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MCI 102-C3 coach to RV - Chassis/Suspension

MarkObtinaro said:
When you suggested a wheel lift for towing your toad I was hoping you were going to say you were going to rework the back end of the bus first.

Unless it is a school bus with a frame that goes all the way back to the rear bumper there are very few buses that have the strength to carry any weight on the back bumper--no structure other than the body sheet metal to support the tongue weight and no structure to withstand the pulling.

I saw GM bus that had been converted to an RV that hit a bump on the highway hard enough that the toad pulled the power package out of the back of the bus. The rear end of the bus was sitting on the ground and the engine, transmission, rear end was about twenty feet behind the bus with the toad still hitched to the rear bumper.​
I should have mentioned frame reinforcement, but decided to suggest the fab work discussion wait for later because of the amount of explanation. The nice thing about Pirate is you can actually get that to work. Posting that anywhere else will send commenters on a tangent that bite your head off and never answer your question!
 
02rexwi said:
This would be a nice rear axle for you: https://www.govplanet.com/for-sale/Parts-Axletech-050175-Automotive-Driving-Axle-Assembly-Pennsylvania/2626312?h=5000,m|AxleTech&rr=0.5&hitprm=&pnLink=ye s
Originally came on a BAE RG31. Might be a little light for what you're building, but it's got the right wheel bolt circle and tons more ground clearance.​
I've been looking over the Pierce/Oshkosh Tak-4 stuff again -
https://www.govplanet.com/for-sale/Parts-Oshkosh-3822375-Right-Rear-Axle-MRAP-Unused-Pennsylvania/2595530?h=5000,q|oshkosk&rr=0.02326&hitprm=&pnLink =yes&reloadCode=stall,1568975697000,1569022811231
https://www.govplanet.com/for-sale/7-Ton-Cargo-Trucks-2003-Oshkosh-MK23-MTVR-7-Ton-6x6-Cargo-Truck-California/1952739?h=5000,m|Oshkosh&rr=0.33333&hitprm=&pnLink =yes

Not exactly what I would like to use, but they come up often and don't appear to be as sought after as Axletech. I would be more tempted if I could get disc brake versions that don't have Rzeppa cv's. Rzeppa's are always my preference on other vehicles. On a bus equipped with military suspension, though, replacing Rzeppa parts would be hell as opposed to double-cardan that uses a relatively standard u-joint. I'm still poking around for some Axletech 4500's while we have a bit of time.
 
02rexwi said,
JNHEscher said:
I've been looking over the Pierce/Oshkosh Tak-4 stuff again -
https://www.govplanet.com/for-sale/Parts-Oshkosh-3822375-Right-Rear-Axle-MRAP-Unused-Pennsylvania/2595530?h=5000,q|oshkosk&rr=0.02326&hitprm=&pnLink =yes&reloadCode=stall,1568975697000,1569022811231
https://www.govplanet.com/for-sale/7-Ton-Cargo-Trucks-2003-Oshkosh-MK23-MTVR-7-Ton-6x6-Cargo-Truck-California/1952739?h=5000,m|Oshkosh&rr=0.33333&hitprm=&pnLink =yes

Not exactly what I would like to use, but they come up often and don't appear to be as sought after as Axletech. I would be more tempted if I could get disc brake versions that don't have Rzeppa cv's. Rzeppa's are always my preference on other vehicles. On a bus equipped with military suspension, though, replacing Rzeppa parts would be hell as opposed to double-cardan that uses a relatively standard u-joint. I'm still poking around for some Axletech 4500's while we have a bit of time.​
They may seem like "relatively standard" universal joints in the Axletech u-joints, but I think you'd have a hard time finding them in the aftermarket.
 
