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Rehab a 225 mm "all aluminum S pressure late???

I posted this question in the tracking forum, but thought some of you guys might have had some experience with refreshing an aluminum S pressure plate.
Is this possible??
Is this economically viable?? The $8-900 price tag for a new one is just a bit eye watering.
Anything to recommend or look out for in a used plate??

ever hopefull,
chris

ps, dad's 74 2.7 coupe, soon to have new everything in front of the driver, then trans, then hot EFI engine. Looking for low inertia. Just received a beautiful 6.25 lb wheel from Chris_7
Old 10-11-2017, 05:02 PM
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I think the 225mm all alum. S pressure plate is NLA. The ones you can get now are a couple lbs heavier because the "foot" (I think that's what they call it) is cast iron instead of the coated aluminum one that the early S had. If you have one that is worn, it may be possible to rehab it if the wear isn't too bad. One option is to have the foot / friction plate surfaced and take off an equal amount from the aluminum housing at the perimeter. One thing to note is that the iron friction surface on the foot is quite thin, so you'd have to be careful not to take too much off or you'll be into the aluminum that the early S clutches have. Another option (I haven't tried this, but I've heard it's possible) would be to apply a flame spray coating to the foot / friction surface after having it surfaced.

Scott
Old 10-11-2017, 06:38 PM
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Chris,

If you can dismantle the straps and remove the plate it may be possible to plasma spray a Tungsten Carbide Coating onto the surface nut then it is likley that you would need to grind the surface or the finish would be too rough.

You would have to re-rivet the straps.

We have been looking at this method but the basic coating an grinding process is quite costly.

I thought that the S clucth with the Alumiunium preesure plate was 215mm diameter and the early versions had a copper finish.

t may be easier to make a new pressure plate and try to adapt the unit to operate with Lugs although this may make it more difficult to 'slip' thhan the 'strap' design.
Old 10-11-2017, 08:13 PM
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Contact Kennedy Engineered Products. Maybe they can rebuild?
Old 10-11-2017, 08:35 PM
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I have over the years resurfesed many the Alum. "Sport" 225mm pressure plates with the cast iron foot. Not all machine shops can do but not hard to find one. Yes must cut same amount off alum. housing as required to clean up foot. For a little more hold force can take an extra .010" off the alum. housing.
Old 10-11-2017, 11:18 PM
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From memory when I had my 225mm early S one done, I think I had the machine shop take off like .020-030", and it when I got it back I could see it had removed the iron surface layer and was into the aluminum portion of the foot. So there's not much there to work with. The spray idea could work though. You may be able to just take off a small amount like 010" to true it up and have the plasma spray done to get you back the full thickness, so no need to machine the outer aluminum housing.

Good tip on calling Kennedy - clutches is what they do. Maybe they can help with the plasma spray too. In any case they can probably do the rest and give you good advice.

Last edited by stownsen914; 10-12-2017 at 03:42 AM..
Old 10-12-2017, 03:39 AM
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There was a version of the 225mm clutch where the clamping disc is Aluminium and not cast iron and I thought that the initial question concerned this type of clutch.

They were certainly used in this format on the RSR and I do believe Kennedy make them as new parts.

In the UK we sell a new Sachs Clutch with the Aluminium Cover and cast iron foot for about $450 complete with driven plate and bearing.
Old 10-12-2017, 06:03 AM
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Will give Kennedy a call

I'll give Kennedy a call.
They make an "all aluminum" 225mm PP for $800 that weighs in at 7 pounds.
Was it the 2.2S that had the light pp??
IIRC, the sport clutch has an alum housing, costs about $400 and weighs 13 lb, (iron plate).
Just for grins, I'll give Centerforce a call to see what they have and can do.
Shortly after I got the 308, one of the pucks on their dual friction disc came off and wedged the clutch. They rebuilt the disc with Kevlar and massaged the pp for a little more clamping pressure. They did all of this at no cost, except shipping, even though I had not bought it from them.
Thanks,
Chris

Last edited by chrismorse; 10-12-2017 at 07:11 AM..
Old 10-12-2017, 07:08 AM
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It's possible, but costly.
Old 10-12-2017, 08:04 AM
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To answer the OP's question, it was the 70-71 2.2S that had the 225mm all aluminum pressure plate. I recall it weighing something like 6 lbs, while the aluminum F&S clutch with the cast iron foot (what you can get today) is a couple lbs more. I have one of each and compared them once, and noticed that the 2.2S version also seems to have a thinner spring, so presumably has a lower clamping pressure.

The pressure plate pictured immediately above my post looks like a 215mm clutch.

Scott
Old 10-12-2017, 10:47 AM
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