I Hate My 904

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fishy68 said:
Bob I read back through the thread to refresh my memory and I keep thinking since you said it worked right before the shop did the valve body mods that it's something they did. You can try air pressure tests again since you have it apart but if there isn't a problem there I bet it's something in the valve body. Since the valve body is essentially the brain that makes things happen correctly one little mistake and it won't work right. May just have to find another valve body and try it.
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Well it started flaring up after they changed out the the clutch packs, input shaft, output shaft and the 274 gear set. When I took it out the second time is when I put the TF-2 kit and added the extra clutch disc, trying to fix the flaring problem.
I bought another valve body and tried it in it's stock form, still flared. I put the TF-2 kit in it and it still flared.
As far as I know the pump was never changed. That's why I was thinking it's a part mismatch.
 
bobscuda67 said:
Well it started flaring up after they changed out the the clutch packs, input shaft, output shaft and the 274 gear set. When I took it out the second time is when I put the TF-2 kit and added the extra clutch disc, trying to fix the flaring problem.
I bought another valve body and tried it in it's stock form, still flared. I put the TF-2 kit in it and it still flared.
As far as I know the pump was never changed. That's why I was thinking it's a part mismatch.
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Ok. I guess I mis-read it. That does sound more like a parts mis-match and I don't know 904's well enough to know interchangeability of parts. Maybe give Chris a call back and see if he has any other ideas.
 
Had a day off work today so I took the pump apart. The stator part number is 2538410. The 2 means the decade of the 1960's, and the 5 means the first year it was used, 1965. So my pump is the original to the 67 case, but my input shaft, foreward and direct drum are all 1968 and up pieces.
I looked up stators on the WIT transmission web site and they list 60-67, 68-78 and 78 and up nonlock up stators, so there must be a differance.

I will give Chris Andrews a call today and see what he thinks.
 
bobscuda67 said:
Had a day off work today so I took the pump apart. The stator part number is 2538410. The 2 means the decade of the 1960's, and the 5 means the first year it was used, 1965. So my pump is the original to the 67 case, but my input shaft, foreward and direct drum are all 1968 and up pieces.
I looked up stators on the WIT transmission web site and they list 60-67, 68-78 and 78 and up nonlock up stators, so there must be a differance.

I will give Chris Andrews a call today and see what he thinks.
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Let us know how it turns out.
 
Well, under further investigation of the pump and stator support, it's all the correct parts. The sealing rings are the correct diameter too.

Talked to some trans techs and it was suggested that the direct drum spring was a problem because it is wound the wrong way. Also that I should put in the restrictor that came with the Trans-Go TF-2 kit, the directions said to put it in for a 727, nothing about a 904, so I didn't install it. I guess it supposed to slow down the pressure on the direct drum 2-3 shift to stop the overlap. Anyone have any thoughts on if I should install it.

I bought a multi spring kit to replace the single wound stock spring. While waiting for it to arrive, I took the piston out of the direct yesterday and I found the small inner seal was rolled over from front to back, about an inch of it. It must have been like that for the year and a half I've been trying to get it to shift right.
What makes me really mad is when I brought it back the first time to the rebuilders, they said they checked all the seals. When I brought it back the second time I had them replace all the seals, which they didn't do, unless it rolled the second time too.
I'm going to take it someplace else and have the rings,seals and the bushings replaced again.
 
Glad you confirmed the pump parts. I can't say anything positively about the spring except I have seen them wound both ways in different transmissions and both transmissions worked fine. But the upgrade to a new piston and separate springs is a good one.

I don't have time to read back through the pages of this thread so I'm going by memory but wasn't the problem basically soft/mushy shifting? Soft/mushy shifting is not overlap. Overlap is when 2 gears are engaged at the same time momentarily and it's a rough jerky shift similar to stomping the brake momentarily right when the shift happens. The opposite is called runaway. That's when it shifts and either the engine spools up or the shift is just slow and sluggish. If that's the case installing the restrictor will only make that worse. Now you have found a seal that has had the lip rolled over. That's a MAJOR problem and might be the entire problem. Since your unsure about whether or not it should have the restrictor I'd call Trans-go and ask them. They are real sharp on torqueflites so I'm sure they would know.

