I've been looking through the tech articles and haven't been able to find much on narrowing a 9" rearend, or any, for that matter. I was curious what a jig for such an operation looks like/consists of and how the process is carried out. Anyone have any info they might be able to offer up? Thanks in advance! Casey
I've never done it....but my understanding is that a jig looks like some steel donuts and a big precision machined tube. two donuts go in the 3rd member bearing caps, and the others go at the ends to hold them in line during welding. here's a non-ford example.... http://the-mite.com/mite22.htm
made mine,but looks sort of like the one mittler brothers sell but i use a dedicated pumpkin with the pucks in it permant,so i use this nine inch pumpkin on all nine inch rears to narrow them.
I Saw A Guy Selling A Kit At The Last Swap Meet. It Looked So Simple. The Same Principle As The M/w One Shown Above, Only For A 9 Inch.
Casey - My son (a qualified and professional metal fabricator) recently narrowed a 9-inch for me to use in a nostalgia altered roadster I'm building. He came up with a pretty simple and effective way to do it - without an expensive jig. If you're only doing one rear end (that is, not intending to do lots of them as a business), it might be worth looking at. Do a search for my posts and check it out. It was fast and simple and there are photos. Good luck!
For the digger I used (borrowed) a Narrowing Jig. For my old truck I did this method: I cut off the end of the tube - leaving about 3-4" of tubing still attached to the bearing end. Removed the amount I wanted to narrow from the tube still attached to the rest of the housing. I slide a piece of steel tubing (maybe 3/16" wall) into the tubing. I heavily beveled the ends to be welded. Using a couple pieces of angle iron I clamped them in place - straddling the section to be welded. I put 4 heavy tack welds around the tubing. Let everything cool remove angle iron "fixtures" and checked for straightness using a straight edge. With a friend helping rotate the housing I continuously welded it with the first pass penetrating into the interior sleeve. Second pass finished it off. Weld was virtually flush when it was finished. I added several rosette welds into the sleeve as well. Overkill - yes....am I gonna worry about it - No! And because I am cheap I then resplined the axle myself.
I have narrowed hundreds of housings over the years. A couple of the methods described here will work fine., but... a narrowing jig will allow you to find a bent rear end housing, which at least one tube in 9 out of ten rear end housings will have. I check every housing before they are narrowed, and more than likely at least one tube will be out of whack. It is best to use a housing jig as a narrowed bent housing will be a narrowed bent housing. You might not think your housing is bent, because most axles will still slide in pretty easy until you check it with a housing jig.
Dutchman's motorsports has a narrowing jig for $595 http://www.dutchmanms.com/8_tools.html the guy that narrows rear ends for me made his own jig..and works so cheap that it is just easier to have him do it
This is a great thread and thank you all for the info... I looked up stan 292's thread about he and his son narrowing a rear. That's here: http://www.jalopyjournal.com/forum/showthread.php?t=124310 It contains all of the info that came up here and then some other considerations...really helpful in my opinion. Also, here is the Mittler Bros. site, if anyone is interested in seeing what a commercially available jig kit looks like: http://www.mittlerbros.com/ Click on "Rear End Index" on the left and then there's a picture of a jig kit you can click on for more info. There is an instruction sheet available for viewing there as well, which reenforces alot of what was said here and in stan's thread. HAMB for president...this place rocks. Casey
We sent the axles off to Moser Engineering in Indiana for narrowing. We narrowed the Rear End housing ourselves. I used a peice of Solid round Rod (Jig) just a little bigger then the inner diamater of the axle bearings inner diamater. We then turned down the ends to get the bearings on it after the length was cut down. Put it in the lathe to check for run-out and clean that up from one end to the other. Cut the axle housing perfectly square to the tubing. Then cut the desiered amount ouf the the length of each side. Use the lathe to insure perfect squarness and to grind a deep "V" groove to lay the weld into. Put the inner jig in. Put the outter ends of Bearing cups on. Beat the bearings on, which squared it up. Welded a little at t time with high heat, short welds. Beat the inner jig out. Recieve axles back from Moser. Install spring perches on housing.
I'd be suspicious of any housing that was lined up on the outside of the tubes instead of from the bearing bores. Not saying it's impossible but if you look at enough factory housings you'll see how the ends can be way out of line from the tubes. I made a jig 30 some years ago with a length of heavy wall 1 3/4" (I think, I'll go measure it later) c/moly tubing and made whatever donuts I needed from 3/4" or 1" aluminum. Cleaned up the old axle ends in the lathe or used new ones. The donuts are snug on the tube so you can tell by turning the tube if everything stays in line during welding. Since I don't have a lathe or access to one now, I sent a housing to Moser. It was quick and cheap so if someones just doing 1 it may be worth checking with them.
I narrowed one, but having never done it before i did it a little differently. I cut the weld that holds the tube to the center section and slid it out. I then cut off the proper amount from the end of the tube that was in the center. Slid it back in, put a couple tacks on it and took it to a local shop that has a jig and they put it in the jig and did the welding. They let it cool on the jig overnight and the next morning it spun perfectly on the jig. The owner of the shop said he'd never seen one narrowed like I did. it seemed simpler than cutting the bearing end off and trying to get it lined back up straight.
