New Trunnion Upgrade

[71RS/SS396]

the trunions look galled or worn under where the the bolt goes through, is that correct or is it just the picture maybe?

They're galled on the bearing surface, on the bottom side where all of the load is. It appears that the bearing itself gives up first and all of the debris from that is causing the trunion shaft to get galled.

[71RS/SS396]

Here's my first take on the comparision between the 2 bushing upgrade kits:

The CHE kit uses a spiral lock clip instead of a snap ring like the Straub kit.

The CHE trunion shaft is .709 vs .625 for Straub but this does make the bushing thinner than the Straub.

I still like the fact the Straub kit has oil grooves in the shaft

Both kits rotate very smoothly with vitually no drag, I honestly cannot tell the difference in resistance between the bushings and the needle bearing, but this is with no load so that could change.

When we pressed the bushings in flush with the outside of the rocker on the Straub kit there was .025" of axial movement of the shaft, so we machined up a fixture with a .01" step in it to press the bushing past the outside and closer to center which gave us .005" axial play and also makes it so the snap ring isn't trying to control the axial movement. I would like to see this bushing about .10" wider than it is but it's not the end of the world the way it is.

[1BADBET]

I can't tell how the rockers are fastened with the system your using but are they bolted down solid? Even if the bearings fail the bottom of the trunion where the bolt is wouldnt gall unless it's moving. I've never seen or heard of anyone using a girdle on a pedestal style rocker system and as far as I can tell this guy is the only one making them, so this is a first for me

[71RS/SS396]

I can't tell how the rockers are fastened with the system your using but are they bolted down solid? Even if the bearings fail the bottom of the trunion where the bolt is wouldnt gall unless it's moving. I've never seen or heard of anyone using a girdle on a pedestal style rocker system and as far as I can tell this guy is the only one making them, so this is a first for me

The bolt is not galling, that picture is of the trunion shaft, the bearing surfaces of the shaft are galling. We machine a collar that the rocker mounting bolt passes through and the bar clamps to those collars, Here's a pic of the stud girdle where you can see the underside. The stud girdle works just like one for a small or big block Chevy.

[1BADBET]

I port cylinder heads for a living, you can read the about me in my profile if you like I'm not some guy who learned the trade a jiffy lube. I do understand what is going on but maybe I'm not explaining myself very well.

A traditional small and big block Chevy has a screw in stud rocker that, for the lack of a better description, "floats" on the stud. The rocker is positioned near the top of the stud that is what causes the studs to flex, all the load is near the top, so the top of the studs are tied together to help keep them from flexing.

A stock lsx rocker IS a pedestal style, they're not individual like the jesel stuff most people associate with pedestal rockers but non the less they are. They do not float on the stud like the traditional Chevys do they are bolted to the head solid and the trunions sit on the rocker bar.

What I am trying to say is that the part of the trunion that sits on the tie bar is supposed to be bolted down and not move. From the picture it looks like that part of the trunion is also galling or showing wear just like the area where the bearings ride. This should never happen as they are "supposed" to be bolted down solid, even if the bearings fail or rocker breaks the trunion has a bolt going thru it and the trunion itself shouldn't move and it looks as if it is.

That's why i mentioned not being able to tell how the rockers are fastened to the head with your valvetrain. It would seem that they are not bolted down, or maybe that system with the girdle is converting the lsx rocker to a stud like the old stuff, which is a step back. That would explain the abnormal bearing wear and failure.

There is 15 different companies making stud girdles for a Chevy, none make one for an lsx engine. They make them for fords, that have been converted to Chevy style rockers. This is done because the Chevy style rockers are cheaper and easily adjusted. With a pedestal, lsx or ford or jesel, they need either an adjuster not on the pushrod side or shim the stand to set valvetrain geometry. The pedestal is either time consuming or expensive. My guess is the rockers are converted to stud for ease of adjustment. Adjusting the rocker bar is possible but time consuming and all the tip heights have to be right on, there are ways of making things a little easier but it takes a little time.

If you want to keep it cheap they make conversion studs for lsx heads and Chevy rockers but you need to use the Chevy rocker, the trunions are bigger in the center around the stud where it's going to want to bend up. (Imagine putting your finger on a piece of weld rod while it's on the bench and someone lifts both ends, it bends in the middle where your finger or in this case the bolt or stud, is.)

