I found a new old stock F40 transmission on the local classifieds. It has never been used and came with a 6 puck clutch and flywheel, which weren't used either but it seems that at least the transmission was left out in the weather a fair bit. I installed this setup on my 2006 Grand prix and started to bleed the clutch master cylinder and slave, but was quickly disappointed when the clutch pedal gave way when still trying to bleed the system. That was followed by a steady stream of fluid coming out the bottom of the trans. So either the slave cylinder gave way because it was 15 years old but never used??? Or possibly the slave cylinder had to overextend because my flywheel is to thin? Or was there supposed to be some spacer between the throwout bearing and clutch fingers? Any suggestions are welcome. I'm hoping to drop the trans this thursday night and I have a new slave on its way to install. But maybe I need to do some measuring first??
Never install a HTOB transmission without measuring the stack height to the fingers and the range of motion for the HTOB. Lots of people have over extended them due to not measuring first.
Specs solution for the F40/3800 was based on a full thickness Camaro flywheel, clutch disk with a flipped hub (to increase spline engagement), a pressure plate with altered finger placement, and a HTOB spacer. Far from an ideal setup and easy to accidentally swap out any of the 4 parts for similar but not the same and run into issues.
Thanks for responding Fieroguru. That's all new info to me, guess I lacked the research. Another piece of the puzzle is that I originally installed a 5 speed 282 from an 89 Grand Prix, and am still using that master cylinder. Not sure if that displaces too much fluid or not. But I definitely need get an HTOB spacer, and didn't flip the clutch around for better spline engagement. I believe it is a stock camaro flywheel with the spec clutch. Where do you recommend getting the spacer? Is the air gap the same as stack height? Just watched a video on measuring the air gap (working manual transmissions is new to me).
[This message has been edited by dnthmn87 (edited 08-25-2021).]
So I got the transmission out last night and measured from the clutch fingers to the block, 3'' exactly. Bellhousing to TOB was 2'' 7/8 with the slave cylinder compressed with the bleeder installed and open. So 1/8" of an inch is actually ideal, right? Could the seal of the original one just have just blown out because it was 15 years old and sat out in the sun for a couple years? note, my throwout bearing didn't compress even half as much as the one in the video that I watched on how to do this, but it was a different transmission. But it does compress at least 1/4'', using the new slave.
Forget my last post, it is 3.5 inches from the bell housing mating service to the compressed slave cylinder, only 3” from the pressure plate fingers to the block, so I’ve got 1/2”… I’ve found 1/4” spacer so hopefully that’ll be good enough 🤷♂️.
A stock F40 HTOB has about 0.90" of available travel. You want about 25% of this to be for wear (gap between pressure plate fingers and fully compressed HTOB) and 75% of this for travel to release the clutch.
You want something around 0.225" for wear so you have about .675" for clutch release travel. Having 0.5" for wear is a bad thing.
So shouldn't the .25" spacer make it good enough? I installed that spacer with a new slave and put it together. I was bleeding the clutch and it was starting to feel pretty good, then POP!!! The slave blew out again!!! Grrr Now what?
[This message has been edited by dnthmn87 (edited 10-21-2021).]
For sure. I’ll probably rope someone else in to help measure this time too. Is it possible that my master cylinder is displacing to much fluid? Pushing the slave out too far? Or should the clutch fingers bottom out on something?
I'd like to join this conversation if I may. I too have an F40 6 speed. I was not aware of the 0.90" of travel assigned to the TOB. With no hydraulic fluid in the bearing it appears spring loaded and upon compression will collapse 1/2". Where is the 0.90 dimension measured from? The face of the bearing before it is collapsed? The understanding that I'm taking away from this conversation is that the fingers of the clutch should be depressing the bearing 1/4 of its travel, or 0.225". So for setting up the location of the clutch fingers, would it be accurate to say that the fingers should be 0.675"away from the face of the TOB before any fluid is added? I would really appreciate some clarity here. Thanks.
Or, having slept on it, it occurs to me that that the "free" space before the surface of the TOB is 0.225", not 0.675". in that manner as the disk wears the clutch fingers tend to grow and the 0.225" allows for that growth without releasing the clutch. Am I close?
