Potential drive train issues when upgrading to 35"/37" tires?

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redcheetah

redcheetah

10 Year 15 Year
Joined
Feb 27, 2006
Threads
37
Messages
310
Location
riverside, ca
I have a 1981 Toy 4x4, longbed , 22R, W/4.88s in the axles, lockers, Marlin dual case setup (4.70). It is currently on 33” tires and I am looking to upgrading to 35s or 37s. I wheel fairly tame trails (John Bull in Big Bear, CA for example), do not hammer my rigs, and will take the bypass if necessary (I have no pride). I am curious what parts have proven to be the weak points in the drivetrain when you move up to the 35”/37” range? I was looking into the Marlin Marfields to add a bit of strength in the front and Marlins chromoly rear axles for the rear. Will this be sufficient for the type of wheeling I do or do I need to step up to more major mods?

I searched and found breakage threads but they usually dont state the type of wheeling or their driving style so I was wondering if there is a consensus on what upgrades you need to step up in tire size - Thanks
 
Not the best pic but here is the rig in question
Truckhaven 012.webp
 
I am running 35" bfg mts and have not had any trouble, 5.29s front and rear with a Detroit in the rear and warn hubs up front, I wheel a lot of rocky trails and do a bit of crawling and have not had any problems.
 
Thanks for the info. I found a guy locally that has a complete '85 front axle (housing, longfields, high steer, etc) with numerous upgrades that he is willing to sell for a reasonable price. It would take care of most of my upgrade issues. Are the 81' and 85' axles interchangeable?
 
Longfields are a MUST.

The parts you are getting will do fine, the hi-steer will be nice too.

The rear axles and hub gears will be fine. You will have problems with ring and pinion before you have troubles with those.
 
Thanks for the info guys. I picked up that other axle today. It had among other things - All Pro inner shafts, Longfields, High Steer setup. This will be a good start for me. I still need a few parts like the IFS steering box and the mounting kit. I also need to figure out how to put it all together.
 
Toyota Front Axle Rebuild

its easy! once you get good at it you will be able to do a tear down/put together in 20-30 min, on the trail :D
 
I started popping birfields left and right as soon as I went from 35's to 37's. Longs are the only way to go.
 
x2......look into posibly up grade to Longfields as was already said.

If you dont just be carful when wheeling in reverse. Because you are locked up front ( I assume) that is where the real damage comes into play. If you dont turn the wheel all the way in one direction and hammer the skinny pedal you should be fine on 35's.
KLF said:
A lot of breakage problems are caused by the loose nut behind the wheel with the heavy foot.
Click to expand...
 
birfields

Upgraded birfield joints are a must, we offer joints that can use your stock inners for the budget concious, or a full kit that upgrades the inner shafts as well. Also the diffs should be setup with the Later type HD ring & pinions. We only use these by Nitro Gear. The pinion head is thicker than the typical 85 & older (aka 4cyl) design that most sell. Also use solid preload spacers, and make sure to have plenty of carrier bearing preload.
 
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