Shaft Length

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DentalDart

DentalDart

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Me again!:welcome:

I've been reading trying to avoid asking this question but I keep seeing different information and confusing the chit out of myself.

I'm hoping to get the rear end put together Friday, but I need to know what length to cut my shafts to. I've seen A-body housing 27 11/16, 28 3/16, won't work with cone style sure grip, yukons suck, buy from DrDiff and more.
Housing = A body 8.75 stock length
3rd member = 489 with cone style sure grip and 323 gears.
Old broken axle shaft with broken splines = 27 11/16in with 5x4in SBP
Current rear drums 10x2in

New axle shafts and brakes
Shafts- called Yukon (ran these in my Rubicons and they always did great, never had any problems) - was advised and purchased kit YAC 8.75 28-32 kit, cut to length axle shafts with 5x4.5 BBP

New Rear Drums and backing plates from 1988 Plymouth Gran Fury with an 8.25

So my question- do my axles work with the cone style sure grip? Do I cut my axles to 28in since that is the minimum length? Do I cut them slightly shorter at 27 11/16? Or do I cut them at 28 3/16? Or am I an idiot who doesn't deserve this car and should call the crusher now and get rid of it all? :BangHead::rofl:

Thanks pics

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Are you going to run Green Axle bearings (the sealed ball bearing type) or stock adjustable preload tapered cone/cup? The 5x4.5 backing plated will change things too.

I didn't even know they sold cut to length.
 
dano said:
Are you going to run Green Axle bearings (the sealed ball bearing type) or stock adjustable preload tapered cone/cup? The 5x4.5 backing plated will change things too.

I didn't even know they sold cut to length.
Click to expand...
So they give you 4 inches of spline to work with and you just chop saw the excess off? Cool! Sounds like a huge stress riser if its not supported though. Not sure what percentage of engagement do stocker have?
 
pishta said:
So they give you 4 inches of spline to work with and you just chop saw the excess off? Cool! Sounds like a huge stress riser if its not supported though. Not sure what percentage of engagement do stocker have?
Click to expand...

That and if your running thrust buttons on the diff, the install length is important and the perpendicularity to the splines. And then de burr the splines.
 
I have used the green bearings with factory length axles without having to remove the thrust buttons in the clutch unit or the thrust block in a cone type unit or an open diff. This is in A, B and E bodies. Kim
 
dano said:
Are you going to run Green Axle bearings (the sealed ball bearing type) or stock adjustable preload tapered cone/cup? The 5x4.5 backing plated will change things too.

I didn't even know they sold cut to length.
Click to expand...

Yes the kit came with green bearings, so I will be running those.

I will be running the 5x4.5 backing plate.

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Just checked and cleaned an 8 3/4 that had 1969 barracuda written on the housing. Never apart or modified. 3.23 gears and a sure grip and a 489 carrier. Small bolt pattern. Both axles are 27 3/4'' long from the outer flange face to the end of the axle. NOTE:::: they are 31 spline axles !!!! I washed the axle bearings in a round plastic container with gasoline covering the bearings, washed and rinsed several times, and blew off with air. Nice and smooth. I never use gasoline in the garage, always outside. No exceptions. New inner axle seals. Gambling on the outers.

Some of the aftermarket axles and aftermarket differentials have 30 splines.

Did a little checking on the green bearings a while ago. I think there are two different kits. One required cutting the axle, one didn't. More investigating is needed.
 
I thought that we were all going to compare the length of our shafts from the title.... :BangHead: :(
 
A) Make sure your axles fit the splines in the diff. before doing anything else!
B) If you are using the "green" bearings, then make sure the thrust button is not in the differential. You don't need it and don't want it. If you can't more or less see straight thru the splined axle holes in the diff., the button is still in there. Sometimes they fall out, but you'll probably need to knock it out with a punch and a hammer.
C) Assemble the axles, bearings, and backing plates to the housing without the carrier ("pumpkin") being installed. If the two axles hit each other in the middle, you need to cut them both off enough so they don't hit. If they are not hitting each other, you should be good to go. Unless they are too short and won't engage the splines in the diff. which should be easy enough to see. Not likely though.
 