Again not trying to ruffle any feathers I'm just trying to help. I type like a talk and some people think I'm a lite rough till you get to know me. 4 years in the marines, 2 tours in Iraq, 0 sensitivity training lol :-)

[1BADBET]

And I believe jesel sells a rocker system for the ls7 head that requires no machine work. I'd give them a call if that's what your looking for.

[71RS/SS396]

I port cylinder heads for a living, you can read the about me in my profile if you like I'm not some guy who learned the trade a jiffy lube. I do understand what is going on but maybe I'm not explaining myself very well.

A traditional small and big block Chevy has a screw in stud rocker that, for the lack of a better description, "floats" on the stud. The rocker is positioned near the top of the stud that is what causes the studs to flex, all the load is near the top, so the top of the studs are tied together to help keep them from flexing.

A stock lsx rocker IS a pedestal style, they're not individual like the jesel stuff most people associate with pedestal rockers but non the less they are. They do not float on the stud like the traditional Chevys do they are bolted to the head solid and the trunions sit on the rocker bar.

What I am trying to say is that the part of the trunion that sits on the tie bar is supposed to be bolted down and not move. From the picture it looks like that part of the trunion is also galling or showing wear just like the area where the bearings ride. This should never happen as they are "supposed" to be bolted down solid, even if the bearings fail or rocker breaks the trunion has a bolt going thru it and the trunion itself shouldn't move and it looks as if it is.

That's why i mentioned not being able to tell how the rockers are fastened to the head with your valvetrain. It would seem that they are not bolted down, or maybe that system with the girdle is converting the lsx rocker to a stud like the old stuff, which is a step back. That would explain the abnormal bearing wear and failure.

There is 15 different companies making stud girdles for a Chevy, none make one for an lsx engine. They make them for fords, that have been converted to Chevy style rockers. This is done because the Chevy style rockers are cheaper and easily adjusted. With a pedestal, lsx or ford or jesel, they need either an adjuster not on the pushrod side or shim the stand to set valvetrain geometry. The pedestal is either time consuming or expensive. My guess is the rockers are converted to stud for ease of adjustment. Adjusting the rocker bar is possible but time consuming and all the tip heights have to be right on, there are ways of making things a little easier but it takes a little time.

If you want to keep it cheap they make conversion studs for lsx heads and Chevy rockers but you need to use the Chevy rocker, the trunions are bigger in the center around the stud where it's going to want to bend up. (Imagine putting your finger on a piece of weld rod while it's on the bench and someone lifts both ends, it bends in the middle where your finger or in this case the bolt or stud, is.)

Again not trying to ruffle any feathers I'm just trying to help. I type like a talk and some people think I'm a lite rough till you get to know me. 4 years in the marines, 2 tours in Iraq, 0 sensitivity training lol :-)

No offense taken, I just edited my earlier post since I realized what I typed was not accurate as far as the pedestal style rocker vs sbc/bbc. Everything is bolted down tight, nothing is moving. I'm not sure what you're seeing in the pic, most likely something looks odd due to the angle of the pics. I'm not really looking for cheap, I cannot use a Jesel set-up on the LS7 heads and I don't think they're necessary for the spring rates we're using nor do I want the added weight. I still believe the bearing selection in all of these needle bearing upgrades is where the problem lies. I just disassembled an engine that came back to be freshened up and 14 of the 16 shafts were damaged, the 2 that weren't the outer bearing race was damaged so they were on their way to damaging the shafts. I think the modified stock rockers will get the job done if we can solve the trunion bearing failure. I'm going to assume that you don't know who Kurt is based on your reply, he's a pretty smart guy that has been at the LS game as long or longer than anyone out there, he built a lot of the race engines for GM in the early LS days.

[1BADBET]

I'm not looking at what failed so much as I'm trying to figure out the why. This isn't an on the ragged edge race motor and i have used the trunion kits on several engines and know there is a ton out there having no issues either which makes me think there is another issue.

