Narrowing 8 3/4 details

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sdahmer

sdahmer

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So I decided to narrow an 8 3/4 for my Dart project, I got the housing off a C-body for $60 at the junkyard and a pair of stock A-body axles from another FABO member for $50. So far so good, but I have a few questions:

1) When shortening a driveshaft, does it need to be re-balanced?
2) Can I clock the new spring perches using the old ones or do I need to check the pinion angle?
3) Has anyone seen the following musclecar episode? Tommy narrows a housing without a jig! Is this wrong or can it be done? musclecar
 
1) if your good and clock the u joints 90 degrees from one another and keep it straight then all is good
2) if using the stock style springs then you could clock it with the old but it would be better with the new springs because they may be different, but that is where the degree shims would come into play
3) i used a big chunk of angle iron and clamped it tight on both sides and then started tacking it together. I also stuffed a 1.5 inch bar through the housing and used a empty case with bushing in the bearing locations, just to be sure it stayed straight. (you could go without the bar)
 
Thanks! I've seen someone on another forum use the angle iron trick, I think I might try that approach. They also used a pipe cutter to get near perfect cuts, which I really liked. I like to do as much as I can on my own, It's why I got into cars in the first place.
 
1. You need to see your local driveline shop for that, and yes ANY time a major component is replaced it needs balancing
2. You can use the original rear as the template by measuring the angles from it
3. Well thats how many shops do it, but like i said there are 10 ways to do something and only 1 is right. The problem with that is there is too much movement and you won't have it right, and the 2nd is you can't check it and see. Also all brackets get installed 1st as that welding will move the tubes.
 
I used a pion angle tool & got all the info from a mopar chassi book. Good luck
 
All above info good...when I did my rear end shortening I used a trk housing,cut off the ends at the weld joint with a 14'' cut-off saw with metal blade like muffler shops use,I did this by removing all the 3rd member studs[and axle end studs] and laying it face down on some short 2x12's to match level of saw,at this point you dont have to worry about squaring the end tubes yet as you are cutting following the weld joint,I then took the cut off ends to a mach shop and had them turn the centers back out to tube size which if I remember right was 3'',and about 3/4'' depth so they could be slid over finished tube and welded,you will have to grind/sand the tube ends to clean them up and fitament and you want to test fit ends to tubes and you want them tight,I had a new set of ends for this project but I didnt like the design[butt joint weld ons] as to why I reused the originals turned down to fit over the tubes,made it alot easier to fit and square up and weld...I did not use a jig,just a pair of trk jack stands,3 small magnetic levels,one for middle of each tube and one for pinion area of 3rd member,a 2' square,some welding clamps and some blocks of wood to support the 3rd member when its all mocked up to keep it from rolling,also mocked it all up including the axles,3rd member and when I was satisfied with it I tac welded at 12-6-3-9o'clock positions then rechecked and welded with it all together after rechecking 99 times...lol...as to the spring perches I mocked it all up in car and set desired pinion angle and then tac welded.rechecked and then removed and done the final weld,sure I'm missing something here but this the basic rundown..this was not without its problems I ruined 2 housings[warped] before I got it right just my 2 cents worth...
 
For every person that tells you that you don't need a jig, there are 25 more people that will tell you the correct way. If you don't have a jig, box it up and UPS it to Moser, you will have it back in a week.
 
Thanks for the replies everyone! I wouldn't have considered narrowing the housing without a jig if it weren't for the musclecar episode. I think I might just buy the pucks on ebay, found a guy selling them for around $100, then you just buy the rod localy. I think it'd be cheaper than sending it off to someone.
 
69MOPE said:
For every person that tells you that you don't need a jig, there are 25 more people that will tell you the correct way. If you don't have a jig, box it up and UPS it to Moser, you will have it back in a week.
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Just to clarify I did not say you shouldnt use a jig,you should if possible ,just relating my experience with mine and it turned out good,it can be done on the cheap if you're determined and have the materials and the skills,I also built my own backbrace and all in my garage,would I do it again,probably not when you can buy one to size and with a backbrace already with perches ready to go for a decent price from moser but at the time I couldnt afford to do that so I made my own and by my own mistakes and sucesses and most of all by my own rules,and if you think about it the 3rd member and the axles are your jig....just got to be smart enough to figure it out,if I can,anyone with the right materials,mech and welding skills could duplicate it fairly easy...but if you have access and can get a jig by all means do so probably save you a bunch of time and agravation and it will be 'professionally done'
 
I've done my own and no you don't need a jig. I've even checked untouched 40 year old sock housings and not found them to be in alignment.
 
you can clock your pads by installing them clamped onto axle tube with the U bolts and rotating your axle to where you want it to sit nose wise. Once you are comfortable with it, tack them into position and them run a full bead once its out again. Run about an inch at a time alternating between sides to keep the heat down. The springs will make them sit perfectly in line with each other assuming your springs are good. I had an old mechanic tell me they made some rears a degree off to track better, sort of toe in. COuld be BS for all I know.
 
sdahmer said:
Thanks for the replies everyone! I wouldn't have considered narrowing the housing without a jig if it weren't for the musclecar episode. I think I might just buy the pucks on ebay, found a guy selling them for around $100, then you just buy the rod localy. I think it'd be cheaper than sending it off to someone.
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The shaft needs to be true and straight i use Thompson 440c, not all shafting is straight. Might as well do it by eye than use any type shaft.

