Thoughts on surviving in a C5500 super C? NP205s seem a lot easier to find than a NP273C and a built one is half the price. Any thoughts on this? I know 205s are legend with four wheelers, even behind a high performance motor with some kind of low range/doubler in front of it, but this is going to be living in a higher gvwr/gcwr.
NP205 in a Topkick?
- Thread starter blu88
- Start date
I don't think it was ever used in anything heavier than a 3500, atleast can't seem to find otherwise. As a comparison, it looks like Dodge and Ford uses a NP271/3 in everything from a 2500 to 5500.
Supersingles are the only thing I may run in the future. and it would be the shortest f rated tire out there (40"?) And 6k pounds of weight in the form of flatbed, camper and boxes. My C5500 crew cab weighs about 7k lbs as a cab and chassis. So looking at 13K on a trip, and maybe pulling 7k of trailer.
billiebob
Well-known member
If that were the case the F600 4x4 would have used the 203/205 TC, since the F250/350/600 came with the same engines. But Ford put a heavier TC in the F600.
85_Ranger4x4
Well-known member
When jumping eras remember a one ton ain't a one ton. A 1975 F-350 is different than a 1999 F-350 which is different than a 2020 F-350.
A modern F-150 would give a '75 the thrashing of its life and make the '99 really nervous.
I don't think Ford was that enthused with the 205, they didn't run them for very long compared to Dodge and GM. They jumped to aluminum chaindrives pretty quick. I suspect weight (the 205 is 130lbs dry) and NVH had something to do with it. I notice a lot more drivetrain vibration with mine and with the mount on the t-case my powertrain can't really move anymore... so the truck moves with it.
GM ran them longer but IIRC after '79 only for cab chassis trucks. Was it because they were stronger? Or strong enough and PTO capable?
The 205's 2:1 low range is kinda meh for what that is worth but you can work around that with enough $$. I have mulled regearing/doubling mine but I really don't want to pull the heavy thing back out and put it back in. Plus it is pricey.
If you run a married t-case there may be some idiosyncrasies mounting the t-case to the trans despite the bolt pattern being the same because of the difference in age. I had to notch the flange for the RWD shift rail, notch the bottom for the countershaft nut and made a spacer ring because the boss for on the t-case that goes inside the transmission was too big.
That is as close as they would come together:
So I basically drew the gasket on CAD and had a local fab shop burn me one out of 3/8" plate.
They are supposed to be very tough, are very fun to rebuild and I love the one in my Ranger... but yeah I would do some research for what you are doing.
Twin stick is awesome and cheap to DIY BTW.
+1. More weight means the powertrain strain. It isn't as easy for the tires to slip and give when needed.
1stDeuce
Explorer
+1 more...
I think the worst case for a transfer case in a heavy vehicle with a long wheelbase is simply turning in 4wd. Even on gravel or dirt, there is going to be a LOT of windup between the front and rear drivelines, which would ideally travel at different speeds in a turn, but are locked together by the transfer case. It's amazing the difference between my regular cab and extended cab trucks in 4wd. The reg cab turns much more easily, and needs to slip tires noticeably less than the extended cab does. Our 4wd crew cab dually brush fire truck will pretty much stop if you try to turn sharply in 4wd even on a gravel surface.
I had been considering making my C60 dump truck 4wd for a while, as I used it in the winter for snow plowing in our community, with plenty of hills. It's low power, so I wasn't worried about cooking the t-case, or snapping a shaft with torque, but I was really worried about binding in turns, since the wheelbase is long and the truck is pretty heavy. To combat the binding, my plan was to use a 203 divorced case. That way I could leave it unlocked in most conditions, which would preventing any binding and ease turning, and if I got hung up somewhere and it was only spinning a front or rear, I could lock it in at that point and hopefully escape.
In the end, I found reduced tire pressure, a bit of weight at the back of the bed, and occasionally a set of tire chains sufficient to get the job done.
As for large truck t-cases, you might consider using an air shift transfer case out of a M35 A2 or A3... I believe even the A3 was divorced mount, and it has synchronized shifting, so you can shift the truck trans to N, and shift the transfer case between high and low range at any reasonable speed. Low range is 2:1, but that's usually plenty low for larger vehicles with transmissions that also have lower "low" gears. The air shift engages/disengages the front axle, and you could probably convert it to cable actuation. Additional bonus is 2wd low, for tight maneuvering without bind.
Just a thought...
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broncobowsher
Adventurer
As stated, severe traction and drivetrain loads from the shear mass that it can be can make for huge stresses between front and rear axles. Even with a low power engine. The 205 would look like a toy under a topkick. People do still break 205s, not often but it can be done, and in trucks smaller than a topkick.
Thanks for the replies. Reliability is of the utmost in this build.
I thought about looking for a transfer case from a deuce. Higher gvwr but the multi fuel engines don't produce as much power, and they are physically heavier and bigger. A stock duramax produces a lot more tourque (and double the HP). My crew cab C5500 weighs over 6k right now, with no bed. Adding a flatbed and 4x4 running gear, plus a camper will push me up over 12k. then towing a 6-7k trailer and/or flat towing a vehicle..... my GCWR will probably never top 26k but it would be nice to do whatever I want with it, reliably
So I guess I will keep looking for a 273C, and all the other parts for a 4x4 swap. I do have a front high pinion passenger drop dana 70
I thought about looking for a transfer case from a deuce. Higher gvwr but the multi fuel engines don't produce as much power, and they are physically heavier and bigger. A stock duramax produces a lot more tourque (and double the HP). My crew cab C5500 weighs over 6k right now, with no bed. Adding a flatbed and 4x4 running gear, plus a camper will push me up over 12k. then towing a 6-7k trailer and/or flat towing a vehicle..... my GCWR will probably never top 26k but it would be nice to do whatever I want with it, reliably
So I guess I will keep looking for a 273C, and all the other parts for a 4x4 swap. I do have a front high pinion passenger drop dana 70
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