Hi Guys.Im going to change front pads.I expect to have to push pistons a long way back into the Caliper to make room.What size G clamp will I need to push the piston back in.Small as 3” or big as 12”?Thanks

 

Any one please?

If you're about to buy a g-clamp to do this job, don't bother. Get a proper toolset with all the different pieces, such as this this tool which will work for just about every caliper out there. If you ever do a rear caliper you'll probably find the piston is on threads so a g-clamp wont work. These are a lot less fiddly than a g-clamp and dont have to use an old brake pad to use it lol.

I agree with Luke. 

I used to push the pistons back by hand on my Sierra but when I got my the ST24 in 2003 I needed a proper wind back tool to do the rear calipers so bought a kit similar to the link above.

23 hours ago, catfish79 said:

Hi Guys.Im going to change front pads.I expect to have to push pistons a long way back into the Caliper to make room.What size G clamp will I need to push the piston back in.Small as 3” or big as 12”?Thanks

 

Trying to push MK1 front pistons back does't always work by hand.You could loosen the brake nipples just enough to make it easier though.I use a large pair of pliers👍

Yes, I have a wind/pushback tool, works on both kinds of calipers.  

it's just this cheap one:

https://www.ebay.co.uk/itm/BRAKE-CALIPER-PISTON-REWIND-TOOL-RIGHT-HANDED-SET-WIND-BACK-KIT-UNIVERSAL-1557i/322435565020

but it does the job.  Well worth getting

 

I've successfully used a G-clamp for many years on the front calipers. The screw pad goes inside the piston to the bottom. Nowadays I use the method recommended by Haynes to clamp the hose and open the bleed screw whilst pushing back. This does, at least, get rid of any fluid that might have become contaminated with moisture. I've never had any problems with the master cylinder seals flipping in the past, though. I think the secret is not to push back too quickly so as not to build up too much pressure in the lines.

As a matter of curiosity does anyone know why the rear pistons are threaded?

16 minutes ago, mjt said:

As a matter of curiosity does anyone know why the rear pistons are threaded?

The handbrake mechanism auto-adjusts by twisting forward as the pads wear. 

 

For front pads I just wedge a small pry bar between the old disc and pad to lever them open, saves all this faffing with G clamps!  

6 hours ago, Guy Heaton said:

Yes, I have a wind/pushback tool, works on both kinds of calipers.  

it's just this cheap one:

https://www.ebay.co.uk/itm/BRAKE-CALIPER-PISTON-REWIND-TOOL-RIGHT-HANDED-SET-WIND-BACK-KIT-UNIVERSAL-1557i/322435565020

but it does the job.  Well worth getting

They're all well and good till you come across a caliper with a left hand thread lol

i use a valve spring compressor on front calipers, pretty much the same as g clamp. just happened to be what was laying around when I was trying to improvise one day 30 years ago and used it ever since

On 5/14/2020 at 1:08 PM, TomsFocus said:

The handbrake mechanism auto-adjusts by twisting forward as the pads wear. 

 

For front pads I just wedge a small pry bar between the old disc and pad to lever them open, saves all this faffing with G clamps!  

I've been using a large screwdriver to push the front pistons back in for 35 years now...I do have a wind-back tool for the rears though 😉

Cheers Guys.Looks like it will be the proper tool!