U joints- determine what to buy

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MooseStang

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Moose has a vibration that I believe may be u joint related.  What all information need I need to gather to purchase the correct ones?  Q code, 4 speed, 3.25 traclok. Anything else? Moog, Spicer?

 

Bentworker

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I don’t know if there is a reputable driveshaft shop near you but the easiest thing to do may be to pull it any hand it to them.  They swap the u-joints, then check the balance and touch it up if need be.

If you go DIY I’d just press the old ones out, measure them and go pick up some new spicer ones.  You should be able to measure cap diameter and cross size to determine what you have, even if they are still on the car.

 

Don C

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I agree, make sure you measure to make sure, you never know what P.O.s have done or mismatched. Measure both legs of the crosses, some are are what I call oblong, two different lengths. I would remove them and take them to the parts store, for comparison. And yes, a good quality like Spicer are a must.The NPD paper catalog is a good reference:

U-Joints NPD.jpg

 
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Hemikiller

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Ford used two different size driveshafts on the 4 speed cars, depending upon rear gears. 3.25 cars were supposed to get the 1310 joint and 3.50 cars the 1330, but there have been variances in what actually went out the door. The NPD listing leaves out the 3.25/3.50 gear differences on the 351 applications. You car *should* take the -6 & -7 joint. 

The only error I see in the NPD chart is the -7 u-joint should have a 1 1/16" and a 1 1/8" cap diameter. 

Lots of things get swapped over the years so best to pull the shaft and measure. 

E & F are the 3.25 joints, G & H are 3.50 

mustang_ujoints.JPG

 

MooseStang

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It appears Moose has had a gear change.  Marti says 3.25, but I'm counting 3.5.

 

timachone

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Again: measure, measure, measure. And be prepared that from and rear are slightly different. I went with Spicer, HD, non greasable, as original 

 

MooseStang

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I started out for a drive yesterday and not far from home, the vibrations started again, feeling worse than before.  I think I may have even heard a noise from the rear, was in some traffic so I'm not certain.  so today I decided to do another inspection of the rear end.  I "believe" there's an issue with the pinion bearing, but I'd like the opinion of the experts before proceeding any further.    Try to find how to upload the video.   Stay tuned.

 

73MustangCoupe

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I'm not an expert, but I have rebuilt a Ford 9 inch, and that pinion should be rock solid and not moving around like that.  

 

MooseStang

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Great, into the uncharted I go.  I'll welcome all advice. The marti says it should be 3.25, but its 3.50.  I don't know the spline count.

 

Bentworker

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You can go budget or wild.  Once you get it apart ring and pinion reuse or replacement will be apparent.  I’ve set up several sets of gears, luckily the 9” is one of the easiest to set up. 
 

On the other end of the spectrum you could buy a new complete third member. 

 

MooseStang

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I still debating on whether to try to pull this myself.  I don't have a lift, only floor jack, stands and a set of rhinoramps.   Also would be doing this by myself.  
I've also had someone else tell me they think it looks like the joint not the pinion.  
If I did decide to pull the shaft and I needed to then reinstall, how difficult will it be to get it to line back up to the trans?  I'm a little concerned about getting things lined back up.
I also found some underneath pics from when I purchased, does anything look out of the ordinary?

176697342_955825908491465_5914367485199094016_n.jpg

176724893_955825871824802_8774824809721724141_n.jpg

 

71ProjectJunk

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You can definitely pull the driveshaft out by yourself with just some stands. You can't really mess this up, it is about as straightforward of a job as there is. There is no alignment to the shaft on the tranny end, it can slip into the transmission any which way, the only thing that needs to be aligned is the rear u-joint, and that is a no brainer as if it is not aligned you cannot bolt it in. To remove the shaft you just take out the 4 screws on the 9 inch yoke, remove the u bolts, and then push forward on the driveshaft so that it will fall free from the rear yoke. You then just pull it out from the tranny end and it is on the floor. You then change your u-joints, which is the hardest thing here. After changing the u-joints, you just get under the car and push the driveshaft into the transmission, it just slips in, and then push it back onto the rear yoke, put your u bolts back in and tighten it. It is really a straightforward job. If you put the tranny in neutral, you can slip the driveshaft into in, and then move it around to align it with the rear yoke. There is no way to mess this up...

 

Bentworker

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It is doable with jack stands.  
 

I watched your video again, you can clearly see the gap changing between the yoke dust shield and the 3rd member casting when you are reefing on it.  I hate to say it but I am 100% sure your pinion bearings are toast.

It is a pretty common issue with older 9” axles from wear, or improper pinion seal replacement.

 

MooseStang

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Ok, so now comes more questions.   I "think" I'd like to change from the current 3.50 back to the original (so says Marti) 3.25.
Should I pull the 3rd and have it rebuilt?   Or buy one already done?   Or is there another option?  I do not have a press and have never rebuilt an diff.

 

Aus73Mach1

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I agree, the pinion bearings in the video are clearly shot and the diff would be noisy. There should be no movement sideways there and obviously no preload on those bearings. Diff rebuild is not that difficult. Replace all bearings in the 3rd but, you will have to check and/or correct the contact pattern on the crown wheel/pinion gears, set the correct backlash and then apply the correct pretension on the pinion bearings. If you want to change the 3.50 to 3.25, that is a different gear set so the easiest way may be to look for one already done.

 

MooseStang

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Where should I look for a ready built 3rd? And the only thing that I'll need to identify on mine is the spline count, correct?

 
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Bentworker

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Spline count and yoke style/ size  / length.

Local rebuild is always an option.

Summit racing / Strange / Currie can all sell you a new unit set up just how you like.

 

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