Or, having slept on it, it occurs to me that that the "free" space before the surface of the TOB is 0.225", not 0.675". in that manner as the disk wears the clutch fingers tend to grow and the 0.225" allows for that growth without releasing the clutch. Am I close?
I think you're right Kenn but im not the expert. OK new measurements with a .25 spacer and another new slave cylinder. Its 3.312" to the compressed slave/tob. And I double checked the pressure plate fingers to the bell housing mating surface with a new straight edge, still get 3". So the air gap is still a little too much? Side note- My clutch pedal has a lot more travel than my CTSV and another car I compared it to. I had to make my own clutch pedal mount on a car never intended to have a stick shift (2006 Grand Prix) and I feel like the placement of the pedal gives it more travel than it should. Both cars I glanced at have a bump stop of sorts so the pedal doesn't just go to the floor. Last time it blew out the slave it just felt like the pedal can move too far, its not even close to an OEM setup, I guess I should try to find a G6 and compare master cylinders to what I have and see how much the pedal travels with pressure. Even if I get the air gap perfect, I still might add my own bump stop so I can control the amount of pedal travel.
Ok i've got a bad idea to throw out for debate. I''ve got a .31'' gap between the TOB and clutch fingers. Its supposed to be .22". I can't stack 2 spacers like the one i'm using, theyre not designed to work that way. So what if I found a .10" washer the same shape as the face of the TOB and bonded/welded the washer to the TOB to achieve a smaller gap? Seems risky right? I still plan to reduce the pedal travel and see if the clutch still gets pushed in far enough either way.
If you are using the spacer that slips over the nose of the HTOB face, then you can install a small shim between the spacer and the HTOB nose.
With this application being a hodgepodge of parts in a non-fiero chassis with an unknown master and unknown dimensions of pedal pivots and rod attachment. You might be better off starting with a known good setup. Can you adapt the G6/F40 master and clutch pedal to your W-body?
You would still need to make sure you have the pressure plate fingers in the proper postion of the HTOB range of motion.
Guru, when you refer to the "spacer" that slips over the htob, are you referring to the spring-loaded face of the htob? Did you remove that on your build? Do you know what purpose it serves? I was reading on the mr2 forum that the proper relationship of the clutch fingers was to just touch that face. the 1/2" spring load is to take up the extension of the clutch fingers as the disk wears. Does this make any sense to you?
Guru, when you refer to the "spacer" that slips over the htob, are you referring to the spring-loaded face of the htob? Did you remove that on your build? Do you know what purpose it serves? I was reading on the mr2 forum that the proper relationship of the clutch fingers was to just touch that face. the 1/2" spring load is to take up the extension of the clutch fingers as the disk wears. Does this make any sense to you?
Ken
My setup was properly designed (I designed my flywheel to match my clutch disk/pressure plate combo) so I have never needed to use a spacer on my car. Customers cars that used parts from others is where I learned about all the fun with spacers...
Spec sells a spacer that presses on the face of the HTOB (the face is the part of the HTOB that touches the pressure plate fingers). You can install a small shim between this spacer and the HTOB to effectively make the spacer thicker.
There is no set space/gap that is universal across all makes, models, and applications... it all depends on range of motion in the HTOB as well as the travel of the pressure plate fingers. 1/2" is way too much of a gap for clutch disk wear for the F40... use it and you will blow out the HTOB. 1/4" gap is much more ideal.
Guru, when you refer to the "spacer" that slips over the htob, are you referring to the spring-loaded face of the htob? Did you remove that on your build? Do you know what purpose it serves? I was reading on the mr2 forum that the proper relationship of the clutch fingers was to just touch that face. the 1/2" spring load is to take up the extension of the clutch fingers as the disk wears. Does this make any sense to you?
