Okay I've got a 1978 Pace Car with 93k miles, 350, with a TH350 Transmission and am having problems.  Was wondering if anyone could give me an idea whats going on. 

I was leaving a gas station and the transmission slipped really bad twice.  I initially let off the gas and slowed down and it seemed normal.  But as I sped up again and the transmission shifted from 2nd to 3rd it lost all power.  The engine would rev-up but there was no power to the transmission. 

I stopped and checked the fluid and to let it cool down.  The fluid is at normal level, looks normal, and doesn't seem to have any oder like being burnt or anything.  After sitting for awhile I tried a lap around the parking lot and the car ran fine until I got up speed for it to shift into 3rd and then lost it lost all power again   The car runs fine in 2nd and I drove it home 20 miles at 35mph in 2nd.

Any ideas what going on?  Thanks.

cilrah38593.7785069444

I'd say torque converter, but I'm not an automatic tranmission expert.

Mark

It ain't gots no thard gear!

First question: Does reverse work OK? No slip/shudder?
Third gear & rev. use the same clutches, so if the problem is in the direct clutch pack, it will also have a rev. problem, whether it is a slip, or a "delay", meaning it takes a few seconds to engage rev. after you move the shifter.

If rev. works well, then it could be a problem in the valve-body, but not likely, if it feels like the trans went to "neutral" instead of third. If the shift valve hangs, it would just stay in 2nd, and not "neutralize", which is what it seems you are describing.

It could also actually be shifting back into 1st gear, instead of 3rd. This would feel like a 'neutralize', but it's not. Its just that 1st gear at 30-35mph is basicaly an "over-run" condition. If you give it more gas the car would still move, but it would be the same as driving it in 1st at that speed.(I know, its confusing, but I'm not good at 'splaining this stuff; I don't have the skill to teach ). The governor gear being damaged would cause this.

The governor is on the driver-side, rear of the trans, just ahead of the tailhousing. It has a large, round cover over it, sometimes with a clip, to hold the cover on. If you take the clip off, take a medium size screwdriver, and a hammer, and knock the cover off. Fluid will come out, so be prepared for that. Then grab the gov., and twist it out. The gear on the end of it requires that it be twisted, as it meshes with the gear on the output shaft of the trans. On the end of the gov., there is a nylon gear, with a roll-pin thru it. Look at the gear. If it is damaged, it will be obvious, as it will be either "apple-cored", or have a tooth or two missing/damaged. Apple-coring is when the center of the gear is worn down, and it looks like an apple core looks after you've eaten the rest of the apple.

If you find the gov. gear is damaged, you can either take it to your local trans shop and have them replace it, or try to buy one from them, and replace it yourself. To replace the gear, first knock the roll-pin out with a small drift-punch(or nail if you wish). Then just pull the gear off. Push the new gear all the way back into the gov., making sure it is bottomed out. Then you have to drill the hole thru the nylon gear to re-install the rollpin.(Make sure, if you do this, to get a gov. gear for a 350, and not for a 700. They are almost exactly the same, but they are not interchangable. If you get the wrong one, you'll be doing this again in a few miles!)

To reinstall, just twist the gov. back into the trans, making sure it goes all the way in. Then put the cover back on, with a new "square" o-ring, and tap it all the way back on with the hammer/screwdriver. Then reinstall the clip, if it has one, check the fluid, and give it a go.

Now, the bad news..... If the gov. gear is not the problem, you'll need to have the trans pulled & rebuilt.

I hope this mumbo-jumbo makes some sense, and you can fix the prob. with the gov. repair.

btw... if you need a gov. gear, and you're not in a hurry, holler at me, & I'll stick one in the mail to ya. You should be able to buy one at the trans shop for $5-$10, max. I'll send you one free, if you gots the time to wait for USPS.Adams' Apple38593.8397685185

bummer, sorry to hear that.  remember that shop in Lacey, he might be able to give you an idea too.

Only trouble I had coming home was fitting all the crap into the vette that the wife won, bought, and/or stole.

and then there is the wiper door monster, are you guys sure that the 1970 corvette convertible with the LT-1 engine do not come with the option that thw wiper door opens and closes when you start the engine?

[QUOTE=Adams' Apple]If rev. works well, then it could be a problem in the valve-body, but not likely, if it feels like the trans went to "neutral" instead of third. If the shift valve hangs, it would just stay in 2nd, and not "neutralize", which is what it seems you are describing.
.[/QUOTE] Wow Joel you described this to a tea. Exactly, it feels like the trans go from 2nd to neutral   I know its not shifting back to 1st cause its got less power then 1st ever had when this happens.  cilrah38593.9468865741

Tell ya this, theres an extreme wealth of knowledge here and its appriciated! 

Okay this evening I took the Vette out for a drive around the neighborhood with the engine and transmission totally cooled down, it was extremely hot when I had my first problems.

I take off and the car runs great until it shifts into 3rd, then it looses all power like going in neutral.  I did step on the gas a bit and it shifted into 3rd after a few seconds but then lost all power again after about 4 seconds

Good news is, this will all be covered under the extended warrenty I purchased when I bought the Vette. I only have to pay a $100 deductable

cilrah38595.8014699074

I'd still recommend checking the governor gear. (Thas my story, an I'm stickin wid it!)


Wow, looks like we both posted about the same time! It's good that you got the ext. war. on the car, but why shell out $100 for a 20 minute, $5 fix? (Just tryin' ta help!) Adams' Apple38595.8051157407

I've devolped a problem with my 78 trany too, but fit's Adam's 1st description well (not going into 3rd, and Rev having a short delay going in).  After checking the fluid, it was very low (I know, shame on me!), and still have to hit the local store for more.  Now, I'm an idiot when it comes to transmissions, but from what Adam said, should I assume that I'm going to have to make my way over to a transmission place, or is it possible that replacing the fluid would temporarily solve the problem (until I take on finding why the fluid's gone)? 

This problem was non-existant until I had the front end of the vette on a jack for a few weeks - Hurricane Wilma dented my schedule replacing the fuel pump.  When the pump was fixed, and my vette back on the ground, the problem was there.  Don't know if being at an angle for a few weeks made the difference or not, but figured I'd throw it in.

Dave, if your trans was low on fluid, but no obvious leaks on the ground, check the modulator. It is the round "can" looking thing on the pass. side, rear of the trans, with a vaccuum hose on it.

Pull the hose off. If any trans fluid runs out of the hose, or the end of the mod., then the mod. diaphragm is ruptured. This will allow trans fluid to be sucked up into the engine(intake), and will be burned in the cylinder. That is why you never see a leak, but the trans is low on fluid a lot. If it is leaking, replace the mod. first, and see if it helps with the other problems(3rd & rev).

It is possible, if the trans has been run low on fluid very much, the high(3rd) gear clutched are burned. 3rd gear in the trans takes a lot of fluid, volume-wise, so if its low, 3rd is usually the first thing to be damaged. Since 3rd & rev. uses the same clutch-pack, if there's a problem in one, you'll normally see a problem in the other.

Check the mod. first, and see what you find.

btw....... I wouldn't recommend changing the fluid on any unit that has a "delay" issue. You could very well make the problem worse. The best thing to do in that situation,(I know a lot of folks will shake their heads), is drain the fluid, change the filter and pan gasket, and put the old fluid back in it. The reason for this is, new fluid has a high detergent content. Putting it in a unit that is marginal will wash even more crap out of all the nooks & crannies it has been hiding/stuck in, eventually finding its way thru the filter, and into all the nice, finely machined valves, and sticking them.