CV Joint "Blues"

[Christopher Schimke]

[Jon_slider]

[Syncro Jael]

It is just interesting to hear all the comments about CV joints. Some say polish, some say no, this grease, that grease, to much angle, to expensive, to cheap, this brand, that brand, do this, don't do that. I am used to just getting a good quality part, quality grease, install it correctly, then forget about it until time for maintenance.

I just thought I would try what some others have done. I only polished the high marks out. There were still some machine marks in the races. I just could not install CV joints that would hardly even plunge. The earlier joints that I purchased were not this stiff out of the box.

As far as the temperature of the CV joints I just took a reading on what was under the van at the time. The Autozone half shaft was on there and had enough miles to wear in. But it was also on the side that has been running hotter.

Last night when I took readings again, it was with all new Lobros (Polished) and the temps were within a couple degrees on the inners on both sides.

I do appreciate the knowledge and wisdom from all of you and your thoughts and comments. Hopefully my CV joint issues will subside for a while.
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1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat)

[Jon_slider]

[MarkWard]

All of this is very interesting, but reputable replacement CV joints should not require all of this extra attention. Certainly car racing has more unique challenges, but these joints should not require blue printing to push our shoeboxes down the road. Hopefully this will catch up with the manufacturers at some point.

As far as the grease is concerned. CV grease should contain called something like molybdenum. It is a graphite type additive that should adhere to the metal and act as an additional lubricant to the grease.

I am currently running 4 new Lobro CV joints that I packed with the grease supplied as a test. I have a trip to Wisconsin and back and a trip to Colorado and back on them. Now would be a good time to pull the CV's and inspect their wear. I just have too many other projects going on right now. I have always used Redline CV2 grease for CV's. These vanagon replacement CV's have been the headache.
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☮️

[Wildthings]

An alternative to polishing the new joints would be to have them shot peened. This should smooth them out a bit and get the work hardening started across the entire face of the joint.

[?Waldo?]

I can see how having a smoother surface would be very beneficial, allowing the joint to move and avoiding wearing the same points.

I can also see how having the bore very closely match the size of the balls would also be beneficial by increasing the contact area between the ball and the channel and reducing the contact area pressure.

[Jon_slider]

I just sent email to Weddle, will share what I learn.

Also see
http://www.weddleindustries.com/services/house-rem-superfinishing-process-weddle-industries

http://www.weddleindustries.com/services/shot-peening

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Subject:
Vanagon Syncro CV Joint Polishing

Dear Weddle,

In this thread
http://www.thesamba.com/vw/forum/viewtopic.php?p=7390169#7390169
we are discussing the high failure rate and high operating temperatures of currently offered Type 2 and Type 4 CV joints for Vanagons. Currently new CV Joints from companies including GKN Lobro are arriving very tight, and are developing pits within the break in period.

I see you offer polishing services including Shot Peening and also REM Superfinishing services.

What would it cost to purchase a set of 4 GKN Lobro CV joints, prepped by Weddle, so they plunge freely and operate smoothly, with whatever process you feel most appropriate?

Thanks!
---

I got the reply already!:

"We can shot peen the cages and REM the joint for about $60.00 each for a few of them. If you wanted to do a bunch of them, say 30 joints, I could do them for about $30 each. That would include shot peening the cages."

imo this is a product offering opportunity for anyone interested in stocking a bunch of CVs for resale.. you know,
"Blue Goat CV's"
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My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco

[IdahoDoug]

Just to clarify regarding temps of CVs on each side of the car. I haven't read what I posted earlier in this thread, but I would not expect to see temp differences from right to left due to one side simply being extended too far being readable with an IR gun. Rather I'd expect damage from the heat being generated at the wrong spot locally within the joint creating further damage, but the total heat of the CV joint would be much the same to an IR query pointed at a boot. Eventually of course when the joint is badly damaged and beating itself apart that may change. But those initial heat conditions would not be detected by an IR gun laying under the Van.

Temp of two normal and identical CVs would be expected to be the same simply because all else equal the temp is a proxy for applied torque. Apply more torque, generate more heat.

What is different about the heat generated by an extended CV is WHERE it is generated, but a reading of the joint would not catch that so easily outside a lab. That's the heat I'm worried about. Somewhere inside a joint sustaining damage is a super hot spot where the pressure between metal parts (and the localized spot of heat this creates) is overwhelming the lube. But a reading of the joint from outside using an IR gun would show either no difference, or a minor one.

