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Fresh 904 Sluggish "slipping" and soft 1-2 shift...

Posted By: Mapandjlp

Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/07/12 10:27 PM

I just put new clutches, steels, and bands in the 904 behind my warmed 360. I also installed a TCI Trans-Scat kit. It shifts through all the gears but seems to have a lot less power than before...seems like the trans is always "slipping". Also, the 1-2 shift is very soft no matter where the throttle is. Finally, it doesn't always downshift to 1st when slowing to a speed where it should downshift. I know it's tough to diagnose these issues without seeing them first hand but do you guys have any suggestions?
Posted By: MoparforLife

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/07/12 10:35 PM

KD linkage hooked up??
That is what governs the throttle pressure for proper shifting. If not hooked up and adjusted correctly the shifts will be soft and spungy. Also short transmission life.
Posted By: Mapandjlp

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/07/12 10:47 PM

Quote:

KD linkage hooked up??
That is what governs the throttle pressure for proper shifting. If not hooked up and adjusted correctly the shifts will be soft and spungy. Also short transmission life.



Sorry, should have mentioned that the throttle pressure linkage is hooked up and adjusted properly - lever is fully engaged at WOT.
Posted By: Erics5th

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/08/12 04:02 AM

Kinda sounds like you don't have enough line pressure (adjusted on the side of the valve body).
Posted By: calrobb2000

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/08/12 04:26 AM

hi
may be a bad seal ring on the input shaft ?
Posted By: Mapandjlp

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/08/12 12:45 PM

Quote:

Kinda sounds like you don't have enough line pressure (adjusted on the side of the valve body).



That's what I was thinking but I adjusted it (counterclockwise several turns actually) to the level that was suggested by the kit.

I did add an aftermarket trans cooler in line with the rad cooler. Could the extra length be causing a drop in pressure?
Posted By: JohnRR

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/08/12 02:04 PM

What does a TCI trans scat kit consist of ?
Posted By: Mapandjlp

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/08/12 06:13 PM

Quote:

What does a TCI trans scat kit consist of ?



For the 904, it was just a matter of enlarging a couple of holes in the seperator plate, drilling a hole in the valve body (basically joining two passages that weren't joined before), replacing the 1/2 shift governor, installing a smaller plug in the direct drum fluid passage, and cranking up the line pressure. Here's the install manual http://news.compperformance.com/Instructions/220000.pdf
Posted By: JohnRR

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/08/12 08:41 PM

Quote:



lever is fully engaged at WOT.



That doesn't always mean its adjusted correctly is this 1 piece or 3 piece linkage
Posted By: John_Kunkel

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/08/12 09:01 PM


Did you air check the trans prior to installing the VB?

If you're in doubt about the line pressure, hook up a test gauge and check it. If it's good, remove the VB and do an air check.
Posted By: Mapandjlp

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/08/12 09:04 PM

Quote:

Quote:



lever is fully engaged at WOT.



That doesn't always mean its adjusted correctly is this 1 piece or 3 piece linkage



It's one piece linkage. It all worked fine before I pulled it for the rebuild (other than the fact that the trans had 140k on it and needed a freshening).
Posted By: Mapandjlp

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/08/12 09:05 PM

Quote:


Did you air check the trans prior to installing the VB?

If you're in doubt about the line pressure, hook up a test gauge and check it. If it's good, remove the VB and do an air check.



Forgive my ignorance but what's an air check and how do I perform one?
Posted By: John_Kunkel

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/09/12 07:51 PM


With a rubber-tipped blow gun you introduce air into the various passages in the case to apply the bands/clutches and listen for big air leaks.

Attached picture 7198799-Air_tes.jpg
Posted By: Mapandjlp

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/10/12 01:19 PM

Quote:


With a rubber-tipped blow gun you introduce air into the various passages in the case to apply the bands/clutches and listen for big air leaks.



Thanks, John. The kit I used had me install a plug with a smaller hole in it into the front clutch apply passage in the case. Any idea what the purpose of this was?
Posted By: JohnRR

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/10/12 02:33 PM

Quote:

Quote:


With a rubber-tipped blow gun you introduce air into the various passages in the case to apply the bands/clutches and listen for big air leaks.



Thanks, John. The kit I used had me install a plug with a smaller hole in it into the front clutch apply passage in the case. Any idea what the purpose of this was?



Not the john you questioned , but that plug is to slow the apply of the front clutch due to the increase in line pressure making it happen faster without it . It would not cause the sluggish feel or cause your soft 1-2 shift.
Posted By: Mapandjlp

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/11/12 12:12 AM

I spoke with Mr. John Cope of Cope Racing Transmissions today. We discussed several different scenarios and based on our conversation, I decided to pull the valve body and have a look at where I had the line pressure adjustment set. According to the TCI Trans-Scat kit I used, the distance between the spring plate and the valve body was to be 1 3/8". I used this as my guide. According to Mr. Cope, the maximum should be six turns from the point where the spring plate is flush with the bracket. Mr. Cope told me that you can actually have too much pressure on the valve causing the opposite effect.

I adjusted the plate according to the advice from John Cope. I also re-adjusted the low/reverse band. These two changes seem to have fixed my problem.

Thanks to all of you who helped!
Posted By: JohnRR

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/11/12 12:35 AM

Quote:

I spoke with Mr. John Cope of Cope Racing Transmissions today. We discussed several different scenarios and based on our conversation, I decided to pull the valve body and have a look at where I had the line pressure adjustment set. According to the TCI Trans-Scat kit I used, the distance between the spring plate and the valve body was to be 1 3/8". I used this as my guide. According to Mr. Cope, the maximum should be six turns from the point where the spring plate is flush with the bracket. Mr. Cope told me that you can actually have too much pressure on the valve causing the opposite effect.

I adjusted the plate according to the advice from John Cope. I also re-adjusted the low/reverse band. These two changes seem to have fixed my problem.

Thanks to all of you who helped!



Did you readjust the FRONT band ? the low reverse band is only used in reverse and when you have the trans shifted into L ... low, it is not applied if the trans is in D ...drive.
Posted By: Mapandjlp

Re: Fresh 904 Sluggish "slipping" and soft 1-2 shift... - 05/11/12 12:51 PM

Quote:

Did you readjust the FRONT band ? the low reverse band is only used in reverse and when you have the trans shifted into L ... low, it is not applied if the trans is in D ...drive.



Yep, that's the first thing I did when I knew it wasn't acting quite right.
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