AP Bell thickness & OEM bolts

[daniel]

Hi,

Just fitted a set of AP brakes:thumbs: and have encountered a problem with the bolt lengths. It looks like the AP bells are thicker than the OEM disc bells and now I can only get approx 3.75 turns (hand tight) on the oem bolts before having to torque them up. Does anybody know the exact thickness difference between the two as I didn't manage to measure them.

And for those with APs are you using the standard bolts?

Thanks

[shimmy]

Hi,

Just fitted a set of AP brakes:thumbs: and have encountered a problem with the bolt lengths. It looks like the AP bells are thicker than the OEM disc bells and now I can only get approx 3.75 turns (hand tight) on the oem bolts before having to torque them up. Does anybody know the exact thickness difference between the two as I didn't manage to measure them.

And for those with APs are you using the standard bolts?

Thanks

I think all AP kits come with AP bells and AP bolts. You may need to buy the bells.

[daniel]

I have the whole kit and it is mounted, but the bells are thicker which pushes the wheel further out.

Haven't you noticed this?

[s.mac]

And for those with APs are you using the standard bolts?


Im on standard bolts and not noticed anything :)

[daniel]

Im on standard bolts and not noticed anything :)

Do you know how many turns you are getting on the bolts?

[_Nathan_]

I used standard bolts too before moving to studs.

[shimmy]

I have the whole kit and it is mounted, but the bells are thicker which pushes the wheel further out.

Haven't you noticed this?

Sorry I thought you meant bell bolts, not wheel bolts.

The standard bolts should fit, mine do. The two locating grub screws should fit flush and tge locating pins also sit flush. If they don't then you either haven't mounted it properly or have been given the wrong bells.

[s.mac]

Do you know how many turns you are getting on the bolts?

no sorry but Im sure its more than you're getting, If I remember I will check tomorrow

[daniel]

Sorry I thought you meant bell bolts, not wheel bolts.

The standard bolts should fit, mine do. The two locating grub screws should fit flush and tge locating pins also sit flush. If they don't then you either haven't mounted it properly or have been given the wrong bells.


I have CR2494-1589 stamped on one of them. Does that tell you anything?

[shimmy]

No, haven't got the catalogue.

Could it be CP2494-1589?

[daniel]

No, haven't got the catalogue.

Could it be CP2494-1589?


Yeah, should be CP. Wasn't very clear.

[shimmy]

Yeah, should be CP. Wasn't very clear.

Check the 1589 as it seems wrong as well

[daniel]

Strange. It is these ones http://www.cslregister.com/forum/showthread.php?t=5169 and the number does appear to be CP2494-1589. What should it be?

I have just measured the oems disc through the bolt holes to the best of my ability and they appear to be approx 7.5-8mm.

[shimmy]

Daniel

Just read your post again

I think you are on about the disc bolts after all. You should be using AP bolt kit to connect the AP disc to the AP bell. New locking nut/bolt set torques to 14Nm.

Don't use the old BMW ones as like you say fitment is totally different.

[daniel]

Hi Shimmy,

Think I wasn't that clear. I am talking about the disc surface that bolts to the cars hub, I think the AP is thicker at this point which effetively pushes the wheel further out. And as the wheel bolts to the hub through the disc the bolt feels shorter.

Hope this helps.

[shimmy]

Hi Shimmy,

Think I wasn't that clear. I am talking about the disc surface that bolts to the cars hub, I think the AP is thicker at this point which effetively pushes the wheel further out. And as the wheel bolts to the hub through the disc the bolt feels shorter.

Hope this helps.

In that case either it is the wrong bell or you are not mounting it correctly flush.

Do the locating steel pins line up with the holes and end up flush. Is the bell sitting back touching the hub?

[cantfind1]

Hi Daniel. I know exactly what you are talking about. Even if Shimmy is being a bit slow!:gayfight:

I have the same issue with mine, the standard wheel bolts were too short, yes only 3 and a bit turns after fitting the AP discs and bells. I just went and bought longer bolts as I was fitting 10mm spacers as well.

I think the standard bolts are 25mm so you may need an extra 5mm or so think they come in a 32mm or maybe 30mm.

I never got around to measuring the AP bell thickness or the oem bell thickness but I assume the AP bell was a little thicker and that's where the problem is. Not sure if they are all like this?

My solution was fit longer wheel bolts!

[daniel]

Hi Daniel. I know exactly what you are talking about. Even if Shimmy is being a bit slow!:gayfight:

I have the same issue with mine, the standard wheel bolts were too short, yes only 3 and a bit turns after fitting the AP discs and bells. I just went and bought longer bolts as I was fitting 10mm spacers as well.

I think the standard bolts are 25mm so you may need an extra 5mm or so think they come in a 32mm or maybe 30mm.

I never got around to measuring the AP bell thickness or the oem bell thickness but I assume the AP bell was a little thicker and that's where the problem is. Not sure if they are all like this?

My solution was fit longer wheel bolts!

Thanks:thumbs:Good man. Was doubting myself and wondering if any of it had to do with my wheels being refurbed etc. AP confirmed this morning that the AP bell are 2.5mm thicker than standard so longer bolts are needed. I had a bit of a juggling act with bolts last night and ending up having to stick +12mm bolts on the front wheels which do protrude from the rear of the hub a couple mm. Need to get a +4/5mm bolt now.

[glendog74]

Are standard OEM M3 brake callipers not different to standard OEM CSL brake callipers? Could explain different dimensions?

Ignore me if i'm talking poo :hahaha:

[shimmy]

Doubt it matters much, I've done 60k miles with AP and standard bolts in track and never come loose.:whistle:

[glendog74]

Standard bolt length on mine too - no problems. :thumbs:

[daniel]

With how many turns?

[DuncanR]

As a general guide,you should be looking to get 1.5 x thread diameter of engagement in a tapped hole, but as this is a through hole, at least engage the full thickness of the bell HOWEVER beware as if you fit bolts that are too long, they will foul your backplate, and if one of your lads tasked with changing the wheels fails to notice the spacer is stuck to the inside of the wheel, and then fits tother wheel without said spacer and with long bolts, and you drive off...it fooks the backplate !:banghead:

[s.mac]

I just got half a dozen full turns before I started with the wrench