Wasteaway

The saga continues. I finally got some time today to take a close look and I removed the top plate for the 20th time and this time was able to determine that the shift forks are all in the groove of their designated selector gears. i positioned the cover so I could peek inside just before dropping it completely down and determined that the forks are aligned. Nothing has changed. Shifting is impossible, yet nothing was removed internally. Again, there is an "Electrical malfunction" light flashing on the dash, the throttle pedal is grounded, and the clutch does disengage when depressed. I, along with everyone I have spoken to is stumped. Any more suggestions?

I think I know exactly what you're talking about. I can see down inside when the plate is up, but not to the rear of the transmission. I suspect the rear fork is not in place in the slider gear, which cannot see. I'll try it once more by feel and if I can't get it I will open a side plate or jack the cab to remove the plate altogether. Just didn't think the fork could miss and the plate fit down smooth and all three rail blocks in the neutral position. To me that indicated that the forks were all home. Gotta be something stupid because I didn't take a thing apart when I was in there.

Thanks Carlot. The floor pan is up but restricts the plate from being removed more than about 7" high. My next move was to jack the cab from the rear for more clearance but even with that you can't look inside while setting the plate down. Thanks for letting me know that it is possible to be misaligned and have the plate sit properly. I will take mack tech's advice (thanks) and see what I can find.

Its possible for a shift fork to miss its correct location and not affect the cover setting down smoothly? The three "blocks" in the top plate that slide on the rails are all centered creating a clean "square" for the shifter "tail" to set into. I assumed that a shift fork out of place would cause one of these three blocks to be misaligned when the transmission is in the neutral position. It sure feels like a shift fork is not in its proper location.

Everyone I asked is stumped. I bought a 2001 RD688 Western Contractor with a 350 Mack engine and 9LL Fuller transmission. With the truck came every service record since day one. Having seen three times where the previous owner had to retighten a set screw in the transmission (once fishing it out of the bottom) I decided that while the truck was idle to remove the top plate of the tranny and take a look. Upon seeing safety wire in the set screws that hold the shift dogs in place I assumed that the problem was addressed and fixed once and for all. I now believe those set screws come safety wired from the factory....but that "issue" is not the problem right now. When the cover was "up", only high enough to look under because the floor doesn't allow for removal of the plate, I did ABSOLUTELY NOTHING to the inside of the tranny. I set the cover down and buttoned it up. Months later I went to drive the truck out of the garage and it will not shift into any gear except reverse if I hold the shifter tight to the gear as if it is going to slip out. So reverse, first, and third will chatter against the gears with the clutch in. Second and fourth will pull hard but never contact a gear. The shifter moves freely. I have removed the tower several times. The detent balls and springs are all in place. The high/low range selector does not always "click" with the normal loud thud. There is a light on the dash that flashes "electrical malfunction" that I don't recall being on before. The throttle pedal is now grounded with no change. The truck drove and shifted perfectly when brought in. I'm not familiar with any transmissions beyond understanding their basic internal function. I have contacted several "experts" to no avail. Many suggestions but none have born fruit. Anyone here have an idea? Thanks for your efforts in advance. I haven't been on here in a while but I know from lurking before that there are some her who know their snit.

If your gonna part with it, let me suggest you bring it up to New England. You think its rusty? You ain't seen nothin'. Plus, here in Rhode Island, you can legally load those axles to there limit so a heavy spec truck has value up here.

Oh, and the post I was referring to was here And I read this; Hey HK, I put the back box off a 13 speed on my 9 speed and we changed the top gears in the rear ends to 16-17 to come up with a 3.86 ratio and it all works great. I to was concerned with take off and hurting m............

Not more speed. I actually have a 13 in my "old" truck and a 9LL in my "new" 2001 RD688 and I am thinking of swapping them before the International gets sold. The two trannys have the exact same ratios in the upper four gears (on the high side of the 13) and both are .73OD final drives. The beauty of the 13 is the RPMs can be kept in the fat part of the power curve, less lugging and less revving. Come to a hill, split the gear. The 13 can run in a 3-400 RPM range. I expect the Mack to have to be revved more before shifts and lugged more in the next higher gear and/or not be able to pull the next gear. Just for more versatility. Easier on the truck.

I have done some research on here about converting a Fuller 9 speed to a 13 speed and I learned about the "c" designation in the serial number denoting a 9 speed that is designed to be easily made into a 13. I have a 9LL and ran the serial number and it is an overdrive transmission, but no "c" designation. Its my understanding that ONLY the 9 speed with the "c" can be made into a 13 but I just saw this post so I am now wondering if ANY 9 can become a 13 and if so, what is required?

Thanks for the replies. Thanks Dave for the files....good stuff. I can't help but wonder why the 38s would have larger bearings than the 44s. I'm sure I will pour over this info at a later time. At least you guys reassure me that these rears aren't weak by any or most standards. As an owner/operator I seldom have any truck issues, much less any abuse related ones. Looks like a lift axle will be in order for my application.

I have a dilemma. I purchased an RD688s with the belief that it has 53,000# rears. This number seemed odd to me and yes, shame on me for not making damn sure before pulling the trigger. I did call a local dealer and without any hints, he stated 53Ks, among other things such as the engine, rear axle ratio (4.42) and front axle rating (20K) which I can confirm accurate. This info was from the vin (Mo57706). After getting the truck home from some 600 miles I can find no evidence of 53K rears. I do have the build sheet on the truck which does have some discrepancies, it shows Mack 38000 - SB38 with a PID code of 268-1003. The truck was purchased new through McNeilus as a mixer and two lift axles were installed at the time. Now things get fuzzy. The dealer stated he could not determine the axle rating because of the Hendrickson Walking Beam suspension. Hendrickson lists the HN462 as 46,000# springs which is what the build sheet shows. So it seems the truck has 38k pound rears over 46k# springs. Here is the big question........are the Mack SB38s the same axles (axle housings....wall thickness, etc) as the Mack 44,000 pound rears? Is it the same axle with the springs determining the capacity or are the axle housings different on the heavier axles? I can live with 38s if they are the same as the 44s (design and strength) with the Hendrickson suspension but I am going to have a tough time with 38k axles if they are pretty light duty. I would think, as a mixer, this truck saw some pretty heavy loads off road every day and I am certain the axles are original as I have every service record from day one. Sorry for the long winded post

Huh. Who knew? Makes sense.....not the law, the explanation.

A local guy got fed up with emissions issues and has since bought several '80's Macks and gone completely through them...maybe $50k (so the story goes) which I can see if you do it all and do it right.... and you end up with a "new" truck that can be rebuilt/repaired in every way with better reliability than going with a new rig. This is what I am shooting for with my new purchase.

Sorry, I just saw your reply Milkman. The truck is a 2001. Pr- EGR E7 350.