neutron82

a lot of us are familiar with the bad design of the stock ls trunnions and the benefits of replacing them... years ago I had replaced mine with a set of comp trunnions and thought I would never have to worry about them again, I had even recommended them to many people... granted at that time they were the only ones offered and now you can get them from brian tooley and straub technologies and possibly other companies I am unaware of... the ones from btr are nearly identical in design to comp, they both use a sealed needle bearing to support the trunnion... the kit from straub is different in that it uses a bushing rather than needle bearings to support the trunnion and also has a flat machined into the tops of each trunnion that provide a passage for oil... this is where the design flaw is in the comp and btr kits, there isn't a clear passage for oil to lubricate the needle bearings and over time the trunnion begins to wear prematurely... I want to thank LoneStarFRC for bringing this to my attention in a thread from a week or so ago... after looking through the link he posted about comp's trunnions wearing prematurely I decided that I didn't even want to take the risk with mine, I was just going to replace them no question... a good friend of mine named Bret (blownbluez06 on the forum) happened to have the straub kits in stock so I visited him earlier today and picked up a kit... I also figured since I was already there I might as well get some bigger pushrods due to the increased cylinder pressures on my car... I went with manton 11/32" diameter .120" wall thickness pushrods, to my knowledge these are the biggest that will fit stock heads... I originally wanted to go with 3/8" .135" wall thickness rods until I found out I would have to remove the heads and open them up in order for those to clear, I'm not going through that so the mantons are a good medium between 5/16" and 3/8" pushrods... they are 10% thicker in diameter and 50% thicker wall thickness than the 5/16" .080" chromoly pushrods I had in the car... the guys at manton are awesome, they had my pushrods out the same day and I got them the following day just like they promised... ok enough rambling, here's some pics

the straub trunnion kit



here you can see a clearer shot of the machined flat that supplies oil to the bushings



the bushings and snap rings



manton pushrods





side by side comparison of the mantons (on the right) next to my old 5/16" chromolys... the mantons are also 3 piece, the ends are made separate from the body



the mantons also have a smaller hole for better oil control



passenger side rockers with comp trunnions and 5/16 pushrods before removal



passenger side rockers and pushrods removed



driver side before removal



closer shot of driver side



driver side after removal



at this point I only have it disassembled... as time permits I still need to press out the old comp trunnions, install the straub trunnions, and reassemble everything... I will update this post as things progress... sorry for the lengthy post but hopefully it will be helpful to other members and if anyone has anything to contribute please feel free, after all if it wasn't for me hijacking another thread I might have never known about the issue with comp trunnions to begin with

LoneStarFRC

Pretty sure you'll like those puppies. Easy installation, just same as the Comps.
Nice pushrods as well........ Be sure to post up some pics of your Comp trunnions when you get them removed. In particular, the underside, as that's where the needle bearings exert the greatest pressure. Vehicles with higher open-spring pressures are more susceptible to the excessive trunnion wear that I've seen. My springs are in the 460-480lb range.

Btw, speaking of pushrods, Smith Bros are also now distributors for the Straub RA upgrade kits. Seems they like them as well.

http://www.pushrods.net/trunnion.html

Patches

Manton is just a couple of miles away so I picked mine up from the shop. They do nice work.

I picked up a set of 11/32"/.120" wall like yours with LS7 lifter preload for my setup with HS roller rockers.





Got a free t-shirt

neutron82

that's funny, I had noticed that they were in the same city as you when I was looking for their info... I will definitely be posting pics of the findings of my comp trunnions as soon I get them apart, I'm going to try to get that done tomorrow or Monday hopefully... I'm using pac 1518 beehives so the pressures aren't as high as yours and my cam is quite a bit under .600 lift, I'm not sure if the added cylinder pressure could cause more stress on the rocker trunnions but if it can make pushrods deflect then I don't see why not

vettenuts

From what I have been reading, the bushed bearings (Straub) are quieter than the needle bearings. Also, the larger pushrods are an excellent upgrade. Not sure if you plan any dyno time but I found that my 3/8 double tapers (thread on this here LINK ) smoothed out the dyno curve above 6K RPM.

I called Manton several years back about the 11/32" pushrods. Terry actually called me back from his car and made me one special purpose pushrod that could be easily disassembled so I could play with the length when setting up my engine. Super nice guy, great company and excellent customer service.

Be interested on your thoughts/feedback once its together again and running.

leadfoot4

I'm VERY interested in what you find, when you press the Comp trunions out of you rockers. I, too, installed the Comp kit 3-4 years ago, and thought it would be the "end all" fix, at least for the reasonably easy driving that my car sees. I will say, however, that the bushing kit that CHE was offering, back then, was tempting. Their price of $400 (installed in my rocker arms), as well as the "down time" of my car, while the work was done, turned me off, however.



