Author Topic: Front Disc Brake Conversion  (Read 15028 times)

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Rusty's Uncle

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Re: Front Disc Brake Conversion
« Reply #75 on: May 11, 2017, 08:42:42 PM »
Seems like I have to revive this again to save me some one finger typing  :)

Revived for Nathen  :)

:D OK every time I mention the Disc Brake Conversion for the 126 I get a load of messages which generally ask two main questions ,
What parts do I need ?
& How do you do the conversion ?
It is great to see the enthusiasm and interest but with my "one finger typing" I just do not have the time to type detailed answers to every message.
So I am going to try and cover it here.
I am talking here about the conversion that will suit any 126 or 500 that has 13" wheels and 126 stub axles.

PARTS REQUIRED

Disc Brake Callipers complete with Carriers , Pads , Fixtures & Fittings from or suitable for the Cinquecento , Seicento or early Punto range.
240mms Fiat discs to suit the above.
2 M10 x 1mms Banjo bolts to suit the calliper thread at the flexi hose inlet.
Disc brake adaptor plates.
6 x M8 plate to stub axle mounting nuts & bolts
8 x M10 spacing washers.
Brake Fluid.
TIME - For a reasonably competent DIY mechanic if the parts are all prepared and you know what you are doing then you could probably do this in about 2 hours or half a day with tea breaks.

 PROCEDURE

 Jack up car at front end , remove front wheels , remove brake drum , remove hub , disconnect flexi brake hose by removing banjo bolt from back of brake cylinder then undo the three nuts that secure the brake backing plate to the stub axle & remove brake assembly.
Fit disc brake adaptor plates , refit hub , fit 240mms disc using original bolts , bolt carrier (with or without complete calliper assembly) fitting the spacer washers between carrier & adaptor plates , assemble calliper if not already complete , connect flexi hose using M10 x 1mms banjo bolts & copper washers , bleed brakes , refit wheels & have a test drive .
 **-

Hi , i've been searching through the threads on disc conversions but can't find any set ups for 12" wheels. can your method be adapted to suit them.Cheers Dennis  ( my drum brakes don't give you any confidence )

mintex

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Re: Front Disc Brake Conversion
« Reply #76 on: July 17, 2017, 09:38:26 PM »
ok, its taken me a bit to get my finger out but after a run out with a group of classics at the weekend and having brake problems its time to do the conversion.

I have the plates (cheers Rusty's Uncle :good: ) but are these the brake calipers i need (see attachment) that ive found for sale?

Cheers
Dave

Gadge

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Re: Front Disc Brake Conversion
« Reply #77 on: July 17, 2017, 10:06:59 PM »
There not the ones I used - that's not to say they won't fit - but the common caliper used from a seicento/punto which I think is what rustys' plates are for
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mintex

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Re: Front Disc Brake Conversion
« Reply #78 on: July 17, 2017, 10:16:00 PM »
ah ok cheers, the add says they are from a mk1 punto but that's if the add is correct lol. i did find some but that said they were from a 1.2 16v, not sure if they are different?
Dave

mintex

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Dave

Rusty's Uncle

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Re: Front Disc Brake Conversion
« Reply #80 on: July 18, 2017, 06:27:58 AM »
ive just found these, do they look like the right ones mate? http://www.ebay.co.uk/itm/fiat-punto-1-2-8v-driver-osf-brake-caliper-795211-/253024266424?epid=1409708508&hash=item3ae96be8b8:g:Kf0AAOSwXYtY1A1U
Yes you have got the right ones there along with the all important carrier and M10 mounting bolts  :)

Gadge

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Re: Front Disc Brake Conversion
« Reply #81 on: July 18, 2017, 06:28:46 AM »
That's it Dave, their the ones just make sure they come with the carriers :thumbup
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mintex

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Re: Front Disc Brake Conversion
« Reply #82 on: July 18, 2017, 11:32:23 AM »
Bugger, someone must have been watching this thread as its gone now, i will have to search for more when i get home after work today  :(
Dave

mintex

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Re: Front Disc Brake Conversion
« Reply #83 on: July 18, 2017, 05:46:54 PM »
Sorted, i've just found some more that look a cleaner set, plus they were £5 cheaper  :yahoo:
Dave

candanoglu

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Re: Front Disc Brake Conversion
« Reply #84 on: October 22, 2017, 06:25:33 PM »
Hi friends
I cahnge my brake system with cinqucento for rint,alfaromeo 145 for rear.
So I think so brake pressure is not enough.when. I press the first time to brake is not stop well.but second time more stronger.
I checked my brake system and is not have any defect and air in brake fuild.
Must I change my brake master cylinder?
If I change which one I use?
Thanks..

Gadge

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Re: Front Disc Brake Conversion
« Reply #85 on: October 22, 2017, 06:41:40 PM »
You need a much bigger master cylinder to compensate for the extra space in the caliper cambers. I have front calipers on mine (but not on rear) and I have a very spongy pedal so I fitted an Uno one which is physically the same outside as the 126 version but has a 1mm bigger bore which helps a lot but as you have rear calipers too then you may need an even bigger one so perhaps one from a punto or bravo?
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Rusty's Uncle

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Re: Front Disc Brake Conversion
« Reply #86 on: October 22, 2017, 07:43:20 PM »
I had a discussion about the relative merits of brake cylinders/calipers a few years back with a guy who spent his life working on cars and much of it teaching motor vehicle technology. He pointed out that the piston in a disc brake caliper although a larger diameter than a brake cylinder will only move a couple of thousands of an inch to actuate the brake and may well require less brake fluid displacement than standard drums which pull back the brake cylinder Pistons by springs as opposed to a disc calliper where the piston virtually just rocks against the seal. If you have a spongey pedal or have to pump the brakes then either the master cylinder is faulty or there is still air in the system. There is no reason why you should not get a firm pedal with the standard master cylinder. In fact if you increase the bore on the master cylinder basic hydraulics will tell you that you can increase the flow of brake fluid that should not be necessary  but decrease the braking pressure.

drcdb15

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Re: Front Disc Brake Conversion
« Reply #87 on: October 23, 2017, 12:24:07 PM »
Indeed, it would seem that in going from all-drums to all-discs, you should actually need, if anything, a SMALLER master cylinder rather than a larger one:

http://www.aa1car.com/library/brake_calipers.htm

The apparent improvement observed when changing to a larger master cylinder may be just coincidental, in that by disturbing the whole system and re-filling/re-bleeding, the problem with the original set-up (most likely air still trapped somewhere) has been cured.

Normally you wouldn't disturb the original master cylinder unless you planned to change it. But did anyone ever actually remove it fully, as if to replace, but then re-fit the SAME master cylinder? According to this theory, that should give the same improved performance as is attributed to the replacement larger cylinder.

Gadge

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Re: Front Disc Brake Conversion
« Reply #88 on: October 23, 2017, 02:55:15 PM »
I just figured that that the increased volume in the calipers would require compensating for with a larger volume at the other end but it could be just coincidence like you say. Works beautifully now though.
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