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Discussion Starter #1
is there any noticeable difference between the 280 and 308 brakes ?

i want to fit 15 inch wheels, but i doubt they will clear my 308's. 16x6's clear. i havent test fitted a 15, to see tho, might just squeeze in ?

the 280 and 308, both use the exact same 57mm caliper and pads, so the physical clamping force wont be any stronger on the 308's, its only the larger disc size, between them.

anyone used both, to compare ?
 

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If you are going to be 'using' the brakes, the 308's will take quite a bit more heat before they fade. With the discs being bigger, you also have a bit more stopping power due to the calipers being spaced further out from the centre of the wheel.

If the car is light enough, and you wont be leaning on the brakes, you make get away with the 280's. I guess it really depends on what you will be doing with the car and how much power it has?
 

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Discussion Starter #3
If you are going to be 'using' the brakes, the 308's will take quite a bit more heat before they fade. With the discs being bigger, you also have a bit more stopping power due to the calipers being spaced further out from the centre of the wheel.

If the car is light enough, and you wont be leaning on the brakes, you make get away with the 280's. I guess it really depends on what you will be doing with the car and how much power it has?
i suppose the extra meat on the beefier disc, favours the temperature threshold, and they have that 14mm further fulcrum point, to help the force. ( newtons law, and all that stuff )

im not racing the car, but i do like my brakes to work, import for safety, i think, as well as fun.

whats your thoughts about 4 pots on the smaller 280 disc ?
i could probably do a cheap conversion, with some d.i.y brackets.

just trying to make the car handle better really - theres big 17's on the car at the moment, they look stupidly big, and they weigh a whopping 20 kilo's each, which is proper heavyweight really. i could probably shave a whole 5 kilo's of unsprung weight off each corner, with 15's
 

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How about trying some lighter 17's and dropping a profile on the tyres? Team dynamics pro race 1.2's are a fair bit lighter. The car was originally set up for 17's, so you should be able to get the handling to work.

The best way by far to help turn in on the G is a rear anti-roll bar, if you don't have one already fitted, I would put this near the top of your list.
 

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Discussion Starter #5
How about trying some lighter 17's and dropping a profile on the tyres? Team dynamics pro race 1.2's are a fair bit lighter. The car was originally set up for 17's, so you should be able to get the handling to work.

The best way by far to help turn in on the G is a rear anti-roll bar, if you don't have one already fitted, I would put this near the top of your list.
there way out my budget unfortunately, probably looking at about 600 quid with tyres, from a quick look on ebay.
i'd prefer to keep vauxhall wheels on the car really, for the standard look.

im kinda set on 15's tho, as the last 2 mk.4's i had, i messed around with various sets of wheels and tyres, and both cars drove way better when i downsized to 15's. even with less rubber on the ground (195's), the handling was better.
they both had the 280 brakes on tho, so fitment, wasnt an issue.

i havent actually tried a 15" rim on the car yet. they might just squeeze over the 308's ?.
a 6J rim bolts up to the hub fine, with clearance, so that side of it, will be ok, but im not sure about the diameter clearance, where the caliper pokes out, thats the tight part.
from what i can see with a 16" wheel fitted, the bleed nipple is actually the furthest out point. it will foul on that, before it hits the caliper.

i'm gonna get my hands on a 15x6, and try it, see how tight it is.
i suspect, at the very least, the bleed nipple will need cutting down. (wont effects is use. just have to bleed onto the floor, instead of into a bleed pipe.
a 15 might not fit, AT ALL, but i want to have a look, and see whats what. if i can get away with keeping the 308's. that would be nice.

ive heard good things about those rear anti roll bars. ive not tried one myself yet.
i managed to get the car to handle pretty good without one tho, so might be able to make it even better with one installed. ill try one, later down the road, when ive got the cash for it (y)
 

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I believe 16's are the min you can get away with for the 308's, you will notice how full a 15" OEM wheel is with the 280 brake set up on, but always worth a try. I didn't think there were many 15" wheel options made in 5 stud fitment?

The rear anti-roll bars do come up used on ebay every so often, so always worth a look.
 
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