I've got an 88 w/ C6 and 5.8. I recently had a new long block put in and since then I've noticed trouble shifting from 2nd to 3rd. If I'm accelerating fairly rapidly it shifts fine but when I accelerate moderately or up a slight incline when it's time to shift from 2nd to 3rd it will shift up then down then up then down, etc. If I acclerate or let up on the gas it goes ahead and shifts although when I let off the gas and then try to accelerate moderately it will do it again.
I would appreciate any input anyone could offer.

Thanks,
Ron G.

 

I'm not really a c-6 guy, but I think they had bands...You may need to have them adjusted... I know my father had a 1987 F-150 with a 302 and a c-6 that had over 150k when he sold it in 1989. It was hard shifting aswell. I don't know how they adjust bands, but it may be simple, and you might consider cleaning the tranny and having new fluid put in, that may solve your problem...

 

If that C6 has a Vacuum Modulator on the side of it, you might look into that. A V-M is a vacuum motor that senses engine load (manifold vacuum) and translates it to mechanical motion. Years ago, these things usually went bad with age. Either the internal rubber diaphram sprung a leak and slurped AT fluid up to the manifold, or the diaphram became old and stiff (like people!), and didn't work so well anymore. The V-M's were relatively cheap $. Don't know if that's the problem, but if you are running out of ideas, could try it.
One more thing, if it has a V-M, check every inch of that long vac hose! Better yet, replace it with a good quality hose that can take the heat.

[This message has been edited by Granpa (edited 07-06-2000).]

 

Check the vacuum modulator and hose like Granpa says. See if there is proper vacuum to begin with. Check the adjustment of the kickdown lever.

------------------
2000 F-150 XL,RC,LB,5.4,4R70W,3.55LS,
Class III tow/Payload #3/Convenience pkgs.,
4-wheel disc/ABS,Chestnut/Parchment 40/60,
Ford bedliner & gas/wheel/spare locks,
3" cold air box modification,Superchip,
Dynomax ultra-flow welded 3" cat-back.