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 Post subject: Clutch Question
PostPosted: November 2, 2018, 1:50 pm 
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Location: BC, Canada. eh?
Question for you guys -

I'm using a Focus Zetec engine, mated to a Ford T5 WC (non-V8 version) trans, via a Fidanza flywheel, Mustang II clutch assembly, and a RAM 78136 hydraulic throwout bearing/slave.

Yesterday I centered the friction plate (had to make an alignment tool, as I didn't have one) & torqued the new clutch assembly down. As is, I believe, normal, the clutch fingers moved in toward the friction plate as the clutch was torqued down.

In all the clutches I've worked on in the past, I've never had to actually put in a new friction plate - it was always a matter of just putting the original back together (usually a result of replacing a worn pilot bushing or something), so installing an entire new assembly is new to me.

I'm concerned about how far the fingers moved in when the clutch was torqued down. On those old clutches I've worked on, there appeared to be, say, 3/4" to 1" of travel available to the clutch fingers before they could bottom out on the friction disc hub.

In this new one, though, the fingers only have a total of 0.276" - 0.286" (it's difficult to measure accurately, but I think the higher value is most accurate) of travel available before they bottom out on the friction disc hub.

So (finally) - my question: Does this seem like enough free travel range to release the clutch fully?

Thanks in advance for any insight you guys can offer!!!

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 Post subject: Re: Clutch Question
PostPosted: November 2, 2018, 1:56 pm 
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What are the specific OE applications (year range, make, model, and engine) for the pressure plate, clutch disc, and flywheel? I wouldn't be able to say either way with certainty, without at least comparing photos and specs between what they were originally being paired with and what they are currently being paired with. If the OE flywheel for this clutch and the current flywheel being used are both fully flat faced or of the exact same pressure plate mounting surface protrusion over the friction surface, and the pressure plate and clutch disc are both from the same set rather than mix and matched, and you're certain that all the components are indeed what they are supposed to be, then it seems that this might just be the way it is. However, if the pressure plate was designed for a flywheel that has any amount of additional mounting surface protrusion over the friction surface, or the clutch disc is thicker than OE for the pressure plate, then what you're seeing would be incorrect.

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 Post subject: Re: Clutch Question
PostPosted: November 2, 2018, 2:51 pm 
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Location: BC, Canada. eh?
The engine came from a car with an automatic, so there's no original flywheel to compare to. However, the Fidanza flywheel is specifically designed for this engine (and the Ford Focus application) and, according to Fidanza at least, has identical deck-height specs to the original flywheel.

The decision to use the Mustang II clutch assembly was based on the experience of others who have mated a T-5 to a Zetec, and according to Quad4Rods, which produced the bell housing. As those who did this in the past probably all used stock flywheels, the difference of using the Fidanza would seem to be the "wild card". I've been relying on Fidanza's claim that the deck height is identical to that of an original Focus Zetec one. IF that's true, all should be correct.

It's just that I've never seen a clutch with fingers that close to the driven plate before. I have VERY limited experience with this issue. From what little I've found on the internet, common clearance on other car applications seems to range from 1/4" to 1/2", so maybe I'm okay. All the components are brand new, so I would expect the fingers to be substantially lower than on a somewhat worn disc. I just don't know how low is too low!

I'd hate to reinstall the engine, hook everything up, bleed the clutch, etc. only to discover the clutch won't release, or that it drags.

I'm hoping someone else will recall whether this seems relatively normal for a new clutch/disc/flywheel install. If it is, I'll go ahead & put it all together & hope for the best. If it's not, I'll have to come up with a solution. A friend suggested having a machine shop mill off material beneath the flywheel's steel friction insert to lower the latter, but that seems like a REALLY aggressive solution, and if it wasn't appropriate it would destroy a breathtakingly expensive flywheel.

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 Post subject: Re: Clutch Question
PostPosted: November 2, 2018, 4:38 pm 
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That doesn't look right Mike.
The clutch side surface of the flywheel in my limited experiences are flat right across. When it is resurfaced the whole area is ground. I can't ever recall a "step" on the clutch side of a flywheel, but then again, limited experience.
Your throwout bearing will have a lot more travel than what you show there.
Is your clutch plate too thick for that pressure plate? Is that the correct pressure plate for that clutch plate? The clutch plate should also reference "flywheel side" to indicate the proper installation.
Need to verify that before assembly.
Personally I would not put that together with only that amount of finger travel, but that's only my opinion, I could be wrong you know (but my spidy senses are tingling).

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 Post subject: Re: Clutch Question
PostPosted: November 2, 2018, 4:57 pm 
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Joined: December 29, 2007, 10:41 pm
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Location: Vancouver, BC
Mike,
I still have the stock Focus flywheel, pressure plate and disc somewhere in the garage. I can bolt it all up on Sunday and take some pics for you, or if you want I can pack it up and send it to you (unless you're heading over the mainland sometime soon).

