47re sluggish to engage and disengage drive

[Cummins Driver]

Hey guys, built my own transmission and have put a little over 1000 miles on it so far. It had been working great. Yesterday we did a 220 mile round trip towing about 4000 pounds with no issues. However, when I got home I was backing the trailer in and had to put it back in drive. I noticed it was kind of sluggish engaging into drive. So I messed with it some today. It is sluggish going into drive, but it also doesn't always come out of drive like it should either. Sometimes when you go to neutral it is still like it wants to pull forward. It had been working perfect up until now. Reverse always engages like it should when you come from park. Sometime when going from park to drive you have to blip the throttle a little and it will clunk into gear. Every so often it still works like it should. Going down to manual 2 or 1 seems to not really make a difference in getting it to engage.

This morning it was pretty slow to engage drive. It still drives perfect once it engages. I had to run over and move a tractor for dad so I hauled about 11k pounds with it and no issues at all. Holds all the gears fine, fluid is still bright red and not burnt.

Anyone have any ideas? Transmission has a Goerend Rebuild kit in it with a Transgo Shift Kit and DPC reman single converter. Thanks for any help

 

[Cummins Driver]

Nobody has any ideas? Ill probably pull the pan off tomorrow and have a look. Not sure where ill go from there.

 

[Cummins Driver]

Well per Goerends advice I pulled the trans back out and dug into the rear (forward) clutch assembly. Clutches seemed to look fine. I pulled the apply piston for the rear clutch and found this nick about the width of a small sized flathead screwdriver on the inner lip seal. Any thoughts on if this is actually my issue? I air tested the rear clutch before pulling the trans and it basically just hissed. Didn't sound like it was applying anything. When I air tested the direct clutch just for reference I got a solid clunk like I expected.

All I can figure is that because of the nick the inner lip seal is slow to seal up enough to build pressure to engage the clutches when put into drive. Then when taken out of drive in thinking its slightly rolling down or binding as the piston tries to travel back the other direction.

Probably going to replace this, reinstall everything inspecting good as I go, and air test before reinstalling.

 

[Big Blue24]

Your piston could be over-extending, how much clearance is in that clutch pack, is the belleville spring new? Looking at the seal, it looks suspicious but not quite bad enough to make me think that's the only problem, check everything over carefully, especially the input shaft hub, belleville spring cushion spacer and snap ring stackup/orientation, input shaft lowest steel sealing ring, stator support bushing on the pump, pump itself, plugs on the pump passages, VB detents and manual valve position relative to detents.

 

[Cummins Driver]

Thanks for the response. I was a little rushed looking at it last night and I had mainly focused my attention on the rear clutch piston because I was thinking my problem would be in that area. I got a new inner lip seal today but i was also having a hard time believing that would be the only issue. I wanted to spend some more time looking everything over better when I got home today and I found what I believe to be the real issue.

Basically, I was looking at the input shaft to inspect the seals and I found the bushing out of the rear of the stator had come out and was still on the input shaft where it would normally ride. It had obviously spun in the stator at least a little bit, and it also has slightly grooved my billet input where the bushing rides. The bushing is grooved some on both sides but not terrible. The lower teflon sealing ring on the input shaft was also a little damaged and stuck in its bore. The upper teflon ring was still fine and moves freely. Im guessing the bushing spun, got the input shaft a little warm and stuck that teflon ring which allowed it to leak pressure through and out the back of the bushing? Im still not sure why the bushing put grooves in the shaft. Its like it was maybe too tight on the shaft to begin with? Im not sure. The stator bore where the bushing fits into seems to still be in pretty decent shape.

First off, any ideas why this would have happened? I dont remember having any issues installing that bushing. Is there something I can do different to ensure this doesn't happen again? Second, what do you guys think about re-using this shaft with the small grooves where the bushing rides now? If it was a stocker it wouldnt be a big deal, but thats a $650 shaft...

 

[Tobin]

Is that a stock pump or aftermarket replacement?

 

[Cummins Driver]

Its the original pump as far as I know. Dont think the trans had ever been into until I bought the truck

 

[Tobin]

I've seen issues with aftermaket pump parts. Not that specifically, but I would get new parts from a stock trans or Goerend.

 

[Big Blue24]

The shaft looks like it will be fine, just clean it up a little with fine sand paper or some emery paper from the plumbing section at the hardware store. Use a foot long piece and polish out the roughest grooves, if you have access to a lathe or something big enough to spin the shaft, it will be even faster to clean up.

I'd replace the "green" teflon seal with a metal seal from your rebuild kit, it should be white painted. If the lowest torlon nude-colored seal does not spin freely, it probably needs to be replaced and the input shaft groove needs to be cleaned up/deburred.

If you decide to reuse your pump stator, use green loctite when installing the new bushing and be sure to hone it a little if it's tight on the input shaft. This is a moderately common problem with billet input shafts and pump stator support bushing spinning if you don't check the clearance... this is something not listed or noted for inspection in ATSG manual but something "good" builders check when building the transmission. I didn't learn to check this till I had my first pump stator bushing failure, with similar results to what you're having. Mine didn't show it's face till after 10 months of street use and was compounded by a slightly out of spec high-runout billet input shaft. Lessons like this only make you better at building these things... so keep your chin up and move forward!

 

[Cummins Driver]

Awesome, thanks for the info. It at least makes me feel like I didn't do anything to mess it up. Like you said, the manual has no mention of this so its kind of hard to know to check it.

Im going to check the stator out a little better and see if its still useable. I havent really looked hard at it yet. I dont think its too bad but considering a used one isnt real high, I may find one with no damage, put some green loctite on it, make sure everything fits good and roll with it. I do think my shaft will be fine with a little cleaning up.

Are the metal seals better than the teflon? I guess these were teflon, kind of feel like plastic. I believe my transgo kit came with these two seals for the input shaft but im not sure what they're made of because i didnt pay them much attention.

What is the best way to check fitment of the bushing/input shaft? Mic the shaft and the bushing and allow for a certain amount? I thought about getting a new bushing and having the shaft machined to fit instead of honing the bushing, plus that would help to clean up the shaft. What are your thoughts?

I was bummed about the issue, but just knowing it was a simple mistake, and something the manual doesn't even mention, makes me a feel a little better. Luckily it didnt hurt anything else, so I should be able to get it back together without a whole lot of cost. I dont have to drive the truck everyday either so im not in a bind, just one of those deals where I hated to have to pull it back out more than anything.

 

[Cummins Driver]

Well I've got my new sealing rings and bushing. It seems like it could be a little too loose on the input shaft though. Im not sure what the specs are supposed to be on clearance there but I can actually rock it slightly side to side. Im going to slide it on my stock input shaft and see how it fits that. Im also not sure if it may tighten up a little when I get it pressed into the stator. Hoping It will work out because I would like to get it back together before next weekend.