I had my transmission rebuilt 600-700miles ago and it has been great. Granted I only drive it few times a month, the rebuilt transmission has been awesome. As I was coming home the other day, I lost all forward gears. Even when I shift manually still nothing. It wasn't shifting hard, or anything abnormal. Just lost all gears at a stop sign that is at the end of my road. Luckily I was able to use my company vehicle to pull it out of the road.

So what would cause no forward gears, but reverse engages normal ? There is no abnormal noises, or anything out of the ordinary, Just no gears when I put it in 1st, 2nd, 3rd, or drive.

 

Since you have Reverse, the flexplate, converter, input shaft, input drum, output shaft and much more is working.
Now, assuming your really did try [D1] and still no forward motion:
Besides those, about the only thing all the forward gears have in common is the forward clutch inside the input drum. My best "guess" is that one of the teflon seals on the input shaft failed, causing a complete leak in the forward clutch circuit. There is also a forward accumulator in the valve body (VB), but I have not heard of that having a total failure. Personally I would check that accumulator first as removing the VB is easier than removing the trans, but I suspect the problem is further inside. Hopefully your rebuilder will warranty this.

 

Thanks. A really good friend of mine has a transmission shop and he did the rebuild. I bought all the parts, and he did the physical rebuilding (i kind of watched and was learning some). I have talked to him and we are going to tow it over to his shop, and tear it down this weekend and start checking stuff out.

I did try D1, and nothing at all. Not even the slightest movement. the rebuild did include replacing the plastic accumulators with aluminum ones. I was just curious if there was anything I could check before we towed it over this weekend.

 

No forward gears at all I would suspect something happened to the input sprag assembly. I say assembly because the sprag itself could not do that. We also had one not long ago that actually broke the tabs off that hold the forward clutch retaining ring was a first to see that.

 

Typically, even with a broken forward sprag the car will move in [D1] because the overrun clutches are applied in [D1]. However as Frank (Performabuilt) points out, a serious sprag failure could damage even the forward clutch. People usually report a "bang" when the sprag fails.
I'm sure the problem will be obvious when you open the trans.

 

Hmm. Ok. Ill tear it out this weekend and see what happened. There wasn't a bang or any noises which I would suspect some noise.

Edit. Do they make a heavy duty or upgraded part of it does turn out to be that ?

 

There is a Borg Warner brand sprag, which as far as I know, is the best available.

 

So got it all torn down and looks like the 3-4 boost spring packs some how got destroyed and destroyed the input drum. Luckily looks like the case is fine, and just the input drum took the damage. Pump was nice and clean when I tore it apart, and the case itself had no damage. I am going to spray it all down with some brake clean and flush it out.
I attached some pictures below --

 

Was the 3/4 clutch snap ring still in position?
I cannot see how the 3/4 load release springs would disintegrate on their own - I think someone above or below them failed.

That is a lot of debris in the trans; besides cleaning the entire trans internals, you really should disassemble the valve body (VB) too. One piece of metal could jam/clog something in the VB and ruin the trans.

Also, I think the converter needs to be sent away for opening and cleaning; you cannot just flush them. If you have an aftermarket cooler it needs to be replaced because it has parallel passages that cannot be reliably flushed. The stock cooler and cooling lines can be flushed.

I know that is a lot of extra time and money, but if you take shortcuts you might be back here sooner than you like.

 

Thanks for the input, really do appreciate it. There were 2 snap rings, the one above and the one below that were no longer in place. Some how the ridges where the snap rings sit broke all the ways around. The 2nd picture you can kind of see the broken ridges. As to how they failed, I do not know, or how both of them failed.

As for the converter, I am not sure what they cost to get torn down and cleaned but I do have another one that is the same thing (both are 2500 stall). I also have no clue who would clean it so replacing it with my other one sounds like a better choice. I have a spare 4l60e (came from a parts truck that friend was scraping) for parts so I may use that valve body. I plan on flushing the cooler lines and hopefully getting all the debris out, the aftermarket cooler I will replace.

 

Sounds like you have a good plan and fully understand the need to remove all trace of metal from the trans, valve body, converter and cooling lines.
Good luck.

 

So in this picture -

How do I remove those parts in the front of the case there ?

 

I don't work on these enough to recognize everything from pictures. So assuming snap ring for the low/reverse clutch return spring is out....
Apply air pressure to the rear most center hole in the case; it will blow the whole assembly out.

 

I couldn’t get the pic to come up. If removing to low and reverse piston, don’t forget to remove the 2 bolts that hold the parking paw guide on. If not removed the parking paw will keep the piston from coming out. Another thing I learned the hard way.

 

Havent had much time to tackle this project but I got a few hours after work today. I did get another case, input drum, and 3/4 drum to use. All are in good shape. Decided to look at the clutch packs that I pulled out of the transmission

I am no expert but clearly something got hot, now was it before the springs detonated or after I don't know.

I have a snap ring that goes in the front of the clutch packs in this picture - , but it seems to be too thick? It is just a hair too thick.

I ordered this rebuild kit - http://www.ebay.com/itm/261417249999...84.m1497.l2649 which I am using the steels and everything from it, but now I am stuck because of this snap ring.

 

Your images are not showing up. Did you make them public?
Therefore I don't know which snap ring you are referring to.
Explain which one and measure it with calipers.

Here are a bunch of GM part numbers for various snap rings. My dealer can get any of these within a few hours. (Granted, being near Detroit may help with speed.)

08663636 SnapRing for 3/4 Clutch
08647337 SnapRing for Low/Reverse spring cage
08642220 SnapRing for rear ring gear
08654141 SnapRing for front planet to output shaft
11500692 SnapRing for Overrun piston spring cage
24212462 Forward clutch apply plate
08647058 Forward clutch waved plate
24212468 Forward clutch backing plate
08642170 SnapRing for Forward clutch backing plate
08681553 SnapRing for Reaction Sun gear

 

hmm not sure why the photos arent showing up, they should be public since I don't have an account with them, its a free image hosting site.

thanks for the part numbers. It is the forward clutch backing plate snap ring but looks like its one standard size. I will have to remove the clutches and double check everything. I put 4 forward clutches in with the steels, and then the 2 overrun clutches below them which is how the instructions that came with the rebuild kit said to do it but the ring is extremely hard to get back into place.

 

Remember that every clutch needs to have clearance!
Including between the overrun clutch and the thick backing plate. And the forward clutch.
The overrun clutch starts with a steel, then friction, steel, friction and then the back plate.
The forward clutch starts with a waved plate, steel, friction,... ending with a friction and then the backing plate.
What year trans is the input drum from? I read that early years may have had a different spacing for the overrun and forward clutch.

 

The input drum is from a 2001 and my original is a 2000. Tried to keep them close to same years.

Ill double check the clutches after work but I am pretty sure I have it set that way. Is this snap ring usually hard to get in?

 

Your input drum is fine; just wanted to be sure it wasn't from a '93 or something like that.
That is a stiff snap ring, but should go in just fine. I recall something like .030 clearance for the forward clutch. I use what are called "horseshoe lock ring pliers" to install/remove these snap rings. I have a very nice but now discontinued Craftsman tool, but I see another company making one:

http://www.marlincrawler.com/hardwar...ap-ring-pliers

This tools from Amazon looks close:

The tool fits in between the snap ring and the inner edge of the drum.