I had some issues when my rebuilt 700r4, 2500 holeshot TC, and new gears were installed. The lock-up was too early. I wired a switch to the brake switch to that I can run under normal TC operation on the highway, but around town, I don't have to deal with early lock-up.

Now I'm starting to have tranny problems. I'll be at around 2500 (stall speed) and it feels like the car bogs. Now locked or unlocked, at 2500 I've got some good torque, but I get no acceleration. It's like the whole trans is just not wanting to turn. You know how when you try to accelerate on the highway, the car sometimes will bog for a sec if you're still in OD??? That's what if feels like, only it does it in every gear. I can't actually detect a problem at WOT, but the car feels sluggish. It only does this once it's warm, and it's getting worse.

First off, if anyone has a thought on the problem, by all means, do tell. But my original question is could I have damaged the converter wiring this way? I don't beat on the car much, but it still must be running a little warmer with the converter unlocked. I know some older trannies never locked, but then they weren't designed to either. Just hoping I didn't kill the tranny!!!

What shape is your fluid in?

I knew someone was gonna ask! ...I'm gonna check this morning. Last night was the first night that there was NO DOUBT that I had an issue and it was late, dark, and I was tired!

...I'll let you know.

Level and color are just right.

Without the TCC locked, slippage in the converter causes the fluid to heat up. Adding a higher that normal stall converter, especially a "slippery" one just makes it that much worse.

Yeah, but the TH350s and 400s don't lock. They can handle it.

How big of an auxilliary cooler are you running?

One thing to remember is that those trannies are 1:1 final gear (3rd), where as our 700R4's are 0.70:1 in 4th. Thus, they generate more heat.

Only runnin' the stock cooler.

As far as gear ratio, I only use the "off" switch in drive, so anytime 4th gear is used, the computer is operating the lock-up like normal.

I guess what I'm asking is not so much "could" there be a problem, because I already know there is. I know in this hobby that anything and everything can potentially cause a problem. What I want to know is, do you think it's LIKELY that my mod CAUSED a problem? I see some of you proffesional tranny guys post up quite often, and figured you all would have an opinion.

...if I diagnose a bad TC and buy a new one, I don't want to mess it up too, ya know? ...but I'm not that far yet.

I think your mod combined with the fact that you are not running an auxilliary cooler (required when you get a stall converter) may have fragged the converter. You can reprogram your PROM to alter TCC lockup parameters. I'd do that and install a nice big cooler for your next one.

The TH350 and TH400 aren't overdrives, and came from the factory with low stall converters. They'll overheat almost as easily behind a loose high stall converter.

Burn a PROM then.


That has nothing to do with it. If the cruise rpm is lower than the stall rpm, then constant slippage and excess heat happen.