Clutch- what have I done

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digithead

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So last Fall my faithful 351C spun a low main bearing in back of motor. I had a good pro shop rebuild and stroke it to a 408. Its dyno'd at 460HP/500FPT.

I have a local shop I use a lot for car maintenance, thats good to me, reinstall the rebuilt motor. Since I had motor rebuilt I figured we gotta put in new clutch and pressure plate that would be stupid not to. I order from Summit Racing at McLeod StreetPro 11" 10 spline clutch and pp. My logic, be it right or wrong, was that I now own almost 500HP mustang and stock clutch may vaporize quick if I enjoy dumping it (jury is out on that). So Now that motor is in, I get in car and push clutch pedal and holy crap thats hard to press!   The motor dude told me to just buy a stock clutch and pp at local auto parts store but like a idiot I didnt listen. I seriously didnt think one step up in clutch would be that much noticeable but dear Lord you can really feel it.  What do you say? Its ok if you tell me I'm a idiot sometimes I learn best at the school of hard knocks.  I may have to bite bulllet and pay for new clutch install, I dont have a lift.

https://www.summitracing.com/parts/mcl-75111

 

73pony

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I would not think that this clutch would require that much additional pressure compared to a stock one. Odd. I will say this. I went with a stock style clutch and I wish I hadn't. I will have to change mine out when I have time as I can spin the clutch easily.

 

OzCoupe72

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That's no good but shouldn't be that much heavier

Perhaps firstly need to check there is no binding anywhere, remove slave cylinder push rod and check the clutch fork moves freely and has not come off the pivot if there is one. Check at the pedal end as well but don't forget to open the bleeder so you don't push out the slave cylinder piston. Other things to try is changing fluid in case water got in it.

If there are no binding or fluid issues then you could try a smaller bore master cylinder although that will lengthen pedal travel I think.

Other option is a remote booster servo between master and slave cylinder

I would also contact Macleod Racing to get their advice seeing as it's their product

Good luck

 

barnett468

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what disc are you using?

all mcleod and ask them what pressure the plate is.

Do you have the stock clutch linkage?

 
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digithead

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That's no good but shouldn't be that much heavier

Perhaps firstly need to check there is no binding anywhere, remove slave cylinder push rod and check the clutch fork moves freely and has not come off the pivot if there is one. Check at the pedal end as well but don't forget to open the bleeder so you don't push out the slave cylinder piston. Other things to try is changing fluid in case water got in it.

If there are no binding or fluid issues then you could try a smaller bore master cylinder although that will lengthen pedal travel I think.

Other option is a remote booster servo between master and slave cylinder

I would also contact Macleod Racing to get their advice seeing as it's their product

Good luck
I'm confused, this is all mechanical linkage?

 

digithead

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what disc are you using?

all mcleod and ask them what pressure the plate is.

Do you have the stock clutch linkage?
Yes I do. And its all same hardware as when we pulled motor out last fall to have engine rebuilt. Only change in new clutch,PP, and throw out bearing

 

digithead

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what disc are you using?

all mcleod and ask them what pressure the plate is.

Do you have the stock clutch linkage?
Its a McLeod StreetPro Clutch Kits 75111

 

barnett468

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what disc are you using?

all mcleod and ask them what pressure the plate is.

Do you have the stock clutch linkage?
Its a McLeod StreetPro Clutch Kits 75111
i know that because it was in your previous post but unfortunately that only tells me it is an 11" setup. i need to know the specific answers to ALL the questions before i can help you.

 
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Yes the heavier duty larger clutch has to be more difficult to push in or no benefit. The mechanical advantage in the clutch linkage stays the same so it will be more difficult to depress the pedal. I use to build my own pressure plates and would use heavier die springs to replace stock ones. Some clutches only had 6 springs in the Borg & Beck style clutch like our cars came with. I would go to 9 springs and stronger. You could not sit through a red light without having to put out of gear and let off the clutch, lol. Your left leg will get a work out. We use to cruise every Saturday night and gives you a workout for sure.

The first one I did was only a 9" for a flathead Ford that would slip a stock clutch. The first time I took the car out and dumped the clutch it ripped the lining off of the brand new stock disc. I had to go to a Shafer, spelled wrong, brand bonded disc then it would pop axles or u joints, lol. A Hurst Lineloc helped that situation by being able to take all the slack out before dropping the clutch.

Another thing that might happen if you let the car sit and there is high humidity is that the disc might stick to the flywheel and pressure plate. If is does you might have to pull to un stick it.

The later model mustangs did have slave cylinders and used a cable system. Our cars have the pivot balls and Z bar with hard linkage so when you put the heavier clutch in you will notice the difference for sure.

David

 

Don C

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+1 on the left leg workout, I've had a couple of those.

Is the clutch assist spring still connected under the dash? Is the correct return spring on the z-bar?

