Axletech isas 4500 steering set up

[Hawssie]

I came across a few new Axletech ISAS 4500 independent coil spring suspension systems. These are used in the newest RG31 MK5 EHM MRAPS. They weren't cheap but they should offer a unique offroad experience. I haven't got my hands on them yet but I am thinking of using a bobbed M931A2 as a starting point for these while adding a overdrive Allison maybe 3000 series. It would be cheaper, but more work then using a M1078, my other idea. My first problem seems to be how to set up the steering for the front axle. The rear is designed to just be pinned straight. I would assume the front steering needs to be similar to a light duty vehicle with IFS (GM or Hummer?) including right and left wheel end drag links, a center section and a idler arm and steering gear. The steering gear arm would also seem to need to have the arm parallel to the frame, also like a typical light duty automotive system. All of this is much different then a straight axle steering. I cant seem to find any pictures or starting points for creating such a system. Does anyone have any ideas for parts to adapt or pictures or documentation of a military vehicle using IFS similar to this? Maybe even a TAK 4 system, although I think this competing brand's steering is designed quite differently.

 

[73m819]

That does not look that hard to fab up, a pair would give you 4 wheel steer, this would be a fun build, I agree that a 939 series would be a better base to work with then a LMTV

 

[steve6x6x6]

There are other setup's that have all ready been released by GL. This is a pic of one setup. I have some here in the shop, but not complete.

 

[Hawssie]

Yeah I had been trying a while to collect parts for that set up too, prior to this purchase. I believe thats a TAK 4 type. But there is so many different auctions and parts kits etc. when you get individual parts. I am sure they will at some time release the whole package like in your picture or like the way I got mine. I haven't got any of the center sections like you yet though. Actually looking at that picture I am not sure some of my parts are even for that model. I think to make it more confusing there are a few different types used by the military as for different weight ratings. My parts use a double wishbone style upper A arm and drum brakes. The shape of the axle flanges of yours, to me, look like a Hummer style. But the rear ring gear shot looks more like the medium duty size. You have 2 different types?

 

[steve6x6x6]

Yeah I had been trying a while to collect parts for that set up too, prior to this purchase. I believe thats a TAK 4 type. But there is so many different auctions and parts kits etc. when you get individual parts. I am sure they will at some time release the whole package like in your picture or like the way I got mine. I haven't got any of the center sections like you yet though. Actually looking at that picture I am not sure some of my parts are even for that model. I think to make it more confusing there are a few different types used by the military as for different weight ratings. My parts use a double wishbone style upper A arm and drum brakes. The shape of the axle flanges of yours, to me, look like a Hummer style. But the rear ring gear shot looks more like the medium duty size. You have 2 different types?

This is the only ones i have right now. I seen complete setup's like this on GL auctions sell earler this year. In the pic i posted this setup has the hubs and parts as the LMTV and FMTV but these are air disc brake and not drum.

 

[Hawssie]

But in your pictures it looks like there are 2 different center sections. Maybe Its just the pictures but the picture with the 2 units have a hexagon like shape (hummer) mounting flange for the axle shafts. But the picture with the yellow pattern grease looks like that unit has round and surface serrated output flanges more typical of medium duty sizes.

 

[steve6x6x6]

OK, the one i have ( aluminum center section, weights 190 lbs. ) is a HMIS 30 series. Offered in air disc brake and hyd. disc brake. Same hub as the LMTV but all aluminum. Up to 14,000 GVW per axle. Look it up axletech website

 

[Hawssie]

Thanks, so it is even more confusing. I didn't realize that there appears to be another company making IFS for the Military. Yours are made by ArvinMeritor. So theres AxleTech, Arvin Meritor and Oshkosh's TEK4. And of course parts for all and them and their various models and brake styles all floating around GLS. One piece at a time might have worked for Johnny Cash..but it may take a while piecing together an IFS from GLS parts.

 

[Hawssie]

Back to my steering question: In the picture I posted of the RG31 MRAP is from the front of a BAE brochure in PDF. If you start with this larger picture and magnify it you can sort of make out the steering in the front. It looks like it has a pitman arm and the idler arm (or possibly dual steering gears with a pitman arms) which is expected, But both these seem to be formed with dual arms on them, one lower and one higher up. The lower ones both connect to the drag links going to each wheel and the above ones are connected together by a straight drag link, thus tying the system all together. That makes perfect mechanical sense but I have never seen a pitman or idler arm with dual arms for 2 tie rod connections on them. Anyone else seen such a system?

 

[Motiracer38]

There exists bare BAE Caiman chassis' for sale right now that include lots of good pictures of the setup. I had the opportunity to pick up a Merritor IRS assembly and was looking into what it would take to put it under the front of my truck. The steering box would have to get moved and idlers built. The biggest hurdle I had was swapping the 3rd member around to drive the correct way so I passed on it.

edit: Not as good as I remember, but the large photos tab has a pic at the bottom that may help.
http://www.midwaycarlot.com/customdetail.aspx?dealer=1153&id=14834

 

[Hawssie]

Thats a heck of a deal for what it would cost to duplicate that set up. Also Ca. emission compliant, thats a big deal for us behind the lines. But to me half the fun is building it (not that that set up wouldn't leave enough to be interesting!) That IFS system is different from mine. It looks like they use tow steering boxes, one being a slave box. That solves, and thus takes the place of using an idler arm.