Author Topic: Clutch problems  (Read 628 times)

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BigBlueIron

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Clutch problems
« on: July 11, 2018, 10:13:12 AM »
Well I have a problem, clutch slipped on me last night during some "testing" so I guess that's a good problem right??  :)

 I rolled hard in the throttle at about 50mph and it let go probably around 70 or so. In 4th gear so 1:1 with 4.27 rear gear. If anyone wondered.

Current clutch stocker 3 finger, 11" if memory serves, fresh grind on the flywheel. Works and feels great, nothing wrong at all with it just couldn't hang on. What is the capacity of a stock type clutch? Or what kind of power does it take to blow through one while at speed? No idea what this engine makes power wise, be nice to have a half assed idea.

When the time comes to change it I plan on doing an SFI flywheel, I'm guessing it will be simpler to buy all at once anyway. McLeod?? Ive heard Centerforce is junk. Only performance type clutches Ive dealt with are multi disk slippers and company's that specialize in those.

blykins

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Re: Clutch problems
« Reply #1 on: July 11, 2018, 10:23:30 AM »
350-400 hp is what the stock style replacements are good for.

You're good in selecting a McLeod or RAM for your next go-round.

Once you make it slip, it will start slipping more and more.
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BigBlueIron

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Re: Clutch problems
« Reply #2 on: July 11, 2018, 10:37:53 AM »
I forgot to mention that the current pressure plate has the counter weighted fingers.

Thanks for the recommendation,

Yep, but just plan to drive it for awhile. Just got it on the road recently so I'll just lay off the boost some.

BattlestarGalactic

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Re: Clutch problems
« Reply #3 on: July 11, 2018, 10:49:46 AM »
so I'll just lay off the boost some.

Yup, there's the problem...... ;D

How much boost?

BigBlueIron

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Re: Clutch problems
« Reply #4 on: July 11, 2018, 11:25:09 AM »

Yup, there's the problem...... ;D

How much boost?
[/quote]

More than safe, smart or sustainable, by a lot..  Its a 30 pound gauge and will use all of it if you want it to...

blykins

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Re: Clutch problems
« Reply #5 on: July 11, 2018, 11:33:33 AM »

Yup, there's the problem...... ;D

How much boost?

More than safe, smart or sustainable, by a lot..  Its a 30 pound gauge and will use all of it if you want it to...
[/quote]

Well poop the bed.

You have a twin disc in your future.
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BigBlueIron

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Re: Clutch problems
« Reply #6 on: July 11, 2018, 11:52:50 AM »

Yup, there's the problem...... ;D

How much boost?

More than safe, smart or sustainable, by a lot..  Its a 30 pound gauge and will use all of it if you want it to...

Well poop the bed.

You have a twin disc in your future.
[/quote]

lol No, it will be limited around 15.

Question Brent, Could I just swap the friction for say the RAM 300/900 disc? I always thought the counter weighted long style pressure plate I have was a good unit.

BTW anyone have a good used SFI flywheel for sale?

blykins

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Re: Clutch problems
« Reply #7 on: July 11, 2018, 11:57:50 AM »
Depends on which pressure plate it is.  Some disc manufacturers use a proprietary disc thickness and the air gap won't be right with different pressure plates.

A 900/300 RAM disc would be rated for 550 hp with the correct pressure plate.

Another note to make is that individual component pricing is unreal compared to kit pricing.  The price of a clutch disc by itself would be way over half the price of a complete kit and you'll probably find that your pressure plate has been a little hot anyway.
Brent Lykins
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BattlestarGalactic

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Re: Clutch problems
« Reply #8 on: July 11, 2018, 12:15:08 PM »
At what RPM is 70 mph?   Those CW levers are fine, but if you aren't high enough on rpm then they will not give full clamping capacity.  Thus it is harder with a boosted vehicle to run a clutch(at least a soft one).  They have to be aggressive because they have to hold at low rpm/high boost.

The dual disc unit just doubles up the surface area, effectively giving you more clamping force with less base pressure then a single disc.

fekbmax

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Re: Clutch problems
« Reply #9 on: July 11, 2018, 12:54:17 PM »
What's the base pressure ? Have you added any counter weight ? What type of disk ? If it's a counter weight then i think it most likely would have adjustable base.
Keith.  KB MAX Racing.

BigBlueIron

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Re: Clutch problems
« Reply #10 on: July 11, 2018, 12:58:53 PM »
Depends on which pressure plate it is.  Some disc manufacturers use a proprietary disc thickness and the air gap won't be right with different pressure plates.

A 900/300 RAM disc would be rated for 550 hp with the correct pressure plate.

