I Hate My 904

-
Sounds like a good improvement but the 1-2 overlap is a problem that'll eat parts up fast. I see in an earlier post you mentioned the shop shimmed the rear servo. Did you check to see they actually did that? That's what I generally see cause 1-2 overlap. With the factory 2 spring setup on the rear servo the inner spring works against the outer spring slowing the release of the rear band and that's what creates the overlap. If your sure they shimmed it you might try backing off the front band adjustment a 1/4-1/2 turn to see if that helps by slowing down the application of the front band.
 
Hey Tracy,
When I installed the TF-2 kit in March, the rear servo had a shim in it that the shop installed. I took it out and installed the Trans Go spring.

I don't know if I mentioned that it has a 4.2 kickdown lever in it. How many turns should the kickdown band be set at? I was also told to set the rear band so it just moves back and forth a 1/4 of an inch away from the adjuster. It seemed kinda tight to me also.
 
Thank's Guitar. I readjusted the rear band to 3 1/2 turns, it was set at two.
I drove it afterwards and there was no change.

I think I've taken the pan off for the last time. Either I just let it go, it shifts perfect at cruise speeds, or I find someone that can fix it.
 
bobscuda67 said:
Hey Tracy,
When I installed the TF-2 kit in March, the rear servo had a shim in it that the shop installed. I took it out and installed the Trans Go spring.

You must be talking about the spring under the servo. I'm talking about the little spring within the servo. I attached a pic of the servo assy. You replace the spring called the "plug spring" with a spacer supplied by Trans-go. That usually eliminate 1-2 overlap.
Click to expand...

I don't know if I mentioned that it has a 4.2 kickdown lever in it. How many turns should the kickdown band be set at? I was also told to set the rear band so it just moves back and forth a 1/4 of an inch away from the adjuster. It seemed kinda tight to me also.
Click to expand...

I set the front band at 1/4" and I've tried different adjustments on the rear servo just to see how they react and find that 1/4" is plenty of space as long as the band is not out of round causing it to drag.

Torqueflite rear servo.jpg
 
Hey Guys, got to thinking. Could a leaking governor valve cause the 1-2 shift delay I have? I see Sonnax has a kit for sealing those valves. Has anyone ever changed those valves and how did it shift afterwards?

Correct me if I'm wrong, doesn't the rear servo pressure get released thru the governor valve? Maybe I need a valve that drains faster.

Looking thru my instructions for the TF-2 kit I see on the shift command feature that you have to grind on the governor valve. It must be to release fluid pressure. Just wondering if it works the same on upshifts.
 
bobscuda67 said:
Hey Guys, got to thinking. Could a leaking governor valve cause the 1-2 shift delay I have? I see Sonnax has a kit for sealing those valves. Has anyone ever changed those valves and how did it shift afterwards?

Sorry. Never had a problem with one so I'm not sure what problem it'd create. I will say I have used a couple Sonnax products and had problems with one. A rear servo. Was made way too small.
Click to expand...

Correct me if I'm wrong, doesn't the rear servo pressure get released thru the governor valve? Maybe I need a valve that drains faster.

Yes it does release through the governor plug. But I haven't actually studied the circuit to see exactly how it exhausts because I have never had an overlap problem with the rear servo inner spring removed and shimmed like I mentioned in my last post.
Click to expand...
.

Looking thru my instructions for the TF-2 kit I see on the shift command feature that you have to grind on the governor valve. It must be to release fluid pressure. Just wondering if it works the same on upshifts.
Click to expand...

I haven't done the shift command feature so I'm not sure.
 
bobscuda67 said:
Is there any way to test a valve body out of the car?
Click to expand...

Not that I know of. It would take something quite elaborate to fully test a valve body. Even then it wouldn't tell you some things because the clutch packs, band servo's, front pump, and governor affect overall performance.
 
Ok, It seems that the front servo pressure comes on to slowly on the 1-2 shift, causing the bamd to slip, then grab.
Could a leaking accumulator cause this? Or it's slow to fill? What else should I look for?
Fishy or Guitar, any ideas?
 
I'm not positive but I think if it was leaking bad enough to be slow activating the band it would never hold the band good. Just my thoughts on it. How can you tell the pressure is slow coming up?
 
I drove it last night after turning down the PR to flush with the retainer. I got on it a little and you could hear the band screech before it grabed. So I'm thinking it was applying slowly, I could be totaly wrong, but that's what it sounded like.
I took the valve body out tonight and might ask someone to try it in their car to see if it is indeed a valve body problem.
 
If you take out the valve body you can pressure test the front servo real easy to see if it's leaking. I've had quite a few bands slip and never heard one screech. Not saying it can't happen but I think it's unlikely it'd actually screech loud enough that you'd her it over the engine while you are getting down on it.

Guitar what do you think?
 
fishy68 said:
If you take out the valve body you can pressure test the front servo real easy to see if it's leaking. I've had quite a few bands slip and never heard one screech. Not saying it can't happen but I think it's unlikely it'd actually screech loud enough that you'd her it over the engine while you are getting down on it.

