Need advice on a custom project

[04mustang]

I've thought about putting the mt654cr from the m939 trucks behind it, but it's rated to 300hp, so would the 330ho from the c7 be too much engine or is 300hp rating a conservative number?

It seems like you are an engineer or at least extremely familiar with engineering to be able to use solid works and programs as such.
I would say that anything built within the last few decades has been engineered to have a safety factor in it. The rated amount of whatever is being rated is actually quite a bit less than what it can handle due to an engineered safety factor. If I'm remembering correctly it should be around 20%. So add 20% of the 300hp rating and that will be what it can really handle. But by doing this you loose the wiggle room for overloading.

Corey

 

[Sikorsky502]

I'm a lead engineer for Sikorsky. I started life as a crew chief on the Blackhawks with the 101st airborne division and deployed to Iraq in 2005-2006. I worked my ass off and got myself to where in at today. I turn 32 next week so I'm pretty proud of myself. Waiting to see if the regulatory stuff comes through for Lockheed martins acquisition of Sikorsky. If it does I'm going to try and get into the Orion program, which is the manned mission to Mars program. Not a bad journey for a guy who dropped out of high school at 17 and got a GED to join the army. Original weight of an m3 Halftrack is 8.4 tons. And with the original motor having about 147hp that equals about 18hp per ton. Now if I go with the 3116 cat at 290hp and I'll add probably 2 tons minimum to the weight I'm looking at about 29hp per ton. Not bad. I can probably tweek the fuel on the 3116 and get a few more ponies.

 

[kubotaman]

Thank you for your service sir.

 

[Sikorsky502]

Thank you. It was my pleasure to serve my country. Made me the man I am today. Picture of the door only is a frag 5 and the doors on the Hmmwv are frag 3.

 

[Sikorsky502]

The difference is, frag 5 is thicker and glass on the outside and frag 3 glass is on the inside.

 

[bikeman]

I'd go with the Frag 5, they are most similar to what the MRAPs would have, esp these days (vs. the first versions)

 

[Sikorsky502]

The frag 5 doors I've found are complete except one is missing the window assembly. Could get it made from the dimensions from the other door, but not sure where to go for the glass. I do like the heavier doors with more room from the windows being outside rather than inside.

 

[wgtactical]

The frag 5 doors I've found are complete except one is missing the window assembly. Could get it made from the dimensions from the other door, but not sure where to go for the glass. I do like the heavier doors with more room from the windows being outside rather than inside.

http://usarmorllc.com/

 

[Sikorsky502]

Ok so here's a question for someone with more experience than me. The original ratio set up on the Halftrack was 6.8 for the front axle and 4.44 for the rear. I want to run a modern axle on this vehicle and I'm leaning towards the deuce front axle. Firstly, do you guys think that's a stout enough axle to handle the weight of the armor and combat load and secondly, the deuce axle has a ratio of 6.72. I've been read that if the front and rear axles have a difference of 1% that's ok. Is that true? The original halftracks ran a 39" tall tire, I'd like to run modern 40" tall michelins. any advice on axle and tire options?

 

[tobyS]

Ok so here's a question for someone with more experience than me. The original ratio set up on the Halftrack was 6.8 for the front axle and 4.44 for the rear. I want to run a modern axle on this vehicle and I'm leaning towards the deuce front axle. Firstly, do you guys think that's a stout enough axle to handle the weight of the armor and combat load and secondly, the deuce axle has a ratio of 6.72. I've been read that if the front and rear axles have a difference of 1% that's ok. Is that true? The original halftracks ran a 39" tall tire, I'd like to run modern 40" tall michelins. any advice on axle and tire options?

Have you done the math for revolutions of the drive-shaft per mile on the rear?

How about the (929 series) 5 ton's 8.3T, Allison and air shift transfer case...and the frame.

Not exactly what you are building but check out this;
https://www.youtube.com/watch?v=9-9uzLBtMtY

 

[wgtactical]

Not exactly sure what void the ripsaw is expected to fill or role that it is needed to play but I like it for the novelty value. Tracked vehicles obviously have their place but the track itself is always going to be the weak link. As far as the deuce axles goes, they are the ones found in the Cadillac Gage V100. The only notable change from going to the truck to the armor are the lockers and slightly larger diameter axle shafts. The wheel hub spindles and bearings are the same so the load bearing capability wasn't a concern as much as the added torque that came from the increased traction that the added weight was responsible for.

 

[tobyS]

"Not exactly sure what void the ripsaw is expected to fill or role that it is needed to play"

I posted it as an example of a higher speed tracked vehicle. I find the suspension interesting as opposed to a more rigid one.

Have I missed it, or is there enough information about the track and rear gearing, besides the former ratios, that gives enough information to calculate the relationship of drive-shaft turns to feet moved? Obviously the diameter of the rear drive sprocket(s) and the thickness of the tracks will have a big impact in addition to the ratio of the gears. Without knowing exactly what is being used on the back, how can one determine the front?

 

[wgtactical]

Obviously the diameter of the rear drive sprocket(s) and the thickness of the tracks will have a big impact in addition to the ratio of the gears.