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69_340_GTS said:
A) Make sure your axles fit the splines in the diff. before doing anything else!
B) If you are using the "green" bearings, then make sure the thrust button is not in the differential. You don't need it and don't want it. If you can't see straight thru the splined axle holes in the diff., the button is still in there. Sometimes they fall out, but you'll probably need to knock it out with a punch and a hammer.
C) Assemble the axles, bearings, and backing plates to the housing without the carrier ("pumpkin") being installed. If the two axles hit each other in the middle, you need to cut them both off enough so they don't hit. If they are not hitting each other, you should be good to go. Unless they are too short and won't engage the splines in the diff. which should be easy enough to see. Not likely though.
Click to expand...

Shouldn't I have a thrust block in a cone type sure grip? Which means... I have to take it all apart to get that pesky little thing out
 
DentalDart said:
Shouldn't I have a thrust block in a cone type sure grip? Which means... I have to take it all apart to get that pesky little thing out
Click to expand...
I couldn't tell you which ones have it, or don't. It's only needed if you have the old style adjustable axle bearings. And then you'd certainly have to get the axle lengths correct. But you don't need to worry about it. The thrust block, or "buttons" come out without disassembling anything. The two buttons are held together with a roll pin. Easy to drive it out with a punch, then the 2 halves separate and you should be able to slide them out.
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If you see ↓↓this↓↓ shiny-looking button when you look inside the diff., they're still in there:
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oldkimmer said:
Yes, if ur gonna take the block out of a cone unit u will have to totally dissemble it. Kim
Click to expand...
Is that what's being worked on? I guess so. Oops. So....
I guess you really need to make those axles short enough so they don't hit those buttons.
Could you measure (might need to do some calculating) button-to-button, add about 1/4" just to be safe, and then cut both the axles equally so that there is that much clearance between the cut ends when they are installed in the axle tubes?
 
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Ok I'll check it out when I get home! I have a test at 1 that I haven't studied for yet so have to do a little cramming.

Yes that's the thrust buttons. From reading other threads here, on B-bodies and moparchat I was under the impression that there were differences in buttons/blocks between the Mopar power-lock unit and the Borg Werner sure grip.

The powerlock has the buttons/block, which are two pieces that can be punched out. the Werner unit and open have a 1 piece block which requires the member to be disassembled and taken out.

Either way I guess this should be fun!

So after it's out is the consensus to cut the axles to 27 11/16, 28 or 28 3/16 inches? Lol .

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oldkimmer said:
Yes, if ur gonna take the block out of a cone unit u will have to totally dissemble it. Kim
Click to expand...

Thanks Kim!
I guess I'll have to see if I can find the tools to make the make the proper measurements when setting it back up. Or phone a friend
 
What your arrow is pointing at is a shaft those two gears are riding on. Thrust buttons are outboard of that. (Unless I've lost my mind).
 
I see it as the arrow is pointing to the spacer in the middle. Give Cass a call. Aka Doctor Diff. He will tell u for sure if u need to remove anything. I never have when I used the bearings with the snap ring. As per Cass. Kim
 
I only say to remove the buttons because on 2 different cars , with the clutch-type Limited Slip, the new axles with green bearings bottomed out on the thrust buttons well before the axle bearings were all the way into the axle housing. But my buttons were super easy to remove. I'd cut the axles before screwing around taking the diff. apart to remove the buttons on DentalDart's.
 
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oldkimmer said:
I see it as the arrow is pointing to the spacer in the middle. Give Cass a call. Aka Doctor Diff. He will tell u for sure if u need to remove anything. I never have when I used the bearings with the snap ring. As per Cass. Kim
Click to expand...
I see it now. Totally different spacer than what's in the clutch type Limited Slip diffs that I'm used to. And I can also see that it would be a pain in the butt to try and remove it.
 
Answer per DrDiff-

This is when using OEM Mopar brakes 5x4.5 bolt pattern drums in the rear, with A body 8.75 axle housing and cone style (Borg Werner) sure grip

Axle overall length from edge of spline to outer flange of axle shaft = 28.0 in
Axle length from edge of splines to outer bearing journal of the axle = 25.5in

This will allow you to run the axles without taking the thrust block out of the sure grip and will give you maximum of 1/2in of spline engagement.

You can add 1/8in or cut at 25.625in from edge of splines on shaft to journal and also take out the thrust block to get maximum of .625in of spline engagement from axle shaft to sure grip.
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* This is also for OEM stock A body rear end with Mopar rear drums, and Mopar power lock sure grip.

For clutch type (power lock) sure grips axles are cut to 25.5 outside edge of splines to journal giving you overall length of 28in. BUT you have to take out the thrust buttons/block to get engagement of the shafts into the sure grip unit.
 
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