Broken yella terra rocker arm
12-22-2013, 11:52 AM
#1
Broken yella terra rocker arm On Friday we had my camaro on the dyno and had a rocker break right as we began the first wot pull. I've had these on my car since 2009 and had just swapped springs from the stock trick flow 215cc ones to brian tooley .650's. Im guessing my old springs were a little weaker than I had thought. Anyways I'm pretty sure my yellas were the old design because the 1.7 is stamped to the left of the center on top of the rocker. Anyways I'm kinda scared to get a another set of these, what other rockers do you guys recomend for trick flow heads?
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12-22-2013, 06:16 PM
#10
You may want to simply replace them with the Yella Terra Generation III rocker. They are stronger for the higher force springs. I would verify they can handle your open spring forces though. I think Brian is going to recommend not using stock rockers, unless you want to replace guides in 10K miles.
Two other recommendations:
1. Ensure the wipe pattern is perfect, which may require shim thickness other than provided by Yella Terra. Mine required different shims on my AFR heads.
2. If you haven't already, go with larger OD pushrods. I went with 3/8" double taper and noticed an immediate change in the upper RPM. In other words, they were bending.
Two other recommendations:
1. Ensure the wipe pattern is perfect, which may require shim thickness other than provided by Yella Terra. Mine required different shims on my AFR heads.
2. If you haven't already, go with larger OD pushrods. I went with 3/8" double taper and noticed an immediate change in the upper RPM. In other words, they were bending.
12-25-2013, 11:18 AM
#11
I have gone through 2 sets of YT rockers since 2010, I think i had the GEN I and II. my first set broke at the pedestal. the second set seized rotating and took part of my motor with it. So I am biased when I say I will never use YT again. less than 20k miles was put on the car in that period. YT did replace my 1st set free of cost, and I just said screw it with the 2nd set. went with another company.
12-25-2013, 04:53 PM
#12
As i stated earlier, i have the "Gen III" Yella Terra's and they are great. My open spring pressures are almost 500 in lbs. These are the springs i have:
http://www.texas-speed.com/p-473-pre...pring-kit.aspx
So the Yella Terra's are definitely able to handle harsh spring pressures. I have had my motor up to 6900rpm (+/- 50 rpm) as well on the dyno, with the redline currently set at 6800.
http://www.texas-speed.com/p-473-pre...pring-kit.aspx
So the Yella Terra's are definitely able to handle harsh spring pressures. I have had my motor up to 6900rpm (+/- 50 rpm) as well on the dyno, with the redline currently set at 6800.
12-27-2013, 08:01 AM
#13
I have gone through 2 sets of YT rockers since 2010, I think i had the GEN I and II. my first set broke at the pedestal. the second set seized rotating and took part of my motor with it. So I am biased when I say I will never use YT again. less than 20k miles was put on the car in that period. YT did replace my 1st set free of cost, and I just said screw it with the 2nd set. went with another company.
If money were no object, I would go with the Jesel Pro Steel, but they are over $2,000 for a set.
12-30-2013, 01:23 PM
#15
I too had a yella terra rocker break and take a piston and head with it. I also run TFS heads.
When I put it back together, I put stock rockers in it. The car has run better than it ever did with the YTs, but I am well aware of the premature wear with the bronze guides.
My plan, if you can call it that, is to run it as is until/unless I start to see an issue and then have the bronze guides replaced with powedered metal guides and stick with the stock rocker.
When I put it back together, I put stock rockers in it. The car has run better than it ever did with the YTs, but I am well aware of the premature wear with the bronze guides.
My plan, if you can call it that, is to run it as is until/unless I start to see an issue and then have the bronze guides replaced with powedered metal guides and stick with the stock rocker.
12-31-2013, 07:58 PM
#16
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I too had a yella terra rocker break and take a piston and head with it. I also run TFS heads.
When I put it back together, I put stock rockers in it. The car has run better than it ever did with the YTs, but I am well aware of the premature wear with the bronze guides.
My plan, if you can call it that, is to run it as is until/unless I start to see an issue and then have the bronze guides replaced with powedered metal guides and stick with the stock rocker.
When I put it back together, I put stock rockers in it. The car has run better than it ever did with the YTs, but I am well aware of the premature wear with the bronze guides.
My plan, if you can call it that, is to run it as is until/unless I start to see an issue and then have the bronze guides replaced with powedered metal guides and stick with the stock rocker.
Other of that, someone misunderstood valve-train dynamic and it's better to stick in the lower league.
Christian
12-31-2013, 08:43 PM
#18
The YT Utralite cannot technically be worse than stock rocker rationally in any manner...BUT...only if your entire valve-train is perfectly balanced and matched between each of the component after that upgrade!!!
Other of that, someone misunderstood valve-train dynamic and it's better to stick in the lower league.
Christian
Other of that, someone misunderstood valve-train dynamic and it's better to stick in the lower league.
Christian
12-31-2013, 08:53 PM
#19
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My engine is using YT Ultra Lites Gen III and revving on a daily bases to 7500 rpm, 664hp flywheels, bumping in the rev limiter when needed...something must be well done!
Sorry for your misadventure (costly one I guess).
Happy New Year
Christian
01-01-2014, 08:20 AM
#20
Many don't look at pushrods, and they can be a major contributor to broken parts, especially aluminum rockers. 5/16" pushrods are not stiff enough once you start getting into aftermarket springs. Hardened pushrods are not stiffer, and stiffness is best achieved by a large OD and not a smaller ID (thicker wall). In my case, I found a huge change in the upper RPM curve shape when I went to the 3/8" double taper pushrods (which also netted about 6 hp). I have spoken to several engine builders and my experience is typical.
Guess my point is that these failures have several contributors and may not simply be the rocker itself.
Guess my point is that these failures have several contributors and may not simply be the rocker itself.