Bolts of Doom, are they grade 8.8?

[IainP]

As title really, would anyone know if the bolts for the push rods, the bolts of doom, are grade 8.8?

Iain

 

[Stevo7682]

What are you describing as a push rod ?

Stephen

 

[t-tony]

It's the proper name for the brackets at the bottom of the rear beam mounts Steve, God knows why.

Tony.

 

[IainP]

Yeah, these, I presume it’s a translation from German

part 4
I’m assuming/hoping the bolts are only 8.8 due to the way they chewed up. I can replace with A4 stainless. If by some chance they’re 10.9 I can’t.

 

[Stevo7682]

Thats what i thought he was talking about Tony just thename didn't fit.

@Scooblitz may have the answer he had to get replacements when i did his back end rebuild.
If memory serves the original bols are no longer available so we ended up getting bolts with 13mm heads of the same grade as original.
Stephen.

 

[Stevo7682]

See at the end of the day as long as you use a decent grade they will be fine .
If the rear subframe bushes are in good condition strictly speaking the push rod plates don't take that much load on them .

Stephen.

 

[Althulas]

I used some zinc flanged bolts off eBay. I’m can’t recall if I used 10.9 or 8.8 though.

I’ve bought quite a lot of hardware from eBay in either zinc or A4 stainless (=8.8 strength) mainly as it worked out cheaper then buying from the dealer. Sourced from Bolt World, kays,a2zfast65, boltbase and

8.8

FLANGED HEXAGON BOLTS HIGH TENSILE 8.8 PLATED STEEL FLANGE HEX SCREWS M6 M8 | eBay

Find many great new & used options and get the best deals for FLANGED HEXAGON BOLTS HIGH TENSILE 8.8 PLATED STEEL FLANGE HEX SCREWS M6 M8 at the best online prices at eBay! Free delivery for many products.

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10.9 (apologies from china couldn’t see a uk seller in zinc in std pitch)

Pardon our interruption...

Just check the thread on your bolts as I can’t recall if the pitch is standard or fine.

 

[IainP]

Thanks folks, I have A4 and flanged 8.8 of correct pitch. I’ll bung in the A4 when I build it back up. Just feverishly over thinking it.
Iain

 

[Scooblitz]

I used a set of 10.9 tensile bolts from www.accu.co.uk

 

[Jack Ratt]

Generic A4 stainless fasteners are NOT the same tensile strength as 8.8 steel bolts.

Generally, if a fastener is just marked A4 it's tensile strength will be classed as 50kg/mm2 which is comparable with mild steel.

High strength A4 fasteners are available and will be marked as A4-7 or A4-8.

A4-8 is on par with 8.8 strength wise but it's yield point, ie, the load at which the bolt starts to stretch is lower.

8.8 steel will yield at around 80% of ultimate tensile strength, whereas A4-8 stainless yields at around 60% of ultimate tensile strength.

This is important when tightening to correct torque value because if you torque an A4-8 stainless bolt to the same torque value as 8.8 steel bolt you may be very close to it's failure point.

 

[IainP]

Thanks Guys.

 

[DomiMik]

The original bolts are 10.9, should be visible on the bolts if they aren't too much corroded.

I can recommend these bolts from VW / Audi, same dimensions and same grade but their head is quite useful as it is both hexagon and torx, part number WHT003252.

 

[IainP]

Cheers, exactly what I wanted to know

Those were the two best ones, nothing visible.
I should have some 10.9 in the depths, if not I’ll order those.
Thansk for that.

 

[Andyboy]

The original bolts are 10.9, should be visible on the bolts if they aren't too much corroded.

I can recommend these bolts from VW / Audi, same dimensions and same grade but their head is quite useful as it is both hexagon and torx, part number WHT003252.

View attachment 253247

These and some copper grease.

I had a fight to the death with these on an E36 Compact recently.

 

[IainP]

Always, I keep a big tub with a paint brush in it, everything except nylocs gets greased.

 

[Andyboy]

These however are nothing compared to the transmission tunnel brace bolts on E90's, 1 Series etc. They were 13mm and around 2007 some genius decided torx bolts were better. You try getting those out after 10-15 years.

 

[IainP]

The manufacturer only cares about how quickly they can build them I think

 

[Althulas]

Generic A4 stainless fasteners are NOT the same tensile strength as 8.8 steel bolts.

Generally, if a fastener is just marked A4 it's tensile strength will be classed as 50kg/mm2 which is comparable with mild steel.

High strength A4 fasteners are available and will be marked as A4-7 or A4-8.

A4-8 is on par with 8.8 strength wise but it's yield point, ie, the load at which the bolt starts to stretch is lower.

8.8 steel will yield at around 80% of ultimate tensile strength, whereas A4-8 stainless yields at around 60% of ultimate tensile strength.

This is important when tightening to correct torque value because if you torque an A4-8 stainless bolt to the same torque value as 8.8 steel bolt you may be very close to it's failure point.

Thanks for the correction of the information I was given. Fortunately I have not used any of those bolts in a load application.

 

[Matt Barnes]

I used some zinc flanged bolts off eBay. I’m can’t recall if I used 10.9 or 8.8 though.

I’ve bought quite a lot of hardware from eBay in either zinc or A4 stainless (=8.8 strength) mainly as it worked out cheaper then buying from the dealer. Sourced from Bolt World, kays,a2zfast65, boltbase and

8.8

FLANGED HEXAGON BOLTS HIGH TENSILE 8.8 PLATED STEEL FLANGE HEX SCREWS M6 M8 | eBay

Find many great new & used options and get the best deals for FLANGED HEXAGON BOLTS HIGH TENSILE 8.8 PLATED STEEL FLANGE HEX SCREWS M6 M8 at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

10.9 (apologies from china couldn’t see a uk seller in zinc in std pitch)

Pardon our interruption...

Just check the thread on your bolts as I can’t recall if the pitch is standard or fine.

Not sure if it's myth or not... but I was practicing some zinc plating and I read somewhere that anything high tensile should not be plated due to "hydrogen embrittlement".... has anyone experienced zinc plated bolts shearing ?

 

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