MunK

Hello all...

This spring I plan to take the plunge and convert our 1985 W350CC to a Cummings powered truck. My donor is a 1992 D350/5spd with a sweet running 100k mile engine, and a broken Getrag. I could use some advice..ideas so here goes.

The crew cab presently runs 38" tires and 4.56 gears. I refuse to re gear this truck (already runs front and rear Detroit's) So... considering this must be somewhat budget minded rebuild of a well loved old truck I am trying to debate between searching out a Getrag/205 combo or a 727/205 combo. The truck at present runs a 727/205. Obviously my wish to not re gear will make for one slow truck if I run a 727. My question is... are the Getrag/205 combo's difficult to source?...I have yet to find one?

Driveshafts: I presently run 1350 Joints front and rear with custom shafts...any reason to think these would not hold up? Or should I swap to 1410's in rear now? They have held up to a honest 475hp big block now for years.

I plan to bomb this combination about as soon as it's in running condition. I am shooting for as much HP/tq as reasonable and still retain the ability to hook some weight on the back. I have built plenty of "played with" gassers in my days but this is my first dive into something that is suppose to smoke LOL

Any ideas that will save me work/money/frustration in the future that you can suggest while doing the swap, I would sure love to hear about. All I know of so far is a 3200rpm spring, a power stroke IC, 4" exhaust, and at this point I am out of ideas on whats the best bang for the buck.

The Cummings I am using is basically OEM with some "40hp injectors (previous owners words) and a rebuilt injector pump at 102K miles due to sitting a lot. The engine runs great, uses almost no oil, and in general I think can safely be assumed it's solid. I used it rather hard when we moved and it never once whimpered...although the Getrag did go south on me....but from what I have read, I should get a properly built one to live much better.

The truck is used hard off road..it works for a living. It also may be expected to handle cross country towing, and about anything in between.

Dodges specs as it sits: 500" big block/727/205 Dana 60 front with 35 spline Yukon shafts inner/outer/4.56 Detroit/Chevy Brakes. Rear axle is a Chevy 14 bolt/Detroit/Disk brakes. There plenty more but thats the basic running gear.
I am going to toss the engine and transmission from this one into a M37 so it's kind of like recycling.



NoRM
willing to listen to any ideas

G1625S

Welcome to DTR! Nice to have you along--it looks like you're building the truck lots of us would like to have

Before I give my thoughts, let us know what kind of use the truck will see. 'Work' is a vague term. 90mph on the freeway towing? Hauling stuff up old logging trails at .5mph? Either way, the gears are gonna hurt 'ya, but in any event, let us know the average intended use so it'll be easier to offer suggestions.
greg

rbrettctd

There are plenty of trucks out there with Getrag/NP205 combos behind the cummins. You are right, 727 would make for a slow truck. I think with 38s/4.56 thats about the equivalent of 32s/3.73, judging by my buddys old burb that was regeared and lifted. 727/3.73/(4.56 with your tires) would only be good for around 50 or so. Throw a GDS h1c upgrade in your mod list and youll have a good running truck.

G1625S

Oh, BTW, there is no 'g' in Cummins

MunK

Thanks for the welcome... and may I wish you best of luck on continuing head gasket/head issue.

We have owned the truck 4 years now and 185K miles. (have freshened the big block twice) The 360 didn't last long. Had 20K on truck when we bought it it's a old USAF truck.

The truck has seen mountain snows almost hood deep chained on all 4 corners. It has seen water to mid windshield. (snorkel in plans) Lots of mud (It has been used a lot for hunting/fishing/logging/exploring) It has wheeled in Moab,Colorado,South Dakota,Minn,Mich,Nova Scotia and many other places..It has towed a enclosed toy hauler all over the country, hauled a 60' trailer home up a hill a tractor couldn't, took the kids to school, driven from Wisconsin to Seattle and back in snow, and plenty more...I am not at all easy on it and tend to think of it as a high speed tractor thats invincible (I know better and the broken parts pile proves this lol)

And I usually keep it to 80mph on the freeway..;-P

NoRM

JD730

Do you have anything against the overdrive automatics? I would not mess with an A518, I'd go right to a lockup 47RH, built of course. How much of a budget are you on? Buying the parts to built a 47RH right is not cheap.

What about a Getrag/divorced 205 setup?

