JoeH Posted December 21, 2021 Share Posted December 21, 2021 2003 MR688S, AI-350, Allison HD4560P, 5.32 rears on 315/80R22.5 Top speed? Also, I know Mack makes an air operated and an automatic peanut style power divider. Is there a full open rear tandem setup also? Picture attached. Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/ Share on other sites More sharing options...
0 880joe Posted December 21, 2021 Share Posted December 21, 2021 Probably around 65mph on top speed and yes mack did have full locking rearends Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485643 Share on other sites More sharing options...
0 mrsmackpaul Posted December 21, 2021 Share Posted December 21, 2021 My understanding is no Mack bogie drive is fully open in the power divider area The air operated type of doohickie you mention is to lock the power divider for slippery conditions And yes 65 MPH with out knowing the details of the Allison is probably pretty close Paul 1 Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485644 Share on other sites More sharing options...
0 67RModel Posted December 21, 2021 Share Posted December 21, 2021 From what I could locate on an Allison HD4560P it has a mechanical ratio (torque converter clutch locked) of 0.67:1 in top gear. I assume the AI-350 engine is governed at 2100rpm? I have never seen or heard of using 315 rubber on drive axles but I guess its possible. If so Goodyear lists their 315/80/22.5 tires at 484 rev/mile. With all that being said, on paper your top speed would be between 72 and 73 mph in top gear at 2100 rpm. Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485645 Share on other sites More sharing options...
0 67RModel Posted December 21, 2021 Share Posted December 21, 2021 This is assuming the truck is not speed limited by the computer with rpms to spare..... Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485647 Share on other sites More sharing options...
0 Mark T Posted December 21, 2021 Share Posted December 21, 2021 315s on drives aren't unheard of in the waste industry. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485661 Share on other sites More sharing options...
0 Joey Mack Posted December 21, 2021 Share Posted December 21, 2021 I have done PDI's on many Republic waste trucks. they come with (10) 315 steer tires on them, then at their shop they pull the rear tires off and put them in stock for steer tires, then put cheapass caps on the rear's... jojo Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485663 Share on other sites More sharing options...
0 Mark T Posted December 21, 2021 Share Posted December 21, 2021 Waste Management uses capped 315s on drives. I've seen lots of roll offs and packers from The City like that too. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485664 Share on other sites More sharing options...
0 67RModel Posted December 22, 2021 Share Posted December 22, 2021 15 hours ago, Mark T said: Waste Management uses capped 315s on drives. I've seen lots of roll offs and packers from The City like that too. I assume you mean Erie, PA. I wonder why they would do that considering dual tandem rears running 11R22.5 tires and a drop axle are legal for the gross weight the truck is registered at. My experience with Waste Management is they are crazy budget conscience and always looking for a way to lower operating costs. Capped 11R22.5 drive tires have to be way cheaper than 315s although I have never bought 315 tires. Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485733 Share on other sites More sharing options...
0 JoeH Posted December 22, 2021 Author Share Posted December 22, 2021 (edited) 1 hour ago, 67RModel said: I assume you mean Erie, PA. I wonder why they would do that considering dual tandem rears running 11R22.5 tires and a drop axle are legal for the gross weight the truck is registered at. My experience with Waste Management is they are crazy budget conscience and always looking for a way to lower operating costs. Capped 11R22.5 drive tires have to be way cheaper than 315s although I have never bought 315 tires. A 315 is much more forgiving when run with a flat tire next to it, especially with the constant sharp turning. Also has a lot more ground contact when driving into landfills. And yes this was a trash truck. The main question I had on peanuts is whether "full open" was an option, I have to test it again but I think I got it stuck in the yard with only one wheel spinning. I'd love to have full lockers, but people dont spec them enough for there to be any in used parts yards. Edited December 22, 2021 by JoeH Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485734 Share on other sites More sharing options...
0 Mark T Posted December 22, 2021 Share Posted December 22, 2021 The truck's power divider could just be worn ?? I think on older Mack rears only the 200 series could be made with a cam and wedge type locker (like the power divider) in the center section. Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485751 Share on other sites More sharing options...
0 Joey Mack Posted December 22, 2021 Share Posted December 22, 2021 Air locking power dividers were also in the 92-93 series rears as well.. jojo Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-485752 Share on other sites More sharing options...
0 doubleclutchinweasel Posted January 6, 2022 Share Posted January 6, 2022 You know, now that I think about it, I THINK I jacked up one wheel on a tandem Mack once, put it in gear, and that one tire spun free without trying to move. That truck did NOT have the air locker. So...maybe? Maybe there were full open models? But, I cannot answer that part of the question with 100% confidence. Interesting question, though. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-486631 Share on other sites More sharing options...
0 mowerman Posted January 7, 2022 Share Posted January 7, 2022 i had a R model years ago but it was a 73 and didnt even have a lock switch...they were both limited slip...they might have changed that after awhile..bob Quote Link to comment https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/#findComment-486669 Share on other sites More sharing options...
Question
JoeH
2003 MR688S, AI-350, Allison HD4560P, 5.32 rears on 315/80R22.5
Top speed?
Also, I know Mack makes an air operated and an automatic peanut style power divider. Is there a full open rear tandem setup also? Picture attached.
Link to comment
https://www.bigmacktrucks.com/topic/68953-peanuts-question-and-top-speed-calculation/Share on other sites
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