mack 18 speed problem

[Mack Technician 710]

If they left the thrust washers in production instead of a thrust ball bearing none of it would have happened. They undercut the snap ring land to half depth so the bearing could be used. We reverse engineered some back to original shaft style till we ran out of parts. 

Did an in chassis sychro this summer on a buddies log truck. All updates installed in a T3. The double thick snap ring no longer pops off like the wimpy original......it shatters and runs through the gears. He called and said he had no high, so limped home in lo. I was picking bits out of everywhere, some rolled flat from gears, but no real damage. Reused everything but installed a new ring. Synchronizer looked fine, well preserved. But, yeah, better, no perfect fix.

Edited December 3, 2018 by Mack Technician

[mackr1989 2]

so how many synchros are in this transmission for splitting gears? the only problem ive had is splitting from underdrive to direct and vice versa. never had a problem with high and low range. 

[Mack Technician 710]

None.

 

Range has a synchro, that’s it. 

[mackr1989 2]

so just range as in high and low..not underdrive and direct? 

[Mack Technician 710]

10-4!

[mackr1989 2]

in an 18 speed? why do you think i was told that there is 6 and that they were all worn?

[terry 316]

1 hour ago, mackr1989 said:

in an 18 speed? why do you think i was told that there is 6 and that they were all worn?

Are you saying you were told there were 6 synchro's? As Mack T said only synchro is on range. The other gears have what some guys call dogs, don't actually shift the gear, move the dogs to engage gear, gears stay engaged all the time, sound confusing?      terry Maybe get an exploded view of trans to help you understand it.

[mackr1989 2]

im going to call the company that did the transmission work and relay what you guys are telling me cause i was told much different. if my problem with this transmission was gear splits not meshing together causing neutralization and or rough engagement, what do you think happened to cause this? im now understanding what mach tech is talking about and didn’t at first due to what i was told previously by other people.

[fjh 441]

On 11/9/2018 at 4:58 PM, Mack Technician said:

Your operator conscience is good and sound and telling you “this is not good, this is not smooth, I may kill my money maker, I gotta figure this out before I damage something”. Find a guy who has years on his truck and only used up 5 of the 15 minutes of total lifetime grind in 500K miles. Have a good pow-wow with him and see what he does, buy him lunch. 

Yup agree with Tech Get on the powwow There are occasions where the shift lid is at fault the shift fork pinch bolt has loosened off  how ever I would do as Teck has stated for now if possible!

I also want to clarify Are you still getting a grind on the split! Some have come to our shop and complaining of a split grind when in fact they are combining the shift with the range shift ! 

Edited December 4, 2018 by fjh

[mackr1989 2]

no grinding at all. i range shift, move the shifter, then split.

[terry 316]

53 minutes ago, mackr1989 said:

no grinding at all. i range shift, move the shifter, then split.

So without going through every post, what is the problem?     terry

[mackr1989 2]

the problem was the gears weren’t meshing together when splitting from underdrive to direct and direct to underdrive while in high range..no problem with gears in low range. splitting in high range would put the transmission in neutral and or neutralize then knock into gear. i was told that all of the synchros were worn and thats what was causing the problem. i put a reman in because it wasnt going to cost much more than repairing what i had. now it shifts fine in every position.

[Mack Technician 710]

https://macktrucks.vg-emedia.com/ProductDetail.aspx?ProductId=6330

You should download and keep this, it is a free OEM Mack manual for that trans...Could help you understand the interior of trans.

9 hours ago, mackr1989 said:

in an 18 speed? why do you think i was told that there is 6 and that they were all worn?

Because the person you use is a crook or an idiot, possibly both .

Edited December 4, 2018 by Mack Technician

[terry 316]

Mack T maybe his shop is calling the dogs or sliding clutches a synchro?     terry

[Mack Technician 710]

3 hours ago, terry said:

Mack T maybe his shop is calling the dogs or sliding clutches a synchro?     terry

I prefer to think your right, but consider the number 6. He dreamed up a synchro on each side of sliders.......

They replaced the trans and something was fixed cause he is driving it and liking it.... so good job? 

Edited December 5, 2018 by Mack Technician

[Challenger 102]

Sounds like the shop doing the work doesn’t have a lot of gear experience.  You’re better off with the reman instead of some fresh out of tech school apprentice learning on your trans.  

[steeler 10]

Just curious, how much did you pay for that reman? If your problem was the syncro, that could have been done much cheaper.

I don't know what idiot told you that you had 6 syncros in there, but stay away from that guy.

 

[mackr1989 2]

terminology was wrong when they were saying the synchros were bad. the clutches were worn amongst other things. $5200 was the cost of the reman.

[steeler 10]

6 hours ago, mackr1989 said:

terminology was wrong when they were saying the synchros were bad. the clutches were worn amongst other things. $5200 was the cost of the reman.

Damn. You don't see sliding clutches worn out in a Mack trans very often. They can take a lot of abuse and still function just fine. Unless someone was VERY abusive to it, or whoever looked at it doesn't have much experience diagnosing them.

[Mack Technician 710]

On 12/4/2018 at 6:07 PM, terry said:

Mack T maybe his shop is calling the dogs or sliding clutches a synchro?     terry

 

On 12/7/2018 at 3:26 AM, mackr1989 said:

terminology was wrong when they were saying the synchros were bad. the clutches were worn amongst other things. $5200 was the cost of the reman.

Terry, I recant of my harsh criticism, brotherman was just looking at the 6 worn engagement sides of the mainshaft sliders. BMT lesson- approach misinformation cautiously.