Need advice on a custom project

[Sikorsky502]

I'm posting this here, since I'm not interested in a lesson on what I should or shouldn't spend my money on or why I need to do what I want. Typical of the purists over on G503 it's always a question of "why" and "you should restore it for future generations". I get it, this build isn't what they would do, but I'm not Interested in talking the finer points of a GPW or the correct windshield nut for a DUKW. I'm simply looking for people's advice on things they already know. Such as dimensions, weight, availability of parts, etc. thanks for any help you guys can give.

Ok, so I've been wanting to do a custom Halftrack project for a while and I'm at the point where I need you guys advice before I start buying big items. The idea I want to do is a modern Halftrack MRAP. I'm thinking I'll do it on a nice solid m3 frame since its a double frame and I need it to be stout. I'd like to use an MRAP front axle and a CTIS system on the front tires. I'm thinking either a cummins or cat engine from a military truck and same for tranny and transfer case. I want to enclose the rear and cab at the same lines and height as the canvas cover for the original. I'd like to use ballistic aluminum like used on the m113 or bradley to help keep weight down while still keeping it ballistic. Front doors Id like to use the armored Hmmwv doors and the front glass and windshield would be from the hmmwv as well. Gunners station would be the motorized turret from the hmmwv too. I'm still not sure about how to do the hood but I'm leaning towards a grille from the up armored Lmtv I found for the front end. So obviously this is a big project, but one I really want to do. Need everyone's thoughts on this and any problems anyone sees.

ive established the Halftrack frame might be a weak point and someone suggested doing a custom frame. Any ideas where I could search for this type of thing.

 

[dmetalmiki]

Looks like a huge project you decided to invest time effort and money into. So ok there is absolutely nothing wrong at all in "going your own way" with it. Purists etc do not need to have a look in (let alone a say) So do what it looks like your planning to do. The way you want to do it. As you progress you will find it works out to your (own) satisfaction..(or not). I for one will be following this project with great interest. So, the usual pictures and reports as you proceed please.

 

[Sikorsky502]

There will be plenty of pictures on this one and a lot of questions I'm sure. I'm looking forward to bringing the spirit of the Halftrack into modern warfare and hopefully have something that even the purists want to checkout at the rallies.

 

[zout]

I know one thing - those giving advise of what to do and what to spend your money on and what you want - tell them advisers YOUR taking DONATIONS in cash and you will only consider doing it that way - BUT their donation is non returnable and in no way their name becomes part of the title. See how many takers you have.

I am not attorney nor know anything productive except there are lots of folks wanting to help you spend your money - while their stuff looks like trash OR its so perfect you cannot touch it - go near it - sit in it nor take pictures of it.
Folks I know wanna drive it and have folks sit in it to talk about history - its not perfect nor RESTORATION better than the military had it built - it was not meant to last that long. They were building tools to get shot at - move stuff - get blown up and not looking for a CUSTOM Militay vehicle for looks - it was only a tool that was built well with our tax dollars to the lowest bidder.

Do it the way you want it - plain and simple and stop askin folks what they think - cause their asking other folks what they think to do to their stuff.

 

[NDT]

Lots of challenges to overcome. The engine compartment just fits a 386 CI six. The rear suspension rests on 4 puny volute spring packs. Will the available front axle ratios match the ratio of the rear drive?

 

[Sikorsky502]

I've taken into consideration the different axle ratios on the Halftrack. Stock front axle is a 6.8:1 ratio so I know I need to keep to that or within 1% to be able to use the front axle. What I've found is the m35a3 axle has a 6.72:1 ratio and if I put 12.5x20 tires on it at 40" tall that'll take me to with in the 1% difference from the original ratio. The m35 axle also has the lines for CTIS which I plan to keep on the front tires. The Israelis put Detroit 6v53 engines in there's so I know I can at least keep the same frame distance and put in an engine of comparable dimensions. I'm leaning towards the CAT c7 that's in the FMTV with the same Allison transmission. That'll give me modern power and pushbutton gear selection found in the current issue MRAPs. Also I've considered the volute springs being something I should address and I've considered finding the volute spring diameter and replacing with same dimension coil springs with shocks inside them to further promote a better ride and off road capability. MRAP front lead springs and shocks will be used in the front axle. MRAP troop seats in the back and cobra seats up front for the driver and commander. I'm going to use an MRAP front bumper, possibly the one from the RG-31 for the front and add a warn 18k winch front and back. I just bought some rg-31 spare tire hoists so I'll put spare tires behind the driver position with the hoist above. Similar to the rg-31. There's new Halftrack track being produced now so getting tracks not an issue. I'd like to do a rear ramp on the back like the maxxpro or m113. And eventually eyecon 360 lighting all the way around and a Flir ball up top for night ops.

