How to Narrow an 8 3/4 Rear End

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jtkaaa07

jtkaaa07

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8 3/4 Narrowing how to

I am in the process of putting a mini tub kit, spring relocation, and axle shortening in my 69 dart, and thought I would share pic's and a how to on the shortening of a housing. As with most housing's this one was bent right from the factory, this rear end came out of a C body.

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Rear end measuring tool, is a must have for this job, bought on Ebay for $25

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Bought a junk 741 bare housing to use with jig

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Put the cent plug's from my jig in the carrier, and tightened up caps, then check to make sure it moves freely side to side

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I cut the old ends off the housing, and cleaned them up in the lathe, make sure to have a nice taper on end to get good weld penitration, you can also buy these brand new if you don't have access to a lathe, Dr Diff, and a few other vendors have them in billet steel as well

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Make sure to taper housing ends too

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Cut housing to desired length, I made mine 48", with 36" perch centers, this is where the rear end ruler is really handy.

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Time to straighten bent housing, I have 2 1/2" inch plugs that fit in the inside of axle tube


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Plug on one side with threaded rod end

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In the jig, chained to table, then heat on the side in the direction you want to bend it, apply pressure from jack until lug slides in smoothly, then let cool completely before removing anything

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The threaded plug in my kit has a notch cut in it this is how you clock the end's, they can be off a little without any problems with E brake or anything else

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All finished and ready to go back in, now it's time to shorten the Moser axles, I send those in to machine shop, and have them cut, splined , and re hardened

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Forgot to note, never remove any of the jig until the housing cool's on it's own, do not use water, or wet rag to cool it down or it will twist all over on you, trust me I've been there!! after it completely cool's off the plug's should slide out without much interference at all. I know there will be many here that would say just ship it to Moser, and I would have to agree in most cases, but a good friend of mine has been doing these for many year's and he set me up with the jig. I'm the type of person that has to try and do everything on my own, so hopefully this will help anyone wanting to try it.

Almost time to get some tire under this beast, soon!!

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Hey guy's, I thought I would post some pic's of the progress, spring relocation kit is in, axles are on there way to Moser, and brakes are rebuilt! Next step is Mini tub, hopefully that will be done this weekend or early next week.

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I took 5" off the stock length of an A body rearend, and just so I don't get hung on the cross, no factory A body housing was used in this project, that's up on a shelf just in cast this doesn't work LOL! I think I'm going to set the axle back an inch from stock, my tires were really close to the front of quarters before, and the nice thing with doing this is, you can adjust up, down, forward or back by just moving to another hole.

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jtkaaa07 said:
I am in the process of putting a mini tub kit, spring relocation, and axle shortening in my 69 dart, and thought I would share pic's and a how to on the shortening of a housing. As with most housing's this one was bent right from the factory, this rear end came out of a C body.
View attachment 1714847671
Rear end measuring tool, is a must have for this job, bought on Ebay for $25
View attachment 1714847672
Bought a junk 741 bare housing to use with jig
View attachment 1714847673
Put the cent plug's from my jig in the carrier, and tightened up caps, then check to make sure it moves freely side to side
View attachment 1714847674
I cut the old ends off the housing, and cleaned them up in the lathe, make sure to have a nice taper on end to get good weld penitration
Click to expand...



How do you get the "clock rotation" correct on the end pieces in your last pic??

Treblig
 
Awesome thread, This should be a Sticky. I wish I lived near you I would have you shorten a 8 3/4 for me.
 
Thank's, there not that hard to do, and you can by the jig's on Ebay for around $100, the only ones I made were the ones that go inside the tubes to straighten the housing.
 
Nice work.

I did one in the garage with another Fabo member a while back. Takes some time, but, if you have the tools it's not that hard to accomplish.
 
Nice work.

I bought the tools to do this myself. Was hoping to already have started but another project has held me up.
 
Thank's for the comments guy's, yeah I was going to send it out, but by the time I paid shipping, I'd have $250 into it! A buddy of mine had the jig's, and said that with all the other stuff I can do it would be easy, and actually it was pretty easy. Like I said I hope it help's other's on here try and do it themselves. Next will be setting some new gears, I'm pretty luck to have some really good older friends that have been doing this stuff for years, they can save you a lot of headaches LOL!
 
fishy68 said:
Nice work.

