Cv prep already?

Loganhawkins418

Loganhawkins418

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what’s up guys! We have an Idaho Dunes trip coming up next month so I figured I’d get started on the prep (after pulling the back up ls2 out and putting the fresh 418” ls3 back in with new turbos and some other goodies)

But anyways, cv stars have some minor and some pretty bad pitting. Two of them have two seasons on them and two have one season, one star is still in good shape. Just wanted to get some opinions on the cause of this pitting…

Axles are strapped at 24 degrees

Cv’s were prepped pre season with certified premalube black Xtreme grease (the stuff that Alper recommends)

Cv’s are empi 934’s from Kartek, I believe they’re the stage two chromoly ones.

First season on them was running a twin turbo 418” ls3 that made just shy of 800whp on low boost. Second season was one trip on the big motor, lost oil pressure so I pulled it to rebuild and swapped in a stock stroke ls2 (rod and piston motor, ported heads big cam etc, with the twins installed, 600-800hp playing with the boost levels all season from 5-15psi)

New motor is making about 780 on 7psi, 1150 on 15 but I likely won’t turn it up that high, car weighs 2800lbs

So, are they just cheap china cv’s, not enough grease or not quality enough grease, to much angle, to much power for the cheap cv’s?

Of course I know they’re bottom of the barrel cv’s but they’re holding up pretty well so far and I know many people swear by the empi’s for 934’s

Thoughts?IMG_1239.jpegIMG_1238.jpegIMG_1237.jpegIMG_1236.jpeg
 
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J Alper said:
pittings is where the metal gets so hot it can stick to the CV,
If you broke the CV, I would say you need a stronger CV, with pitting, it needs better grease, or grease them more often, or angle is over limit,
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I always thought the pitting was from shock load but that makes sense! I’ll likely just replace the stars for now and maybe upgrade to some higher quality cv’s later.
 
The EMPI CVs are made from a material similar to 1045, which is decent for light-duty or casual use, but nowhere near the durability of the higher-end stuff. The better CV joints are made from 4000 series alloy steels—big difference in strength and longevity.


One thing that goes a lot further than people think is deburring the edges of the CV stars. It helps prevent cracking and pitting, especially when you’re running high angles or big power. A little attention there makes a big difference.


Also—if your car is strapped at 24 degrees—is that metal-on-metal through the bypass, or are you on a limit strap at that angle? I always recommend strapping metal-on-metal at 23–24°, and then limit strapping it around 22–23°. That way you’re not blowing through your limit straps or shocking the CVs at full droop.


CV grease plays a huge role—probably the biggest one. I’m not super familiar with the grease @Alper uses, but I know he and others run it with success. Personally, I’m a big believer that keeping clean grease in the CV joint is more important than what grease you use, but obviously the two go hand in hand. Just make sure it’s staying in the joint all season—CV pitting & failures often start from lack of lubrication.


There are a lot of tricks we use to make these CVs live—we’ve learned a lot over time. They’re expensive, yeah, but there’s real value in the good ones. We’ve run a ton of test miles with Kevin & Connor from Kevin McMullen Racing, and honestly, no one drives harder than Connor.

With all that said, the EMPI joints have there place & we sell quite a few. Nobody knows a shoe string sand rail budget better than me, with that said going with Kartek GKN, Pro am, fortin, gear one, or any other higher end CV joint is probably a good investment if you plan on keeping your car and driving hard.
 
Based on the knurling on the corners, it looks like you’re exceeding limit on those.

How are you measuring angle? Like @parker@gearone says, metal to metal, or on the strap is a bit of a difference, and you want to confirm they rotate easily by hand at full droop plus a little.
 
Thanks for all the input! I have the limit straps set with the axles at 23-24*. I just ordered some empi stars from kartek to replace these ones to get me through this Idaho trip, I’ll go to the gear one cv’s on the next round! I’ll also tighten up my angles to 22*. I always ran 22 when I had 930’s but last cv service with the 934’s they were at 23 and 23.5 if I remember right (I know they weren’t over 24) so I figured I’d just leave them there since I see people running even more angle than that. Angles are checked with a digital angle gauge that’s zero’d out on the chassis when checking them.
 
I've had good luck with Fortin 300m stars, in my 930 cvs. They're not bulletproof but they do last a very long time if the edges are knocked off. They're like $100 from Kartek. I cringe at the thought of even having to take a greasy cv apart. :ROFLMAO:

I've often wondered if you could take a worn out star, weld up the friction surface, make a jig to remachine it and reuse them. It's common to weld up industrial parts for remachining, but maybe a cv star isn't a good candidate for that? Might be easier to just buy new ones I suppose. Just thinking out loud. :unsure:
 
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KLC said:
I've had good luck with Fortin 300m stars, in my 930 cvs. They're not bulletproof but they do last a very long time if the edges are knocked off. They're like $100 from Kartek. I cringe at the thought of even having to take a greasy cv apart. :ROFLMAO:

I've often wondered if you could take a worn out star, weld up the friction surface, make a jig to remachine it and reuse them. It's common to weld up industrial parts for remachining, but maybe a cv star isn't a good candidate for that? Might be easier to just buy new ones I suppose. Just thinking out loud. :unsure:
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I ran the fortin stars when I had 930’s and also had great luck with them!
 
CV grease and keeping grease in is key.
I add grease every other trip.
I run 50/50 Belray/Swepco.
23 degrees.
Going on 4 seasons on mine.
1500 miles per season.
Blown LS1 for the past 4 seasons.

Here is a prime example.
Did CV prep on a buddy's Funco in November.
Pulled them down, found not much grease and very thin. Had been in there 1 season.
Stars were pitted, pretty bad on tranny side (typical).
I flipped the stars, added 200 pumps of grease with my gun, per CV.
I just torn them apart again last week and they still had a ton of grease in them and the new side of the star looked the same as when I put it in.
This was after 5 trips with a bunch of miles.
 
I had Empi in my new car. I repacked them once this year. They held up very well for the miles I put on them. I broke down and bought some gear-one CV's and replace them all a week ago. Keeping the empi ones for spares. I had no pitting, but some minor wear and burrs. I run the Belray/Swepco
 
Loganhawkins418 said:
Thanks for all the input! I have the limit straps set with the axles at 23-24*. I just ordered some empi stars from kartek to replace these ones to get me through this Idaho trip, I’ll go to the gear one cv’s on the next round! I’ll also tighten up my angles to 22*. I always ran 22 when I had 930’s but last cv service with the 934’s they were at 23 and 23.5 if I remember right (I know they weren’t over 24) so I figured I’d just leave them there since I see people running even more angle than that. Angles are checked with a digital angle gauge that’s zero’d out on the chassis when checking them.
Click to expand...
How are you measuring cv angle, measuring on the axle only give you Axle angle on CV's, you need to take a protractor on each cv and put one face on the cv body and one face on the axle, and get a angle of each cv at the tightest spot.
 
J Alper said:
How are you measuring cv angle, measuring on the axle only give you Axle angle on CV's, you need to take a protractor on each cv and put one face on the cv body and one face on the axle, and get a angle of each cv at the tightest spot.
Click to expand...
This^^^

It could add a few degrees you hadn't realized were there. It's not just the axle angle, but the set back of the cvs because of arm length. Letting the arm droop usually brings the cvs back in line with one another but it's good practice to measure the tightest angle anyways. Of course no one ever measures it like Alper mentioned.
 
All I know is I hate doing CV's, so do them right the first time is my motto. In 25 years of Sand cars, only have had one CV wear out, and that was due to lack of grease (my fault). I check and add grease about every 7-10 days of duning.
 
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