Pitch diameter of the drive sprocket is all that's needed. The thickness of the track wouldn't have any affect of the distance per revolution unless the track never left the sprocket (as in being completely wrapped around it much like a tire on a rim)

 

[Sikorsky502]

The rear drive axle on the Halftrack is 4.44. This is because the rear sprocket diameter is smaller than the front wheel, which is an NDT 9.00x20 making the front tire 39 or 40 inches in diameter. Some places I've looked call it 39" and some 40". Anybody have the real diameter? The question is really about the relational changes in ratio when I put on an axle with a 6.72 ratio and then change the front tire diameter to adjust the ratio back into the correct revolutions for the front tire and rear sprocket. I've baselined the axle to be a 2.5 ton rockwell because the width seems to be close to the original halftracks width. I've found that some of the planetary axles from an MRAP have a ratio of 6.852 and that would work, but they're a little wider than the rockwell. Anybody know the width of the Halftrack front axle specifically?

 

[tobyS]

Pitch diameter of the drive sprocket is all that's needed. The thickness of the track wouldn't have any affect of the distance per revolution unless the track never left the sprocket (as in being completely wrapped around it much like a tire on a rim)

Yes, I see you're right with the PD, since that is the part that determines length of a chain. So with a PD and ratio, one can get drive-shaft rev/mile. Then one can change the front tires or axle ratio to match the rear. Other than the TC with sprag clutch, they are equal front to back.

 

[tobyS]

The rear drive axle on the Halftrack is 4.44. This is because the rear sprocket diameter is smaller than the front wheel, which is an NDT 9.00x20 making the front tire 39 or 40 inches in diameter. Some places I've looked call it 39" and some 40". Anybody have the real diameter?

I would use the rev/mile stats for the particular tire, not only dia..

Do you already have the rear end or the sprocket to know you're fixed on certain numbers to match it too? What are you thinking for the rear drive besides the ratio math (since you know what they did in ww2)? Does it meet the performance goals you stated?

 

[Sikorsky502]

using the same rear axle and sprocket combination as the original is one of those things I can't see away to change. The track is of the continuous band type and the only way to change the sprocket diameter would be to move the rear axle forward or aft to compensate for its size change while maintaining the appropriate about of track slack. The rear axle meets my needs as far as performance. The setup has been used for decades after WW2 with various advancements to power increases via stronger Diesel engines. This issue of ratio is a sticking point because I want to be able to use the front axle in a 4x4 setup, but if the ratio is off then it'll jump around and be useless. This isn't a problem most builds encounter because most vehicles are all wheels or all tracks and the ratio isn't different between axles. I'd really like to use the Axletech 4000 Mrap axles, and the ratio is good, it's just that it's like 94" from wheel face to wheel face. I think the rockwells are only 78" or something. Any ideas?

 

[tobyS]

So have you contacted a track manufacturer to have a spec on a track that can do 50? The Track sounds rather special and from what I can see, even the ripsaw would be challenged at that high speed, and it's got gobs of travel in it's dampened (coil over shocks) torque arm suspension and the track seems designed for high speed.

What is the Israelis track manufactures specs and are they a supplier for the entire suspension/drive unit, or only the track? Provide a link please. There are a lot of rubber track manufacturers coming out with new designs, mainly agriculture. Have you contacted any for their info?

And no, you are not limited to the same sizes or ratios as a prior HT. You need an equal number of revolutions per mile on the back and the front and it doesn't matter how you get it. Like say you have a 4.10 gear for the rear on hand/available. That's close and worth going through the math to see if say an 19 tooth sprocket would be better than an 18 (thus a known PD if you know the size link) and then whats needed for front can be fine tuned to your 1%. I can't answer the width question, I only have 5 tons.

I've considered something similar for forwarding logs, but by putting a track around either super singles or duals. One place a couple towns from me makes an all metal track for skid steer loaders, going around tires.

Good thing you're young.... building one by buying the individual components from military suppliers may bankrupt you more than once. It has our government.

 

[Sikorsky502]

So wanted to give an update on my build. I moved a few months ago back home to Alabama, so things went on hold for a bit with the bulk of the build and I just bought and sourced parts. I got a turret from an M1114/MRAP for the Halftrack. And also put together a full VIC-3 system as well. I'm also waiting to hear back about a set of HMMWV knockout armored Windows for it also. I've also found a master mechanic near me now to build the custom frame too. Tracks are now available new, so I've also located a full setup for the rear Halftrack portion. This has gotten me thinking and researching what front axle I'm going to go with again. It seems I've gotten my Halftrack models mixed up for my previous plans and now I'm stuck trying to figure out how to get the different axle ratios to line up. I'm in need of someone with knowledge in this area. Issue is this, the front axle of the white model Halftracks is 6.8:1, but it ran a 8.25-20 tire which is like 37" in diameter and an equivalent diameter tire that'll fit an MRAP rim to them fit the MRAP axle is not available, to my knowledge. The rear axle for that model is 4.44:1. The International model Halftrack used a different front axle ratio, but I'm having trouble finding what it is, used a 9.00-20 tire; which is like 40" in diameter and there's plenty of usable new tires in that size like the Michelin XZL's. The International Halftrack used a rear axle ratio of 4.22:1. So what do I do? Can I put larger tires on a different axle with a lower ratio to bring it in? How does tire size affect the ratio if at all? I'm just plain stuck and need some expert advice. Thanks, James.

 

[kubotaman]

How the heck did you get an up armored turret from a M1114? I did not think those had a snowballs chance in h*ll of getting out. Any pics?