Narrowing my own 8.75. Questions.

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Scooper

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Doing this work at the local college machine shop & welding lab. Have access to all of the correct tools.

Question 1: What is the angular relation of the spring perches to the axle center section? Perhaps to be more precise, the yoke output? Are they to be parallel?

Question 2: The notched sections of the flanges at the end of the axle tubes. Same question as the last. Are they to be oriented on top with the flat being parallel with the yoke?

I ask these questions because, the axle housing I have, the spring perches and flanges were at different orientations that those I have seen in 8.75 photographs.

My understanding is that this axle came out of an a100 at some juncture. It will be repurposed to a 1966 Valiant sedan, with intent to be as accurate as possible.
 
Contact Cass at Dr. diff. He is a member here as well but I don't recall his handle.

He makes A body 8 3/4 housings from donor housings and will have the info.

If you don't get an answer I have a housing I can measure for you.
 
Ok, I will try to look him up later today.

Should probably have posted to the Transmission/Drivetrain board.
 
Scooper said:
Doing this work at the local college machine shop & welding lab. Have access to all of the correct tools.

Question 1: What is the angular relation of the spring perches to the axle center section? Perhaps to be more precise, the yoke output? Are they to be parallel?

Question 2: The notched sections of the flanges at the end of the axle tubes. Same question as the last. Are they to be oriented on top with the flat being parallel with the yoke?

I ask these questions because, the axle housing I have, the spring perches and flanges were at different orientations that those I have seen in 8.75 photographs.

My understanding is that this axle came out of an a100 at some juncture. It will be repurposed to a 1966 Valiant sedan, with intent to be as accurate as possible.
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Following. Would love to see your progress -- start to finish.
 
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Do not weld the spring spring perches until the housing can be mocked in the car. That’s what sets your pinion angle and is ride height dependent. A truck with 6” of lift and a valiant that’s 2” dropped will be entirely different. Don’t pick an arbitrary number and stick em there, it will be wrong. As for the housing ends, the only important factor with those is the orientation of the brake bleeders once everything is assembled. They need to be pointed up.
 
^^^ this! Use the springs and U bolts to hold the axle onto the floating perches and get the car on the ground. Get the nose down 3 -5 degrees off the trans plane or whatever ends up working for your spring rate and then tack the perches. remove and full weld in 1" increments to keep heat down. Are you resplining the axles yourself? Take some pics! When I welded the shortened axle tubes (I sectioned the tubes close to the pig) I used the axles and bearings to set my tube alignment. a few tacks, measure again and bead weld. This was on a Ford 8.8. Probably not the most accurate but it tracked straight and didnt break. I would do the trimming on the ends next time but this one had a bunch Explorer mounts toward the end and I could not get a pipe cutter on it to make a 90 degree cut out there.
 
pishta said:
^^^ this! Use the springs and U bolts to hold the axle onto the floating perches and get the car on the ground. Get the nose down 3 -5 degrees off the trans plane or whatever ends up working for your spring rate and then tack the perches. remove and full weld in 1" increments to keep heat down. Are you resplining the axles yourself? Take some pics! When I welded the shortened axle tubes (I sectioned the tubes close to the pig) I used the axles and bearings to set my tube alignment. a few tacks, measure again and bead weld. This was on a Ford 8.8. Probably not the most accurate but it tracked straight and didnt break. I would do the trimming on the ends next time but this one had a bunch Explorer mounts toward the end and I could not get a pipe cutter on it to make a 90 degree cut out there.
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This is just a naked housing. I'll be ordering axle shafts/bearings etc once the work is done. Already have a 741 chunk and 3.23 gears for it.

Thanks for the information, folks. It's a lot to take in but it all helps. Keep it coming!
 
Also I know this sounds incredibly primitive and barbaric, but, my plan to keep the tubes straight was literally to ratchet strap 4 lengths of box or angle iron offset at 90 degrees each to the cut/remaining sections to keep them straight & flush. Then just progressively tack them around. Leaning towards either double-shielded flux core or E6010 for the full weldament.

Forgive my backyard butchery. Used to working in the driveway, haha.
 
TT5.9mag said:
Do not weld the spring spring perches until the housing can be mocked in the car. That’s what sets your pinion angle and is ride height dependent. A truck with 6” of lift and a valiant that’s 2” dropped will be entirely different. Don’t pick an arbitrary number and stick em there, it will be wrong. As for the housing ends, the only important factor with those is the orientation of the brake bleeders once everything is assembled. They need to be pointed up.
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Dumb question: if the suspension hardware is stock, would not the 5 degrees as quoted be sufficient?
 
I’ll also add this, even though no one does it and many people have had good results not doing it, including myself. The only way to keep axle tubes straight and ends square during shortening/welding is with an alignment bar and the correct bearing pucks installed at the outer ends and through the diff.
 
TT5.9mag said:
I’ll also add this, even though no one does it and many people have had good results not doing it, including myself. The only way to keep axle tubes straight and ends square during shortening/welding is with an alignment bar and the correct bearing pucks installed at the outer ends and through the diff.
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10-4. Don't have access to those goodies, just the labs + tools/machines. Also trying to keep it low buck, so, we'll see if I can't come up with another way. Thankfully I have an essentially unlimited supply of oxyfuel to work with also, so, I can do as much preheating as I feel I need to help prevent uneven contraction.
 
The angle iron trick "CAN" work if you were working with tubes on a more traditional style rear end like a ford 8.8 or dana 44/ dana 60 etc. where you have a center piece that holds the gears and then 2 tubes get pressed into it. Still not the best option in that case but it is possible. The mopar 8.75 is formed sheet metal and I don't think any length of it can be considered straight enough to go based off that. These rear ends need a full and proper jig like has been mentioned above to do a proper narrowing. That being said, I have seen videos of people making the majority of the jig themselves then having a local machine shop lathe up some pucks for them so that can be an option as well.
 
TT5.9mag said:
I’ll also add this, even though no one does it and many people have had good results not doing it, including myself. The only way to keep axle tubes straight and ends square during shortening/welding is with an alignment bar and the correct bearing pucks installed at the outer ends and through the diff.
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This ^^^

and i personally like 70 18 AC using DC Positive Polarity for welding the tube ends on .
 
Mine was done with a similar jig. The end flanges are not centered exactly on the tubes. (Almost looks wrong) If they were on mine I probably wouldn't even get the axles in the chuck.
I then added a brace myself using an Eyebeam. (Caveman style)

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Scooper said:
Also I know this sounds incredibly primitive and barbaric, but, my plan to keep the tubes straight was literally to ratchet strap 4 lengths of box or angle iron offset at 90 degrees each to the cut/remaining sections to keep them straight & flush. Then just progressively tack them around. Leaning towards either double-shielded flux core or E6010 for the full weldament.

Forgive my backyard butchery. Used to working in the driveway, haha.
Click to expand...


I can’t think of a reason to use dual shield (flux core) wire. Just use hard wire and send it.
 
Here’s a tip, when I narrowed my 8-3/4 I used the ford big bearing housing ends from Moser which allowed me to use the Wilwood ford brake kit. At the time it was about half the cost of the mopar kit. Same brakes.
 
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