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Discussion Starter #1
I have a 400 just put together, the core trans had a bad case and frt pump found another case and 895 pump.using hughes RPMV body and a direct drum from a 4l80 with good sprag.trans installed all forward gears wrk great but i need to bring rpm up to get it to go into reverse.at first once it was in reverse it felt fine but after 6 passes today reverse started acting up had to rev up arround 1500-1600rpm to get it to take reverse then it would back up fine.all forward gears good. The valve body came with new spring for pump, i did leave the center seal out of direct drum and the 2nd ring off center suport. there is not a core plug in the case in the reverse passage. all checkballs removed per instructions and removed the sealing rings off the rear servo accum piston. Any ideas on were i should start looking.Trans still in car. Thanks for reading and any suggestions.
 

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Was this a new build or a freshen? Was the v-body used on another trans previous?

It sounds more like a direct clutch problem than the rear band not working. Did you check the rear band clearance on assembly? Was a new rear band used?

What clearance was set on the direct clutch? Did you reuse the 4L80e aluminum piston in the direct or replace it with t-400 or steel piston?

If you call Hughes for tech assistance, talk to Pete or Jess
 

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Discussion Starter #3
This started with a trans that started to shift hard and then lost high gear.Removed trans boost valve was stuck,direct drum top plate broken between every locating tab. the 4l80 drum still has steel piston with non replacable seals.Set up with 5 friction and doubled up bottom steels to get .070 clearance. dont have tool for checking rear band, i removed sealing rings from acc piston put one on top of servo and could push servo caover to case with hand pressure. Did not replace rear band, this was replaced last time trans was done. Had to change case because cenrt support bolt was loose and elongated,and missing fretting spacer under center support. Valve body was on another trans beforee this. I did call hughes on fri after noon and all builders had left for the day.Thanks for help.
 

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Discussion Starter #4
Forgot to add that the trans was forward pattern manual shift w/engine braking,had no vac modulator or govoner, someone else set it up that way before me.
 

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There are some relined bands that have been on the low side of spec on the lining thickness .. that will cause the servo pin not apply the band properly.

I was thinking about the direct clutch pack since you made several passes and then reverse was worse.

From your description of the v-body install, that sounds right. No check balls used. Were there gaskets with the v-body plate?
 

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Discussion Starter #6
Yes the valve body has its own seperator plate and nice thick gaskets for both sides.Is the rear band only applied in reverse? I have a few books on th400 but no info on fluid paths with manual shift . Thanks ...
 

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If it is a forward manual , it should have 2 checkballs installed. Are you sure you are not reading instructions for a reverse manual valve body?


Hutch
 

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Discussion Starter #10
What is the pressure at in reverse? Good line rise? What sealing rings were used on the center support?
At idle 175psi in p-1-2-3 30psi in reverse. I used the sealing rings that were included in the ATI race overhaul kit. Thanks.
 

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Discussion Starter #11
If it is a forward manual , it should have 2 checkballs installed. Are you sure you are not reading instructions for a reverse manual valve body?


Hutch
Thanks for reading along, sorry to confuse you the trans now has a reverse pattern valve body. The old one was forward pattern,it was also set up with the direct drum center seal removed and the second ring on support removed with a plug in the oil feed hole on the shifter side of support bolt. The current set up still has seal out of drum and 2nd ring removed but no plug in case. Posted pressure reading above
 

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Discussion Starter #12
Pressure at 2000RPM 190in P-1-2-3- 125ish in Reverse.
 

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Thanks for reading along, sorry to confuse you the trans now has a reverse pattern valve body. The old one was forward pattern,it was also set up with the direct drum center seal removed and the second ring on support removed with a plug in the oil feed hole on the shifter side of support bolt. The current set up still has seal out of drum and 2nd ring removed but no plug in case. Posted pressure reading above

I must have misread it , sorry to add to the confusion. Oil pressure looks low in reverse. Does the servo air test well?


Hutch
 

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Pressure on main line in the reverse pattern Hughes valve body would be static, appears there is a leak some where in the reverse circuit
 

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Discussion Starter #16
I must have misread it , sorry to add to the confusion. Oil pressure looks low in reverse. Does the servo air test well?


Hutch
I am using a ATSG book and one by Ron Sessions for info,I have air tested the clutch pacs when I put them together,But I do not see info on where to aply air to check servo,do i need 2 remove V>B to do this? Thanks.
 

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Discussion Starter #17
Did you drive the car in 3rd to get the preassure reading or just sweep the shifter to 3rd?
I did not drive car had it on stands,checked @ 2000 RPM with brakes applied and without brakes,1st 2nd and thrid seemed to turn wheels fine didnt shift while they were turning stopped tires between shifting, reverse didnt seem to spin up at that rpm.thanks.
 

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Discussion Starter #19
Finaly got somr time to look at this.Droped valve body air checked the rear servo,first time i applied air it pushed fluid out the accumulator passage the next time it didnt do that,couldnt hear anything and it held air until i removed the blow gun from passage.looked at valve body gaskets and sep plate and the reverse passage is open,as stated before i do have center seal removed from direct drum and second ring off center support so i put a plug in the case and put valve body back on refilled with fliud same result 35 psi at idle in reverse and 120 at 2000. if brakes not applied tires will spin in reverse but if u hold brakes they will not.Forward gears still good. Thanks again.Im not gonna give up on this thing yet.
 
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