EDIT...........when I had mine apart, I installed a set of Manley pushrods.

neutron82

after pressing the straub bushings into the new rockers the trunnions feel smoother than the comps did with the needle bearings... I had my car dynoed not too long ago and they let off early, I would be curious to see where it's at when taken all the way up so that would be a good excuse to do it again... sometimes when you do business with a company you can tell who the real car guys are that do this because they love it and the ones that do it to make a few bucks, they definitely strike me as the guys that do it because they love it

well here's what I ended up with... these have about 10k miles on them, they don't look good in my opinion and I'm glad they are out... I kept them in order just to see if there was any type of pattern but the premature wear looks to be all over the place to me... when I popped the trunnions out needle bearings were falling out of the bearing race so they were obviously loosened up... I know there's really no way for them to fall out once installed but it still isn't something you want to see when disassembling them



some close up shots of the damage









close up of the new straub trunnions installed





my only minor gripe about the straub kit, they should include these small washers... it makes the install super easy, luckily I held onto these when I installed the comps years ago



everything is ready to go back in but I'm not so sure about this, the comp trunnions have a recessed area where the bolt goes and the straubs are just flattened out... I don't have the original rocker bolts anymore and it looks like the comp bolts are about 2-3 threads shorter than what they should be when installed... stock bolts show to be 52.5mm long according to a parts catalog and the comps are about 45mm long below the head... I might have to find me a new set of bolts

73Corvette

Nice job documenting your work Neutron82... looks like this might wind up being another STICKY for the tech section.... keep up the good work
What did the needle bearings look like? They have to show some pretty bad wear as well as the trunions... glad you are getting those out before something serious went down

Some of your pics should definitely be in the C5 vette **** section...those trunions are too pretty to install

neutron82

thanks... I didn't get any close up shots of the needle bearings but I still have all the comp parts in my toolbox at work, I can get some next time I'm up there... they are really small though so it might be hard to see but I'm sure they are worn

LoneStarFRC

You were well on your way to complete trunnion failure, not to mention the slowly eroding metal being eaten away from the trunnions, and entering your engine oil. Ungood. Mine were worn a bit more than yours after 14K miles.
Hell, even the factory OE pieces don't have the needles riding directly on the trunnion body.

I wound up reusing my OE r/a bolts. They work fine. Glad to see you got this taken care of.

73Corvette

I'm not sure this is even a word... I love it

vettenuts

If I remember correctly, the first few mm of the stock bolts are not threaded, so the actual engaged thread length may be the same.

leadfoot4

Great pictures! HOWEVER, now I'm concerned that my trunnions might look the same!!

FWIW, and if it helps you at all, I just measured the length of the OE rocker arm bolts from just underneath the "shoulder" of the bolt, to the tip at it's end. It came out at 2.065"......basically 2 and a sixteenth. (I'm a pack-rat, I kept my OE bolts in my "bolt bin", "just in case I ever needed them for something"....)

SuperVetteC5

You got my attention for sure. I just installed the BTR trunion upgrade in my car when I did the cam job. What did the trunion and pushrod set up cost you?

Pounder

What valve springs are you using and do you know the difference of the spring load over stock if you are using other than stock ????? Do you think extra valve spring pressure has a bearing on the wear of the trunnion assembly if your not using stock springs ??? What rpm's do you run ??? Thanks !!

neutron82

2.065" is right on with 52.5mm so the parts catalog I used was correct... I don't remember what the end of the factory bolts looks like but if it is in fact rounded off like vettenuts pointed out then I might be able to use the bolts I have right now... could you check the bolts you have and see if they are rounded at the tip and if so how long is the rounded area?

that sucks... it was right around $400 for everything

I'm using pac 1518's... they are stiffer than stock springs for sure but not as stiff as duals... apparently pac doesn't make them anymore, I can't remember the exact pressures and they aren't listed on their site either... I had considered switching to duals but I was advised to leave them alone if I wasn't getting any valve float, being singles they weigh less... rev limiter is set at 6800, I have considered taking it to 7000 but I'm concerned about the stock rod bolts failing

SuperVetteC5

My stock bolts are rounded just like the pic that VetteNuts showed. Mine are out of a 2004

neutron82

any way you can measure the length of the rounded area?

Rx7Rob

Crapola! Guess I'll be pulling my Comps to take a look. Did you happen to give Comp a call?

How's the weight of the manton push rods?

neutron82

I haven't contacted comp yet but I am thinking about it, I'm curious what they would say... I don't have a proper scale to weigh them but on a bathroom scale the mantons were 3lbs even and my old pushrods were 2.2lbs, this is total weight for all 16... so they are a bit heavier but to my understanding diameter and wall thickness are more important than weight in this case since the pushrods are on the lifter side