Violent Take-Off Shudder

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FI and race cars use some exotic brake pads and it takes laps of heat to get them to where they work right. Wonder of Ceramic is the ideal choice for a clutch in a street car? Brewers will sell you anything they think will work, did you tell them this was a street car? Also the Super stock springs are like 2" taller than stock and you still list a factory snubber, ie factory ride height snubber..ie its way too short to work. I have an adjustable snubber for you.
 
dkbug said:
I'm not going to doubt you as you definitely have more experience than me, and you are likely correct because of said experience. However, I am going to ask for you to elaborate on your thought about why the fact that eliminating axle wrap essentially eliminates my original complaint isn't the source, but the clutch is. I am a mechanical engineer by trade, so please excuse my questions. I genuinely would like to understand the thought process.

Sitting in idle, the clutch is very quiet. Shifting into any other gear is perfect and quiet. Reverse is perfect and quiet. Its only when taking off in first gear that I am seeing the majority of the action happening at my rear diff. The clutch only has 800 miles on it by the way. Its not gotten any worse/better. When I put that 3" worth of wood above the snubber, ALL shudder disappeared.
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I’ll ask you. What made the axle wrap up?? Your clutch is violently beating the crap out of the rear end. All you are doing is putting a band aid where you need a tourniquet.

You want to control axle wrap with some boards or a pinion snubber. All that does is stop the symptom. The disease roll merrily along.
 
pishta said:
FI and race cars use some exotic brake pads and it takes laps of heat to get them to where they work right. Wonder of Ceramic is the ideal choice for a clutch in a street car? Brewers will sell you anything they think will work, did you tell them this was a street car? Also the Super stock springs are like 2" taller than stock and you still list a factory snubber, ie factory ride height snubber..ie its way too short to work. I have an adjustable snubber for you.
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Ceramic isn’t a good choice for a clutch disc in most any car. It’s way to violent. And it doesn’t like getting slipped. It’s like driving a toggle switch. It’s either in or out, on or off. Get in a place where you need to be able to manipulate the clutch it shakes it’s brains out.
 
What is so hard about dropping out the 4spd, unbolting the bell housing reaching up with swivel sockets and long extensions.

Then remove the clutch and swap it out with a factory pressure plate and stock clutch disc.

4 hr job at max, easy peasy.

Problem solved.

Screenshot_20210518-080603_Chrome.jpg


Then ship back the Brewer clutch assembly and get a refund on the parts. Covers the cost of the new factory clutch from Rock.
 
I really think you should change the clutch out, like I said in my post above I had the exact same problem and the second I put car into first I knew immediately it was fixed.
 
George Jets said:
What is so hard about dropping out the 4spd, unbolting the bell housing reaching up with swivel sockets and long extensions.

Then remove the clutch and swap it out with a factory pressure plate and stock clutch disc.

4 hr job at max, easy peasy.

Problem solved.

View attachment 1715739295

Then ship back the Brewer clutch assembly and get a refund on the parts. Covers the cost of the new factory clutch from Rock.
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Its a big block car with 2" TTI headers.... Nothing is a 4 hour job....

If I swap the clutch out, I need one to hold 600+ HP. That perfection clutch will be toast in 1000 miles. Any other suggestions of clutches for high hp applications?
 
Here is Summit Racing's "All About Clutches" Video for high performance clutch selection for your particular setup.
(They start talking about Clutch Disc Selection at 4:45 minutes in on the video.)





You will want to be looking at a pressure plate that works within your horse power range for driving on the street . . .

Then select the clutch disc type: Sprung or Unsprung, and the Clutch Disc material for your driving habbits.

Putting your selections together, you can compare the stock pressure plate pressures to the performance clutch pressure plate pressures to help guide you in your decisions.

Good Luck with your build up. Lots of suppliers online and on ebay once you know the components you are looking for.
 
dkbug said:
Its a big block car with 2" TTI headers.... Nothing is a 4 hour job....

If I swap the clutch out, I need one to hold 600+ HP. That perfection clutch will be toast in 1000 miles. Any other suggestions of clutches for high hp applications?
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Ok, now I see your mistake. You are buy a clutch based on horsepower. That’s not the way to do it. All those “high horsepower” clutches are nothing but violent parts breakers.

Here’s what I’d do. My advice is worth exactly what your paying for it.

I’d go back to a Borg & Beck cover. I would use the McLeod heavy duty rag (organic) disc without the marcel spring. I would take the cover to a local shop that does frictions and such and have them set the spring pressure at 2400-2600 pounds and use no roller assist and send it.

You may be able to buy a cover that’s already at that plate load. I’m not sure on that, because I can’t find my McLeod catalog.

If you are going to beat on the car with slicks then you have to either buy a different clutch (what I’d do) or buy a Clutch Tamer. The clutch I’d run if you’re going to beat on it is a McLeod Sof-Lok but that clutch was 2200 bucks last time I looked. You can get a similar set up from Advanced Clutches or Black Magic Clutches.

If you are just street driving all you need is the first clutch.

Don’t get caught up in horsepower and clutches. It’s a parts breaking disaster.
 
Do you now have a Double Disc Clutch assembly from Brewer's?

