Stainless fastening grade
Turbo Mini Forums

hello,

Would A2 grade stainless fastenings be ok for stuff like gearbox to block bolts.

saw some on ebay for a reasonable price,

http://cgi.ebay.co.uk/Stainless-UNF-Allen-...1QQcmdZViewItem

arnt all the fasteners on the gearbox UNC and not UNF?

I've seen the future and tbh its Pie

yeah but the ones that go into the block from the gearbox will be UNF.

i've had my eye on those same cap heads for quite a while now aswell

Yep any thing screwed into ally is UNC, anything into steel ect is UNF, but the link was just an example as they do a load of stuff, like mixed size packs.

I'll get some mixed stuff for general use, but just wondered about use in higher stress places.

I have heard bad things about stainless fixings used in highly stressed areas. I am gonna use a good quality Cap head bolt as the strength on them is far better than any 8.8 spec bolt. Or if you are that way inclined you want to use NAS aircraft bolts!!! only £20 a pop!

for high stress areas such as gearbox to block use 12.9 cap head bolts. Not stainless as they are too brittle.
Stainless can be used in low stress positions without a major problem as long as they are good quality. Should be fine in places like thermostat housings, manifolds etc.
I'm currently sorting my fasteners at the moment. I may start supplying kits for things like the gearbox mountings etc.

You don't want allen head bolts there, as they are a nag to tighten. That's on the front side. On the rear it's IMPOSSIBLE to use allen headed ones. At least four-five of them.

They're not an arse to tighten if you have a 'wobble head' allen key...

I use unbrako cap-heads (allen key) bolts in all mine - no problems.

- oh, there is one stud at the back i recall - over the diff housing. Couldn't get it in there.



- or have i just imagined that... I know i had a single stud once - but found last year that i could get a cut-down cap-head in above the diff...


edited again - yes, pretty sure that was the case... It had about 3/8 thread engagement into the block, but that's better than full engagement with a putty-steel stud...

Edited by turbodave16v on 2nd Nov, 2005.

I used high tensile 1/4" UNF sets on my engine, had no problem getting them in to ALL of the block-to-box threads with full engagement into the block side..........

Thought that was the case

don't suppose you have the lengths to hand that you use so i can just go get myself some?

Unbrako is what i will be using if this place i use sells them, if not 12.9's will have to do. Sure they'll be fine.

Stainless OK for corrosion A2 chepo

A4 better resistance to corrosion

there not that strong!

having said that there more than a match for going into cast blocks

but I would go with zinc plated 12.9 grade fasteners peace of mind