Open rear diff. What a freakin' joke

[MikeR]

I honestly cannot see why anyone would want that POS open rear diff. The traction simply sucks!



In case some of you don't know it is kind of hilly around the Seattle area and it does tend to rain a 'lil bit. When I shopped for my wife's used 2wd, I saw quite a few trucks, and I couldn't remember all the features of each. To make a long story short, I ended up buying a 2wd truck with an open rear diff. I'm kicking myself for not double checking!



On the 15,17, and 18% hills here, of course this thing likes to light up the one rear wheel in the wet. There's one big particular 21% hill that drops me down from my neighborhood down to the mall, and I can't get back up it in this 5800 lb 2wd. My 7300 lb 4x4 (in 2wd of course) with the anti-spin diff drives right up it and any other steep wet hill without breaking any traction.



I realize 21% is very steep especially when it's wet, but the peg-leg is a joke when a 2500 lb heavier truck can climb it with ease. It makes me want to sell it!



If any of you new truck buyers are wondering... don't waste your time with the open diff!



-Mike

 

[WestTN]

open axle

You'ld be surprised what a couple hundred lbs added weight over the rear axle will do. And it is cheaper than trading.

 

[tcourse]

Which one

Would that be the one that drops down to southcenter mall at 180th? It's a bad one.

 

[Dr.Kayak]

My first truck was a $3,000 Dodge Ram 50. Long bed 2 wheel drive. It did the same thing. Lame. All my other trucks have had a limited slip rear end.

 

[Batman]

21% grade, holy steep grade!!!! I've had many cars that have had a hard time going up a 6%, I think if I were to have drive a grade like that my old car would've found a way to laugh at me

 

[Straight6Jeff]

Have you considered putting a Lock-Right in that open diff? I've put one in every peg-leg vehicle I have ever owned, and I have beat the snot out of every one without failure. The lock-Rights are a great alternative to a limited slip because: first, tehy actually work, and second, you would not have to have the rear set up. Just remove the side and spider gears, install new stuff and new (hardened) cross pin, and put cover back on. It took me an hour the first time I ever installed one.

 

[kchristopher]

How does one calculate grade %? I'm trying to picture a 21% grade by converting to degrees.

 

[MCummings]

It looks like this...



\

_\

__\

___\

____\

_____\

______\

_______\

________\



lol, Actually I don't really know how to convert it. but I have been on a 7% grade,, and I know 7% is steep. (atleast for 70MPH)



MerrickNJr

 

[Joseph Donnelly]

I have 4wd with open diffs and it has done well. If you are in situations where you need limited slip, I recommend the No-Spin or Detroit Locker. Aftermarket it is not so much more than installing a stock limited slip carrier and is much more effective. In my experience the stock limited slip diffs haven't worked well enough to be worth it in my driving situations. I go with the DL or open diffs. In ice and snow on side slopes with 4wd, the open diffs have an advantage because only one wheel slips at a time and the other holds the truck from sliding sideways off the cliff.



Type and condition of tires, and weight over the rear end make a big difference also.

 

[Mr. Brewski]

kchristopher - a 21% grade rises 21 feet per 100 feet of road. A 50% grade would be a 45 degree angle. The calculation for converting percet of grade to degrees would be 21% X 90 = 18. 9 degrees. I've seen the hill he's talking about and my open diff will smoke the inside rear without even trying.

 

[Thomas]

"a 21% grade rises 21 feet per 100 feet of road" — since percent of grade is the change in vertical location divided by the change in horizontal location ASSUMING NO CURVED ROAD (rise over run in your algebra class), a 21% grade actually rises 21 feet per 102. 1+ feet of road.



Again, using rise over run, a road that makes a 45 degree angle relative to horizontal is a 100% grade.



A road with a grade of 21% makes an angle of a bit less than 12 degrees relative to horizontal.



The percent of grade expressed as a decimal is the tangent of the angle of the road with respect to horizontal.

 

[Mr. Brewski]

I guess I should've mentioned 21 feet of rise (Y) for every 100 feet of horizonal (X) distance. Thomas your absolutely correct.



The correct number of degrees would be the ArcCosine of 21/100. (If my 20+ YO memory of trig is correct... ) 11. 86 degrees.

 

[Thomas]

Too many years teaching algebra for me.

 

[SlyBones]

hmmm... .



12 degrees. So where do I go wrong. I sit here at my desk, take a ruler and make it go up 12 degrees. Look at the angle and think nothing of it. -- Then go look at Mike's hill and think holy steep grade, batman. What gives ( other than my eyesight ).

 

[Batman]

I sit here at my desk, take a ruler and make it go up 12 degrees. Look at the angle and think nothing of it. -- Then go look at Mike's hill and think holy steep grade, batman.

hmmm... ... . that's what I said

 

[SlyBones]

yeah I know, I liked it.

 

[PRout]

What Joe said...



Peg leg diffs are usually safer. They suck for real 4x'ing though.

 

[Lsfarm]

Open differential

I agree that this truck is almost dangerous with an open Diff. When the pavement is wet, it is a consideration before pulling out in traffic.



With this much torque available, I think that the LSD should be part of the cummins engine package.



I feel for anyone without LSD. It wasn't available when I ordered my truck with 3. 54 ratio. I had to add it later. It sure made the truck nicer to drive.



Greg L

 

[PRout]

It beats gettin sideways w/ a posi.



I know of quite a few street-racers that lost it in the rain w/ wide tires (that hydroplane) & locked rears and ended the existance of their pride mopar possesions.

 

[John]

Mike, I know exactly what hill you were referring to! That one is absolutely deadly when it snows..... literally!