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Replacement rear axle question

Randyzzz

Randyzzz

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After much consideration I have decided to go with a 9” rear axle on Red. I have a question on width that I can’t seem to find good info on. I know the stock WT front is 56” wide, and the rear is 54.5” wide. Why wouldn’t you want the same track front and rear? I know that supposedly a narrower rear gives a better turning radius, but that didn’t seem to make a difference in Copper ( both axles same width) plus in the snow it seems to track better following the front ruts instead of the rear bouncing left to right following one of the other ruts. The reason I’m asking is getting a housing narrowed locally costs more than a fabricated housing from Speedway. But Speedway has either 54” or 56”. I’m leaning towards 56”. Your thoughts?
 
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FWIW, I've read a narrower rear is supposed to help stability when driving at speed. Not sure it makes any sense, but that's the gist of it.
 
Spieg said:
FWIW, I've read a narrower rear is supposed to help stability when driving at speed. Not sure it makes any sense, but that's the gist of it.
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Well, with a 6.0 I’ll need all the stability I can get?
 
I am only guessing, but when turning your inside rear wheel would be outside the front tire track if they are the same width. If the rear is narrower it might track the same as the inside front tire.

I need to measure track width on my truck and SUV to see what modern vehicles do.
 
Been doing a lot of studying while my back is recovering. Learning lots of stuff I never thought of. Seems in the race/drift world, the common thought is a narrower rear causes oversteer and a wider rear causes understeer. There’s a lot to do with distribution of weight too.
 
Randy a very interesting subject. I've read some different articles about the the different widths. So are you going with a shell or fully built 9" ?
 
Long time ago I was told/read it had to do with tracking down going down the road. Something about grooves or crowns in the road:shrug:
My last truck which was not a dually had a factory wider rear axle than the front so much so that it had wider bedsides than the standard model. It road and handled great.
I don't forsee the wider rear being a problem but I am far from an engineer.
 
Belizeit said:
Randy a very interesting subject. I've read some different articles about the the different widths. So are you going with a shell or fully built 9" ?
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Hard to say at this point. I already have a 9” third member with correct gearing, not anything special but it’s a start and would provide a good base to see if I’m happy with 3.54 gears. I’m thinking about buying a housing and building it from there. Speedway has some nice looking fabricated bare housings for $399 and free shipping. Although thIs 9” full floater kit seems like a bargain at $975.
http://www.9inchfloater.com/CompleteRrEnd/CmplteRrEnd_28_31.htm
 
Barrys- did you have one of the rear steer GM’s? It had a wider rear end- looked unique to say the least.

The more I research it, the lighter Scrambler rear end sounds like a prime candidate for oversteer in stock form. I’m thinking trying to get as “square” as possible might be the best bet.

I had always thought widetrack axles were 56” front and 54.5” rear. Now the measurements I’m finding are 55.5 rear. I guess I could pull the wheels off mine and see... I believe the later YJ and up are more “square” so that might be Jeeps attempt at better stability.
 
Yes, I have a Silverado Quadrasteer than had the same turning radius as a grand cherokee from the same year. It was totaled last month but I bought it back.
 
barrys said:
Yes, I have a Silverado Quadrasteer than had the same turning radius as a grand cherokee from the same year. It was totaled last month but I bought it back.
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I have driven those. They handle great! I never really felt that comfortable with having a computer control my steering- but that’s just me. I guess working in the dealership world exposes you to all the possible failures. Are you going to fix it or use the powertrain for a swap?
 
Keep in mind that having rear steer can correct for various issues the axle setup could have without it. Just saying it is not apples to apples comparing a rear axle wider than front with rear steering to any type of setup without. You can also program in phase steering at higher speeds (stability) and out of phase steering at low speed (turning radius reduction). That can have huge improvements for all situations.

For those vehicles with rear steering, the rear axle is wider for the simple need for extra clearance between tires and body/frame.
 
ag4ever said:
Keep in mind that having rear steer can correct for various issues the axle setup could have without it. Just saying it is not apples to apples comparing a rear axle wider than front with rear steering to any type of setup without. You can also program in phase steering at higher speeds (stability) and out of phase steering at low speed (turning radius reduction). That can have huge improvements for all situations.

For those vehicles with rear steering, the rear axle is wider for the simple need for extra clearance between tires and body/frame.
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Well put. I remember doing training on those when I worked for GM. There was a lot going on between the rear axle and the computer. Different reactions for different vehicle speeds and steering input angles and speeds.

Thanks for all the input. I’ve decided to keep it square and go with a 56” rear width.
 
Randyzzz said:
Are you going to fix it or use the powertrain for a swap?
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If I can find the same color parts used soon, I may fix it and sell it. Probably will part it out as it was damn near mint condition. Toying with the idea of putting the engune/tranny in my 8 but would probably make more sense to sell it and buy fuel injection for the 401.
 
barrys said:
If I can find the same color parts used soon, I may fix it and sell it. Probably will part it out as it was damn near mint condition. Toying with the idea of putting the engune/tranny in my 8 but would probably make more sense to sell it and buy fuel injection for the 401.
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Would make a heck of a swap. But probably wiser to inject what’s already installed.
 
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