02rexwi said:
They may seem like "relatively standard" universal joints in the Axletech u-joints, but I think you'd have a hard time finding them in the aftermarket.​
I'll take a look again. I thought I had come up with with the AT u-joint specs that matched a standard joint while vigorously jotting down notes over the winter. Did some more digging for TAK-4 specs. Only place I found a manual was on that scribd site. I suppose it'll be worth the $8.99 for a month to grab all I can. I did see enough of the manual to confirm that they do not have planetary hubs which is a bummer.
 
02rexwi said,
JNHEscher said:
I'll take a look again. I thought I had come up with with the AT u-joint specs that matched a standard joint while vigorously jotting down notes over the winter. Did some more digging for TAK-4 specs. Only place I found a manual was on that scribd site. I suppose it'll be worth the $8.99 for a month to grab all I can. I did see enough of the manual to confirm that they do not have planetary hubs which is a bummer.​
The TAK-4 from a MTVR is planetary. VERY similar to an Axletech 5000
 
02rexwi said:
The TAK-4 from a MTVR is planetary. VERY similar to an Axletech 5000​
Man,... anything and everything you got on TAK-4 info would highly appreciated. Pictures, thoughts, literature, etc. I've yet to lay my hands on any AxelTech, Oshkosh or Meritor assemblies, so I'm learning them all via internet. I have no idea what gear ratios they contain or what the gear assemblies are like. The auction on govplanet said the TAK-4 pallet weighed quite a bit more that an AT 4500 (edit: 4,000ish lbs. vs. 2,300ish?).

Edit: So I did miss the "planetary wheel end" label in the pictures here - https://www.siddons-martin.com/wp-co..._March2018.pdf
That TAK-4 on govplanet was brand new and sold for $505! I would still really like to find a parts breakdown before getting serious about bidding on the next one that pops up. Disc brakes are still preferred just because of their simplicity, but for a price similar to that last assembly that sold, I'd take drums.
 
arse_sidewards said,
JNHEscher said:
Man,... anything and everything you got on TAK-4 info would highly appreciated. Pictures, thoughts, literature, etc. I've yet to lay my hands on any AxelTech, Oshkosh or Meritor assemblies, so I'm learning them all via internet. I have no idea what gear ratios they contain or what the gear assemblies are like. The auction on govplanet said the TAK-4 pallet weighed quite a bit more that an AT 4500 (edit: 4,000ish lbs. vs. 2,300ish?).

Edit: So I did miss the "planetary wheel end" label in the pictures here - https://www.siddons-martin.com/wp-co..._March2018.pdf
That TAK-4 on govplanet was brand new and sold for $505! I would still really like to find a parts breakdown before getting serious about bidding on the next one that pops up. Disc brakes are still preferred just because of their simplicity, but for a price similar to that last assembly that sold, I'd take drums.​
That "tension rod" style torsion bar setup is pretty cool. Looks like it gives you a middle ground between solid axle and totally independent.
 
02rexwi said,
JNHEscher said:
Man,... anything and everything you got on TAK-4 info would highly appreciated. Pictures, thoughts, literature, etc. I've yet to lay my hands on any AxelTech, Oshkosh or Meritor assemblies, so I'm learning them all via internet. I have no idea what gear ratios they contain or what the gear assemblies are like. The auction on govplanet said the TAK-4 pallet weighed quite a bit more that an AT 4500 (edit: 4,000ish lbs. vs. 2,300ish?).

