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Converting M37 to D60 and 14ff axles

Posted: Sat May 14, 2011 7:53 pm
by Lebowski
Well I have an extra set of 1 ton axles. A GM Dana 60 front and GM 14boltFF with Detroit locker and disc brakes. I also have a spare GM Dana 60 frt bare front axle housing, which I coud narrow.
I was thinking of installing front springs in the manner Master Yota chronicled here: http://www.g741.org/PHPBB/viewtopic.php?t=2420. I think I will try and run Hummer H1 rims on these axles for the military look. I was trying to decide should I duplicate the M37 track width of 62", by narrowing the long side of the frt Dana 60, and using a cab and chassis dually 14boltFF (which has a 63" track width).
Or......
Should I go with full width axles, which will be about 5" wider (ie. 2 1/2" wider per side) than the stock M37 track width, and then extend the fenders for wider coverage?

I plan on using a similar steering setup, but with a forward facing pitman arm. Likely a Toyota FJ80 ps box, as it would sit nicely, and would use similar space considerations as Master Yota's Ford ps box.

The vehicle will most likely be V8/auto repowered to a non divorced transfer case. Tires in the 38-40" range (some type of TSL Swampers for 16.5" H1 rims). I will try and keep the truck looking as stock as possible.
Thought I'd ask what the collective thinks or suggests about the axle swap in regards to width.

Re: Converting M37 to D60 and 14ff axles

Posted: Sun May 15, 2011 4:41 am
by W_A_Watson_II
Depending on tire size, I'd recommend going as narrow as you can with out the tires are full turn/articulation contacting the body/frame/fenders/etc...

This will very likely be a few inches wider than the stock M, but not as wide as the D60 axle. To me going too wide just looks out of place, and screams non-stock, or over modified. I like the M's looking closer to stock unlike other vehicles modified for off-road use.

M M with the stock axles, but 17/10 wheels and 39.5x13.5R17's is just over 80" wide (aired down with bulge), and I'd hate to be any wider, as I'd have more trail issues.

Will

Re: Converting M37 to D60 and 14ff axles

Posted: Sun May 15, 2011 8:28 am
by Lebowski
Will,
My 1985 CUCV with 15/39.5" Swampers on 16.5x10 rims measures 84" tire sidewall to tire sidewall in the rear. I think the M37 data plate states 72" tire sidewall to sidewall. I agree overly wide starts to scream modified, and can detract from the original look. A narrow track will help resemble it's original character.

Re: Converting M37 to D60 and 14ff axles

Posted: Sun May 15, 2011 10:02 am
by Brett
Lebowski

The stock H1 rims are 9" wide, and have 7" of back spacing( just looked it up). this will effectively narrow the track width by 5" by moving the centerline of the tire inboard 2.5" from the wheel mounting surface of the hub. This however assumes that there will be no interference between the rim and the tie rods or other components.

Brett

Re: Converting M37 to D60 and 14ff axles

Posted: Sun May 15, 2011 2:34 pm
by Lebowski
Yes, correct about the backspacing, interference with steering components, offset, etc.. I would fun front wheel spacers (I think it is 1.5" spacers are needed) to run H1 rims on a non-dually style type frt Dana 60. I may put the dually style hubs on the front if I come across a set. Then I won't need spacers to mount the H1 rims. I'll have to check the spacer combo to use for the rear of the truck, depending which model rear 14ff I go with.
So overall I think I'll go for something that resembles the original M37 track width.

Re: Converting M37 to D60 and 14ff axles

Posted: Sun May 15, 2011 3:59 pm
by W_A_Watson_II
Here is a comparison I was during to determine my wheel new wheel backspacing.

Re: Converting M37 to D60 and 14ff axles

Posted: Mon May 16, 2011 5:53 pm
by Lebowski
Will, nice comparison. Thanks.
Did you lift yours at all?
So I am going to narrow the front. Glad didn't sell that frt D60 housing!

Anyone have some military looking rims to suggest beside H1 rims, that may look in character with the truck?

