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1991 GMC, bodywork, dually and 6.2 diesel questions!

MR4WD

1/2 ton status
Joined
Jul 28, 2002
Posts
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Location
Fort McMurray, Alberta.
I'm posting this in multiple forums looking for lots of feedback, so bare with me.

I'm looking at getting a 91 crew cab GMC. Last year for that style (V3500) It's pretty much the truck I've wanted since before I could drive, but it's single wheel. If I do purchase it, I WILL convert it to a dually, which shouldn't be a problem. The only thing I'm having difficulty with is finding aftermarket dually rims greater than 6" in width? I'd like to run 35's (the truck presently has 5 new 35x12.5x16's or whatever that works out to in metric terms) so I'd need to buy two more tires and 16x8" dually rims.

I realise that I could convert 6 or 7 16x6 steel rims to 8" fairly easily, but I'd like to run aluminum rims mostly for aesthetic reasons. I've sifted though a few websites, but manufacturers seem to concentrate solely on 16x6" wheel sizes? The other side of this is would a 35x12.5 run on a 6" wide wheel? I would guess no, but I've never seen or done this.

I can get outrageous deals on alcoa wheels, so I may go with (4?) new wheels and run a set of 36" michelins, which I could probably get for cheaper than a few new 35" bfg's. I'm aware those run acceptably on a 6" rim. While the tires will probably wear like iron, I find them a bit narrow for my tastes...

I have no requirement for an 8' bed, so I'll probably chop the frame and install a shortbox. Would dually flares fit on a shortbox? What sort of problems may I encounter?

I really have no experience with dually's in a personal environment. The truck I drive every day at work is a dually, and I usually make it my personal truck but I've never owned one.

Lastly, the truck has 60,000 miles on it and the original (no doubt!) 6.2 diesel. One of my work trucks had a 6.5. While quite enemic it was great on fuel, which is an underlying outline I have made. Down the road, I'll convert it to a 12 valve cummins and bomb it, but for now I'll settle for the fact it's got a 6.2 with an upgraded snail, down pipe and exhaust. What sort of power band do these engines operate in? The truck currently has 4.10's and a new 4L80E (with a 205!!). I shouldn't have a problem trading the SRW Dana 60 and 14 bolt for DRW versions, since everybody seems to have those. In OD, with 35's at 70 MPH I'd guess I'll be around 19-2000 RPM. Would the 6.2 cruise with a meagher load at that RPM? (a bed full of work gear for a few weeks) Or would it kickdown into drive all the time? An idea may be to trade up to 4.56-4.88s? I like to think of the 6.2 as a 350 that turns half the RPM, but I'm mostly unconfident and inexperienced with this motor...

Thanks from anybody who can offer insight with this truck,
Chad.
 
Congratulations on your purchase. I run 6" rims on my CC dually, so I'm not much help in that area but I'll be looking for responses from others. My 6.2 NA has plently of grunt to maintain speed at 2000 RPM with a load. My CC Dually K30 has a banks turbo and a TH400/Gearvendors (4:10), but my SRW K30 is NA with a TH400 (4:56). I do run a 4l80E in my K5 behind a 454TBI (4:10) and find it very stable on the highway.

There aren't too many guys here (if any) who run a 4l80E behind a NA 6.2L diesel. Although I have a spare 4L80E and have been looking for a 91-93 diesel controller for my SRW K30 in order to run that combo.
 
As far as the tires go....

You probably won't be able to find that large of diamater and width tires to fit on dual wheels. There simply isn't enough room to fit two tires that wide together under the bed and flares. Plus, the wheels are close to each other, leaving only a finite amounte of space to mount tires. You can't have dually tires touching each other, so that limits the width of tires you can put on it.

Stick with single wheels and large tires or dual wheels and narrower tires.

Casey
 
There are a few dually's running around here on 38's. I assume they have spacers between the inner and outer tires...or custom rims or???

Rene
 
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There are a few dually's running around here on 38's. I assume they have spacers between the inner and outer tires...or custom rims or???

Rene

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The tires you see Rene are 38x11 tires, swampers I am sure, and if not mistaken they are the boggers.
I was going to use these too but now I am thinking of staying with 35" tires, metric 85 series would put me at about 10" wide so I should be good with the 6" rims.
Now if you want to go with larger, like Arveetek said you need some spacers but that would probably put a lot of stress on the lugs, I am not sure I would like to do that to my axle.
/forums/images/graemlins/eek.gif
 
Sorry dude, when I'm sitting beside said dually in traffic, a bogger and a TSL are easy to discern. These were 38 x 12.5 TSL's. The guy was probably running a 1" spacer between the rims. /forums/images/graemlins/crazy.gif I'm sure he has no intention of ever loading the truck down with it like that.