Edit: So I did miss the "planetary wheel end" label in the pictures here - https://www.siddons-martin.com/wp-co..._March2018.pdf
That TAK-4 on govplanet was brand new and sold for $505! I would still really like to find a parts breakdown before getting serious about bidding on the next one that pops up. Disc brakes are still preferred just because of their simplicity, but for a price similar to that last assembly that sold, I'd take drums.​
At $505 that's a steal. That's all the information I can give.
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arse_sidewards said:
That "tension rod" style torsion bar setup is pretty cool. Looks like it gives you a middle ground between solid axle and totally independent.​
It does look neat. I wasn't expecting to see a torsion bar style spring on such a large IFS assembly. I'm still after a drive axle assembly for all three positions.
02rexwi said:
At $505 that's a steal. That's all the information I can give. <a href="http://www.pirate4x4.com/forum/images/smilies/smile.gif" border="0" alt="" title="
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" >
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</a>​
Hmmm. Sounds like I'll be the one to spill the beans if I acquire either a TAK-4 IRS or ProTec 50. The AT 4000/4500 still appears to be the simplest of them all. Typical R&P, locker hub, halfshafts and the tried and true spur-cut planetary hubs. The diff on the TAK-4 looks similar to a 2-speed center. That'd be kinda cool, but are they really 4,000 pounds? From what little info I could gather about them, their overall gear ratio isn't much different than AT.
 
02rexwi said,
JNHEscher said:
It does look neat. I wasn't expecting to see a torsion bar style spring on such a large IFS assembly. I'm still after a drive axle assembly for all three positions.




Hmmm. Sounds like I'll be the one to spill the beans if I acquire either a TAK-4 IRS or ProTec 50. The AT 4000/4500 still appears to be the simplest of them all. Typical R&P, locker hub, halfshafts and the tried and true spur-cut planetary hubs. The diff on the TAK-4 looks similar to a 2-speed center. That'd be kinda cool, but are they really 4,000 pounds? From what little info I could gather about them, their overall gear ratio isn't much different than AT.​
I'd love to spill the beans, but keeping a job is a priority :laughing:
I'll keep an eye out for units that come on the market.
 
02rexwi said:
I'd love to spill the beans, but keeping a job is a priority
I'll keep an eye out for units that come on the market.​
Lol. Had a hunch. Just save me the employee discount code.

I'm going to keep watching for TAk-4 units, but if they are indeed 4,000 pounds each, I may go ahead with some AT 4000's.
 
jd8420 said,

Make sure the TAK-4 axles aren't too wide. I think the ones in the Oshkosh MK23 may be ok but the airport crash trucks that have them are probably too wide to be legally driven down the highway. Most of those have at least 24R21 tires and there is a long ways between the tires. I bet they are around 10' wide if not wider. The Oshkosh MK23 have 16.00R20 tires and look like they are probably around 8.5' track width. I believe the transfer case in the Oshkosh MK23 is overdriven but they have the Cat C12 of C13 that likes lower RPMs than the trucks that the AT4000's come in so they are probably about the same gear ratio. I bet the crash trucks are pretty low geared though because they usually don't get up much speed and are weighted really heavy.
 
jd8420 said,
02rexwi said:
At $505 that's a steal. That's all the information I can give.
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The part # on that one is 3822375. Can you tell from that what the WMS to WMS is? What about the overall gearing?
 
jd8420 said:
Make sure the TAK-4 axles aren't too wide. I think the ones in the Oshkosh MK23 may be ok but the airport crash trucks that have them are probably too wide to be legally driven down the highway. Most of those have at least 24R21 tires and there is a long ways between the tires. I bet they are around 10' wide if not wider. The Oshkosh MK23 have 16.00R20 tires and look like they are probably around 8.5' track width. I believe the transfer case in the Oshkosh MK23 is overdriven but they have the Cat C12 of C13 that likes lower RPMs than the trucks that the AT4000's come in so they are probably about the same gear ratio. I bet the crash trucks are pretty low geared though because they usually don't get up much speed and are weighted really heavy.​
I thank you, sir. Nowhere else have I been able to gather info such as that. I figured I'd be best off to avoid the crash truck units. I read through a forum that gave me little insight to their gearing, but I would much prefer a manual reference. The member stated that the pinion is about as big as the ring with a 1.7:1 ratio and the planetaries are between 2 and 3:1. No info on width. That govplanet auction stated the pallet weight was 4k lbs. which is a hell of a lot.
 
jd8420 said:
The part # on that one is 3822375. Can you tell from that what the WMS to WMS is? What about the overall gearing?​
I searched it high and low. Came up bone dry. From what I understand, the manufacturer and contracted users of the units want it that way for now.
 
jd8420 said,

Oshkosh Defense says the Oshkosh MK23 has a overall width of 98". So you should be ok with width.

