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Brake Caliper Re-Furb


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#1 krev2_1

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Posted 15 May 2020 - 04:50 PM

Hi

 

I have a set of 8.4" AP (lockheed) calipers that i'm re-furbing

 

Does anyone know what size of screw/ bolt the following are:

 

The plug next to the bleed nipple, this seems to have a point 

the bolts holding the 2 half calipers together

 

Thanks in advance 


Edited by krev2_1, 15 May 2020 - 04:50 PM.


#2 I hate Brian

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Posted 15 May 2020 - 05:54 PM

Hi are these just normal 2 piston calipers ?



#3 krev2_1

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Posted 15 May 2020 - 06:07 PM

yeah, just the normal 2 piston ones made by lockheed 



#4 Moke Spider

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Posted 15 May 2020 - 08:01 PM

The Bleed Nipple and that Plug are 3/8" UNF.  I don't know of a source for the plugs, but a Brake Shop would help here. They are not odd ball or unique to the Mini. Another option here is to fit a bleed nipple.

 

The threads for the Bolts are 7/16" UNF and they are a Grade 8. I don't have a length of them to hand.



#5 krev2_1

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Posted 18 May 2020 - 01:54 PM

thanks Moke. 

 

Seem to get mixed messages about a brake re-furb. Some say dont do it. Some say its fine. Whats the consensus on this forum ? 

 

I have replaced all the seals and even the small o-ring between the caliper halves. 

 

Does any one have a torque figure for the bolts? 



#6 Moke Spider

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Posted 18 May 2020 - 08:42 PM

Most workshop manuals cover the refurbishment and they usually include a caution note not to split the Caliper halves.

 

AP issue similar advice, however, they do also say that if you do wish to split them, then replace the Bridge Seal and the Bolts. The reason they initially don't recommend splitting them is because the other parts (seal and bolts) aren't included in their standard overhaul kits :blink:

 

I'll add though, that while this here ^ is the official advice and really, what one should follow, I have on occasion split them and reused the bridge seals and bolts. 

 

Personally, I do prefer to always split them to overhaul them. They are easier to strip apart, you can really clean them up - there's a few nooks and cranies that the dead sea, cows and sheep will reside in and you'll see this if you do split them. I also find it's much easier to get the wiper retainers in too.



#7 GraemeC

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Posted 19 May 2020 - 02:13 AM

And the reason they say to replace the bolts is because the originals were a nyloc type, but thread lock will do the job.



#8 krev2_1

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Posted 19 May 2020 - 07:18 AM

Thanks All, so it seems like splitting them is fairly common, and not completely unheard of. 

 

Does anyone have a source for the bolts for the caliper half.... I'm struggling to find some of a similar size. 

 

Although when I spoke to minispares they said I shouldn't have split them and I should use the existing bolts. 



#9 Moke Spider

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Posted 19 May 2020 - 08:33 AM

Does anyone have a source for the bolts for the caliper half.... I'm struggling to find some of a similar size.

 

They are a 7/16" UNF Grade 8 Bolt. I don't have the length to hand.

 

I'll just mention a word of caution here, given that there's so much questionable stuff around these days that when buying them, be sure that they are Grade 8 Bolts and not substandard. I can't offer much here in the way of guidance as to how to pick substandard fasteners, it's a huge headache. About all I can suggest it to buy from a reputable engineering suppliers. You could also use the likes of an Unbrako Brand Cap Head Bolt or ARP Fasteners or, as many of us have done, re-use the original fasteners if they are in good order.



#10 g0myw

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Posted 19 May 2020 - 08:35 AM

I was in your situation [winter brake overhaul]
also unable to find the bolts - although didnt try too hard to find them.
I've no qualms splitting calipers [motorbikes or cars]
As said above it makes the cleaning overhaul process much easier.
the 'split O ring / seal' is readily available.
Somewhere in this forum is the recomended torque for bolting the 2 halves.

#11 MaximMini

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Posted 19 May 2020 - 08:47 AM

Hi g0myw,

 

You may find some useful information here:

 

http://www.theminifo...es-bolt-torque/

 

and here:

 

http://www.theminifo...reconditioning/



#12 Tomm

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Posted 19 May 2020 - 08:52 AM

I am currently weighing up my options of replacing or refurbishing my 7.5 calipers and have misplaced the caliper bolts. I suspected they would be easy to locate but had never looked. Your thread has got me looking now.

The 7.5” half bolts and bridging washer seem to be readily available.

https://www.minispar...ic/17H8765.aspx

But when I look for them in 8.4” it says NLA. Shown by item 6 in this diagram.

http://www.minispare...s.aspx?2~17~139

Is there any chance they’re interchangeable between the two? I had about 3/4 sets of 8.4” calipers but threw them all away. Would be helpful if someone has possibly dismantled a caliper and can give us some ideas on shoulder and overall length.

#13 GraemeC

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Posted 19 May 2020 - 09:21 AM

A quick Google search on the part number for the 8.4" bolt gives this:

http://www.somerford...roducts_id=3693

and this:

https://mgbhive.co.u...er-bridge-bolt/



#14 Tomm

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Posted 19 May 2020 - 09:24 AM

A quick Google search on the part number for the 8.4" bolt gives this:

http://www.somerford...roducts_id=3693

and this:

https://mgbhive.co.u...er-bridge-bolt/

 

 Result Graeme. Was that googling the part number listed by Minispares? 



#15 GraemeC

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Posted 19 May 2020 - 10:01 AM

Yes.

 

I must admit I was confused by your question - you mentioned needing the bolts for the 7.5s and pointed out they were readily available.  So I'm not sure why you need the ones for 8.4s?


Edited by GraemeC, 19 May 2020 - 10:04 AM.





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