13 replies to this topic

[Gedi]

I'm replacing my brake caliper to hub bolts but am unsure which spec bolts to use.

 

They're low head cap heads from the AP big brake kit (M10 x 30), but the AP spec sheet doesn't state whether I should be using 8.8 or 10.9 bolts.

I'd assume 10.9, but I'm having trouble finding some. I have however found some 8.8 bolts...

 

http://www.ebay.co.u...=item43c967b746

[p4cks]

I've just ordered these from eBay "Cap Head Allen Socket Bolt M10 X 65mm Black 12.9, Pack 1 to 8"

 

 

 

 

[Gedi]

I need low head bolts though. Also I'm not sure if 12.9 is too hard for the brake callipers. AP really need better spec sheets...

[p4cks]

They don't tell you the spec intentionally because they don't want you replacing them yourself

[p4cks]

(sh*t sorry just realised you said the big brake kit in your OP, the ones I linked are for the standard APs)

[Rosssco]

Just buy these:

 

http://www.elisepart...-caliper-bolts/

 

Or maybe you need longer bolts:

 

https://www.elisepar...-caliper-bolts/

 

Be careful using higher grade bolts - you need to use the corresponding increased bolt torque. If you don't, you've not preloaded them properly.

Edited by Rosssco, 07 October 2015 - 07:13 PM.

[Gedi]

The bolts you linked to are for holding the two halfs of the calliper together.

What I'm looking for are the bolts that hold the calliper onto the hub, which are M10 x 30 and have a low head.

 

No 9 in this pic are the low head bolts, and No 10 are the regular bolts. 

https://onedrive.liv...ithint=file,pdf

 

As I don't know the spec, I don't know which grade to replace them with and as you say, whether the 58NM is correct.

I wouldn't normally worry too much, but with the brakes I wanna make sure everything is right.

[Rosssco]

The bolts you linked to are for holding the two halfs of the calliper together.

 

 

If so, then why are they sold stating different brake disc diameters? Shirley they would reference brake disc thinknesses if anything then...?

 

I'm pretty sure they are the radial mounting bolts, with the longer version available if you are using radial spacers to move the caliper further out for different disc sizes..

 

Not sure if they are suitable for the AP 4pots, but given the calipers are often a direct replacement, might be worth an ask to EP...

 

Google torque chart indicates that standard bolts are Gr.8.8 -

 

[NOSBandit]

I just fitted new bolts to my 4 pots and elise parts supplied 8.8 as these were the grade that was recommended by lotus

[NOSBandit]

Torque was 45nm

[Gedi]

I'm pretty sure they are the radial mounting bolts, with the longer version available if you are using radial spacers to move the caliper further out for different disc sizes..

 
Yeah you're probably right. They looked far too long when compared to the 4 pot bolts, but it's been many years since I've laid eyes on the 2 pot calliper
 

Google torque chart indicates that standard bolts are Gr.8.8 -
 

That's a great chart, thanks for sharing. It gives me some confidence that the 8.8 is the correct spec (which is lucky because it's the only one I can find in a low head )

Edited by Gedi, 08 October 2015 - 06:35 AM.

[Gedi]

Torque was 45nm

 

Are you sure about that? The AP parts list I linked to states 58NM.

AP did change the design to drop the mounting plates though, which I think are the only ones EP have ever sold. Not sure if they lowered the torque value for the new design?

[NOSBandit]

If they are grade 8.8 the torque would be 45nm. 58nm sounds like grade 10.9. When I spoke to EP they recommended 8.8 only for the 4 pot calipers as the 8.8 would flex a little where the 10.9 are more brittle and could snap. I hope they are right as I have just fitted 8.8 to my brakes after there recommendations.

[Gedi]

According to the chart Ross posted, 58NM falls into the 8.8 spec (although right on the top limit) and is below the 10.9 spec.

Admittedly it falls right in the middle of the 9.8 spec, but they're not a common spec.

 

AP's fitting instructions here state:

 

Torque each caliper socket cap head fixing bolt to the torque identified in the Kit specific Publication P12.

And here is the P12 which state 58NM https://www.apracing...ings/p12170.pdf

 

Here's AP's page regarding the (original / TMS) VX big brake kit https://www.apracing...p7621-1001.aspx