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Long Arm or Diaphragm pressure plate?

October 8 2010 at 3:07 PM

  (Login N69MF)
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I'm putting a NV3550 Trans in my 69 Bronco and want to put a new pressure plate in to go with the resurfaced flywheel and clutch disk. The original pressure plate was a long arm style, but I see in Summit where both Long Arm and Diaphragm are available; don't have a clue which is better. Is there a difference or is one better than the other type?

Edit to add; the Bronco has a pretty much stock 302, plus headers, 4bbl 4100 and a little bigger cam.

Thanks!

Kerry


    
This message has been edited by N69MF on Oct 9, 2010 4:55 AM


 
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(Login Argess)
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Re: Long Arm or Diaphragm pressure plate?

October 8 2010, 3:23 PM 

I used a Mcleod Long style (3-finger) in mine and I'm having clutch chatter issues. However, it's most likely due to either an alignment issue, or condensation or oil disc contamination, not the design of the PP.

However, I did read this (don't shoot me.....I'm only cutting and pasting someone else's opnion):

Lever Style Pressure Plate
For several years, Ford used a pressure plate manufactured by Long in many of their vehicles from Mustangs to F series pickups. This pressure plate has 3 levers instead of a diaphram. The main problem with these units is that they have a tendency to chatter. A diaphram style pressure plate is available for these units. The covers are stiffer and the levers are eliminated. These replacement pressure plates are usually much smoother. If you can find one of these, use it rather than the lever type.

Comes from this link (close to the bottom of the page):http://www.clutch-shop.com/tips.htm


 
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Bobby Spears
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Re: Long Arm or Diaphragm pressure plate?

October 8 2010, 3:49 PM 

I found back in the days as a Ford tech ,that most long chatter problems were due to the discs springs,not the pressure plate.You just need a HD clutch kit and not worry about chatter.I have a long in my LWG and it doesn't chatter when moving around in the pits or loading it in the trailer,of course on launch at the track it doesn't have a chance to chatter when you pop the clutch pedal at 5000 or so,lol.

[linked image]

 
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(Login MT63AFX)
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I don't know, diaphragm clutches are like HEI distributors, they belong in.........

October 8 2010, 5:46 PM 

......GMs. Don't use a Long-style from a hydraulic 352/390 in a beefed up 427/8, it will probably chatter. Bobby and I, as well as others, have not had any issues with an OE 427 clutch ass'y back in the day. There were 'tricks' to do to the 427 PP's arms to assure disengagement at 6,500rpm-7,000rpm everytime, all the time. I have the Hayes/Scheiffer set-up now and bought it when they were rated basicly by vehicle weight, "yeah, it's gotta 3,500lb clutch", LOL, JMO, Rod.

Mickey Thompson's 63 1/2 #997 S/S Hi-Rise 427 Lgt/Wgt Galaxie,
1957 C-600 Cab-over carhauler w/390-4V, 2-speed rear-end
FGCofA member #4908
MCGC member #75

"There will ALWAYS be an FE in my LiFE"

 
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(Login N69MF)
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No Clutch kit available for this application

October 9 2010, 5:04 AM 

Because of the NV3550 trans, there's no kit for this; the clutch disk is different from the original; it's 11" compared to the stock 10 1/2" and the spline count is also different. Same for the pilot bushing; they sent me a stock bushing that had been milled out a bit to fit the NV3550.

I assume the stock pressure plates are for 10 1/2" disks. When I put the new disk on the old pressure plate, there's less than 1/8" of disk showing and it clears everything, so I'm thinking the stock plate would be OK. Summit has 11" plates but they cost around $200.00+ where a stock plate is $50-80.00.

Kerry

 
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Brent Lykins, B2 Motorsports
(Login blykins)
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I can get whatever you want Kerry.....Long or Diaphragm...

October 9 2010, 5:06 AM 

If you have trouble finding what you want, just let me know.

Photobucket

 
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(Login N69MF)
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The problem is that I don't know what I want ~

October 9 2010, 5:11 AM 

LOL! Just want the best plate for this application and was a bit confused about the whole thing.

Because it's a conversion, the disk is not the same as a stock disk, it's 11" instead of 10 1/2" and the spline count is different, so there's no "Clutch Kit" for it.

Kerry

 
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(Login MT63AFX)
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Don't be surprised for the lack of an available kit. The disc's parameters.........

