Trans locked up shifting to second

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68valiantbb

68valiantbb

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68 valiant 400 727 manual shift .shifting to second gear rear tires locked up and shifter would not move . after a minute of moving shifter . it freed up and is ok . could this be an adjustment or bigger problems. thanks for any help. Tim { I was in it pretty hard when it locked up}
 
Did you just get done doing a burnout in first gear?
 
Tires start spinning in first then let off? Or anytime in the last few weeks, spinning or burnout in first gear then let off before shifting into 2nd?
 
yes last week end had to get out of it before 2nd gear.
 
You may have hurt the transmission. Never do a burnout and let off in 1st gear. Either run it out till it stops spinning on it's own or shift to second, then let off. I'm not a transmission guy, but have spent lots of money with him fixing my mistakes!
It has something to do with the drum or clutches overrunning and tearing up.
 
Hopefully someone else that does these will post a better explanation.
 
No not burnout just pulling out real hard tires spinning . then had to get out of it .
 
The burnout issue happens when, in first gear (where the sprag or overrunning clutch holds the rear drum) the wheels suddenly grab......like burning out in the water box and letting the car roll out to the dry sticky pavement where the tires grab. This shocks the sprag clutch hard enough to damage it, tearing the outer race loose. Most manual valve bodies also apply the rear band in first to help prevent this. This is why a bolt in sprag (much stronger) is a must in a performance build.

A damaged sprag will allow the forward drum to spin up to two or three times engine rpm on your next hard launch or burnout in first. The stock forward drum explodes like a grenade somewhere around eight or ten thousand rpm.
 
I am going to bet that your manual valve body is a trango tf3 modified one...... I have seen issues with this kit twice before and will not use them again. The kit causes the transmission to be so sensitive to linkage adjustment (due to the spool valve they supply?) That if everything isn't spot on the transmission could be slightly between gears, which engages two gears at once locking the transmission much like a trans brake. This happened on my friends bb duster (on a gentle 1-2 shift it locked up) and in my 72 swinger (incorrectly adjusted linkage, not fully into park, me standing in front of the car adjusting timing, I opened the throttle to about 2500 rpm and the car jumped the park pawl and launched at me crushing my legs and breaking my right femur).

It was no ones fault but my own, and I learned some valuable lessons and that day. My next 727 will have a proper aftermarket valve body, not one modified with the Transgo kit.

What has been modified in your transmission? Be careful! The sprag (or overrunning clutc) should be checked after any drive line failures or shock. A drum explosion will ruin your day....google 727 drum explode for graphic pics and details.
 
You could also have fractured or chipped a gear when it jammed. Bend a shaft...


Have you tried to drive it normally and check for any new vibrations going through the gears and slowly gaining rpm's?
 
Based on my past experience, the trans didn't release into 2nd gear. Had this happen a couple times on a trans I had a supposed local "pro" shop do. Both times the trans had to be torn down and gone thru. I would recommend you do the same. As mentioned above, when a 727 grenades it ain't pretty.
 
d55dave said:
The burnout issue happens when, in first gear (where the sprag or overrunning clutch holds the rear drum) the wheels suddenly grab......like burning out in the water box and letting the car roll out to the dry sticky pavement where the tires grab. This shocks the sprag clutch hard enough to damage it, tearing the outer race loose. Most manual valve bodies also apply the rear band in first to help prevent this. This is why a bolt in sprag (much stronger) is a must in a performance build.

A damaged sprag will allow the forward drum to spin up to two or three times engine rpm on your next hard launch or burnout in first. The stock forward drum explodes like a grenade somewhere around eight or ten thousand rpm.
Click to expand...


Exactly what he said. I had 2 that this happened to. Lesson learned. Thanks d55Dave for explaining it.
 
It worked good after i got it going again. i will check adjustment . am going to tear it down and check it over the winter. thanks Tim.
 
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