V8 Miata Drivetrains Everything behind the flywheel that takes the power to the wheels.

Newbie with trans clutch question...

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Old 06-23-2011 | 12:56 AM
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Default Newbie with trans clutch question...

I picked up a 93 Miata with a complete swap done and the guy I picked it up from said that I would have to do a hydraulic clutch system on it to get the best performance out of as the clutch slips because it does not fully engage. In cold weather or when the car is cold it works fine but when everything heats up its starts slipping. I am planning on doing a clutch at the sametime just to make sure everything is legit.

What clutch is a good recomendation? Car is dynotuned to 300rwhp... Trans is a T5 out of a 93 Mustang 5.0

Also what is a good kit to buy for the hydraulic clutch?

Has anyone done this and is there a thread with pictures I can use as reference?

Thanks for the help.
Old 06-23-2011 | 08:26 AM
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A stock Ford clutch kit will work depending on your usage. Any good after market manufacturor can provide what you need. You'll need clutch plate, pressure plate, pilot bearing and the hydrolic throwout bearing and master cylinder and plumbing. Boss Frog has a kit. Before investing in anything I would suggest contacting manufacturer's tech support line...ususaaly an "800" number to discuss usage and get recommendations......it's free and always a good idea. Hope this helps. Tony
Old 06-24-2011 | 09:02 AM
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Most Ford conversions are built using the Miata's hydraulic clutch system to actuate the Ford clutch because adding the Ford's cable system to it is a PITA. The clutch used is still for a mustang application, the only difference is that a Miata slave cylinder is pushing on the clutch fork instead of the Mustang's cable. Mustangs do not use a hydraulic throw-out bearing.

Look under your car on the driver's side of the bell housing to verify that you have a cable of a hydraulicly actuated clutch. I it's hydrolic you'll see a line running down to a small cylinder bolted to the bell with a rod that is pushing forward on the clutch fork. If it's mechanical you'll see a cable pulling on the fork from the front of the bell. If you look under the hood, a hydraulic system will have a second small master cylinder down in the driver's side corner of the firewall. A cable system will have, well, a cable there.

Both of these systems are adjustable. You may just need to take away a little preload on the clutch fork. If it's hydraulic you simply turn the bolt on the rod pushing on the fork. There is similar bolt under the bash on the pedal assembly that can accomplish the same goal. If it's a mechanical system from a Mustang there should be a "quadrant" system under the dash. Usually to adjust these more preload all you need to do is lift up on the pedal with your foot. To remove it you'd have to check out the Mustang corral or a Mustang book.

Let us know what you have and we'll move on from there.

-Jason

in both of these cases, if you tighten the preload too much you
Old 06-24-2011 | 07:29 PM
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jeggs sells a hyd. throwout bearing, comes with lines and a bleeder kit and will sell you a master cyl. to match the bearing. i think it comes to less than $300.00. instructions are ok
Old 06-25-2011 | 01:35 PM
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Havent had a chance to get under th car yet but as soon as I do I will let you guys know. I have had this car for a week and half and have been pulled over twice already. This is not a good start.
Old 06-26-2011 | 09:49 AM
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I am having similar issues. I have Martin's master cylinder and a new stock 1993 miata slave cylinder. mounted with martins angle L bracket to the bellhousing. Have a hole machined 7/8" proximal to the throwout pivot on the clutch fork. If I adjust too much off the clutch fork I have shifting issues (grinding) If I adjust too much preload I have clutch slippage? Is there different pressure plates for the 5.0 ford. the trans/clutch/pressure plate are fairly new w/o much wear and all is out of 1990 gt 5.0
Old 06-26-2011 | 02:36 PM
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Originally Posted by 93v8bean
I am having similar issues. I have Martin's master cylinder and a new stock 1993 miata slave cylinder. mounted with martins angle L bracket to the bellhousing. Have a hole machined 7/8" proximal to the throwout pivot on the clutch fork. If I adjust too much off the clutch fork I have shifting issues (grinding) If I adjust too much preload I have clutch slippage? Is there different pressure plates for the 5.0 ford. the trans/clutch/pressure plate are fairly new w/o much wear and all is out of 1990 gt 5.0
Called the previous owner of my car and this is the same problem with mine actually... Adjust it one way and it grinds gears and the other the clutch doesnt grab. The swap on my car only has 5k miles total... I wonder if I even need a new clutch? I just need it adjusted right and it will probably be all good.
Old 06-26-2011 | 05:24 PM
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I measured the "throw" of the metal clutch fork at the entry/exit point on the bellhousing and I get 1inch from foot to the floor fully engaged to foot pedal released. Let me know if that is how much is normal. I'll upload pics tonight.
Old 06-28-2011 | 08:20 AM
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If the car is using the traditional "Miata slave on the bell with angle iron" method you're probably experiencing a combination of bad pushrod angle and bellhousing flex, both of which lead to reduced throw at the fork. To get the maximum throw, many of us have found a combination of bracing the slave against the trans and moving the hole the pushrod pushes on inward on the fork has been very successful.

On the other end f the system, you can remove the bumpstop and unused switch from the top of the clutch pedal assembly to give you more throw on that end. The pedal also has some small adjustments that can be made where it's pushrod goes.

Even though a few hydrolic thow-out bearing options exist for the Mustang T-5 I have never heard of one leading to anything other than frustration. Granted, no one has tried in 5 years o so, maybe the technology has improved.

Pictures' worth a 1K words:





More can be found here, near the bottom of the page:

Click me now!!!!

-Jason
Old 06-29-2011 | 03:00 PM
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Default slave cyl.

maybe that hyd. throwout bearing is my shifting problems. what slave cyl. and size master do you use. thanks for posting those photos they are very helpful
Old 07-02-2011 | 11:32 AM
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Help we have the motor and trans out. Starting to do the slave on the bellhousing and I need to know what slave to use. Also where did you come up with that threaded adjustment rod. Any info will be helpful
Old 07-02-2011 | 05:20 PM
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Stock Miata slave cylinder. My adjustment bolt appears to be a grade 8 bolt with the head cut off, an old rocker arm pivot ball, & a nut.
Old 07-02-2011 | 06:57 PM
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Thanks, I had thought of the bolt but didn't know about the rocker arm pivot.From the photos I thought it might be a stock Miata slave, but having it confirmed helps a great deal.
Old 07-12-2011 | 01:50 AM
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Does anyone have any idea 's on what is the best push rod to use for actuall fork , like length or material i have seen the 7/8 ball grind but what is used to engage the clutch fork with the double nut on both sides.
Old 09-02-2011 | 04:38 PM
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A Chevy rocker fulcrum.

-Jason
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