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There is some great info in this thread. Unfortunately the failure mode found by the OP is not new and has occurred on several cars over the years. I have done some reading up on the various trunion "upgrade" options out there and here is what I found:
Comp Cams - $129
There are thousands of people using these with no issues. With that said, there have been many reported cases of galling of the trunion shaft. Unfortunately this doesn’t become evident until the bearing is removed from the trunion for inspection. I did not find any cases where this galling led to a catastrophic failure of the component. In several cases the bearing would spin freely but once disassembled the shaft was damage similar to the ones pictured in the OP. There have also been reported failures of snap rings breaking, which may or may not be the result of installation error.
Brian Tooley Racing - $115
From Brian Tooley’s post on tech almost a year ago regarding the difference between their product and Comp Cams:
“We use the same trunnions and bearings as Comp does, we use USA made bolts and larger snap rings that should never break and provide slightly better pricing.”
Harland Sharp - $273
While similar in basic design there are some key differences that justify the price difference. First, Harland Sharp cross drills their trunions to provide access for splash oil to get to the bearings. Second, the Harland Sharp trunions include hardened washers between the c-clips and the rocker. Lastly, the materials used are more suitable for this application.
I found this info from two posts on tech that has some very good info on the differences between Harland Sharp and the rest:
“The difference between the Sharp kit & most of if not all the less expensive kits is that they use full heat treated 52100 steel for the shafts & the others use a case hardened steel like 8620. The case hardened shafts are only a surface heat treat meaning the outside of the shaft is hard, prob .02-.030 deep but the inside is still soft. The case hardened shaft is a poor choice for something that has a hard bearing with & the load from the valve train on it.
There are plenty of unhappy people on here that have had the Comp kits fail, the early Harland Sharp kits also failed but I believe they had surface heat treated shafts also.”
“You are relying on a thin layer of hardened steel supported by a soft inside & 8620 that is typically used is not a good choice, the 52100 that Harland Sharp uses is a full heat treated steel used in some bearing applications.
And for everyone's information I am a tool & die maker @ the former GM owned former New Departure/AC Delco Chassis/Delphi bearing plant which made/makes bearings on all your vehicles so I know a little about bearings.”
As was mentioned in the above statement, Harland Sharp had similar failures in their early design. They changed the material and design to correct the galling being found on these “upgrades” and as I understand have not seen reports of the same failure mode.
CHE - $420
CHE offers a unique solution as they do not rely on a bearing but rather utilize a bushing. This is regarded by many as to be the ultimate solution to the problem. I have not found or heard of any reported failures with the CHE product. Of course that comes at a price.
Last edited by CorvetteCoop; 01-05-2015 at 05:46 PM.
There is some great info in this thread. Unfortunately the failure mode found by the OP is not new and has occurred on several cars over the years. I have done some reading up on the various trunion "upgrade" options out there and here is what I found:
Comp Cams - $129
There are thousands of people using these with no issues. With that said, there have been many reported cases of galling of the trunion shaft. Unfortunately this doesn’t become evident until the bearing is removed from the trunion for inspection. I did not find any cases where this galling led to a catastrophic failure of the component. In several cases the bearing would spin freely but once disassembled the shaft was damage similar to the ones pictured in the OP. There have also been reported failures of snap rings breaking, which may or may not be the result of installation error.
Brian Tooley Racing - $115
From Brian Tooley’s post on tech almost a year ago regarding the difference between their product and Comp Cams:
“We use the same trunnions and bearings as Comp does, we use USA made bolts and larger snap rings that should never break and provide slightly better pricing.”
Harland Sharp - $273
While similar in basic design there are some key differences that justify the price difference. First, Harland Sharp cross drills their trunions to provide access for splash oil to get to the bearings. Second, the Harland Sharp trunions include hardened washers between the c-clips and the rocker. Lastly, the materials used are more suitable for this application.
I found this info from two posts on tech that has some very good info on the differences between Harland Sharp and the rest:
“The difference between the Sharp kit & most of if not all the less expensive kits is that they use full heat treated 52100 steel for the shafts & the others use a case hardened steel like 8620. The case hardened shafts are only a surface heat treat meaning the outside of the shaft is hard, prob .02-.030 deep but the inside is still soft. The case hardened shaft is a poor choice for something that has a hard bearing with & the load from the valve train on it.
There are plenty of unhappy people on here that have had the Comp kits fail, the early Harland Sharp kits also failed but I believe they had surface heat treated shafts also.”
