Pirate 4x4 banner

1 - 8 of 8 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1
I live in northern CA and commercial fish off of the beach in Kenai Alaska. I'm in need of what we call a "beach rig" for hauling totes of fish off the beach a mile or so and then over the road 5 - 10 miles to the processing plant.

A popular vehicle up there is a GM CUCV with flat bed due to its low gearing. Those however are getting hard to find.

I just traded here in CA for a 1984 K20 single cab with the 700R4 tranny and 4.10 gears. (Dana 44 front/Gm 14 bolt SF in rear).

While ground clearance is not an issue for the most part, traction on both wet/dry sand and "marbles" (small round 1 - 2" diameter rocks) is an issue while hauling up to 4000lbs on the flatbed.

I'm looking for input on tire size (width/height) and gear ratio. I'm thinking of beefing up the 700R4 but could be swayed towards a TH400 if the consensus was that it was better for my application. The CUCV's have the old school 37" Hummer tires on them and they do well in the sand but could be wider for the "marbles".

Would I be better off going with the Hummer tires and changing the gearing to 4.56 or 4.88's or sticking with the 4.10's and maybe a smaller diameter but wider tire?

Any thoughts on trans/gear ratio/tire size for this application? I won't put 1500 miles a year on this rig as fishing season is only 6 weeks long.

I can't post a link here to one of our videos since I don't have enough posts yet but if you look up "Alaska Commercial Salmon fishing 2010" on youtube, you'll see the beach conditions.

Thanks!
 

·
Premium Member
Joined
·
14,085 Posts
I would think airing down as low as you can and still be streetable with the military tires would be fine. Just run it in low range. I would also think the money would be better spent on a locker or limited slip then on gears.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #3
I would think airing down as low as you can and still be streetable with the military tires would be fine. Just run it in low range. I would also think the money would be better spent on a locker or limited slip then on gears.
Could I run the 37's with the 4.10 gear ratio? How about with the 700R4 trans? Wasn't sure if it wouldn't always be "hunting" for a gear. Not real familiar with the locker, what exactly does that do and how does it work?
 

·
blatant asshole
Joined
·
11,739 Posts
700r4 has a lower first gear than a 400 does. And its noticable. 4.10x700r4 = 4.56xth400 first gear.

What speed?
Road time?

Any thing done to the cucv as far as tires will work on the k20.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #5
700r4 has a lower first gear than a 400 does. And its noticable. 4.10x700r4 = 4.56xth400 first gear.

What speed?
Road time?

Any thing done to the cucv as far as tires will work on the k20.
Speed on the beach is slow, 5-10mph (just a mile at most), on the road, 55mph for 5 - 10 miles.
 

·
blatant asshole
Joined
·
11,739 Posts
So on road ruels out ag tires.

Either 37/38 mil tires on reg rims or find some of the xlm 38" and rim to fit (i think they are 16" but maybe 20")

Just run tcase low on the beach and let the trans do it thing
 

·
Premium Member
Joined
·
4,522 Posts
Not much room in tire capacity for airing down with 4k on the bed.

Those CUCVs probably have at least a gov-lock in back, your stock truck is open on both ends. Throw a lunchbox locker in both ends and I expect it to do very well. Just look for some wider tires, no need to go taller and force yourself to question gearing if ground clearance isn't an issue. Something in a 33x12.5 or so should exist and would leave you geared very close to stock, but give you the extra contact patch for the sand & marbles that will help you go over and not dig.


Not real familiar with the locker, what exactly does that do and how does it work?
There are several styles and types. The bottom line is a locked axle will put power to both tires so that you don't spin just one tire. If one tire loses traction, the other will continue to push you forward.


I'd put an Aussie in the front and see how it does. That'll be completely transparent on the road in 2 wheel drive, which is nice. If it needs more, throw a Detroit in the back. 33s will help the axle shafts live, too. 37s put a LOT more strain on everything.
 

·
Registered
Joined
·
1,615 Posts
Not much room in tire capacity for airing down with 4k on the bed.
Those CUCVs probably have at least a gov-lock in back, your stock truck is open on both ends. Throw a lunchbox locker in both ends and I expect it to do very well. Just look for some wider tires, no need to go taller and force yourself to question gearing if ground clearance isn't an issue. Something in a 33x12.5 or so should exist and would leave you geared very close to stock, but give you the extra contact patch for the sand & marbles that will help you go over and not dig.
If you can use 15" rims, it looks like there is a Super-Swamper that is a 35X15.50R15, it is good for 2800#/tire at 30PSI.
They also make a 33X15.50R15 that is good for a little over 2400# per tire.

Aaron Z
 
1 - 8 of 8 Posts
Top