October 9 2010, 6:00 AM 

...........just need to match the spline and PP diameter, the PP matches to the flywheel's bolt patterns. If this for a heavy vehicle, I'd get the Long, if it's for a Ford, I'd get the Long. Did I mention I prefer the Long? LOL, JMO, Rod.

Mickey Thompson's 63 1/2 #997 S/S Hi-Rise 427 Lgt/Wgt Galaxie,
1957 C-600 Cab-over carhauler w/390-4V, 2-speed rear-end
FGCofA member #4908
MCGC member #75

"There will ALWAYS be an FE in my LiFE"

 
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Wes Adams Ford428CJ
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I have ran both & I do a Long Throw in a 4X4~

October 8 2010, 9:02 PM 

I ran 3 finger for years with no ill effect with a wormed over solid roller 428. I did a diaphragm and it didn't hold up to the power/35" tires/ 3.50 gears. To much for it. JMHO

"The Poor Mans 427"
http://www.fordification.com/poormans427.htm

"The F.E. Wiki Home"
http://fordfe.wetpaint.com/

[linked image]
Wes Adams FORD428CJ
Built Ford Tuff With Good Ford Stuff
03 F-250 Crew Cab 4x4 6.0 and 35's
64 Falcon 428FE
55 FORD Truck 4-link Rides on air with 428FE
2000 Yamaha V-MAX VMOA#4277
2000 Yamaha 700 Mountain Max
2001 Polaris 600 Edge X
2001 Polaris 500 SP

 
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(Login Argess)
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My Long PP is a low pressure unit

October 9 2010, 4:29 AM 

I just checked the Mcleod website and my Long style PP is only rated at 1700 lbs clamping force.....of course it's only a 2500 lb car.

 
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Brent Lykins, B2 Motorsports
(Login blykins)
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The pressure plate and disc work together....

October 9 2010, 4:57 AM 

...they're really not rated in "weight of car". What you're seeing is the static clamping force of the pressure plate.

In a clutch system, you of course have a pressure plate and disc. You mix and match each one to get the results you want. If you want a clutch that grabs more, you can either increase the static pressure of the pressure plate, or you can increase the friction coefficient of the disc. If you want less pedal effort, but want to hold more horsepower, then you have to step up to a disc with a high coefficient of friction. On the converse, if you want to hold a lot of horsepower, but you don't want to deal with clutch chatter and instant engagement, then you can use a low friction disc and a high clamping force pressure plate.

You have to look at both the pressure plate and clutch disc as a whole package. Just because a diaphragm plate doesn't hold doesn't mean that the plate was weak...you have to look at what disc you're using as well.


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Barry R
(Login Barry_R)
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Long style

October 9 2010, 4:57 AM 

is the better choice for about 90% or more of these cars. The only real advantage of the diaphram is lighter pedal pressure - pretty much a "who cares" item more appropriate to the days when they were helping out ladies driving economy Chevettes to the local grocery.

We sell the McLeod long style kits frequently and never here a complaint about the pedal pressure. Chatter issues encountered by Ford forty years ago probably do not apply to modern performance parts.

Barry Rabotnick
Survivalmotorsports.com

 
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Brent Lykins, B2 Motorsports
(Login blykins)
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Just depends on what disc you use...

October 9 2010, 5:04 AM 

As an extreme example, a 4000 lb car with a 2.73 rearend, using a 500/600/800 series McLeod disc will probably get some chatter. Also, a Kevlar disc is more likely to chatter under heat than a sintered bronze (McLeod 500 series). On the same token, the same car with a RAM Powergrip or Powergrip HD will probably get some chatter, just due to their discs being made with sintered iron pads.

Of course when your engine is producing 550 hp (and up), you really have to compromise on what kind of street manners you may get.

I really don't get any complaints of chatter either with the McLeod or RAM stuff and I sell a ton of each. However, most of my customers don't drive 4000 lb cars with 2.73 rearends. happy.gif

As a whole, I would warn everyone to stay away from the Spec clutches along with some other brands. The Spec stage 3 clutch has a non-sprung paddle disc and it will absolutely drive you nuts with chatter and instant engagement.

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(Login N69MF)
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The conversion kit came with a disk ~

October 9 2010, 5:09 AM 

It's a Centerforce disk, part # 383735. Since it didn't come with a plate, I'm thinking they assumed I would reuse the old plate, but I really don't want to put the old one back in and would rather put the best plate for the application.

Kerry

 
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Brent Lykins, B2 Motorsports
(Login blykins)
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You'll more than likely need a Centerforce plate then...

