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I've decided to do a Cummin's conversion

Nosferatu49534 said:
How would you know what was missing? You didn't design it.... Lol. Some people won't except help even if they're wrong. [emoji15]
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Will, is pointing out that the GM upfitter manuals are missing parts "components" in their illustrations that are actually on the vehicles, he submitted corrections which is common so the manuals could be updated with correction, and was ignored.
 
FellowTraveler said:
Will, is pointing out that the GM upfitter manuals are missing parts "components" in their illustrations that are actually on the vehicles, he submitted corrections which is common so the manuals could be updated with correction, and was ignored.
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I know. [emoji4] I wish there was a sarcasm button. [emoji2] it would make being a smart a$$ way easier. Meant do disrespect.
You guys are geniuses in my book for sure.
 
Flooding hit yesterday it was a mad rush to place everything up high good thing the flooding stopped at the edge of the house.

Now my engine crane has stopped working with the Cummins sitting above the frame rails and can't swing it onto the mounting pads, it started moving less and less as it was pumped until it just stopped, I suspect low fluid hopefully I can put some fluid in today and get it working again.

I'm in high gear now with the t-case to finish then shafts and wiring....
 
Well today no high water, so I test fitted the Cummins and found a problem with it hitting the front differential on drivers side, spacers are out of the question because that would put too much rear downward angle in the drive-train.

I'll be dropping the front differential 2" with an aftermarket kit.
 
FellowTraveler said:
Well today no high water, so I test fitted the Cummins and found a problem with it hitting the front differential on drivers side, spacers are out of the question because that would put too much rear downward angle in the drive-train.

I'll be dropping the front differential 2" with an aftermarket kit.
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And that was the issue with running a solid front axle and not enough lift from what I read from those who did them. The 36.5" wide spring perch axle would give more clearance, but then you have to use the offset spring perch mounts, and I wasn't fond of how they atatched to the frame.
 
THEFERMANATOR said:
And that was the issue with running a solid front axle and not enough lift from what I read from those who did them. The 36.5" wide spring perch axle would give more clearance, but then you have to use the offset spring perch mounts, and I wasn't fond of how they atatched to the frame.
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One person has suggested slotting the block motor mounting brackets even further to clock the diesel more to the drivers side to clear the differential, I'll have o determine if that will cause other fitment issues.
 
If you clock the motor, the transmission and transfer case have to clock with it (unless you want to machine a very expensive one-off engine to transmission adapter that keeps the tranny and transfer case in their original orientation) which means the transmission mount/crossmember would have to be custom made to allow for the new mounting angle. There could be floor pan clearance issues or ground clearance issues with the transfer case, as well as shift linkages for the transfer case (it is mechanical, not electronic, isn't it?), too. IMHO, easier and cheaper to install a differential drop kit.
 
Husker6.5 said:
If you clock the motor, the transmission and transfer case have to clock with it (unless you want to machine a very expensive one-off engine to transmission adapter that keeps the tranny and transfer case in their original orientation) which means the transmission mount/crossmember would have to be custom made to allow for the new mounting angle. There could be floor pan clearance issues or ground clearance issues with the transfer case, as well as shift linkages for the transfer case (it is mechanical, not electronic, isn't it?), too. IMHO, easier and cheaper to install a differential drop kit.
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According to the GM Upfitter manuals all GMT400 engines gas/diesel are 30 mm off center to passenger side of chassis center line and clocked 5 deg. down on drivers side however; WILL has stated there are errors in the manuals that GM refused to correct and FERM fortunately has corrected me on some mis-information in the manuals too.

YEP, My drivetrain is all mechanical Cummins, Dodge trans then GM t-case I already have to clock, I'm doing the differential drop and now wonder if the axles CV joints will wear faster bringing them so close to center.
 
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UPDATE GMC K2500 SUBURBAN CUMMINS CONVERSION AKA: “SUBRUTUS©”

Well, I’ve been out of pocket for some time now, however, I have been making some progress and decided the need for an ORD SAS conversion w/custom thin spring pack too compliment this conversion.

