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Ford 9" Questions...

8K views 47 replies 3 participants last post by  big gear head 
#1 ·
Hi All,

I have a Ford 9" 4-pinion traction-lok unit that I pulled apart today. This unit was advertised as "ready to run", but while disassembling it was found to have all bolts just above finger tight. Everything inside looks good (even the clutches) except for two things. The sheetmetal spring coverplate is broken, and the outer shell of the case has a few places where the clutch tab retainer slots are machined too close to the ring gear bolt holes and you can see daylight through these spots. Is this normal? I've heard Currie makes a billet cover plate, but haven't seen it available separately and don't know if it'll even "bolt on" without additional machine work. Does anyone know for sure or have a part number?

Thanks!

Russ
 

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#39 ·
#40 ·
OK, round #3 with this thing...

Removed the springs and assembled the unit with a single 0.020" shim. Burnished the clutches 20 turns in each direction by setting a wheel/tire on the floor, sticking an axle in the hub, placing the diff on the axle, sticking the other axle in the diff, then another wheel/tire on that axle, then round and round she goes! This was easy with little resistance. Added another 0.020" shim and it would not budge. Removed that shim and added an 0.013" shim (where I was originally). This was about like the resistance in the Tom's vid with the exception of one tight spot for about 30° of rotation. After making 20 rounds in each direction, things got no better, so I assembled the diff with 0.033" shims and the tight spot. When I was seating the ring gear, it seemed to want to "break away" and rotate around 45 ft-lbs again. My shoulder quit before I did, so it's waiting on a "mood adjustment" to torque the ring gear bolts and reassemble it. Is this as good as it'll get?

One thing I did ponder on, the thrust washer just "floats" until the clutch pack wears enough for the clearance to disappear, correct?

Russ
 
#42 ·
I got wondering about it and did some measuring. Here it is drawn in orange. The clutch pack, even with no shims, is tall enough that the washer doesn't feel any load. With normal shimming, it should be around .060" loose. Theoretically, until the clutches go away...

I got this e-mail from QP tonight:

Russ-
The new aggressive units come with 250 ft/lbs of breakaway on the clutches and the new smooth units come with around 150-175 ft/lbs of breakaway on the clutches. We test it by putting a splined section into each side of the unit and torqing one side until it slips.
Looks like I'm still ways off on how to do this. After watching Tom's vids, I can see what would happen if a unit is overshimmed. I have no idea how QP is getting their units to 250# without overshimming them. Guess I should have just bought another NASCAR locker off E-Bay and not had to go through all this...

Russ
 

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#44 ·
Ya know? I did not! I just had the pinion-side axle in a vise and nothing in the clutch side. I guess when it slips like this, it throws off the alignment between the side gear and clutch hub... Thinking back, it was pretty tight when I had both axles in it and was (trying to) turn the assembly using the tires as handles. But I'm pretty weak in the arms right now so thought it may have been me. Got an appt. with the shoulder doc Wed to at least get a diagnosis. I did find a diagram of the factory tool with dimensions, so may make one to try out.

Russ
 

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#45 ·
OK, looks like I'm gonna be out of commission for a few months. If I can find this thread when I get back to it I'll update it, otherwise I'll start over...

BGH, what do you use to check the breakway at the axle? Is there some kind of adapter to go from the lug studs to a torque wrench?

Russ
 
#47 ·
BGH,

I was bad! I went out and finished torquing the ring gear bolts and setting the backlash (all with my left arm). Using my homemade yellow "paste" I changed pinion shims from 0.027" to 0.038" to 0.050" and could not discern any change in pattern, at all. After wiping it all down, sticking in a single 0.020" shim, setting b/l at 0.008", and using some Prussian blue compound, this is what I'm now looking at. By then, my arm was getting sore so I quit. The coast side is fairly pronounced, but the drive side doesn't show as well. What's the verdict?

Russ
 

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