Re: Converting M37 to D60 and 14ff axles

Posted: Mon May 16, 2011 7:22 pm
by W_A_Watson_II
Thanks, and your welcome, they were from my planning way back when I started. Yea, I've got about 1" of extra short leaves, in the front installed in a new spring pack. At full angle articulation, I can just barley slip my hand between the tire and the bottom side of the top fender.

Re: Converting M37 to D60 and 14ff axles

Posted: Mon Aug 26, 2013 4:45 pm
by mp_tx
I know this is an older post. Did you (or anyone) ever complete this conversion? I am thinking hard about a CUCV axle swap for my diesel repowered M37 with NV4500 and passenger drop NP205. I plan on running H1 rims as well and would love to read or hear from the guinea pig.

Re: Converting M37 to D60 and 14ff axles

Posted: Tue Aug 27, 2013 11:41 pm
by Master Yota
I did this exact conversion (GM D60 front, full width, and 14B rear). I found it more cost effective to build new spring hangers and shackle mounts in the front than to try and narrow the long side axle. With the plethora of DIY brackets available now, its pretty easy to fab up some nice hangers. The rear is a piece of cake to install, all that is required is some narrowing of the spring perch for the ubolts to slide past on the 14 bolt and it will bolt right on. The stock M37 Ubolt plates fit the 14 bolt axle tubes perfectly. I had originally built the truck around the H1 wheels and 44's, a 1.5" spacer is required on the front to use stock H1 wheels on the non dually hubs in order to clear the massive D60 brake caliper. I needed a 3" spacer on the rear to match the track width (the 14 bolt is narrower) I used a regular truck rear diff, however if you can find one from a 3/4 ton van, it is wider and would either allow for a narrower spacer, or eliminate the need altogether... Here is how my truck looks at the moment, sporting 1100/16's on plain-jane steel wheels with no suspension lift at all (I managed to match the new front suspension to the OEM rear height...)
Image


If you search on here for "Project Old Guard" you can see the whole build with lots of pictures...

Re: Converting M37 to D60 and 14ff axles

Posted: Wed Aug 28, 2013 4:33 pm
by jimmy_stikx
I plan on doing this with my 6.2L re-power. Just have to figure out how to keep the floor mounted clutch.

Re: Converting M37 to D60 and 14ff axles

Posted: Wed Aug 28, 2013 4:59 pm
by Master Yota
jimmy_stikx wrote:I plan on doing this with my 6.2L re-power. Just have to figure out how to keep the floor mounted clutch.
In my current M37 (pic above) I used a set of hanging pedals from Uglytruckling that were designed for the civilian power wagon. They work just fine in the M37 if you swap the brake and clutch pedal side-for-side. The additional foot room was a major bonus with the switch to hanging pedals as well.

On my first M37 with a SBC, I simply used a stock "Z" bar mechanical clutch linkage from a gm truck and modified it to work with the floor pedal. It was ok for the most part. If you want to keep the floor pedals, I would look into a hydraulic clutch setup, then all you need the pedal to do is to stroke a small MC (cheap from Wilwood) and then use the right year (86-89ish?) gm bell housing with a hydraulic slave cyl...

Re: Converting M37 to D60 and 14ff axles

Posted: Thu Aug 29, 2013 10:00 am
by jimmy_stikx
Thanks for that info Master Yota.

Are you running wheel spacers with the plain steelies, or not?

Re: Converting M37 to D60 and 14ff axles

Posted: Sat Sep 07, 2013 9:54 pm
by Master Yota
jimmy_stikx wrote:Thanks for that info Master Yota.

Are you running wheel spacers with the plain steelies, or not?

No spacers with the 1100:16's....

If you do a search for www.TMRcustoms.com they offer a conversion bracket to use the smaller sized 3/4T gm calipers and rotors on the front D60. This would completely eliminate the need for spacers, as the H1 wheels would clear the brakes at that point.

Re: Converting M37 to D60 and 14ff axles

Posted: Sun Sep 08, 2013 2:10 am
by JimC
With my BBC, I just added an extension under the pivot point on the stock clutch pedal and used that to drive a clutch master cylinder mounted backwards beside the stock brake mc, which in turn drove the slave cylinder on the Chevy bell housing.