Rod


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 Post subject: Re: Clutch Question
PostPosted: November 2, 2018, 5:20 pm 
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It's not uncommon. especially on newer vehicles, to have a stepped face flywheel. It appears that the Zetec flywheel is as such while the Mustang II would not have been...But that should actually result in less clamping force and let the spring fingers sit further away from the disc than it would on a MII flywheel. So unless the MII disc is thicker than a Zetec disc by more than the step thickness, something doesn't seem quite right here.

Might the disc be installed 'backward' from what it should be? Might any part of the pressure plate (not counting the cover) be hanging up on the stepped portion of the flywheel, such that it's not extending with full force against the disc?

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 Post subject: Re: Clutch Question
PostPosted: November 2, 2018, 6:09 pm 
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That's my guess also. Remove the pressure plate and measure the od of the clutch and pp ring.
Test fit the PP without the clutch to check for ring to step shoulder clearance.

The clutch could be 8.5, 9, or 9.25 with a 10 tooth spline even if the part number on the box is correct.
You might also try the zetec pp instead. All you are after is a clutch that will fit the input shaft and have close to the same friction surface. No need to swap the pp too.

From what I can tell, the clutch is installed with the small plate side facing out as it should be.

That amount of finger to disc gap is not normal even if it might work or has worked for others.
Here is a pic of my 4.3l v6 with the fiero flywheel and 2002 cobalt pp. Apples to oranges but it provides a general idea of normal!?! :shock: :?


Attachments:
pp 004.jpg
pp 004.jpg [ 315.69 KiB | Viewed 1797 times ]

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Last edited by Miatav8,MstrASE,A&P,F on November 2, 2018, 6:15 pm, edited 1 time in total.
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 Post subject: Re: Clutch Question
PostPosted: November 2, 2018, 6:14 pm 
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Miatav8,MstrASE,A&P,F wrote:
No need to swap the pp too.
Not necessarily. The release bearing may be of a different functional diameter or (radius vs flat) style, as well as the clutch height vs release bearing reach might not be compatible.

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Last edited by Driven5 on November 2, 2018, 6:18 pm, edited 2 times in total.

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 Post subject: Re: Clutch Question
PostPosted: November 2, 2018, 6:17 pm 
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The stock pp is normally used with this conversion.
The fingers are not an issue either way.

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 Post subject: Re: Clutch Question
PostPosted: November 2, 2018, 9:53 pm 
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Dumb question: Are you sure the disc is in the correct way? Engine side to engine I mean.

You could always put the flywheel/clutch in a press and check how much movement it takes on the fingers to release fully. Some take very little movement, but 0.25" seems a bit tight.

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 Post subject: Re: Clutch Question
PostPosted: November 3, 2018, 5:15 am 
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You are looking for .030 to .040 air gap between the disc and the flywheel with the clutch pedal pressed.
Diaphragm pps generally have a ratio of 3.5:1 for a little less than 0.500 movement toward the flywheel.
This puts the ends of the fingers about .250 above the pp cover.

I didn't find any straight answers for converting the fiero to use an f23 trans with the f23 hrob instead of an external slave but using the fiero master and pedal ratio. There were more than a couple failures from not checking, so I had to measure everything and figure it out for myself.

A good way to check required pedal travel for the bore used is to put the car on stands, let idle in gear, then find the sweet spot and measure remaining distance to the floor. You can then add a travel stop or switch master bores.

Somewhat related, but after some maths, it looks like i will be able to use the spitfire master with the s10 slave and no pedal mods. The triumph pedals are low ratio compared to normal pedal designs.

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 Post subject: Re: Clutch Question
PostPosted: November 3, 2018, 1:05 pm 
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Location: BC, Canada. eh?
Thanks for all the replies!

I'm going to have to pull the clutch again to make sure everything's right, and to put blue Loctite on the flywheel bolts (I used the ARP lube, instead of Loctite, as ARP requires, but others recommend using the Loctite and maybe the lube under the bolt heads only).

RAM advises the total compression travel of their hydraulic T/O bearing is .500", and to ensure the required movement is that much or less, to avoid blowing out its seals. They also require .150" to .200" clearance between the bearing and fingers, as part of the .500". Theoretically, then, my available travel of .286", plus a .200" freeplay gap, would give a total of .486", within the working range of the bearing.

It's all very confusing! The clutch set I've used is the same as those who have done this conversion before, but unfortunately I don't know if they ran into this issue.

I'll be pulling it all apart again today, and taking a closer look.

