I'm not a numbers person and my head is swimming with maths!
I think i over did it with the spacer....
Here's what i have so far:
Htob retracted: 2.30"
Htob extended: 1.43"
Clutch pp fingers : 2.10"
Htob range is .87"
Clutch face is 1.43"
Wear gap .20"
I can remove a .07" shim to make the numbers look better, but do i need to?

what engine and flywheel are you using?

3.4pr w/88 flywheel

quote Originally posted by f85gtron: 3.4pr w/88 flywheel

That should have the same stack height as the 2.4 the f23 came with, you should be fine without a spacer.

Nope. Already blew one out. It's a little short....so here i am. This time, I'll ask and measure first.
Most the hot rod sites talk of.15-.20 wear gap, but some on this site say .25. Is there something special about the stock pp and clutch that warrant the extra gap?

quote Originally posted by f85gtron: Nope. Already blew one out. It's a little short....so here i am. This time, I'll ask and measure first. Most the hot rod sites talk of.15-.20 wear gap, but some on this site say .25. Is there something special about the stock pp and clutch that warrant the extra gap?

I would be willing to bet that the tolerance of the stack height of all of the components is >.050"... where did you source your first HTOB from? many people have had problems with the parts store variety, I bought my last one at the dealership.

quote Originally posted by f85gtron: I'm not a numbers person and my head is swimming with maths! I think i over did it with the spacer.... Here's what i have so far: Htob retracted: 2.30" Htob extended: 1.43" Clutch pp fingers : 2.10" Htob range is .87" Clutch face is 1.43" Wear gap .20" I can remove a .07" shim to make the numbers look better, but do i need to?

Were these dimensions taken with the bleeder assy installed and open? There is a check valve in the HTOB that will keep it from fully compressing w/o this step. The overall range of motion is within range, so I assume you had the bleeder installed or it was a brand new HTOB.

From these numbers, I assume you have spacer around 0.47" thick because the extended and retracted (compressed) numbers are about that much different that I would expect. If you spacer isn't 0.47" then what it is?

The clutch to pressure plate finger dimension is also not typical - it normally in in the 2.3" range. You might want to double check or share what application you purchased the clutch for. A thicker disk will move the fingers closer to the engine, so that might be the case.

From the numbers you show, your setup should work fine, but I would double check the pressure plate finger dimension.

Also, if you are installing a new HTOB, they are a pain to bleed. You might do yourself a favor and while it is off the transmission, submerge the bleeder end and screw in brake fluid and cycle the HTOB a couple of times to suck as much fluid into it as possible. Then when you install it and prepare to make the engine/transmission keep the bleeder cracked as some air and fluid will likely come out. If fluid comes out as the engine and transmission are bolted together, then the HTOB should be full of fluid and make the bleeding process much easier.

quote Originally posted by ericjon262: That should have the same stack height as the 2.4 the f23 came with, you should be fine without a spacer.

The issue is most people don't purchase the clutch and pressure plate for the F23 application, they buy the Fiero version and I believe there is a difference in the pressure plate design/ratio/finger placement between the Fiero applications and the F23 ones... but no one has taken the time to fully sort this issue out.

I didn't think of that, my clutch is for an F23 application...

Eric, I think you advised me to buy a cavalier clutch, now that I think about it. I forgot when I went to buy the clutch.

Guru, it's a fiero getrag 5 speed clutch. I checked and double checked the pp fingers heights and always come up with 2.10"

quote Originally posted by f85gtron: Guru, it's a fiero getrag 5 speed clutch. I checked and double checked the pp fingers heights and always come up with 2.10"

If that is what it measures, then the rest of your setup should work well with it.

I am concerned about two things:
The wear gap,
What happens if the pp fingers bottom out on the clutch face?

Guru,
New htob, bleeder installed when measurements taken.
Currently, i have a .29 spacer and a .07 spacer installed @ .36" for the measurements I've posted.

quote Originally posted by f85gtron: I am concerned about two things: The wear gap, What happens if the pp fingers bottom out on the clutch face?

The wear gap is just there to allow the disk to wear and the pressure plate fingers to move closer to the transmission. If you install it with 0.10 gap, you will have less clutch line (time before disk wear matches clearance and clamp load on pressure plate starts to decrease). If you install it with 0.20" gap you will have more clutch life, and even more with 0.30". The key here is to balance to avoid over extending the HTOB while maximizing clutch life.

When the fingers make contact with the clutch disk center (by pushing them in too far), there will be metal on metal contact that you should here as well as the clutch will start engaging because you are now pushing it against the flywheel with the pressure plate fingers via the HTOB. So you will experience clutch release mid pedal travel, but clutch engagement again as the pedal reaches the floor. If you have this (and your setup would be more likely to given the placement of the pressure place fingers), then you either can use an adjustable banjo or a spacer between the clutch master and the front firewall to reduce pedal travel.

quote Originally posted by f85gtron: Guru, New htob, bleeder installed when measurements taken. Currently, i have a .29 spacer and a .07 spacer installed @ .36" for the measurements I've posted.

Your measurements are a little odd then, but that merely means there are HTOB setups with different extended and compressed dimensions. But this does reinforce the need to measure every setup and match the range of motion for the components you are using.

Everything is within the proper range for your setup, given your selection of parts, but be on the alert for pushing the pressure plate fingers into the clutch disk. I would also do your best to fill the HTOB with brake fluid prior to install.

Eric and guru thanks for your help.
The htob and trans are for a 2001 cavalier. I suppose most of these issues could have been avoided by purchasing the cavalier clutch and pp. Oh well, lesson learned. But, on the bright side, I'm learning ALL about htob setup and maybe I'll be able to pass some experience on down the line now.
I'm going to 're measure today and double check. I have a gut feeling the .07 spacer will end up being removed in favor of wear gap and finger to clutch interference.

i figured I'd respond to this thread instead of starting my own.

I've read a bunch of this topic and i feel stupid for not understanding it better.

I have a Camaro flywheel from fireorog turned down to .840
I have a spec stage 3+ clutch
And I am using an F23 and a .25" spacer from spec

Here's what I measured:
2.56 PP
.14 fingers
2.56 - .14 = 2.42 Bell to fingers
2.56 compressed
1.6 extended

2.56 - 1.6 = .96 range of motion
2.42 - 1.6 = .82 available travel
2.56 - 2.42 = .14 for wear

I believe this is ok? It doesn't give much for clutch wear though...

With the spacer installed it will work fine but clutch life could be reduced.
I normally target 25% of the range of motion for wear and your initial range of motion of .96 seems a little high. Normally the room for wear is in the .200" range.

If it was my car or a customer's, I would turn the spacer down to get more travel for wear.

I would not run it w/o the spacer.

thanks, youre the man