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How to retro-fit the 312mm front brakes to a Mk7 Golf

golfdave

golfdave

Autocross Champion
Location
Scotland (U.K.)
Car(s)
Mk7 Golf GT Estate
autovelocity said:
SUCCESS!

The 312mm rotors and new caliper carriers fit perfectly.
The difference from 288mm to 312mm is night and day!!!!! I can actually brake progressively and with confidence.

With 288 --> http://imgur.com/a/i1ifT
With 312 --> http://imgur.com/a/eQsoB

Visually it looks nicer as it fills the entire dust shield plate and also more of the inner wheel.
Click to expand...

Great!...when I get time I'll properly add your caliper part numbers...

Very strange that VW use one completely different number for the same part on the same car...

& YES the braking system was designed for 312mm....just they downsized by using a 288mm disc for the lower powered cars...BUT did NOT alter the servo or piston sizes which is why the 288mm setup is grabby & then fades under duress..:cool:
 
A

autovelocity

Passed Driver's Ed
Location
Canada
Car(s)
18 R
golfdave said:
Great!...when I get time I'll properly add your caliper part numbers...

Very strange that VW use one completely different number for the same part on the same car...

& YES the braking system was designed for 312mm....just they downsized by using a 288mm disc for the lower powered cars...BUT did NOT alter the servo or piston sizes which is why the 288mm setup is grabby & then fades under duress..:cool:
Click to expand...

Forgot to mention, caliper housing # 5QM 615 123 also has a 55mm OD piston.
The one thing I noticed was a little more front end side-sway when turning harder due the extra bit of unsprung weight of the new parts. Of course the OEM suspension is terrible to begin with and I'll be putting in H&R coilovers soon to resolve that problem :)
 
Last edited:
golfdave

golfdave

Autocross Champion
Location
Scotland (U.K.)
Car(s)
Mk7 Golf GT Estate
autovelocity said:
Forgot to mention, caliper housing # 5QM 615 123 also has a 55mm OD piston.
The one thing I noticed was a little more front end side-sway when turning harder due the extra bit of unsprung weight of the new parts. Of course the OEM suspension is terrible to begin with and I'll be putting in H&R coilovers soon to resolve that problem :)
Click to expand...

So it has the 55mm piston & NOT the 57mm piston?

I worked out that my caliper, 57mm piston (same cast as GTI 312mm) which was fitted with 288mm discs should be downsized to 55mm piston to work better for the 288mm discs (see my first post in this thread).

So your 55mm piston will have to work harder on the 312mm discs...:(
 
A

autovelocity

Passed Driver's Ed
Location
Canada
Car(s)
18 R
golfdave said:
So it has the 55mm piston & NOT the 57mm piston?

I worked out that my caliper, 57mm piston (same cast as GTI 312mm) which was fitted with 288mm discs should be downsized to 55mm piston to work better for the 288mm discs (see my first post in this thread).

So your 55mm piston will have to work harder on the 312mm discs...:(
Click to expand...

Unless I measured the caliper piston wrong, it is 55mm from what i've seen. However I only measured the OD of the exposed piston, not the piston behind the rubber boot.

I found this article https://www.zeckhausen.com/catalog/index.php?cPath=6446_6472 and from the looks of it, the true piston diameter is determined by measuring the OD of the inner piston and not the exposed portion. (of course this could be different for other manufacturers)

That said, the braking feels excellent so far.
But do you think there would be a safety issue if the caliper has to work harder on the 312 vs the native 288mm rotors?
 
golfdave

golfdave

Autocross Champion
Location
Scotland (U.K.)
Car(s)
Mk7 Golf GT Estate
autovelocity said:
Unless I measured the caliper piston wrong, it is 55mm from what i've seen. However I only measured the OD of the exposed piston, not the piston behind the rubber boot.

I found this article https://www.zeckhausen.com/catalog/index.php?cPath=6446_6472 and from the looks of it, the true piston diameter is determined by measuring the OD of the inner piston and not the exposed portion. (of course this could be different for other manufacturers)

That said, the braking feels excellent so far.
But do you think there would be a safety issue if the caliper has to work harder on the 312 vs the native 288mm rotors?
Click to expand...

having taken apart VAG brakes the piston is the same diameter the full length...

Safety issue...well you will get fade& the pads/caliper will get hotter...to get the full use of the 312mm disc..so better brake fluid, & my air guides?

I don't think in everyday driving you will get problems compared to pushing the standard 288mm setup you had from the factory TBH..:cool:
 
A

autovelocity

Passed Driver's Ed
Location
Canada
Car(s)
18 R
golfdave said:
having taken apart VAG brakes the piston is the same diameter the full length...

Safety issue...well you will get fade& the pads/caliper will get hotter...to get the full use of the 312mm disc..so better brake fluid, & my air guides?

I don't think in everyday driving you will get problems compared to pushing the standard 288mm setup you had from the factory TBH..:cool:
Click to expand...


Good to know.
The factory 288mm warped on me after 6 months of driving (brand new car)
On the highway I would get serious vibration when braking from 120km/hr

So far with this 312mm it's excellent, but I'll keep an eye on it.
 
A

autovelocity

Passed Driver's Ed
Location
Canada
Car(s)
18 R
I did about 30 mins of driving in somewhat congested city driving and measured the rotors at about ~69-80c and calipers at mid to high 50's.
Those temps are about average with other vehicles in city driving.

Ill try some harder braking on winding roads/highway later.
 
Elwood

Elwood

3-7-77
Location
Long Beach, CA
I think you may be onto something based on the size of the dust shield alone. It will clearly accommodate a larger rotor. It looks like the carrier will, too. I just have a basic Golf, btw.

Edit: Unless the caliper moves farther away from the hub, there is no increase in leverage and, therefore, no increase in braking power. You will have better heat dissipation, however.
 
Last edited:
Gawernator

Gawernator

Go Kart Champion
Location
Fremont, CA
autovelocity said:
SUCCESS!

The 312mm rotors and new caliper carriers fit perfectly.
The difference from 288mm to 312mm is night and day!!!!! I can actually brake progressively and with confidence.

With 288 --> http://imgur.com/a/i1ifT
With 312 --> http://imgur.com/a/eQsoB

Visually it looks nicer as it fills the entire dust shield plate and also more of the inner wheel.
Click to expand...

Very nice upgrade. If I come across the GTI carriers I will have to do that... haven't found anyone willing to sell the carriers without the caliper.. might just go that BFI route, not sure. That is a pretty good visual difference too.
 
A

autovelocity

Passed Driver's Ed
Location
Canada
Car(s)
18 R
pokeyjoe said:
I think you may be onto something based on the size of the dust shield alone. It will clearly accommodate a larger rotor. It looks like the carrier will, too. I just have a basic Golf, btw.

Edit: Unless the caliper moves farther away from the hub, there is no increase in leverage and, therefore, no increase in braking power. You will have better heat dissipation, however.
Click to expand...

I just inspected my existing rear caliper/carrier and it would be impossible to fit the 272mm rotors without having a different carrier.
I guess the A at the end of the part #'s really have different physical dimensions for some parts.

I will have to investigate this further.
 
Gawernator

Gawernator

Go Kart Champion
Location
Fremont, CA
BFI's package is a bad deal btw, if you buy the carriers brand new it's about $190, and Pelican Parts has the zimmerman rotors for $100... MUCH less expensive for the same thing.
 
MeltedSolid

MeltedSolid

Autocross Newbie
Location
San Francisco Bay Area
Car(s)
'15 Golf, e36 328i
The best I've seen for the carriers was $130ish each, is that $95 each you found them for?
 
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