rear end rotation - 460 Ford Forum
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post #1 of 12 (permalink) Old 07-29-2013, 06:16 AM Thread Starter
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rear end rotation

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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post #2 of 12 (permalink) Old 07-29-2013, 08:55 AM
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How do you know the rear end rotated a whole 30 degrees? Was it stuck in that position when it was all over?
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post #3 of 12 (permalink) Old 07-29-2013, 11:05 AM Thread Starter
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Yes
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post #4 of 12 (permalink) Old 07-29-2013, 11:13 AM
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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.
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post #5 of 12 (permalink) Old 07-29-2013, 03:23 PM Thread Starter
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about 1/2 on the on the bars.....I was thinking of a snubber but it would have to be about 6" long......anyone weld the u-bolts to the housing?
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post #6 of 12 (permalink) Old 07-29-2013, 11:19 PM
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about 1/2 on the on the bars.....I was thinking of a snubber but it would have to be about 6" long......anyone weld the u-bolts to the housing?
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.
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post #7 of 12 (permalink) Old 07-30-2013, 08:06 AM
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I know we have a suspension shop near me that cuts, bends and threads u-bolts to whatever size you need. It is cheap to. I had some made for my old truck and I think it was $35 bucks for all 4 of them. Rob is right. No welding them. It just makes the metal soft and weak.
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post #8 of 12 (permalink) Old 08-20-2013, 06:02 AM Thread Starter
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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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post #9 of 12 (permalink) Old 08-21-2013, 06:11 AM
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As mentioned , check those spring perches , good chance the ends are rolled up
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post #10 of 12 (permalink) Old 08-21-2013, 04:28 PM
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As mentioned , check those spring perches , good chance the ends are rolled up
not a good chance , they are rolled up.

OP get the perches repaired/replaced, then have them boxed, welding required

Last edited by 2slow; 08-21-2013 at 04:31 PM.
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post #11 of 12 (permalink) Old 08-21-2013, 04:33 PM
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When I lifted my Mazda Navajo some years back I picked up a pair of really heavy perches from Rhino (iirc) There's lots of places that have heavier ones.
Rob

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post #12 of 12 (permalink) Old 08-21-2013, 04:36 PM
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Quote:
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I know we have a suspension shop near me that cuts, bends and threads u-bolts to whatever size you need. It is cheap to. I had some made for my old truck and I think it was $35 bucks for all 4 of them. Rob is right. No welding them. It just makes the metal soft and weak.
welding makes them soft and weaker !!!!!!!!

your car build with super glue or duct tape?
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