40s on a 30
(and why it's a bad idea 😂)
We’ve all seen it, “You can’t run a big tire on a Dana 30” on every forum and Facebook group imaginable.
However, with the advancements of technology and strength in the JL Advantek series axles, I decided to test the limits and see what I could get away with.
Now, 40s were not the original plan. I wanted to stick to 37s with the m186 and m210 (also called Dana 30 and 44) axles on the sport JL as I felt that was a safe setup. But after 40s were delivered instead of 37s, I decided to push my luck instead.
For over two months, I drove every day on this combination with 100% stock axles and never had an issue. Even the power on road was still ok with the 2.0 turbo.
It wasn’t until I brought the Revelator to Johnson valley that things changed rather quickly.
After watching Jeff in grapplerjk climb up a canyon with ease, I decided to try to do the same.
Bob Corcoran (theunofficialbob) spotted me through the first few sections of rock where it was immediately noticeable that lockers would be needed to continue. I pushed forward and ended up high centered on a boulder I could not get around and we decided that this was the end of the line for the little JL that could(‘nt).
After backing down a few ledges, I found myself stuck again. Rocking in every direction without any real movement was getting frustrating and at some point I hit the gas a little too hard and heard the all too familiar sound of disappointment.
The spider gear broke and eventually exploded, ruining the ring and pinion gears.
Luckily the JL has a front axle disconnect which allowed me to run in 2wd without spinning the ring and pinion gears and causing more damage.
Here is what it looked like when Off-Road Mafia opened the front diff:
And here is the trophy that Off Road Mafia made from my carnage!
So this goes without saying, don’t do this! There are definitely limits and I plan to drop down to 37s pretty soon so this doesn’t happen again!
Want to run bigger tires? Check out these axles instead:
- JL Rubicon 44s front and rear
- Freedom fabworks superduty/14 bolt
- Dana Ultimate 60
- Dynatrac pro rock series
- Fusion 4x4
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