Supercharger Owners

[Rob]

I will do but it will be a long time because I am back in the UK tomorrow for a few weeks so I will get a puller while I am there.

I had a scan of the merc forums and someone there has replaced the bearing with some pics and the drive pulley is exactly the same as ours - except instead of the clutch plate being riveted to the plastic cover, the rivets have been removed and the whole lot is bolted together.

so you are relying on 3 tiny screws and a bit of plastic to transfer the load - crap design in my opinion. My plans will be to replace the plastic cover with a thicker aluminium cover but its a fair bit of work to get everything right or you will have balance problems.

[RX-Men-8]

I will do but it will be a long time because I am back in the UK tomorrow for a few weeks so I will get a puller while I am there.

I had a scan of the merc forums and someone there has replaced the bearing with some pics and the drive pulley is exactly the same as ours - except instead of the clutch plate being riveted to the plastic cover, the rivets have been removed and the whole lot is bolted together.

so you are relying on 3 tiny screws and a bit of plastic to transfer the load - crap design in my opinion. My plans will be to replace the plastic cover with a thicker aluminium cover but its a fair bit of work to get everything right or you will have balance problems.

The "Plastic Cover" is a flexible disc, with "Uni-Damp" written on it.

That suggests it's a vibration-damper. It may mean that if you bolt on something more rigid, comfort may suffer.

On mine it's fastened with 3 Torx screws, and they're still tight (30.000km).

[Rob]

I will do but it will be a long time because I am back in the UK tomorrow for a few weeks so I will get a puller while I am there.

I had a scan of the merc forums and someone there has replaced the bearing with some pics and the drive pulley is exactly the same as ours - except instead of the clutch plate being riveted to the plastic cover, the rivets have been removed and the whole lot is bolted together.

so you are relying on 3 tiny screws and a bit of plastic to transfer the load - crap design in my opinion. My plans will be to replace the plastic cover with a thicker aluminium cover but its a fair bit of work to get everything right or you will have balance problems.

The "Plastic Cover" is a flexible disc, with "Uni-Damp" written on it.

That suggests it's a vibration-damper. It may mean that if you bolt on something more rigid, comfort may suffer.

On mine it's fastened with 3 Torx screws, and they're still tight (30.000km).

i have searched for unidamp on the net and nothing comes up - but i have found the company in the US makes the clutch assy for eaton and merc - which is where our SC's come from. Unidamp efers to the clutch plate material as it is made of a low noise( when the electro clutch engages) material thats why it says damp, it has nothing to do with vibration damping.

i have found that the bearing in the pulley IS NO LONGER MADE so if your wears then tough there is nothing you can do about it.

[Rob]

as an update - i sourced a bearing for the drive pulley

The bolts that had sheared are actually 5mm diameter and of very poor quality - I RECOMMEND EVERYONE WITH THE ORIGINAL BOLTS TO REPLACE THEM!

I found out the original bolt holes are not exactly on the same circumference so a vibration issue exists - I have corrected this by machining the holes to 1/4 inch UNF -28 pitch thread. The pulley has been vibration tested at 10,000 RPM with a minimal vibration result :D

The SC is in its component parts, I have replaced the bearings and sprayed the body with etch primer earlier - top coat is tomorrow.

Just waiting on the oil seals to arrive which should be next week.

Photos will follow in the next week.

I will also see if i can mill out a new cover cap for the pulley as the current plastic cap is crap

[Rob]

hmm,

Well if you get inside the mechanism can you let me know mate.

stav

what do u need to know?

[sparkystav]

anything is possible... merc USED to have the magnetic clutch system but they have ditched that becuase there were a lot of problems with the clutches - the newer models have a permanent drive compressor. The signal was sent via the ECU so you would need some way of controlling it.

As I am at the moment unable to remove the pulley from the shaft I can not tell you if the electromagnet is still left inside.

TBH the conversion to a permanant drive compressor from a magnetic clutch design leaves a lot to be desired - the only thing joining the 2 parts of the pulley are the 3 small screws on the fron of the cover plate and the screws are no more than 4mm in diameter.

If I had know this was the arrangement I would have replaced the screws with stainless steel bolts a long long time ago.

About the Electromagnet weather it can be made to work again?

Also have you got a picture of where these bolts are that require changing, and what length are they, and finally are they allen head, or bolt?

Stav

[Gord]

anything is possible... merc USED to have the magnetic clutch system but they have ditched that becuase there were a lot of problems with the clutches - the newer models have a permanent drive compressor. The signal was sent via the ECU so you would need some way of controlling it.

As I am at the moment unable to remove the pulley from the shaft I can not tell you if the electromagnet is still left inside.

TBH the conversion to a permanant drive compressor from a magnetic clutch design leaves a lot to be desired - the only thing joining the 2 parts of the pulley are the 3 small screws on the fron of the cover plate and the screws are no more than 4mm in diameter.

If I had know this was the arrangement I would have replaced the screws with stainless steel bolts a long long time ago.

About the Electromagnet weather it can be made to work again?

Also have you got a picture of where these bolts are that require changing, and what length are they, and finally are they allen head, or bolt?

Stav

Stav, front of your charger mate, star drive :D 3 of them.

[Moffet]

Mine are standard cross head screws, not stars. Is that bad?

[Rob]

mine were phillips also - it doesnt really matter what head sytle they have - all i can say is that mine were made of very cheap and weak material. I suppose if they had been changed for a decent strength - stainless or high tensile bolt then it wouldnt have happened.

The clutch can be activated I suppose but would require a switch on the dash

[Rob]

ta jamie - if it helps someone in the future with the same problem then thats good. For info the bolts were installed with loctite so required heating the area with a hot air gun.

given the quality of the bolts im surprised this has not happened more than twice - but suspet TTE changed the bolts once the problem was known ( TTE do know of this problem BTW)

[Unregistered_User]

Rob,

Do you think that this has been rectified on the newly available and revised models (those that are now being sold with manifold etc.)? Or will this have been applied to previous models?

I'll be replacing most of the engine bay bolts / screws so would like to change these at the same time then. So if you could provide details on what you replaced the OEM TTE items with that would be appreciated.

Many thanks,

Jamie

[Rob]

i have no idea if the newer models have better bolts but I would assume so as people have reported different types/head styles of bolts - The bolts i had were black and cheap. Regardless of the currently fitted bolts, if it was my car, knowing what I know now I would remove the original bolts and replace them with bolts that I know are of high strength. You can get stainless steel hex headed bolts for about £1 each but remember to buy thread lock also!

The bolts I will be using are not generally available ie u cant walk into a normal shop and buy them (ms9557-8 - its a turbine engine bolt) but they are larger and the pulley was placed in a CNC machine to ensure 100% accuracy of the larger holes - you dont have to do it this way but as i have the facilities available........

[Unregistered_User]

I see what you mean, Rob. I was just wondering if you had an idea of dimensions etc of the bolts / screws, so that rather than me removing them to take into a hardware shop, I could name a spec.

Are they easy to remove if I wished to take one into the store?

J

[Rob]

should be quite easy to remove - they will have thread lock so make sure you have a good fitting screwdriver or torx bit - measure them then just order it online - i have ordered some stuff from www.a2stainless.co.uk in the past and had no complaints, remember to put thread lock on them when putting the bolts back

[Unregistered_User]

Threadlock being the blue sealant you generally find on bolts etc?

J

[Rob]

that is a variety of threadlock - have a look for loctite liquid thread lock try loctite 242 which is medium stength so can be removed if required.