Guitar what do you think?
Click to expand...

That sure is what it sounded like. The noise could be the tires, but it sounded like it came from the trans. Thanks for helping me out.
 
bobscuda67 said:
That sure is what it sounded like. The noise could be the tires, but it sounded like it came from the trans. Thanks for helping me out.
Click to expand...

I understand. I think if it were the tires you'd be able to tell easy. I see Chris chimed in. If anybody can figure it out Chris will.
 
Update on the trans.
I talked to Chris Andrews on the phone and he thought I should put the accumulator blocker rod back in. It did help the 1-2 shift, but very little. I also noticed that after the fluid got hot, the 2-3 shift wasn't as crisp.
Chris has a auto valve body and billet rear servo for 300 dollars, but I think the TF-2 kit should be more than enough for a street only car. I hate throwing money at it. If I knew it would fix it then I wouldn't mind to much.

I got another totaly stock valve body to try, put it in and it was about the same as the TF-2 equipped valve body. Even with 4 turns on the Trans Go kit.
I noticed that the linkage for the TV valve cam doesn't touch the pushrod till the carb is at half throttle. Is that setup right? My 340 has magnum heads and I made my own bracket to keep the stock look. Maybe the ratio is wrong.

What to do;
Drive it with the old valve body.
Put the Tf-2 kit in the new valve body.
Buy Chris's setup.
 
I hate to drag up this old thread but I'm still having the same problem.
I drove it Sunday and it flares between the 1-2 / 2-3 shift.
I took it out of the car and removed the pump. There has got to be a parts mismatch between the pump, input shaft or direct drum. It's a single ring input shaft with 27 splines.
Do pumps come with different bore sizes to fit the input shaft rings, or are they all the same?
Is there anything in the tailshaft that could cause the flare,or maybe the converter?
I'm ready to give up on this trans and get another one.
 
bobscuda67 said:
I hate to drag up this old thread but I'm still having the same problem.
I drove it Sunday and it flares between the 1-2 / 2-3 shift.
I took it out of the car and removed the pump. There has got to be a parts mismatch between the pump, input shaft or direct drum. It's a single ring input shaft with 27 splines.
Do pumps come with different bore sizes to fit the input shaft rings, or are they all the same?
Is there anything in the tailshaft that could cause the flare,or maybe the converter?
I'm ready to give up on this trans and get another one.
Click to expand...

Bob there is nothing in the tail shaft area that'd cause it to flare up on shifts and the only way a converter would do that is if it were slipping very badly and if it were doing that it'd do it all the time, not just on shifts.

As for commenting on whether or not there was more than one bore size in regards to the front pump and carrier I can't say for sure since I haven't worked on many 904's but I've heard as long as the reaction shaft is the type designed for the carrier with 3 sealing rings they are the same size. What I'd do in your situation since you question it is to bench test the complete assy (pump, front and rear carriers). What I do is lightly clamp the pump upside down in a vise offset of center (to allow room for the input shaft to protrude) and using protective vise jaws or a thick rag to protect the reaction shaft splines and then I grease the reaction shaft sealing rings with trans. jel (vasoline works too) then slip the front and rear carrier together and flip them over and slide them down into place onto the pump. Basically how their assembled when in the trans. case. Then I inject air (30-40 psi) into the corresponding holes in the pump that lead to the clutch packs and listen for air leaks while checking to see if the clutch packs energize. When you inject the air make sure and hold the clutch packs in place as they will want to jump up and out of place if things are sealing properly. If you don't have a diagram showing what ports on the pump lead to what clutch pack let me know and I'll scan the picture from the service manual and post it.
 
bobscuda67 said:
I noticed that the linkage for the TV valve cam doesn't touch the pushrod till the carb is at half throttle. Is that setup right? My 340 has magnum heads and I made my own bracket to keep the stock look. Maybe the ratio is wrong.
Click to expand...

Bob I just noticed this last post you made on 6-18 and see you said you made your own bracket for the TV linkage and that it doesn't touch the pushrod until the carb is at half throttle. That doesn't sound right. It should contact it earlier. Where is the TV when the carb is at WOT? Should be pushed in all the way or very close to pushed in all the way.
 
fishy68 said:
Bob I just noticed this last post you made on 6-18 and see you said you made your own bracket for the TV linkage and that it doesn't touch the pushrod until the carb is at half throttle. That doesn't sound right. It should contact it earlier. Where is the TV when the carb is at WOT? Should be pushed in all the way or very close to pushed in all the way.
Click to expand...

The TV is pushed all the way to it's limit at full throttle. I even had it adjusted so that it would be bottomed out at half throttle, made no difference. I cranked up the pressure relief valve to it's max on a TF-2 kit. Still no differance.
I did air test it in June out of the case and in the case, but will try it again tomorrow.
Thanks for the help.
 
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.
 
You must log in or register to reply here.
-

Back
Top