It will be cheaper to have a shop do it, either locally or send it off in a truck
 
sdahmer said:
Thanks for the replies everyone! I wouldn't have considered narrowing the housing without a jig if it weren't for the musclecar episode. I think I might just buy the pucks on ebay, found a guy selling them for around $100, then you just buy the rod localy. I think it'd be cheaper than sending it off to someone.
Click to expand...

I agree that not all shafts are straight. A buddy pointed out a website that sells turned, ground and polished rod really reasonable. They claim a tolerance of no more than .001" runout so it should work great. I saw those pucks on E-bay also and was going to buy them but a buddy of mine that runs a scrap yard had someone bring in some that are really close to the right size and he has a lathe so I'm going to turn them down to the correct diameter and order a shaft from speedy metals. Here's a link to their page with a 1-1/4 rod. They have all sizes so if that's not what you need look around and you should be able to find it. Just make sure you stay with turned, ground and polished.

http://www.speedymetals.com/pc-1625-8232-1-14-rd-1045-turned-ground-polished-000-001.aspx
 
When using angle-irons you're just basicly copying the factory's (mis)alignments.
With a jig and internal bar you're actually realigning the outer bearings ends with the inner bearings in the 3rd member, like it should be done.

The angle-iron-way will work for most, but since you don't know anything about the bearingalignments, you might be prematurely wearing out the splines on the axles and bearings because of that.

Anyway, this is how I narrowed my own axle-housing...
http://www.bigblockmopar.nl/2012/01/8-34-rear-axle-narrowing/

And on the bottom of this page you can see a short text and pic how the driveshaft was shortened;
http://www.bigblockmopar.nl/2012/10/a518-overdrive-transmission-installation/

There's a little more involved in shortening a driveshaft but I don't have pics of that.
 
I had a old racer friend tell me "if the axles slide in, the housing is straight". He narrowed a lot of rear ends. tmm
 
toolmanmike the axles will slide in on severely off housings, the axles will slide in on ends that aren't straight, the axles will slide in on housings that are way off center.


Also, please do not shorten your shaft on your own, it will cost you more in the long run.

.
 
I think he bolted a angle iron to the flanges and measured both ends to get it square. He didn't shorten axles. They were always purchased. Yes the absolute best way is to have a pro do it. tmm
 
I had a c-body rear shortened by a local chassis builder and he spent a lot of time straightening the housing. It was either bent from years of use/abuse or might have been that way right from the factory. I try and do almost everything myself and could probably do it but I`m going to send the next one to the same guy to make sure it`s right! The axles just get sent to Moser.
 
If you check the factory housings, 99% of them are not straight. If I was gonna go to all the trouble to narrow a housing, I sure wouldn't use the angle iron method. Will it work? maybe.... is it done correctly? not a chance. I use a jig, and I usally spend more time straigtning the tubes than I do welding......
 
dodgedifferent2 said:
how did ole grand pappy do it 30 years ago?... just saying the pros learned from someone....
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Piss poor response..... I could hack a end off with a hacksaw and braze it back on, but it aint right. Its fine if you don't care if the housing is straight, the bearings are in a bind, or whatever, just do it the backyard way, its your car.:wack:
 
Well...everyone has their way right or wrong some work some dont,guess I got lucky,nice and straight no weird angles or bearing wear,yes it took a couple try's and a couple warped housings but hey I got it,heat is not your friend when your are cutting or welding on a housing,go slow on the cutting and welding dont get in a hurry,start with a good straight one if you can,as most are out of whack to begin with,but workable,it aint rocket science,fact is over the winter I am going to 'narrow' the remaining 6-7 good housings I have left to a-body size for they is a need for them,when they are done you will be hard pressed to know it wasnt a factory one,I have help this time around[machinist/welder] like I said it aint rocket science and aint worth arguing about and aint for everyone,not everyone has a bunch of parts laying around at their disposal to experiment with or the tools or skills so I can understand if you go out and buy a housing to modify you only got one shot at it and you got to make it count the 1st time around,if you screw it up then you are out the money not just 1 time but 2 times, so I would recomend to take it to someone with the ability and right tools to acheive your goal without the risks,aint trying to hack anyone off or saying my way is the 'only' way,or the best way,just relating my experience with my own and how I achieved it in above posts,so if that ruffles some feathers then so be it,we're supposed to be trying to help each other not beat each other up,and you can always just go buy one already done and wonder or do your own and know,I done the latter for I could not afford one from moser at the time nor did i have access to a jig or someone with the experience to help me,I did use some pipe and other odds and ends in the process that I didnt state in previous post but hey I aint making a video or a documentary was just saying it can be done,has been done and will be done again and I am proud of mine,was alot of work,time,effort and frustration and improvising but worth it to me and I aint no rocket scientist,it aint as hard as it's made out to be
 
replicaracer43 said:
If you check the factory housings, 99% of them are not straight. If I was gonna go to all the trouble to narrow a housing, I sure wouldn't use the angle iron method. Will it work? maybe.... is it done correctly? not a chance. I use a jig, and I usally spend more time straigtning the tubes than I do welding......
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I certainly agree that using a jig is the "correct" way to do it. Unfortunately not everyone has one so we have to improvise.
 
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