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I brought up your findings in this thread and others after members asked about the longevity of traditional needle bearing style trunion kits versus what could be expected with the bushing style trunion kits.
I'm glad you chimed in and were able to validate this.
Your experience and knowledge are a huge benefit to the ls community Kurt. Are you seeing any additional or added wear on the exhaust trunions Kurt? Especially in higher HP/higher cylinder pressure type applications where there is more load placed on the exhaust side of the valve train?
You can easily see where the individual needles that were receiving all of the load wore into the trunion. By spreading this load out with a bushing, using a REM polished tool steel trunion and the additional oiling the Straub kit provides from the dedicated oiling channels, this wear seen in Kurt's pictures will be a thing of the past.
Anyone with a needle bearing kit should highly consider swapping to this bushing style kit.
Should we of expected anything else Chris?
I got schooled in needles my Mr. Morel at PRI show. With anything there are different quality levels. Needle bearings are the same. Most needle assemblies are ground to a tolerance of .0002" and shipped out. The next level of quality sorts these in batches that are within .00005". That is 50 millionth. As explained to me by Mr. Morel, the needle that is the largest OD bears the load. With the bushing, the load is distributed.
All of the driving experience corvettes will be retro fitted with the bushing kits. We should log over 200K miles by the end of the year. And let me say this is not new technology, Ford and Chrysler ran bushing shaft rockers decades ago on production vehicles. They just didn't get to enjoy the tolerances and finishing that we can achieve today.
Is it better to get these with the bolts or not? Are the replacement bolts shorter to aid in not protruding into the intake tract of ported heads? Thinking about just throwing a set of these in my LS7.
Found out my 36k mile 09 Z06 is on motor number 2, as the first one popped at 22k.
I do not understand. If you are racing this car often, I would assume you have other reasonably high dollar parts in the car/engine. Why are you not using a set of Jesel roller rockers instead of some cheap factory rockers with an upgrade roller kit? Harland Sharp and Yella make some good roller rockers that will hold high spring pressure etc. where the bearing do not wear out. Why would you not use something designed for racing? If I had a new crank, pistons, rods, heads, cam, and intake, I sure wouldn't hesitate to buy a set of high quality rockers.
When I look at the wear, it looks like a lot more than 3-4 rollers are contacting the surface as what is being said. It looks like it has about 30-40% contact area. I hope the new bushing kits work for you, because I do not think the cheap roller upgrade kits were designed for the applications you are using them for. As for the probably thousands of other people using them, they are probably working fine.
Tip weight is the big issue with fast ramp cams and high rpms, the factory rockers are strong and light, that's why they're preferred. Additionally a radius type rocker tip doesn't wear out parts more quickly simply because there's more surface contact.
Originally Posted by dr_whigham
Is it better to get these with the bolts or not? Are the replacement bolts shorter to aid in not protruding into the intake tract of ported heads? Thinking about just throwing a set of these in my LS7.
Found out my 36k mile 09 Z06 is on motor number 2, as the first one popped at 22k.
Hmm. I wonder why...
I ship replacement bolts with our setup to eliminate what protrudes into the port like you said. As I've posted before, you need to be careful with these kits and the LS7 rockers, we found that the LS7 bodies are .001" tighter than the LS1/2/3 rockers and need to be honed so that the trunnion doesn't lock up from a lack of clearance.
Tip weight is the big issue with fast ramp cams and high rpms, the factory rockers are strong and light, that's why they're preferred. Additionally a radius type rocker tip doesn't wear out parts more quickly simply because there's more surface contact.
I ship replacement bolts with our setup to eliminate what protrudes into the port like you said. As I've posted before, you need to be careful with these kits and the LS7 rockers, we found that the LS7 bodies are .001" tighter than the LS1/2/3 rockers and need to be honed so that the trunnion doesn't lock up from a lack of clearance.
Agreed 100% on the added moment of inertia that a bulkier roller rocker or shaft rocker adds. It's much easier to control a lighter weight lower mass factory rocker. Especially on an engine that sees extended duration of high RPM's. I believe PAC did a spintron test with stock rockers versus roller rockers. They used the same camshaft, lifters, push rods and valve springs and only changed the rocker arm. IIRC they took the stock rocker to 8000rpm before they saw pronounced valve float. Whereas the roller rocker ran into the same pronounced valve float just above 6000rpm. I can't remember ever seeing a broken stock rocker either as they are very strong. Of course we've all seen busted OEM trunions, but not the actual rocker body itself. I think you'd be hard pressed to find a case where an actual stock LS rocker body had been broken.
Are the bolts you're using the same as the ones that Chris is now supplying as an upgrade? Dave (Dr. Whigham) asked me in an email if the upgraded rocker bolts were shorter and I honestly couldn't tell him one way or the other.
I ship replacement bolts with our setup to eliminate what protrudes into the port like you said. As I've posted before, you need to be careful with these kits and the LS7 rockers, we found that the LS7 bodies are .001" tighter than the LS1/2/3 rockers and need to be honed so that the trunnion doesn't lock up from a lack of clearance.