The Cummins 6BT is installed, the DODGE 47RH 4X4 transmission is finished and ready for install too but I ran into a few issues.

First is that the IFS 9.25” differential needs to be lowered “too close to the Cummins oil pan for my liking” then the case needs to be ground down at the reinforcement ribs to make it fit which in turn reduces the case strength “something I’m not willing to live with.”

Secondly, the Torsion bar cross member would need to be modified & lowered because I’m using the 47RH 4x4 transmission (wide-box) w/clocked NP241 t-case. The amount of drop & fabrication would also require at last a 4” to 6” suspension lift, so instead of going this route an SAS conversion using ORD’s kit and a high pinion D-60 Ford diff is money better spent especially since ORD makes custom thin spring packs for the Cummins conversions.

The Cummins weighs 300+- lbs. more than a 6.5td depending on accessories (increasing sprung weight) and some vendors of conversion motor mounts have stated in their install instructions “to cut out the two diagonals chassis braces attached at the front x-member and to the chassis uprights” for the conversion that is a bad idea as it compromises the chassis designed strength. For my install I’m leaving them as not too compromise the chassis strength, however, I had to cut the passenger side diagonal and weld in a modified bowed section to clear the Cummins, the steel rod used has strength well beyond the hollow unit GM installed during manufacturing.

I haven’t weighed the front 9.25” IFS differential, CV axles, control arm’s, tie rods, center rod, idler bracket & arm, brackets (too be cut off chassis), hardware, torsion bars and t-bar x-member I suspect it will be well beyond the difference of the Cummins to GM 6.5td weight. Selling these items will put a large dent into cost of the SAS conversion.

I’ve found two exhaust down pipe options that work perfectly with the CHEVY/GMC Cummins conversion clearing the firewall, AC accumulator & dual heater lines on later model GMT400 it’s the Cummins center mounted turbo exhaust manifold which places the turbine between # 3 & 4 cylinders (factory or aftermarket).

1st OPTION: Is the 1st gen Ram Cummins 2wd down pipe in 4” diameter for the HX35 & (w) or HX40 & (w) which is available in 4” or stock HX35 turbine outlet size and stainless too.

2nd OPTION: Is the original Cummins Design Cobra Head 4” down pipe (rare) “for utmost exhaust downpipe flow” it hooks up to all HOLSET/CKO HX40 (W) & Super 4” full Marmon turbine outlets then attach a 1st gen Cummins 2wd 4” downpipe trimmed to fit. Both of these options work well with dual HVAC option on the later model GMT400 Cummins conversion all other downpipe options are full custom.

NOTE: Earlier dual HVAC equipped GMT400 use a metal manifold pipe assembly for the heater hoses and does not work, some individuals have used the manifold that places the turbo down low & back between # 5 & 4 cylinders this is OK for stock Cummins tunes however from what I have read from many sources if using this type of exhaust manifold and pouring on the fuel EGTS @ # 5 & 4 cylinders will skyrocket into piston melt-ville……

Pondering exhaust break and/or large mechanical 12”+ t-case yoke disk brake for those steep mountain descents.

Throttle cable to the BOSCH P7100 Injection Pump is an updated Ram Cummins item trimmed to 21” on the pedal side for the GTM400 conversion.

The DODGE 47RH (wide-box) transmission is shifted via the stock late model GMT400 column shifter cable assembly. Normally the GMT400 auto shifter cable is routed towards the back of vehicle then looped through the drivetrain hump to connect to the GM transmission and shifting in a pulling motion, the 47RH shift pattern is opposite to GM so the GMT400 shifter cable is routed through the firewall just left of where it exits the steering column the shifter cable is then looped and routed along the inside of fender well under the ABS lines and module bracket out under the driver side battery tray then looped back and down along the chassis rail then attached to the custom cable bracket I made from the 4L80e shift cable bracket.

