Diy th400 with ck rmvb no reverse

[asloan5]

this is my first trans build
when I put car in 1 2 or 3 it wants to go foward, reverse is like neutral..... not a detent issue as same problem is with shifting by hand into reverse
trans is a follows alto power pack kit every bushing is new every thrust washer and bearing is new all new pump gears new ptc convertor 34 element roller clutch all new borg warner bands I followed tips from the th400 thread as far as th350 pump bearing in rear of case restricted pump feed to save crank thrust bearing
also the 1 bolt hole on the valve body spacer plate does have the bolt in it
what else to look for ?

 

[asloan5]

trans line pressure is 180 lbs average in all gears p r n 1 2 3 shifting from part to reverse, neutral to 1 and 1 to 2 I get a split second drop in line pressure to about 100 lbs
I inspected the accumulator piston and the rings are removed per the ck rmvb instructions, the bore the piston fits into looks good the seal on the piston looks good no cuts (it's new) and by hand I can push the piston into the bore. The cup on the reverse band is where it's supposed to be and the cover and gasket are reinstalled. note I have to push the piston just to get the seal portion to the secondary bore when I let off 1 side of the piston is almost flush with the case <-- is that correct or is the spring too large ? I reassembled these parts and reinstall the valve body. I pushed the transbrake selonoid in and let it pop everything there seems to move fine. And after all this same NO REVERSE ! with these extra details anyone have an idea ?

 

[turbobitt]

Having a CK valve body in mine, This would be my guess. Did you install the cupped plug into the direct feed passage ? His VB doesn't use any check balls and the passages are straight forward.

 

[turbobitt]

This is the instruction for this step.

 

[turbobitt]

There is another possibility. CK's VB rerouts oil in reverse and forces a valve to stroke so that oil doesn't leak out the manual valve while in reverse. I am only going by memory so I'm not completly possitive. If you remove the VB, check the only spring loaded valve for free operation.
Allan G.

 

[asloan5]

This is the instruction for this step.

that page is not in my instructions from ck and I did not do that step because my paperwork had nothing about it. Chris did I get a partial instruction packet or is the valve body I bough this past month a newer design ?

And Allan G. thankyou

 

[chris718]

We have updated and that plug out wont cause that issue.follow my instructions in the other post.Iam not going to be around to answer qs today,am on the way to church.If you call in tomorrow I will try to help you find where your problem lies.

 

[asloan5]

further testing the transbrake wire up has no effect on my no reverse.
with the car on stands at 1000 rpm in 1st 2nd and 3rd the speedometer is reading the same 20 mph does this help define the problem ?

 

[turbobitt]

What year transmission did you start with ? Can you tell us anything else about the internal parts ? Is the drum in the back have a roller clutch or a sprag ? I'm just throwing this out because the older drums(the one the low-reverse band wraps around) can have a sprag and I think it can be installed backwards. I don't know what effect that would have.
Since you don't have reverse, this would imply that the direct drum and/or the low-reverse band are not engaging. Have you tried air checking these by applying compressed air into the ports with the VB removed ?
Allan G.

 

[asloan5]

What year transmission did you start with ? Can you tell us anything else about the internal parts ? Is the drum in the back have a roller clutch or a sprag ? I'm just throwing this out because the older drums(the one the low-reverse band wraps around) can have a sprag and I think it can be installed backwards. I don't know what effect that would have.
Since you don't have reverse, this would imply that the direct drum and/or the low-reverse band are not engaging. Have you tried air checking these by applying compressed air into the ports with the VB removed ?
Allan G.

It's a 6 bolt pump unsure of year. I bought it from local salvage yard. It has a turboaction sticker on it. when taken apart it had a cheeta vb plate/ shift kit and 34 element roller clutch I have not tried the compressed air but that is next

 

[jakeshoe]

What year transmission did you start with ? Can you tell us anything else about the internal parts ? Is the drum in the back have a roller clutch or a sprag ? I'm just throwing this out because the older drums(the one the low-reverse band wraps around) can have a sprag and I think it can be installed backwards. I don't know what effect that would have.
Since you don't have reverse, this would imply that the direct drum and/or the low-reverse band are not engaging. Have you tried air checking these by applying compressed air into the ports with the VB removed ?
Allan G.

The early TH400s used the sprag type element for low. If you install it backwards you will have reverse, but it will lock up in 1st. That part is called the reaction carrier or front planet.

Air check the directs, but if you have 3rd, you are OK on the directs.

My guess is you have a low servo pin length issue. Too short.

Remove the low servo, remove the accumulator piston and spring, remove the servo seal, and remove the piston return spring from the pin.

Re-assemble the piston on the pin (with the small washer). No seals, no springs.
Install it in the case bore, and compress the rear band. See what you have, if it goes very deep in the bore at all, use a longer pin or weld up the tip.

 

[asloan5]

The trans was previously a turboaction built trans with a cheetah valve body during the orig build they put a small plug in the reverse oil passage. I removed it reinstalled valve body and it now kicks ass. Thank you all for the help.