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T310m on its way out


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Hello fellas.

The t310m in the granite is grinding while in gear and truck won't move while in low range.it just sits there and grinds similar to trying to engage a PTO without first pressing the clutch.it used to be an intermittent issue , but now it has gotten progressively worse these past few days.trans is not the original t310m from factory since it has a Weller tag on its side.there is no one really dedicated to rebuilding mack transmissions in my area and I'm leaning towards an 8ll swap.i guess my question is if the issue described could be something simple or if the Eaton swap is a better option.

 

PS :I have done mack to Eaton swaps before so I know what I'm in for.

thanks

Red

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If you lose high suddenly you are better off than a progressive loss of low. If you crack a snap ring your high is gone instantly and you may get away with less than $400-$500 in hard and soft parts. Pop your tranny window and see how much grind damage you have. Nothing wrong with an 8LL

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I'll also drain the oil and see what comes out.when the gear does seem to work sometimes it pops out with a tremendous noise and jolt that is felt in the cab.then I'm left at a green light trying to panic shift.

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Two fairly quick and easy checks and repairs would be checking the range shift cylinder o-rings. #1 in the picture could be your culprit for jump out of low range, if you have oil in this cylinder you definitely have a bad seal.  Secondly, check the yoke bolt is tight on the back of the transmission.

image.png.0056092cc8bba09bf2d6feb18fa69bf8.pngimage.png.a08b65713027e7c3b5f6b5be79df1e21.png

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9 minutes ago, jkruss82 said:

Two fairly quick and easy checks and repairs would be checking the range shift cylinder o-rings. #1 in the picture could be your culprit for jump out of low range, if you have oil in this cylinder you definitely have a bad seal.  Secondly, check the yoke bolt is tight on the back of the transmission.

image.png.0056092cc8bba09bf2d6feb18fa69bf8.pngimage.png.a08b65713027e7c3b5f6b5be79df1e21.png

Can this be addressed from the outside or does the tail has to come of to change seal?

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Just a small correction to the above note! 😂 

Two fairly quick and easy checks and repairs would be checking the range shift cylinder o-rings. #1 in the picture could be your culprit for jump out of low range, if you have oil in this cylinder you definitely have a bad seal. >>>Firstly<<<, check the yoke bolt is tight on the back of the transmission.

The range cyl can be removed with out taking the trans out as long as you can make the room under the cab /exhaust out of the way to get the rear lid off!you need about 8 inches!

Edited by fjh
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1 hour ago, jkruss82 said:

Two fairly quick and easy checks and repairs would be checking the range shift cylinder o-rings. #1 in the picture could be your culprit for jump out of low range, if you have oil in this cylinder you definitely have a bad seal.  Secondly, check the yoke bolt is tight on the back of the transmission.

image.png.0056092cc8bba09bf2d6feb18fa69bf8.pngimage.png.a08b65713027e7c3b5f6b5be79df1e21.png

Can this be addressed from the outside or does the tail has to come of to change seal?

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18 hours ago, R.E.D said:

Can this be addressed from the outside or does the tail has to come of to change seal?

Make sure you don’t put too much lip stick on the corpse. If you're chewed up inside no external fix will be useful. Start point is making sure you have at least 60% of solid, untapered, tooth engagement surface left on clutch teeth. You did “progressive” damage. All soft parts, seals, get changed during synchro fix. If it’s ground down your already pulling the rear case and cylinders, covers, yoke, etc. 

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12 hours ago, Mack Technician said:

Make sure you don’t put too much lip stick on the corpse. If you're chewed up inside no external fix will be useful. Start point is making sure you have at least 60% of solid, untapered, tooth engagement surface left on clutch teeth. You did “progressive” damage. All soft parts, seals, get changed during synchro fix. If it’s ground down your already pulling the rear case and cylinders, covers, yoke, etc. 

Ok will do.worst case scenario only the back box needs to be removed correct?

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8 hours ago, R.E.D said:

Ok will do.worst case scenario only the back box needs to be removed correct?

