eshack93 Posted January 18, 2023 Share Posted January 18, 2023 Question for you fellas, I’ve got an tandem dump r model with a 283 Mack and a two stick 6 speed with 4.17 rears. The ol 6 speed is gonna be due some repair pretty quickly and I’m really considering pulling it and putting an 8LL in it. Be nice to have a couple more gears to traverse these hills where I’m at. My question is does anybody have the numbers or can point me in the right direction for the bell housing, clutch and driveshaft I’ll need? I’m assuming all those things would have to change. Thanks in advance Quote Link to comment https://www.bigmacktrucks.com/topic/72242-transmission-swap/ Share on other sites More sharing options...
67RModel Posted January 18, 2023 Share Posted January 18, 2023 Possibly frame crossmember(s) and/or tranny mounts too. I would think the best route to go would be to find an R6XX of the same model year as yours that is factory 8LL and use the VIN number from it. There will be other small details too like the clutch linkage and the cab floor access panel / shift lever boot. Possibly your puff limiter system if you have one is tied into your current Mack tranny. I don't think the Eaton equipped trucks came with the torque limiting valves....not really a big deal though. I have seen this same type of thread many times on here about swapping out a Mack tranny for an Eaton and they seem to never get resolution. It usually just starts out as someone asking what's involved but then we never hear if they ended up doing it and/or what the details involved were. I don't know if its because the guys end up realizing its too much work or if the cost/benefit just isn't there. Let us know what you find out. Quote Link to comment https://www.bigmacktrucks.com/topic/72242-transmission-swap/#findComment-522972 Share on other sites More sharing options...
eshack93 Posted January 18, 2023 Author Share Posted January 18, 2023 I understand that cost benefit. My thoughts were “well it may save money in the long run” but dumping 10 grand into a transmission swap isn’t really a practical solution either. Thanks for the input I’m gonna keep digging Quote Link to comment https://www.bigmacktrucks.com/topic/72242-transmission-swap/#findComment-522980 Share on other sites More sharing options...
JoeH Posted January 18, 2023 Share Posted January 18, 2023 Having driven a tandem axle with the same setup for some years, I would steer you away from a trans swap and into a Jake brake for faster shifts. Your engine makes 90%+ torque across an 800+ rpm powerband. Extra gears are wasted on this engine. The 8LL is designed for engines with a 4-500 rpm powerband. Faster shifts, however, help you catch the next gear while you're still in your 90%+ powerband. You'll also be giving up your multi speed reverse, which let's you crawl up a mountain or fly across soggy ground. But at the end of the day, you know your workload conditions and needs better than me. It should be a doable conversion if you have access to a good Mack junk yard. Quote Link to comment https://www.bigmacktrucks.com/topic/72242-transmission-swap/#findComment-522983 Share on other sites More sharing options...
JoeH Posted January 18, 2023 Share Posted January 18, 2023 (edited) We had to delete the engine brake on our 283 however, because one cylinder has a weak valve spring and the spacer that rests on top of the exhaust valve kept popping loose. After the second time we pulled the Jake off. If you have 50-80,000 hours on your engine like we suspect our has, then you may want to replace valve springs if you add a Jake brake. Edited January 18, 2023 by JoeH Quote Link to comment https://www.bigmacktrucks.com/topic/72242-transmission-swap/#findComment-522984 Share on other sites More sharing options...
j_martell Posted January 22, 2023 Share Posted January 22, 2023 On 1/18/2023 at 12:15 PM, 67RModel said: Possibly your puff limiter system if you have one is tied into your current Mack tranny. I don't think the Eaton equipped trucks came with the torque limiting valves....not really a big deal though. My old 89 RD688S was an E6-350 with an 8LL and had a puff limiter. That random air switch on the dash wasn't tied into it though.....LMAO. Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/72242-transmission-swap/#findComment-523595 Share on other sites More sharing options...
Macktruckman Posted January 16 Share Posted January 16 I see its been a year but did you ever swap or decide on what to do? I ask because ive done this myself Quote Link to comment https://www.bigmacktrucks.com/topic/72242-transmission-swap/#findComment-545179 Share on other sites More sharing options...
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