XR4Ti Archived Tech Articles
Post Date: Fri, 20 Jul 2001 Subject: Re: Turbo to manifold mounting problems Exhaust Question List: email@example.com Andrew wrote: > I am having a really hard time keeping the > nuts from backing of the turbo mounting studs. I suspect you replaced the nuts with a non-mechanical locking fastener when you put everything back together. The original nuts where of the prevailing torque type with either stoverized or crownlock tops. This means that the top of the nut has been slightly reshaped to deform the inner threaded section. It works similar to the more obvious and familiar 'nylock' nut, with the nylon insert. If you look at the top of the nut, you should see that the opening has a slightly oval shape and areas where the top of the nut have been squeezed or there are three stamping marks (typically) on the top of the nut. We have some interesting fasteners on our XRs (if you're in to that kind of thing). The exhaust manifold to head bolts are of locking design too. The cross section of the minor diameter (the valley of the threads, so to speak) is not a circle. It's sort of like a really rounded off triangle (often refered to as a 'tri-roll' in the fastener industry). If you look at one of these bolts you'll see high points of the rounded off triangle if you notice where there is shiny metal in the minor diameter. It's things like this that make it difficult to replace some of our fasteners. It also requires that you pay a little attention sometimes. For example, I almost ran a die up and down all the exhaust manifold bolts before I put things back together this week, until I noticed that the threads looked a little odd.Back to the Tech Articles main page
Published by Chris Anglin.