Brandt

What drives my speedo and where do I find it?? For the last year my speedo has been working when it wants too. Sometimes reading properly and sometimes showing 15mph when I'm at highway speeds. This also goofs with my odometer as I have only gone 550 miles in the last 9 months. I looked on the trans and found no cable driven port. Is it air?? Electric?? Does the cable come off of the top?? 1991 RD 690 TRTXL1070B - 12 spd w/.78 OD CRDPC92 & CRD93 diffs with SS440C axles It is due for a triple box oil change. I am going to run Amsoil in the trans and diffs. What weight do I need in each?? What is the capacity of each? It looks like the trans has 2 drain plugs - is that correct?

I bought a spare housing from Mack in case I crushed mine. I turned like there was no tomorrow and it loosened up and came off w/o crushing. Mack took the part back and I am $97 richer!! Thanks guys.

It is stuck on there good. It's gonna take lots of Kroil and some heat.

How do I get the centrifuge oil housing off to replace the element???? Last time I skipped it, but I can't do that again! EM 7 300HP Maxadyne

Finally got the high flow injectors (ADSKBAL137P26HFEX) and turbo (SCH174828) in. The truck runs a bunch better!! Before, my empty mpg was 7.4 to 7.5. Now my mpg is 7.2, but that is 50% empty and 50% loaded at 62K. The most boost I saw was 27psi, but 22 psi seemed the norm. Empty I was pulling 9 psi to maintain 60 mph. EGTs ran about 800, but did spike at 1000 on a 4 mile grade. These are after the turbo readings. I still have 2 problems with it. Before it reaches operating temp, it still sputters and stamers. Once the temp gauge hits 180 it goes away. I thought this was injectors, but after the new injectors the problem remains. The other problem is that in a long pull while loaded, I hear pops and sputterings from the exhaust. I also watch the boost go from 25 to 18, to 23 to 20 and bounce around synchronized with the pops and sputtering. I have done nothing to the fuel pump. I even hesitate writing this because the truck is due for a fuel filter change and it might just be filters. If it is not filters - Am I over fueling it?? Under fueling it?? I have driven electronic engines 98% of my life - what does a fuel pressure gauge tell me and do I need one?? Because I am kinda ignorant on mechanical engines - yesterday I was tooling around at 62K on the flats at low rpm (1000-1300). Does this over heat the pistons?? Cause pistons to crack?? Anything bad? I was pulling 15 psi boost and 800* exhaust temp. My load point and dump point were about 4 miles apart , I wasn't on the throttle very hard as most of it was on a dirt road and there was no traffic that I was holding up. I don't think I made it into top gear all day.

Seems the 315/80/22.5 are the same size as the 12Rs. Good to know info.

Can I run 12Rs on an 8.25" rim or does it need a 9" rim?? The OEM injector # is 736GB343P3. I have a Turbo #, but Google turns up zero info on it. When I'm empty I run the low side of the gears until I reach the top on, then split to the high side. When loaded, I might run the low side for the first shift, then I split them all the way up. I generally shift around 16-1700, as I am conditioned to shift low due to the 1.5 mil electronic engine miles I've done. I don't know what this engine is governed at as I've never ran it up that high to find out. Found the old shop info, it is Antrim Diesel in western PA.

There is only 225K miles and 12K hours on this truck. It was a county plow truck and seems to have a lot of idle hours. I do have to remind myself that it is not a Series 60 and won't go for a million. The build sheet shows: EM7-300L-4VH 1425 lbs-ft TRTXL1070B - 12 spd w/.78 OD CRDPC92 & CRD93 diffs with SS440C axles I would much prefer 4.17 gears, but I don't think I'll ever recoup the cost in fuel savings. With Dayton hubs, I'm kinda stuck with 11R-22.5 tires

OK, 400 is out of reach. I am not familiar with the differences between the Maxi, Econo, Thermo power curves. I can live with 350. I'm just wanting to gain as much as I "reasonably" can due to the increase in weight that I will be pulling. I have a 12 spd behind it with 4.42 gears. I think the 12 psd is a 1050TX???