October 9 2010, 5:21 AM 

...if I remember correctly, C/F uses a proprietary thickness on their discs, and other brands of pressure plates may/may not work.

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(Login Bad427stang)
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Both work great nowadays

October 9 2010, 6:53 AM 

The Long is easier to use in a vehicle that originally used a long because you don't have to pull the assist spring from the pedal and the linkage throw is designed for a Long. I run a Ram from their Musclecar line in my 70 4x4 and it works great.

I like aftermarket diaphragm plates because of pedal pressure and they are usually a little lighter, but if you have too much pedal throw, which you might with the stock Bronco setup, it can overcenter and drag a little, at that point you have to make up some sort of stop, and you may have to pull the assist spring. I run a McLeod diaphragm in the Mustang and LOVE it, I eliminated the helper spring but use stock linkage modified with Heim joints. Its smooth like a new car.

The big benefit is that the diaphragm is real easy on your leg, and despite not sounding like a huge deal, it is a big deal if in traffic or jockeying around off road. I also ran this car with a big crazy Long style for years and didnt complain, but I like this one WAY better.

You can't go wrong with either, but like Brent eluded to, the grip of a clutch is a combination of clutch material and clamping force, so you really want to try to use things that make sense together.

I am not a big Centerforce fan but they do work, so if the Centerforce disk thickness is true, I'd either toss the CF disk and buy nice McLeod or Ram pressure plate and disk that go together with the spline and size you need (Brent can get you there) or buy a Centerforce Long or Diaphragm based on what I described.

You cant really go wrong, light truck, small motor, good gear ratios won't be fussy......happy vs glad happy.gif



[linked image]
---------------------------------
- 70 Fastback Mustang, 489 cid FE, EFI, TKO-600 5 speed, 3.70 9 inch.
- 71 F100 shortbed 4x4, 397 cid FE, headers, Street Dominator, 280H, 4 speed

 
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(Select Login ford428cj)
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Not to disagree but~

October 9 2010, 8:05 AM 

When you have the leg room.... Doesnt really matter too much then. Being in a car is a little tough on the left leg then. JMHO

"The Poor Mans 427"
http://www.fordification.com/poormans427.htm

"The F.E. Wiki Home"
http://fordfe.wetpaint.com/

[linked image]
Wes Adams FORD428CJ
Built Ford Tuff With Good Ford Stuff
03 F-250 Crew Cab 4x4 6.0 and 35's
64 Falcon 428FE
55 FORD Truck 4-link Rides on air with 428FE
2000 Yamaha V-MAX VMOA#4277
2000 Yamaha 700 Mountain Max
2001 Polaris 600 Edge X
2001 Polaris 500 SP

 
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(Login Bad427stang)
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You'll get old someday too Wes

October 9 2010, 8:21 AM 

but I do agree, my truck has a lot more leverage and a better angle than the car (and it does have a Long PP too)

[linked image]
---------------------------------
- 70 Fastback Mustang, 489 cid FE, EFI, TKO-600 5 speed, 3.70 9 inch.
- 71 F100 shortbed 4x4, 397 cid FE, headers, Street Dominator, 280H, 4 speed

 
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(Login bbr60)
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When you get really old you get an automatic

October 9 2010, 10:13 AM 

because with P.A.D. your legs and feet are numb along with your cognitive processes.

 
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(Login Bad427stang)
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LOL my daily driver is an AT Powerstroke

October 9 2010, 10:25 AM 

I sure love it, especially with a coffee in the cup holder LOL

[linked image]
---------------------------------
- 70 Fastback Mustang, 489 cid FE, EFI, TKO-600 5 speed, 3.70 9 inch.
- 71 F100 shortbed 4x4, 397 cid FE, headers, Street Dominator, 280H, 4 speed

 
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Wes Adams Ford428CJ
(Select Login ford428cj)
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LMAO.... A Power Stroke is my DD too!~

October 9 2010, 8:00 PM 

And I'm BIG on coffee! LOL

"The Poor Mans 427"
http://www.fordification.com/poormans427.htm

"The F.E. Wiki Home"
http://fordfe.wetpaint.com/

[linked image]
Wes Adams FORD428CJ
Built Ford Tuff With Good Ford Stuff
03 F-250 Crew Cab 4x4 6.0 and 35's
64 Falcon 428FE
55 FORD Truck 4-link Rides on air with 428FE
2000 Yamaha V-MAX VMOA#4277
2000 Yamaha 700 Mountain Max
2001 Polaris 600 Edge X
2001 Polaris 500 SP

 
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