Any allison gurus in here? - Printable Version
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Any allison gurus in here? - onefaststang1 - 12-12-2024
Our coach (1976) was born with a Cummins 555 and allison mt41 trans.
The 555 is impossible to get parts for so I am planning a heart transplant.
I have a 24 valve 5.9 cummins. That is slightly tuned up. I feel this is going to be a good power plant for the bus with a bump in hp/to over the 555.
I have a couple transmissions I am looking into. The mt41 is not going to handle the torque of the new engine.
I currently have a lead on an mt645cr. Any experts in here that can tell me if this would be a good trans for this swap?
RE: Any allison gurus in here? - cwl1979 - 12-12-2024
I'm no expert on this but i don't believe that would be a good idea. While the 5.9 Cummins is an amazing engine, its much smaller than what you'd be replacing. That old 555 is just that, a large V-8 with 555 cubic inches, the 5.9 is only 360. Id be worried about overheating and overworking it on the daily. Thinner cylinder walls and lowered cooling capacity. If it were me looking to "upgrade" on a repower id probably start looking for a Cummins 400 big cam. You'll probably have to fab new motor mounts either way since you'd be going from a V-8 to an inline 6. Perhaps look for an 8v-92?
As for the transmission you're looking at, its a solid transmission. Coming from a military transport background, its tested and proven.
RE: Any allison gurus in here? - [email protected] - 12-12-2024
(12-12-2024, 07:43 AM)onefaststang1 Wrote: Our coach (1976) was born with a Cummins 555 and allison mt41 trans.
The 555 is impossible to get parts for so I am planning a heart transplant.
I have a 24 valve 5.9 cummins. That is slightly tuned up. I feel this is going to be a good power plant for the bus with a bump in hp/to over the 555.
I have a couple transmissions I am looking into. The mt41 is not going to handle the torque of the new engine.
I currently have a lead on an mt645cr. Any experts in here that can tell me if this would be a good trans for this swap?
I am with Carl on using a 5.9 for a vehicle like this, you are hauling the weight all the time around, in a pickup its only when you are hauling a load. What kind of weight is your coach? I would be looking at a mechanical 8.3 Cummins. We have a Wanderlodge member that bought an entire motorhome for pennies and he re-used the entire frame and running gear to transplant to another coach, but you can find some of these older diesel pusher RV's that are water damaged etc and they can be sold for cheaper than you can pickup the engine and transmission combo. Then you will get a transmission that will already be mated to the engine that will be what you need. Just my 2 cents. I am sure a 5.9 would work, its just not going to have the longevity of a larger engine designed for heavier vehicles.
I am assuming you mean the MT654CR, that is what is in my Wanderlodge. From what I have heard the only weakness in the 6 series of transmissions is the forward clutch was kinda small for pulling heavy loads, this is why they ended up with the 7 series transmissions and they put a larger forward clutch in them.
RE: Any allison gurus in here? - Little - 12-12-2024
As a lifetime Cummins mechanic and warranty rep I too would nix the 5.9. You can easily get the power you need but the torque wont be near what is capable from the 8.3.
Unfortunately the engine you have is probably the worst engine Cummins produced, so whatever you replace it with will be an improvement. You may need to look at an overdrive trans, as the 8.3 runs best at under 1800 rpm.
8.3 is one of the most reliable, fuel efficient engines built. I have a farm tractor (Versatile 555) that we swapped out the 555 with an 8.3.
There should be some scrap stick/staples Rv's with good 8.3 mechanical powertrains. Lots will have under 50k miles. Good luck, you should have the perfect rig when finished.
RE: Any allison gurus in here? - dirtypotato - 12-29-2024
Hello my name is zach im a diesel mechanic although i dont own a motor coach i have experience in allison stuff if your looking for a allison id always recommend a 1000 series i know its a older bus but like the other user said 8.3 with a allison 1000 series be a solid match.
RE: Any allison gurus in here? - cwl1979 - 12-29-2024
(12-29-2024, 03:11 PM)dirtypotato Wrote: Hello my name is zach im a diesel mechanic although i dont own a motor coach i have experience in allison stuff if your looking for a allison id always recommend a 1000 series i know its a older bus but like the other user said 8.3 with a allison 1000 series be a solid match.
While the 1000 series is great in a pickup it cant take the loads from these coaches. These coaches are weighing in at 45k plus pounds. Hence the reason they have 4000 series transmissions in them.
RE: Any allison gurus in here? - dirtypotato - 12-29-2024
cwl im sure they will see the postings but yea a 8.3 ISC is under powered for that kind of weight too if it is 40K. depends on how much space he got in his coach but a series 60 or something with 400+ HP be ideal. The 4000MH needs 650 input power but 3000 series is rated at 450 HP. depending on space.
RE: Any allison gurus in here? - onefaststang1 - 12-29-2024
My coach is no where near 40k. 25-28k is what i am shooting for.
RE: Any allison gurus in here? - Jack Houpe - 12-30-2024
JR how's the interior going? We look forward to seeing your progress and sure this coach will be first class when its done.
I'm a gearhead but not a diesel guru so let me ask this. I had a 5500 topkick that I towed a 50' triple axle car gooseneck trailer with 2 cars and tons of tools in it. The topkick had a Duramax diesel with Allison transmission and been over the Rocky's many times and never did it feel under powered, so what would be the difference of putting something like that into a older coach that is much lighter than our coaches?
RE: Any allison gurus in here? - onefaststang1 - 12-30-2024
(12-30-2024, 05:42 AM)Jack Houpe Wrote: JR how's the interior going? We look forward to seeing your progress and sure this coach will be first class when its done.Slow going. Wife hurt her shoulder so she has been out of commission. A little cold out, but we get a little done when we can.
I'm a gearhead but not a diesel guru so let me ask this. I had a 5500 topkick that I towed a 50' triple axle car gooseneck trailer with 2 cars and tons of tools in it. The topkick had a Duramax diesel with Allison transmission and been over the Rocky's many times and never did it feel under powered, so what would be the difference of putting something like that into a older coach that is much lighter than our coaches?
I don't see why you can't use a duramax. Same thing with the 5.9 cummins. It makes 300hp, probably 5-600 ft lbs of torque. Used in a 10-12000 lbs truck that daily haul trailers with that much weight as well.
I don't think it will be a problem. I have this cummins already, so that is what's going in it. It makes more power, and torque than that v555 ever could.
I have access to this trans as well. It came out of a town truck that a buddy of mine bought with low miles. I van have the trans if I want it. Just trying to make sure it will work in my application.
I need to stay with a somewhat mechanical controlled trans.