HK Trucking

A manual transmission in a car is "synchronized" meaning that when you shift it, you simply depress the clutch and move the shifter to the next gear. The synchronizers in the transmission "synchronize" the 2 sliding "clutch gears", to enable a clashless shift. An unsynchronized transmission has no synchronizers, and the engine RPM's must match the road speed of the gear you're trying to shift into. To achieve that, you can double clutch, or shift it without using the clutch depending on your skill level,making sure that the engine RPM's are at the same level as if the transmission was already in the gear you're shifting into. As long as the engine RPM's are correct for the gear you're shiftinginto, the shift will be smooth, if the RPM's are incorrect, it ain't going into gear. .

It's a very good transmission. The TRL 1076 is the same as the triple countershaft TRL107, except that one countershaft has been omitted. The case is the same as the triple countershaft TRL107, it's just that one countershaft isn't there. Regarding shifting, It's one of the simplest and easiest shifting transmissions out there. Anyone who can comprehend the principles of shifting an unsynchronized transmission will be able to shift it just fine. .

Better look closer. To my knowledge, Mack never made a "P61". .

Actually, I believe that the first character in that serial # is a "B", as in "B61T11947, indicating that it is a B61 single axle tractor. A "P" if it were for "platform" designation, would follow the "61" in the serial number, not precede it.

Sounds to me like maybe the puff limiter is stuck, not allowing the rack to open up fully. Every one of those 866 engines that I've seen ran like hell. I recall a time when I was driving a Brockway with a 425 Cat engine and a 13 speed, and another guy that worked with us was driving an R700 with a ENDT866 and 12 speed. There was a long hill on RT 22 in NY state that had 2 lanes going up the hill, trucks were supposed to stay in the right lane. I was following the R700, we were both pulling Fruehauf trailer dumps loaded equally with bank run gravel. Going into the hill, I got on the Cat motor as hard as I could,and pulled out into the left lane to see if I could pass the R700. The Brockway pulled about even with the R700, and then it was a stalemate, I couldn't outpull that 375 HP Mack with the 425 Cat, and believe me, I was on that Cat motor for all it was worth. .

When we lived out in the country, my old lady and the kids were always monopolizing the bathrooms, so I put my own shitter on the front porch. When ya gotta go, ya gotta go!! And..... If you look closely, there is "duck tape" on the screen door! .

A power steering box from any of the R600's from that era should bolt right in. The R models usually used a TRW/Ross integral P/S unit. You'll also have to get the pump and oil tank, and make up the necessary lines to connect it all. Some of the early R models used a combination pump/tank unit which was belt driven at the front of the engine, off the crank pulley. A 1977 would have the spline driven pump attached to the rear of the air compressor, with a separate oil tank mounted at the right front of the frame. If using the spline driven pump, you'll need to pull the back cover off your compressor and make sure the end of the compressor crankshaft is set up to accept the p/s drive adapter, and you'll also need the pump mounting adapter that bolts to the rear of the compressor and has the mounting flange where the pump bolts on. Of these 2 setups, I prefer the spline driven pump if possible. .

We'll need to know exactly what model your 77 Mack dump truck is to answer that question. .

It's stamped in the frame rail, right where Larry said. If the frame is dirty or rusty you'll need a scraper, wire brush and some sandpaper to make it readable. .

Keep in mind that the operating range of your engine is 1200 to 2100 RPM. As long as your RPM's are in that range, it's all good, hence the wide spacing between the gears RPM wise. .

Yes, although the TRXL1071 6 speed did have a couple "splittable" ratios (not recommended by Mack) such as shifting from 2nd lo to 1st direct with 2 hands. That was the TRDXL 1070. .

Is the air pressure actually low while the buzzer is on, or is the air pressure normal (105 - 120 PSI)while the buzzer is on? That would help us to narrow it down. .

He's lucky he wasn't DEAD after that! Same thing happened around here about 15 years ago, a guy was driving a DM600 triaxle down HWY 41 and he must have left the PTO engaged, and the up/down lever must have got into the up position. The story I heard was that a guy in a concrete mixer was running alongside the triaxle waving to the driver that the dump body was up. Apparently the dump driver thought the mixer driver was just waving "hello" because he kept right on driving. When the mixer guy noticed that the Meade St. overpass was coming up ahead, he stepped on it to get ahead of the dump truck and not get involved in the impending crash. Anyhow, the dump body hit the overpass at highway speed, and was ripped off the truck and came to rest in the road. The driver was hurt pretty bad, but did survive. I never got a close up look at the damage to the truck, but the company that owned it did repair it and put a new dump body on it, as I saw that particular truck back on the road not too long after. Them DM's are indestructible! .

Doesn't matter. If you've got a bad sensor it may be telling the ECM that there is low or no oil pressure, high coolant temp, or low coolant level, depending on which sensor is defective. .

Well, there is a health benefit to that used 85w90 also. It is high in iron and other important metals. You found that container at a truckstop fuel island? Hope it wasn't a pee jug!!!!!!!!!!!! .

Good to see that you're using "synthetic". Much lower in calories & cholesterol. That'll help to keep your blood pressure down while you're driving that Peterbilt. .

Trunnion bushings. The rest all depends on whether you've got the bronze greasable bushings or the rubber bushings. If you give your VIN # to your Mack dealer they should be able to look it up and see just what you've got. It's heavy work changing trunnion bushings and unless you've got the large jacks, jackstands, 1" impact wrench, cutting torch etc, you're better off having it done at a Mack dealer or a suspension shop.

Regarding the difference in piston top configuration, I recall seeing a Mack service bulletin back around the mid 90's discussing that change, and the fact that more combustion "rattle" would be noticeable in engines fitted with the new design pistons. I put a set of those updated Mack pistons into a 237, and also put a set in a 285 back around that time and never had any problems with them. But that's when Mack parts were still being made by Mack and not subcontracted to some low bid company in India. Perhaps V*lv* has subbed out all the Mack replacement parts manufacturing to 3rd world sweatshops. .

Another way of thinking about it: The engine needs to be at the same RPM as it would be at if you were already in the gear you're trying to shift into. Once that is achieved, the transmission will slide into gear effortlessly without even using the clutch. .

I hope you realize that once you transplant those International tanks, your truck will need to be on "anti rejection" medication for the rest of it's life. .

For your reading pleasure: http://www.bigmacktrucks.com/index.php?showtopic=3355 .

Is the stick physically jumping out of the gear positions, or does the stick stay "in the hole" but the trans seems to jump out of gear? If the stick is staying in the hole, yet the trans seems to be jumping out of gear in low range, then the low side of the range shift synchro has taken a dump. Common problem on the T200 series transmissions.

I'll second that!!!!!!!! .

A '93 RD688S could be either mechanical or elec. I had a 91 RB688S that was mechanical,it would leave a C12 430 H.P. Cat in the dust. Also had a '95 CL with a mechanical E7 350 in it. The fact that the RD in your post has a 400 HP engine suggests to me that the "8 speed" is a Eaton Fuller 8LL. The 8LL is a great dump truck transmission, it has a deep reduction for heavy off road startability, and also has a .73 overdrive in hi gear for decent road speed.

Heavy Metal "brain damage" type music is my first preference, I'll listen to that when I'm driving or by myself. In the shop I usually listen to an "oldies" station or classic rock, so as not to get the boss & co workers annoyed. .