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Clutch- what have I done
#1
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
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#2
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.

'73 Grandé H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

'73 F code convertible. Bright red. Needs total restore. (IE HOT MESS)

- Jason
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#3
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
[+] 1 user Likes OzCoupe72's post
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#4
what disc are you using?

all mcleod and ask them what pressure the plate is.

Do you have the stock clutch linkage?
[+] 1 user Likes barnett468's post
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#5
(05-25-2018, 08:02 PM)OzCoupe72 Wrote: 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?
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#6
(05-25-2018, 08:55 PM)barnett468 Wrote: 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
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#7
(05-25-2018, 08:55 PM)barnett468 Wrote: 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
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#8
(05-26-2018, 09:36 AM)digithead Wrote:
(05-25-2018, 08:55 PM)barnett468 Wrote: 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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#9
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


When a man is in the woods and talks and no women are there is he still wrong??
Tongue
David
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#10
+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?



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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