High Tensile, mains bolts
Turbo Mini Forums

i got my cms kit this month from minispares and got a 3dash and a 6dash in the same sealed packet one is 6mm longer that the other aswell
ive got some on the way from carl

Yes i moved to the darkside

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put it together without a strap in the end colin .:$ totally failed . but she'll have a strict 6k rev limit , on a 1098 .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I think its only a matter of time, they just don't fail the instant you start using the engine.

Look at this way, if you are deciding to fit a strap, the engine is likely to be stressed more than standard. using a grade 5 bolt, in this aplication is a backwards step since the standard bolts are a grade 8. It follows suit that if you increase the stress in an engine, that you should at least increase the quality of the bolts that hold it all together, and likely to hold it all together for longer than the bolts will be in use. Take for instance the big end bolts. Would you use a lesser grade bolt in that aplication? Not me!

Other things to consider, is how long the bolt is used for. Austin Rover group specified a bolt that would last longer than the life of the engine, without failure. The old 'Textbook Of Good Practice, page 1' says that critical bolts should be replaced when an engine is rebuilt. Perhaps these tuning companies are using this theory when they decide to use a lesser grade bolt than the factory application, such that a highly stressed engine is going to have a rebuild long before fatigue life of the bolt, when new ones will be fitted.

That at least is what I would like to think these companies were considering when specifying a grade 5 instead of a grade 8. This has one major flaw.

Yea i'm of the same thinking sprocket, totally agree. I only ask as i have just recently finished a build using the aformentioned strap and it did bother me when i noticed the grade 5 bolts.
I enquired with local stockists for some grade 8 or higher bolts at the time which was unfruitful.

So in a hope to aleviate my worries i contacted MS and i was told they had heard of no failures on customers cars or their own cars so the strap ended up being fitted. The engine is now in the car but has not been run yet so i'm in a bit of a dilema again now as to what to do...

In addition, if you fit a lower grade bolt (with a lower UTS) and torque it to the setting specified for the higher grade bolt, it will be taken to a much higher percentage of yield strength - and that's before any service loads are applied.
Depending on what percentage of yield the designer chose for the high grade bolt, the lower grade may even begin to yield just by being torqued up.

Schrödinger's cat - so which one am I ???

I respect the guys at Minispares, as they clearly deal with Minis day in day out and for some, most likely at the weekends and evenings too. But, to sell a lesser grade bolt than the factory production item, and then turn round and say its ok because we have not 'heard' of any failures of these bolts, is a little careless In My Opinion. Which is why I supose Gavin took the initiative and hopefully sorted the issue out, but going from what I read in this topic recently, is not quite the case.

rather new here...

So correct me if i am wrong. When i'm using the 2 bolt mainstrap, i will need (4x) 7/16-20 (743-2750) and 2x 7/16-20 (743-3500)

thanx

Sorry only just read your post Sprocket, i pulled all the cms's off the shelf and had all the bolts changed to grade 8 a while back. Brett i can only assume one has slipped through, if you pm me your address i'll get you some bolts in the post.

pm'd

Yes i moved to the darkside

Instagram @jdm_brett

rather new here...

So correct me if i am wrong. When i'm using the 2 bolt mainstrap, will i need (4x) 7/16-20 (743-2750) and 2x 7/16-20 (743-3500) ????

thanx

you need 4 standard bolts for the 1st and 3rd bearing cap and the longer ones for the centre cap, they need to be the same length as the standard PLUS the thicknes of the strap if you buy a strap kit from minispares, everything needed comes,
and as gavin says they are all sorted out and the stronger bolts are now supplied

Yes i moved to the darkside

Instagram @jdm_brett

Ok thanx. I will order a new strap (and 4 new bolts For the 1st and the 3th at spares. Is it wise to mount the new bolts with ARP hardend washers ????
thanx

on the centre strap?.. yes, im using washers, for the other 2 just use as standard

Yes i moved to the darkside

Instagram @jdm_brett

From the looks of it Gav, you've not made any of the changes we suggested for the website

Carl, still got some of those bolts? I need a couple for the last engine build ever with a strap

WTF!!

http://www.theminiforum.co.uk/forums/index...howtopic=172522

Yes i moved to the darkside

Instagram @jdm_brett

I supose they knew about this long before anyone else and sold the 'correct' grade bolts before everyone else and it is their moral rights that are beeing abused?

funny mra pushing that info

a few years back they were selling stainless 'towing eyes' with were actually just boat deck fittings, and would have in no way been fit/safe for the forces involved in towing

interesting eh

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