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Narrowing a Mopar 8.75" axle
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Author:  Dart270 [ Fri Apr 27, 2018 12:59 pm ]
Post subject:  Narrowing a Mopar 8.75" axle
Slant 6 Sages,

I am thinking about narrowing my 8.75" rear in the 68 Dart about 1" per side so I can fit wider rims and tires. I just installed the Streetlynx suspension from Reilly Motorsports and I am fixin' to minitub the car.

I have green bearings and aftermarket axles with plenty of spline length. I figure I can cut the axles down to the desired length and dress the ends/splines smooth.

Do you think I can just cut the ends of the housing off and weld on new housing ends from Dr. Diff without a jig or any fancy alignment equipment?

http://www.doctordiff.com/billet-steel- ... -ends.html

I figure I would do the following:
1) Cut the housing ends off and deburr and clean up the tubes
2) Slip the new housing ends over the shortened tubes and bolt the shortened axles onto them to align the axes of the new housing ends with the axles, and
3) Weld the new ends on using an alternating pattern to minimize heat warpage/distortion.

Any thoughts on this procedure?

Thanks much,

Lou
Author:  Badvert65 [ Fri Apr 27, 2018 1:28 pm ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
A friend of my bought a jig to narrow housings. He said it is nearly impossible to correctly align things for welding without the jig.
I'm jus' sayin'
-Matt
Author:  sandy in BC [ Fri Apr 27, 2018 1:58 pm ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
My 8.8 was done in a driveline lathe. The lathe is the jig....the ends were welded in the lathe. That's stock ends in tube....tube butt welds.

Dr Diff ends are made to press/slip into the axle tube and should line up fine.

I would cut the tubes....dress the tube ends by hand ....slip/press in the Dr Diff ends....install everything(axles etc) and see how it rolls when turned by hand. If good...dismantle .....tack weld...reassemble and check....welder up.

1" with the right offset wheels can give 2" clearance.

1 1/4" per side on the Desoto allowed me to easily install 265/75/15 tires, Before that 235/75/15 was the max.
Author:  Dart270 [ Sat Apr 28, 2018 3:58 am ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
Thanks for the thoughts, guys. I like the 2-assembly/check process, Sandy.

I'll be interested to hear others chime in, and I'll likely have a conversation with Cass (Dr. Diff) about this too.

Lou
Author:  sandy in BC [ Sat Apr 28, 2018 12:28 pm ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
That seems to be a narrowed rear for about $100 if you do the welding.

Will you cut and dress the axles by hand?
(2 hours per axle)

or?

How are you cutting the housing?
(2 cuts per side?) ....or ( one really accurate cut per side?)
1 cut by hand 1 hour

The machine shop that did my 8.8 cut the end off in a cutoff saw....then did the measure cut in the lathe.

Zip Cut is fast and pyrotechnic but requires a lot of cleanup work.

Machinist grade hacksaw blades and a large collection of hand files would be my choice.
Author:  Dart270 [ Sun Apr 29, 2018 4:04 am ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
Yes, I would cut all this myself. I have a 10" miter saw and I can use a metal blade. I also have a large belt sander now with a 90 deg table. I decided to buy a sander that would last me a LONG time (hopefully). It has a table and belt big enough to face an int or exh manifold flange and a table about the size of a Slant cyl head that tilts 0 - 90 deg. I use it a LOT.

Lou
Author:  Greg Ondayko [ Sun Apr 29, 2018 5:57 am ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
You would have to devise some method of getting bearing housings on the end square and centered with the carrier bearings.

Also when welding warping tends to occur. If dr diff has a kit that are sleeved in ends for such a project then i would use it.

Also considering that the brakes and bearings are attached to what you are welding i would say everything needs to skookum as frig.


Greg
Author:  Badvert65 [ Sun Apr 29, 2018 6:56 am ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
My buddy has a jig and from the 8 3/4's he has done, he says none of them have been straight or square to begin with. This is likely due to age, I would think.
Author:  slantzilla [ Mon Apr 30, 2018 10:54 am ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
Quote:
My buddy has a jig and from the 8 3/4's he has done, he says none of them have been straight or square to begin with. This is likely due to age, I would think.
When I worked at the hot rod shop we did a lot of 8.8 Ford housings and none of them were ever square to start with. 50 year old Mopar housings will probably not be any better.

Mittler Brothers makes a very good mock up jig, but it is spendy.

The big thing when doing it like Sandy describes is to have good reference points before you start cutting, and measure 3 times, cut once.

If you really want to get a good tire under it a mini tub is in your future. :mrgreen:
Author:  Rob Simmons [ Mon Apr 30, 2018 11:13 am ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
My Lemons partner just bought a cool rod with screw on ends designed to keep your housing ends square. He used to work at a chassis fab shop. First job is to put 9" ends on his Mustang's 8.8. Other projects to follow... :twisted:

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Author:  sandy in BC [ Mon Apr 30, 2018 11:14 am ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
Some of the reasons I like using hand tools on a job like this are:
The amount of think-time you get.
As soon as you are off the cut line you can correct.
Very thin cutlines.
You just never cut/file more than you have to.

A lot of GMC 14 bolt axles I have seen over the years had Camber opposite to load.
A full floater axle makes that work
I always thought that and a tinny bit of toe-in would make sense. That's how trailer axles start out.
Author:  Rick Covalt [ Mon Apr 30, 2018 5:09 pm ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
Quote:
If dr diff has a kit that are sleeved in ends
If you have ends that are sleeved I don't see why you can't just cut the housing and axles off and bolt the axles to the ends and slide them over the housing and into the axle bearings. Everything should be in place because the axle is bolted to the end, right? If so then put 4 heavy tacks on it on each new housing end, and then disassemble and weld alternating back and forth from side to side, and top to bottom, to keep the end from pulling to far from the heat. I think you can do it!! :D :D
Author:  Tim Keith [ Mon Apr 30, 2018 6:51 pm ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
Some cut the axle tube along the line from a worm drive host clamp.
Author:  Dart270 [ Tue May 01, 2018 4:03 am ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
Thanks everybody. This is great.

Lou
Author:  Old6rodder [ Tue May 01, 2018 9:47 am ]
Post subject:  Re: Narrowing a Mopar 8.75" axle
Quote:
Quote:
If dr diff has a kit that are sleeved in ends
If you have ends that are sleeved I don't see why you can't just cut the housing and axles off and bolt the axles to the ends and slide them over the housing and into the axle bearings. Everything should be in place because the axle is bolted to the end, right? If so then put 4 heavy tacks on it on each new housing end, and then disassemble and weld alternating back and forth from side to side, and top to bottom, to keep the end from pulling to far from the heat. I think you can do it!! :D :D
Been doing it this way forever (or so it feels :lol: ). Works with non-sleeved as well, just tack or strap on some splints.

Latest one was offsetting an old Ford 8" for the 'Brick. Removed a chunk of housing from one side, and installed it in the other side. Then just swapped the short & long axles.
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