904 slipping from 2nd-3rd (with video)

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MOPARCODY

MOPARCODY

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transmission has always had a 2nd-3rd. long story short i rebuilt the trans with the kevlar bands and new clutches throughout, transgo shift kit ect. everything seems to work great except it still slips from 2nd-3rd. im a loss and need some good racers advice on what i should do

car has a hughes 3500 stall and a stock mildly modified valve body

in this video you can clearly hear it slipping/slopping around

when racing someone i can feel the power loss and they creep on me until it shift and then i start pulling them again

[ame="http://www.youtube.com/watch?v=jrzGql7L5ms"]IMG 2638 - YouTube[/ame]
 
I like the red bands/clutches myself, but I switched from dexron III fluid to atf +3 in my 904, it would slip on the 1-2 shift. Went back to regular dex III and it shifted fine. I have no explanation for this. Is that front band adjusted? Also, you might have a shift overlap issue, It's kinda hard to hear it on the video. Is the tach flaring?
Love your car by the way!
 
66dartman said:
I like the red bands/clutches myself, but I switched from dexron III fluid to atf +3 in my 904, it would slip on the 1-2 shift. Went back to regular dex III and it shifted fine. I have no explanation for this. Is that front band adjusted? Also, you might have a shift overlap issue, It's kinda hard to hear it on the video. Is the tach flaring?
Love your car by the way!
Click to expand...

the tach doesnt jump up it just seems to flatline almost like the brakes are on

and thank you
 
What you have is flare in 3rd. Basically the kickdown band is releasing before the high gear clutch applies. This can be for several reasons. What rpm are you shifting into 3rd?
 
moper said:
What you have is flare in 3rd. Basically the kickdown band is releasing before the high gear clutch applies. This can be for several reasons. What rpm are you shifting into 3rd?
Click to expand...

6400 would a manual valve body fix this?
 
Did you upgrade the high gear clutch retainer? If you're using the factory one, with the single wound clutch return spring that could be part of your problem. No - it sounds to me like it's a mechanical problem - not a valve body problem. Did you isntall the bushing up into the case in the high gear apply port as part of the shift kit?
 
the single wound spring is in the front clutch pac...not the direct drum..

also what kick down lever ratio do you have in the trans?

i would use a manual valve body .....
 
You would have seen the price tag...lol. The Trans go shift kits usually spec a cupped plug that is drilled with a hole of about 1/8" diameter. they have it placed in the pressure feed to the high gear clutch. It's meant to delay the action of the clutch because the clutch applies faster than the band comes off... Sometimes it takes a little trial and error to get the right timing of the two events.
 
70aarcuda said:
the single wound spring is in the front clutch pac...not the direct drum..

also what kick down lever ratio do you have in the trans?

i would use a manual valve body .....
Click to expand...

i plan on buying one this week, probably the T/A cheeta

ill ask my trans builder about that spring
 
I'll add - the flare is not a good situation and there are also potentially major issues that can cause it... If your father's friend has a set of trans pressure gages you can check the pressures and see what's going on.
 
so i guess he can only check line pressure. how and what should i have pressure checked.

and will the tcs return spring solve my problem?

the fluid is clean and doesnt loose any
 
the single wound spring in the FRONT drum become unwound at high rpms..and let the front clutches drag....the 24 spring corrects this...

When is the last time you adjusted the kickdown band?
 
70aarcuda said:
the single wound spring in the FRONT drum become unwound at high rpms..and let the front clutches drag....the 24 spring corrects this...

When is the last time you adjusted the kickdown band?
Click to expand...

ahh ok

i dont know how to do this
 
Kickdown band adjustment is easy and in any service manual. I don't think it will do much, as the 1-2 shift is good by the video. But it should be done after the new trans has some miles on it anyway.
 
I had a flare problem on my 904. I double checked and triple checked everything. Tried 3 different valvebodies, rebuilt the front clutch 3 timed. A member here told me to take out the outer front servo spring. Works good now.

Sounds like you have an overlap problem, in 2 gears at the same time. It's common for a 904. My Trans Go TF-2 kit instructions said not to put the orifice plug in the case of a 904, and I didn't in mine. You have a shift timing problem, so maybe you need the plug. I would try the plug and see how it shifts. You can change the size of the hole to adjust you shifts.

If all else fails, you could always call Trans Go's tech line and see what they say. But make sure you have all the pressure information for the trans or they won't even talk to you. Don't ask me how I know this.
 
To support bobscuda and all who have helped, a excerpt from Tom Hand's article over at allpar:

"To refresh memories, I'll explain the 2-3 shift function again. When the Torqueflite shifts from 1st to 2nd, the kickdown band locks around the Front Clutch Retainer to stop the sun gear driving shell. To make the 2-3 shift, the kickdown band has to hold until the front clutch is applied and then it has to be quickly released. This timing is very important; too early of a band release causes the engine to "rev up" until the front clutch is applied. Too late of a band release and/or too early of a clutch apply is more common; this gives a "putting on the brakes sensation" which is actually called shift overlap (Since the rear clutch is applied in both 1st and 2nd, and nothing has to be released, kickdown band timing is not as critical in the 1-2 shift). Delay in the kickdown band-release and premature clutch-apply both cause overlap and, therefore, friction material wear."


Full article:

http://www.allpar.com/mopar/transmissions/torqueflite-tom-hand.html#axzz2GxyDJxOz

Hope this helps.
 
A&A transmission have been real great to work with for me. aandatrans.com
I have thier parts in my 904 including manual valve body and it has worked great for 6 years. Pulled it down for freshening and everything inside was great.
If you pull that trans out for repairs, make sure the clutch clearances are within spec and endplay as well. The return spring on the front clutch should be updated to the multi spring.
I would recommend a manual valve body for your application.
 
moper said:
You would have seen the price tag...lol. The Trans go shift kits usually spec a cupped plug that is drilled with a hole of about 1/8" diameter. they have it placed in the pressure feed to the high gear clutch. It's meant to delay the action of the clutch because the clutch applies faster than the band comes off... Sometimes it takes a little trial and error to get the right timing of the two events.
Click to expand...

my B&M shift kit had the same plug and it revved going into third and the manual recommended removing it if this occurred...removed it and the problem was solved
 
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