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MCI 102-C3 coach to RV - Chassis/Suspension

We're back and I'll catch up this eve.
David Tillett at ITP got back to me on Friday about the torque converter ratio. Ours is a TC496 which is a 1.78 that shifts at 2100/2250 RPM.


Alright, so I managed to read through your reply during a fuel stop on Friday, @O2rexwi. I was kinda hoping you would throw your knowledge at this one. I'm quite familiar with driveline setups on most vehicles. Your'e correct about the torque converter. Just need the info on the t-cases and AT4K planetary sets, so here is goes...

The t-case preference is the T800 with a 0.80:1 high gear and 50/50 bevel gear center diff. No idea what the prices or model numbers are for that t-case option setup or if that combo is even an option to find anywhere in the market. I haven't been able to find any other pictures of the T800 t-case than what Axletech shows on their sites. One case shown has four flanges. Four flanges on the T800 might allow for one case to operate all the axles, though I don't mind having to run two t-case to do so if they only have an input and the front and rear outputs.

To manage highway wheel speed on commercial tires that have something close to 486 revs per mile, I have to know if the AT4K planetary wheel end ratios can be changed without spending months tracking down what might be a unicorn of a gearset six to eight times because the 3.55:1 set that appears to be the most common the the narrow and wide axles for sale is certainly not going to work. The only other Axletech combination remedy that I'm currently aware of would be to stack t-cases so that the overdriven high gear drops the overall ratio enough.

With 0.80:1 case and 1.58:1 diff = 2.64:1 wheel end
With 0.90:1 case and 1.58:1 diff = 2.34:1 wheel end
With 1.00:1 case and 1.58:1 diff = 2.11:1 wheel end

With 0.80:1 case and 1.92:1 diff = 2.17:1 wheel end
With 0.90:1 case and 1.92:1 diff = 1.93:1 wheel end
With 1.00:1 case and 1.92:1 diff = 1.73:1 wheel end

What I have not yet found out is if the four-pinion gear set ratio is changed with just the sun gear and planetary gears or if the sun, planets, and the ring hub have to be swapped. I've been punching in Axletech keywords on eBay for almost a year now and have only seen a few sun gears and planet plates, as far as 4K wheel end internals. If any of those above (or close to) wheel end ratios and T800 in my preferred trim are available, the t-case option is a doable. I believe I still have the number to call the Axletech guy. Problem is that he almost always has to be given a part or model number. If anyone has the list of wheel end ratios that cover those between 1.73ish and 3.55, gimme.
Edit: I may have the ratio question answered here - https://www.axletech.com/at-admin/re...etterweb-1.pdf 3.22:1 wheel end looks to be the highest.

Using the tandem axles really hasn't been of much interest. No steer option and I would like to avoid cutting up any of the axles because the narrow and wide steers already fit just right.
 
jd8420 said,
JNHEscher said:
We're back and I'll catch up this eve.
David Tillett at ITP got back to me on Friday about the torque converter ratio. Ours is a TC496 which is a 1.78 that shifts at 2100/2250 RPM.


Alright, so I managed to read through your reply during a fuel stop on Friday, @O2rexwi. I was kinda hoping you would throw your knowledge at this one. I'm quite familiar with driveline setups on most vehicles. Your'e correct about the torque converter. Just need the info on the t-cases and AT4K planetary sets, so here is goes...

The t-case preference is the T800 with a 0.80:1 high gear and 50/50 bevel gear center diff. No idea what the prices or model numbers are for that t-case option setup or if that combo is even an option to find anywhere in the market. I haven't been able to find any other pictures of the T800 t-case than what Axletech shows on their sites. One case shown has four flanges. Four flanges on the T800 might allow for one case to operate all the axles, though I don't mind having to run two t-case to do so if they only have an input and the front and rear outputs.

To manage highway wheel speed on commercial tires that have something close to 486 revs per mile, I have to know if the AT4K planetary wheel end ratios can be changed without spending months tracking down what might be a unicorn of a gearset six to eight times because the 3.55:1 set that appears to be the most common the the narrow and wide axles for sale is certainly not going to work. The only other Axletech combination remedy that I'm currently aware of would be to stack t-cases so that the overdriven high gear drops the overall ratio enough.

