The BMW Mini M45 supercharger is based on Eaton’s well proven roots technology. Found in two variants in the R50, R52 & R53 models with early grey epoxy coated rotors and later black abrade-able coating.  The BMW Mini Cooper S has been a great success and has attracted a host of modifications one of which being upgrades to the supercharger.  This M45 is also an aftermarket choice for bolt-on supercharging of some Honda’s and Mazda MX5’s.

Although good, these superchargers can be subject to premature seal or bearing wear, and in some cases failure of the drive coupler.  Rattling at idle is the first indication that something is going wrong, usually that a bearing is starting to wear, or that a drive coupler is fractured and failing.  The important thing is to have them repaired when you hear early signs of something being wrong – if they are left rattling too long, the damage will spread from bearing wear, which is curable, to wear of the rotors and/or main casing, which can become bad enough to scrap the supercharger.

Please note all prices noted below unless otherwise stated include UK vat at 20%.

Not your typical supercharger!

Just as many OE manufactures do, BMW have created a bespoke supercharger unique to the Cooper S.  Using Eaton’s very dependable M45 rotor group they have created a supercharger that utilize the supercharger shaft to drive the water pump on the opposite end via a small power take-off gearbox (PTO gearbox).

Although this is very convenient and necessary to get such a supercharger in the confined space of the BMW Mini, it has also become the backbone of failures on these units. Premature seal failure leads to oil loss in the PTO unit, gears then rapidly wear and fail losing all drive to the water pump leading to a host of overheating issues and supercharger noises.

Repair – this failure has previously been a potential scrapping issue with the worn gears not being available from BMW or Eaton.  Repairs have been undertaken by sourcing good used condition gear sets, but these are hard to find with most people opting for the used market risking purchasing a similarly worn blower.  Final choices have been to choose 1 of 2 aftermarket manufacturers of replacement gears but being forced to use their rebuild services at a hefty price tag to get them but NO LONGER.

We at Powerhouse are happy to announce that we can now replace the worn gears in your Mini, as well as all other bearings and seals, for brand new UPRATED GEARS designed and produced to our specification.  To our knowledge we are the only aftermarket company to have kept true to Eaton’s design features by incorporating their custom gear profile designed to match oil viscosity to the high speed of the gears.  We have also upgraded the gears by opting for a wider gear to reduce the load per gear tooth and reduce the risk of total gear wipe-out as seen on some units.

M45 MINI SNOUT REBUILD

If the issue you’re having are limited to just the snout of the supercharger, like a leaking end seal, we can rebuild the snout only for £125 plus return shipping.

Sending the snout alone will be lighter and cheaper to ship than the full supercharger, but before you take this option remember the main rear bearings are prone to failure, and you may wish to avoid a future repeat of the process to remove and refit the supercharger for the sake of two more bearings first time around by opting for our base supercharger rebuild service!

Eaton BMW Mini M45 Supercharger Rebuild Services 3

BASE M45 MINI SUPERCHARGER REBUILD

Our base rebuild service replaces all the major components typically required on most supercharger plus a few specifics.  This rebuild includes a full inspection, deep clean, snout rebuild, rear case bearings, case-PTO seal, case PTO needle bearing and fresh oil for both Snout & PTO gearbox for only £425.

For a more in-depth rebuild see our ‘Rebuild Plus PTO’ below.

M45 MINI PTO REBUILD SERVICE

Our Mini Cooper S PTO rebuild service replaces all bearings and seals in the PTO and Supercharger case required to maintain your PTO and guard against the biggest known weak point on the Mini M45.  If your PTO has already failed we can also provide new PTO gears, new PTO shafts, and seal repair sleeves to repair excessively worn rotor shafts. Our prices start at £323 for our PTO rebuild service.

If your PTO is in a bad way and also needs new gears, these are available in pairs for an additional £175.  Our uprated PTO gears have been specifically designed to maintain Eaton’s custom gear tooth profile, a detail that others appear to have swapped for easier to produce standard gear profiles, and have a wider gear face to reduce surface load and wear.  UK produced to the finest tolerances, and surface hardened in quality steel, our PTO gear sets are the best you can buy and the ideal replacement for worn OE gears.

Eaton BMW Mini M45 Supercharger Rebuild Services 4

PTO shaft replacements are also available for just £45, if your PTO has run dry or been found with sludgy contaminants seal surfaces can be found excessively worn.  These can be added to a rebuild if a worn shaft is found during inspection.
We can also offer additional services such as our base PTO rebuild that focuses on the PTO shaft, bearings & seal only that drops our service cost just £139.  For more services please contact us for a quote.

M45 MINI REBUILD plus PTO

This is our full package for the Mini M45 Supercharger, combining both our base rebuild service and PTO rebuild service.  This service starts at £520 with additional items such as our PTO gear sets and PTO shafts that can be added if wanted or needed.

M45 MINI ROTOR PACK BEARINGS

The Eaton M45 supercharger rebuild service does not include recoating the rotors or changing the pair of bearings and seals which live between the rotors and timing gears in the middle of the rotor pack.  This is because at manufacture Eaton rolls the casting onto the bearing outer race, permanently sealing them in and meaning the casing has to be fractured to remove those bearings.  That said, these are in an oil bath and rarely fail – if on inspection we discover they have failed, we do not charge for the strip and would inform you we cannot recover the supercharger.  On this supercharger type that is less than a 10% risk. Although some service providers in the US do offer rebuild the rotor pack, Eaton Corporation themselves consider this to be an unreliable and often unsuccessful route to repair – when the rotor pack is worn out or damaged the only dependable solution is a new rotor pack.