Shiftless Tranny

[cash's90]

After driving in traffic for several miles today, my tranny decided to stop shifting normally under a normal load. From a dead stop, it would not shift from low to second below about 3500 rpms and required about the same rpms to shift from second to third. It refused to go into OD. I tried shifting manually and it refused to upshift until the higher rpms were reached.
The tranny was rebuilt about 3 months ago and had operated flawlessly except for two widely seperated times when it seemed to hang up during the low to second shift and required higher than normal rpms to shift The tranny then seemed to operate fine.
After the car sat for a half hour or so today, I drove it around the block and it worked just fine with no apparent shifting problems.
Any ideas as to what to check first would be appreciated.
The tranny shop is a hundred miles away so I'd like to solve the problem locally.

 

[86redMed]

Hi,

If I were you, I would call the tranny shop if the overhaul is guarantied.
Does it slips or just refuse to upshift ?

If it slips, it is perhaps a premature clutch failure or something like that. It can appears (more often on the 3-4 clutch) just a few miles (less than 100) after the overhaul. It is very easy to mis-asemble internal parts in a TH700. I have identified about 5 different versions of this gearbox (from years, from engine (V6, V8), even from car (Corvette, Camaro)) and the internal parts are sometimes not interchangeable...
The fact that even with the gearbox on low, there is no upshift, tends to show that if a clutch pack is burned, it is only the forward one.

If it just refuses to upshift, it could be a scratched governor gear (due to a bad overhaul) or a valve body failure (from the plate or its gaskets) too. Have you adjusted your Throttle Valve cable ? It is the first thing to look.


If the TV cable is good, I am afraid that only way to know it is to open the gearbox...

 

[Eagle85C4]

Your throttle valve is sticking. Mine does the same thing now and again. I have found that Lucas products has a tranny additive that works great.It is thick as molassas and red just like tranny fluid. Problem is that you have to remove the same amount as the bottle. I used a turkey baster with a piece of clear plastic hose to suck out fluid from the dip stick tube. Then used a funnel to pour the Lucas stuff in. Have the engine running when you pour the stuff in. Results are immediate. I have not had a problem since. The Lucas stuff really works great.

 

[cash's90]

Thank you for the suggestions. I drove the car this morning and had no problems. The tranny worked perfectly. I then adjusted the TV cable and drove it again this afternoon. Again, no problems. If the problem recurrs, I'll try the Lucas treatment.

 

[Pro Built]

To solve this "permanently", use the Trans-Go self cleaning non stick TV valve. It comes in all their Shift kits. These kits can solve other problems also.