M1008/1028 optimal tire sizes to offset 4.56 gearing

[Adamlee]

Fellas, just a quick Q. What is the sage advice on managing the 4.56 ratios on M1008's....via tire selection....

can 38's, 40's, or 44's successfully offset the high gearing to net a more fuel-friendly 3.23-3.55 ratio?

just wondering what people have done to offset the high gears prior to getting new gearsets....

Adam

 

[Westech]

I had the hummer 36" tire and it was good on the high way.. 60 no problem..... CC uses a 38" tire and he says thats just about right with the power of the engine and the axle gears.

 

[FMJ]

I have 33's with a 4" lift 65-70 mph is no problem

 

[Westech]

65/70 with 33' tires and 4.56 gears? that would be 3018 RPM at 65 MPH..... ah.. hope you keep stock in 6.2 engines.......

 

[Hoot_223]

37" tires

 

[CCATLETT1984]

FMJ your gonna kill that engine with revs that high.

I think that anything over a 38" tire is just gonna rob the low end from the truck. you'd have to put a trans with a lower first gear to get going. anything from a 36-38 would be a good size to drop the rpm's without sacrificing power. If you still to a narrower tire you can fit them with less lift and trimming.
I run 15" wide tires so i had to lift the truck 6" and trim just a little bit from the rear of the front fender openings.

 

[K10A]

39" MICHELINS are just about perfect.

 

[BKubu]

Adam, you've probably already thought of this, but if not, here goes...why not put an overdrive kit on the truck? John Winslow has one on an M1028 and, man, does it make a difference. We were cruising along at 75-80 mph at the same RPM that would normally get you about 50 mph. The kit is not cheap...$2500 not including installation...but it is worth it if you are looking for higher highway speeds. If I keep my M1028 for a while, I will consider it. By the way, CUCVFAN knows much more about this kit than I do, so you may want to contact him for info if you are interested.

 

[aboonski]

Sounds like a Gear Vendors overdrive unit made in California. You can buy a kit that bolts directly to the transmission/transfer case for the CUCV and yes it is expensive! With diesel running $3.50 a gallon here in Florida, a person would quickly recuperate from the cost of this overdrive setup especially if you drive your MV every day like I do.

 

[FMJ]

Re: RE: M1008/1028 optimal tire sizes to offset 4.56 gearing

65/70 with 33' tires and 4.56 gears? that would be 3018 RPM at 65 MPH..... ah.. hope you keep stock in 6.2 engines.......

Whats considered acceptable for the upper RPM on a daily driver?

 

[Westech]

RE: Re: RE: M1008/1028 optimal tire sizes to offset 4.56 gea

like 2500 RPM

 

[aboonski]

RE: Re: RE: M1008/1028 optimal tire sizes to offset 4.56 gea

www.gearvendors.com/index.html is the address for the overdrive units. The price they quote for the CUCV application is $2895.00. If they install it and modify the driveshaft for you the additional cost is $650.00. Their address is GEAR VENDORS, INC. 1717 North Magnolia Avenue, El Cajon, CA 92020
Toll Free 800-999-9555 • Telephone (619) 562-0060 • Fax (619) 562-1186

 

[FMJ]

Re: RE: Re: RE: M1008/1028 optimal tire sizes to offset 4.56

like 2500 RPM

Looks like its time for a 700R4 from Bowtie Overdrives, cheaper than Gear Vendors.

 

[aboonski]

RE: Re: RE: Re: RE: M1008/1028 optimal tire sizes to offset

I'll have to look them up on the internet. Eventually I want to put some kind of an overdrive in my M1008A1. I have five K5 Blazers in the back yard and four of them have the 700R4 transmissions. I think the Gear Vendors unit allows you to shift into an underdrive ratio lower than that at the rear of the transfer case but not sure. Once you go into low range in an M1008, you don't really need to go much lower!

 

[mangus580]

Re: RE: Re: RE: Re: RE: M1008/1028 optimal tire sizes to off

I'll have to look them up on the internet. Eventually I want to put some kind of an overdrive in my M1008A1. I have five K5 Blazers in the back yard and four of them have the 700R4 transmissions. I think the Gear Vendors unit allows you to shift into an underdrive ratio lower than that at the rear of the transfer case but not sure. Once you go into low range in an M1008, you don't really need to go much lower!

What year are the blazers that have the 700R4.... I would have one of them rebuilt for a diesel... and put it in your 1008 in a heartbeat!

 

[aboonski]

RE: Re: RE: Re: RE: Re: RE: M1008/1028 optimal tire sizes to

I have on 1989 that has been rebuilt and shifts very tight and another rebuilt one in an 87 which now has no body on it. My 1983 K5 has a very weak 700R4 that needs an overhaul but still shifts into every gear and I have another 1989 with a 700r4 that is toast because the previous owner never checked the fluid level in the transmission. Which one would you have rebuild into a diesel tranny?

 

[mangus580]

RE: Re: RE: Re: RE: Re: RE: M1008/1028 optimal tire sizes to

Well, the good 89 might work just fine with a new Torque Converter, and Governer.... Otherwise, my next choice is the bad 89... stay FAR away from the 83.

 

[aboonski]

RE: Re: RE: Re: RE: Re: RE: M1008/1028 optimal tire sizes to

Thanks for the info! I'll start looing for a shop to have the work done. Probably the most reasonable way to get an overdrive for my CUCV. I have heard that some of the earlier 700R4s were not too good - plastic parts, etc. I think there was a post where someone replaced their M1008 stock tranny with the 700R4. I'll go back and do some research.

 

[mangus580]

RE: Re: RE: Re: RE: Re: RE: M1008/1028 optimal tire sizes to

Search for posts by me about it.... I have an R4 in my 1009.

 

[FMJ]

I've done the 700R4 swap also. I did it to a 78 Chev K10, took out the TH350 and swapped in a 700R4 from BTOD, its behind a 400 hp 454 with 3:73's it's got about 20000 on it so far, no ptoblems. The 700R4 was just a bit longer than the 350 so the crossmember holes were redrilled, front DS lengthened, rear shortened. They include a lockup switch so you can tow in third gear without burning up the tranny. I'm very happy with it, so happy that the setup may end up in my 1008.......