The GMT400 shifter cable is looped at about the same angles as it would be for the GM transmission so I expect long life from it, the custom shifter cable bracket (picture in earlier post) is mounted horizontally to the bell housing bolt just under the starter hump on the transmission where the cable is then snapped into place allowing it to shift the Dodge 47RH simple and cheap.

The stock RAM CUMMINS throttle valve cable is used in this application.

I cut the drivetrain hump for the driver’s side NP261 t-case shifter the linkage or NP241 lever will need to be modified. I’m using a three (3) pin shift switch on t-case however a two (2) pin switch will work with the 47RH, NV4500 or NV5600 as well, 40 tooth tone wheel is a must for the speedo.

I’m using the DODGE RAM CUMMINS radiator and charge air cooler aka intercooler the radiator inlet interferes with the driver’s side battery, however I have cut off the outer edge of the tray at the fender well and slightly dented the rear most corner of the driver’s side wheel well where it meets the tray giving the battery room to fit in w/same gap between radiator intake and battery it would have if I was using the GM radiator.

An air-filter canister “water & dust proof” w/5” canister inlet from 6” oval pipe snorkel and 4” outlet to 4” turbocharger compressor inlet will be used.

Mulling the idea of using the 6.5td glow solenoid to engage the Cummins grid heater (s) or just go w/momentary switches leaning towards less electrical accessories even using cable control for fuel run/stop.

I’ve read some individuals have used the 6.5td lift pump in series with the 2nd gen. Cummins mechanical lift pump with good results maybe I’ll try it too.

As usual your thoughts and comments are welcome.

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If the only reason you're running a gm transfer case was the speedo, there was MUCH simpler ways of making that work. You could have used a dakota digital speedo box and the stock dodge hall effect speedo pickup, and made it work then you wouldn't need a clocking ring or anything else.

You couldn't pay me to keep the crappy stock lift pump in place. The stock 5.9l lift pump is the same one that was factory offerred on the 450HP 8.3l, so why run a pump that can only move 30gph on a good day free flow.

As to your grid heaters, any cummins dealer can get you a generic controller for it. Either that, or you can run the early controller that dodge used. Ford starter solenoids work great for these applications if you go with manual control.
 
I have a question, why are you going with the early Ford Dana 60? I know on craigslist I see people selling boat anchor ones of the 77-79 style for $2000-2500. Unless you're planning on running a tire taller than 36-37 inches tall, theres really no advantage to running a 77-79 vs the later 85-91.5 style. In fact theres several disadvantages to the early axle that I've seen talked about.

The 1st is obviously the cost difference between the 2 axles because everybody is convinced the need 12 inches of lift and 44's, so they gotta have that uber rare axle. Then theres the amount of lift you need. The 85-91.5 axle moved the diff furthur out the tube allowing the axle to be able to comeup higher before coming in contact with the engine. I would think with the cummins hanging down, having the diff furthur out would be a HUGE deal in giving you extra clearance. Other than the diff being moved furthur outwards moving the spring pads out, they're the same axles right down to the king pins. I believe you can even mix and match parts around and add abs sensors to the later axle if thats of interest to you.

Or if you have any interest in retaining abs, why not run the 00-04 Ford dana 60? Yes it's a ball joint axle with unit bearings, but they're beefy, and proven to hold up to seni large tires for decent life spans. Or for what you'll sink into a 77-79 axle by the time you buy one, regear it, rebuild the kingpins, rebuild the hubs and such, steering, and all the rest(most sites say to figure at least $4K by the time you get one ready to install, if not $5-6K if it needs repairs), you could pick up a late model super duty axle, regear it, install rebuildable ball joints, manual locking hubs, and have a 20 year newer axle that is as strong or stronger AND retain your abs.

Just would hate see you spend all that money on one of the impossible to find dana 60's when a much easier to find and cheaper one is more than enough, and may even be a better option for a space limited application.
 
The transmission I’m using a Dodge™ 47RH is longer in 4x4 configurations than the 47/48 RE’s but it will clear the fixed cross member after the torsion bar cross member I’m happy with that.