They weigh about 28,000 pounds though so the axles may be 4000 pounds each.
 
jd8420 said:
Oshkosh Defense says the Oshkosh MK23 has a overall width of 98". So you should be ok with width.

They weigh about 28,000 pounds though so the axles may be 4000 pounds each.​
The weight poses some other problems. On the upside, maybe it would help keep the COG low. I do wonder if the drum brake versions can accept the disc brakes without modification.
 
02rexwi said,
jd8420 said:
The part # on that one is 3822375. Can you tell from that what the WMS to WMS is? What about the overall gearing?​
I can't help you out much with Oshkosh part numbers. If you have Axletech questions I can share a limited amount of info.
 
02rexwi said:
I can't help you out much with Oshkosh part numbers. If you have Axletech questions I can share a limited amount of info.​
Where'd all the AT 4500's go? That's what I wanna know. We would set up the trip to go get three units if I knew of any at a reasonable price. The TAK-4's might be geared better, but for what I want to do, the AT ratios make for more torque from a smaller drive.
 
02rexwi said,
JNHEscher said:
Where'd all the AT 4500's go? That's what I wanna know. We would set up the trip to go get three units if I knew of any at a reasonable price. The TAK-4's might be geared better, but for what I want to do, the AT ratios make for more torque from a smaller drive.​
The bulk of the 4500 independent suspensions that were made in North America have gone to the Canadian military. The production volume of 4500 ISAS axles was small compared to many of the other military programs, so it makes sense that there aren't many popping up in the aftermarket.

If you could get your hands on one of the most recent ones from a Commando Elite you'd have a pretty nice platform for that bus.
 
02rexwi said:
The bulk of the 4500 independent suspensions that were made in North America have gone to the Canadian military. The production volume of 4500 ISAS axles was small compared to many of the other military programs, so it makes sense that there aren't many popping up in the aftermarket.

If you could get your hands on one of the most recent ones from a Commando Elite you'd have a pretty nice platform for that bus.​
I got some hints towards them being shuffled to Canada a while back. The AxleTech Offroad page was passed on to Western Candian Rockwell, so I asked AxleTech Offroad if they knew of any 4500 units available because they were the last place I spotted that had some in their inventory, but those units were for another customer. They said they didn't know of anymore availbe either.

Whatcha know about Cammando Elite? Google gave me action figures and a movie.
 
jd8420 said,
JNHEscher said:
02rexwi said:
I can't help you out much with Oshkosh part numbers. If you have Axletech questions I can share a limited amount of info.​
Where'd all the AT 4500's go? That's what I wanna know. We would set up the trip to go get three units if I knew of any at a reasonable price. The TAK-4's might be geared better, but for what I want to do, the AT ratios make for more torque from a smaller drive.​
https://www.ebay.com/itm/Maxxpro-MRA...MAAOSww3Ndi785
 
bdkw1 said,

Wonder if that is for both axles? And the T-case? I think I stopped in that place last time I was down there.
 
bdkw1 said:
Wonder if that is for both axles? And the T-case? I think I stopped in that place last time I was down there.​
Both axles, tires and t-case. Sweet deal, but maybe more than we want to deal with and the 5000 ISAS might be just as heavy as the TAK-4. 12,000 pounds in axles is almost what our bus weighs as it currently sits.


Edit: adding some thoughts-

I stared at the pictures on the eBay listing for a while. The 5000 ISAS tops out at 3,340 lbs. Not bad. Especially since I'm able to strip some weight. The bus would still ride on air, so all four coil springs can go. I'd bet one coil weighs more than a pair of the air bags. Unless the plate assembly is absolutely needed, that can go and possibly shed maybe 150 pounds. If the top plate goes, the shock uppers will mount to the bus frame. Dropping this weight seems like I could get it down much closer to the 4500 series weight.