The spacer I found was from ZZP and goes between the back of slave cylinder and the transmission. I made an addition spacer to go with that one to achieve a .21 air gap. I also added a bump stop to the pedal as I felt the travel was too far. Put it all back together and bled the pedal successfully without blowing out the slave(thankfully). Started the car and pushed the clutch pedal in and it makes a terrible vibrating/grinding sound! It makes the sound when its barely pushed in at all.... Brand new slave/throwout bearing. I'm about ready to set this car project on fire and claim the insurance money
Please take what I about to say with a grain of salt or an aspirin .F 40 does not have a slave cylinder.It has a hydraulic through out bearing.If the F40 came with the little black "Y" thing,you will need one.It is your auto bleeding system.This little black "Y" thing plugs into the clutch at the bellhousing.If hydraulic fluid came out of the bellhousing then the trough out bearing is ruptured, and you need a new one.
I was concerned about this very thing with my LFX/F40 setup. TheFierp clutch master cylinder piston diameter is significantly larger that the clutch master cylinder used in vehicles that came with an F40. This means that the Fiero master pumps more fluid. That has the potential to do 2 things. 1. Make the clutch pedal harder to push. 2. Overextended the hydrolic throw out bearing. I am trying using a Saab master cylinder. I posted about it on my thread https://www.fiero.nl/forum/...2/HTML/142132-1.html It is on the second to last page.
The spacer I found was from ZZP and goes between the back of slave cylinder and the transmission. I made an addition spacer to go with that one to achieve a .21 air gap. I also added a bump stop to the pedal as I felt the travel was too far. Put it all back together and bled the pedal successfully without blowing out the slave(thankfully). Started the car and pushed the clutch pedal in and it makes a terrible vibrating/grinding sound! It makes the sound when its barely pushed in at all.... Brand new slave/throwout bearing. I'm about ready to set this car project on fire and claim the insurance money
After reading your posts again, I still don't know what master cylinder you used. Do you know what car it was made for and the piston diameter?
Master cylinder is from an 89 Pontiac grand prix, my first setup was with the 5 speed/282 getrag from that car. That master is new as is the HTOB/Slave unit. Yes I have the Y shaped connector that plugs into what Ive been calling the slave cylinder aka HTOB. This time its not blown out, but I believe Ive added too many spacers because now when its bolted together the clutch is disengaged. I went back out after my last post to try putting it gear despite the awful noise, and when I let out the clutch nothing happens. In fact with the clutch pedal released I can shift gears while the car is running.... I don't understand how i'm so off while doing the air gap measurements to determine how much spacing I need. But either way i'm pretty sure the pedal had too much travel which was why I was overextending the TOB. Gonna tear it apart for the 3-4th time (lost track how many times) and re-measure the air gap and hopefully get the right spacer in there and with the bump stop in place it SHOULD finally work out.... Anyone have a guess as to how much spacer I'll likely have to remove to NOT have the clutch disengaged when bolted together? I've got a .25" and a .10"
Master cylinder is from an 89 Pontiac grand prix, my first setup was with the 5 speed/282 getrag from that car. That master is new as is the HTOB/Slave unit. Yes I have the Y shaped connector that plugs into what Ive been calling the slave cylinder aka HTOB. This time its not blown out, but I believe Ive added too many spacers because now when its bolted together the clutch is disengaged. I went back out after my last post to try putting it gear despite the awful noise, and when I let out the clutch nothing happens. In fact with the clutch pedal released I can shift gears while the car is running.... I don't understand how i'm so off while doing the air gap measurements to determine how much spacing I need. But either way i'm pretty sure the pedal had too much travel which was why I was overextending the TOB. Gonna tear it apart for the 3-4th time (lost track how many times) and re-measure the air gap and hopefully get the right spacer in there and with the bump stop in place it SHOULD finally work out.... Anyone have a guess as to how much spacer I'll likely have to remove to NOT have the clutch disengaged when bolted together? I've got a .25" and a .10"
Here is the problem in a nutshell. The master cylinder you chose has a piston diameter of about 22mm. The HTOB you are using is designed to work with a piston diameter of 15mm. Your master cylinder pushed over twice as much fluid as is called for. By comparison, the stock Fiero master cylinder has a piston size of 17mm. Although it does push 30 % more fluid than is called for, it can be spaced out to kinda work, although not as designed. The master cylinder used on the 2006 Saab 9-3 (also used on the 2014 Buick Verano) has the correct size piston, but requires adapting for the hydraulic line and linkage (see my setup as noted in previous comment above). Good luck whatever you decide to do.
