2005 CV713 Maxitorque T310M/MLR Synchro Help

[Detailed0707]

Hi all, have an 05 cv713 dump truck with a maxitorque T310m/mlr trans. I am getting a loud grind in neutral when coming from lo to hi range gears. Preselect or not preselecting, grinds nearly every time with no avail. Specifically 4th lo to 5th hi. Through lots of research I see the common culprit being the synchro issue. My question is trying to ensure I have the right part number fix before ordering. I have also seen to order through PAI for a cheaper alternative to Mack OEM. Is PN 806806 the correct kit I need to fix my lo to hi grind? Just double checking before ordering. As a side note, any recommendations for best site to order these from as there are several selling PAI with different pricing. Thanks in advance for the help!

[Joey Mack]

What you describe is typically the synchro..  who is doing the repair?  An 'in-Chassis' repair is doable, however several essential tools are needed, as well as experience..  I'm not trying to be a jerk, I just have seen many guys who work on other brands, try to do MACK component repairs, and find out they are in over their head..  with respect, Jojo

[Mackpro]

I always hated working on mack manual transmissions  but as Joey said the in chassis repair can be done with the special tools but it’s still no fun . There are 3 things we have found  that cause synchro failures in the Mack manuals trans . Number one thing is the set screw for the high/low range  fork backing out. This is a common problem. The 107 series and early 200 series transmissions had a set screw that was drilled for safety wire. I remember the old guys rebuilding them in the 80’s using the safety wire, wish they still used it . Second thing is the stupid rear yoke bolt and washer set up . This has been a pain for years . A lot of the time we find the yoke bolt and  washer missing and the only thing holding the yoke on is the pressure from the driveshaft/carrier bearing . These two things greatly affect the high low synchro. The third thing is driver error. Upshifting not so much but when downshifting and flipping the hi/low range to low at to high a speed seem to make cause a lot of bad noises. I only range shift from high to the low side when I’m almost to a full stop. 

Edited January 21, 2023 by Mackpro

[Detailed0707]

Yes, so the repair will be me along with another guy who has done one of these in the past. Still remembers the process vaguely but had someone teaching him the process many years ago. Shop cost would kill me on one of these since I am trying to get it ready to be ran and make some money before dumping loads back into with a shop if at all possible. I have read up about all the special tools needed to keep the counter shafts in time and in place along with keeping synchro in place during removal. That seems to be the most daunting part of this whole repair for me at least. I did find the manual E-Manual thanks to Mack technician posting it back in 2021 for the in frame repair. Set screw is definitely something to check I’d seen a lot about. I did check the rear yolk bolt first hoping it was possibly loose, but all is tight and well there. The local Mack dealership near Middle TN is not very reputable and quoted an outrageous price for parts + labor + an essential diag charge they claim they have to do. Not in the cards for me, so it’s all on me and my buddy to get it straight. Quite the task for sure so just trying to make sure I atleast go in prepared with all correct parts before even tackling it. Definitely nervous about it but trying to tackle it with what info I can find online about the job so far in addition to the manual. 

[Joey Mack]

when you assemble the new synchro pack, pay close attention to the position of the bascket..  the letter 'R' is stamped into the studs in the basket, that is to the 'rear'..  also, dont forget the snapring inside the center of the synchro. for some reason I have seen guys forget that and it will only shift once,,,,  then its comes back apart.. also, pay attention to disc postion.. the friction discs and the pressure plates..  I have the service manual for this tranny, so if you need a picture, I can post it..  jojo