G1625S

Hehe, thank you for your honesty and for you good wishes on my ill-fated HG adventure I guess what I'm looking for is the average usage of the vehicle. For instance, over the course of a tank of fuel, what is the main use? The narrow RPM band of a 12V dictates a compromise somewhere...oh, and step up to the 1410's. A 'paltry' 300 RWHP 1st gen Cummins will produce axle snapping torque that a BB Chrysler can only dream of...and I've owned a 361 and a 413, so I can appreciate the grunt of Mother Mopar

JD730

Good advice, I broke the yoke on the dana 80 in my 2000 towing, didn't break the cross, I also sent a damping spring out of the disc. 300hp will put it in the 700 to 750 ft lb. torque range around 1800 rpms.

MunK

Well......... the 47RH is not a known entity to me so I have very little opinion...if it has electronics though admittedly it's less attractive. You never know when I might do something real dumb with the truck...It's happened a few times.

The last time I drove it was the last tank of fuel it went as follows.
We were in the middle of a Wis blizzard... about 14" of wet heavy snow and 40 mph winds. My neighbor was stuck in his driveway with his 2006CTD Dually..never missing a chance to impress myself (no one else really pays attention) I spent 20 min turning it like a Winston cup engine clawing to his truck and dragging it out. (should have chained it) Then I went home chained it and spent 4 hours clawing 12 miles through fields, ditches,you name it (roads were plugged) to get my X wife her meds she apparently forgot to buy BEFORE the storm. Only winched 5 times.

That eve my Gal and I spent on the lake whipping donuts in 4x4 while sipping margaritas and discussing the finer points of life (air powered blender) the following day we left with it and trailer to rescue my son who was stranded in Colorado with his dead Mustang. It see's rather normal usage hauling kids to school, car parts, dragging trailers...it really does almost everything. I broke the 205 in half almost so it's sat now for almost year...we are going back to Wisconsin to drag it home here this next week and begin a ground up rebuild....I plan to spend a few months in Alaska with it this next winter.

I could re gear 3.73 I suppose and 727 it with the 38's but I fear that would be hell on the transmission. I am starting to think I just need to find a Getrag/205 combo. Has to be one reasonable someplace.

As for 1410's if you feel thats a prudent idea that 1480's it will be....I like insurance.

NoRM

wannadiesel

That's a good suggestion, how broke is the Getrag?

If you are going to keep the 4.56's you absolutely MUST have some sort of OD on there.

Mike's other suggestion of a 47RH is a great one, that trans has a 0.69 OD ratio which will really help those deep gears. The 47RH does not need electronics to work, a couple of switches (one for lockup, one for OD) will suffice for a driver who knows what he's dealing with. There's a nice writeup in the sticky on how to control the OD with a pressure switch in the governor pressure test port, that would bring you down to one switch. And I don't see any reason why you couldn't tee in and use another (lower pressure) pressure switch to run the converter.

The other possibility is a 727/205 combo with a Gear Vendors OD on the back. You don't get OD in 4wd, but who needs to go 70 mph in 4wd?

MunK

Not sure how broke the Getrag is...I have no third, fourth,fifth gears..everything else seems to work. It made some very discomforting noises when we were towing so I have a suspicion it's far from healthy. But if I was rebuilding it a conversion to a married style transmission output would be easy...but I would still need a case and adapter/spud.

As for the automatic idea... a 4spd with no computer doesn't scare me...but again I would most likely need a donor, what years would I be looking for then?

I do like the idea of an automatic in some ways....but ya can't argue the simplicity of a stick...but I suspect by the time ya figure a good quality clutch they may not be all that far off in price.

I have a fella here local who has a 92 W350 single wheel truck for sale... 200k with a NV4500 swapped in 10K ago no title I could buy as a parts truck and I have considered it many times...but I not sure what I could get for the spare 6bt then to offset cost.

NoRM

Free89W350

1994 and 1995 cummins or v10. You will also need the motor plate and possibly more. I'm sure someone will chime in on what. I myself am trying to gather the parts for the 47rh swap.

wannadiesel

You ought to be able to get at least $1500 for a running 6BTA, plus the miscellaneous other pieces you can sell off the truck. The other plus would be that you could swap in those axles for an easy regear.

Featherman

Norm................I sent ya' a pm. Will wait for your response.

torquefan

That sounds like a perfect solution. You could sell off everything you don't end up using and maybe even come out ahead.