LMER

Hi,

when adjusting the TPS voltage on my -86, I broke one of the two aluminium torx screws that holds the TPS. Does anyone know the thread size of those screws?



Best regards

AGENT 86

It's a bastard size if i remember correctly. I drilled and retapped to the next AVAILABLE size and used stainless allen heads.

Corvette Kid

Really small! I'm heading out to the garage in a few minutes. I'll check one and let you know.

LMER

Could just imagine that! I'm from Sweden and not very familiar with inch sizes, but I couldn't find anything with the same size in different stores even though they were specialized in screws, of course most metric but also some inch-sized.

LMER

Waiting...

Corvette Kid

It doesn't match up to anything on my thread pitch gauge. Unfortunately I don't a metric gauge here at home. Also I don't have any metric taps and dies that small to match it against here at home either. If you're in a bind, I can send you a screw. I have several TBs lying around.

LMER

Strange, it seems to be something like M4.5 which is an existing size but rarely used, i.e. I've never seen it in use. Isn't it very odd that they use something that unusual, metric or inch, on a standard engine? I was told that all engine screws are inch-sized. Do you have another opinion?

Thanks for the offer, but I can't let you go through the hazzle to send a screw to Sweden.

I'll just tap it to the next metric size and put stainless screws there. I have some work to do during the winter anyway: New leather seat covers, new suspension bushings and new shocks, all ordered from Ecklers today. That'll keep me busy for a couple of dark winter evenings

Corvette Kid

4.5mm and/or 3/16" is about what it measured too, using my fractional calipers. But I'm sure it's metric since the AS pitch gauge showed no match. Actually there are quite a few metric bolts on these engines. It's mainly the bolts that thread into the block and head castings that are American Standard, since these basic casting designs have been around for over 50 years. It sounds as if you've got things under control then.

AGENT 86

Yes it is M4.5, a rare bastard

LMER

Thanks guys!

Of all dimensions, why not use an extremely rare one... Sometimes you wonder... That designer must have had a very bad day!!!

AGENT 86

It's bad enough that they used aluminum screws
Then add an oddball pitch
Oh, and lets mix standard and metric all over the car