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paul 123

Member Since: 10 Jul 2022
Location: norwich
Posts: 86

1995 Defender 90 300 Tdi HT Auto Rutland Red

brake caliper bolts

i have broken a caliper to axle bolt. its a 300tdi with the metric 12 point head bolts so m12 fine thread. i am confused as to which tap i need to clean all the bolt holes out with. ant ideas as there are various ones m12x1.5 m12x1.00 .

29th Jan 2023 12:34pm

Dinnu

Member Since: 24 Dec 2019
Location: Lija
Posts: 3469

2012 Defender 90 Puma 2.2 CSW Santorini Black

To my knowledge they are 1.25mm pitch.

If you managed to extract a bolt without breaking, you can count 12 thread pitches , so if the distance between the 1st and the 13th thread is 15mm, then it is a M12x1.25. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black

29th Jan 2023 1:09pm

Screbble

Member Since: 26 Apr 2015
Location: Lancashire
Posts: 2109

2004 Defender 90 Td5 XS CSW Zambezi Silver

Re: brake caliper bolts

paul 123 wrote:
i have broken a caliper to axle bolt. its a 300tdi with the metric 12 point head bolts so m12 fine thread. i am confused as to which tap i need to clean all the bolt holes out with. ant ideas as there are various ones m12x1.5 m12x1.00 .

Click image to enlarge

Those 12 point head bolts are notoriously problematic.

I’ve have to grind flats on them it the past to get s decent spanner/wrench on them.

If it is snapped, but you have the caliper removed, then you can probably do the same.

When you do remove it, it would be worth cleaning out the threads with a modified bolt or thread chaser as opposed to a tap.

Hope you sort it 👍

29th Jan 2023 1:28pm

paul 123

Member Since: 10 Jul 2022
Location: norwich
Posts: 86

thanks

29th Jan 2023 2:58pm

Mossberg

Member Since: 29 Feb 2020
Location: Lancs
Posts: 553

1993 Defender 90 300 Tdi HT Aintree Green

This was my experience which may be worth a read. The caliper bolts have two different threads, the finer thread is which I believe was used from the 300tdi/24 spline differential. The coarse thread was the 200tdi/10 spline differential.

I bought myself a set of thread chasers and I am happy I did. They just clear out the threads rather than recutting them. I have used them on many things and the set came with m6, 8,10 & 12 in fine and coarse.

https://forums.lr4x4.com/topic/111496-remo...zed-bolts/

29th Jan 2023 7:56pm

paul 123

Member Since: 10 Jul 2022
Location: norwich
Posts: 86

had a bit of luck with the broken bolt. i drilled through the centre of the bolt from the disc side disc and hub removed. the bolt then came out with an easy out i then cleaned the thread with a bolt and plenty of oil. so all fixed.

30th Jan 2023 2:08pm

Screbble

Member Since: 26 Apr 2015
Location: Lancashire
Posts: 2109

Great result

Glad you got it sorted.

I’ve never had much luck with easy outs on caliper bolts and my Irwin stud extractors didn’t succeed either.

Now you can get on with the job in hand 👍

30th Jan 2023 9:23pm

Mossberg

Member Since: 29 Feb 2020
Location: Lancs
Posts: 553

Well done on getting them out. The learning never stops!

30th Jan 2023 10:21pm

paul 123

Member Since: 10 Jul 2022
Location: norwich
Posts: 86

now the rest of the rebuild can go on

31st Jan 2023 8:54am

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