the condition it is in now. Its not the fluid change that kills it, its the lack of maintenance.
Check your transmission mount for the vibration.