4wd Low behavior

[bejor77]

Hi there!

I'm new here, I've had other 4x4s on the past, but I'm new to the Jeep brand.

Yesterday I took my brand new KK (4x4 ltd automatic transmission) to the mountain, very steep climbs and everything went fine going up, but on the way down it made me nervous since there are long descents that do not require the HDC but my KK didn't hold up very well on 4wd Low and 1st, at first it tried to hold but after 2000 rpm it let the RPMs go up to 5000 and the speed around 15 mph and I had to use the brakes very often making them overheat a bit

In the past I've had other 4x4s and on the same descent they used to hold up very well on 4wd Low and 1st, automatic or manual transmissions. I'd like to know if this is normal or I have to take it to the dealer to check it out.

Thanks guys for your help.

Cheers,

Erick

 

[ridenby]

Sounds as if you should of kept RPM/speed a little lower

 

[bejor77]

Sounds as if you should of kept RPM/speed a little lower

Yes, but how? the engine/transmission/transfer are not holding it, as I'm used to when I had my previous 4x4s, it gained speed faster than I wished for. Even a 2009 Ford Explorer was doing better than me as the guy didn't need to use the brakes half the times I did.

 

[tjkj2002]

Yeah the reality of having a high 1st gear in the 42RLE trans and a not so low range of 2.72:1.The 42RLE ***** for any type of compression braking with it's high 1st gear.

 

[HoosierJeeper]

Mine will hold at 5 MPH in 4LO/1st gear going down hill, I don't do anything but steer...

 

[yellocoyote]

Depends on the pitch of the decline too... I've been in places where it will hold steady at 5 or 10 mph, and in other places around 20 mph.

 

[bejor77]

Depends on the pitch of the decline too... I've been in places where it will hold steady at 5 or 10 mph, and in other places around 20 mph.

Thanks for the info, so it's normal for you on a very steep hill descent to get 5000 rpm and 20 mph?.

Also, have you used HDC for descending on long periods of time? or will it also get the brakes to fade?

 

[HoosierJeeper]

Actually, our KJ's don't have it, but my LR3 does, and they way it works is through the brakes, because I can feel the "grinding" of the ABS system....I thought the KK's used engine compression...

 

[yellocoyote]

Thanks for the info, so it's normal for you on a very steep hill descent to get 5000 rpm and 20 mph?

It's normal to go faster the steeper the descent, yes. I don't know that I'd be comfortable letting it get up to 5000rmps though... I try not to let mine get too much above 3500rmps in that kind of situation. :-s

 

[tjkj2002]

Thanks for the info, so it's normal for you on a very steep hill descent to get 5000 rpm and 20 mph?.

Also, have you used HDC for descending on long periods of time? or will it also get the brakes to fade?

HDC will heat your brakes up fast and you will get brake fade and the HDC will not work very well.

Lower gear ratio's help with going down steep hills.With my current setup with 4:3:1 low in the t-case on moderatly steep downhills I have to give it gas to keep going otherwise my KJ stops on it's own without brakes being touched(Have a KJ no HDC).On very steep downhills I can keep it under 2mph very easily with a slight tap on the brakes,keeps the engine rpm's well under 1000rpm's.

 

[Phil + Neela]

Thanks for the info, so it's normal for you on a very steep hill descent to get 5000 rpm and 20 mph?.

Also, have you used HDC for descending on long periods of time? or will it also get the brakes to fade?

As said above, HDC will also cause brake fade. It works through the pulse system of your ABS--the only difference is that it can work individual wheels to control the stability of the vehicle as well and keep it going in a straight line...to a point.

As for hills, I discovered something strange with my KK. If I let it creep along (no skinny petal) and start with the RPMs around 1000, it won't roll much higher and steadily let me down the hill. But, if I start down a hill over 1500, the RPMs will climb until I'm tapping the brake to slow my descent. It works most of the time, but the hills aren't super steep where I've tried it so far...:shrug:

 

[bejor77]

As said above, HDC will also cause brake fade. It works through the pulse system of your ABS--the only difference is that it can work individual wheels to control the stability of the vehicle as well and keep it going in a straight line...to a point.

As for hills, I discovered something strange with my KK. If I let it creep along (no skinny petal) and start with the RPMs around 1000, it won't roll much higher and steadily let me down the hill. But, if I start down a hill over 1500, the RPMs will climb until I'm tapping the brake to slow my descent. It works most of the time, but the hills aren't super steep where I've tried it so far...:shrug:

I did noticed that it will hold if you start at 1000rpm but just for a few moments, then it will let go downhill :disgust:

 

[J-Thompson]

Many factors cause this
Things like gearing
engine compression
electronics in the trans not keeping it in the right gear
electronic "baby sitters"

I would also be concerned about brakes that
"fade" that easily
I have gone down some crazy long steep hills
When Telico was open in my TJ and brake fade
was not an issue and I have a lot less brake than
a KK and weigh with in a few hundred pounds

Look up on how to slow a comercial truck on a steep
grade
You use engine braking as well as brakes
Slow it down then let it speed up and repeat
Friction builds heat
Brakes only cause friction if you ride them

Then again I like to go down hills with instructions like
"ok DO NOT use your brakes or you will probably roll
just put it in 4wd low and first gear and let it roll then
slam on your brakes when he yells at you to"

 

[bejor77]

Many factors cause this
Things like gearing
engine compression
electronics in the trans not keeping it in the right gear
electronic "baby sitters"

I would also be concerned about brakes that
"fade" that easily
I have gone down some crazy long steep hills
When Telico was open in my TJ and brake fade
was not an issue and I have a lot less brake than
a KK and weigh with in a few hundred pounds

Look up on how to slow a comercial truck on a steep
grade
You use engine braking as well as brakes
Slow it down then let it speed up and repeat
Friction builds heat
Brakes only cause friction if you ride them

Then again I like to go down hills with instructions like
"ok DO NOT use your brakes or you will probably roll
just put it in 4wd low and first gear and let it roll then
slam on your brakes when he yells at you to"

I'm used to do it the way that you do and try not to ride the brakes, but my KK gained speed so fast that I didn't feel safe and the engine whining at 5000 RPM is not fun :freak3:

It will have the first dealer service en January 18th, I'll make them check everything.