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Street performance clutch types
https://www.slantsix.org/forum/viewtopic.php?t=64342		 Page 1 of 1
Author:  /6 Matt [ Thu Dec 26, 2019 3:10 pm ]
Post subject:  Street performance clutch types
Ok guys,

I've been through the performance clutch install thread and it looks like after almost 8 years and 12 pages the consensus is that our only good clutch option is to invest like $2k in parts.

But do I really need it? What kind of rpm is the stock flywheel good for? The car is a 1970 Dodge Dart, itll have a warmed over 225 with 3.73 gears and street tires. This will be a street performance car and it will see zero track time. I'd like to have the rev limiter set at 5k rpm and shift just shy of that. Could I just get away with having my flywheel redrilled for something better? What about a scatter shield or something?

Surely there has to be some sufficient options that dont cost more than the car?
Author:  DusterIdiot [ Thu Dec 26, 2019 5:01 pm ]
Post subject:  Re: Street performance clutch types
Quote:
What kind of rpm is the stock flywheel good for?
It's been good for 6200 rpm and high power clutch dumps...but the safety margin here is the clutch fizzles out before
the thing comes apart when using an aftermarket clutch that fits the 10" disc... the stock clutches won't last or will
explode pending size of B&B special. Hence the reason for the search for a better setup that is economical, but since the
engine doesn't share a small block bolt pattern we can't use clutch setups that will hold behind a 340 and are limited to
what will fit the stock bell, or hope a conversion and combination of parts will do the trick.
Quote:
Could I just get away with having my flywheel redrilled for something better?
Yes, there are other threads where people have had success with McCleod coming with a Ford disc and other brand pressure plate and having McCleod
redrill the flywheel.
Quote:
This will be a street performance car and it will see zero track time.
Doesn't matter, if you decide one day at the light you do a 6k clutch dump...it's no different than if you do it at the track...the big difference
will be if you pound the assembly up and down the gears under load say carving the curves...if the pressure plate fails to clamp, or the disc
can't shed the heat it will get mushy quick and you'll worry about cell coverage and a tow truck...
Quote:
What about a scatter shield or something?
That's added insurance for your feet if something comes apart.
Quote:
Surely there has to be some sufficient options that don't cost more than the car?
Kind of depends...$2000 clutch assembly and bell that is SFI rated, $3000 Dart, $5000 copay limit on insurance for ER surgery and prosthetics...???
Author:  Rick Covalt [ Thu Dec 26, 2019 5:45 pm ]
Post subject:  Re: Street performance clutch types
Or spend $4-500 on a SFI rated clutch and PP from Mcleod, have your flywheel redrilled and then wrap it in a transmission blanket. The pressure plate will be fine at those RPM's and the blanket is a fairly cheap piece of insurance. This may work at a lot less than $2000
Author:  /6 Matt [ Thu Jan 02, 2020 11:24 pm ]
Post subject:  Re: Street performance clutch types
Does anyone still sell the 10" clutch disc by itself? The mcleod piece is discontinued and all I can find are clutch kits.
Author:  Dart270 [ Fri Jan 03, 2020 3:46 am ]
Post subject:  Re: Street performance clutch types
I would absolutely use the stock flywheel for your application. Yes, I would spring for a McLeod clutch, if they still make anything for our flywheel. What are your engine buildup specs/components?

Lou
Author:  Greg Ondayko [ Fri Jan 03, 2020 6:44 am ]
Post subject:  Re: Street performance clutch types
Here are some options..

Look at the 4.0 Selections.

The Cover plate is the Same bolt pattern as mentioned in the article. Your flywheel would need to be re drilled.

The Disc is a 10" unit for all intents and purposes.
https://www.centerforce.com/products?ca ... rd=&mainc=

Additionally, Here:
https://www.rockauto.com/en/catalog/for ... disc,10605

Not sure on the quality or performance of any of these parts.

Yet some other resources:
https://www.falconauto.com/

https://www.southbendclutch.com/clutches/4604/


Greg
Author:  /6 Matt [ Fri Jan 03, 2020 3:49 pm ]
Post subject:  Re: Street performance clutch types
Quote:
Here are some options..

Look at the 4.0 Selections.

The Cover plate is the Same bolt pattern as mentioned in the article. Your flywheel would need to be re drilled.

The Disc is a 10" unit for all intents and purposes.
https://www.centerforce.com/products?ca ... rd=&mainc=

Additionally, Here:
https://www.rockauto.com/en/catalog/for ... disc,10605

Not sure on the quality or performance of any of these parts.

Yet some other resources:
https://www.falconauto.com/

https://www.southbendclutch.com/clutches/4604/


Greg
So the Ford disc also works? I was under the assumption that you use the Ford pressure Plate and the slant six 10" disc.

Thanks for the Links Greg
Author:  /6 Matt [ Fri Jan 03, 2020 3:53 pm ]
Post subject:  Re: Street performance clutch types
Quote:
I would absolutely use the stock flywheel for your application. Yes, I would spring for a McLeod clutch, if they still make anything for our flywheel. What are your engine buildup specs/components?

Lou
The build plan is listed here

http://www.slantsix.org/forum/viewtopic.php?f=19&t=62
Author:  Greg Ondayko [ Fri Jan 03, 2020 4:14 pm ]
Post subject:  Re: Street performance clutch types
My 10" 1 x23 spline disc is actually a ford unit.

Some say there is a slight difference between the pressure angles on the 1x23 mopar and ford splines... but I have 2 cars with this setup and no problems.


Greg
Author:  jcc [ Sat Jan 04, 2020 12:49 pm ]
Post subject:  Re: Street performance clutch types
Yes, I have also recently discovered the pressure angle issue, I'm in same boat, too late to turn back now. We'll see. :shock: :D
Author:  emsvitil [ Sat Jan 04, 2020 7:05 pm ]
Post subject:  Re: Street performance clutch types
Pressure angle?

Do you mean spline tooth shape?
Author:  GregCon [ Sun Jan 05, 2020 6:11 am ]
Post subject:  Re: Street performance clutch types
Basically, yes. The tooth spline shape (or profile) includes the 'pressure angle' which is the angle of the load bearing part of the tooth relative to the shaft centerline.

A Mopar 1-23 uses a 45 degree angle. I am not sure what a Ford uses (?) or if it is different (?) but if so I'd guess 30 degrees as those two seem to be the most common values used in the auto world. But, there are others. As you can imagine, a 45 degree is considered 'best' and the 30 degree is popular as it is less costly to produce.

If you run a mismatch...it'll probably work fine for a lower powered / lighter vehicle package. But at some point you'll reach the place where you start stripping teeth.

As a point of interest, I talked to a major aftermarket clutch maker a couple months back and asked 'what is the pressure angle for a Mopar 1-23 spline?' After some 'Let me check and get back to you' ....the answer was 'We don't know'. As it turns out, they buy their clutch hubs from 'outside' and simply order a batch of Mopar hubs...and no one takes it any further than that.

On pressure angles, from the Mark Williams site:

"You should also know that all splines are not the same and spools/differentials/axles with similar counts may not be 100% compatible. Mark Williams Enterprises utilizes what's known as a true involute spline design, which has a slight crown, and 45-degree pressure angle. An OEM Dana 60 has a 30-degree pressure angle. So even though both have 35 splines, they are not interchangeable. Some lesser quality axles have splines that are cut individually making it impossible to control the tooth profile and concentricity. All splines at Mark Williams are cut on a machine called a hob, which is the only way to create the true involute spline profile."
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