Front Drive Shaft Update

[Dokatd]

The path that I really wish someone would go down is designing or finding a better high speed Rzeppa boot. It isn't the joint that mechanically fails but rather the boot rips and spills the grease and then the joint fails from lack of lubrication or contamination or both. Here is a boot that certainly appears to be able to handle a more acute angle than the factory one.

High Speed CV Joint Boot Retainer 4.236" Diameter

Retainer only. High Speed CV Joint Boot Retainer 4.236" Diameter

makodriveshafts.com

View attachment 7895374

Sure seems like a new design should be easy. But keep in mind this has been a problem for over a decade in Jeeps and some other vehicles. It's just that Jeep era just slapped in an $800 custom shaft and forgot about the problem.

 

[Tenac]

Ugh, I lost a long explanation of this and don't have the energy to retype. But, your stock Rzeppa shaft is good until the grease boot fails. The 3° deal is in regards to the proposed design from Agile. Their shaft simply exceeds the continuous operating limit by a fair bit. Not saying it won't work, it may or may not cause vibrations and may or may not fail in 20k miles or less. But your boot MAY fail in the same time frame. The new aftermarket Terra joints have been reliable so far with only one public report of a boot failure.

Thanks for clearing that up for me, it is hard to keep up with all the info for sure on my end. So I'm good OEM until the boot fails then I should pucker up lol. For me if I lift means I need to replace joints to stop vibration every say 15k miles so be it, gotta pay to play. lol I just don't want it to grenade itself if possible.

 

[Dokatd]

Thanks for clearing that up for me, it is hard to keep up with all the info for sure on my end. So I'm good OEM until the boot fails then I should pucker up lol. For me if I lift means I need to replace joints to stop vibration every say 15k miles so be it, gotta pay to play. lol I just don't want it to grenade itself if possible.

No worries. Luckily a failed boot does not mean instant disaster. From that point it's just a slow progression of failure.

If you are just tooling around town or even off-road you may find the joint will be largely ok. It's doing 85mph down the highway that eats it up. At that point you should start to notice a light grinding sound. Nothing ominous, just a different sound that you haven't really noticed before. It will eventually get loud enough and clunky enough that you can ignore it and you will have at that point deduced that your boot has failed. This will happen over many hundreds of miles. At this point the joint may go on for another thousand or more miles depending on conditions and speed. And finally if you persist in neglecting the noise the shaft will eventually chew itself up enough to separate at the T-case and largely fall limp on the ground as it spins. The likely hood of massive flailing about is moderately low for a Rzeppa joint. A single Cardan or even worse a double Cardan can get to flailing about pretty bad and they tend to tear s$&t up in short order.

So yeah, take you pick of the poison at this point, but I suspect the Terra Rzeppas will do 10-15k before failure of the boot. Maybe much more if you drive 60mph or less most of the time. It's the heat of higher RPM that's getting them if not a pinch in the boot from lifting the truck without tending to the shaft first.

 

[Dokatd]

Y'all don't take my word for it, research for yourself. This image shows the angle or slope of the front drive shaft on a 2" lifted Gren. The angle gauge was zeroed out on the pinion. So that means you have 13.2° at the pinion flange. The engine and trans is tilted in the truck a few degrees which makes the angle at the transfer case about 15° give or take. Our drive shafts are turning at about what, 3,500-4,000rpm at 80mph if I did my math right.

 

[Commodore]

View attachment 7895493Y'all don't take my word for it, research for yourself. This image shows the angle or slope of the front drive shaft on a 2" lifted Gren. The angle gauge was zeroed out on the pinion. So that means you have 13.2° at the pinion flange. The engine and trans is tilted in the truck a few degrees which makes the angle at the transfer case about 15° give or take. Our drive shafts are turning at about what, 3,500-4,000rpm at 80mph if I did my math right.

I wish I know what they didn't tilt the pinon up 5 degrees from the factory. It would have made a huge difference.

 

[TCMColorado]

View attachment 7895493Y'all don't take my word for it, research for yourself. This image shows the angle or slope of the front drive shaft on a 2" lifted Gren. The angle gauge was zeroed out on the pinion. So that means you have 13.2° at the pinion flange. The engine and trans is tilted in the truck a few degrees which makes the angle at the transfer case about 15° give or take. Our drive shafts are turning at about what, 3,500-4,000rpm at 80mph if I did my math right.

Longevity withstanding, the new shaft from Agile is problematic simply because the angle at each end of a single cardan shaft has to be nearly equal for it to run smoothly. Based on these measurements the difference is ~1.8° which will definitely cause vibrations somewhere in the RPM band.