Agreed 100% on the added moment of inertia that a bulkier roller rocker or shaft rocker adds. It's much easier to control a lighter weight lower mass factory rocker. Especially on an engine that sees extended duration of high RPM's. I believe PAC did a spintron test with stock rockers versus roller rockers. They used the same camshaft, lifters, push rods and valve springs and only changed the rocker arm. IIRC they took the stock rocker to 8000rpm before they saw pronounced valve float. Whereas the roller rocker ran into the same pronounced valve float just above 6000rpm. I can't remember ever seeing a broken stock rocker either as they are very strong. Of course we've all seen busted OEM trunions, but not the actual rocker body itself. I think you'd be hard pressed to find a case where an actual stock LS rocker body had been broken.
Are the bolts you're using the same as the ones that Chris is now supplying as an upgrade? Dave (Dr. Whigham) asked me in an email if the upgraded rocker bolts were shorter and I honestly couldn't tell him one way or the other.
I understand the concept, but he is taking a rocker/trunion set-up that was made to go to maybe 7k once in a blue moon in a street car, changing the bearing, and expecting it to live in a race car. It wasn't designed to do that. Then complaining that it won't live under racing conditions and they wear out. If you want durability, you probably need to buy a good set of rockers with good bearings that don't wear out like the Jesel shaft units that run $1300 instead of a $99 upgrade kit.
Again..for street use, there are probably thousands of these retro fit kits out there that have gone thousands upon thousands of miles without a problem. Telling everybody they need to change them out sounds a bit more like a scare tactic to sell more product. If bearings are so bad, then why are you not telling everybody to swap out their roller lifters and go to non-roller solid/hydraulic lifters? Seems like they would be an accident waiting to happen also.
Originally Posted by Cstraub
All of the driving experience corvettes will be retro fitted with the bushing kits. We should log over 200K miles by the end of the year. And let me say this is not new technology, Ford and Chrysler ran bushing shaft rockers decades ago on production vehicles. They just didn't get to enjoy the tolerances and finishing that we can achieve today.
This is not a good comparison. Those production engines had a max RPM of maybe 6k and only hit that when their 16 year old son drove the car on Friday nights. The minute you went to a roller cam with high lift and long duration, high spring pressures, and other variables, those bushing style rockers hit the trash and roller rockers were installed. This was done to cut down on resistance in the valvetrain and also to reduce the heat caused during high RPM running with the load only being put on a small portion of the bushing. How many high performance/racing aftermarket rocker arms used bushings in old Fords or Mopars?
Last edited by joyridin'; Feb 25, 2016 at 06:04 PM.
If bearings are so bad, then why are you not telling everybody to swap out their roller lifters and go to non-roller solid/hydraulic lifters? Seems like they would be an accident waiting to happen also.
You do know who Kurt Urban is right? He has probably put more engines together and had more experience with LS engines than anyone in this industry. If he felt that was the best way to go, then that was the best way to go.
The needle bearings that encapsulate a LS stock rocker arm do not rotate 360* like needle bearings that encapsulate a lifter axle. Two totally different applications. The same needles are loaded over and over again with a stock LS rocker arm versus a roller lifter that "rolls" and allows the bearings to rotate 360*.
There are many manufacturers that now sell roller lifters that utilize a bushing to encapsulate the axle on a roller lifter. They are using bushings because they spread the load out over a larger surface area and thus can handle much more spring pressure and RPM. They are superior to a needle bearing in this aspect which is why using a bushing to encapsulate a LS rocker arm trunion is a better idea. Since that bearing or bushing is loaded over and over again, it is better to use a bushing that spreads that load out over a larger amount of area and doesn't concentrate load in a smaller amount of surface area as seen in Kurt's pictures.
I would be willing to bet that if you were to examine the trunions on a street/strip engine with moderate valve lift and duration and one that has over 10K miles you'd see very similar wear. The physics involving that wear doesn't change no matter if it's a street/strip application or a road course application. Yes the road course engine may have more high RPM cycles, but the load is still similar and still concentrated in the same area.
I'll let Kurt give his experiences with street/strip type engines and not try to put the cart too far in front of the horse, but I am willing to bet he has seen the same wear in less demanding applications.
Here's some more pics. After following these threads on the new bushing style trunions I decided to pop a couple rockers off and check them. I have noticed over time the valve train getting a little louder. Guess what? They look just like the pics above. TV2 cam, probably 2-3 years on the comp trunion upgrade(20,000 miles give or take). Some drag racing and nitrous. Straub kit is sitting in the garage to be installed. The bolts from the comp kit I have will work just fine.
Kurt while your checking in on this thread I'm considering swapping pushrods while in doing the rockers. I just have 7.4 5/16 in there now with 0.95 oiling holes. Was considering Manton 11/32 stage 3 with 0.60 oiling holes.