Single Disc Clutch Assembly?

Clutch Disc Type, Sprung or Unsprung?
And Clutch Disc Material? (sounds like you have Ceramic both Sides???)

mcleod-rst-street-twin-clutch-kit-72.gif


singleDisc.jpeg


SingleSprungDisc.jpeg




1 2.png





This has been a little over-answered. Unsprung clutches are not at all uncommon in clutch kits for conventional upgrade paths.
The main difference is they grab much more abruptly. Especially if you have ceramic pucks. And they rattle on deccel.

(An upgraded clutch can ruin your experience altogether.) Choose Wisely
 
I seem to recall pulling the gearbox back, and unbolting the pressure plate one bolt at a tine, with the bell still bolted up, and dropping the disc out the bottom..or was I dreaming? I cant remember why I would have done it that way but yes, small block 4 speed I can have out in an hour...or should I say "in my youngrer days...":) My issue ended up being a bad pressure plate, one of the balancing weights flew off at some point or it was defective when new. But I could run it a 2000rpm in neutral and it would shake and vibrate terribly. The point is to the OP "you will get good at pulling the transmission quickly" chasing down this one...
 
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Dartswinger70 said:
I seem to recall pulling the gearbox back, nad unboltong the pressure plate one bolt at a tine, with the bell still bolted up, and dropping the disc out the bottom..or was I dreaming? I cant remember why I would have done it that way but yes, small block 4 speed I can have out in an hour...or should I say "in my youngrer days...":)
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Yes ^^^^^ I like this thinking. Drop the clutch out the bottom of the bell housing, if your removed inspection cover area gives you the clearance to do so.

Looks like that will easily drop out the bottom of the bell housing, with the bell still bolted up.

BBBell.jpg
 
dkbug said:
I am assuming you still need to yank the starter?
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No you shouln't have to pull the starter. . The clutch and pressure plate will come out the bottom, then you'll have to hold the new one up in there get the alignment tool started, and then start the pressure plate bolts one at a time, rotate the engine around to get the pressure plate bolts in, and once they are all in go around the pressure plate snugging them down evenly this will require you turn the engine either with a pry bar on the flywheel teeth or with a ratchet on the crank damper bolt of the engine. But don't run the pressure plate bolts down tight one at a time work around in a star pattern making sure the clutch disc stays centered with the alignment tool. it sounds like alot of screwing around, but if it saves the aggravation of the starter and bell coming out it may work for you. Most times you may be able to pull the gearbox "back" and leave it "up there" on a jack and you wont have top drop exhaust either. You just have to clear the pressure plate with the input shaft to drop it out the bottom.
 
ok, change the disc. mcloed series 300 disc will be your best bet. A B&B pressure plate at 2200 to 2400, will make it work good, I run a stick shift 340 stocker, I've ran that style clutch before, now I have a soft loc style, have the pressure plate checked for warp. it's probable warped bad. same with flywheel, I've ran clutch cars for over 50 years.
 
perfacar said:
ok, change the disc. mcloed series 300 disc will be your best bet. A B&B pressure plate at 2200 to 2400, will make it work good, I run a stick shift 340 stocker, I've ran that style clutch before, now I have a soft loc style, have the pressure plate checked for warp. it's probable warped bad. same with flywheel, I've ran clutch cars for over 50 years.
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Right now I have a Mcleod M360700 Pressure plate at 2750# and a M260620 double ceramic single sprung disc.
 
perfacar said:
ok, change the disc. mcloed series 300 disc will be your best bet. A B&B pressure plate at 2200 to 2400, will make it work good, I run a stick shift 340 stocker, I've ran that style clutch before, now I have a soft loc style, have the pressure plate checked for warp. it's probable warped bad. same with flywheel, I've ran clutch cars for over 50 years.
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Thank’s perfacar, I couldn’t think of that series of disc and I STILL cant find my catalog to look it up.
 
dkbug said:
Right now I have a Mcleod M360700 Pressure plate at 2750# and a M260620 double ceramic single sprung disc.
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I don’t know if there is a way to drop the pressure on that style of pressure plate but there may be. Since you already have it, if you can get the pressure down that would save some money. Then just replace the disc with the disc perfacar said above and you should be golden.

Public disclosure for truth. Just so you know, I personally detest the diaphragm pressure plate. I don’t think it’s as good a piece as the standard Borg & Beck plate, and the best plate is the Ford Long piece.

Unfortunately for us Chrysler guys, you can’t fit an 11 Long cover on our 130 tooth flywheels. You can now buy a nice 10.5 inch Long cover but it ain’t cheap. You can still find a few guys (Black Magic Clutches for one) who can make up a Borg & Beck/Long cover that will fit your flywheel and you can get the benefit of the Long fingers and still bolt it to a 130T flywheel.

All of that is way more than you need. Less plate load and that disc mentioned above is what you need. I posted the rest of this stuff for educational purposes, so maybe someone coming along later will read this thread and not buy a clutch based on horsepower and not buy a violent, parts breaking clutch. BTDT, as I am a slow learner.

