I'm in progress to assembly my clutch. I have refurbished my flywheel and should now mount it to the engine. My question is do I need a shim and if how to do it right. The shims is supposed to go on to the crankshaft and backside of the flywheel? Seems hard to align it right when the shims is at place.

Very grateful for answers
Hobby mechanic Kristian
Sweden 🇸🇪

Welcome to the Forum!

What did you have done to your flywheel? A normal re-surfacing requires no shims.

I hade some dents mashined of from the surface. If I remember correctly so did the previous owner t. And I have no idea what thickness the flywheel measured unfurnished.

What motor do you have? Maybe someone on the forum will know the original thickness.

I have a v6 with a 4-spd. I have around 0.590" on my flywheel.

It seems that shims are never needed....according to the archives.

https://www.fiero.nl/forum/A...020825-2-019953.html

[This message has been edited by Gall757 (edited 07-19-2018).]

quote Originally posted by Gall757: It seems that shims are never needed....

Sorry Gall, but I've got to disagree with you on this. Years ago, I had researched flywheel shim use... and decided it was definitely the route to go for my Fieros.

From this thread...Two questions pertaining mostly, but not exclusively to '88 2.8 flywheel

quote Originally posted by Patrick: This is something that has been discussed and debated here for years. Here's the argument - Even when new from the factory, the Fiero clutch system barely gives enough throw to completely disengage the clutch. When metal is removed from the flywheel during resurfacing, the flywheel becomes thinner. The clutch pressure plate mounts to the face of this thinner flywheel, and is now positioned further away from the clutch fork. This then changes the whole geometry of the clutch fork in relation to the throwout bearing, pressure plate, slave, etc. Whatever it changes, it appears the ("self-adjusting") hydraulic clutch can't effectively make up for this difference. The end result is that the clutch now becomes difficult or impossible to disengage properly. Because of this situation, some experienced Fiero owners/mechanics insist on simply replacing the flywheel with a new unit anytime that the clutch is replaced. Other experienced Fiero owners/mechanics use a shim behind a resurfaced flywheel instead of replacing the flywheel. The shim behind the flywheel pushes the face of the thinner resurfaced flywheel back to where it originally sat in relation to the rest of the clutch system components. I know it seems that .025" or so wouldn't make a bit of difference, but there are too many Fiero owners/mechanics who know a heck of l lot more than I do who absolutely swear by this. And for $10, I'll splurge on a shim to prevent potential shifting problems.

[This message has been edited by Patrick (edited 07-19-2018).]

As these cars age and pass through many hands, it would be nice to have a thickness number for the stock flywheel from the factory. At least then the car owner can make a decision about the risk of using a shim or not. It seems that nobody knows what that is, or how far out of spec. you can be and still have the clutch work correctly. I have yet to read a thread where the OP had clutch problems and fixed it by adding a shim to the flywheel or getting a new one.

quote Originally posted by Gall757: I have yet to read a thread where the OP had clutch problems and fixed it by adding a shim to the flywheel or getting a new one.

Not much of a surprise... I mean seriously, who's going to go through all the hassle of dropping a tranny ONLY to install a flywheel shim?

quote Originally posted by Gall757: ...it would be nice to have a thickness number for the stock flywheel from the factory.

In the thread I linked to, I asked if anyone had that information... but no response. So I spent the $5 for a flywheel shim anyway, and never regretted doing so.

quote Originally posted by KriPau: I have a v6 with a 4-spd. I have around 0.590" on my flywheel.

Sorry for the late reply, but this is likely going to be an issue.
A normal flywheel is around 0.83" and when surfaced they normally take 0.010" to 0.030" off. Yours has about 0.24" or 1/4" removed. I would be concerned that this flywheel is too thin and more prone to cracking or worse. I would try and get a new replacement.

quote Originally posted by Patrick: Sorry Gall, but I've got to disagree with you on this. Years ago, I had researched flywheel shim use... and decided it was definitely the route to go for my Fieros.

In theory to restore everything to the stock setup once a flywheel has been surface, you should install a flywheel shim equal to the amount of material removed. This works and there is nothing wrong with doing this.

However, in practice, with the stock fiero manual transmissions the spacer isn't needed. I say this based on 2 primary groups of data.
1. Every SBC swap with an Archie kit has the flywheel effectively 1/4" further from the throw out bearing (think of it as a flywheel that is effectively 1/4" thinner).
2. Variation in pressure plates, clutch mfg, clutch style, and clutch material results in the pressure plate fingers having variations in depth of up to 1/4 to 3/8" in.

These two items have been happening for decades and no one (including myself) ever focused on it. Sometimes they needed a longer pushrod to recenter the piston in the slave cylinder, but they worked... even being 0.250" off, so there isn't really a need to fuss over a 0.030" shim...

HTOB setups have really brought these issues to the forefront (at least for me) as their range of motion is much less than the stock Fiero setup and when you push them too far, you are pulling the transmission and replacing a $75-$100 part. This is why every setup using a HTOB need to be measured as there is no consistency in combination of parts.

Thanks for all replys

I think 0,24" seems kind of mutch so I'm little bit confused where to measure the thickness. The backside of the flywheel has a balance weight an there it measures around 0.760". Where is the right place to measure?

The machined surfaces on both sides.......you can ignore balance weights.

edit: Those must have been some pretty big dents!....

[This message has been edited by Gall757 (edited 07-21-2018).]