I've decided to do a Cummin's conversion

[EWC]

Gotcha , good luck with your project .

 

[FellowTraveler]

Gotcha , good luck with your project .

Thank's, is a bear of a job for sure.

 

[FellowTraveler]

Been slow going, I finally got the trans w/t-case removed and found a hole in my firewall looks like pry-bar did the damage last time trans was rebuilt. I finished encapsulating inside and out-side of chassis.

 

[n8in8or]

Been slow going, I finally got the trans w/t-case removed and found a hole in my firewall looks like pry-bar did the damage last time trans was rebuilt. I finished encapsulating inside and out-side View attachment 48876 View attachment 48877 View attachment 48878 View attachment 48879 View attachment 48880 View attachment 48881 of chassis.

That looks really nice! What are you encapsulating with?

 

[FellowTraveler]

That looks really nice! What are you encapsulating with?

Using Eastwood Chassis Encapsulator w/UV inhibitors, they make a kit to get into the chassis channel and nooks and crannies works good too. I was thinking of using POR15 but it degrades w/UV exposure.

You'll notice the motor mount chassis brackets are rusted at the ends "that's the sections that get cut off so 12 valve clears everything."

The Ram Cummins 47RH auto can be rebuilt on the bench w/o special tools meaning I can buy high performance inner parts and do it all myself for way less $$$$ than any GM or FORD trans.

 

[n8in8or]

Using Eastwood Chassis Encapsulator w/UV inhibitors, they make a kit to get into the chassis channel and nooks and crannies works good too. I was thinking of using POR15 but it degrades w/UV exposure.

You'll notice the motor mount chassis brackets are rusted at the ends "that's the sections that get cut off so 12 valve clears everything."

The Ram Cummins 47RH auto can be rebuilt on the bench w/o special tools meaning I can buy high performance inner parts and do it all myself for way less $$$$ than any GM or FORD trans.

Good info, thanks. Yeah I've watched POR15 turn to chalk when left outside without a topcoat.

 

[FellowTraveler]

Hit a snag, the 47RH 4x4 w/NP241DHD requires I go to SAS because I have a fourth member riveted to chassis rails just after the torsen bar member (GM upfitter manuals are void of this fact) and this 4th member supports the leading edge my aux fuel tank. I can use the trans/t-case member by moving it back "it uses the same trans mount the GM does." I suspect the 4th member is for additional support for 8.6k plus BURBS.

Been wanting cushy ride FORD HIGH PINION up front anyway using ORD's kit.

 

[THEFERMANATOR]

I wouldn't call any front leaf spring a cushy ride. Many are going with the late model 60's to retain ABS, and to go with radius arms and coil overs up front. Good luck finding a front 60. Unless you have one, be prepared to spend stupid money. Seen somebody wanting $1600 for just the housing(no knuckles or anything) for a 78-79 hp dana 60.

 

[snarl95]

would dana 60's from a mid 90's dodge 3/4 ton work

 

[THEFERMANATOR]

would dana 60's from a mid 90's dodge 3/4 ton work

You can use one of them. The 94-99 is a similiar width, uses almost 3xactly the same brakes, and is 8x6.5 lug pattern. Only drawback is no abs on any of them. The 00-02 went to much larger brakes with dual piston calipers, had abs, same width, and the same lug pattern. The late model 02's did away with tbe axle disconnect so the shafts spin all the time. Only drawback is Dodge speced them with small ball joints and rather light duty hub bearings(pretty sure they were almost the same as our hub bearings). There are places making hd ball joints for them, and hub bearing conversion kits. One can pick up a 00-02 Dodge dana 60, put HD ball joints in it and a free spin hub kit, and not be into it for much more than a 38 year old FORD high pinion.

The other popular option is the 05+ Ford dana 60 with radius rods. They're pretty beefy to start with, widely available, but you have a different lug pattern to contend with and have to run 17" rims to clearthe MASSIVE brakes. I wanted to build up a 2 door tahoe play toy and do a sfa under it, so I've researched them a bit lately.

 

[Jakec]

ive bought 2 '05 ford dana 60s for $300 each. badass 35 spline stock axles and huge brakes. you can redrill the front hubs to 8 on 6.5 easily. I have one of these axles under my jeep now and I have another one to put under my dually soon.