I have a '91 EM7 300 Maxidyne that has 2 or maybe 3 failing injectors. This was a transitional year and it is all mechanical except for the elec fuel pump. I was told that I could upgrade the injectors and turbo (at the same time) and possibly achieve 400 HP. I have lost contact with this source, but am ready to do the upgrade. Where do I find out what part numbers I need for the inj and what model turbo. The truck works at 4900'-5900' elev and I plan on adding a pup to it. Gross will be around 88-91K depending on how long my pup tongue is.

OK, Thanx

What is the difference when an axle is called a "pusher" or a "tag". I'm wanting to put one in FRONT of my drive axles. I need steerable and a drop axle to clear the drive shaft.

You have every right to choose not to own/carry a gun. However living in America, you will reap the rewards of those who do choose to own/carry them.

Amazing how we say this is "federal" land. It is NOT federal land, it is PUBLIC land the the citizenry has tasked the feds to maintain. Until we stop saying that it is federal land (when it is actually the tax payer's land) we can expect a power grab by the feds every time!!

I have the PDLO switch for my CRD92/93 axles. I was wanting a left to right lock, but it looks like I'd have to get a set of cut-offs.

Thanx guys. I'll get them hooked up on separate switches. Good point on - if conditions are good for 25 MPH, then I shouldn't need lockers. I've heard about the "peanuts" in the Mack diffs, but can't find a whole lot of detailed info.

I just replaced both of my Eaton diffs with "lockers". Now I need to hook up air and learn how to use them. What are the do's and don'ts on using a diff lock (as it relates to Eaton rears). 1) can I engage while moving? (in a straight direction) 2) Can I engage at any speed?? 3) If I have just 1 diff locked, can I turn?? 4) what will shorten the life of the locker? Any tips on how to plumb these in would be appreciated. I have been told to run one air line and lock them in together. I have been told to tie the front diff in with the inter-axle lock. I have been told to run 2 separate air lines to allow me to engage the front OR the rear OR both locker(s). I have been told to tie both lockers into the inter-axle lock and when I though the switch - everything is locked! PS Can I get a similar set up for Mack top load diffs?

I have 5 gal of each oil. The diffs call for 3.5 gal. each. I am reconitioning them now (new bearings and such - same gears). I run in colder climates but am always 70K-86K and only run in the Rockies.

Eaton calls for 75w-90 oil in my diffs. Would it be a sin to run 75w-90 Amsoil in one and 75w-140 Amsoil in the other?

I am not familiar with the DDEC 2 strokes. However on a 60 Series I would suspect the fuel pedal. Is your fuel pedal electronic??

I would be removing a TRTXL to install this T2180. I got 2 quotes; one at $6500 and one "starting" at $5000, to rebuild this one. I haven't called the Mack dealer to see what a reman is usiing this core. I don't put many miles on this truck in a years time. However I would like to pull a pup behind it and adding weight I sure would like the 18 spd. I have and Eaton 13 spd in my road tractor, that has 1.1 mil on it. I bought a RTLO18913 at a salvage yard (as a core) for $2000. It is currently being rebuilt now and I will swap them out sometime in Oct. All total I will have $5500 into it, but will have a spare, working (but worn) 13 spd. If I do the same with the Mack, I will have $6700 into it and a spare, working 12 spd. What is the value of a used TRTXL 1070B 12 spd w/ 240K miles on it???

How much more are these to rebuild, than an Eaton? An Eaton core is $1500, I can get the Mack core for $200.

Looks like the "B" means a faster reverse. I wonder if the standard reverse gears can be put in it during a rebuild?

Thanx for the replies. I was told it was a 13 spd, but it looks like an 18 spd, by model #. It is being sold as a rebuildable core. Am I looking at $3500 to have it rebuilt? Or are Mack transmissions more that Eatons to rebuild? I'm thinking of putting this in a dump truck - good idea or not?? I don't mind the slow reverse.

What can I be told about these transmissions? Are they reliable? Easy to rebuild?? Max torque it can handle. What is the first gera ratio? What is the top gear ratio?