snowcombine

No not yet still planning the swap. Was hoping to avoid the wiring issue I was thinking about an E9 but I don't need 500 Hp or repair bills since I need to pencil in a future rebuild. Our 430hp cat in the COE has no problem pulling the b-train anywhere we go even out of a soft field at harvest time.

Yeah I could, but 400 powered R models with the old style hood aren't real common. The ones I have seen are all new style hood R with a 20000# front axle(kinda heavy for a tractor) or are ch models. So I may have to do a bunch of work to get what I want.

Have been thinking about this for a while. I looked through almost all of the pages regarding engine swaps. If I understand correctly a mechanical e7 350 or 400 will replace an e6 without too much trouble providing the front of the engine has the right configuration. So I was thinking could I put an e7-400 with a t2180(that is the model # for an 18sp right?)into my 1980 RD685 with 38000# 4.42 rears. Would the rears handle it or would I need 44s? there is an 89 R model with 44s coming up at an auction but I haven't seen it yet. Would the 89 be a better choice for this kind of swap? The biggest loads I pull are a triaxle double drop hauling my farm equipment between farms(up to 100,000lbs. max) and a five axle super b grain trailer (140,000lbs gross). I currently pull this with a 435 horse 3406e cat. Would I miss the 35hp and 100lbs of torque?. Have thought about finding a superliner with an e9 but would rather have a regular R model if I could.

Mike; Certainly no offence taken. I definitely do understand your frustration with shows and "hey everybody vote for mine" BS that goes on. Our local car club has figured out a way around it that has been working well. Like the other guys said I'm not into shows the truck is just a workin' machine. Parts aren't really a problem partly because it doesn't get many miles and doesn't break down! As for being my favourite, It runs smooth, pulls the load well(I even hauled 140,000lbs once, a bit much but it did OK)The cab doesn't rattle near as much as our other trucks, doors close with a gentle push. I just use it for what it is meant for. Besides, it's as close as I will probably get to having a vintage heavy truck.

finally got around to getting a picture of our truck on here. It's a 1980 RD685S 237 6 speed Have owned it since '89. First as a straight truck with a grain body for the first ten years then converted to a tractor as the farm grew. Have had a KW and Freightliner but our Mack is definitely the favourite!

Thanks I thought the rears would be more than just housings. I am finding it hard to find a 350 powered truck and am thinking about a swap as the local wrecker has a couple including a 12 speed to go with it. My old mack operators manual lists both a 2valve head and a 4valve head engine with different torque and hp specs. The 2 valve peak tq is at 1400rpm and power at 1950rpm.The 4 valve is torque at 1250 rpm and power at 1800 rpm . It doesn't say what the Torque actually is, but I am assuming the 4valve engine is the one to go for with my loads? With 11-24.5 rubber, 4.17 axle ratio, and the 12 speed OD at .78 it works out to 1650 rpm at 60 mph. would this be a good cruise rpm? the book says best fuel economy at a rpm less than that or should I care?

Our 237 has a 4.17 ratio and in deep reduction it has no trouble starting the load. So I was thinking that since the 12 speed has a similar deep reduction ratio the 350 would probably do just fine. It would be nice to have the rpm a 100km (62.5 mph) a little lower but I guess that is the trade off. Also I was told that the only difference in mack 38 and 44 rears was the housing, and the internals are the same. any truth to that?

I am looking for another R Model tractor for pulling our grain trailer and equipment trailer. Would a 350 & 12 speed handle 140,000 pounds or should I be looking for an E9? We don't have much for hills ( don't have to shift down ever with a 435 cat 18 speed) Our 237 six speed will almost handle the load but it is pretty hard on the truck. Any thoughts?

Hi everyone we farm in north central Alberta and have a 1980 RD685s 237-6 spd bought in '89. Was first set up with a grain dump body, now pulls a tandem hopper trailer. Still looks good and runs great have a freightliner as our main truck now but want to replace it with another Mack! Just found this site while looking for some info.