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Remove Plastic/Nylon Injected Universal Joints from Aluminum Driveshaft ???

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6.1K views 24 replies 6 participants last post by  Ravalli Surfer  
#1 ·
2004 Trailblazer LS Ext with 4.2L

It appears this vehicle has the original universal joints that are needing to be replaced.

From everything I've gathered people use heat to remove the injected plastic/nylon that locks the universal joints into place.

But, the driveshaft on mine is Aluminum.

Am I wrong in thinking that taking a torch to it to get the plastic/nylon out is a bad idea or ???

I have a ball joint kit, can I just use it to snap the plastic/nylon bond ???
 
#2 ·
I always heat mine --- even a propane torch will work --- just wear goggles because when it blows out, it can come at you too fast to blink.

Pressing against that injected plastic with a u-joint press can mess up the ears of the shaft --- where the cups reside.

Those cups won't fall or press out very easily at all.

Mr. Smokewrench always works.
 
#4 ·
I always heat mine --- even a propane torch will work --- just wear goggles because when it blows out, it can come at you too fast to blink.

Pressing against that injected plastic with a u-joint press can mess up the ears of the shaft --- where the cups reside.

Those cups won't fall or press out very easily at all.

Mr. Smokewrench always works.
So, just to verify, you even heat up the Aluminum shaft to remove that plastic/nylon ???
Not sure why, but taking a torch to aluminum just doesn't seem to settle well with me - lol...
 
#9 ·
A rosebud is kinda overkill ... I have used the cutting head and just not hit the trigger --- but like I said --- a plumber's torch will more than suffice.

If you have a heat gun that dims the neighborhood when you turn it on --- then --- yeah sure --- that'd be big enuff.

Otherwise --- a heat gun might get it hot enough in 30 minutes or so.

NO -- I take that back --- don't bother with a heat gun.
 
#11 ·
Well,
A rosebud is kinda overkill ... I have used the cutting head and just not hit the trigger --- but like I said --- a plumber's torch will more than suffice.

If you have a heat gun that dims the neighborhood when you turn it on --- then --- yeah sure --- that's be big enuff.

Otherwise --- a heat gun might get it hot enough in 30 minutes or so.

NO -- I take that back --- don't bother with a heat gun.
You're not heating the whole driveshaft --- just the bearing cups --- concentrate the heat on the flat side of the cups.

Watch your eyes --- I really mean that!
Okie Dokie - heat it is and a little plumbers torch is all I have so I'm good there. And WARNING Will Robinson heeded - I will make sure to have my safety googles on and long sleeves.
 
#12 ·
Well,




Okie Dokie - heat it is and a little plumbers torch is all I have so I'm good there. And WARNING Will Robinson heeded - I will make sure to have my safety googles on and long sleeves.
Yeah -- the goggles for everybody and long sleeves for the Nancy-boys,.

A little molten plastic stuck to your arm and forehead for a few days is a badge pf honor! Wear it well and proudly!
 
#18 · (Edited)
I'm sorry I didn't see this earlier.

When replacing U-joints in an aluminum driveshaft, the U-joints are "special". That is, the steel U-joint caps have to be "coated" so they don't interact with the aluminum of the shaft to cause massive corrosion and weakening.

I put a U-joint in my '97 K2500 plow truck with an aluminum shaft. The only proper U-joint I could find locally was at OReillys, a Precision-brand Communist Chinese joint p/n 331C, and that final "C" means Coated, for use in aluminum shafts.

I don't expect that this would be the same part number joint you needed, but I sure hope you got a coated U-joint, or it needs to come back out.

What I wanted was a coated U-joint that was permanently-lubed (NO grease zerk) because the aluminum shaft is more bulky than a steel shaft; and it interferes with the grease zerk poking out of the side of the joint. I tried installing the joint "correctly" but the zerk hit the shaft. I had to turn the joint around so the zerk faced the iron yoke of the differential, so that there was clearance.

I pack the caps with high-quality grease, and I have no intention of actually using the zerk. And, of course, I orient the joint so that the hole for the grease zerk is under compression when driving forward.
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#20 ·
A propane torch is ok to use to heat up the knuckle. To do so, have the driveshaft set-up and ready to remove the caps when the plastic melts and/or begins to turn black and burn-off. Apply flame heat in a flame-on, flame-off method to gradually heat the area around the caps. If you're using an oxyacetylene torch, use the same method but move the flame faster as the flame temp is around 5000 F. Use this method and you'll still be below the tempering temp of the aluminum, which is what you will want.
When I do these, I have a pair of u-joint bearing cross surfaces set on top of the open jaws of a vise and ready to tap near the welded area closest to the u-joint.
 
#21 ·
That's pretty much how I did it. Dealing with the plastic and getting the universals out and in went pretty easy, easier than I thought it was going to go. Now, I guess I need to double check that I got the "coated" u-joints.

I could be wrong, but I don't ever remember any of the vehicles I've had in the past having an aluminum drive shaft. It's been a while, many moons even, since having a vehicle with rear wheel drive.
 
#24 ·
Says it's "compatible", but not that it's "coated".

I don't know what to tell you.
 
#25 ·
Any time there's dissimilar metals in close proximity to each other and something that operates as an electrolyte (salt, acid, baking soda) then dielectric current is created (ever get a piece of aluminum foil on a filling?) and corrosion is gonna happen.

"Coated" is maybe good to use - or not --- I have no reference point for this particular problem.