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Well it's back home and it's broken!!

After work my wife and I went and picked up the Mach 1 from exhaust/alignment shop. First of all I'm not going to lie was a little nervous to drive it home in rush hour traffic. This would be it's first drive of any distance. At first I was driving it like an egg watching the oil PSI and temp like a hawk. 55 at idle and 80 at cruise. The temp stayed solid at 180 on a 92 degree day in stop and go traffic. It wasn't long the nerves where gone and I started to run it up threw the gears. Last light before my neighborhood with my wife right behind me it was time!! Took off in 1st made sure the clutch was engaged then gave the throttle a jab spinning tires. Did a nice easy shift to 2nd making sure the clutch was engaged but this time the throttle got stabbed blowing the rear tires off. Laughing my ass off I made the left into the neighborhood. All was good till I made a right on to my street the rear end felt like it was binding and was making a thumping noise. OH CRAP what's that! Driving strait it seems fine. Turning left seems to be binding but no noise. Turning hard right it really binds thumps and jerks the car. I installed Speedway motors HD axles in the N case 9 inch during rebuild. Could I have broke the right axle? I got to work tomorrow so it will be Sunday before I can look at it.
 

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Well it's back home and it's broken!!

After work my wife and I went and picked up the Mach 1 from exhaust/alignment shop. First of all I'm not going to lie was a little nervous to drive it home in rush hour traffic. This would be it's first drive of any distance. At first I was driving it like an egg watching the oil PSI and temp like a hawk. 55 at idle and 80 at cruise. The temp stayed solid at 180 on a 92 degree day in stop and go traffic. It wasn't long the nerves where gone and I started to run it up threw the gears. Last light before my neighborhood with my wife right behind me it was time!! Took off in 1st made sure the clutch was engaged then gave the throttle a jab spinning tires. Did a nice easy shift to 2nd making sure the clutch was engaged but this time the throttle got stabbed blowing the rear tires off. Laughing my ass off I made the left into the neighborhood. All was good till I made a right on to my street the rear end felt like it was binding and was making a thumping noise. OH CRAP what's that! Driving strait it seems fine. Turning left seems to be binding but no noise. Turning hard right it really binds thumps and jerks the car. I installed Speedway motors HD axles in the N case 9 inch during rebuild. Could I have broke the right axle? I got to work tomorrow so it will be Sunday before I can look at it.
If you had a broken axle you'd really know it, there would be an hellatious noise driving in any direction. Sounds to me a differential issue. Jack the rear of the the car and manually rotate the rear wheels feeling and listening for obvious /abnormal sounds then troubleshoot from there. What differential are you running?
 
Mike they make an additive to add in the rearend for positive traction units. I am sure you know that but sometime after a long build we for get to add it.
 
If you had a broken axle you'd really know it, there would be an hellatious noise driving in any direction. Sounds to me a differential issue. Jack the rear of the the car and manually rotate the rear wheels feeling and listening for obvious /abnormal sounds then troubleshoot from there. What differential are you running?
A ford N case 28 spline.
 

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I got the wipers installed were they belong with help members from the forum. Thanks!
Installed the hood as well. The twist locks are giving me a bit of trouble.
Dropping it off Saturday morning at the exhaust/alignment shop. So looking forward to it being quiet. Open headers has been fun but it's time.
Mine is going in on Tuesday. Do you have an under pic to see how it all goes? Fairly sure MidasMuffler guys haven't seen many 50plus cars. Neither have I.
Mike they make an additive to add in the rearend for positive traction units. I am sure you know that but sometime after a long build we for get to add it.
Do you know the name of the additive please
 
Took the Mach for a ride this morning to confirm the noise. Yup it's still there. Came back to the house and put it up on jacks to see what's going with the 9 inch. Tried to let it idle in gear didn't really see anything. Next tried to rotate the tires by hand. About every half turn you can feel it bind up pretty good and I had push through the bind. Pulled the axles out to find hot spots in the end of them. Apparently I didn't cut them short enough. I measured the original axles not thinking the car was a 3.00 open diff. Going to grind them down a bit then reinstall them and hope for the best.
 

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Got back to it on Sunday. I took a measurement the pin outward to the outer bearing surface. The ales were a tick to long. I took of about a 1/8 of an inch both axles and put it back together. Hoping for the best on that.

My OCD kicked in I couldn't handle the exhaust cross bar not being painted. Spent 2hrs taping everything off to paint it and subframe connector traction bar welds. Well worth the effort. Obviously overspray was going to be unacceptable.
 

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Have you tried rotating the pinion yoke with the axles and driveshaft removed? If not, I suggest you do so. If the tight spot is still present, the issue is internal to the differential.

An excessively long axle would bottom out on the pinion cross pin. The result would be that the axle bearing would not fully seat in the axle housing. The axle retaining plate presses against the OD of the bearing. Any binding, due to axle length, would be coming from the axle bearings unless one wheel was turning more that the other. In that case, there could be noise due to binding at the end of axle and pinion gear cross pin. The effect of such binding would likely not result in anything you could feel...probably even hear.

When is the noise present? Is it when you made any sort of turn with the car? Does it make the noise going in a straight line? I understood your config to use a Traction Lock style differential, but I didn't read the entire thread. Noise from insufficient friction modifier will produce a groaning sound and sometimes accompanied by a chattering cadence. Backing up can make more of a low pitch whine that may sound like gear noise. It will typically make more noise in one direction than the other.

In my experience 1 4oz bottle of friction modifier works with used clutches, but new ones may require an additional half bottle to quiet things down. Do you know if the clutches were soaked in friction modifier prior to assembly?
 
Have you tried rotating the pinion yoke with the axles and driveshaft removed? If not, I suggest you do so. If the tight spot is still present, the issue is internal to the differential.

An excessively long axle would bottom out on the pinion cross pin. The result would be that the axle bearing would not fully seat in the axle housing. The axle retaining plate presses against the OD of the bearing. Any binding, due to axle length, would be coming from the axle bearings unless one wheel was turning more that the other. In that case, there could be noise due to binding at the end of axle and pinion gear cross pin. The effect of such binding would likely not result in anything you could feel...probably even hear.

When is the noise present? Is it when you made any sort of turn with the car? Does it make the noise going in a straight line? I understood your config to use a Traction Lock style differential, but I didn't read the entire thread. Noise from insufficient friction modifier will produce a groaning sound and sometimes accompanied by a chattering cadence. Backing up can make more of a low pitch whine that may sound like gear noise. It will typically make more noise in one direction than the other.

In my experience 1 4oz bottle of friction modifier works with used clutches, but new ones may require an additional half bottle to quiet things down. Do you know if the clutches were soaked in friction modifier prior to assembly?
Now that I put all back together I can rotate the axle by the wheel stud easily forward and back. I'm thinking maybe the backing plates were loose because the axle retaining plates weren't tightening enough.
 
Happy to update the progress of the past few weeks!

Been working on the Mach1 pretty much every day. I replaced the shifter and screwed down the console. The shifter MDL sent with the trans was way to tall. The new shifter is way better. Moved on to the instrument panel column caller and kick panels. Finally got the hood twist locks adjusted! That took hours. Wired the exhaust cut outs. Check out the video. Now for the best part. Put the the car back down on the ground and went for a 40 minute ride. NO noise from the 9 inch! Can't tell you how happy I am.

That brings me to last Friday night. It was Mustang / Cobra night at my local cruise night. Cruising Grand. The wife and Took the Mach 1 Down for the first time. I can say I'm a little humble by all the positive comments that we got. One particular comment was " you just don't see theses cars takin to this level nice job " It maid the long road worth it. Still not done yet but getting close.
 

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