----- Original Message ----- From: <tobyp@xxxx> To: <dmcnews@xxxxxxxxxxxxxxx> Sent: Tuesday, November 13, 2001 12:52 AM Subject: [DML] Re: Trailing Arm Bolts - Engineering > David - You are quite correct in your assessment that the tubes and > sleeves will collapse if the torque is increased significantly. I > installed the new bolts at a torque level of 50 ft-lbs, with a > copper-based anti-seize compound applied to the shank and threads. > That is the same value as the "stock bolts" as I recall. Forgive me, > but I ran some numbers today on the preload in the bolts caused by the > installation torque. I wanted to see how much tensile stress we put > on the bolts by torqueing to that level. It revealed some interesting > information ... without going into the calculations in detail, a > torque of 50 ft-lbs on the TAB with grease on the threads and shank > would create a tensile (tension) stress of about 116 KSI. (Remember > that 1 KSI = 1,000 PSI). If the threads on the bolt and nut are > perfectly clean and dry, the tensile stress value at 50 ft-lbs of > torque is 48.3 KSI. Trust me on this ... it just works out that way. > The actual preload is probably somewhere in between those two > extremes, but it varies depending on the cleanliness of the hardware. > The average of the two is about 82 KSI. If you are brave enough to > muscle through a previous post of mine, the maximum allowable tensile > yield stress on the stock bolts is 103 KSI. We are probably coming > close to yielding, or stretching, the TAB every time it is torqued. > The variation could also explain why some people have a problem with > their TAB's , and others do not. My custom bolts have an allowable > tensile yield stress of 200 KSI, so they would only get to about 1/2 > of their capability at maximum torque. Okay ... I'm done. I just > thought that you'd like to know. > > BTW - What are some of these other solutions that vendors have come up > with? I haven't seen "The Fix" for this area yet ... just a lot of > hand-wringing, and guessing. Please advise. > > > --- In dmcnews@xxxx, jtrealty@xxxx wrote: > > All of what you wrote was interesting but it comes down to putting > > more stress on the bolt then it will see in service by torquing it > > above that level. If you go overboard you will collapse the metal > > spacer in the radius arm bushing pn 106716. As is usually the case > you > > cannot improve an entire system by changing one part. It usually > takes > > a reengineering of the entire system or you just move the weak point > > to somewhere else in the system. Before you continue you should > > discuss this with a Delorean vender as they have all "been > there-done > > that" and now have a good way to fix this weak area. There is no > > substitute for experience so before starting on a new project like > > this you should get all of the history that you can. > > David Teitelbaum > > vin 10757 > > > > > To address comments privately to the moderating team, please address: > moderator@xxxx > > To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > >