jkruss82

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.

Mack has always offered a shiftable multispeed reverse.  Below sales specs are the latest models from about 2000-present.  Pre-2000 models were T200s with similar 'M' to designate multi-speed revers.

T-310M 1361311 9-29-05.pdf T-310MLR 1361313 9-26-05.pdf TM-308M 1361324.pdf TM-309M 1361325 9-26-05.pdf

20 hours ago, Talldawg said:

First time poster here. I drive a 2005 granite with a 10 speed, multi speed reverse, maxi torque transmission. Low range has 2low-1low-1-2-3-4. High range has 5-6-7-8 situated in the same places as 1-4. This leaves the 2lo/1lo spots with no marked gears in the high range(I will call these 1 and 2 lo-hi). When you select one of those spots in high range however they do have functional gears. 2lo-hi has a gear ratio between 1st and 2nd and 1lo-hi is between 3rd and 4th. The only practical use I see is shifting from 3rd to 1lo-hi and on to 5-8. Are these gears safe to use? And why are they there?

The gears are there because that is how a compound range transmission is designed.  All the High Range gears (Direct drive through the range) get a Low Range (approx 4 to 1 reduction).  The multi speed reverse was designed as an 8 speed with 2 hole/low speed gears. Additionally you can use all 6 speeds ratio's in reverse

You will not damage the transmission by using them, but you will have difficulty using them in a practice, because the hole gears are not meant to be shifted thru in high range, they are meant only for low speed use.

4 hours ago, mackinit said:

luckily i was able to find the owners manual and it explained a lot. what it doesn’t say is at what rpms to split at. say at 1600 rpms, i want to down split, do i hit the button down while on the throttle? or off then hit it? i tried a bunch of different ways and it didnt work either way for me. is 1600 to high or should i be down splitting around 1400? 

200 rpms is either direction when splitting.  If at 1600 revs you want to split down: hit the button down, then you need to tap the throttle, let off to break torque, then throttle up to 1800.  I'd say that 1600 is a little high to be down splitting, but can't say for sure what you are trying to do.

Pretty big undertaking.  Special transmission wire harness, and engine wire harnesses needed. Does the donor chassis have the same engine type as your RD, then maybe you could just pull the donor ECM. Not sure about component shop flashing new software.  Flywheel housing should be the same, but flywheel needs swapped out and you need the spacer ring. Allisons are very heavy and require rear buggy spring mounts at the rear of the transmission, so you probably need to fabricate brackets on your frame.  I'm not familiar with where the RD rear engine mounts are located (Flywheel Housing or Side of transmission) in either case they will not likely be the same.  There would probably be more headaches along the way, that I'm not thinking of.

Hate to say this, but I'd recommend trading your truck to get the transmission you want.

Pic of buggy spring

Its a 425HP engine.  338 may be the hp at 2100 RPM, but max hp is around 1600-1700 RPM.

Forward 6+2

Reverse

You can probably make this work as long as you pay close attention to plumbing the correct air and oil lines.  You will also need to be careful with driveshaft angles, since the input and output shafts have a pretty large offset.

Also there were lots of different HI and LO ratios available on these units. 

for example TC15 LO-2.59 HI-1.00 and TC25 LO-2.59 HI-1.36

Good luck if you try this.

Recommend checking air pressure on both sides of the shift cylinder and shift between Hi and Lo, and do this with a warm transmission if possible.  Its possibly you just need some seals 

I've generally heard that the shifting gets better on a warm trans, but in your case the opposite could possibly be true.

If its the splitter, its the top cover on the back box that possibly needs to have the air cylinder rebuilt (new o-rings, maybe new brass air fittings) and check the air lines and other fittings on top of the transmission.

4 hours ago, Hayseed said:

The  Mack 10 & 18 Speed is listed here as an option on the Granite Only.

i got a Quote on a granite a couple of Months ago & asked about the Mack Transmission. Salesman looked at me as If I had 2 heads (Be quite Swishy very Quite) he told me that 90-95% of the Macks they sell have the "M drive" The rest were Road ranger & he'd Never Sold a Mack transmission in the 6 yrs He'd been selling Vomacks..

Unfortunately Australia tightened up their noise regulations and Mack dropped their manuals from being offered about 6 years ago.  I think you may be able to special request one, but I would hate to know the cost.

In the USA Mack sells mDrive, Allison, Eaton, and Mack T300.  About 20% of trucks still have a stick, the other 80% do not and that number continues to grow.

The Mack 6 speed is gone from production.  It was nice and lightweight for a class 8 truck, but drive-ability and reliability not so great.

Mack's manual transmission take rate is about 10% of new trucks.

Mack has the most PTO options available and a 10 speeed multi-speed reverse (T310M) that is shiftable through 6 reverse gears.  Otherwise Mack and Eaton match up pretty close with 9/10/13/18 speeds.

it may be for flywheel PTO

New Picture.bmp

Sounds like it may need new seals and o-rings if the air lines are all still connected properly.

Whats wrong with the Mack 13spd if you don't mind me asking?

For the Eaton you can use either aluminum or cast iron bell housing with the correct clutch release.  You will probably need a longer prop shaft as well.

Do you mean shaft? Dig those swivel clips out with a flathead screwdriver and punch the pin through.

The pilot bearing floats in the flywheel, nothing holds the new ones without snap rings.  Good idea to replace the pilot bearing, they tend to go bad from the clutch dust and such.

Is this a new transmission or does it have a many miles?  Sometimes a gear will have a bad spot and sound like a knocking during coast.  If you have a T310 and its in low speed, the gear set directly behind the mainbox (in the rear box) is most likely the culprit of the knocking noise.

That being said this noise may go away after the bad spot gets worn down, but that's only if this is a new or Reman new transmission.

If your MP8 is rated at 1860 ft-lbs you'll need a VCT+ clutch rated at 1860 or higher.  The Mack 9-spring will be getting a rating increase in April of 2017 to match the 1860 ft-lb engine rating but Eaton will not warranty the current 9-spring at 1860.

your correct about the springs in the disc dampening the chatter and shock from the crankshaft.

nickname is the Plum

Rear section countershaft gears are welded on the shaft .  That would take some effort.

Not sure how you could change around any  other top two gears???

If it sounds like its coming from the transmission then it may be the reverse gear set in the back box.  In 7th and 8th the reverse gear set is spinning fast and is not loaded so it may sound like a lot of rattling.

If the offered 6 speed is a T2060 then it has an air shifted hole gear.  The ratio is 9.02:1 which is much deeper than your 5-speed with a 5.24:1.  To install you will need to cut down a drive shaft because the transmission is about 8 inches longer and you will need a shift knob with toggle switch. 

If the 6 speed is a T306G, it will have a 1st gear ratio of 7.5:1.  It would fit the same as your 5-speed and should be a simple swap out.

What kind of noise is it?  You may need a new overdrive gear on the main shaft, especially if the unit ran low on oil for a length of time.