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More clutch questions by Tuna Helper
Started on: 06-06-2014 07:13 PM
Replies: 4 (75 views)
Last post by: fierofool on 06-06-2014 10:49 PM
Tuna Helper
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Report this Post06-06-2014 07:13 PM Click Here to See the Profile for Tuna HelperClick Here to Email Tuna HelperSend a Private Message to Tuna HelperEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm having a clutch custom built for my 3800sc swap. The shop wants to make the friction disc thicker and have me shim the pressure plate out from the flywheel about .025. They are also going to shave my flywheel down to .840. So, the questions are, what exactly is the reason for cutting down the flywheel, and am I wasting time shimming the PP out from the flywheel? (so when it wears and starts to slip, I can pull the shims out and not have to replace my clutch.)

After a little searching, it appears that about a quarter inch needs to be taken off the camaro flywheel, is that accurate? in that case, .025 isn't anything to be concerned about, correct?

[This message has been edited by Tuna Helper (edited 06-06-2014).]

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trotterlg
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Report this Post06-06-2014 07:56 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
Shimming a pressure plate out .025 isn't **** , you must have not understood them right or they are idiots. Larry
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fierofool
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Report this Post06-06-2014 09:42 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
If the throwout bearing is in contact with the fingers of the pressure plate and the slave piston has enough travel range, shimming will have no effect. Hydraulics are self-adjusting. As the disk wears down, the piston just moves little further down the bore of the slave, just enough to keep the TO bearing in contact with the pressure plate fingers. When you depress the clutch, you still get the same amount of travel and movement of the pressure plate fingers and it doesn't increase or decrease the pressure against the disk when the clutch is engaged. Shimming the pressure plate up .025 may cause it to come into contact with the bellhousing of the transmission. There isn't a lot of clearance in there with the stock Fiero setup.

By shimming out the pressure plate, you put more lateral sheer force against the bolts. Not a good idea. Larry makes a pretty good analysis of the people suggesting this procedure.
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Tuna Helper
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Report this Post06-06-2014 10:25 PM Click Here to See the Profile for Tuna HelperClick Here to Email Tuna HelperSend a Private Message to Tuna HelperEdit/Delete MessageReply w/QuoteDirect Link to This Post
I didn't know what the thickness was to start with, thats why I was concerned.

They aren't idiots, they build and ship custom clutches all over the country.

I did mention the Spec clutch, he asked what friction material it used and I didn't know. The website doesn't say either. Does anyone know? Fort Wayne Clutch is building a 5 puck clutch with kevlar on one side. I didn't catch what he said would be on the other.
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fierofool
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Report this Post06-06-2014 10:49 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
The reason for cutting down the flywheel is because it's too thick to allow the pressure plate to clear the bellhousing. The throwout bearing forks can only move back so far, too.

I'm not sure what the flywheel thickness should be, but i was thinking it was .820. I'm probably wrong on that, though.
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