Understand the physics of a CV as to heat. In a CV, the heat is generated in a tiny little arc in each cavity of the star where the ball rolls along. It rolls along under pressure that is determined by the torque of the engine. That's it. All the heat comes from that arc (yes, some minor other friction things but inconsequential). And we know heat flows from hot areas to cooler areas. So the heat is handled by the joint itself acting like a heat sink - drawing off the heat and radiating it out. The grease also absorbs and disperses the heat.

If the arc is too close to an edge of the part (such as an extended CV), then the part is really hot on that end and cooler on the other end. That may mean a river of heat is flowing into the grease off one end of the part that exceeds the grease's rating. Or the part itself is so hot on that end that the metal is softening (because there is not more metal next to the heat source to quickly draw heat off). That's just one example of heat causing things not to wear properly.

Of course, if you add more torque (such as an engine swap) then that arc may be way hotter than the part was designed to be. And it sheds metal that now becomes sandpaper to grind the already too hot arc of contact into a groove very quickly.

But none of this would neccessarily be visible to an IR gun.

What's my point? That opening two identical joints run for the same miles and visually looking at the differences will tell much more than periodic heat gun queries. Both joints will shed close to the same amount of heat for the heat gun to see, but deep inside of them the hot spots may be very different. The wear patterns are better indicators of what is going wrong.

I think CVs made for higher output engines (with better materials including the mentioned heat/cryo treatments) to match an engine swap are the solution and answer. I don't think polishing is going to make much of a difference. A joint quickly smooths in its wear path and it does it by rolling, not sliding - work hardening any high spots down (such as minor machining texture). Is a polished joint better? Yeah. But measurably better in a way that measurably increases component life? I don't think so.

DougM
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[Syncro Jael]

[j_dirge]

[IdahoDoug]

Jael,

Yep, you r correct in all respects. On function of grease - yes exact goal is no metal to metal contact. Same as all lubes essentially. When either gear pressure is too high for design PSI, or heat is too high (from psi or other heat source) for lube to handle then metal to metal and damage happens. The tiny little point of contact has an extraordinary amount going on. Incredibly, just the thinnest film is in there and that's all it takes.

As for adding grease actually you can add too much in some joint designs and add rotating friction with no added lube benefit. I think in this case it would just shorten boot life in extremis, but doubt you are there.

On moly, it is typically used in exactly this application - high load low speed bearings. From what I recall the moly is in the form of microscopic blobs that sacrifice themselves when trapped in the pressure point and smear. It fills microscopic pores and voids, helping the much smaller oil particles do its job. Great stuff. I don't have the grease I repacked my CVS handy but I would think VW specs it here, yes?
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[Jon_slider]

[Syncro Jael]

Here are some earlier CV temps that I have recorded in other posts.

[j_dirge]

I did not take pics of my 944 CVs, but they are most certainly a different compostion. They are a darker gun metal, where the Vanagon CVs are more silver in tone.

HOWEVER! My 944CVs came brand new out of the box.. stiiffer than ANY CV I have held in my hand yet.
It took me aback..

SO I worked grease into them and MANUALLY worked them loose enough to flex. I had to do that just to install them.
Then I drove a few miles at low load (flat roads, no cargo loads, no laying into the pedal)
I put the van back into the garage an slid the axles back and forth.. much smoother.
I unbolted the inner CVs and checked articulation and they were smoother but still on the stiff side.

I then did a 400 mile trip.
Checked again.
Axles slide even easier, and the inner CVs are buttery smooth, and articulate nicely.

BUT.. I started hearing a light and muffled whoomp whoomp two days ago..
Last time I heard that noise, a boot had torn.
I'll be damned if an outer boot tore at less than 1000 miles.
I'll be checking it out in a day or two.. and will report back.
_________________
-89 GL Westy, SVX.. finally.

-57 pan f/g buggy with a 67 pancake Type 3 "S"
"Jimi Hendrix owned one. Richard Nixon did not"
-Grand Tour, Season 1, episodes 4 and 5

[MarkWard]

What annoys me is I have a 2002 Acura RSXS with 220,000 miles on it. Original CV's and boots. In my days at the VW and Audi dealers, the majority of the CV work we did was replacing torn boots. Very rarely would you come across pitted joints as shown above. Now it seems almost common place. Granted I am making more power at a stock ride height, but in my case the one CV I had replaced of 4, was the one that failed prematurely. Good reading.
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☮️

[Waldi]

[Wildthings]

[dobryan]

thousand?
_________________
Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

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[j_dirge]