Another good tire for the dually would actually be the ~39" Michellins. Roughly 10.5" wide and a tick under 39" tall. XML's? XL's? I can never keep them straight...

Rene
 
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Sorry dude, when I'm sitting beside said dually in traffic, a bogger and a TSL are easy to discern. These were 38 x 12.5 TSL's. The guy was probably running a 1" spacer between the rims. /forums/images/graemlins/crazy.gif I'm sure he has no intention of ever loading the truck down with it like that.

Another good tire for the dually would actually be the ~39" Michellins. Roughly 10.5" wide and a tick under 39" tall. XML's? XL's? I can never keep them straight...

Rene

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Well I did say I am sure they are swampers TSL is swamper, and if not mistaken (that means I am not sure /forums/images/graemlins/smile.gif ) it would be the boggers.
/forums/images/graemlins/grin.gif
 
[ QUOTE ]
Sorry dude, when I'm sitting beside said dually in traffic, a bogger and a TSL are easy to discern. These were 38 x 12.5 TSL's. The guy was probably running a 1" spacer between the rims. /forums/images/graemlins/crazy.gif I'm sure he has no intention of ever loading the truck down with it like that.

Another good tire for the dually would actually be the ~39" Michellins. Roughly 10.5" wide and a tick under 39" tall. XML's? XL's? I can never keep them straight...

Rene

[/ QUOTE ]

In my original post I had outlined a possible desire to run 36" Michelins. I have no desire for the extra lift required and gained by 39" michelins.
 
Since the thread in the towing forum is locked, I'll post the Cummins swap pics here. Note that I have removed the fan and shroud for the winter, but there is room for it. Not a lot, but it fits. /forums/images/graemlins/waytogo.gif
100-0001_IMG.jpg
100-0002_IMG.jpg
100-0003_IMG.jpg
100-0004_IMG.jpg
 
Mine has the same size Perkins 354ci TD and it fits just the same.
I had to put two fans one on each side of the water pump, the snout of which is 1" from the radiator and there is about an inch between the firewall and the engine in the back.
/forums/images/graemlins/yikes.gif
 
Perkins huh? Inline six? What are the torque and HP numbers for that engine? Just curious. I don't think I've seen one. Pics? /forums/images/graemlins/waytogo.gif
 
/forums/images/graemlins/bow.gif /forums/images/graemlins/bow.gif /forums/images/graemlins/bow.gif If I get the crew cab I'm wanting, I'm definitely going to try this after the current engine craps out. /forums/images/graemlins/bow.gif /forums/images/graemlins/bow.gif /forums/images/graemlins/bow.gif
 
For anyone looking at a swap, I have a spare 12V cummins with the P7100 pump available.

If I don't sell my '91 suburban I'll definitely look at pulling the entire drivetrain out of my '98 dodge and installing it in the 'burb. Use the 4sp dodge auto and either a GM np241 or older dodge '205 so I can run an older dana 60.
 
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Perkins huh? Inline six? What are the torque and HP numbers for that engine? Just curious. I don't think I've seen one. Pics? /forums/images/graemlins/waytogo.gif

[/ QUOTE ]

415ftlbs @800
170HP @1500
Max RPM so far 2300, I am working on tweaking it to 2800 or 3000RPM
 
Here is a link to the ad, Cummins ad

Take $300 off if you don't want the manual trans parts.
Possible atv trades, let me know what you have /forums/images/graemlins/laugh.gif.
 
[ QUOTE ]
[ QUOTE ]
Perkins huh? Inline six? What are the torque and HP numbers for that engine? Just curious. I don't think I've seen one. Pics? /forums/images/graemlins/waytogo.gif

[/ QUOTE ]

415ftlbs @800
170HP @1500
Max RPM so far 2300, I am working on tweaking it to 2800 or 3000RPM

[/ QUOTE ]

Not too shabby. /forums/images/graemlins/thumb.gif
 
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How many miles?

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Around 100K, per the yard that pulled it out of the truck.
They had it running before it was pulled and I fired it after I picked it up.
 
[ QUOTE ]
[ QUOTE ]
How many miles?

[/ QUOTE ]
Around 100K, per the yard that pulled it out of the truck.
They had it running before it was pulled and I fired it after I picked it up.

[/ QUOTE ]

Just about broken in then. /forums/images/graemlins/grin.gif
 
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