DRIVESHAFT FAILED! READ THIS!!!
#41
08-10-2007, 03:35 PM
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RE: DRIVESHAFT FAILED! READ THIS!!!
You crack me up Eltupac. Not to hijack this thread anymore than I already have but the 4.10's in my old truck kept the rpm's up way too high at 70 mph and up killing my mpg. Granted it was a diesel and probably would not be as big an issuse with a free revving gasser but I think that that gear ratio would really hamper the 3.7L with even worse gas milage than it gets already. Pm me if I can answer anymore.
#43
02-27-2008, 10:06 AM
RE: DRIVESHAFT FAILED! READ THIS!!!
ORIGINAL: stump_breaker
The only thing the 4:56 gears do is increase the critical speed of the driveshaft which is what got me started on the research I have been doing. Problem is when I contacted Dodge about the tested critical speed of the shaft from Spicer, I was told this was propritary information or information that was otherwise unavailable and they suggested buying the FSM. So, I did and there is no info on the driveshaft. I contacted a specialized driveshaft manufacturer in Dallas that builds them for big trucks. After giving him the information I could get on my shaft, he said with the 4:56 gears I was approaching my critical speed if I approached xxxx rpm's which was somewhere around 80-85 mph (give or take) although my vibrations started at 78 mph. After doing the math, I just assumed I could hold off on replacing the shaft for a little whileand just keep it about 70 - 75. Obviously I was wrong.
My buddies 03 2500 has a very thickwalled steel shaft but he also has the diesel which does not approach the rpm's we approach in our gas trucks. At 70", a steel shaft would warp at the RPM's we approach.
Driveshaft rpm math is final drive gear/engine rpm's. In my case .67/2500 rpm's at 70 mph = driveshaft RPM's of 3731. Weassumed the critical speed somewhere around 4000-4100 but we could not get difinative answer from Dodge on the thickness of aluminum used which playes a large part in the critical speed of the shaft. This is also whay they put speed limiters on these trucks. The limiter is set to keep the shaft from hitting it's critical speed.
I'm having an issue with BitPim trying to get the pics off my phone - of course.....
I knew the shaft was cheaply made but I could not believe what I saw. I'm still working on the pics.
The only thing the 4:56 gears do is increase the critical speed of the driveshaft which is what got me started on the research I have been doing. Problem is when I contacted Dodge about the tested critical speed of the shaft from Spicer, I was told this was propritary information or information that was otherwise unavailable and they suggested buying the FSM. So, I did and there is no info on the driveshaft. I contacted a specialized driveshaft manufacturer in Dallas that builds them for big trucks. After giving him the information I could get on my shaft, he said with the 4:56 gears I was approaching my critical speed if I approached xxxx rpm's which was somewhere around 80-85 mph (give or take) although my vibrations started at 78 mph. After doing the math, I just assumed I could hold off on replacing the shaft for a little whileand just keep it about 70 - 75. Obviously I was wrong.
My buddies 03 2500 has a very thickwalled steel shaft but he also has the diesel which does not approach the rpm's we approach in our gas trucks. At 70", a steel shaft would warp at the RPM's we approach.
Driveshaft rpm math is final drive gear/engine rpm's. In my case .67/2500 rpm's at 70 mph = driveshaft RPM's of 3731. Weassumed the critical speed somewhere around 4000-4100 but we could not get difinative answer from Dodge on the thickness of aluminum used which playes a large part in the critical speed of the shaft. This is also whay they put speed limiters on these trucks. The limiter is set to keep the shaft from hitting it's critical speed.
I'm having an issue with BitPim trying to get the pics off my phone - of course.....
I knew the shaft was cheaply made but I could not believe what I saw. I'm still working on the pics.
Thanks in advance
#44
02-27-2008, 11:00 AM
RE: DRIVESHAFT FAILED! READ THIS!!!
Wheres parts/service when ya need him.
Well most people that are going to 4.56 is because of a much bigger tire, and that's generally a 4x4 guy with the split shaft, seeing that putting tall muds on a 4x2 makes as much sense a taking a ***** to dinner, youre still gonna get f#^ked in the end.
#45
02-27-2008, 11:39 AM
DC Insider
RE: DRIVESHAFT FAILED! READ THIS!!!
yeah i had this same problem happen on my truck when i goin down I-94 here in michigan bout 80MPH (back in October 2007)...the dealership it got towed to wouldn't replace it under warranty because they said "the lowering kit and air bags in the rear made the driveshaft fail"...needless to say, i called the warranty dept and got my money back because the driveshafts have known issues....so anyone with an aluminum driveshaft, just watch yourself and if you start to feel a vibration get it to the dealership and have it replaced...i just have a drivehsaft made for my truck, 100% steel and it cost me like $150...least shouldn't have to worry bout this crap again
#46
02-27-2008, 02:51 PM
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#47
05-13-2008, 11:08 PM
RE: DRIVESHAFT FAILED! READ THIS!!!
Our 08' PowerWagon has steel shafts front and rear. When you tap on them with metal they "sound" much thicker/different than our 04' 2500 Ram which also had a Hemi and 4x4. U-joints had to be replaced at 24000 miles in rear shaft on that one. I'm sorry but they should last longer than that with no swampin'. We have the 6-speed manual and 4.56 & at 80 it turns 3000-3200 rpm so the driveshafts must be screaming in our powerwagon. No vibration-smooth.