With 0.80:1 case and 1.58:1 diff = 2.64:1 wheel end
With 0.90:1 case and 1.58:1 diff = 2.34:1 wheel end
With 1.00:1 case and 1.58:1 diff = 2.11:1 wheel end

With 0.80:1 case and 1.92:1 diff = 2.17:1 wheel end
With 0.90:1 case and 1.92:1 diff = 1.93:1 wheel end
With 1.00:1 case and 1.92:1 diff = 1.73:1 wheel end

What I have not yet found out is if the four-pinion gear set ratio is changed with just the sun gear and planetary gears or if the sun, planets, and the ring hub have to be swapped. I've been punching in Axletech keywords on eBay for almost a year now and have only seen a few sun gears and planet plates, as far as 4K wheel end internals. If any of those above (or close to) wheel end ratios and T800 in my preferred trim are available, the t-case option is a doable. I believe I still have the number to call the Axletech guy. Problem is that he almost always has to be given a part or model number. If anyone has the list of wheel end ratios that cover those between 1.73ish and 3.55, gimme.
Edit: I may have the ratio question answered here - https://www.axletech.com/at-admin/re...etterweb-1.pdf 3.22:1 wheel end looks to be the highest.

Using the tandem axles really hasn't been of much interest. No steer option and I would like to avoid cutting up any of the axles because the narrow and wide steers already fit just right.​
There is a version of the AT4000 that has a 1.0? (sorry can't remember exact number but between 1.00 and 1.10 to 1) ring and pinion but I have been around a lot of Axletechs and have only seen 2. It has a pinion flange that looks like the round flange on a top loader 5 ton.

You could also use the 5 ton Rockwell T-1138. It has an overdriven high gear. I think it is 0.83:1.
 
jd8420 said:
There is a version of the AT4000 that has a 1.0? (sorry can't remember exact number but between 1.00 and 1.10 to 1) ring and pinion but I have been around a lot of Axletechs and have only seen 2. It has a pinion flange that looks like the round flange on a top loader 5 ton.

You could also use the 5 ton Rockwell T-1138. It has an overdriven high gear. I think it is 0.83:1.​
I must find that diff. Three or four of them, to be exact. I'll punch in the numbers right quick to check, but I'm thinking that would take care of the rest of the gearing being too low.

--Bingo. 1.00:1 R&P with a 0.80:1 t-case high range puts it at 70 MPH right in cruising RPM. Can even do the Texas 80 speed limit at 1944 RPM which opens up to being able to use the 0.90:1 high range ratio as well. That's with the 3.55:1 wheel end ratio. Swapping complete center chunks is likely easier and cheaper than swapping wheel end gears. If the R&P is 1.10:1, I'd need the 0.80:1 t-case high gear to stay in acceptable RPM range.
 
jd8420 said,
JNHEscher said:
I must find that diff. Three or four of them, to be exact. I'll punch in the numbers right quick to check, but I'm thinking that would take care of the rest of the gearing being too low.

--Bingo. 1.00:1 R&P with a 0.80:1 t-case high range puts it at 70 MPH right in cruising RPM. Can even do the Texas 80 speed limit at 1944 RPM which opens up to being able to use the 0.90:1 high range ratio as well. That's with the 3.55:1 wheel end ratio. Swapping complete center chunks is likely easier and cheaper than swapping wheel end gears. If the R&P is 1.10:1, I'd need the 0.80:1 t-case high gear to stay in acceptable RPM range.​

I am thinking it was 1.08 something or 1.09 something to 1.
 
I emailed Leo with AxleTech about getting a T800 transfer case service manual. Here's hoping. He's given me some decent documentation on the axles.

These pics are of the T600 which is a model I see all over the place on build threads. Four flanges - one input, two outputs for front and rear axles, and the forth is said to be a PTO output. That fourth flange I colored in yellow and the fork and dog clutch for it in orange. The PTO shaft looks like equivalent beef to the rest of the assembly to be suitable to drive an axle as well. The clutch assembly to engage it appears to be the same assembly that is used to engage the front axle output.

I'm pointing this out because I would most definitely rock a T800 transfer case if they have the option of that same PTO style output. Alas, the pictures on the interwebs do not show enough of the case to determine this and I cannot find a working link to a manual. The T600 cannot be used in my application because it is not stout enough (300hp/7,744tq vs. 450-600hp/18,439tq).