Another note to make is that individual component pricing is unreal compared to kit pricing.  The price of a clutch disc by itself would be way over half the price of a complete kit and you'll probably find that your pressure plate has been a little hot anyway.

Not worth messing with, pull it out before I ruin it and save it for a stock pickup. Brent Ill shoot you an email.

At what RPM is 70 mph?   Those CW levers are fine, but if you aren't high enough on rpm then they will not give full clamping capacity.  Thus it is harder with a boosted vehicle to run a clutch(at least a soft one).  They have to be aggressive because they have to hold at low rpm/high boost.

The dual disc unit just doubles up the surface area, effectively giving you more clamping force with less base pressure then a single disc.

Well I did some quick math with my set up and that would be 3350rpm at 70 I think my mph is off. I was just guessing as I have no speedo just a tach, which is all I need anyway, but it was pulling like a freight train and looking at the tach wasn't on my mind lol.

You know you guys make a point on the dual disc. Since I really need it all anyway how much would it cost? Probably not much. Plus a street type dual disk might be more street friendly. Just a guess though.

What's the base pressure ? Have you added any counter weight ? What type of disk ? If it's a counter weight then i think it most likely would have adjustable base.
No idea on base pressure nor is it adjustable. Organic disc nothing special. It is the fixed weight, only good way to add weight to them is weld them up.

blykins

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Re: Clutch problems
« Reply #11 on: July 11, 2018, 01:05:14 PM »
What trans?
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BattlestarGalactic

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Re: Clutch problems
« Reply #12 on: July 11, 2018, 01:29:51 PM »
What's the base pressure ? Have you added any counter weight ? What type of disk ? If it's a counter weight then i think it most likely would have adjustable base.

Lots of stock pressure plates have CW hanging on the levers(I've used them many years back), but none are adjustable base pressure.  Only aftermarket, racing clutches have adjustable base pressures.


Well I did some quick math with my set up and that would be 3350rpm at 70 I think my mph is off. I was just guessing as I have no speedo just a tach, which is all I need anyway, but it was pulling like a freight train and looking at the tach wasn't on my mind lol.


Ya, at 3400 rpm, I'm pretty sure that CW is no where near full potential.  Like I mentioned, a dual disc will get you the surface area(without insane pressure=heavy clutch pedal) needed to support that kind of power at low rpm.  If not, you will have to get a pretty stiff stock single pressure plate to hold the same power.

fekbmax

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Re: Clutch problems
« Reply #13 on: July 11, 2018, 01:55:00 PM »
Yeah, my bad. I miss understood. Thought it had adjustable CW, not fixed. Was wondering how that coulda been a stick PP.
Keith.  KB MAX Racing.

BigBlueIron

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Re: Clutch problems
« Reply #14 on: July 11, 2018, 04:22:10 PM »
What trans?

Which one? Its got 2! lol Advance Adapters Road Ranger in front of an NP435. As far as the clutch is concerned its the same as a stock setup with a 435. Shifts like crap but that's probably a good thing, If I would have went C6 I'm sure I would have wrecked it by now.

blykins

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Re: Clutch problems
« Reply #15 on: July 12, 2018, 04:58:24 AM »
What trans?

Which one? Its got 2! lol Advance Adapters Road Ranger in front of an NP435. As far as the clutch is concerned its the same as a stock setup with a 435. Shifts like crap but that's probably a good thing, If I would have went C6 I'm sure I would have wrecked it by now.

1-1/16x10? 

How much power do you think you're making?  Car/truck?  Rearend ratio?  Tire size?
Brent Lykins
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BigBlueIron

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Re: Clutch problems
« Reply #16 on: July 12, 2018, 09:21:53 AM »
What trans?

Which one? Its got 2! lol Advance Adapters Road Ranger in front of an NP435. As far as the clutch is concerned its the same as a stock setup with a 435. Shifts like crap but that's probably a good thing, If I would have went C6 I'm sure I would have wrecked it by now.

1-1/16x10?  Yep

How much power do you think you're making?  Car/truck?  Rearend ratio?  Tire size? 1950 F1,  4.27 rear. Will probably stay around this, maybe 4.10 in the future.   31" tire.

blykins

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Re: Clutch problems
« Reply #17 on: July 12, 2018, 09:27:35 AM »
The tall tire counters the deeper rear gears quite a bit.

How much power do you think you're making?
Brent Lykins
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BigBlueIron

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Re: Clutch problems
« Reply #18 on: July 12, 2018, 11:04:56 AM »
I really don't know. I have plans to put it on the chassis dyno when I get some things ironed out. Mostly for tuning and see what it makes for fun. But that would now be a waste of time on a clutch that can't hold it.

