Transmission gurus!

blackmega3500

blackmega3500

New member
Joined
Jun 24, 2011
Messages
4,553
Units a comp68 that's started acting insane lately and is having issues off and on about temp sensor intermittent, 2c solenoid circuit issue, will randomly go to 4th after decelerating and coming to a stop. Turn it off and back to normal, til eventually happens again. Starting to be come more frequent and oddly flashes that the temps 400* (read off the scout monitor which reads ecm) prior to startup, and on a few occasions has even flashed 1022* then disappears!

Screenshot_20170527-230427.png


Now I know those are electrical and all, but the one that's got me not feeling so hot is this that was found in the pan today after dropping pan for inspection and to check filters since pressure feels off on some shifts and torque converter had delay the other day. It looks to be maybe pieces of a grenaded spring.

20170527_222710_001.jpg


Trans shift into all gears just fine, 3-4 feels extra soft though.

Any place is a good place to start, thinking time for a rebuild anyways!
 
Last edited:
Yep I bet the snap ring failed on the 4th clutch pack and let the return springs dump out and get chewed up I have seen the whole limp break off the center support and cause that also,Transmisson needs to be tore down for sure you have a major issue.
 
04.5ROHLING said:
Yep I bet the snap ring failed on the 4th clutch pack and let the return springs dump out and get chewed up I have seen the whole limp break off the center support and cause that also,Transmisson needs to be tore down for sure you have a major issue.
Click to expand...

It still has 3-4 engagement as usual, feels that the pressure is down for sure. Flawlessly goes into 5 and 6 and makes full lock on both.

I'm wondering if the broken spring is from the valve body and causing pressure issues!
 
It would be pretty tough for a spring to remove itself from a bore in the valvebody. Not impossible, but I tend to agree with the above diagnoses.

Don't think there are any external valvebody springs.
 
Red Sleeper said:
It would be pretty tough for a spring to remove itself from a bore in the valvebody. Not impossible, but I tend to agree with the above diagnoses.

Don't think there are any external valvebody springs.
Click to expand...

I've read where the TCC spring is a known wear out item in the rfe transmissions, and can result in drain back and stall speed issues.

I've noticed that off the jump power has felt sluggish for some time, but was thinking more of a rail psi issue.... til the other day when shifting from 1-2 was so delayed it felt as if I was about to go into the dash.

Side note, fluid looked great and normal glitter look to it. No flakes or chunks besides the tiny spring!

There's definitely something at low rpms bleeding off pressure!
 
Last edited:
Also notice how the system when it goes to limp it displays 4th on dash, and 1st on digital read from ecm!
20170528_115911.jpg
 
I'm thinking it's one of these from the pump!

Notice it says "this spring is known to break".

This was pulled from the ATSG 68rfe service manual!

20170528_150941_001.jpg
 
Wow. ATSG addresses that the spring is common to break? Guess it's a problem none the less.

Does a TransGo shift kit address this issue?

I remember on my 48re there was something to replace in the pump if you had the transmission removed from vehicle.
 
What a day!

Started off by pulling the valve body as recommended by member on CF looking for shrapnel. All checked out and looked good at first no metal on top.....
20170531_160532.jpg

E5076115-_1496268405417.jpg


but the C2 and C4 seals are shot! This definitely caused my line pressure issues since it was just bleeding off at high psi which I have set to max at 200psi.
20170531_160742.jpg


Still left not sure what happens since I didn't see debris, I went for a closer look underneath the assembly at first all looks good...
311C31C5-.jpg


Then bam like a wooden spoon swung at me by mama the little bastard showed it's ugly face!

3E51DBE0-.jpg


The snap ring has left the building!

It now has slight play in the steels, but trucks definitely getting a new build.

The current build actually had the old style retainer, but it's getting all the newest updates when I drive to Florida to get it fixed!

I've got to say, I'm pretty damn impressed with this Suncoast build holding where my setups at in the mid 800hp range that even with the seals wearing like they had over time, and the fluke thing of the snap ring popping it's a solid solid work of art and moves my 12,500lb MEGA Long bed dually with ease!

It honestly was time for a refresh anyways, just an excuse for a vacation now!
 
That snap ring is supposed to be there that's not the problem air check the trans while the VB is out and listen and see if the clutch packs are returning when you let the air off I still believe the springs you seen are 4c return springs
 
04.5ROHLING said:
That snap ring is supposed to be there that's not the problem air check the trans while the VB is out and listen and see if the clutch packs are returning when you let the air off I still believe the springs you seen are 4c return springs
Click to expand...

Sayyyy what?! What snap would that be then? Air check.... ? Would you expect there to be more than one spring at this point?
Found this... https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.atsg.us/atsg/skin/frontend/default/atsg/images/air-check-demo.pdf&ved=0ahUKEwih94a-pZ7UAhWDMSYKHbckBBkQFggcMAA&usg=AFQjCNFooBBRSduKRRlGBijHVu_VxJi4Rw
Also did you see the valve body bores?
 
Last edited:
Today I went to drive it up over a curb and could hear what sounded to we a shudder aswell...
 
'Air Check' - as in supply shop air to the ports to see if you can get the clutch packs to actuate via air pressure instead of oil pressure.
 
CorneliusRox said:
'Air Check' - as in supply shop air to the ports to see if you can get the clutch packs to actuate via air pressure instead of oil pressure.
Click to expand...

Yeah I got that, and edited the post shortly after posting that. Link has diagram of of 4c clutch orifice.

Recommended psi? Saw somewhere that said 30psi is enough, but wanting to be sure!
 
Last edited:
Green2015 said:
68 rfe is the main issue. Ditch that and problem solved
Click to expand...

Honestly 68rfe is a fantastic trans when built and this build has 4 years on it so it's performed solid at all times! Enough to blow through my commercial treaded duals in around 30k. Both solid work/play unit and I'd never go away from it.
 
Yeah good to about 800hp but none are really living over that range. Who wants to replace clutches every year ? If it was that bullet proof people wouldn't be swapping at the same cost sun coast or revmax sells the comp units for that's only rated to 800hp vs a 1,500 hp rating for the same price on a 48 installed
 
You can see here the cut outs for the O-ring, in addition to the added carnage from when I bolted up the valve body on last evaluation.

I also inspected for any new signs of any metal or spring and nothing was found.
20170606_142329.jpg
20170606_142132.jpg


20170606_142334.jpg


I went ahead and performed the air check and no massive air leaks were noticed and 2C and 4C both held 30psi and you can hear 4 engage with pressure.

https://www.youtube.com/watch?v=J3HzXr9rkrg

Went ahead and replaced seals on billet pieces(have oem ones ready for a backup), torqued unit all around to 110in lbs and refilled.

Noticeably better and now its acting normal. Now I plan on seeing what the CVIs are soon, and then allowing the trans to do an adaptive relearn.
 
Green2015 said:
Yeah good to about 800hp but none are really living over that range. Who wants to replace clutches every year ? If it was that bullet proof people wouldn't be swapping at the same cost sun coast or revmax sells the comp units for that's only rated to 800hp vs a 1,500 hp rating for the same price on a 48 installed
Click to expand...

This trucks in the mid 800s and honestly doesn't miss a beat.
 
You must log in or register to reply here.
Top