Comp Trunnions after 12K Miles - LS1TECH - Camaro and Firebird Forum Discussion

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Comp Trunnions after 12K Miles

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Old 04-08-2017, 09:17 AM
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Default 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.
Attached Thumbnails Comp Trunnions after 12K Miles-20170408_080931.jpg   Comp Trunnions after 12K Miles-20170408_080856.jpg   Comp Trunnions after 12K Miles-20170408_080844.jpg  
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Old 04-08-2017, 10:30 AM
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Wow you would think Comp would pull this product .
I just got a set for a 416 stoker me and my son are building . Looks like they will be sold at a loss of money .
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Old 04-08-2017, 10:41 AM
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Straub bushing upgrade....
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Old 04-08-2017, 11:51 AM
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Thanks guys.
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Old 04-08-2017, 12:05 PM
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Just ordered the Straub upgrade. Had it in the plans for a while, but finally pulled the trigger this morning after seeing this.
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Old 04-08-2017, 03:59 PM
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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.
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Old 04-08-2017, 04:27 PM
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Straub also. Glad I asked around.
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Old 04-08-2017, 04:51 PM
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Originally Posted by joyridin' View Post
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.
Agreed, especially in an application with very limited rotation so they are constantly running in a very small area. If it was a full rotation application they may be fine. You can see areas where the surface had broken down completely and starting to flake off.
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Old 04-08-2017, 06:31 PM
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Well ****, at least my comp trunnions are just in my rocker arms but not installed in my car.
Looks like a re-due switching to Straub
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Old 04-08-2017, 08:42 PM
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One more with comp kit for sale !!
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Old 04-09-2017, 12:47 AM
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The Straub/Smith Bros trunnions have revolutionized LS OEM rocker arms... COMP trunnions suck.
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Old 04-09-2017, 09:30 AM
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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!
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Old 04-09-2017, 10:13 AM
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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.
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Old 04-10-2017, 05:00 PM
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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.
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Old 04-10-2017, 05:12 PM
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Originally Posted by 64post View Post
Straub also. Glad I asked around.
Care to elaborate? Are you saying the Straub kit will wear the same way?
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Old 04-10-2017, 05:14 PM
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Originally Posted by G Atsma View Post
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.
This is the basic idea with eliminating the needle bearings in solid roller lifter combos and moving to a full bushing. Only a few needle bearings hold the load and they are bound to crap out eventually...
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Old 04-10-2017, 05:27 PM
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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.
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Old 04-10-2017, 08:38 PM
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Ordered Straub kit with bolts Saturday
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Old 04-11-2017, 10:35 AM
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Originally Posted by JakeFusion View Post
Care to elaborate? Are you saying the Straub kit will wear the same way?
I think he meant he ordered "Straub also".


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.
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Old 04-11-2017, 01:07 PM
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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
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