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rear end rotation

2K views 11 replies 5 participants last post by  2slow 
#1 ·
I've got a 66 fairlane with a 30 over 460 mild hopped up. c-6 with a 2500 stall.9" Detroit locker.slapper bars. I usually just give it a blast after i'm roiiing and it will spin the tires a long ways but goes down the street nice(this is street car only). yesterday I tried a flash the converter from a stop just to see how it felt......the whole car liffed dug in and then bang.....ends up the rear end rotated up about 30 degrees and broke a rear universal u bolt...I don't know which caused which cause which...the u bolt breaking or the rear end rotating and braking the u bolt. I thought the slapper bars would limit the rotation of the rear end. sure don't want to do it again(car is back togeather) is there more I should do...weld the u bolts that hold the springs and housing so the entire housing can't rotate......or maybe long traction bars....the engine makes a lot of torque....any ideas? thanks
 

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#4 ·
It kind of sounds like your slapper bars were too far away from the end of the leaf spring to begin with. Either that or something else just twised & broke. What kind of a gap is between the end of the slapper bar & leaf spring now? This may also be a case where you have too much power and you need a pinion snubber to go along with the slapper bars to keep the rear end lined up properly.
 
#6 ·
Nope, not a good idea, you will anneal them then they will be soft.It sounds to me like the u bolts streatched over a period of time and allowed the diff to start moving. Have you checked the spring pearches for flatness and alignment with each other? Leaf springs go through some violent movements in several different directions at once when you start feeding them gobs of power and add a sticky tire. Worse case scenerio is you'll need some beefier spring pearches and larger diameter U bolts and a preventative maintenance program. :)
Rob
 
#8 ·
up grade

going to replace the old 7/16 u-bolts with new 1/2 u-bolts....taking out the 4:11 Detroit locker and putting in a 3:50 posi. this a pure street/h'way car. the car pulls great from idle to 6k but runs 3k at 65mph. I wanted to take some h'way rpm out ...so 3:50 should work well.

thanks for the help
 
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