Disc sizes

[balleballe]

I'm new to the world of MB having come from 3 previous Honda's.

I have a 2014 e350 bluetec (amg sport) and I'm trying to source some front discs. I have either the option of 322 or 344 diameter. I have the brembo style 4 pot calipers if that helps.

Reg is: GF14 GKN

One merc dealer I've contacted via ebay reckons I need 322 but another seller (mtec) says I need the 'floating discs' @ 344.

Which one is it?

 

[190]

I had a similar problem with inconsistent information on diameter when I changed my discs recently. The only guaranteed solution is to trust yourself rather than others and measure them. While it's not that easy to measure them accurately while they are in place, a difference of 22mm should be obvious enough.

 

[KennyN]

As above , measure the ones on your vehicle to be 100% sure.

Two person job if doing it on the car , a straight edge held on the disc and another 180 degrees opposite then measure between them for the required size.

One person job if you have two 6" steel rulers and two magnets , then measure as above.

K

 

[ray_hennig]

As above , measure the ones on your vehicle to be 100% sure.

Just a thought but couldn't you wrap a flexible tape measure (from a sewing kit?) around the circumference and divide by pi?

RayH

 

[balleballe]

Thanks for the replies. Looks like I'll just measure them.

 

[balleballe]

Just a thought but couldn't you wrap a flexible tape measure (from a sewing kit?) around the circumference and divide by pi?

RayH

From memory: radius = circ divided by 2pi

So diameter should indeed be circumference divided by pi

I'll see which method is easier

 

[Tonye]

Did someone mention pie's, im always up for a good pie

 

[Petrol Pete]

Floating discs on an E350 ? highly unlikely , but It does seem that MB fiddled around with disc sizes (by a few MM) on some models for reasons best known to themselves.

I agree with others on here . Measuring them yourself is the best way to get it right .

MB main dealers can also get it wrong (re: the rear calipers on my AMG C55 don't exist according to Mercedes Benz...I won't bore you with the details.) When you do determine the size be sure to give MB a call for prices of OEM discs and pads as they can be quite competitive on the price of brake parts.

 

[balleballe]

Finally got around to measuring them. They are 344mm. Apparantly both 322mm and/or 344mm were fitted to the 2014 e350's

 

[Benz17]

Floating discs on an E350 ? highly unlikely , but It does seem that MB fiddled around with disc sizes (by a few MM) on some models for reasons best known to themselves.

I agree with others on here . Measuring them yourself is the best way to get it right .

MB main dealers can also get it wrong (re: the rear calipers on my AMG C55 don't exist according to Mercedes Benz...I won't bore you with the details.) When you do determine the size be sure to give MB a call for prices of OEM discs and pads as they can be quite competitive on the price of brake parts.

Terry at Wayne Gates also told me that my 2017 E350d has floating disk.

 

[Petrol Pete]

Terry at Wayne Gates also told me that my 2017 E350d has floating disk.

It might have , maybe modified ? . A quick look at them through the spokes of the front wheel will prove me wrong. In 2017 (and indeed 2022) floating front discs are usually the preserve of C/E/GT class AMG's.