The PTO output option matters so much because I would set up the driveline in this way - trans to t-case input, t-case lower outputs to each rear axle (pending the ability to fit all this), PTO output to front t-case input that would split its lower outputs to two front axles if that were to happen.
Edit: Gotta think on that arrangement a bit. T-case between axles would lose the center diff because that's between the t-case outputs.


Found this a few weeks ago - https://manualzz.com/doc/8020679/t-8...cases-overview. Just read over it again. PTO on the T800 meaning is must be a four-flange t-case like the T600.

800.jpg
801.jpg
 
Curiosity kills the cat. Ran the numbers for traction motor style drive, this eve. Pictured is the TM4 Sumo HD HV3500. Puts down 2,541 ft. lbs. This is the motor that would closely match the OE drivetrain output if two motors were used to each drive a T800 t-case for each pair of axles (front and rear).

Two motors with such high torque would be used because of the constant overall ratio of 5.49:1 of the 0.8:1 t-case and 6.86:1 AT4K axle ratio as opposed to the overall ratio of 21.9:1 you get with the Allison trans and Rockwell axle multiplying the Detroit torque. Theoretical peak cruising torque is really good, too. I would need a minimum of 377 lb. ft. and the TM4 continues to deliver 725 ft. lbs. at peak RPM.

I'm still toying with this idea because I would still like to make a cost comparison between setting up the complete transfer case and driveshaft setup needed to build what I want and what motors and controllers would run to make a simpler setup that would not require so much in the way of driveshafts. Pretty sure the motors would cost more. I'm going to run the numbers on motors for direct drive to axle pinions.

Edit: I should add that the HV3500 weighs 750 pounds and the case is about 20" in diameter and 22.5" long.

More edit: Negligible difference between t-case and no t-case. T800 0.80:1 x wide AT4K 6.86:1 = 5.49:1. Narrow AT4K = 5.64:1. Same Sumo HV3500 does the job and until I hash out all the small details, I think, if I were to use beam axles, I would mount a dual-shaft motor between axle pinions and suspend the motor with some sort of Watts link setup so that it could move with the the articulation of the axles. ISAS units would just accept a hard-mounted motor between the pinions with maybe a monster rag joint of sorts. Just my thoughts for now.

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Ran the numbers for an individual motor at each axle pinion. Sumo MD HV2100-6P works great. Ends up putting quite a bit more torque to the ground than the pair of HV3500's.

A few months ago I poked around for TM4 motors for sale and a guy contacted me about one that his shop had for sale. It's the motor and controller kit that happens to have the HV2100-6P. Shop boss wanted $12k for it, so that'd be $48k to set that up if three more were found at the same price. Ouch. He said their kit was out of a 14k lb. bus project that got scrapped.

With all that in mind, I'm focusing on locating at least two T800 t-cases and getting a bunch of driveshaft sections made. Where, oh where, can I find a couple T800's?

804.jpg
 
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Mr. Mindless said,

Seems silliness to me to go down the electric road but still need tcases and driveshafts.

That cost is equally silly for 12k per motor.

Find an application and start cursing dovebid and gsa auctions for equipment that uses them?
 
Mr. Mindless said:
Seems silliness to me to go down the electric road but still need tcases and driveshafts.

That cost is equally silly for 12k per motor.

Find an application and start cursing dovebid and gsa auctions for equipment that uses them?​
Really only silly because of the cost, if you ask me. At least if one were able to mount a motor directly to an axle. Routing wires is a piece of cake. A motor on a t-case plus the driveshafts is definitely no better than just connecting the t-cases with driveshafts to an engine and transmission that's already there.

I hadn't heard of DoveBid. I'll check their stuff. Been all over the GSA's and come up dry. Can't even get a ballpark price on a T800. Lot's of those Fabco t-cases for sale, but they're priced high, have a 1:1 high range and no center diff.

Gearing that works - Current HT740D trans, 0.8:1 Axletech T800, 1ish:1 Axletech center chunks with 3.55:1 wheel ends. Finding the T800's and high ratio center chunks might take a while. I'll peruse other axle manufacturer options, although Axletech would make me a happy camper.
 