For now, I'm running RPM and torque specs using a TM4 (now partnered with Dana) SUMO HD3500 direct drive motor which I can explain later. Max RPM of 3,400. The listed AT 5000 unit has an overall ratio of 9.344:1. This brings the max road speed to 45 MPH on a 315/80-22.5. No good. The good, though, is that it puts the same amount of torque to the wheels as the Detroit with the Allison and 3.33 Rockwell. Ultimately, I plan for a drive motor for each axle, so torque doesn't have to be that high, and the motors could be smaller with higher RPM capacities.

Another downside is the width. 90.3-97.8 inch WMS to WMS. I don't know the width of the listed unit. Too wide for legal limits, even with the maximum 2" positive offset in the wheels, but the fun part is that the diff can be lifted high enough at ride height to pull the wheels in to fit the width limit of 102". Doing so would cause the laden wheels to stick out a bit in corners, kinda helping handling a bit.

The inboard brakes are cool with some uncool. Way more braking power than would be necessary, but an easy way to lessen the force is to possibly swap out the type 24 service chambers for some 18's. Same mounting is available.

I probably have more. These are my thoughts for tonight. Just got back from Missouri tonight and I'm beyond tired. Off to Oklahoma City on Tuesday. Only 4 hours from Springfield, MO. Maybe, just maybe, I can go check out the AT 5000's if they haven't already sold. The price kills it, but I'll see what happens.

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02rexwi said,
JNHEscher said:
Both axles, tires and t-case. Sweet deal, but maybe more than we want to deal with and the 5000 ISAS might be just as heavy as the TAK-4. 12,000 pounds in axles is almost what our bus weighs as it currently sits.


Edit: adding some thoughts-

I stared at the pictures on the eBay listing for a while. The 5000 ISAS tops out at 3,340 lbs. Not bad. Especially since I'm able to strip some weight. The bus would still ride on air, so all four coil springs can go. I'd bet one coil weighs more than a pair of the air bags. Unless the plate assembly is absolutely needed, that can go and possibly shed maybe 150 pounds. If the top plate goes, the shock uppers will mount to the bus frame. Dropping this weight seems like I could get it down much closer to the 4500 series weight.

For now, I'm running RPM and torque specs using a TM4 (now partnered with Dana) SUMO HD3500 direct drive motor which I can explain later. Max RPM of 3,400. The listed AT 5000 unit has an overall ratio of 9.344:1. This brings the max road speed to 45 MPH on a 315/80-22.5. No good. The good, though, is that it puts the same amount of torque to the wheels as the Detroit with the Allison and 3.33 Rockwell. Ultimately, I plan for a drive motor for each axle, so torque doesn't have to be that high, and the motors could be smaller with higher RPM capacities.

Another downside is the width. 90.3-97.8 inch WMS to WMS. I don't know the width of the listed unit. Too wide for legal limits, even with the maximum 2" positive offset in the wheels, but the fun part is that the diff can be lifted high enough at ride height to pull the wheels in to fit the width limit of 102". Doing so would cause the laden wheels to stick out a bit in corners, kinda helping handling a bit.

The inboard brakes are cool with some uncool. Way more braking power than would be necessary, but an easy way to lessen the force is to possibly swap out the type 24 service chambers for some 18's. Same mounting is available.

I probably have more. These are my thoughts for tonight. Just got back from Missouri tonight and I'm beyond tired. Off to Oklahoma City on Tuesday. Only 4 hours from Springfield, MO. Maybe, just maybe, I can go check out the AT 5000's if they haven't already sold. The price kills it, but I'll see what happens.​
Those 5000 series MAXXPRO axles would be SWEET. Overall ratio on those is more like 6.57:1
They don't show the ID tag for the axle, so I can't tell you what the wheel end planetary ratio is, but I've got a good idea.

