308 Brake conversion

[The Coolest]

Hi guys,
I'm considering changing the GTI6 front brakes to a 283mm Bosch setup from a 308. The reason for this is mostly the cost and availability of 22mm thick discs where I live.
I know of many people upgrading their 306s and ZXs to 307 setups, and that they fit no problem, but haven't heard of anyone going the 308 route yet.
I found a set with good discs and pads for a really tempting price, so I'm simply trying to figure out whether this is going to work or not.
Has anyone tried going the 308 route? Is this a direct fit conversion or will it require me to make modifications?
I have seen that the brake pads have a lot more surface area, which is nice, but I'm wondering how much extra weight (if any) will the calipers add? (Discs are 6.6kg vs 5.95kg)

[MY95]

Cant really help you with this, but did many miles in a 308 HDI 112 on a 2010 plate with those 283mm Bosch Brakes, and with the master cylinder too they give sooooo much confidence! Absolutely astounding feel as well as stopping power!

[Redordead89]

Never driven the 308 but got to think any upgrade to your brakes is worth doing if it fits!

[Piggy]

Er... You may struggle to fit the discs!

Have a look at stud patterns

[tigerstyle]

I can see 4 stud and 5 stud options?

[The Coolest]

Thanks for the replies so far, guys.
I've looked into this, 307 brakes fit no problem and they use the same discs on the 308s, just a different caliper and pads.

[Piggy]

306 gti6 brakes with well chosen discs and pads are EPIC and will see you through lots of track action...

Not sure the point of opting for a more expensive setup for no gains?

[The Coolest]

The problem is that the discs for the GTI6 are very expensive here. Almost 3 times the price of OEM 307\308 discs.

[welshpug]

tbh, I doubt you would ever need another set of discs so I would just get standard ones.

or go for a holiday and bring back discs...

[Jonny81191]

tbh, I doubt you would ever need another set of discs so I would just get standard ones.

or go for a holiday and bring back discs...

Er, what? You realise discs wear out, yes?

[welshpug]

totally, but its a 15-20 year old cheap french hatch, unless the o.p does big miles theyll outlast the car.

[Jonny81191]

totally, but its a 15-20 year old cheap french hatch, unless the o.p does big miles theyll outlast the car.

Mm, I'd argue that but I see your point, they'll certainly last a while

[The Coolest]

I appreciate the feedback, but the thread is getting a bit off topic.
In the long run keeping the original setup will cost more. I would hazard a guess that the 308 setup is more modern, most likely a better design and perhaps has better performance. It will not be affected by scarcity and high price of parts, and other age related wear and tear of an aging brake setup, which has long been discontinued and is only used in a handful of cars that are still on the road.

[The Coolest]

I wanted to update this thread, in case anybody was interested in making this change as well. I ended up staying with the GTI6 setup for now.
But what I found out is that this set should fit any 306\106\ZX\Saxo etc. The only thing you have to worry about is for your wheel to have the proper offset for the caliper to fit, otherwise you're going to need to use a spacer.
One person who installed this setup on his Saxo said he had to use a 5mm spacer with standard steel rims. I'm guessing that if you get alloys with the proper offset value you could get away with a straight fit without any other changes.

[adam b]

You can fit pretty large brakes under the right 15" wheels!

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Shame cyclone spoke clearance is so crap

[MY95]

Looking back into this (as looking to upgrade to 283mm and 308 calipers will be a lot newer than 206/306/307 ones) it looks like they fit as they have the same pitch circle (108) and hole arrangement/number of 04/06.

Piggy what are you meaning by different stud pattern?

Would you really feel the difference in acceleration/turn in with 2kg + caliper weight more each front wheel?

Specs:

306 266 =4.7KG, 20.5mm, 27.4 Height
306 283 = 5.95KG, 22mm, 27mm Height
206/307/308 283 = 6.74KG, 26mm, 34mm Height

[BiG K]

Would you really feel the difference in acceleration/turn in with 2kg + caliper weight more each front wheel?

You definitely feel the difference...but I prefer it. It feels more solid.

[MY95]

Would you really feel the difference in acceleration/turn in with 2kg + caliper weight more each front wheel?

You definitely feel the difference...but I prefer it. It feels more solid.

As in more planted and stable?
Noticed any difference in acceleration or not really noticeable? 308 setup would be great as newer caliper than 307, looking at 207/208/406/407 setups too.

[Rippthrough]

Would you really feel the difference in acceleration/turn in with 2kg + caliper weight more each front wheel?

Yes. Makes a noticable impact on acceleration, ride, handling, when I took my lightweight discs off and fitted some standard ones it felt like I was permanantly carrying a passenger...

[MY95]

Ah not ideal then, although thats what you expect I suppose, with more unsprung weight etc.
I see the bosch 266mm are newer, worth the upgrade? only 0.3kg more a disc and will be a lighter caliper.

[BiG K]

Would you really feel the difference in acceleration/turn in with 2kg + caliper weight more each front wheel?

You definitely feel the difference...but I prefer it. It feels more solid.

As in more planted and stable?
Noticed any difference in acceleration or not really noticeable? 308 setup would be great as newer caliper than 307, looking at 207/208/406/407 setups too.

This is just my opinion and even then, it's just what I feel and not what will translate into hard figures. It feels more planted and solid as like Ripp says, it feels like there's another passenger with you...but without the weight penalty of a passenger. Adding any weight to a car is going to slow it down but a few kilos is negligible at worst.

What happens is, there is a larger mass of steel spinning and a large mass of steel wants to spin true. So when you try to turn it off axis, it will resist that movement, resulting in more force needed to turn the steering wheel. I prefer that feel whereas I think Ripp prefers a light  chuckable feel, it all boils down to personal preference.

If you look at the big brake kits of today, you'll notice the calipers are nearly always monoblock design, whereas older multi piston calipers were a two piece design with bolts to hold it together. The older system had far more flex , which reduced efficiency. But the 308 is not a race car and ultimately there will be a tradeoff in price, so the 308 calipers may not be noticeably better.

[Rippthrough]

I prefer to feel the road and tyre rather than the gyroscopic effects from my spinning dinner plates
Put it this way - you could time the difference in acceleration from my lightweight discs to standard ones - without even considering the ride and handling improvements.

Two piece vs single piece isn't really relevant when it's a sliding single piston cast iron caliper....they're certainly no better design than the 307/206's

[welshpug]

a few kilos of rotational unsprung weight is certainly more noticeable than an extra passenger