If I'm right on the T800 specs, I'd be looking for a AT2523DTALN. Nothing comes up with a search for that or any variant that changes a few of the options. Leo with AxleTech is out of the office until January 2nd. Curious to see what he says about where to find a T800. Starting to think I'll have to settle for some T600's. They do fine in mud trucks.

808.png
 
Stealing pictures again. Did some more eBay browsing and found a couple big sellers had a bunch of AxleTech planetary parts listed again. The guy in Fort Smith, AR. has had the NOS carrier plates listed for quite a while. Without parts on hand, I wasn't entirely sure if the sun a planet gears variant tooth profiles were designed to fit a single ring gear. Knowing planetary gears, you know that's not really an option - but I thought about that anyway.

Found a 69-tooth ring gear(for the 3.55 ratio) and the complete ring-on-hub assembly(pictured). Checked my picture stash and the manual. Something I didn't really pay attention to before is that the ring gear splines onto the inner hub(bull gear?) and appears to be held with a couple snap rings. The wheel end manuals continually show the ring gear and hub as one piece. My conclusion is that the ring gear and inner hub have to be a matching spline, so changing one wheel end requires the hub, ring, planets and sun, which, according to eBay prices, costs more than buying a complete axle.

I haven't gotten any return phone call from Jay in Oklahoma. After our convos, jd8420, I dug around and found him on the book of faces. That appears to be the most recent place he has made any communication that I can see. Sent him a message about the high-ratio AT4K diffs. Getting those is about the only practical way I can make the AxleTechs work for the highway. I went through the other available axles the other night and nothing works out as well as AxleTech.

809.jpg
810.jpg
 
Brought 4Runner in for the maintenance. I pass by a lot full of decommissioned city and coach buses owned by a coach bus company owner in Colorado Springs. There is now an 8x8 HEMTT parked with the buses...

Leo got back to me this morning about the T800. No manual for it, but he's waiting on a reply about the manual from their French facility because that's where the T800 was manufactured.

Edit: Variety of t-case manuals - https://www.globaltransfercasesupply...r-case-manuals
 
jd8420 said,
JNHEscher said:
Stealing pictures again. Did some more eBay browsing and found a couple big sellers had a bunch of AxleTech planetary parts listed again. The guy in Fort Smith, AR. has had the NOS carrier plates listed for quite a while. Without parts on hand, I wasn't entirely sure if the sun a planet gears variant tooth profiles were designed to fit a single ring gear. Knowing planetary gears, you know that's not really an option - but I thought about that anyway.

Found a 69-tooth ring gear(for the 3.55 ratio) and the complete ring-on-hub assembly(pictured). Checked my picture stash and the manual. Something I didn't really pay attention to before is that the ring gear splines onto the inner hub(bull gear?) and appears to be held with a couple snap rings. The wheel end manuals continually show the ring gear and hub as one piece. My conclusion is that the ring gear and inner hub have to be a matching spline, so changing one wheel end requires the hub, ring, planets and sun, which, according to eBay prices, costs more than buying a complete axle.

I haven't gotten any return phone call from Jay in Oklahoma. After our convos, jd8420, I dug around and found him on the book of faces. That appears to be the most recent place he has made any communication that I can see. Sent him a message about the high-ratio AT4K diffs. Getting those is about the only practical way I can make the AxleTechs work for the highway. I went through the other available axles the other night and nothing works out as well as AxleTech.

Started cutting a pathway for some 2x5 tubing to weld on top of the 3x3. This will be the rest of the wall between the battery bank and engine bay, or basically the wall between the drive and tag wheel tubs. Gonna get it cut to 97" long and notch the center so that it makes a complete run all the way across with an arch over the conduits in the center chase. I might have to bend it a bit at the arch. There's 5" between the top of the 3x3 and floor lip at the walls and 5-1/2" between the top of the tube and top of the floor frame at the center. Word to anyone else ever rebuilding this much of your MCI: Not a damn thing is straight in these buses.​
Jay is member on here but hasn't been on here since March. jayz8886 is his screen name.
 
jd8420 said:
Jay is member on here but hasn't been on here since March. jayz8886 is his screen name.​
Night owl too, eh? Haven't heard back from him on FB yet. Being holiday time, I don't figure I'll hear much from anyone until a few days into January. I'm going to try to get some time next week to stop by and get info on that HEMTT.


