1989 Suburban Beast

[Kngjmz]

Hello everyone. Got the 89 Suburban V2500, 5.7l, TH400 with full suspension rebuild, along with steering and brakes. Thinking of pulling dually rear from yard to covert to dually, so any suggestions on that and increasing mileage with the 4" lift and 35" tires on 17" American Racing Rims?

Thanks for any info. God Bless.

James

 

[MrMarty51]

Hello KNGJMZ. Welcome to the forum.
I’m not knowing much about duallys, just seems that duals would increase fuel consumption.
I believe that there was a dually version of the Suburban from the factory but I think it was a rare item.
Possibly better snag the rear fenders from whatever vehicle You pull the duals from. I might be wrong in my memory banks but I think thats what the Suburban I seen had on it.
Need to also check the differential to be sure it is geared the same as the differential in Your vehicle, if it is a four wheel drive.

 

[MrMarty51]

The wheels on this one looks like .

 

[WarWagon]

You need an "up-fitter" to make this DRW change ... because they are the ones who did this in the past and have the liability insurance to change the door sticker GVWR, etc. Otherwise why bother adding two more expensive tires to wear out with a wider and rougher ride. (As an example our 2020 GMC 2500 Van has an upfitter sticker that specifies diffrent tire inflation pressures than OEM. Although common for cutaway vans this is a normal van modified for mobility.)

I'd spend the money warming up the 350 and transmission to 'handle' the warmed up engine.

@Will L. will be along shortly about the larger tires. Just saying the number of bodies on the freeway with a blanket over them from a old lifted pickup with big tires that had rolled held me up quite a while delivering an RV to auction a long time ago. They were not run flats and left quite a bit of tire debris on the road prior to the scene.

 

[Will L.]

Please describe what you are trying to accomplish with the truck. just look cools? Obviously not really trying to improve towing with that engine. “V”2500?
Those tires and lift wreck any additional stability gained by the duals.
Have to talk to trans guy about the different speedo gear needed in the tailstock. I suggest driving it before you get that part done to make sure you’re happy with the axle gearing first.



Legal theories are out the window if you diy. Almost no FDOT rated shop that can assume the liability will touch a truck that old for reclassification unless they strip it to the frame and build it all themselves to correct and replace issues as they go. In many states someone could rear-end you from them following to close and you can be found at fault. I was co-owner in one of the upfitter companies he mentioned above.

 

[EWC]

V2500 is when Chevy went to the new body style and changed the older square body to the RV model . V 2500 is 4WD and 3/4 ton . Tires are the same on my 91 V2500 and my 86 CC dually . I have seen the dually Suburbans but I want to say the dually fenders came onto the rear door so they are not the same as regular dually fenders .

 

[MrMarty51]

I expanded the pics I posted. The rear fenders are not a part of the rear doors. They do come right up to the back edge of the door.

 

[JayTheCPA]

Welcome to TTS!

IIRC, GM's dually configuration from that era were an attorney's manna from heaven as the brakes were under-powered which resulted in collisions when loaded heavy.

As noted, the stated plans are known to have the opposite effect on goals, so please help the community understand where you currently are with the project.

From a practicality standpoint, I have not noticed any difference between a single and dual rear when it comes to towing into the 9K# range or hauling up to the payload rating. The game changer is a transmission with at least 5 forward gears as 3 or 4 speeds just make the engine work a lot harder. 6 speed trannies seem like the sweet spot and have not tried anything with more gears than 6.