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 Post subject: Re: Clutch Question
PostPosted: November 3, 2018, 7:23 pm 
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I apologize for the length of this post, but it's enormously complicated & this is the best I can do to try to explain it in as few words as possible.

Unfortunately, the whole clutch assembly has to be an assemblage of mix-'n-match parts, because I'm using a Ford T-5 trans. The input shaft on a T5 trans is a 10-spline, whereas the Focus (Zetec) has a 23 spline, so I can't use a Focus friction plate.

I have a Ford Mustang II clutch assembly, a Fidanza aluminum flywheel with a hardened steel friction surface insert, and a 9" diameter 10-spline friction disc. While there's no "this side toward engine" legend anywhere on it, I'm fairly sure the protruding hub has to face outward, as it would contact the flywheel bolt heads, etc. if it was installed with this hub facing inward.

I've disassembled & reassembled it dozens of times, and the issue has to be a) the thickness of the friction disc (.3300" thick - Motorcraft XS41-7563-RB disc, made by Sachs, but labeled as Motorcraft), b) the thickness of the flywheel's friction surface, or c) the thickness of the driven plate's friction surface.

I can't realistically see the flywheel being the issue, as it's the appropriate flywheel specific to this engine, and at least according to Fidanza, it has precisely the same working dimensions as the OEM flywheel, including deck height, friction surface height, etc. Supposedly, it's a bolt-in identical unit, except it's 8 pounds vs. the Focus' 24 pound unit.

Here's what I've found - when the clutch bolts are just finger tight, and the friction plate is just touching both surfaces, there's about a .100" gap between the flywheel clutch mating surface & the clutch's mating surface.

Cinching the bolts down (and torquing them) the extra .100" causes the clutch fingers to move in about .800". This is about 2/3 of their total available travel (roughly 1.120" of travel before they contact the friction disc hub).

With NO friction disc installed, there's about .1275" gap between the two friction surfaces (as best I can measure).

When the (.3300"-thick) disc is installed & the clutch is torqued down (thereby compressing the clutch basket's spring an extra .2025", to accommodate the friction plate's extra thickness), the fingers move inward about .800".

So - according to my math, for each .100' the clutch spring compresses, the fingers move inward roughly .400".

Therefore, to retract the spring by .2025" (so the friction plate just contacts the surfaces), I'd need to compress the fingers .810".

I only have a little over 1/3 of that amount of finger travel left when everything's torqued down.

Clearly, I have a serious problem.

Possible solutions would seem to be:

1) Putting thin (say, .150" thick) spacers between the clutch basket & flywheel, increasing my finger travel by .600"
2) Finding a thinner friction disc (hard to do, as NONE of the manufacturers provide this dimension)
3) Machining the flywheel friction surface down, say, .150" Unfortunately, Fidanza says this isn't feasible, as it's extremely hard steel
4) Machining the flywheel's inner surface, where the steel friction plate is attached, by a similar amount (I suspect this might compromise the flywheel's strength, though)
5) Obtaining another clutch driven plate assembly, with a lower friction surface height (again, this is a dimension that manufacturers don't provide).
6) ???

I am WIDE open to any suggestions, and I REALLY appreciate your consideration!!

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 Post subject: Re: Clutch Question
PostPosted: November 3, 2018, 9:17 pm 
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There are custom clutch manufacturers out there. Maybe contact them about a custom disc?

Use caution with spacers. You do not want to lose any clamping force on the rotating parts especially if you only have an aluminum bellhousing.

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 Post subject: Re: Clutch Question
PostPosted: November 4, 2018, 4:06 am 
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Interesting development - I contacted one of the contributors here ("RM Eight", from Winnipeg, Manitoba), as he recently finished his Zetec-engined, T-5 transmissioned Locost.

As it turns out, he recently had to pull his clutch (fouled due to a leaky rear main seal), and took pictures of the assembly.

I don't think he'll mind if I cross-deck one of his photos here -

Attachment:
bruce clutch 1 small.jpg
bruce clutch 1 small.jpg [ 688.97 KiB | Viewed 1681 times ]


vs. mine -

Attachment:
clutch small 1.jpg
clutch small 1.jpg [ 326.11 KiB | Viewed 1681 times ]



Surprisingly, his looks pretty much exactly like mine - the clutch fingers are well below the level of the pressure plate, as mine are, and his clutch (aside from the leaky rear main seal, which has nothing to do with the clutch itself) works great. Aside from my Fidanza flywheel, our parts list is essentially identical.

It gives me hope! Unfortunately, I've blown apart the entire car in preparation for frame paint, so I can't install the engine & connect the clutch hydraulics to see if it all works.

Instead, I plan on mocking up a tool that will compress all the clutch fingers manually, and see if the friction plate releases. IF it does, I'm good to go. If not, another re-think will be required...

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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.

http://zetec7.webs.com/


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