d8pete

Paul - I don't hear air leaks of any kind in the cab either when the engine is running or engine shut down. As for the "D8", Caterpillar is my first love and I have always had a great appreciation for the model D8, 1938 to the present model D8T. I have a 1957 D8 14A, its a real work horse and one of my favorite machines to operate. Pete

Terry & mrsmackpaul - I was wondering about the regulator, but I don't have a service manual and wanted to know what you guys out there with more experience thought before I started to change anything. Thanks for your replies. Pete

I have 1984 Mack R model with the TRTXL 1070B tranny. I had the transmission installed a couple of years ago and really love it. My question is when I move the selectair switch the rear compound tries to shift immediately. When I watch others on Youtube go up through the gears they are able to "preselect" the shift of the rear compound and when they move the main transmission lever the rear compound shifts and both the main and rear compound slide into gear easily. It seems with the others something delays the shift of the rear compound until the main transmission shift lever is moved, however it doesn't happen with mine. Any ideas???

Hello Don - Yeah you can say things have been pretty busy - burnin the candle at both ends and a couple spots in the middle. Steve Sabo owns and operates Target Transport and hauls for reasonable pricing. He hauls primarily old equipment and steam engines are right up his alley. He always seems to have a decent backlog of work. I've got him set up to move the D8 as well, but he can't get to it for a few weeks. I'd be all over that 15B but you know it has one big problem - the motor is the wrong color. If your serious about selling it I can put the word out. Now if I could just get this d___ trailer and brake thing behind me I would be in good shape. I've tried every lead I have gotten except yours with no luck. I will try your guy today. Later.

I have a 1956 Rogers lowbed trailer hooked to my R model and I am in need of some brake shoes for the trailer. The trailer has a 12" brake drum and the shoes are 5-3/4" wide. I gave the numbers off the shoes to a local parts supply house and they told me it appeared to be a Rockwell # but didn't have anything available to match up. I have had a few other places looking but noone can seem to help. Is there a good source out there for old brake parts. I could sure use some help on this one.

HK is there a way to test to see if the balancer is faulty and if it is the balancer wouldn't you hear the noise all the time, not just under a load? Thanks, Pete

I have a 1984 R686ST with the 300 and 6 speed and when the truck is under a heavier load/pull or when accelerating hard the engine noise increases quite a bit. Best I can describe it as a general dull pounding noise and is most noticeable at 1600rpm. When empty or pulling on level ground the engine is considerably quieter. The odometer shows about 415,000 miles and at about 1800rpm or better I carry 60 plus pounds of oil pressure hot. When cold the oil pressure is easily over 90 or 100psi. Hot it probably idles at 20 psi and pulling in the low rpms it runs about 30-35psi. So my question is what is normal operating oil pressure for a new and worn engine and how does mack determine when the bearings should be replaced? One friend told me not to worry about the noise and another who was once a Mack mechanic thought I might have a bad or leaking injector causing the noise. Any ideas?

Hopefully this will help illustrate my question if I can get this to post correctly. Thanks again guys for all your input. Mack trans 1.pdf Mack trans 2.pdf Mack trans 3.pdf

fjh and LMACK - I looked last night and the truck has 3.87. Where do I look to find the weight rating of the rearends while we are on the rearend topic? Thanks. Pete

LMACK - How do I tell what rearends I have, is there a marking on the castings somewhere? Like I said before, I love the truck but I just don't think this truck was set up for heavy loads and hills both. 54,000 lbs with moderate grades and I'm fine.

HK - Yes I do stay in my operating range and maybe go down to 1000 rpm. At about 2000 rpm in 4th high my truck is going about 38mph or so the speedometer tells me. 5th high takes me from about the 38mph to 72mph at 2050rpm. When downshifting from 5th high to 4th high I have to get the truck down to 35-39mph with the brakes and no Jake and once I'm in 4th the motor is already on the top of the rpm range and provides little braking action to hold back the truck and trailer, so once again the brakes do all the work. Thats why if there was a split or another gear between 4th and 5th it might be easier. Just my two cents. Hi Chuck - yes Jeff Moyle told me about Al Smith's passing. I saw him at Bowling Green and he looked pretty good. Very sad, the Mack and Cat guys lost another great supporter and great friend. Pete

Thanks guys for the replies - I am only a novice truck driver at best and do it only for my hobby which might explain part of my situation. However looking in the Mack manuals for the trxl 107 mack states that the use of low range in 2,3,4,5 is not recommended as the ratio of 3rd in high is the same as 4th in low, 4th in high is the same as 5th in low,and the same for the lower gears. I love having 5 reverse speeds but when accelerating heavy or climbing a gradual grade the step from 4th to 5th is a little long and with no Jake trying to downshift to hold yourself while going down a long grade is difficult. Randy I will try and post some pictures of my truck and trailer with the Cats. Caterpillar wise I have a 10,22,30,40,60 D2,D6,RD-6,and RD-7. Like I'm sure you've heard before I'm one of the guys that likes to play with Cats and Dogs. Pete

I have a 1984 R686ST with the 300 and 6 speed 2 stick transmission. I love the truck and use it to haul my antique caterpillars for my hobby. My question is why does the 6 speed have so many repetitive gear ratios? Why were they not set up like the duplex to allow split shifting and have 10 different ratios available? I told a friend once, if I designed a 10 story building but told the owner he could only use 6 floors, I don't think I would be designing buildings for very long. It seems as though the step from 4th to 5th is quite far? I would appreciate any info. thanks.