kahall82 Posted December 15, 2012 Share Posted December 15, 2012 Hi all,I have a 320 Cool power R-model. At the moment it has a two stick 5 speed transmission but I think the 2nd stick is just for lo-lo. And drives very slow...but has 354 welded on the diff housing.I have the chance to grab a Eaton 18spd double overdrive from a 1994 International Transtar. Will this make my truck faster and more for highway travel?I am just waiting on the model number of the box. Have read that double overdrives went out in the 80s but yet have had plenty of people tell me they are the go.Thanks for any info Quote Link to comment Share on other sites More sharing options...
Lmackattack Posted December 15, 2012 Share Posted December 15, 2012 Yes a double over will give you faster road speed. To be certain you need to check your rear end ratio and do the math with the 18 speed ratios. Quote Link to comment Share on other sites More sharing options...
bullhusk Posted December 15, 2012 Share Posted December 15, 2012 Hi all,I have a 320 Cool power R-model. At the moment it has a two stick 5 speed transmission but I think the 2nd stick is just for lo-lo. And drives very slow...but has 354 welded on the diff housing.I have the chance to grab a Eaton 18spd double overdrive from a 1994 International Transtar. Will this make my truck faster and more for highway travel?I am just waiting on the model number of the box. Have read that double overdrives went out in the 80s but yet have had plenty of people tell me they are the go.Thanks for any info Is it an older R model? Cause Mack also made a trans like that, with OD an could only shift the side stick in 5th for over drive Quote Link to comment Share on other sites More sharing options...
oilburner Posted December 15, 2012 Share Posted December 15, 2012 Well like the other guy said find out your ratio, if it is slow it is not a 3.54, that thing would fly with that high of a gear, a double overdrive is a good tranny if you have alot of engine or just don't haul much. When you make a trans double over you losse you low ratio, because you flip the gears on the countershafts and it makes each gear higher. If it were me i love the 15 speed overdrive with a mack engine, you have a deep reduction in the trans giving you 5 low gears, but not as low as frist in a six speed mack, and tight ratio going up in the gears, but that's just me, some people like super 10's which to me are useless, but they do have the biggest overdrive you can get in a single over trans in a eaton that is. I would not recomend a double overdrive unless you ratio is in the 500 range or so, you would probley never get it in the big hole loaded. Quote Link to comment Share on other sites More sharing options...
rsb502 Posted December 15, 2012 Share Posted December 15, 2012 that thing might fly with a 3.54, if it has 11r 22.5's and a direct trans the 3.54 that only makes about 69mph at 2000rpm, with a .73 od it jumps to 94 @2000rpm all 18 spds have 2 od gears and most people consider that a double overdrive, the older eaton double od trans and flipping an eaton to get double od will get you a .64 od gear I think and you will have 4 od gears in a flipped 18spd. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment Share on other sites More sharing options...
rsb502 Posted December 15, 2012 Share Posted December 15, 2012 oh and with lo pro 22.5's that makes a mere 59mph @1800rpm go to a .73 you get 80 Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment Share on other sites More sharing options...
oilburner Posted December 15, 2012 Share Posted December 15, 2012 Yeap that sounds about right, our international 9370 has 3.55 with low pro 24.5 and a 9 speed direct and it does about 82 mph at 2400, but that is a old big cam 4 400, Quote Link to comment Share on other sites More sharing options...
oilburner Posted December 15, 2012 Share Posted December 15, 2012 Yeap that sounds about right, our international 9370 has 3.55 with low pro 24.5 and a 9 speed direct and it does about 82 mph at 2400, but that is a old big cam 4 400,And i am pretty sure the maxi touqe 13 speed has two overdrive gears to, but not a double over, the 13 speeds when fliped actaully have 3 over drive ratio, to make it a double over because when you split 10th to go to 11th you were in direct in 10th then you split it with the back box and 11th 12th and 13th are overdrive ratios, i thank anway correct me some one if i am wrong. Quote Link to comment Share on other sites More sharing options...
kahall82 Posted December 16, 2012 Author Share Posted December 16, 2012 Hi,OK now it has 354 welded on the housing. But I have always had in my mind that they are 5.17 in there. I will have to go to the yard and check. Thanks for the infoGear RatioEighth H 0.73Eighth L 0.86Seventh H 1.00Seventh L 1.17Sixth H 1.38Sixth L 1.62Fifth H 1.95Fifth L 2.29Fourth H 2.73Fourth L 3.20Third H 3.74Third L 4.38Second H 5.16Second L 6.05First H 7.30First L 8.56Lo H 12.29Lo L 14.40 Quote Link to comment Share on other sites More sharing options...
rsb502 Posted December 16, 2012 Share Posted December 16, 2012 And i am pretty sure the maxi touqe 13 speed has two overdrive gears to, but not a double over, the 13 speeds when fliped actaully have 3 over drive ratio, to make it a double over because when you split 10th to go to 11th you were in direct in 10th then you split it with the back box and 11th 12th and 13th are overdrive ratios, i thank anway correct me some one if i am wrong.yeah 13 and 18 have two od gears they are both based on an od 9 speed main box with an underdrive rear box, so in the case of the 13 if you removed the back box it would be 1.1 in 8th and .73 in 9th and with the back box its 1.1 in 8th high and .73 in 9th high like the chart above, if you do a gear flip you actually give it 4 od gears as the 1.1 drops down one whole gear in the main box so it would be 1.1 in 7th high, .86 in 8th low .73 in 8th high .68 in 9th low and .62 or .64 somewhere in there in 9th high of course this is all from memory so I may be off a hair or two. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment Share on other sites More sharing options...
fjh Posted December 17, 2012 Share Posted December 17, 2012 Just be awear you will need to buy a bell houseing! the binder housing will likly not have the mount ears for the mack install and the clutch fork for the mack is upside down for the cable clutch ,there are Quite a few conciderations to think on when doing one of these swaps also there are or were two shiftlid configs on an eaton trans a foward mount and a rear mount stick opening! A couple of inches can make the install easy or hard when dealing with the stick opening on the floor ! Been there done that!Just some stuff to think on Quote Link to comment Share on other sites More sharing options...
rsb502 Posted December 18, 2012 Share Posted December 18, 2012 Just out of pure curiosity did you get any numbers off the trans in your truck? Im pretty sure one of us could give you a better idea of the rpm drop if any you would get out of the swap if we knew which trans you had, then we would know what your top gear ratio is. And have you thought obout keeping it all Makc and finding a Mack OD trans to drop in, it would make it an easier swap for sure, something like a t2090 or trtxl1070. the 2090 would give you a .68 od the trtxl makes it a .78od Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment Share on other sites More sharing options...
SLEEPER DOG Posted December 24, 2012 Share Posted December 24, 2012 Anyone know which RTO 13 was used on a mid 70s R712 ETAZ (300+). Was it a 9513 or a 12513?Wayne Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.