1960 B61, Customer wants modern trans & rear to acheive normal roadspeeds.

[DIALSDIESEL]

Any tips, pointers, ideas or learning experiences to share? This truck belongs to a customer of mine, (he just bought it) he wants to get rid of the "15 speed triplex" and put in a 7 or 9 speed, also this truck has the double reduction rear end. he claims it will not exceed 45mph on the highway. it was in a barn for 17yrs and only has 39,000 miles on the odometer, beleive it or not the truck really does only look like it has 39,000!

hope to hear from you all soon. thanks, Allen.

[daveigou]

We have a rule here, no pictures=no advice. Seriously, if the guy wants to make it really driver friendly, and he is not offended by using non-Mack components, I would use a Fuller 9 spd., "B" ratio, and gear the rear end up with a single reduction rear in the 4.1 something range. That will give good startability and good road speed. All this stuff should be reasonable and readily available.

[Freightrain]

Depending on how it was built, it could have 5.xx gears out back which would really slow the truck down. Finding fast gears(4.10 or such) will be tough for that carrier. I think 4.00 was the fastest they made back then.

My 4.10(air ride) and single over triplex gets me 72 mph on 22.5 rubber. I would not want a 7-9 spd for a low power truck. You'll really struggle to get up to speed(especially if you pull a trailer). If you don't want two sticks, maybe a 10 or 13 spd RR. When I bobtail, I start in 3 Lo and skip along to 4th lo. Then I start splitting as it takes a bit more umph to build more speed. Especially on the highway, if you don't have a nice split ratio it will be a dog on the hills.

My .02, since using mine for pulling my race trailer all summer for the last 12 yrs.

[Maddog13407]

yup, no pics, no advice haha, i have said that before along with others. also location?

[DIALSDIESEL]

Thanks for the info thus far.

Whats the best way to post the pics?

[Freightrain]

Use Photobucket or some hosting site. Then copy/paste the link.

[Superdog]

It makes me wonder,especially since he wants to get rid of the Triplex,if in fact he is shifting it right??45 mph would be about right for 5th direct.Someone not familiar with the way a Triplex shifts,would not be used to the aux. pattern(around the corner then up to the dash)especially if they were only used to a modern transmission shift pattern.Just a thought.

[607t1173]

If you are determined to remove the Triplex in order to increase your road speed try an RTO 15 speed it's a .78 O.D. and with the deep reduction feature you will have the best of both worlds also it's so much quicker and easier to shift, the Mack engine responds very well with this swap especially in the hills. You'll lose the aesthetics of two sticks which to the purist is nothing short of blasphemy but you will definitely improve the driveability.

If it was mine and had 39K actual verifiable miles I would try to upgrade the differential and would leave the transmission as is.

[607t1173]

I should probably elaborate further as to why a RTO 15 Speed I have personally done this swap a number of times using the RTO 915 and RTO 12515. They are relatively inexpensive and still found in alot of older trucks you'll need to buy the transmission bellhousing with provisions for motor mounts but you'll have a much more "novice friendly"truck to drive.

I think Superdog hit the nail on the head with his answer. Most and I emphasize the word Most people aren't proficient in properly shifting this transmission as you can see on You tube

[Joe Ditchkus]

Changing to single overdrive Fuller is not going to increase speed much or any at all. Triplex is overdrive in near same % as Fuller 15 speed. To get double overdrive he would have to use double over 13 speed. No such trans as a double over 10 or 15 speed.I cannot understand why a B-Model with factory tri-plex would have rear ratio lower than hi 5.00'S. Tri-plex was used mostly for road work tractors not off road unless it was tri-plex used in B-53'S and a few other B-Models that had deep reduction gearing like a Quadbox not progressive gearing. It was said 15 speed so it is progressive trans. Joe D.

[David]

What engine is in this truck and how it's it going to be used? If it's a hobby truck and never going to be loaded, use aT200, 5,6,7 or 8 speed. With .6 overdrive you'll have good highway speed but never get it in high loaded.

[Joe Ditchkus]

You might get away with an 8 speed but since this is not a high torque rise engine RPM spreads in trans with less gears would cause lugging a no no in 673 Thermodyne.Joe D.

[David]

Thats why I wondered how it was going to be used.

[607t1173]

I'm aware that a RTO isn't going to increase his road speed but he had mentioned a 7 or 9 speed trans and I have always found the 15 spd Fuller makes the best and most driver friendly choice. If they were to put a later model rear differential (as he stated) in it they can choose the ratio that they think they need and with the deep reduction they'll have the ability to use a 3:70 or maybe a 3:90 or even a 4:11. As for a RTOO 13 speed Fuller transmission,many years ago I bought some mixers with NTC 230 Cummins and RTOO 13 speeds and we eventually changed them over to 8LL's and sacrificed speed (running empty) for pulling power when( we were loaded) in the hills. If he was using the truck for anything other than a hobby truck the only time he'd ever get a 13 double over Fuller mated to a END 673 in double over would be going down a hill. The later model 18 Speeds are great with the double over but I doubt that he would want to spend the bucks that it would take for that conversion. The ones I've got are running behind 550 Cats and even with that much torque it's hard to run in double over if you're grossing close to 80K .

In what state was this barn find located?

[DIALSDIESEL]

Got my daughter to help me. Here's the first few.

[2stacksuperdog]

Looks in very nice shape

[Maddog13407]

omg is that thing nice and original and sweet. dont put a RR in her or cobify her! she will cry. i cannot for the life of me see that thing only doing 45 MPH with an overdrive triplex unless it had about an 8.49 ratio rear end

[2stacksuperdog]

omg is that thing nice and original and sweet. dont put a RR in he or cobify her! she will cry. i cannot for the life of me see that thing only doing 45 MPH with an overdrive triplex unless it had about an 8.49 ratio rear end

I agree. Too nice to de-Mack it

[Reuhlz]

omg is that thing nice and original and sweet. dont put a RR in he or cobify her! she will cry.

I would agree. Way too nice of an original to modify.

[Maddog13407]

yup. if he wants to Demack one, i could trade or sell him a few mutts i have for that pristine one!

[felicello122]

This is a very nice original unit' leave her alone' I would add some rear fenders.

[607t1173]

I must agree that to make ANY changes to this original, pristine, perfect example of an iconic truck with only 39K miles would be shameful.

PLEASE DO NOT CHANGE A THING

Consider seeing if your customer will put a price on it cause I'm sure that someone on this sight (me included) would be willing to make a premium offer for this rare truck.

[607t1173]

I just noticed the phone # on the door and thought that this truck must've belonged to another Georgia native by the name of Junior Samples.

[607t1173]

If this is the truck that I think it is I had an opportunity to buy it in the late 80's or early 90's

[607t1173]

If this is the truck that I think it is I had an opportunity to buy it in the late 80's or early 90's I feel fairly certain that I do know this truck and if you'll look at the sign on the door it say's Jersey,Ga.. The guy that bought this truck new was from Jersey and had moved to Ga. in the 80's. The truck was restored in the early 90's and was a real nice one owner example at that time I'm almost certain that it's not a 45 MPH truck.

In the early 90's I sold the original owner and his brothers a couple of dumptrucks for use in their landscape supply business.

I'll be back in Ga. next week and will come by and drive it if you want and we'll find out how it's really geared.