Here's some more pics. After following these threads on the new bushing style trunions I decided to pop a couple rockers off and check them. I have noticed over time the valve train getting a little louder. Guess what? They look just like the pics above. TV2 cam, probably 2-3 years on the comp trunion upgrade(20,000 miles give or take). Some drag racing and nitrous. Straub kit is sitting in the garage to be installed. The bolts from the comp kit I have will work just fine.
There you have it, the same wear that Kurt showed in his engines are also seen in this street/strip application. I'd bet that there will be many more pictures like this being posted soon.
Straub should be highly commended for offering a superior product at a great price point that will hopefully solve this issue for good.
I'm excited to hear the continued testing results from Straub's driving experience customer and Kurt's findings in his road racing engines.
Kurt while your checking in on this thread I'm considering swapping pushrods while in doing the rockers. I just have 7.4 5/16 in there now with 0.95 oiling holes. Was considering Manton 11/32 stage 3 with 0.60 oiling holes.
I've never ran a restricted oiling pushrod on a hydraulic ls engine, but I'd think that they aren't absolutely needed unless you were running a very limited travel lifter. The increase in OD diameter on the push rod is never a bad idea as I personally like to fit the absolute largest push rod possible.
I'd like to hear Kurt's thoughts on the restricted push rods on a hydraulic roller application.
Well hell... A thousandth is enough to cause an issue?
I feel like just pulling a Ron Burgundy right now, lighting my cigarette, and drinking my scotch. I mean production tolerances on LS1/2/3/6 bodies themselves would surely be a thousandth.
Back to the drawing board for me then. I'm going to venture a guess "machinistone" works for / at Straub?
The balance of weight over performance is why I use the stock rockers, they are the best product for this application. I use Jesel rockers on solid roller engines when spring load can be increased without causing lifter problems. It looks like the first failure point in my testing has been the outer race, then the shaft gets damage. I think the stock bearings might work better, but they are limited in travel for ease of install on the assembly line and fragile to valve toss damage.
Kurt
Originally Posted by joyridin'
I do not understand. If you are racing this car often, I would assume you have other reasonably high dollar parts in the car/engine. Why are you not using a set of Jesel roller rockers instead of some cheap factory rockers with an upgrade roller kit? Harland Sharp and Yella make some good roller rockers that will hold high spring pressure etc. where the bearing do not wear out. Why would you not use something designed for racing? If I had a new crank, pistons, rods, heads, cam, and intake, I sure wouldn't hesitate to buy a set of high quality rockers.
When I look at the wear, it looks like a lot more than 3-4 rollers are contacting the surface as what is being said. It looks like it has about 30-40% contact area. I hope the new bushing kits work for you, because I do not think the cheap roller upgrade kits were designed for the applications you are using them for. As for the probably thousands of other people using them, they are probably working fine.
The cars I work on drive to the race, then run on the racetrack. They are not racecars, they just run like them.
Kurt
Originally Posted by joyridin'
I understand the concept, but he is taking a rocker/trunion set-up that was made to go to maybe 7k once in a blue moon in a street car, changing the bearing, and expecting it to live in a race car. It wasn't designed to do that. Then complaining that it won't live under racing conditions and they wear out. If you want durability, you probably need to buy a good set of rockers with good bearings that don't wear out like the Jesel shaft units that run $1300 instead of a $99 upgrade kit.
Again..for street use, there are probably thousands of these retro fit kits out there that have gone thousands upon thousands of miles without a problem. Telling everybody they need to change them out sounds a bit more like a scare tactic to sell more product. If bearings are so bad, then why are you not telling everybody to swap out their roller lifters and go to non-roller solid/hydraulic lifters? Seems like they would be an accident waiting to happen also.
This is not a good comparison. Those production engines had a max RPM of maybe 6k and only hit that when their 16 year old son drove the car on Friday nights. The minute you went to a roller cam with high lift and long duration, high spring pressures, and other variables, those bushing style rockers hit the trash and roller rockers were installed. This was done to cut down on resistance in the valvetrain and also to reduce the heat caused during high RPM running with the load only being put on a small portion of the bushing. How many high performance/racing aftermarket rocker arms used bushings in old Fords or Mopars?
Here's some more pics. After following these threads on the new bushing style trunions I decided to pop a couple rockers off and check them. I have noticed over time the valve train getting a little louder. Guess what? They look just like the pics above. TV2 cam, probably 2-3 years on the comp trunion upgrade(20,000 miles give or take). Some drag racing and nitrous. Straub kit is sitting in the garage to be installed. The bolts from the comp kit I have will work just fine.
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. The minute you went to a roller cam with high lift and long duration, high spring pressures, and other variables, those bushing style rockers hit the trash and roller rockers were installed. This was done to cut down on resistance in the valvetrain and also to reduce the heat caused during high RPM running with the load only being put on a small portion of the bushing. How many high performance/racing aftermarket rocker arms used bushings in old Fords or Mopars? 
