Wife drove in 4L for 20 Miles at 60 miles per hour.

[rickinAZ]

Doesn't the JL have a dash warning light/chime when your starting to go a certain speed in 4l

I don't know, but if the high rpms (for 20 miles!) don't catch your attention, not sure that a dash warning would.

Sponsored

 

[Bruce Willys]

What’s amazing is the lack of reading skills people have on here. Post #13 by Left Field has him calculating out roughly 4k RPM at 60mph in 4L due to the 2.72:1 low range, stock 3.45 gears and 8spd auto.

So, she didn’t “redline” it, she didn’t overheat the motor or t-case, she didn’t “kill the hubs”, she most likely did ZERO damage to the Jeep.

Why does Jeep not recommend exceeding 25 mph in 4L?

 

[Vinman]

Why does Jeep not recommend exceeding 25 mph in 4L?

Due to the excessive speed the internal components of the transfer case will endure.

 

[Vinman]

Engines will endure some serious abuse.
Old story that happened to me in the 80’s..
The company I worked for had an 87 or 88 one ton cube van with a 350 engine. The boss decided he wanted to get rid of the clutch fan and go mechanical (one less thing to go wrong, right?) and I was given the task to swap it out.
I picked up a flex fan at the local performance shop and did the swap, fired it up to ensure it ran properly and since it was the emd of the day shut it down and left for the day.
First thing the next morning the service manager and a tech hopped in it and went on their way, fifteen minutes after they I get a call from the manager and he asked what I did to it as it would only go 60 MPH. Me being the smartass I am I responded “well, thats the speed limit”

Fast forward an hour or so and he calls back and says “come get this van, the grill melted” I’m like WTF? But took another guy and go retrieve it.
By the time we got to it, the truck had cooled off and we head out, it took less than 5 minutes to peg the temp gauge.
It didn’t take long for us to figure out the fan was pushing air instead of pulling due to me getting a fan for a different rotation water-pump.

We ended up completely removing the fan and made it almost back to the shop before traffic slowdown caused it the start running hot again so we had it towed the last bit.
Bottom line was that truck was driven for a full hour with the throttle hard against the floor and at the end of the day, no damage done to the motor.
I left that job a year or two later and that truck was still running great and didn’t even use oil between changes.

The best part of that whole ordeal was when we got back to the shop and the owners were waiting for us in the parking lot (shop was now closed) I got out of the tow truck and before they could say a word I said “you can do whatever you want to me for getting the wrong fan but it wasn’t me that drove it for an hour with my foot on the floor board with the temp gauged pegged” the boss’s response was “good point” and he turned around and walked away. The service manger caught hell the next day.

 

[jeepdabest]

My wife did the same thing. Hurt the brand new roof rack.

 

[Bruce Willys]

Due to the excessive speed the internal components of the transfer case will endure.

I know, I was asking the person who claimed driving 60 mph in 4L 'probably causes no damage' why they thought that.

 

[halsjeep]

I would say that is definitely a problem. I would trade her in as soon as possible, and I don't mean the Jeep.

 

[Zandcwhite]

I know, I was asking the person who claimed driving 60 mph in 4L 'probably causes no damage' why they thought that.

The same reason we run 37×12.50's on stock rims, have been known to lock our rear difs and drift in 2wd, disconnect our sway bars and run wide open in the desert. There's a lot of things the manual and the internet will tell you you can't do, most of the time it's more about bean counters and safety regulations. People can't drive so they dumb it all down. You'll never know where the limit is unless you find it every once in awhile. It's virtually the same transfer case that was in everything from xj's to yj's for the last 30+ years and I've personally beat them much harder than cruising down the freeway at 60 and have yet to break one. If it's about the rpms, why do they have the same mph limit for rubicon 4-1 t-cases?

 

[neil]

The better question is does she understand how to use 4wd now?

 

[Oldbear]

I’m still trying to figure out how she turned

 

[roaniecowpony]

The engine is trashed. The only fix is a 6.4 Hemi. Let this be a very expensive lesson to her.

 

[RV Wrench]

How is this possible?

Even with a Tazer, the JL has a factory speed limiter of 30mph in Low range, regardless of engine RPM.

 

[Boogey]

How is this possible?

Even with a Tazer, the JL has a factory speed limiter of 30mph in Low range, regardless of engine RPM.

I have never heard that before. Have you ever actually tested this or been in this situation?I know the tech specs might say things but that would be soemthing! I am tempted to try it!

 

[_olllllllo_]

Crawl ratio has 0 to do with it. Your 6th gear ratio in a manual is .72, the autos are .67. A stock Sahara tire has a diameter of 8.3 feet (pi times diameter/12). That is 636 revolutions per mile. 60 mph is equal to 1 mile per minute, so you would need 636 rpm at the tire to travel 60 mph. In an auto you would be turning 3,999 rpm at 60mph (636x 3.45 axle ratio x 2.72 t-case ratio x .67 8th gear ratio), in a manual you’d be turning 4,237 rpm due to the slightly higher 6th gear ratio. No this isn’t redline, no this isn’t anywhere near the rev limiter. Definitely higher rpm than you want to cruise around at, but not anywhere near high enough to cause damage.

Excellent explanation. Learn something new everyday. I found a gear calculation website, but didn't have the 2.72 t-case ratio. Thanks for the thorough breakdown.

 

[Dagwood]

I hope your next wife is a jeep girl

Sponsored