Rear brake discs fitment

HHave had these in stock for months now, but the brake pedal has got so poor (huge pedal travel) that I decided to replace them before I crashed.
Pedal has been really bad since the last pad change, I have bled them several times assumed the pads needed to bed into the very poor disc surfaces, but they have just got worse.
This is the old discs

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There are quite a few parts to remove, due to the way the discs are made up , ie a complete hub assembly.
Drop off the control arm

This allows you to turn the whole assembly. I drove a chisel into the lower ballpoint mount, to spread it apart, especially as the hub is going in the bin & the ball joint needs to be undamaged

This is the ballpoint separated, it’s the hardest part of the job

Remove the caliper, and undo the driveshaft nut (30mm) and separate the shaft from the hub

Once the pinch bolt is removed, drop the hub from the damper assembly


Now you can clean everything & build the new assembly back together & you end up with this

Now for the interesting part, after doing 1 side, the Twizy had no brakes, even worse than before :-1:
After much deliberation I discovered that the calipers are different to 99.9% of all cars. I had wound the Pistons back to facilitate the new pads & thicker discs THIS IS INCORRECT.
You must adjust the Pistons so that they only just allow the pads to fit, if you wind them back too far, they can’t compensate on their own & you have no brakes.
After a little fiddling, I discovered you can adjust the piston in situ and get a “just rubbing” fit with the new pads & hay presto, a rock solid pedal & fabulous handbrake :sunglasses:. I have never seen a caliper like this before& would guess that many people will or realise this is how they work, hence my post.
Here is a shot of the piston in the caliper

And a small screwdriver in the slot, to rotate the piston
Hope this info helps a few of you out :+1:

1 Like

Very interesting :+1:

Great photos and writeup :slight_smile:
So the same information regarding adjusting the piston applies when just fitting new Pads?

Andy

Yes, they should be adjusted on fitting, but prob again after a few hundred miles when the pads have bedded into your old uneven discs.

Thanks for the writeup!

@lightly So mine should be a doddle on Saturday. :slight_smile Not doing the nubs just the pads and fitting @ALEXAKOS Stainless cylinders to the front.

I’m getting lazy in my old age. :weary:

Yea will ge straight forward enough :+1:

Lightly
I had a new Rear Brake Caliper fitted last week for its MOT
The handbrake travel is too long IMO it takes too many clicks and still does not work that well.
I was going to take the slack up on the Handbrake cable
Do you think I should try adjusting the pistons on both rears before adjusting the Cable even though the pads are part worn?

Thanks

Andy

Are you sure about that? Have you checked with renault?
All similar working rear calipers on cars have a strong spring installed to compensate on the brake pad wearing, to help unwind the piston outward.
What you NEED to do is grease up the rear of the pad touching piston so it can twist its self outwards. Its true that it takes a few breaking times until they sit onto the right spacing.
As for the indents for winding the piston down, there is a special tool for that. Hitting it with a screwdriver and hammer may create edges on it, that will not help it rotate outwards when the pads wear.

All in all a very nice and clear photographed tutorial :slight_smile:

I am not 100% sure of the facts here & happy to be corrected as I have not contacted Renault. I will try & do this this week .
I know for sure that the piston does not rotate on car calipers, it’s a coarse threaded rod inside the piston, that winds out & adjusts the piston, as the piston could never rotate on the pad, in fact many cars have a locating peg on the pad to locate with the piston.
I was in such a bad state with my Twizy, that I removed the caliper completely & was prepared to completely dismantle the caliper to see what was wrong. I tried to expel the piston using compressed air , similar to how I pop out the front ones. While doing this , I noticed the piston would move @ 4mm & then return back into the caliper, no matter how many times I tried it. This is obviously what was happening when you press the brake pedal, so if the pads are 4.2 mm away from the piston, it will never move enough to give you a brake pedal.
Hence I adjusted the piston manually & have a fab foot & handbrake.
I am happy to accept that my calipers may be knackered & causing this fault, but doing this has cured the issue, and there was no evidence of corrosion or seizing at the rear, because it has a much better dust shield than the front.
Hopefully Renault will have a definitive answer, but as someone has already mentioned, after a new caliper was fitted, their handbrake is poor.
I don’t think my handbrake has ever been as good as it is now.

I hope you find out before Saturday morning then we can test it on mine.

Awesome lightly.

In most cars with this caliper design, it is the application of the handbrake that continually turns the threaded piston and takes up the slack. It really should be automatic on handbrake use, as it is dangerous if not…

Hi guys, great write up on these installations.

Anyone know where to buy a rear calliper apart from Renault ? Their £201 asking price for one calliper is extortionate to say the least and I need one as the handbrake not holding on one of my rear wheels.

Thanks in advance

Paul

Provided it is not seized then have you screwed the piston out?

How do you do that please? I’m not technically minded :wink:

See my other reply but I would suggest you cannot do it, unless shown. I gave an alternative fix for now.

https://www.leboncoin.fr/equipement_auto/913732875.htm?ca=8_s

Complet set here for 200

prices gone up lately…

Just had front pads (supplied by Lightly) fitted to my Twizy by my local independent garage. They charged me £30 which I think is reasonable.
The pads were down to about 1mm. They said the rears are still OK. I have done just under 13000 miles.
My handbrake is getting a bit “long”. I asked them to adjust it but they said they are not sure how it’s done. Has anyone got any tips? Thanks.