Comp Trunnions after 12K Miles
#1
Staging Lane
Thread Starter
Comp Trunnions after 12K Miles
If anyone needs more convincing to check/get rid of your comp trunnions I thought I would share some pics. I decided to pull my ls3 rockers apart to check the trunnions after 12,000 street miles. These came already assembled on my PRC 260 cnc heads on my TSP 418 stroker. This is a street car that I have done a couple 5000 mile road trips with over the last couple years. Out of 16 rockers there were only 4 that I would have considered re-running and several have significant wear the entire width of the bearing needles and deep enough to catch a nail on. Glad I checked before they put any more metal through the motor.
Cam is a TSP 235/239, started with EHT .675 springs, now on PAC .660's. I have ordered Straub bushings to try next.
Cam is a TSP 235/239, started with EHT .675 springs, now on PAC .660's. I have ordered Straub bushings to try next.
#3
TECH Senior Member
Straub bushing upgrade....
#6
Now, take one of those trunions and have it Rockwell tested. It is probably somewhere in the 45-50 HRc range.
You will then understand why those grooves appear when you have 62 HRc bearing riding on a 50 HRc "race" in all regards.
Junk. Same with the Summit brand and probably BTR.
You will then understand why those grooves appear when you have 62 HRc bearing riding on a 50 HRc "race" in all regards.
Junk. Same with the Summit brand and probably BTR.
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#8
Staging Lane
Thread Starter
Now, take one of those trunions and have it Rockwell tested. It is probably somewhere in the 45-50 HRc range.
You will then understand why those grooves appear when you have 62 HRc bearing riding on a 50 HRc "race" in all regards.
Junk. Same with the Summit brand and probably BTR.
You will then understand why those grooves appear when you have 62 HRc bearing riding on a 50 HRc "race" in all regards.
Junk. Same with the Summit brand and probably BTR.
#12
If they would spend a few more bucks and use an inner race, this problem would be non-existent. They would probably have to charge an extra $20, but they would last 120k miles instead of 12k and you wouldn't be replacing them again.
Built in obsolescence is the name of the game!
Built in obsolescence is the name of the game!
#13
TECH Senior Member
One of the issues with the roller trunnions as I(and apparently others) see it, is that the few rollers on the bottom take all the load for their entire lives. Couple that with questionable metallurgy on the trunnions themselves and you have a recipe for eventual failure or even disaster. All this is known now, but for some at some expense.
Last edited by G Atsma; 04-10-2017 at 08:34 PM.
#14
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Look way better than mine did at that mileage. The comp kits are complete junk. Now up to ~7k on my smith bros ones and no issues so far, but haven't pulled one apart to inspect yet.
#16
Super Hulk Smash
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I one of the issues with the roller trunnions as I(and apparently others) see it, is that the few rollers on the bottom take all the load for their entire lives. Couple that with questionable metallurgy on the trunnions themselves and you have a recipe for eventual failure or even disaster. All this is known now, but for some at some expense.
#17
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If the straubs wear, it will be the softer bushing, not the trunion part. Will pull a few and check at 10k miles or so. At least if those wear, it is a cheap/quick/easy swap to put new bushings in.
#19
TECH Fanatic
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On the wear part. Anything in the valve train area is going to wear. When the bushing does wear, just like a bushing lifter, it is not going to put needle bearing in your engine that can fine their way to the oil pump. If this happens it is catastrophic damage from a needle in the pump.
#20
It all stems from a company using cheap *** chinese metal, welcome to the upcoming future. That is why I get such a laugh off of the dorman intake threads, they are the biggest pieces of, also made in china. China equals junk, period