 

[marchplumber]

Wow! Put some thought into it. Will be watching and see how it comes along. Sounds like she might be fully operational .

 

[B3.3T]

I would be concerned with the added torque you are planning to add to the track. Even the new track being produced is only designed for the original performance specs. The added weight and added torque could end up far exceeding the new track and stronger variant do not exist. Since you are starting from scratch, I would look seriously at commercially available track/boge systems designed with your specs in mind. It will be much more cost effective in the long run.

 

[Sikorsky502]

I've thought about how the added power would affect the track and even the rear axle. I've submitted the question to the new track manufacturer in hopes of getting an answer on what the limits of the track will be. The Israelis put higher torque and horse power Diesel engines in theirs and ran at speeds in excess of 60 mph. That seems like it would do pretty well. Any ideas on other rear track and suspension?

 

[bikeman]

Ok... so... you want an MRAP halftrack... why not start with an MRAP Chassis? There's one being advertised on here right now. I'd go with some sort of Caterpillar track system. find a smaller or medium sized Dozer and pull parts off of that. That way you don't run into supply issues later on. If you aim for a Caimen style MRAP, I think it could be done pretty easily... use a Freightliner/M915 style hood or something...

Now, keeping with the M3 halftrack... Still go with some sort of Caterpillar or Bobcat track system, bogies and such. Or John Deer, or other commercial producer. There are tracks that would have to fit your dimensions/goals. You're modernizing anyways, so why stick with the old system?

 

[Sikorsky502]

The problem with using a frame off of something like a caiman is that I would still need to add the bend in the frame where the rear axle for the sprocket mounts. Using track and suspension off of an excavator would be tough since those really only go a few miles an hour. At least the ww2 halftracks can do at the very least 45 mph no problem. The only real parts off of the Halftrack would be the axle, idler assembly, bogie assembly and bogie arm off the frame. I've found a company that can do a custom frame as beefy as I need. It'll be double c-channel the whole length. And all the mounting points will be welded on at the correct points for engine, axle, etc.

 

[bikeman]

That works, I don't have a lot of knowledge of the halftracks.

 

[Wayofftrack]

ive established the Halftrack frame might be a weak point and someone suggested doing a custom frame. Any ideas where I could search for this type of thing.

Sorry for the negative waves on the G503. I'm clintm20 over there. I know that one guy was trashing halftrack frames pretty hard but I have a lot of experience with them and as long as
you get one that has not been abused I think you would be fine. I would definitely go with a longframe (m3) style frame with the double c channel if you decide to use a original frame. They were built to take the heavy guns like the 105 and 75 and as I mentioned on the 503 and you note here the Israelis had no trouble with the diesels breaking tracks that I know of. We are at the point now where a lot of completely worn out, overworked and overloaded halftrack junk is being passed off as restorable so there are a lot of bad frames floating around out there, especially M2's. Imagine the weight of a halftrack retrofitted with a 50's or 60's era cable crane. Its over stressed before it even pics up it's first load.



I think this is the Argentine halftrack made from US components someone mentioned on the 503.

 

[Sikorsky502]

I would love to do a Halftrack like the Argentinian one, but I think that's way out of my fab skills and budget. Off the shelf stuff is reasonably priced and I can make it work. I'm going to try and put together a pictorial photoshop of what I'm looking to do soon. Then it's going to be a lot of designing in solid works and try and fail and try again work.

 

[Sikorsky502]

can anyone let me know if they find any frag 5 hmmwv front doors or electric hmmwv turret stuff? Figure these will be some of the harder to come by items for this build. Thanks

 

[Sikorsky502]

I found frag 3 and frag 5 doors. Does anyone have an opinion on which may be better suited for the Mrap?

 

[kubotaman]

There was a electric HMMWV turret on g503. Not sure if he still has it.

 

[bikeman]

can you post some pics of your 3 vs 5? I'm not getting reliable on google and honestly, I don't remember ( or know if I ever did) know the difference

 

[Sikorsky502]

I'll post pictures this weekend. Ok, so I'm trying to figure out the best engine, tranny and transfer case combo. I'm looking at the 290hp cat 3116 and the 330hp cat c7. I don't want full time 4x4 so I don't want to use the transmission used on the Lmtv/FMTV because it's not a divorced transfer case and I'm pretty sure that equals full time 4x4. 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? Also the mt654 is a 5 speed to overdrive. Is there any need for the OD? Is the transfer case from the m939 trucks any good or can I use one of the Arvin meritor transfer cases from the mraps? I'm not saying that I'm going to rip this vehicle down the interstate at 70 mph, but the intent of the vehicle is to be a modern armored Mrap so Id like the ability to scoot out at speed if needed. There's engines on GL now, so if I can nail this down I can bid accordingly. Thanks guys.

 

[Sikorsky502]

Whoops. I meant 5 speed NO overdrive.