Rear Tires Suddenly Lock Up Going 65

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I'm tryin' ta tell ya---BRAKES are NOT the problem here, unless it's a "loose hardware" issue, and that will be easy to spot--just yank the rear drums
 
I have heard of the spider shaft slipping out of place ( the keeper bolt was broken) and locking up on the case then sliding back when the car was backed up but that was at a lower speed. At 65 I'd think it would break the shaft or split the housing.
 
That cant be a great feeling of the wheels locking up at 65 mph with a tin foil hat on my head. lol
 
The most likely cause, IMO is the ring and pinion malfunction as described earlier. My guess is that this is a 489 case 8.750 rear. I bet dollars to doughnuts that the crush sleeve was put under stress and crushed too much resulting in incorrect pinion angle and causing the lockdown. It's not too uncommon. That's the weak link in the 489 case. I would get a crush sleeve eliminator anyway (assuming again it's a 489) and replace the crush sleeve. It will make the rear much stronger and you'll never have to worry about it again.
 
That could be easily diagnosed by grabbing the driveline near the rear yoke and see if it moves laterally at all.
If the rear yoke moves even a little bit that's probably what it is.

StrokerScamp said:
The most likely cause, IMO is the ring and pinion malfunction as described earlier. My guess is that this is a 489 case 8.750 rear. I bet dollars to doughnuts that the crush sleeve was put under stress and crushed too much resulting in incorrect pinion angle and causing the lockdown. It's not too uncommon. That's the weak link in the 489 case. I would get a crush sleeve eliminator anyway (assuming again it's a 489) and replace the crush sleeve. It will make the rear much stronger and you'll never have to worry about it again.
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This is why this is a great sight, everybody making personal contributions from their own personal experiences in life. Can't wait to see the final conclusion.
 
Some of these outcomes are pretty intersting as long as they post the causes and end results.
Otherwise it's all a big question mark.
It'd be interesting to have a paypal account that a person/we placed a bet with on the actual end solution and pay the correct poster the pot.

Example, Someone says it's the intake manifold a puts 5 bucks on it.
64 people vote with cash and there's 320 bucks.
Whoever gets the answer right gets 320 bucks.
If no one does it goes to the house (FABO)

Hmm


64conv65hard said:
This is why this is a great sight, everybody making personal contributions from their own personal experiences in life. Can't wait to see the final conclusion.
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I don't believe a hydraulic issue is the problem either. Nor do I believe something in the valve body could suddenly do that. Sounds to me like a mechanical issue and I wouldn't be one bit surprised if it is something in the rearend although what Kim mentioned about the output shaft support freezing up is also possible but generally if something like that swells up and sticks it doesn't release and work fine afterwards. For it to lock the wheels so violently that it skidded to a stop it has to be a mechanical issue. I have personally had brake lines go bad that locked the wheel up but it never did it on it's own. When I stepped on the brakes it didn't release and even then it never skidded to a stop. I have also had a master cylinder problem where it didn't release when you let off the brakes but again it only happened when I stepped on the brake that it didn't release. You said you didn't touch the brakes when it happened so how could that possibly be the cause? Hydraulic pressure doesn't just happen. It's the result of you stepping on the brake pedal that pushes the m/cyl. piston in to create the hydraulic pressure.

First thing I'd do is jack the car up and crawl under and check the rearend to see if the pinion has slop in it.
 
This happened to me in my 78 camaro a couple years back. a small piece of my brake pad broke off and wedged itself causeing both rear tires to lock up.(I had drums in the back). Once i put the car in reverse the broken piece unlodged itself and i went on my way. When i pulled off the drum the chip just fell out.
 
I did put it in neutral after I came to a stop. I didn't shift into any other gear or neutral while the tires were locked. It all happened so fast that focus was more on controlling the car and safely stopping it.

I'll defiantly keep everyone updated with pictures of the outcome. I'm going to start at the tires and work up the drivetrain from there. Probably gonna yank the axle shafts and pull the third member for a full inspection, I'd like to know the condition of the suregrip anyways. Anything special I need to know about pulling the shafts and third member before I start? Any funny measurements I should take? I have a dial indicator, but not a service manual. If the weather is nice I will start looking things over tomorrow.
 
Ok well this has been buggin me so i asked my dad he knows more then me lol he said that my brake line should not lock them up like that .. he would look at the third member 1st sorry i was going off whats happend to me man keep up posted .. i will keep asking lol
 
Oklacarcollecto said:
That is a very very good idea. I had a front hose do that and lock a caliper down.
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Me too! Ferrari F40 of all cars...big Bosses collection of exotica, we (collection custodian and I) would hot lap them every 6 months to keep them running. On the way in from around a large city block, the left front tire locked up and we had to drag that tire in about 150 yards to the shop. Flat spotted a perfectly good OEM Pirelli P6 (?) although they were all about 15 years old. Only had about 3000 miles on them. Oh well, only his money. We cut the hose with a band saw and it was totally closed up, MC pressure would overcome the swelling, but not the caliper return pressure. Like a one way valve. Cant explain how yours "healed"..I though one style of TF did have an issue with the band overrunning the strut.
 