If you look at where the trunion would touch the rocker bar, that part looks like it's worn and this is supposed to be a non moving part. The second thing is the needles are wearing into the trunion in evenly. In the second picture it's digging in on the inner edge of only the one side and shows no wear on the outer edge of the trunion. It looks like there's something else going on. Either valve train harmonics or bolts stretching or a 100 other things, not just the bearing coming apart from abuse. If Thays the case the bronze bushings are gonna get ate up just the same as the needle bearings. I'd get new comp bolts for the trunion rockers and run it without the girdle see it that fixes it, it could also be the spring pressure, or valvetrain geometry and the rocker bar needs to be shimmed due to longer valves ect.

Just seems like there is more going on, I'd investigate further than just replacing the bushing.

[71RS/SS396]

I'm not looking at what failed so much as I'm trying to figure out the why. This isn't an on the ragged edge race motor and i have used the trunion kits on several engines and know there is a ton out there having no issues either which makes me think there is another issue.

If you look at where the trunion would touch the rocker bar, that part looks like it's worn and this is supposed to be a non moving part. The second thing is the needles are wearing into the trunion in evenly. In the second picture it's digging in on the inner edge of only the one side and shows no wear on the outer edge of the trunion. It looks like there's something else going on. Either valve train harmonics or bolts stretching or a 100 other things, not just the bearing coming apart from abuse. If Thays the case the bronze bushings are gonna get ate up just the same as the needle bearings. I'd get new comp bolts for the trunion rockers and run it without the girdle see it that fixes it, it could also be the spring pressure, or valvetrain geometry and the rocker bar needs to be shimmed due to longer valves ect.

Just seems like there is more going on, I'd investigate further than just replacing the bushing.

I've tried it with and without the girdle and had the same results, the geometry is fine, its been checked multiple times, we've done deflection tests to see if there's any thing crazy going on there too. We buy brand new heads from GM and send them to Advanced Induction and have them ported and completely checked out to make sure there's nothing goofy with the guides or seats. The shaft I posted just happened to be worn that way, some are worn evenly, as I said earlier the outer race of the bearing fails first. I think the damage to the shaft is a result of the trash from the outer race getting sent through bearing. This is a real problem with any engine that gets run hard with any regularity, you cannot see or feel this in the rocker until it completely disintegrates so if you haven't pressed them apart you don't know something is going on. Have you actually pressed apart the ones you say are fine? I've spoken to several people that specialize in cylinder head and valvetrain components and a lot of them are seeing the same thing infact some are about to stop selling the needle bearing upgrades. This is not a problem with one particular mfr. we've tried them all, the common denominator is they all utilize the same bearing. The bronze bushings have a lot more surface area so they will handle more load. I'm going to use the bushings in the 2 cars I personally own since I know they're not being over revved and I know what the maintenance level is on them. My car will be a good test since it has a far more aggressive cam in it and is harder on the valvetrain parts.

[1BADBET]

What kind of rpm are you turning? Who's cam is it?

[71RS/SS396]

What kind of rpm are you turning? Who's cam is it?

Comp, the engines typically peak at 6,800 but we recommend the rev limit be set at 7,000.

[Samckitt]

I am not a certified engineer, but have done engineering work in the past & was a product designer for years before I became a software product consultant For Siemens PLM Software. But I did stay at a Holiday Inn Express last night (LOL).

But Here is my thoughts/concerns.

I worked as a designer for about 5 years for a company that makes turbo chargers. One of the parts in the turbos I worked on was a thrust plate. It looks like this:


The three pads near the center are the areas where the mating part rides on. The recessed area around them is the area where oil travels. The 3 pads actually have a slight ramp on the leading edge that allows the oil to be “pulled” into the area where the pressure is applied to lubricate it. Obviously the turbo spins in one direction so the oil is constantly pulled onto the pads where it is needed.

These bushings for the rockers also have an oil groove to get the oil between the shaft & the bronze bushing. BUT, this bushing doesn’t make a full rotation around the shaft, so the oil never gets to the bottom side of the shaft where all the pressure is being applied. With only rotating (guessing) 15 degrees, the oil is not drawn down to where it is required, and with the force being applied at the bottom will push together tight & not allow the oil to penetrate.

If you look at standard small block chevy rocker arm pivot balls, they have oil grooves on them that allow the oil to get to the area where there is the most pressure.


So even though I like this design compared to the ones with all the little needle bearings, I’m not convinced these are going to work much better.

That’s just my opinion.

