blew my u-joint out

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1969dodgedartgt

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well, you may or may not know that about a year ago I found a missing bolt in the flange holding my u-joint to the rear axial, and I ended up doing a helicoil to attach it. Well last night I blew out my u-joint shortly after discovering the buckets of torque my hard has at about 3000 rpm in first gear. luckly I was stationary when this happened.

I had just put some seafoam in my gas and crankcase trying to fix a lifter tick. I wanted to test my power with a peel out as i'm fond of doing. When I stomped on the gas, all I got was a loud bang followed by some nasty rattling and clanging. I had visions of my pistons coming out my engine or some such terrible thing. I was actually pleased to see it was just my u-joint.

Do you guys think I caused this with my helicoil? Also I need a new flange, anyone know where I can get one for my 7.25 rear?
 

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i am going to scrap my 7.25 if you can't find one send me a message and its yours
 
Jamakin said:
i am going to scrap my 7.25 if you can't find one send me a message and its yours
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Thank you Jamakin! I'll do a little searching and message you if I'm not successful.


mmm i found this

now i just need to meditation on price and potential whole rear upgrade
 
if your looking for more then a quick fix i would ditch the the whole rear and go with something stronger. Those 7 1/4s are a ticking time bomb or maybe just get it on the road again and work on getting all the parts together
 
Those peel outs will do it every time.
 
1969dodgedartgt said:
Thank you Jamakin! I'll do a little searching and message you if I'm not successful.


mmm i found this

now i just need to meditation on price and potential whole rear upgrade
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I wouldn't pay that price for one. If you're thinking of upgrading the rear, just scarf up a decent used one and pop it on there for now.
 
looks like it was the helicoil. Just put a new flange on for now and save up for something bigger and better. maybe you can even swap it in over the winter.

Your going to want to mark the threads and nut and count the turns to get the nut off when you change the flange. otherwise you could crush the sleeve too much causing too much bearing preload.
 
I also just pulled the 7.25 out of my Dart the other day. So if you need a piece you can PM me also, no charge.
 
You should be getting your parts any day now. Late last week, I will send you the tracking number when I find where I put the slip :(
 
That 7 1/4 rear is not so strong to start with so any drilling for hellicoils is not going to help it stay together if you plan on making any tire smoke. If you replace the yoke, that rear/yoke/u-joint will still be a weak link. Its no big deal to blow up 7 1/4 rears but there is always a chance of destroying other parts of your drive line when you eventually take out that rear. Start looking for an 8 3/4 or even an 8 1/4.

I show this picture every time one of these threads come up about drive lines being strong enough. Here is the result of a broken 7290 u-joint (8 3/4 rear). The transmission tailhousing was broken in 2, the tail shaft was bent more than 1/4", yoke bent, and my fancy new heavy duty drive shaft looked like a banana. It was a very costly and time consuming repair for a $30 u-joint failure. The lesson here is not to do anything to weaken that drive line! If anything is going to break loose, make sure its your tires against the pavement.
 

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I blew out my front U joint at the strip. The 727 almost had the same fate.
I cracked it about 2/3 of the way around. Was able to get it welded up.
I'm glad I had a safety loop on it.
 
omg its been over a month of thinking, working on work (taking public trans/bike/gf car), doing nothing, trying various things. I bought a compressor and impact wrench last week and a torch today to try and get that dam big bolt off from the flange. I just got it off after a couple attempts with heat and letting penetrating oil sink in.

Now I dont know how to get the rest of the flange off. Heres what I'm looking at, do I need a tool to grab those teeth and turn the flange? service manual is no help. also is all the oil gona come out when I take that flange off?

maybe I just need to bang on it with a hammer, gona try that now :)
 

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ok, nm got it

omg, my car is together again. I' didnt replace the ujoint though. I could not figure how to take the old one off the shaft, tried removing the clips and all but nothing.... I just threw some more grease in the old one and put two new caps on.

How worrried do you think I should be about this ujoint. I'm scared of it. I want to get the whole drive shaft and rear axil replaced with a 8-3/4 ASAP. I'm about to go for a slow test drive. I didnt do any angle measuring as the fsm shows.... I'm not at all sure I fixed this correctly, but it looks good and solid so I'll give it a small ride....

If you think I'm in danger please yell :):sign3:
 

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I hope i don't sound like a jerk here but, if you could not get a u joint out did you get the pinion flange back in the ballpark of the correct inch pound preload? a lot of guys mark them and count the turns to do a quickie fix. I just think changing a U joint is easier than replacing that pinion flange. If you hear any odd noise stop driving it. I don't mean to be an asshole. maybe you put the pinon flange in perfectly but the u joint was super rusted in there or something?

Other than that the U joint may have been okay since the straps broke. if it was me i would have went with a completely new one though. Its cheap insurance.
 
1969dodgedartgt said:
ok, nm got it

omg, my car is together again. I' didnt replace the ujoint though. I could not figure how to take the old one off the shaft, tried removing the clips and all but nothing.... I just threw some more grease in the old one and put two new caps on.

How worrried do you think I should be about this ujoint. I'm scared of it. I want to get the whole drive shaft and rear axil replaced with a 8-3/4 ASAP. I'm about to go for a slow test drive. I didnt do any angle measuring as the fsm shows.... I'm not at all sure I fixed this correctly, but it looks good and solid so I'll give it a small ride....

If you think I'm in danger please yell :):sign3:
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From looking at your picture the cap on the drive shaft is about 1/3 of the way out of the hole. You should look it over again. I went back and looked at your original pictures and they were that way then also. Could that cause a balancing issue that is causing your problems with the yoke?
 
Do not even move the car out of the driveway.
That joint does not have the inner clip to hold the U-joint cap in place.
Pull the drive shaft, buy a new U-joint and take it to a shop which can replace the entire u-joint correctly.
If that drive shaft comes out on the highway (which it will come out) and kills somebody you could be looking at involentary manslaughter or worse.
 
A friend ... used to remove them by putting the joint caps back on and squeezing in a vice and then pumping grease in to push out the caps in the shaft itself...worked everytime....make sure clips are removed though:D...I would definetly not drive with that u joint....I would guess its integrity is already compromised after hitting the ground and the one cap poking that far out is dangerous...better safe than sorry...
 
mmmm thanks for yelling guys....
I have driven it, no noise. I have driven it very very fast, and thrown a lot of torque at it even. I still worry about it and (will find a place to take it to), my rear axle is leaking a bit after the work I did anyway. I just spent a lot of money getting my 4brl put on, rocker arms cleaned and exhaust leak fixed, so am very very hesitant to spend more money. Maybe I can just get one of those safety straps to hold the shaft if the joint breaks.... I will avoid driving, but must drive it (slowly) home from a shop today. Not going to pay that shop anymore money.

The clips are in place..
the correct preload, i'm completely uncertain of. I was told to count the turns when it came off, but the nut came off quickly and unexpectedly so I could not count.
I've had people say the unjoint looks funny with that cap out that far before, but thats the way it originally was, its like that on both sides, so hopefully balanced.
bolts came with yoke, they dont look to be grade 8


oh more money for me car ... :(


F#*@ that, I'm gona drive. I'll go try and find a safety strap... I feel semi confident after what it has withstood since the operation. I will give it another look. I'll take it in when I feel I can afford, in meantime I'll try and be faithful.
 
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