“You are relying on a thin layer of hardened steel supported by a soft inside & 8620 that is typically used is not a good choice, the 52100 that Harland Sharp uses is a full heat treated steel used in some bearing applications.
And for everyone's information I am a tool & die maker @ the former GM owned former New Departure/AC Delco Chassis/Delphi bearing plant which made/makes bearings on all your vehicles so I know a little about bearings.”
As was mentioned in the above statement, Harland Sharp had similar failures in their early design. They changed the material and design to correct the galling being found on these “upgrades” and as I understand have not seen reports of the same failure mode.
CHE - $420
CHE offers a unique solution as they do not rely on a bearing but rather utilize a bushing. This is regarded by many as to be the ultimate solution to the problem. I have not found or heard of any reported failures with the CHE product. Of course that comes at a price.
Very nice presentations.
One major component removed, to have better durability on the CHE is that, they don't ship their bushing as a kit. Bushing is only done in house.
Few other notables:
"C" clip retention is effective as long as it is not over stretched during R&R.
Skewed bearing installed will result is early failures and galled shaft, which serves as the inner race.
Racing cars in order to stay competitive, engines need rebuilds. Loads of OEM parts are used but basically, consumables.
On the other hand, DD can enjoy a relative trouble free life with selected components, installed properly to enhance its longevity.
I can finally write an update on my trunion modifications. I have put 6,000 miles on them with the oiling slits and they look great! I am very happy now and finally feel like I can relax.
Thanks everyone for some very good posts backed up by great information. I realized I could have just replaced them but I really wanted to try and figure this out. Maybe it will work for others.
Thanks VictorF for that post. I didnt know harland sharp already had it figured out. I will inspect again in another 6k (or before if the magnet is fuzzy)
Last edited by DerekeLakin; 02-18-2015 at 12:22 AM.
I'm going to dig this back up to ask what everyone thinks about the coloradoSPEED LS Rocker Arm Trunnion & Bushing Upgrade Kit?
The new bushing kit uses proven old technology in the LS Rockers. The design of the trunnion allows for constant oil to the bushings. Even when long term storage of the engine happens, the oil channel holds oil in place and during start up after sitting oil instantly supplied to the bushing.
Kits can be used with OEM bolt and/or aftermarket bolt or stud.
The new bushing kit uses proven old technology in the LS Rockers. The design of the trunnion allows for constant oil to the bushings. Even when long term storage of the engine happens, the oil channel holds oil in place and during start up after sitting oil instantly supplied to the bushing.
Kits can be used with OEM bolt and/or aftermarket bolt or stud.
Can I ask why you guys are modding your rockers? As reported by many, including Jason from Katech's very compelling evidence, the stock rockers are great. Why spend money and get something less reliable?
This is an honest question not trying to be a smart aleck, I've seen no need to "upgrade" but if there was a compelling reason, I would. My car sits a fair amount now so if there's something to be done better for cars that aren't daily driven, I'd be interested in that.
So far, all I've seen is failures from this "upgrade"...
Can I ask why you guys are modding your rockers? As reported by many, including Jason from Katech's very compelling evidence, the stock rockers are great. Why spend money and get something less reliable?
This is an honest question not trying to be a smart aleck, I've seen no need to "upgrade" but if there was a compelling reason, I would. My car sits a fair amount now so if there's something to be done better for cars that aren't daily driven, I'd be interested in that.
So far, all I've seen is failures from this "upgrade"...
The bushing design has an oil channel that stores oil. Great for cars that sit for long periods. With change of cam profiles and more aggressive spring loads the needles in the OEM design can fail also. Unlike a needle bearing, if the bushing fails it just wears down and does not spit out needles into the engine that can cause catastrophic failure.
The bushing kits offer peace of mind to the guy/gal that has modified their engine.
The bushing design has an oil channel that stores oil. Great for cars that sit for long periods. With change of cam profiles and more aggressive spring loads the needles in the OEM design can fail also. Unlike a needle bearing, if the bushing fails it just wears down and does not spit out needles into the engine that can cause catastrophic failure.
The bushing kits offer peace of mind to the guy/gal that has modified their engine.
I see. Actually I don't recall seeing any failures from stock rockers in modded engines, including mine, except for the early Z06 rockers.... But I haven't been on the forum as much lately so perhaps things have changed.
COSPEED mentioned that the first batch came as bulk so they didn't have boxes for them. Straub underestimated how many would sell so he didn't have boxes for distributors.
01-05-2015, 01:16 PM
