Md3060 issue 300 miles from home..help asap

[50 crown]

Need to figure out whats going on, the top of 4th gear sounds like massive grinding at 1800 rpm has a hard time shifting to 5th . 5th and 6th as well as 1st 2nd ( and I think 3rd ) all shift smooth as silk still. I’m thinking of limping home to save a big tow bill.
Any ideas?? Thanks

[FatBoySTL]

It's a long shot, but can you run the RPM up in 3rd and shift to 6th? If you're doing mostly highway miles, this seems like a viable limp-home plan. I've had plenty of small gassers I could do this in, but I'm not sure of the gear spread in these big boys.

Otherwise, what's top speed in 3rd?

[joeblack5]

How does the oil look..any codes ?

[50 crown]

Ya it’s electronic shift pad. I attempted it however it will only shift in order. So far in the the am im pulling the plug and cleaning/ inspecting the pins very carefully, also going to check the tps and see it it’s out o f range. We shall see
Thanks

[joeblack5]

Is this an original 6 speed TCM or after market?the 3060 is easily available. If it is something serious as a gearset or bearing then you are in high $$ anyhow. It is stressful to be in that situation. Start looking for another 3060 along the way home and keep limping till you find a tranny shop that understand 3060 and has the gear to trouble shoot.

Good luck.
Johan

[50 crown]

It’s the original tps, ya the bus dealer I purchased the tans from thinks he has another in good shape. Or i might just get a new build to be safe if thats the Issue. I will do some more diagnostic work today before heading out and see what else i find.
Thanks

[joeblack5]

Maybe some confusion here the TCM = transmission control module.. TCP = ?? with the 8.3 you should have a throttle position sensor.. TPS.


There are some tricks to read out any codes with the keypad.



Good luck, J

[50 crown]

Yes I have a TPS. And can you believe there is not even 1 code in there.. and a little update we made it home lastnite ! Grinded horrible at 1900 rpms all the way home. By the time I got off my exit and pulled that last hill half mile from my house it was so loud in all gears lol.. I bet if I had 2 miles more I would have been towing it ����

[joeblack5]

Congrats on your return, no codes.....may be your flexplate cracked?

[bus-bro]

Getting home without big tow bill is a plus, though now you get to find out what got tore up.

[50 crown]

Wow wouldn’t that be easy fix.. ok so after reading that I went and stuck a scope up in there as best as I could and it’s possible that there is a little gap from the plates to the center hub. However the camera is at a angle so it could just be the view. I guess it’s up on blocks and pull the trans time..

[50 crown]

Yes big plus.. and ya now I start a spendin... ��

[cadillackid]

glad you made it home.. flexplate issues will usually manifest in all gears.. converter clutch failure and chatter often only manifests in certain gears.. that trans wont lock up factory until 3rd.. is it grinding in 1st and 2nd now too? always at the higher RPM and not the lower? worse on accel. vs decel vs detente(where you are not saccel or decel.. light pressure on pedal enough just to keep it moving)..


having "trouble" going into a gear is usually a slip.. the grating sound is usually overruning a clutch pack( its trying to stay engaged and you are slipping it)..



the C1 and C2 take the brunt of it in a 3000.. C1 is engaged fully in gears 1-4. and C2 comes on going into 4th..



the 3 to 4 shift is a heavy one as you are dropping into 1:1 and often doing it while in hard accel running the engine to redline or close to it.. that C2 clutch builds a lot of heat.. ...


its hard to tell without taking it apart.. solenoid issues will generate error codes and check trans or shift inhibit lights.. spinning clutches will usually generate output and turbine speed discrepency codes..



its also possible you have something simple like a bad U-joint causing a resonance that manifests itself at certain driveline and engine speeds..



id probably first drop the pan on the trans and look at the magnet.. see if there is evidence of heat in the fluid, lots of clutch sludge.. pieces of snap-ring on the magnet.. (a simple broken snap ring (and there are lots of them in an allison) can cause major issues)...


if youre grinding is tinny and metallic id begin to suspect a sprague or stripped out sun gear..


-Christopher

[50 crown]

Wow.. now were talking transmission talk..
Ok I first heard and felt the going/rumbling on a crest over a big hill when it sifted from 4th -fifth. Was right at 1900 rpm and only lasted till it shifted ( a few seconds ) then a few hundred miles later i heard it again pretty much same scenario. Then nothing again till I pulled a big hill and as before only in forth gear.
Then after making the call to limp home it had a hard time shifting to 5th.. like it was stuck in forth. By the end of the trip i could hear it at high rpm in all gears. I pushed the bus to 1900rpm in 6th and sure enough it started to grind.

I pulled the dip stick and fluid looks brand new, smells new, however i did get a little black sludge stuff on the Bottom of the dipstick 1 time. And just wasn’t sure if i scraped something dirty while attempting to get the stick back in the tube. So i guess pulling the driveshaft ( it was just built before this trip ) as i just changed to the the 3060 ( had a manual transmission before ) the trans needed a shorter DS and if that check out pull the pan and see what we got there.

Thank

[bus-bro]

Yeah, from what you wrote the drive shaft would be the first place to look. Maybe just U joints. Not that I know all that much about it, but I do know that
reconfiguring a drive-line can be a complex problem.

[50 crown]

Ok well I pulled the driveshaft and 1 joint turns smooth as glass and the other side I have to hold the driveshaft with one hand and can barley turn it.. I don’t think it should be that tight.. I can feel a bad spot in it when I do turn it..
not sure this would create what I was experiencing especially when the trans didn’t want to shift at all out of 4th and the vibration happened when I raved it to 1900 rpm in neutral.I will take it to the driveline shop Monday and have them look it over.

[ewo1]

Originally Posted by 50 crown

Ok well I pulled the driveshaft and 1 joint turns smooth as glass and the other side I have to hold the driveshaft with one hand and can barley turn it.. I don’t think it should be that tight.. I can feel a bad spot in it when I do turn it..
not sure this would create what I was experiencing especially when the trans didn’t want to shift at all out of 4th and the vibration happened when I raved it to 1900 rpm in neutral.I will take it to the driveline shop Monday and have them look it over.

U joints should moe freely and smoothly. anything else besides smooth, inspect and/or replace.

My silverado 3500 had a real bad vibration and grumbling at very low speed, crawling at idle I could feel a bad grumble/vibration.


Turns out when I last did the ujoints I did not realize that one of the rollers fell out of place and was lying flat in the cap.
At high speeds, didn't notice it but again at low speed/crawl...you felt it.

Hope your issue are as simple as a bad u-joint!

[Dirtdoctor]

I’ve a 98 4900 with 530E and the 3060 Allison. The key pad does fail. I’ve replaced it twice since buying it brand new. Could be the keypad. Dealer has a computer and can read the codes. Good luck
Cheers

[Willie_McCoy]

Glad to hear you made it home without a tow! Hopefully the u-joints turn out to be the culprit. This is exactly why I'm keeping the stick.

What did you do with the 10 speed that you replaced with the Allison?

[50 crown]

Update : trans is 100 percent fine. Had it dyno’d
I figured it was after pulling it out and THEN discovered that 3 of the 4 bolts on the fan bearing were snapped off and only 1 bolt holding it on, it was sideways and flopping around in shroud. I’m guessing that at 1900 rpm is when it would state getting out of control and hitting the shroud hence the noise.. well at least i found the bad U joint in the driveshaft !! And i no the transmission is in good health lol.
Thanks to all you guys for helping