At design ride height width between hub faces is probably 97.8"; again, a guess until I see the ID tag. You're right, you could jack up the height to suck that in.

Info on the commando elite: https://www.textronsystems.com/produ...amily-products
 
GLTHFJ60 said,

IMO, i think you're dreaming about the axles. I can't imagine that a vehicle that large would be able to get anywhere offroad, or that the chassis would stand up to the flexing stress that would put on it.

Get the camper usable, with all the features you want on the inside, then eval the axles/suspension later after you have some miles on her.
 
arse_sidewards said,
GLTHFJ60 said:
IMO, i think you're dreaming about the axles. I can't imagine that a vehicle that large would be able to get anywhere offroad, or that the chassis would stand up to the flexing stress that would put on it.

Get the camper usable, with all the features you want on the inside, then eval the axles/suspension later after you have some miles on her.​
Busses will get stuck if you even think about driving them on wet grass. The guy with the bloodmobile sunk his in like the first hundred feet off road or something like that. I think having three driven axles will help immensely in all the "not off road but not on road either" situations a camper finds itself in.
 
02rexwi said:
Those 5000 series MAXXPRO axles would be SWEET. Overall ratio on those is more like 6.57:1
They don't show the ID tag for the axle, so I can't tell you what the wheel end planetary ratio is, but I've got a good idea.

At design ride height width between hub faces is probably 97.8"; again, a guess until I see the ID tag. You're right, you could jack up the height to suck that in.

Info on the commando elite: https://www.textronsystems.com/produ...amily-products​
6.57:1 is about right for the max motor RPM. What does the 1.42 mean on the data tag? I was assuming the 1.42 - 6.58 was a separate listing for the planetary and diff ratios.
GLTHFJ60 said:
IMO, i think you're dreaming about the axles. I can't imagine that a vehicle that large would be able to get anywhere offroad, or that the chassis would stand up to the flexing stress that would put on it.

Get the camper usable, with all the features you want on the inside, then eval the axles/suspension later after you have some miles on her.​
We're in pursuit of a dream, my good man. 15.x" of wheel travel is definitely impressive on a bus, but suspension flex isn't a big deal to me. The main purpose of the swap is to have all three axles driven and double-wishbone suspension is pretty sweet.
arse_sidewards said:
Busses will get stuck if you even think about driving them on wet grass. The guy with the bloodmobile sunk his in like the first hundred feet off road or something like that. I think having three driven axles will help immensely in all the "not off road but not on road either" situations a camper finds itself in.​
Bingo. I have now seen countless pictures and videos of buses getting stuck in the most ridiculous ways. Numerous bus owners parking in family/friend yards and getting stuck, having to call a wrecker to pull them off the grass. The last two videos I saw were of a Greyhound getting stuck in a Flying J Express driveway because of a big dip that dropped out the drive axle and another of a tri-axle Class A or whatever that couldn't get out of a campground drive because of a big dip. They surely had no problem descending the slope because they could easily control their speed with the brakes on all three axles. But when it came to drive back up with an open diff in a single axle, that's all she wrote. I'm not shooting for hitting mud holes or anything. Just getting ALL the traction on ice, snow, dirt, rocky BLM grounds on plenty of hills and everything in between. I watched some video of a crew taking their RV's into BLM land in Buena Vista. They had to stop so many times to shove rocks under their drive axle tires to get it up there.
 
02rexwi said,
JNHEscher said:
6.57:1 is about right for the max motor RPM. What does the 1.42 mean on the data tag? I was assuming the 1.42 - 6.58 was a separate listing for the planetary and diff ratios.​
I missed the picture of that ID tag. 1.42 is the carrier ratio, 6.58 is the overall ratio.

@ design ride height you're sitting right under 98" hub flange to flange.

The front axle in that set has a limited slip differential, the rear is an air actuated differential lock.

Too bad they're looking for $8500.
 
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