Engine I believe is stock well used truck 390 D2 heads, with addition of a Streetmaster intake. So whats that 210hp? Really didn't expect it to run as well as it does.

So using http://www.wallaceracing.com/hp-blower.php a rough guess would be 425 @ 15psi or 640 @ 30psi.

I do have a small cam that might go in .495 lift 220 @ .5, 276 adv 113 separation.

BattlestarGalactic

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Re: Clutch problems
« Reply #19 on: July 12, 2018, 01:02:29 PM »
My 390 is a stock rebuilt 68 2bbl car motor(org cast pistons), with 5# of boost.  Does have a .53 lift flat tappet(not a blower cam--just what I had laying around).  With 600 holleys it pulled 111 mph in the 1/4, though ET is ridiculously slow at 14.0 since it blazes the tires for 3 gears on BFG radial T/A's.  I run a dual friction disc on a Ram adj plate(spare pieces from race car).  I think the plate is 2200#?  Give or take.  I bought it on the junk table at Summit a few years back.

I've wanted to turn the boost to 10#, but don't want to scatter those vintage stock cast pistons and stock bore block.

As a note, when the motor did not have the blower, it was a complete dog.  I mean slllloooowwwww.  Took all it's effort to bark the tires between gears.  5# of boost really woke it up.  Using Wallace calculators I should be about 450 hp(running 111 mph) which equates to low 12's.

https://www.youtube.com/watch?v=Lai12DsFzW0

BigBlueIron

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Re: Clutch problems
« Reply #20 on: July 12, 2018, 02:11:34 PM »
Amazing car!

I have no expectation of this current engine staying how it is, I consider it an interim until time and money allow me to use a few of the parts I have laying around that will handle a boosted app much safer.  But I want to build everywhere else as if it was more powerful than it is. Because it will be and I hate buying parts twice. You know, bye a clutch just to bye a bigger one later scenario.

I never really drove this truck without the turbos so not sure how it would be without them. But its nothing to write home about until the boost gauge comes up to around 5lbs then things really start to happen. This a thrown together turbo setup and I'm happy at how driveable it is so far. I wish the boost came in stronger at low RPM but that's just because I'm to used to diesel. A blower like yours would fix that tho! Comparing to other turbo setups I think it responds well, and I can tweak that some too.

The cam I mentioned was a custom regrind (Oregon Cams) of my own thoughts with boost and propane in mind.  Tried to minimize overlap and keep a stock valvetrain unstressed. Like a weird RV cam lol It will end up in this truck sooner or later.

So would you say the Wallace calculator is close in your application?

BattlestarGalactic

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Re: Clutch problems
« Reply #21 on: July 12, 2018, 02:26:45 PM »
I was going to put good parts in this, but back in 2000 I lost the motor in the wagon and everything I was going to spend on this went towards the wagon.  Thus it is all stock, but fresh.  Fully prepped, blueprinted and such, but stock with new rod bolts and the cam I had running stock adj rockers..  It likely has too much overlap for a blower, but, it works.  I'd like to get a 445 kit for it and turn the wick up.  Oh, someday, when I have the "extra" money=never.

I used to have an old race clutch in it, sintered iron.  It was brutal to drive as it was really chattery.   I finally wore it out and like I said, had the PP and used it with a new DF disc.  A bit easier to drive, bit heavier pedal, but not as chattery.

It started with 600's off my pickup motor(428), then I found a pair of 660's.  I went through them but still have not got them tuned perfect.  Need to work out a bad mid range bog.  That big alum box takes a lot of fuel to keep happy.  I don't beat on it much, as I don't want to hurt it.  It's a cruiser for the most part.  Only took me 18 yrs to finally put a Unilite conversion in the stock distributor with an MSD.   Starts easier, runs better now the points don't jump.

I've contemplated a twin turbo on my '69 F100.  Kinda sneaky and would be a blast to drive.  The black car is a PITA with that huge barn in your vision 24/7.  I could make up a set of shorty headers turned upside down and mount the turbos over them and plumb them into each carb.    Ya, sounds like a tuning nightmare  :o

As for Wallace numbers?  Hard to say how accurate.  I only go by the MPH basically.  I know the wagon made 550 hp back when and ran 116~ mph at mid 11's.  Now it makes 625(dyno) and goes 123 mph(good day), 120(warm day) at 10.9.
« Last Edit: July 12, 2018, 02:30:14 PM by BattlestarGalactic »

Heo

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Re: Clutch problems
« Reply #22 on: July 12, 2018, 04:01:49 PM »
Beautiful In Black

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