NLC Posted December 30, 2018 Share Posted December 30, 2018 I have a b61 with a endt675 engine Tri-plex trans and 6:34 ratio rears. Top speed now about 43 mph at 2100 rpm. What ratio could I go to and Still keep good pulling power and go 60 mph. Pulling a small lowboy and D5 dozer. Quote Link to comment https://www.bigmacktrucks.com/topic/55157-gear-ratio/ Share on other sites More sharing options...
terry Posted December 30, 2018 Share Posted December 30, 2018 I would go with about a 5.13 ratio, is your triplex a single or double over? terry Quote Link to comment https://www.bigmacktrucks.com/topic/55157-gear-ratio/#findComment-412199 Share on other sites More sharing options...
NLC Posted December 31, 2018 Author Share Posted December 31, 2018 Not really sure but I think it’s a single over. Haven’t been able to read the numbers on the transmission so much grease covering it. It has the aluminum box on the back. Quote Link to comment https://www.bigmacktrucks.com/topic/55157-gear-ratio/#findComment-412205 Share on other sites More sharing options...
terry Posted December 31, 2018 Share Posted December 31, 2018 (edited) 1 hour ago, NLC said: Not really sure but I think it’s a single over. Haven’t been able to read the numbers on the transmission so much grease covering it. It has the aluminum box on the back. Right behind fill plug on left side is a flat area, scrape with a putty knife then a wire brush, there will be a TRT72 or 720, that will tell what front box is, back box is always a overdrive on a triplex or quad. terry Also a aluminum back box will be a TRTL series Edited December 31, 2018 by terry Quote Link to comment https://www.bigmacktrucks.com/topic/55157-gear-ratio/#findComment-412209 Share on other sites More sharing options...
NLC Posted December 31, 2018 Author Share Posted December 31, 2018 Thank you for the information. I will check on that tomorrow. Quote Link to comment https://www.bigmacktrucks.com/topic/55157-gear-ratio/#findComment-412210 Share on other sites More sharing options...
Hobert62 Posted December 31, 2018 Share Posted December 31, 2018 My direct drive dueplex has 4.30 and tall tires will run 66mph at 2300rpm Quote Link to comment https://www.bigmacktrucks.com/topic/55157-gear-ratio/#findComment-412214 Share on other sites More sharing options...
Hobert62 Posted December 31, 2018 Share Posted December 31, 2018 (edited) Maybe this will help with some info. Rob has it ln a listing for a engine in the parts forsale section. Edited December 31, 2018 by Hobert62 Quote Link to comment https://www.bigmacktrucks.com/topic/55157-gear-ratio/#findComment-412215 Share on other sites More sharing options...
NLC Posted December 31, 2018 Author Share Posted December 31, 2018 Thanks for the information. Does anyone have the plate that fits between the fender and the hood on a B61? Quote Link to comment https://www.bigmacktrucks.com/topic/55157-gear-ratio/#findComment-412216 Share on other sites More sharing options...
Toller Posted December 31, 2018 Share Posted December 31, 2018 Doing some quick math, if you're doing 43 mph with a 6.34 ratio, you'd need a 4.50 rear to do 60 mph (4.54 technically, but if I recall, Mack made a 4.50 rear that went into some of the Bs with the direct-drive duplex). I'm guessing you have a single-over triplex with final drive ratio of .85. On standard rubber that would give you about 47 mph at 2100, pretty close to the 43 mph you mention. I would think that you have enough power pull a dozer at 60 mph with the ENDT and a 4.50 rear, at least on flat ground. I once drove a single-axle R model with an END 673 (no turbo), single-over triplex, and 4.14 rear pulling single-axle trailers with maybe a 10-12,000 pound payload, and it would run about 70 until it hit a hill. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/55157-gear-ratio/#findComment-412220 Share on other sites More sharing options...
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