Edit: Going through the AT4500 manuals and brochures. Final drive ratios of 3.9 to 28.0. With a 3.55 planetary ratio and 3.9 final ratio, that leaves a R&P ratio of 1.098:1, so somewhere out there, like you said, jd8420, there is indeed a 1.10:1 AT4K diff. That'd be one large pinion gear.
 
arse_sidewards said,
JNHEscher said:
Edit: Going through the AT4500 manuals and brochures. Final drive ratios of 3.9 to 28.0. With a 3.55 planetary ratio and 3.9 final ratio, that leaves a R&P ratio of 1.098:1, so somewhere out there, like you said, jd8420, there is indeed a 1.10:1 AT4K diff. That'd be one large pinion gear.​
Just because axletech made a couple 1:1ish ratio 3rds doesn't mean that they made more than a literal dozen for prototypes for a vehicle that someone wanted to build a few of to convince someone else to buy. If nobody ordered them en-masse then there won't be any floating around the used parts market. Just because it's in the manual doesn't mean you can actually find one for sale.
 
jd8420 said,

I have actually seen 2 of them. They are rare and I have no idea what they came in but they are at least some out there unless I saw the only 2 on the planet.
 
arse_sidewards said:
Just because axletech made a couple 1:1ish ratio 3rds doesn't mean that they made more than a literal dozen for prototypes for a vehicle that someone wanted to build a few of to convince someone else to buy. If nobody ordered them en-masse then there won't be any floating around the used parts market. Just because it's in the manual doesn't mean you can actually find one for sale.​

I know. The fact that this has been taking me so long to compile the correct parts with certain manufacturers and models tells me so. For the most part, I've been maintaining the effort to stick with parts that are common and still peppered all over the states, including replacement parts. I'm wide open to researching any other axles and t-cases that meet the criteria. AxleTech is still under my spotlight. Just have to nail down part numbers and availability before I give it the go ahead.
jd8420 said:
I have actually seen 2 of them. They are rare and I have no idea what they came in but they are at least some out there unless I saw the only 2 on the planet.​

I'm going with the assumption that they're rare. Same with the T800. Fingers crossed, but picking through other options at the same time.
 
jd8420 said,

A Marmon-Herrington MVG1600 has a 0.89:1 high range and has a 30%/70% split and is heavy duty enough. There was a guy on ebay a while back that had 2 for $9500 each or best offer. There is a couple on there now but they are over $40,000. I have the add saved on ebay if you want to send him a message and see if he still has one. He ran the add for a long time. I bet he just didn't renew the add.
 
jd8420 said:
A Marmon-Herrington MVG1600 has a 0.89:1 high range and has a 30%/70% split and is heavy duty enough. There was a guy on ebay a while back that had 2 for $9500 each or best offer. There is a couple on there now but they are over $40,000. I have the add saved on ebay if you want to send him a message and see if he still has one. He ran the add for a long time. I bet he just didn't renew the add.​
I was searching Marmon-Herrington and Oshkosh t-cases last night. There's some Oshkosh 55000 cases for $2,000. Probably not going to spend much more than that on each t-case. T-case alone costing as much as the TM4 motor and controller package won't make the t-case and driveshaft setup worth the cost or fabrication effort.

I've been searching for Oshkosh TAK-4's again since the last two NOS units sold on GovPlanet for less than $1k each and they mate right up with the Oshkosh 55000. Still don't know their differential or planetary ratios. If the diff ratio is close enough to 3.3:1, I can lock the planetaries and have the correct ratio to match the Allison. Gotta go check out that HEMTT in Springs. The owner of the buses is super cool and we were going to walk the yard last spring so I could check out all the buses. Bet he'd let me crawl all over the HEMTT and take measurements. Major plus if it has the TAK-4's because independent suspension drive axles would be heaps easier to set up on a coach bus due to the powertrain position. AT4500's would likely fit just right, whereas TAK-4's and AT5000ISAS's might be kinda large (and too heavy until I strip them down). Doubt we could afford a complete HEMTT for parts, but you never know.
 
arse_sidewards said,

It's a real shame you need to drive three axles directly off the T-case since there's boatloads of FWD and Oshkosh plow trucks being parted out on CL that have otherwise suitable transfer cases.
 
arse_sidewards said:
It's a real shame you need to drive three axles directly off the T-case since there's boatloads of FWD and Oshkosh plow trucks being parted out on CL that have otherwise suitable transfer cases.​
? Got a link? There's been nothing but some junky Rockwell stuff around me.