I've always thought about doing it that way - the problem is that you can't do that with all rear ends. The Ford 8" & 9" along with the early GM's that we like basically anything with a removable "pumpkin" which has an all steel housing can be done like that. I'd be interested in attempting this one day. The later stuff mostly have Cast center sections with pressed in axle tubes so you wouldn't be able to do it that way
I bought a "book" of instructions from a guy on E-gay, PM your address and I will share it with you! He sells the "pucks" and things to make a jig so I don't think he would be pissed if I share.
A guy who narrows them professionally in a local shop for lots of drag racers has a homemade jig that consists of a 2" diameter solid rod of hardened steel that fits into machined inserts in an old pumpkin and there are machined pieces that slip over the ends of the rod to hold the flanges perfectly square. He only uses new end flanges. I think he has a jig that allows him to roll the axle housing while he welds it with some big sucker of a Mig gun that leaves a bead about 1/2" wide. He does a real nice job. A lot of old axle housings have bent tubes, so you can't trust the tube to be straight. You have to go by the position of the pumpkin. Getting the end flanges square to the bearings in the pumpkin is more important than how it looks.
Hey, Something to keep in mind is that some of the early 9", that had the smaller axels, the 28 spline can't be cut down, not enought meat on the ends. Make sure of what you have before you go to all the trouble of cuttin down a housing. Swankey Devils C.C.
I do this professionally. We use a 1.5" precision machined bar with machined donuts that have the same dimension as the carrier bearings inside the pumpkin to center and square the bar. Two more donuts machined to the same dimension as the axle bearings at the ends of the tubes slide onto the bar after it is seated in the carrier with the bearing caps torqued down. When you slide the outer donuts up to the housing ends, you want them to line up real nice and slide in with a little twisting. That tells you the axle is straight. If you have to use a mallet to get them into the outer bearing races, it's getting a little iffy. IF we are able to spin the bar by hand with all 4 donuts in their repective bearing pocket, we will finish out a housing. To get here on a housing that you have cut down, you should check it in this manner before you cut it. If nothing scares you enough to look for another housing, cut it to length leaving the original material on the housing ends. (look for the factory weld). You can mock up all the pieces on the bar to check your dimensions and square the cuts so that the gaps are tight. Remember that it's hard to fix one where you take off too much material. Measure many times and cut several to work up to the mark. As you mock things up, you WILL have misalignment. I have never seen a tube so straight that you wouldn't see a step in the weld unless it was straightened some. Before you finish squaring the joint and tack the ends back on, you can use a torch, gas or tig, to heat a spot on the long side and pull the tube back straight. Heat a spot about the size of a half dollar and cool it fairly quickly with an air gun to shrink it up. Do this on the side you want the tube to move to. It may take several tries to get the tube close. Bevel the edges of the joint a bit and tack it on opposite sides until you have 4 to 6 tacks on it. Then PULL THE BAR OUT and lay in the heat and filler an inch at a time, swapping ends of the housing and sides of the tube to limit the total heat you put into the tube. When you are done, housing cool, slide the bar back into the carrier and repeat the alignment test we started with. Use the torch to put any fine tune on the housing. Remember that you should be able to spin the bar by hand with all the donuts in place. You can shortcut this process all you want. You will get out what ever you put in. This is the same process we use on V6 cruisers, rock crawlers and 2500 HP ProMods. This is the best way to do one by hand. I have seen trick robot welders do one joint start to finish, but they move really fast and use minimum heat. I've seen tubes cut in a lathe. That's neat. We don't have one. Would I ever do one of my own without the bar? No way. Oh, remember to use an angle finder to get an index on the housing ends and their relation to the pinion angle so you can put them back and have them both match.
Great info all, scottybaccus that sounds spot on...I suppose running down the highway for hours at a time, will bring a quick end to misaligned bearings, maybe not breakages, thats why most are getting by with the lesser method.......but sometimes its about getting by..........Ive lost faith in a lot of so called "performance shops" and having a go myself saves money and ends up a better product......dont know if Id do a drive shaft though.......good thread fellas...........Bert
I had my rear end done but used some unconventional pieces. ford 9" center and tubes, 74 Olds Delta 88 ends and axles resplined to fit the ford center section. the Olds axles are larger diameter than the fords and tapered consistently unlike the large step down on ford axles. The Olds bearings are larger than the big ford bearings. served up 2 years of hard launching passes on the strip, ate up several trac locks used a spool for a while then back to a trac lock and no issues with the axles. My rearend guy has been machining for 40+ years and heat treated the resplined axles by hand with a torch.
Having done both - Without a doubt the alignment bar is the best method out there. Like most things in life there is more than one way though.
I use to do a lot of these back in the 80's during the "pro street" fad. Gotta tell ya, I don't think it's worth the hassle to do one yourself unless you really want to. Moser does it so fast and cheap I sold my jig and started ordering them from him, I could order one (no core needed) the size I wanted cheaper then what I was charging my customers to do it.
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