Going hybrid

[JB21]

Quick check and seems Early Prius use same front pads as Mk3 MR2 anyhows

These calipers are from a MK2 Prius 2004-2009, still the same?

[Petrus]

Will know soon enough.

[JB21]

Will know soon enough.

Me too, just purchased a refurbished set myself. £96 delivered. I needed to refub my current MR2 front calipers so this saves me the hassle as well as the bonus of weight saving and a bit more front bias.

[Petrus]

Me too, just purchased a refurbished set myself. £96 delivered. I needed to refub my current MR2 front calipers so this saves me the hassle as well as the bonus of weight saving and a bit more front bias.

Win³

Have the RAL3000 rattle can waiting.

Véry much chuffed there is no mod to the brake lines/fittings needed.

[thetyrant]

These calipers are from a MK2 Prius 2004-2009, still the same?

Yes all same from what i can see until mk3 w3 1.8 Prius

Be interesting to see how the larger piston affect pedal feel and bias, hopefully not too bad

[JB21]

Yes all same from what i can see until mk3 w3 1.8 Prius

Be interesting to see how the larger piston affect pedal feel and bias, hopefully not too bad

Probably a bit more pedal travel, but shouldn't be dramatic.

[Petrus]

Probably a bit more pedal travel, but shouldn't be dramatic.

Would surprise me if noticeable.

But then we will find out.

I find all the ´footnotes´ about possible effects a bit relativated by the total absence of ány observations about the effects on brake ballance of changes in front tire size. 

[thetyrant]

Piston size and pedal travel are funny things, there are lots of calcs you can do and lots of theory etc but often the only way to know for sure is try it on a car when its pretty close like this, sometimes its surprising how much difference a small change makes and other times you can go with lot more piston area and it feels the same, lot to be said for the design of the calipers etc as well but i think it will be ok in this case but we will see!

[Dev]

I have to agree. Just because it fits or is larger doesn't mean it will jive well with the system as a whole.
You could end up getting worse brake feel and modulation. What it can do is feel like a two stage pedal that has play for the take up and then it gives you abrupt braking. This is why the master piston diameter and stroke should be matched to the caliper piston size.

[Petrus]

I think it a great idea which everybody can but nobody needs to try.

[JB21]

My set will be delivered tomorrow so I'll get these fitted over the weekend and I'll report back. I've got a new set of Dixcel race pads to throw in, but I'm going to use the current PBS pads first to get a fair comparison MR2 caliper vs Prius caliper. I'll go out on the MR2 calipers and PBS pads first for a conditions test doing lots of braking from various speeds, then change straight over to the Prius calipers and PBS pads and retrace my steps for a true comparison.

[Petrus]

My set will be delivered tomorrow

They´ll make you smile. I did 

[JB21]

Calipers arrived but there's a problem. One has been rebuilt with a Phenolic piston, the other steel.

Not sure which to replace?

The steel one looks like it could be to big to press on the whole of the brake pad.

On the other hand will the plastic piston be up to the rigour of heavy track work.

Edit: looks like the phenolic pistons are discontinued anyway.

[Petrus]

The discontinuation answers why the the other is steel.
Does not answer your question about whether it is up to track use. Basically underlines that question with ´why discontiuned´ . Can be simply cost of manufacture but for the moment it´s a question.

Is it phenolitic ´plastic´ though. In the specs they are mentioned as ceramic.

As to the shape of the steel one, are the steel backings of the pads not stiff enough?


Back to the weight: Like it?

[JB21]

The discontinuation answers why the the other is steel.
Does not answer your question about whether it is up to track use. Basically underlines that question.

As to the shape of the steel one, are the steel backings of the pads not stiff enough?


Back to the weight: Like it?

Crazy light yeah.

I'll go with what I know in steel. I'll dry test fit first with the MR2 brackets to make sure there's no overhang of the steel piston to the pads, hopefully wont be an issue but the difference between to 2 piston contact patch widths is 7mm. Plastic contact patch is 47mm, steel 54mm. Even if there is a slight overhang I dont think it'll make much of a difference.

From memory of the inner pad imprint on the MR2 51mm piston there is plenty of room for the extra 3mm diameter of the 54mm Prius piston.

[Petrus]

Crazy light yeah.

 

[quore]

Even if there is a slight overhang I dont think it'll make much of a difference.

From memory of the inner pad imprint on the MR2 51mm piston there is plenty of room for the extra 3mm diameter of the 54mm Prius piston.
[/quote]

There is also an up side as it also means a wíder contact area on the pad i.e. abetter spread on the total surface.


For road use, even the most spirited, I only see wins.

Looking forward to your vision on the proof of the puddin´.

[JB21]

Steel pistons are 200g heavier then the OE Phenolic pistons.

1.3kg v 1.5kg

[JB21]

For road use, even the most spirited, I only see wins.

Presumably yours have come with Phenolic pistons? Won't be an issue on the road if so.

[Petrus]

Presumably yours have come with Phenolic pistons? Won't be an issue on the road if so.

Or ceramic?  Not steel.

Indeed, even here in the hót south it will be ok regardless. Not doing heroe stuff steeply downhill anyway. My common sense prefers to have gravity on my side 

[Petrus]

Steel pistons are 200g heavier then the OE Phenolic pistons.

1.3kg v 1.5kg

Thanks for that bonus info!

[Nvy]

Left

https://m.autodoc.co.uk/kamoka/19171256

Right

https://m.autodoc.co.uk/kamoka/19171257

Discs look the same too

https://m.autodoc.co.uk/brembo/7013615

Are the kamoka OEM? I am about to order a set from autodoc

[JB21]

Are the kamoka OEM? I am about to order a set from autodoc

Not sure mate, one of them isn't in stock either.

[Petrus]

Are the kamoka OEM? I am about to order a set from autodoc

As far as I could find Kamoka is one of three OEM suppliers. Could be more even. But then they made a whooooole lot more (1,192,000-second-generation Priusii sold worldwide) than MR2s. Which is another reason to have sóme confidence in Prius calipers.

[JB21]

Confirmation Prius II pads are the same fitment as MR2 MK3.

[Petrus]

Confirmation Prius II pads are the same fitment as MR2 MK3.

Tatáááá  and yet anóther thank you for the confirmation.