So what I'm hoping to achieve is three drive axle with enough center differentials to allow each axle to be free of gear bind. Overkill, I know, but I'm digging into this possible setup so that there's no tire scrub from turning with any two axles engaged. This would require three transfer cases, so I'm thinking about just driving the original drive axle position and the front axle, then swapping in a caster steer tag so that I can do the above with just one t-case. Kinda depends on what lands in my possession since it's not so easy to find a person selling individual AxleTechs. Richard in Arkansas did say that he will sell them any way just before our call got cut off again. Didn't catch a price, though.
 
jd8420 said,

The Oshkosh 55000 is a monster. If you are going that big, you might as well just look for a M1070A1. You get the Axletech 5000 axles and the Oshkosh 30000 transfer case powered a C18 Cat and Allison 4800. Drive that monster around a while and you would drop the electrical conversion idea after getting used to that kind of power.
 
jd8420 said:
The Oshkosh 55000 is a monster. If you are going that big, you might as well just look for a M1070A1. You get the Axletech 5000 axles and the Oshkosh 30000 transfer case powered a C18 Cat and Allison 4800. Drive that monster around a while and you would drop the electrical conversion idea after getting used to that kind of power.​
Damn. Yeah, that's a bit large. I was thinking the 55000 came in the Oshkosh HEMTT M9xx's lol. The service breakdown on it isn't real great, but doesn't look like it sports a center diff.

I think I might sketch up the two driveline scenarios I'm thinking of for a visual reference. Maybe even throw in the quad axle setup for the fun of it.
 
jd8420 said,

Yes they are in the M977 M984A4 and similar trucks but that is a big truck. It is about 5 inches longer and 10 inches taller than a 5 ton transfer case.
 
jd8420 said:
There is a center pass through type differential for the Axletechs that you could use with a steering independent outers. Like this one:

https://www.ebay.com/itm/Axletech-G-...MAAOSwvjtcaZgA​
I've been watching that one for a quite a while now. Didn't know what vehicles it was designed for and it doesn't really look strong enough. I know nothing else of it, though. It looked to me like the shafts hanging on it drove some wheel hubs in some sort of wishbone suspension and that the other flanges were for the drive shaft. Googled the part number last last month and didn't come up with much other than an Amazon listing for the same thing - https://www.amazon.ca/General-Dynami.../dp/B076VXW8JY

Edit: I'm going to message that guy(Wartime Finds) in Bells. I remember you warning me against the used AxleTechs that he had on eBay because the kingpins might be bent. He seems to have crap load of new and used AxleTech stuff and probably knows plenty about it. Stumbled onto his FB page last week as well. I've been punching every keyword I can think of into every online platform that I can come up with.
 
jd8420 said,

I am not sure what they came in either. It is hard to get an idea of size from the pictures. The flanges for the drive axles looks like some of the earlier designed independent front ends.

I may have said it wrong I can't remember but I think at the time he had some used narrow steer axles that he had listed on ebay. A lot of times the narrow ones are taken out and sold as scrap and I was trying to tell you to make sure the kingpins were not egged out from running over a land mine which is why they were usually removed. I have his phone number if you want it.
 
jd8420 said:
I am not sure what they came in either. It is hard to get an idea of size from the pictures. The flanges for the drive axles looks like some of the earlier designed independent front ends.

I may have said it wrong I can't remember but I think at the time he had some used narrow steer axles that he had listed on ebay. A lot of times the narrow ones are taken out and sold as scrap and I was trying to tell you to make sure the kingpins were not egged out from running over a land mine which is why they were usually removed. I have his phone number if you want it.​


I'm going with 18" long, 14" wide and 14"-16" tall according to the Amazon pictures. Flanges look kinda like KV150. I'm not entirely sure how the whole thing operates.

Think that's pretty much what you told me before so I've been staying away from the narrow take-outs. Wouldn't mind his number. I'll use whatever communication method it takes to get answers lol.
 
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