Well despite the cold weather I took the tires off to find nothing wrong with the brakes except all the shoes had cracks but no loose hardware, nothing. Pull the driveshaft, pinion seems to have zero lateral play. Pull the axles, pull the center section, no broken teeth, no cracks, no missing parts or hardware, no fresh scars, spins nice, no binding, pinion nut is tight. Teeth seem to be broken in nice and seen some miles but nothing crazy. With the sure grip it's hard to see the spider gears but everything seems to be in the right place and undamaged. I guess it's something in the tranny.. Still confused on how it happened though.

The sure grip is a cone type and the axle is a 489 unit if that changes anything to the diagnosis of rear end or tranny
 
Take a look at the rubber hose going to the rear brakes. If a partial collapse happens, the brake fluid is not getting back to MC as quick and the rear brakes will be partially "on". Doesn't take long and at 65 the shoes will warm up and grab the drum (not sure how tight you have your rear brakes adjusted). When you pull rear brakes everything will look fine. Try jacking up rear axle, put stands under axle and block front wheels. Put in gear and apply and release brakes while giving little gas (you cannot spin wheels by hand fast enough to generate enough friction (heat). See if this will cause brakes to slowly apply.
 
Of course! Still could be a collapsed hose, that actually makes a lot of sense now. Would also explain the lack of power feeling just before they locked up. I may have enough power to not even notice a dragging brake until it heats up and really starts to drag. I was going to do a brake job while I'm at it since they're in bad condition, probably just change the hose for good measure, flush the brake fluid, machine the drums, new quality shoes. But I'll wait on that and experiment with everything the way it is now to try and replicate the problem. Also, the drums were "ok" coming off but nothing seriously tight.
 
Transmissions have a function built into them where when you let off the throttle they will use engine compression to slow the car somewhat. Much of this is dependant upon year make model type of trans, etc. Hard to believe if this is what malfunctioned that it is now fine, and didn't tear itself to pieces. Call me stubborn, but I still think this car went into reverse. When you fool around long enough with the shifter in a way that it really wasn't meant to be used, eventually the law of averages will kick in and something bad will happen. I don't know how hard you are getting on this car shifting like that, but maybe the motor mount broke and you didn't notice it because you were too busy trying not to go thru the windshield.
 
Once everything cools down, the brakes won't be grabbing anymore. like during the time that passed when you were cleaning your shorts after the lockup (sorry, just had to). I work on trains and when working on loco's or train cars all it takes is a dragging brake on a wheel to keep you from moving them in the shop. same thing happens, shoes warm up and then stop the loco. we will have moved loco 75 yards then it doesn't want to move anymore.
 
A short note about how my brakes locked up. About 1 1/2 to 2 years ago my right front caliper felt a little funny like it was dragging just a little. Since it was fairly new I felt that it was the flex line so I bought one. It sat on top of my tool box untill just this summer when I had to finally change it when the brake completely locked up while I was trying to pull my boat up the ramp. After the pressure bled off I was able to get home without using the brakes, since I am in the country. Point is I had plenty of warning about this condition. Others have mentioned that they also had this type of problem, and I bet some of them knew it before it became totally critical. What is hard to understand is why it didn't happen again, right away. You can check for a hot brake by putting the back of your hand near the wheel and feeling the heat. Don't know if you did that after your panic stop, but it could have told you a lot. One other thing, what does your trans fluid look and smell like? Also, although it is not by any means impossible, it would take a lot of fluid to be trapped to activate two wheel cylinders. A caliper requires much less. The brakes must be almost perfect because usually one could be expected to apply sooner than the other. I don't know if this is true or not, but with a sure grip maybe one locked wheel could stop the other. I don't know, I never tried to find out. A differential guru on here could probalby tell us.
 
I still think its something in the trany. Most likely you will have to totally disassemble to find the problem.
I think that to lock the tires up with the brakes you would have to apply them hard and fast. My duster has 10x2.5 rear drums and optimisticlly 300hp. I can easly out power the rear brakes. You have ruled out the rear end that leaves the trany.
 
I'm also Still going with the Tranny. especially factoring in the manual shifting aspect when it happened.
I just hope it ends up not costing a fortune to fix.
 
Hmm..hopefully it's the brakes. As fun as a tranny rebuild sounds (I wanna do some motor work and paint over the winter anyways) I don't need another project. I don't understand how manually shifting plays into this. I can assure everyone that it did not accidently get thrown into reverse. I've heard rumors of it being bad on a tranny but never really understood why. Makes more heat, uses different bands and clutches..? I sometimes manually shift cause..well...it's funner that way and I can offer more control through turns or when passing. I don't see how the tranny could have taken this kind of abuse and still shift ok, manually and automatically.
 
Hopefully it's the brakes X2. Sure would be a cheaper and easier fix. But again, just my opinion. BTW, just ask my wife, I've been wrong before also.
 
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