A smooth, controlled application of the clutch will be quicker, faster and drive better than a nasty, pissed off violent clutch.
 
dkbug said:
I am assuming you still need to yank the starter?
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No, bell housing, starter and Flywheel stays on the car.

Just remove the pressure plate one bolt at a time then rotate by hand to the next bolts until you get all the pressure plate bolts out.

Then drop the pressure plate and clutch disc out the bottom.

Reverse proceedure for reassembly. Can reach in through the trans input shaft hole in the bell housing to use your clutch spline line up tool so you get your clutch disc on center with the pilot bearing.

Then evenly snug all the pressure plate bolts till tight. Then poke your 4 spd trans back in.

As the guys are talking above ^^^^^.

8W5A3912a.jpg


Clutch line up tool inside your bell housing.
 
Problem solved.... drive line angles were all jacked. Engine centerline and drive shaft had a 0 degree difference while the diff was 4 degrees down from the drive shaft.

Shimmed the trans up about 5/8" and shudder is gone. Good thing I didn't yank the clutch.
 
dkbug said:
Problem solved.... drive line angles were all jacked. Engine centerline and drive shaft had a 0 degree difference while the diff was 4 degrees down from the drive shaft.

Shimmed the trans up about 5/8" and shudder is gone. Good thing I didn't yank the clutch.
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So was this a new install or just a clutch change, because 5/8 is a HUGE move.
 
You were 2.4* pinion nose down to the drive shaft. The MP suspension book says 5-7. No wonder is was shaking. Also of note, with the SS springs, the rear segments of the springs are not "supposed" to be wrapped. Only the front segments.
 
Not sure that was the right fix, just masking the symtoms with the trans angle change.

20210519_070146.jpg


Bad driveline angles would have shook in all gears at all speeds.

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Clutch is NOT the problem. Driveshaft angles matter...especially when you get into a more aggressive clutch. Putting a rag disc back in the car with 550+ hp would have masked the problem...and resulted in the need to pull the trans once again. The OP and I worked through the problem....and got it right....problem solved.
 
dkbug said:
Problem solved.... drive line angles were all jacked. Engine centerline and drive shaft had a 0 degree difference while the diff was 4 degrees down from the drive shaft.

Shimmed the trans up about 5/8" and shudder is gone. Good thing I didn't yank the clutch.
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Sometimes it is a process of elimination. Good to hear you figured it out.
 
RustyRatRod said:
You were 2.4* pinion nose down to the drive shaft. The MP suspension book says 5-7. No wonder is was shaking. Also of note, with the SS springs, the rear segments of the springs are not "supposed" to be wrapped. Only the front segments.
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This is correct Rusty. I will add to this. Though the spec is 5-7, this wouldn't have made much of a difference until I put my foot in it. That 5-7 degrees is for the allowance of axle wrap to avoid trashing your ujoints. I think if I would have stepped on it enough with only a 2.4 degrees of pinion angle delta, I would have exploded the ujoint or even worse, the chunk. One thing I do want to highlight from this is the 0 degree delta from the tailshaft to the driveshaft. This can actually be worse than having your pinion angle out of spec. Why? I am still trying to think that through, but its all in rotational kinematics.

Talk to me about the SS springs. Are you referring to the straps that prevent the springs from spreading under acceleration? I haven't had the opportunity to experiment with that yet. I did read somewhere that auto cars like to have them completely unstrapped from the axle back, but stick cars do not. Do you have some wisdom for me on that?




George Jets said:
Not sure that was the right fix, just masking the symtoms with the trans angle change.

View attachment 1715739683

Bad driveline angles would have shook in all gears at all speeds.

☆
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I disagree with the masking statement. Your 1st gear will impose the biggest angle change due to axle wrap due to the tall gear. I did have a very slight vibration at around 70 mph +, so that suggests that there was a very small difference in drive angle and pinion angle. The car drives very smooth now even at 80 MPH. Also, I want to point out that with such an aggressive clutch, you cannot have differentiating velocities between the tail shaft and the rear end. Differentiating velocities is a result of not having equal and opposite angles between the clutch and the driveline. This will cause the clutch to have a "skipping" affect during acceleration which is the actual definition of "jerk". This was causing the clutch to grab and let go cyclically (Shudder). That explains the entire problem. With that said, though going with less pressure plate pressure and a non-puck type ceramic clutch would have definitely gotten rid of the shuddering, it would not have fixed the fact that you still have differentiating velocities due to bad drive angle. In the end, that still would have resulted in wearing out the clutch faster. Its all dynamics. I hope this helps explain some of the situation. There are quite a few people who have had this exact same problem and was never able to fix it without swapping to a stock style clutch. If your drive angles are perfect, a puck style ceramic disc is very doable and will take much more abuse.




Dan Brewer said:
Clutch is NOT the problem. Driveshaft angles matter...especially when you get into a more aggressive clutch. Putting a rag disc back in the car with 550+ hp would have masked the problem...and resulted in the need to pull the trans once again. The OP and I worked through the problem....and got it right....problem solved.
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This is why I do business with folks that care about their customers and their reputation. You show me someone who doesn't trust Dan and I will show you someone I wouldn't pee on if they were on fire. Thanks for all the help brother.
 
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