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snowman snowman is offline
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Join Date: Feb 2003
Location: So California
Posts: 3,787
If you don't think there is a shop that x rays 100 percent of their product you haven't shopped at SPS. One of the reasons these are the Worlds best bolt is that they are 100% X rayed, thats part of the reason they cost a whopping $25 ea for a typical Porsche rod bolt. These are the EXACT same kind of bolts used in fighter aircraft, where the pilots life depends on it.

If you want to win a race, and you do not do EVERYTHING that can be done you will not win consistantly. And yes Real racers DO use Carillo, it just ain't worth the alternate. Even 99 percent of vintage racers eventually end up with Carillo rods, because the others break and Carillo ones do not.

And yep I am a design engineer, 30 plus years experience, but must state I only have an MSEE not a mechanical degree. But I have done many failure analysis, for space programs, I do know real QC when I see it.

You are wrong about torque. Re torquing a bolt, is bad. Why, not only do you have the unrepeatability of the torque method, which can be off by as much as 100%, even with everything properly calibrated, you burnish the threads each time you tighten them. This means that the next time you apply torque your streatch the bolt even more, how much? as much as another 75 % or more!!!

The stretch method is extreemly accurate in setting the clamping force of the bolt, if you use torque you either are setting the clamping force to small, or streatching the bolt to much, possible breaking it. The maximum force a rod bolt sees is during tightening. ONce this has happened, its guarenteed to hold that much, by definition enough for all running conditions. HOw is this inferior to over or under tightening a bolt??

SPS makes a range of rod bolts for Porsche type rods. Only a Carillo rod can take advantage of the full capability of the rod bolts. Thats because the ROD must be designed to work with the bolt. Porsche ones (at least production ones ) are not. And only SPS makes rod bolts t hat can do 320,000 psi.
Contact SPS for info on these special materials. By the way its usually not the rod that fails,its the fastener. But they are interelated.
Here are some additional links

http://www.carrilloind.com/pdfs/10777_eprint.pdf

http://www.machinedesign.com/ASP/strArticleID/14487/strSite/MDSite/viewSelectedArticle.asp

Last edited by snowman; 03-29-2004 at 10:27 PM..
Old 03-29-2004, 09:42 PM
  Pelican Parts Technical Article Directory    Reply With Quote #42 (permalink)