Licensed to kill Posted March 29, 2021 Share Posted March 29, 2021 Are there faster gear sets available for the B-61 diffs, something in the 3:40 range?. I would like to keep the "Mack" script diff housing but want a faster gear ratio. Quote Link to comment Share on other sites More sharing options...
Vladislav Posted April 9, 2021 Share Posted April 9, 2021 Is your truck a single axle or a tandem? Tandem B's utilized (in the most cases) the same style carriers as later models did such as CRD92 and CRD93. So plenty of different ratio diffs could be swapped in. Sorry no help with single axles. Quote Никогда не бывает слишком много грузовиков! leversole 11.2012 Link to comment Share on other sites More sharing options...
Brian L Blaylock Posted April 9, 2021 Share Posted April 9, 2021 If it’s a single axle I think a 4.00 gear ratio is about as fast as you will find 1 Quote Link to comment Share on other sites More sharing options...
Freightrain Posted April 10, 2021 Share Posted April 10, 2021 Ya, 4.00 is all I have ever seen listed. They didnt have the power to gear them any faster, plus the speed limit was only 45 mph. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted April 10, 2021 Share Posted April 10, 2021 We used to joke about the non-turbo 673s in the B-61s we had. Seems they would run about as fast downhill as they would uphill. Not very. 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
Licensed to kill Posted April 11, 2021 Author Share Posted April 11, 2021 Mine are all single axles units. I guess i will be looking for a complete swap. thanks for the info. Quote Link to comment Share on other sites More sharing options...
h67st Posted April 11, 2021 Share Posted April 11, 2021 22 hours ago, doubleclutchinweasel said: We used to joke about the non-turbo 673s in the B-61s we had. Seems they would run about as fast downhill as they would uphill. Not very. I read online a while back that a guy drove a 673 duplex back in the day, he said you needed all 10 gears because a toothpick would pull the thing down! Quote Link to comment Share on other sites More sharing options...
RRJordan Posted April 11, 2021 Share Posted April 11, 2021 In the mid-1950s I drove a badly worn and overloaded LF with a Lanova a little and on upgrades passed couple senior drivers proud of their new B-63s. I was strongly warned never to do that again! 1 Quote Link to comment Share on other sites More sharing options...
Maddog13407 Posted April 12, 2021 Share Posted April 12, 2021 what motor and trans and what are you wanting to do with the truck? im runnin a 711 and single over triplex and a 4.00 rear on 11 24.5 s and it will cruise 75-80 bobtail but put a trailer on it and it will remind you what you have.... 1 1 Quote Link to comment Share on other sites More sharing options...
Licensed to kill Posted April 12, 2021 Author Share Posted April 12, 2021 (edited) I have a 283/5spd out of an '80 gravel truck that i am planning on running. Only planning to pull my 5th wheel holiday trailer with it which is not very heavy. Was thinking to get a gear that would put me close to peak torque at 100KPH (60 MPH) so around 1200 RPMish for best fuel economy. Will be running 11R22.5's. I assume that the trans is direct in 5th but need to confirm that yet. Edited April 12, 2021 by Licensed to kill Quote Link to comment Share on other sites More sharing options...
Freightrain Posted April 12, 2021 Share Posted April 12, 2021 I would suggest sliding an air ride under the back with a faster gear. Give you the best of both worlds. That spring ride will beat that travel trailer to pieces! Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
Licensed to kill Posted April 13, 2021 Author Share Posted April 13, 2021 15 hours ago, Freightrain said: I would suggest sliding an air ride under the back with a faster gear. Give you the best of both worlds. That spring ride will beat that travel trailer to pieces! Yup, that's the plan. Since it appears that I will be changing out the entire diff, I will just use one that already has air ride. Otherwise i was going to add it to the old diff. Quote Link to comment Share on other sites More sharing options...
Freightrain Posted April 13, 2021 Share Posted April 13, 2021 I met a fellow 20 yrs ago right after I got my truck. He had a new set of springs made for the rear with only 3 main leaves. He too pulled a travel trailer with it. I did similar by just having my spring pack cut down to 3. It worked well with my race trailer(only 3000# on the pin) until I finally did stretch my truck and add the air ride. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
Popular Post Freightrain Posted April 13, 2021 Popular Post Share Posted April 13, 2021 On 4/10/2021 at 11:42 AM, doubleclutchinweasel said: We used to joke about the non-turbo 673s in the B-61s we had. Seems they would run about as fast downhill as they would uphill. Not very. My buddy(ex driver) used to say it was a Rolls Canardly. Rolls down hill fine, but can hardly make it up the other side. 2 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
Licensed to kill Posted April 18, 2021 Author Share Posted April 18, 2021 I am assuming that the 5spd has a direct high gear. If so, I would need a pretty tall rear to achieve the cruising RPM I was thinking of and that may compromise 1st gear and reverse (way too fast). So, based on my engine/trans (1980 283/5spd) and my intended purpose (pulling a holiday trailer) what would be a suitable rear gear with 11R 22.5 tires the would keep cruising RPM down to a dull roar? Quote Link to comment Share on other sites More sharing options...