[1BADBET]

Factory redline on ls7 engines is 7000-7200rpm depending on who you talk to and lots of guys are moving that up. That's on the stock trunions. I've had guys turn 7500 all day no issues and know of several others doing the same. i think there has to be another issue causing your problem. I was expecting you to say your turning a lot more rpm than that. Old school Chevy stud rockers go 7k without a stud girdle and no problems.

[71RS/SS396]

Factory redline on ls7 engines is 7000-7200rpm depending on who you talk to and lots of guys are moving that up. That's on the stock trunions. I've had guys turn 7500 all day no issues and know of several others doing the same. i think there has to be another issue causing your problem. I was expecting you to say your turning a lot more rpm than that. Old school Chevy stud rockers go 7k without a stud girdle and no problems.

Yep, I know all of that. I'm not real sure why you think there's not a problem with these trunion upgrade bearings, if you google trunion upgrade bearing failure there's plenty of forum threads talking about it, this is not isolated to us. Kurt has been at the engine building game for more than 30 years, he understands the dynamics of an engine better than anyone I've ever met. He has a list of accomplishments a mile long and worked closely with GM developing the performance of the LS when he worked at Wheel to Wheel. He was the first one into the 6's in a LS and did it with a modified factory block with only 352 ci in a car borrowed from Mike Moran. I think he knows what he's doing.

[71RS/SS396]

I am not a certified engineer, but have done engineering work in the past & was a product designer for years before I became a software product consultant For Siemens PLM Software. But I did stay at a Holiday Inn Express last night (LOL).

But Here is my thoughts/concerns.

I worked as a designer for about 5 years for a company that makes turbo chargers. One of the parts in the turbos I worked on was a thrust plate. It looks like this:


The three pads near the center are the areas where the mating part rides on. The recessed area around them is the area where oil travels. The 3 pads actually have a slight ramp on the leading edge that allows the oil to be “pulled” into the area where the pressure is applied to lubricate it. Obviously the turbo spins in one direction so the oil is constantly pulled onto the pads where it is needed.

These bushings for the rockers also have an oil groove to get the oil between the shaft & the bronze bushing. BUT, this bushing doesn’t make a full rotation around the shaft, so the oil never gets to the bottom side of the shaft where all the pressure is being applied. With only rotating (guessing) 15 degrees, the oil is not drawn down to where it is required, and with the force being applied at the bottom will push together tight & not allow the oil to penetrate.

If you look at standard small block chevy rocker arm pivot balls, they have oil grooves on them that allow the oil to get to the area where there is the most pressure.


So even though I like this design compared to the ones with all the little needle bearings, I’m not convinced these are going to work much better.

That’s just my opinion.

I don't think this is a oiling problem, there's no evidence of heat/bluing which you would typically see with lack of lubrication. I have no idea what bronze material is being used since the standard answer you get is "it's a proprietary material" but there are several bronze materials that don't require direct lubrication. If you look at the pic of the Straub shaft it does have slots machined in it to direct oil into the bushing at the top.

[Samckitt]

I don't think this is a oiling problem, there's no evidence of heat/bluing which you would typically see with lack of lubrication. I have no idea what bronze material is being used since the standard answer you get is "it's a proprietary material" but there are several bronze materials that don't require direct lubrication. If you look at the pic of the Straub shaft it does have slots machined in it to direct oil into the bushing at the top.

"At the top" is the key words. It is rotating back & forth, not a complete revolution. With the tubro, there is a complete rotation so the oil is constantly drawn into the contact surface between the bushing & the thrust surface. With the pressure between the rocker & the bushing being on the bottom side, & no complete rotation, oil isn't going to get in between them in that area. That's my thought.

[71RS/SS396]

For those still interested, following, doubting, hating, what have you. I pulled several rockers off of my car and pressed the bushings out, they look just fine, a light polishing on the load side but still look new where there's no load. This is after a few thousand miles which is where the needle style would start to show some signs of bearing failure. My car I would consider to be on the extreme since the cam is over .675 lift with aggressive ramp angles, spring pressures are 175-450, the engine is rpm limited at 8,000.

[LonnieJ]

Thanks for the update Tim

[Motown 454]

Thanks.

[71RS/SS396]

FYI, CHE is going to offer their bushings in a DIY kit now for $250.