I bought the tools to do this myself. Was hoping to already have started but another project has held me up.
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Yeah, I hear that, I've been talking about doing this for a couple years, this fall I said no more excuses and just started tearing it apart. When you get to doing your's if you run in to any problem's shoot me a message, I can try to help

Jeff
 
I like your method of straightening it. I put one together for my car and danged if it didn't look swept back on the tubes. I got it straight kinda using the same method you did.

I am in the process of doing up an A rear with a back brace right now. Then I have another one to do at some point.


8-3-4-build-jpg.1714847796

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Once done I will set it up with a suregrip and 4.56's. :D
 
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Can you straighten a housing after welding on a backbrace? I'm guessing that if someone was going to narrow, back brace, and move the spring perches, the last thing that was done would be to weld the housing ends on?
 
lucky13 said:
Can you straighten a housing after welding on a backbrace? I'm guessing that if someone was going to narrow, back brace, and move the spring perches, the last thing that was done would be to weld the housing ends on?
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Sure you can, but, if I were doing a back brace, I'd check the housing for straight, then chain it down to prevent movement. Also, I'd only do little patches and let it cool, just like Bad Sport is doing, look's great bye the way!
 
You'd be surprised how bent a housing can be before it causes accelerated wear. I've also straightened housings by heating one area , then cooing it by dabbing a damp cloth on it. This shrinks the metal slightly and pulls the tube one way. Not for the faint hearted :)
 
jtkaaa07 said:
Yeah, I hear that, I've been talking about doing this for a couple years, this fall I said no more excuses and just started tearing it apart. When you get to doing your's if you run in to any problem's shoot me a message, I can try to help

Jeff
Click to expand...

Will keep that in mind Jeff. Thanks, Tracy
 
jtkaaa07 said:
Thank's for the comments guy's, yeah I was going to send it out, but by the time I paid shipping, I'd have $250 into it! A buddy of mine had the jig's, and said that with all the other stuff I can do it would be easy, and actually it was pretty easy. Like I said I hope it help's other's on here try and do it themselves. Next will be setting some new gears, I'm pretty luck to have some really good older friends that have been doing this stuff for years, they can save you a lot of headaches LOL!
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what company were you going to send it out to?
 
That ruler really does make life easy. You can get the ruler or a whole narrowing kit from Leadmine Product, 198 State Road YY, Tunas, MO 65764 Tel: 417 733 1012 (They had a website but it is down for some reason)

I used to narrow without the ruler by making wooden gauges so really appreciate using the ruler and a tape measure.
 
straightlinespeed said:
I cant wait to see the car this next year. Do you have any long road trips planned like the one we talked about?
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No, not yet, the motor is getting pretty tired lol! I did buy a really nice 72 340 this spring, pretty fresh, but spun bearing, i'm debating on going with a stroker in it, but money will be tight after all this crap is done. I guess I'll have to sell more of my stash of goodies:D
 
jtkaaa07 said:
No, not yet, the motor is getting pretty tired lol! I did buy a really nice 72 340 this spring, pretty fresh, but spun bearing, i'm debating on going with a stroker in it, but money will be tight after all this crap is done. I guess I'll have to sell more of my stash of goodies:D
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I totally understand that. I'll be doing the whole engine thing soon as well.

Keep the pics and progress coming!
 
grimreaper said:
That ruler really does make life easy. You can get the ruler or a whole narrowing kit from Leadmine Product, 198 State Road YY, Tunas, MO 65764 Tel: 417 733 1012 (They had a website but it is down for some reason)

I used to narrow without the ruler by making wooden gauges so really appreciate using the ruler and a tape measure.
Click to expand...

That's where I bought my ruler and plugs from. Nice pieces. Got the bar from Speedy metals. All total the price was less that it was going to cost to have one narrowed plus I don't have to haul it back and forth twice at 100 miles per round trip and I will have the jig to do future rearends
 
What are you guys using for the bar?

I bought the plug kit as well, but haven't sourced the bar to complete the jig yet.
 
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