The 47RH performance parts are a fraction of what the 4L80e performance parts were when I did that transmission. I picked the 47RH solely on the fact that it was hydro operated with only the need of switches for the OD/LU at a minimum I went redundant there with a Comp Mini controller for the OD/LU too. I have an awful amount of time in getting the valve body just where I want it and upped the clutch/steel counts; billet parts, TransGo™ & Sonnex™ odds & ends make life for the 47RH behind my Cummins™ build easier finished with the addition of a good torque converter to complete the package.

Considering, buying a used Dodge™ NP241D or DLD transfer case or just the Dodge™ front case section (new) to bolt up to the back half of the NP241C eliminating the need for a clocking ring the NP241DHD will not work w/o removing my aux fuel tank and reworking the fixed cross member.

After reviewing FERM’s comments I’m looking now for 85 to 91.5 FORD™ DANA™ 60 because the pumpkin is moved over to the driver’s side more than the earlier FORD™ DANA™ diffs making for a shorter d/s diff tube and a longer p/s diff tube general consensus is that gives a little more clearance between pumpkin and oil pan but not sure here but I’m hoping it does in fact since the Cummins™ sits at the same degree as the 6.5td did into passenger side of chassis center line.

Someone even mentioned ¾ ton FORD™ DANA™ 44 out of an F250™ for more clearance however it’s short on capacity IMO.

I’ll be using the ORD™ SAS conversion kit which has a 3” lift built into it then use their 1” spring kit along with x-over steering link “hopefully keeping the total lift down on the low side”, an ORD™ shackle flip will complement in the rear.

I had talked to one of the reps at ORD™ a couple of days ago about my build plan and when I have more information I’ll post that.

A good amount of sprung weight to be eliminated by removing all IFS suspension, IFS diff, all steering linkage & idler bracket, all of the welded control arm & diff brackets, torsion bars and t-bar x-member will keep factory box.

As I’m hunting down a buying all the parts to do the SAS I’ll be driving SUBRUTUS© on shakedown cruises in 2wd configuration by simply changing back to the 47RH 2wd OD tail shaft and install extra clutch count clutch packs too, I’ve already dis-assembled the axle CV to use the splined section to hold the sealed bearing unit together while I go 2wd yes it will be a little extra cost for 2wd driveshaft but at least the Burb will not be sitting parked while I gather all the SAS parts.
 
Theres a 94 ball joint one on craigslist now for $1K, and somebody in ocala with a kingpin model, but he has a 14 bolt and 205 packaged for $2K. I think I seen one on facebook for $1K last week for a kingpin. I also saw a 79 f350 complete rolling chassis for $2500. I think you can get one of the late 70's 44's from under a f250 camper special which is a beefy axle.
 
THEFERMANATOR said:
Theres a 94 ball joint one on craigslist now for $1K, and somebody in ocala with a kingpin model, but he has a 14 bolt and 205 packaged for $2K. I think I seen one on facebook for $1K last week for a kingpin. I also saw a 79 f350 complete rolling chassis for $2500. I think you can get one of the late 70's 44's from under a f250 camper special which is a beefy axle.
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Thanks for the response FERM; I’ve decided anything FORD past 91.5 is going to be more fabrication than I would want to do then there is the problem that ORD does not offer a kit to do cross-over steering on FORD ball joint 60’s.

I noticed you mentioned the heavy duty F-250 DANA 44 but I’ve been concerned it is not up to the task under the Suburban or am I just over thinking this. I don’t beat on the Burb and off road I like to mosey slowly down the trails.

The problem I’ve found to be common when using CL is that most people are all over the place on what they assess the condition of drive train components are that they sell on CL “POR 15 over badly rusted and pitted differentials is commonplace” I’ve been on more than a few long trips only to be disappointed when I see it in person.

Man I am glad the hurricane didn’t come to my AO and put me back to redoing everything on the Burb all over, I hope all affected in Texas make the best of a bad situation I can tell you coastal floods are a bitch and the damage and stench lingers for a long time.
 
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