luke andres Posted April 3, 2017 Share Posted April 3, 2017 ill be at the shop tomorrow where my book is ill see what i can do i have never posted a pic before but have been wanting to so this might be a good learning experience 1 Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366256 Share on other sites More sharing options...
Casper1988 Posted April 3, 2017 Author Share Posted April 3, 2017 Kinda leaning towards a 12 speed Mack tranny. I will try to get the ratios on a 12 and see. Thanks all. Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366262 Share on other sites More sharing options...
j hancock Posted April 3, 2017 Share Posted April 3, 2017 12 speed OD is .78 ratio. Low is 14.44. At 1800 rpm, you will be at 60 mph with 5.02 gears and 24.5 rubber. Dropping down to direct will be 47 mph. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366264 Share on other sites More sharing options...
luke andres Posted April 3, 2017 Share Posted April 3, 2017 13 speed mack tranny od is .71 low is 13.91 your 2070 tranny is od .60 low is 14.16 the 2070 will run faster and have a slight lower low gear my 2080 had a low of 20.08 and od of .60 with 5.73 gears I could start out loaded on a 60 degree incline and not burn the clutch not a good tranny for the road thou in my opinion 1 Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366290 Share on other sites More sharing options...
terry Posted April 3, 2017 Share Posted April 3, 2017 4 hours ago, luke andres said: 13 speed mack tranny od is .71 low is 13.91 your 2070 tranny is od .60 low is 14.16 the 2070 will run faster and have a slight lower low gear my 2080 had a low of 20.08 and od of .60 with 5.73 gears I could start out loaded on a 60 degree incline and not burn the clutch not a good tranny for the road thou in my opinion After about third gear you need a splitter with the six,seven and eight speed trans in this series. terry Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366305 Share on other sites More sharing options...
luke andres Posted April 3, 2017 Share Posted April 3, 2017 totally agree i dont care what engine or horsepower you have too big of a jump between gears Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366307 Share on other sites More sharing options...
TeamsterGrrrl Posted April 4, 2017 Share Posted April 4, 2017 Luke, you ever seen the power curve for Maxidyne? Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366308 Share on other sites More sharing options...
luke andres Posted April 4, 2017 Share Posted April 4, 2017 no Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366309 Share on other sites More sharing options...
luke andres Posted April 4, 2017 Share Posted April 4, 2017 I put the information about the Tranny on the BigMackTrucks.com facebook page. You may reference the photo there under the visitors section in the right hand column. Unfortunately I was unable to attach any photos to this forum or gallery. Input on how to correct the issue is appreciated. Thank you, Luke 1 Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366312 Share on other sites More sharing options...
Casper1988 Posted April 4, 2017 Author Share Posted April 4, 2017 Went to the shop yesterday to get oil, this is a well known shop in my area and talked to a Mack guy who has 30 plus years experience. really confused now, he said the 12 speed is big long and expensive to fix if there are issues with it . So he thought a 9 speed would be a good match up. Everyone does have a opinion on whats best for a swap out, still gathereing info and next will be to find some trucks locally and see what there running. I did take it for a ride yesterday after oil in the rears and king pin job, went real nice. Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366332 Share on other sites More sharing options...
Casper1988 Posted April 4, 2017 Author Share Posted April 4, 2017 So, what about changing up 4 and 5th gear in this tranny, could that be a possible solution instead of a different transmission. Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366333 Share on other sites More sharing options...
TeamsterGrrrl Posted April 4, 2017 Share Posted April 4, 2017 Luke, a conventional diesel engine produces peak power at 2100 rpm and maybe 90% of peak power at 1600 or so rpm, so a 9 or more speed transmission is needed. A maxitorque produces peak power at 1700, and at least 90% of peak power from 1200 to 2100, thus as little as 5 speeds are needed. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366383 Share on other sites More sharing options...
Casper1988 Posted April 4, 2017 Author Share Posted April 4, 2017 I have some time driving and shifting many different types of eqiupment around the farm (20 plus years ). I would say this 2070 is not the most easiest transmission to dial in but I am also in no hurry to get anywhere loaded. Once I drop the load though that .60 overdrive will get me home quick. Good advice on this site. Thanks all. Quote Link to comment https://www.bigmacktrucks.com/topic/49341-changing-up-my-transmision-in-my-1988-r-690s/page/2/#findComment-366385 Share on other sites More sharing options...
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