2dogs

Hello All,
The good news is that the electric water pump performed with excellent numbers in 100F heat. So it is on to the next problem..... :cry

Here goes:
I am experiencing a very hard shuddering under heavy loads/throttle - usually happened around 70-75mph. If I let off it stops. If I downshift to D it stops.
I am assuming the tranny.....
So I brought up the Auto temp gauge - during a mountain pass it went from about 222 to 239. That is all in range, correct?

Will the transmission show 'evidence' of a problem? This shuddering happens only after the car is up to operating temperatures and may be difficult to reproduce in the shop.

The car has 35k on it so needless to say I am :mad Anything else to look for
or go forward with transmission replacement?

I have the extended warranty so obviously I will go through Chevy. Can you guys educate me on the questions to ask to make this a smooth diagnostic and replacement?

Also what Chevy dealer in the Bay Area do you suggest?

Thanks!

mackeyred96

I believe these trans's are strong pieces. I still have the stock tran in mine, no shift kit, nothing, with 95,000 miles on it. So don't think with 35k on it yours is shot. I also run high temp numbers with my 3000 stall convertor. My advice would be to find a quaified trans man to chech it out before it becomes a big problem.

PeteL

John I know your trans had not had an "easy" life.

Do you have and maintenance tips for the trans? Fluid changes, filter changes, aux coolers and so forth?

Thanks,

Pete

2dogs

Thanks Mackey.
I am having everything checked for balance and then will have GM service the tranny. It is under warranty so I need to go that route but I would love to talk to an independant shop tranny guy.

I have had great luck with the 4L60 in my 91 Blazer - 210k of wheelin and towing goodiee around the country. I am on my second tranny but I think that is good.

jpee

I'm wondering if his torque converter is staying "locked" when he is hitting the gas.. my converter always unlocks at any speed when I give it more than 1/2 throttle.. (all 3 that I've used) stock, Continental, & Vigilante..

Could it be the converter not unlocking ?

mackeyred96

:confused: I don't think so.

moffitt

Sounds like the converter clutch is going south.

2dogs

Would the lock up/cycling be a HARD hit?
It is a VIOLENT shudder. Imagine a maual tranny with a fluid soaked disk and choppy pressure plate. Have you felt a shudder like that?
But it is happening at speed.
I do have new wheels that I am having re-checked but could you cause a wheel to stop hopping by downshifting? I suppose anything is possible when it comes to harmonics and balancing....

Someone on my K5 site mentioned a pump going out - I could be imagining things but it sure sounds more noisy than usual. I should mention I am hyper-sensitive about the car lately..... Too much stuff happening to it.

moffitt

Oh yes! Is it when it goes to OD or lock up?
Either clutch can shake out your teeth.
Reminds me of my GM tech days and the 700R4 trans when it first came out.
We used to put posi additive in them, shssssssh, don't tell anyone!

2dogs

The symptom seems to ONLY be in OD but - I can't tell if the lock-up is on or off so that is a very good observation.

It seems to happen under acceleration or loads (steep passes on I-5).

If I accelerate too hard it will drop to D and stay smooth 'til OD. Is the torque converter capable of locking in D? Cuz it should happen in D then.....