I'm trying to roll my own device mount to attach to the back of the tach like so many have done before me. I'm attaching my bracket to the back of the tach using the existing holes, but the screws are about 5/8" too short. My research shows that these type of screws are called 'plastite' screws, and that I need them to be about 1-1/4" long. But I can't find any way of measuring the threads, so I'm having trouble locating the right ones. Has anyone found a source for these and/or know what the thread size of the existing screws are? Note that I'm not talking about the vertically-mounted, torx screws that attach the tach to the steering column - I'm trying to find the phillips headed screws that screw into the plastic back of the tach itself.
Don't know the pitch either but if you figure that out the place to look is McMaster-Carr or smallparts.com.
Yeah.... I had to go with longer screws when I made my own gauge bracket (for additional pic's, go to my garage). I also used the same three mounting points on the tach gauge. I found a "Truss Head" sheet-metal screw was the same. I'll let you know the size tomorrow when I'm at work (I'm thinking it was a #8 screw), but I'll verify it for you..... http://www.motoringalliance.com/forums/interior/1954-new-mini-gauges-2nd-gen-3.html#post67719
It was a weird thread pitch on my '06, but the metal is somewhat soft. You can just get a screw the right length and run it in there; it'll hold.
Yeah, here ya go.... It's a #8 Truss head sheetmetal screw. These are "Thread Forming" screws. And at least in my case with the R56, the three holes were in a white plastic, not a soft metal. They worked just fine with matching the stock threads in the tach housing. Mine were SS, you may need to paint yours if you want black. P/M me your address and I'll be happy to throw these in an envelope for you, if you can't find them locally.
Oops, my bad, I didn't read down far enough. The vertical torx screws are M5x1.25, which is an answer to the question the OP didn't ask. :frown2: Hehe, yeah, I'm giving the profession a bad name. If I've learned anything, though, it's that the best solution isn't always the most correct.
OP has a first gen......will these work? To the OP, you might give Kellen at Cravenspeed a call as they supply new screws for their mount.
#8-16 sounds like the right size. This is the best picture I could get of the threads. The sheet metal screws I compared to all seemed to have a larger shank diameter, so I wasn't sure they would fit.
# 8 is right, I just went to the local hardware store, with the original as an example. I got a plastic box of stainless steel screws with the same pitch, but they were an inch and a quarter long, I cut it down and smoothed the end on a grinder. It screwed right in, no problems. Dave
Either I got different #8 sheet metal screws or the R56 is different from the R52. The threads are just different enough (smaller?) that they don't mesh and it binds in the hole after about 1-2 turns...
I just checked. R56 and R52 tachs use the same screws (I happen to have both handy from my work on InvisiLens).
I do remember the same slight resistance and when I measured the two screws, the #8 had a slightly larger root diameter but the threads were right on. Remember, these are thread forming screws. When they were originally installed at the factory the screws formed the threads at the time they were inserted. The #8 is doing something similar. The threads are matching but there is slight resistance with the #8 due to the slightly larger root diameter. I have even re-installed the original screws and they continue to work fine. Just make sure about your length.
Do you remember the size and type you got? Do you agree with the consensus so far of the #8 sheet metal screw or did you find something that fit better?