 
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You may find that the clutch linkage has enough slop and play in it that a linkage overhaul would significantly improve the feel and resistance. The holes get egged out and the bushings split and fail. It can all be removed without the need for a lift. My clutch is notably heavier than yours, but is more than manageable. You will get used to it if the linkage isn't binding up

 

OzCoupe72

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That's no good but shouldn't be that much heavier

Perhaps firstly need to check there is no binding anywhere, remove slave cylinder push rod and check the clutch fork moves freely and has not come off the pivot if there is one. Check at the pedal end as well but don't forget to open the bleeder so you don't push out the slave cylinder piston. Other things to try is changing fluid in case water got in it.

If there are no binding or fluid issues then you could try a smaller bore master cylinder although that will lengthen pedal travel I think.

Other option is a remote booster servo between master and slave cylinder

I would also contact Macleod Racing to get their advice seeing as it's their product

Good luck
I'm confused, this is all mechanical linkage?
Apologies for the confusion, not having a manual car assumed it was hydraulic control as all of our early local V8 falcons are, is there a hydraulic conversion done on these cars? Might be a way to go for a heavy clutch?

 

barnett468

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Apologies for the confusion, not having a manual car assumed it was hydraulic control as all of our early local V8 falcons are, is there a hydraulic conversion done on these cars? Might be a way to go for a heavy clutch?
a hydraulic system only eliminates friction cause by the mechanical linkage so it will not make a big difference in the amount of force required to depress the pedal.

 

Hemikiller

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At this point, you have two choices: live with it, or change it to a stock pressure plate. I've driven the HD clutches and they can get tiring. It's the entire reason why Centerforce was created; to give you reasonable pedal pressure with excellent clamping. That said, the Long style PP in our cars has a centrifugal assist, with greater clamping at higher RPMs, which Centerforce made work on a diaphragm style clutch.

 

boilermaster

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Digithead,

Suck it up big boy,

The way I look at it you can rollerize your complete clutch release mechanism (2 roller bearings at the

pedal assembly, heim joints on the rod ends and spherical bearings at the z bar.

if you do all of this it will get you back to the stock feel with the wimpy pressure plate.

I did all of the rollerizing before I went to the 408.

Boilermaster

 

barnett468

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1. At this point, you have two choices: live with it, or change it to a stock pressure plate.

2. I've driven the HD clutches and they can get tiring. It's the entire reason why Centerforce was created; to give you reasonable pedal pressure with excellent clamping.

3. That said, the Long style PP in our cars has a centrifugal assist, with greater clamping at higher RPMs, which Centerforce made work on a diaphragm style clutch.
Actually, he has more choices than that. The main one being that he can find out what pressure the plate is then get a lighter one that is still heavier than stock. This is why I asked him to contact mcleod and get that information for me.

2. The finger weights on the centerforce clutches can get stuck on the fingers or literally fall off due to the ring that holds them on breaking. All the knowledgeable people I know that use a centerforce clutch for racing remove the weights.

3. The mcleod pressure plate he has is not the "centrifugal assist" type.

He will gain nearly nothing by switching to a diaphragm plate.

 
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barnett468

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The way I look at it you can rollerize your complete clutch release mechanism (2 roller bearings at the

pedal assembly, heim joints on the rod ends and spherical bearings at the z bar.

if you do all of this it will get you back to the stock feel with the wimpy pressure plate.
No it will not.

 

digithead

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Digithead,

Suck it up big boy,

The way I look at it you can rollerize your complete clutch release mechanism (2 roller bearings at the

pedal assembly, heim joints on the rod ends and spherical bearings at the z bar.

if you do all of this it will get you back to the stock feel with the wimpy pressure plate.

I did all of the rollerizing before I went to the 408.

Boilermaster
Thanks for the advice, makes sense. Is there some kit out there or did you basically pull it all out and find bearings that fit?

I've never pull pedal/linage assembly so I am assuming its all just simple bushings, so you figured out bearings would be better.

 

barnett468

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Digithead,

Suck it up big boy,

The way I look at it you can rollerize your complete clutch release mechanism (2 roller bearings at the

pedal assembly, heim joints on the rod ends and spherical bearings at the z bar.

if you do all of this it will get you back to the stock feel with the wimpy pressure plate.

I did all of the rollerizing before I went to the 408.

Boilermaster
Thanks for the advice, makes sense. Is there some kit out there or did you basically pull it all out and find bearings that fit?

I've never pull pedal/linage assembly so I am assuming its all just simple bushings, so you figured out bearings would be better.
a roller and heim type system only eliminates friction cause by the mechanical linkage so it will not make a huge difference in the amount of force required to depress the pedal.

yes the stock pedal support uses bushings.

heres the instruction info and the kit info for the pedal support conversion.

http://www.virginiaclassicmustang.com/howto/instructions/64-70ClutchPedalBearingInstr.pdf

https://www.cjponyparts.com/roller-bearing-clutch-and-brake-pedal-support-bushing-kit-1965-1970/p/HW1015/

SOME HEIM JOINT CONVERSION INFO

http://forums.vintage-mustang.com/general-discussion-non-vintage-mustang/533472-heim-joint-clutch-linkage.html

Zbar-001.jpg


 
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