 

[THEFERMANATOR]

ive bought 2 '05 ford dana 60s for $300 each. badass 35 spline stock axles and huge brakes. you can redrill the front hubs to 8 on 6.5 easily. I have one of these axles under my jeep now and I have another one to put under my dually soon.

I know theres the company taking the 450 hubs, turning them down, then redrilling them for 8x6.5. Others get hub centric wheels that use lug nuts with flat washers, and just opening the holes in the wheels some too. And I know somebody else who bought a set of the free spin hubs but with the 8x6.5 lug pattern to go in his 01 1500hd. Or you swap both axles in since the 10.5 sterling isn't a bad axle and parts are reaso,eably priced, and just use the 8x170mm lug pattern.

 

[tanman_2006]

All ford calipers I've dealt with had a bad problem of seizing up on the pins.

 

[FellowTraveler]

I wouldn't call any front leaf spring a cushy ride. Many are going with the late model 60's to retain ABS, and to go with radius arms and coil overs up front. Good luck finding a front 60. Unless you have one, be prepared to spend stupid money. Seen somebody wanting $1600 for just the housing(no knuckles or anything) for a 78-79 hp dana 60.

I was thinking thinner springs for the spring packs. Any diff I get for an SAS conversion if I do it will not be of the sealed unit bearing type.

 

[FellowTraveler]

After re-examining the torsion bar x-member interfering with the big Dodge NP241DHD & the fact I have a forth x-member about 2” after it I’ve concluded the torsion x-member can be left in place and modified/braced for clearance of the t-case.

I had selected the Ram Cummins 47RH over the GM 4L80e because of the ability to build it to whatever specs I want all w/o special tools or computer to run it.

Simple hydraulic control w/ one wire for lockup and another for OD or use Hobbs switches and if any of those should fail I can still drive but with 3 forward and reverse gears only w/o damaging transmission. I do have a real low stall speed torque converter which prevents jack rabbit acceleration from a stop and I’m not building a drag racer so I’m happy with it.

Then there is the fact that the 47RH overdrive unit is 0.69 so with 295-75-16 & 4.10:1 gears the rpm’s are 2113 @ 70 mph as opposed to the GM 4L80e w/0.75 OD running 2297 rpms @ 70 mph that’s 184 rpm difference, then with 315/75/16e it will run 2048 rpms (or 249 rpm less than 4L80e) @ 70 mph.

Another option is change out the gear-sets to 3:42:1 and run 1763 rpms w/295/75/16 @ 70 mph where the 12 valve is happier however with a Burb wind resistance comes into play @ 45 mph +-.

I have not finalized what HP/TQ I’ll run but 550/600 ft. lbs. TQ would suffice for me.

 

[FellowTraveler]

Well, I'm getting the Cummins ready to install in Burb.

Killer dowel pin (KDP) is well known to vibrate out of its recess and break things, mine was out about 1/16th of an inch from being bottomed, I installed a new design retainer that if by chance comes loose it will not fallout or allow the pin to come out either because it is stopped by timing case cover too.

 

[Husker6.5]

That looks far better than the simple stamped/machined tab and retainer bolt most aftermarket vendors sell as a KDP fix.

 

[FellowTraveler]

I've been tearing down the 12 valve only to replace all seals and gaskets, cylinders & pistons are prefect cross hatching from honing is like it would be when it was done.

During tear down I found that someone plugged the pressure line from HX35W to the P7100 pump AFC housing. I'm replacing the plastic throttle shaft bushing with bronze. Running full 4" from turbine to tail pipe however I may go bigger on the muffler with a Donaldson 43" long by 11" diameter 4" in/out.

The 12 valve throttle cable connects to the GMC pedal nicely, the GMC transmission shifter cable will be used from front facing back to interface with the 47RH transmission, I'll being installing Dodge version of the TransGo HD-2 reprogram kit into the 47RH.

Tachometer signal will be via a transducer mounted to one of the fuel injection hard lines. The speedo I'll have to figure out in the mean time it will be GPS. Cruse control will be box cable type from GM gasser.

This conversion is a bear at my age with all my injuries but its a can do.

I had forgotten this Cummins is Navistar castings "endless highway logo" both block and head.

 

[n8in8or]

Sounds like good progress! What will you be using for the speed signal for the cruise control box?

 

[FellowTraveler]

Sounds like good progress! What will you be using for the speed signal for the cruise control box?

That's up in the air right now, the 47RH has a an electronic speed sensor but I'll have to figure what to do to adapt it to the VSSB.