Question: Normal TH350 opertion in 3rd gear at low RPMs

[KANE]

Normal TH350 operation in 3rd gear at low RPMs

I'll admit it- I'm more familiar with EFI, induction, and other aspects than I am with the TH350 (non lock-up) and how to troubleshoot it past basic operations (fluid, shift points, detent, modulator).

So, here is what I am experiencing...

The tranny seems to hold 3rd gear at too low an RPM. It shifts fine from 1-2-3. It will downshift (via th detent and/or modulator) just fine.

However, once it gets to third it seems to hold 3rd gear as I decelerate- even down to 1k rpm (~20mph cruising in a residential) and won't let go until the modulator or detent tells it to. I'd say it **feels like** a 700R4 swap with its lock-up accidentally left engaged via a toggle at a low speed (for those who have done this, that might make sense).

I get the idea it is going into 3rd and staying there- even when I slow down to where I think second makes more sense (is this just paranoia?).

This is recent- like within the last 3 weeks. I don't remember that it behaved like this before. I didn't drive it for a couple weeks as I was putting the engine in, but since then the tranny just seems a bit... off. Maybe condensation from not being driven for a couple of months and dirty fluid.

Am I paranoid or does this seem a bit low to hang onto third?

FWIW, I know I need to change the filter and fluid, but it doesn't leak and doesn't slip. There aren't chunks of debris in the fluid- it is just dirty in appearance.

 

[Curtis]

i would check for a vacuum leak somewhere....

 

[gmjunkie]

Try tightening the detent cable 1 notch and see if that helps!

 

[KANE]

Try tightening the detent cable 1 notch and see if that helps!

No dice. Still holds third at very low RPMs...

i would check for a vacuum leak somewhere....

Actually, a vacuum leak would make the tranny think it is near wide open. No leaks though...


Any other ideas?

 

[gmjunkie]

No dice. Still holds third at very low RPMs...



Actually, a vacuum leak would make the tranny think it is near wide open. No leaks though...


Any other ideas?

I still suspect,Mal-adjusted TV Cable!!
Have you checked for Free Movement??(Sometimes the cable will start fraying inside cable Jacket and Stick a Little!!)
Have you checked the routing and made sure the Jacket isn't pinched or stretched tight somewhere??
Was the cable stretched accidentally during Engine Removal and Replacement??
Lets do some Checking, it's just like my "1957 24 ft Glass Magic Boat" with Twin 140 Johnson's,
She's just "KNOT QUITE RIGHT" Yet!!

 

[Rodney Gold]

Seems quite normal to me , why would you want the tranny to downshift as you slow? Engine braking?
My 400 and 350 wont downshift as my speed slows either.
IF you get high rpm upshifts at WOT , normal mid rpm upshifts when at normal non WOT throttle and speedy downshifts when you plant it , sounds like it's working properly.
You can always shift to 2nd manually if you want or build in a Hurst promatic type shifter to manually control all shift aspects.