Switch brake disc from 273mm to 278mm

Hello everyone,

New problem on my early R107 (VIN 107044-12-002393) : the front right brake caliper is seized. The wheel generates enormous vibrations after a few kilometers and it is impossible to turn it by hand.

My car is fitted with the first version of ATE caliper (TEVES) (A 001 421 29 98) and 273 mm discs (A 116 420 01 05).
I noticed that parts for this first version were starting to be rare. For example, I only found 273mm discs at Zimmerman. On auto parts sites, other brands supply 278 mm under the reference A 116 420 01 05 instead of A 116 420 02 05.

I ask myself the following question: instead of repackaging my front calipers (the seal kit is 30 €), wouldn't it be worth to switch to 278mm? I found a pair of reconditioned ATE calipers for € 400 (A 107 420 00 83). There are even brand new NK products at € 260 per pair. I don't know the cost of reconditioning a brake caliper but I think it takes a few hours of work.

Is it technically possible to switch from 273mm to 278mm discs? Are there only the calipers, discs and pads to change?

Thank you !
Jean Charles

Hi Jean Charles

why to switch? Calipers & suitable 273mm discs are available from SL specialists - in case existing calipers cannot be cleaned & re-sealed. No idea if you need to change shield & hoses as well.

best wishes

Yes, we still find 273mm discs, but they are increasingly rare and expensive:

• parts.theslshop.com/mercedes-benz-sl-r107-front-brake-discs/
• £ 270 at SLShop!
• 300 € the pair at Mercedes!
• No longer available from SLS-HH or oldtimer-ersatzteile24.

I only found this ad of reasonably priced Zimmermann records at € 80 per pair:
www.ebay.fr/itm/363445368503

In 278mm, there is a lot to choose from, including the original ATE discs at € 60 a pair.

273mm discs A1164200105 only fitted European and American 350SLs until 1972 according to the EPC and serial numbers. Mercedes therefore moved quickly to 278 mm. Why ?
Is it for a question of efficiency, rapid wear of the pads / discs or simply a factorization with other models ? The drive A1164200105 according to the EPC only equipped the first 350SL. Its replacement A1164200205 fitted all 107 and W116 until 1980 and the A1164200005 all 107 and W126 until 1985 and the later W116. Not surprisingly, we hardly find A1164200105 anymore, the market being too small.

I found an advertisement for new NK calipers at € 220 per pair for 273mm discs without deposit. Afterwards, maybe the original ATEs are better. Another ad with reconditioned ATEs is € 400 per pair with deposit. There are also reconditioned Budweg at € 220 per pair with deposit.

Equivalent parts for 278mm discs are priced the same.

I am studying all the solutions. If my mechanic tells me that the discs/pads also need to be changed, then going to 278mm might be an option.

Hello,
We have successfully upgraded from 273mm to 278mm discs on my early 350 SL. To do this, you have to replace:

• the calipers A 001 421 29 98 and A 001 421 30 98 -> A 107 420 00 83 and A 107 420 01 83
• the discs A 116 420 01 05 -> A 126 420 00 05
• the pads A 001 420 77 2 -> A 001 420 99 20
• the protective plates ????? -> A 107 420 09 44 and A 107 420 10 44

I chose ATE discs / pads and Budweg Caliper calipers. They are half the price of refurbished ATE and the quality seems to be equivalent.

The replacement of the protective plates was a surprise because these specific plates for the 273mm discs are not mentioned in any documentation. Only parts A 107 420 09 44 and A 107 420 10 44 are.

Regards.

Hi Jean-Charles,

what makes you sure that Budweg and ATE are of equivalent quality?

Hello !

I said "seems to be of equivalent quality" because:

• Visually these calipers seem to be of good quality
• The opinions I found on the internet about this Danish brand are all positive.
• They are guaranteed for 2 years (ATE is 1 year)
• This danish company has only been manufacturing or reconditioning calipers for over 40 years and claims to make OEM or even higher quality calipers.

And as in addition they are 2 times cheaper than reconditioned ATE ...

FYI, I also just changed the rear calipers with reconditioned ATEs. We'll see if they last longer than the Budwegs!

Regards,
Jean-Charles