Greasable birfield CV joints done (1 Viewer)

[Kernal]

While I had my birfs out and before I swapped sides I decided to have a precision machine shop turn my old birfs into greasable birfs. From reading here on mud I realize this is a tad controversial topic with some mudders, but I figured I'd be the guinea pig on this one. The company that I found to do this makes high precision parts for everyone from orthopedic surgeons to parts for military aircraft. I discussed the possibility of weakening the shaft with the companys assistant manager who is an experienced machinist, he said in his opinion based on the size of the shaft, the small size of the hole, and the type of steel it would not. He also mentioned that it was relatively easy to drill the hole, that the shaft of these OEM birfs was soft. He said it took them two shop hours and charged me $80 (I think he gave me a break).

Here are the specs if anyone wants to duplicate this on their own:

A 6mm hole was drilled down the shaft exiting into the bottom of the bell using progressive lengths of High Speed (HS) steel drill bits starting with very short bits finishing up with an aircraft drill bit about 10 inches long. The hole as it exited into the bottom of the bell was then slightly chamfered. The hole at the splined end of the shaft had a counterbore drilled into it which was 7.5mm deep by 19mm in diameter. This was tapped so that a 1/8 NPT zerk could be fitted. The sunken counterbore allows the zerk to sit low enough for the stock size grease cap to be used, is large enough for a grease gun nozzle to fit down over the zerk for greasing, and allows a small socket to fit down to install the zerk itself.

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[OGBeno]

Nice job. I like this idea.....

 

[simps80]

Wow! that is a really good idea.
no more shove it in the knuckle inspection hole and see what happens.....

didn't know it was 'controversial' didn't know about it at all

 

[Cruiserdrew]

Nice job. I like this idea.....

Me too. You could keep birfs alive forever with a monthy shot of grease. Right into the palce it's needed as well.

The strength in something like that is mostly in the outside diameter-it would be highly informative to do pre and post destructive testing.

 

[Curran]

Awesome.
I think that this the first time I've seen someone actually try this.

 

[Shipwreck]

So who wants to be the Beta tester on a set of Longfields to find out if this would extend their lifespan on a daily driver?

 

[little_joe]

Very nice thinking and work! I'll be following along to see how these do over time, and hope for the best.

 

[harrydunn]

Pretty slick I must say...

 

[Kernal]

Earlier I considered shipping these off to a company in Connecticut that does precision gun drilling; gun drill bits are apparently less likely to "walk" off center, but cost about 10 times what an aircraft drill bit does and the shop needs some special equipment to pump coolant down the bore of the gun drill bit to cool it and wash away the metal that is drilled out. I had also talked to a machine shop in Canada that does this for their Landcruiser mine trucks using the aircraft (long) drill bits but they drill an even larger hole at 11mm. Decided to go with a ~6mm hole that is closer to what the company in Australia does for their greasable birfs. Like someone told me about my (slow) front axle job, it's not a nuclear reactor.

 

[d0ubledown]

nice..and under a hundred bucks to boot! definitely do some extensive testing and report back
i wouldnt think itd weaken the strength of the birf either. i mean usually when a birf goes, isnt it the cage of the bell...no? bobby long should get some of these made and test them...

 

[Kernal]

The main things I picked up from reading old posts on this was the concern of weakening the shaft and the chance of pumping too much grease into the knuckle which then could get forced by the axle seal into the axle housing. The company in Australia that sells these also sells a pop-off valve that opens at 2psi, it replaces the inspection/fill port square plug, but there are various pop off valves available here in the US that would fit, just haven't decided on which one yet. I think if I just add small amounts of grease to make up for the small loss of grease past the wipers I should be OK for now until I can get the correct pop-off valve, especially with the Marlin Seal that seem to fit very tightly to the axle shaft.

 

[jlg32281]

Post up the contact info of the shop that did the work for you.

 

[hntashdjian]

You should assemble the birf to the axle and pump some grease in there before you put them back on the car. This way you know how many pumps it takes for the cage area to get filled with grease.

When your ready to grease them lateron, just take the fill plug off and pump away.

 

[FirstToy]

nice!
contact info? maybe we can send a batch to keep him busy for a few days

 

[cme4lyt]

Sign me up !!!

I'm about to do this 'dreaded' job and I'd love to ship my birfs off for this work.

What about a 'group' buy ? I'd love to be the second... or third...... or forth guinea pig.

BTW, thanx for another great write up thread. Rgds...jonathan

 

[Ivan80]

I like this idea a lot. I'll definitely look into it when I do my next birf job. Thanks.

 

[Kernal]

Edit: the company that originally drilled out my birfs is no longer accepting work for automotive parts, apparently there was a change in management. However any machine shop that does precision work should be able to do this if you have one in your area, just show them the specs I posted. You could also show them the photos above or this diagram (see below) if they need a visual.

 

[TrickyT]

Great idea! I've never heard of a shaft breaking on a birf, it's pretty much always the bell housing or the cage. So I think any concerns about weakening the shaft are unfounded.

And you don't need to be injecting a ton of new grease all the time. Just a pump or two at each oil change should do wonders. And with this approach the new grease is getting added right where it's needed too!

If I can find a machine shop to do this for a reasonable price it will definitely go on my high-priority list of things to do.

 

[e9999]

been contemplating doing this for a while but I assumed it would cost much more than what you paid so didn't proceed. My mistake.

I would definitely put a relief valve in the inspection port. Otherwise you're gonna change your diff oil a lot. Remember a little hand grease gun can probably give you easily several hundreds of psi.

Anybody out here good with Solidworks? Would be great to have some detailed drawings to take to a shop for an estimate.

 

[rhyary]

Not sure you will need a safety valve.
What if you just open the square plug before pumping grease, and just stop when grease comes out the top?