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Sheared Driveshaft

4K views 45 replies 8 participants last post by  Redtruck-VA 
#1 ·
Hey all, I have a 3rd Gen 1500 hemi mildly supercharged pushing ~500hp. Have probably 20 passes down the strip with it. Just had my stock rear driveshaft shear in half right down the middle @ 90 mph (4000 ish shaft rpm). What a mess, just crossing my fingers my tranny made it out okay. Trying to figure out what went wrong as it seems like a rare failure after talking around. Little nervous to take it out again, albeit next time will be with a built driveshaft. Since it didn’t fail in a dig from a dead stop I don’t think it was over torqued. I recently lowered the truck, which messed up my driveshaft angles. The best setup I could settle on had the tranny lifted to 3 degree down and diff at 0.5 degree up. So they are slightly out of sync at rest but this was all I could achieve to get some sort of negative working angle on the rear pinion to account for axle wrap. The truck didn’t vibrate at speed, but perhaps this mismatch still caused my failure? Did I overspin the stock shaft? Or just too much power?? Doesn’t seem like upgraded driveshafts are a hot topic in the ram performance world so any insight would be appreciated.
 
#7 ·
What type of traction control are you using. The stock springs have a lot of wrap and can really mess up both the angles and spring load making it misaligned.
 
#8 ·
Stock shaft, crushed the bearings (1310) in the cups. First high performance aluminum shaft 1350 joints, bulged the slip yoke which was an aluminum Sonnex. Second high performance aluminum shaft I'm using a 1350 steel viper slip yoke. I don't expect any issues with it using 60" truckarm suspension that does a great job of maintaing alignment.
 
#16 · (Edited)
Just seems like a drive shaft alignment issue to me. Maybe too much axle rap.

I setup my 03 to be aligned under WOT under boost. Using Caltracs for traction bars. With the load bar removed and cut down ranger leaf springs to prevent too much axle wrap. Had to do allot testing and tuning of the Caltracs to get them to work the way I wanted them to work for the way the power & torque came into the 03. Did have to add a little weight to the rear(tow hitch). Then it was working good. Did spin a little sometimes but, it did have a nice hook when it did get traction.
https://www.youtube.com/watch?v=RQ72xXx5dck


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#13 ·
Jeffhs66 welcome to the forum. Keith traded his vortech v7-ysi for a turbo a while back.. i'm running the same sc using a cog drive.
 
#17 ·
Running a Novi 1000 custom mounted with a 4th Gen Cummins intercooler and methanol injection. But ya I have no weight to the rear end, no spare tire no hitch just a roll pan. I’ll have to look into caltracs. How much axle wrap would be expected on stock springs and a flip kit?
 

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#20 ·
The bars do a great job. The leaf springs on ther own simply don't hold the alignment very well. Also flip kits need to be welded IMO.
 
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#21 ·
.5 up ? you want/need to be at least 5 deg down on the pinion with leaf springs
 
#22 ·
I've forgotten the degree's, but at max traction wot the pinion should be level pointing parrellel toward the trans output shaft. In other words both pinion and trans output shaft should be parrellel to one another at wot. Mine is not only parrellel but very closely aligned almost on the same plane. The truckarm IMO is about as good as it can get. Each wheel can be preload to what is needed and the 60" arms attach just behind and below the front yoke. The shaft is 3-1/2" .125" aluminum with 1350 joints and steel viper yoke. This is built for tranbrake/1000hp.
 
#24 · (Edited)
With 4 link,ladder/truck arm if the pinion is at say 4 Degree down, in the static position, once the suspension is loaded with acceleration it's still @ 4 degrees, the advantage to those systems is once the suspension is under load it's not going to deflect anymore yes it will travel small amounts it hits bumps in the track but pinion angle won't change, to change the angle to suit the track you have to adjust bars, pre load, track bar.
Leaf springs , the big issue is the harder you hit it the more the front spring segment wants to turns it's self in to an S shape, you have the body pushing down on the front hanger bolt , gravity pushing the rear housing up into the body , right there you have two forces going in opposite direction, then you have the pinion trying to climb up the ring gear and the tires turning counter clock wise twisting against the pinions clock wise motion.
The spring wants to bend upward at the spring perch with axle motion which changes the pinion angle .
there's a good video on you-tube of a 69 F100 with stock rear springs and the pinion angel changes as much as 12 degrees in swing from 5 down to 7 above with acceleration and deacceleration...…...but leafs work better for carrying a load of wood/coal or thick chicks to the ball game

that being said , with the advances in how we approach leafs, people have put leaf spring cars n to the high 4s in the 1/8. and I can think of 2 or 3 GM1500s on leafs that run sub 9s in the 1/4
 
#25 ·
Flip kit is welded out on the upper and lower perches. not sure how you can get -5 degree pinion angle with how low my truck is. The transmission tail is raised up about as far as it goes and it’s still 3-4 degrees down. If I could get it horizontal than 5 degrees should be achievable at the rear. Guess I need to drop the front of the motor
 
#27 ·
I shimmed my trans up and ground down the grove where the bolts sit from the motor mounts to get a better angle. Some of the lowering kits come with a trans mount shim. I get to have all of this fun again on my 05 rc. :dance:

Everything will be shifted over to the 05 from the 03 at some point (except for the 03 pcm) and vice versa.... :D :brows:
 
#30 ·
#33 ·
That driveshft must look hugh umder the truck! Nicely done.. do you have any pictures?
 
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