Wise move finding a different trans. shop. Apparently the one you went to before isn't up to snuff.
 
Well I have another update.
I got my parts back and I had all the seals replaced, bushings and sealing rings replaced on the pump, front and rear drum too. Also replaced the front clutch piston.

When I got home I put the front drum on the pump and air tested it, it seemed ok. Then I filled up the high gear clutch drum with trans fluid and hit it with 60 psi of air and it bubbled everywhere. I gotta think that's not normal.

So now I'm thinking I need a new drum. This one refuses seal tight.
If I replace the high gear drum I might as well get a 5 disc drum. But is there going to be any fitment issues with the wider drum?
 
bobscuda67 said:
Well I have another update.
I got my parts back and I had all the seals replaced, bushings and sealing rings replaced on the pump, front and rear drum too. Also replaced the front clutch piston.

When I got home I put the front drum on the pump and air tested it, it seemed ok. Then I filled up the high gear clutch drum with trans fluid and hit it with 60 psi of air and it bubbled everywhere. I gotta think that's not normal.

So now I'm thinking I need a new drum. This one refuses seal tight.
If I replace the high gear drum I might as well get a 5 disc drum. But is there going to be any fitment issues with the wider drum?
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I generally only air test them at 30 psi. The lube I use on the seals doesn't always seal perfect when doing an air test but I've never had a problem after assembly. Wish I could help with the fitment question on the drums but I don't know 904's well enough.
 
Finally got time to work on the trans, been working 50 to 60hrs. a week and it makes it hard to work on it.
I replaced the inner and outer seals on the direct drum with the newer updated ones. It was really a tight fit so I think my drum was machined correctly. Replaced the single wound spring with a multi spring kit in the diect drum too. It air tested good, no air leaks.
I also installed a double seal accumulator to replace the stock one. I turned the PR valve two turns past flush on the valve body.

I got it all put back together and installed it in the car. I took it out today for a last cruise before winter. The trans shifts a whole bunch better. The 1-2 shift is almost to harsh and the 2-3 shift is quck and firm with no flare. I didn't have time to adjust the throttle rod yet but it shifts into second at 18 mph and 3rd comes at 32 mph. I might pull the valve body and turn down the PR valve to maybe one turn past flush next spring. Overall I'm happy with the way it shifts now, just took a long time to get there.

Now I can start building the 8 1/4 axle I bought off a member here this winter.
 
Good deal Bob. On the harsh 1-2 shift I have a question. Do you have a blocker rod under the accumulator? If you do remove the rod and install the stock spring. That'll ease up the 1-2 shift but not affect the 2-3 shift. Turning the PR adjustment 1 turn only changes the pressure about 3 lbs. so it's unlikely it'll do much for the 1-2 shift.
 
Hey Tracy, I did remove the spring and install the blocker rod a while ago, but it wasn't that harsh until I cranked up the pressure. Unless the stock accumulator was leaking.
I do have the TF-2 kit in the valve body and I remember reading somewhere that one turn equals 8psi.
Not a bad idea though putting the spring back in. I hate to mess with the pressure on the 2-3 shift since it's so nice. Something to try this coming spring.
I was thinkig if I backed off the throttle rod a little my shifts would be sooner and less harsh.

Thanks for all your help Tracy.
 
bobscuda67 said:
Hey Tracy, I did remove the spring and install the blocker rod a while ago, but it wasn't that harsh until I cranked up the pressure. Unless the stock accumulator was leaking.
I do have the TF-2 kit in the valve body and I remember reading somewhere that one turn equals 8psi.
Not a bad idea though putting the spring back in. I hate to mess with the pressure on the 2-3 shift since it's so nice. Something to try this coming spring.
I was thinkig if I backed off the throttle rod a little my shifts would be sooner and less harsh.

Thanks for all your help Tracy.
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I was going by the factory serv. manual that one turn equals 3 psi. May be different with the Trans-go kit since you change the PR spring. I haven't actually done any comparison checks myself. It may have been the stock accumulator was leaking and the combination of both installing a better accumulator and blocking it made a big difference. Backing off the throttle pressure will definitely help ease the shift some and make the shifts sooner as you said. It's worth a try since it's real easy.
 
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