Mark T Posted April 18, 2021 Share Posted April 18, 2021 What you're trying to accomplish may require a different rear gear and an overdrive transmission . Quote Link to comment Share on other sites More sharing options...
Licensed to kill Posted April 18, 2021 Author Share Posted April 18, 2021 I have been considering adding a splitter box Quote Link to comment Share on other sites More sharing options...
Rob Posted April 18, 2021 Share Posted April 18, 2021 I would install a 3.70 ratio rear on Neway ARD suspension as they are plentiful, and inexpensive. Sure lower, gearing will work also as you will have plenty of available engine power, but the pricing seems to skyrocket with the later model preferred gearsets and suspensions. I don't think you'd have problems with a 2.43 ratio but the cost...... Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
Licensed to kill Posted April 18, 2021 Author Share Posted April 18, 2021 2.43 would be pretty good but i would be concerned about reverse being way too fast. Just a guess as I have no clue what the reverse gear ratio actually is. Something in the 2.80 range (don't know what actual ratios are available) should put me at about 1400RPM @ 60mph which would be pretty good IMO, again, reverse ratio might be an issue. Quote Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted April 19, 2021 Share Posted April 19, 2021 Like I told somebody on another thread, remember there are overdrive versions of those Maxitorque transmissions. And, the 6-speed version adds a lower gear to boot. And, you get 5 reverses. Plus, you end up with 2 sticks, like God intended in a Mack! Check out a TRXL-1070. Or, you could go the masochistic route and put in a 13-speed Triplex or 18-speed Quadruplex. Those are both "double-overdrive" boxes. And, the lo-lo or lo-split reverses are plenty low. 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
Licensed to kill Posted April 19, 2021 Author Share Posted April 19, 2021 I look at the one i have and could not find any number resembling TRXL-1070. All I know about it is that it came behind a 283 in a 1980 and is twin stick. Having said that, I thought they ALL were twin stick with the extra low gear in the auxiliary box and that some called them 5 spd for the main box and others called them 6spd including the aux box but were talking about the same trans. I didn't know that some came with OD. Is there a number on it that would tell me for sure what I have?. Quote Link to comment Share on other sites More sharing options...
Mark T Posted April 19, 2021 Share Posted April 19, 2021 There's one extended range that's a five speed with a second lever, but the high in the second lever only works in the main in 4th and 5th ? IDK what model it is, but one of those and 4.17s ??? It'll have some top end then (lol) Quote Link to comment Share on other sites More sharing options...
terry Posted April 20, 2021 Share Posted April 20, 2021 7 hours ago, Licensed to kill said: I look at the one i have and could not find any number resembling TRXL-1070. All I know about it is that it came behind a 283 in a 1980 and is twin stick. Having said that, I thought they ALL were twin stick with the extra low gear in the auxiliary box and that some called them 5 spd for the main box and others called them 6spd including the aux box but were talking about the same trans. I didn't know that some came with OD. Is there a number on it that would tell me for sure what I have?. Yours is probably a T107X, i think that is the right designation, a five speed main with a direct and low and reverse on the other stick. the TRXL 1070 is actually 3 boxes bolted together, the front is direct and low, then a five speed main, and then a direct and hi splitter. the dirtect and low can be a air switch on the dash or a second stick for the earlier ones, and the reverse and direct/hi split is on the shifter. and if this is not confusing enough, some early ones were a TRXL 107 witch did not have overdrive, direct all the way through in top gear. terry I once had a DM dump dump with that TRXL 1070 with 4.17's and it was a real runner. 1 Quote Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted April 20, 2021 Share Posted April 20, 2021 I don't exactly know what boxes y'all are talking about. Might have been later versions. But, there was a 5-speed with a single stick (TRL-107 series). Then, there was a 6-speed "extended range" with 2 sticks (TRXL-107 series). The "lo" on the compound was supposed to be used only in 1st gear. That's your extra low gear. Here is graphic showing some detail on the ones I am talking about. The TRXL-1070 (or maybe it was a TRDXL-1070) would have been the same as the TRXL-107, but with "direct in 4th", and an overdrive 5th. The "0" on the end of the number is the "overdrive" designation. Model numbers were on the left side of the box. There are several discussions on here that have pictures showing the location. Somebody on here had the one I am talking about (TRDXL-1070). Check out this link. https://www.bigmacktrucks.com/topic/56848-mack-trdxl-1070-questions/ 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
terry Posted April 20, 2021 Share Posted April 20, 2021 (edited) Yeah weasel it can be pretty confusing. you are right on the TRXL 107 6speed that is the one i was talking about when i said T107X, and that TRDXL 107 6 speed was a forerunner of the TRXL 107 series. and the TRXL 1070 or 12 speed is another variation yet! On the TRDXL 107 it was a 5speed main with a direct and low back box, the TRDXL 1070 was a 5 speed main with a direct and overdrive back box. real clear now!😂 terry Edited April 20, 2021 by terry Quote Link to comment Share on other sites More sharing options...
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