In every case I’ve repaired one, yes. You may want to sweep basement of PTO and front box and clean magnets. You’d have to have a real grenade to take out the front. It’s a good time to take a look around, especially at the “Polish exploder”. There’s a large mid septum, main shaft, ball bearing that sheds its race if you look at it wrong. Its the.only bearing in the trans that says “Poland” on it. Cosmopolitan I guess? 

Mack isn’t as vulnerable as Fuller with their putting the PTO at lowest collection point for junk accumulation, but in either case I’d clean the PTO out and check it’s bearing play. Transmissions survive synchro failures, they seldom survive a catastrophic PTO failure. Usually synchros give your lower countershaft bearing rollers a bad case of freckles, about it though. 

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6 hours ago, Mack Technician said:

In every case I’ve repair one, yes. You may want to sweep basement of PTO and front box and clean magnets. You’d have to have a real grenade to take out the front. It’s a good time to take a look around, especially at the “Polish exploder”. There’s a large mid septum, main shaft, ball bearing that sheds its race if you look at it wrong. Its the.only bearing in the trans that says “Poland” on it. Cosmopolitan I guess? 

Mack isn’t as vulnerable as Fuller with their putting the PTO at lowest collection point for junk accumulation, but in either case I’d clean the PTO out and check it’s bearing play. Transmissions survive synchro failures, they seldom survive a catastrophic PTO failure. Usually synchros give your lower countershaft bearing rollers a bad case of freckles, about it though. 

Unfortunately there are a few special tools to do this job in the truck and  the parts will not be cheap these parts are usually available thru PAI at a bit better pricing how ever it will still be pricey!

Just saying!

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I hate to loose the multi speed reverse along with not keeping the truck original but in the long run Eaton Fuller parts and service are faster and cheaper than Mack .(at least in area).

As soon as I come back from vacation , I'll look into the 8ll and keep the t310m as a back.(I plan to repair it properly once the slow season kicks in).I have Eaton Fuller cores at the yard so I won't have to turn the t310m in .

I also have drive shafts to cut to lenght since I think the 8ll is probably shorter. 

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  • 3 weeks later...

Finally got back from a much needed vacation and got to work on the transmission.took the rear cover off and below are the pictures of what seems to be the culprit.

Not sure what the specifications are for shift fork wear but this one seems to be very worn.please advice.

 

Thanks 

Red

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Fork not horrible. Clutch plate receiver for fork worn badly, but not destroyed. Both need to be replaced. How chewy are the slider clutch teeth? Need to get a pry bar in and move the plate both directions now that fork is out while scanning the teeth. 

Edited by Mack Technician
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You may need a long list of stuff. All soft parts, Clutch as a replacement unit, fork, hub bearing, rear seal, snap rings, etc. Need to condemn what you can readily see before you can decide best practice. You see eroded teeth you are moving toward more expensive and invasive. 

Edited by Mack Technician
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54 minutes ago, R.E.D said:

I will do that.by chance does anyone have pai part numbers for these two items ?local mack wants 488$ for shift fork alone.thanks

I’ve pulled reman trans forks out and they hard wire welded the fork pads and cut them back down. Reman company’s find ways to make reman profitable. 

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I have owned the truck since late last year and it always had that symptom.the transmission seems to have been rebuilt not long ago by weller.it has a Weller tag.i will call them and see if it may have warranty or at least a quote on repairs.

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Update..I stick welded the worn part of the shift fork and built it back up... transmission is running like a champ now...I'mma start looking for a suitable replacement , preferably a 8ll .

Thanks to all of yall .

Red

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Awesome save RED! 

The ring that receives the fork is definitely worn. I realize it’s back in, but for anyone else, don’t be afraid to add metal to fork, past original thickness dimension, to compensate for both (fork and slider) worn surfaces. You have nothing to lose.

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6 minutes ago, Mack Technician said:

Awesome save RED! 

The ring that receives the fork is definitely worn. I realize it’s back in, but for anyone else, don’t be afraid to add metal to fork, past original thickness dimension, to compensate for both (fork and slider) worn surfaces. You have nothing to lose.

I used a caliper micrometer to measure the ring and it was about 15mm .I built up the material in the fork and then ground it down to around 14.8 mm to give it some breathing room. 

The fork originally had a thickness of around 10.5 mm , those extra 4.5 was the needed push to make the low range clutch engage.

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