Violent shaking in when taking off.

ngiotta

Member
Jan 29, 2019
18
7
13
California
Hi all,

I'm starting to get somewhat fed up with my son's 95 Cobra. We installed a brand new flywheel, clutch, pressure plate, and throwout bearing about 300 miles ago. It was running fine until last month, when the throwout bearing would squeal like crazy with the clutch pedal depressed. I removed the transmission and the clutch fork literally just fell out of the bellhousing. I found that the spring prongs that hold the throwout bearing to the clutch fork were bent and the bearing likely had popped out. I also noticed the pivot stud was worn.

So, I replaced the pivot stud, clutch fork, and throwout bearing. This fixed the problem-- until 2 days ago. Now, it's starting to make the noise again at startup and for the first 30 seconds of the clutch being engaged. What's worse, the car now shakes and bucks violently when accelerating from a standstill, until it gets up to about 10 mph. There's no more noise or shaking while driving the car around at speed. I tried taking off in 2nd gear, same bucking and vibrating.

I really don't want to be forced to swap his car to an AOD, but these problems are killing me. Anyone know what could be wrong here?
 
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08GT500

Active Member
Jul 12, 2018
873
136
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Hi,
There’s more than a few things that may cause this, but the typical issues are much less in number..
I’ll ask some questions & start with the most typical’s, (and share information why).
1) Most Common: Did you run a new Ford OE pilot bearing, and Throwout bearing- there is no equal to OE with these parts, no substitutes at these levels that will surpass OE.
2) What Mfg’s clutch Ass’y are you running? Clutch fork? Only FYI: OE had a lead weight installed inside to offset harmonics, it’s ok to run without, but clutch will feel “lighter”. You did the right thing installing a same Mfg’s flywheel, clutch disc/pressure plate. This eliminates most chatter during break in.
3) 2nd most common: Did you verify/adjust T. Bearing preload?
4) Running the stock Pedal quadrant? Have an adjustable firewall cable adjuster? Aftermarket adjustable Cable
5) What was the condition of the Transmission’s input bearing (Cone)shaft when inspected? Torqued? (Shaft surrounding the Trans input shaft, the T.Bearing travels across when actuated).
6) Transmission mount or engine mounts with damage allow excess lateral and vertical power train movement and may misalign & destroy the clutch pivot ball. May be difficult to identify in some cases. Look close, lever against mounts with a bar, check for loose/broken bolts.
Note I’m not asking about the install, specifically. We’ll go there if necessary. I believe your issue may be found in this text. Clutch may chatter a bit until the 500 mile mark.
CLUTCH PRELOAD ADJUSTMENT:
Proper cable adjustment is imperative and can take out a T.Bearing quite quickly & effectively. Almost as bad as running non-OE Bearings..
T.Bearings are not meant to run with a constant excess point load, nor growl from zero contact to engine RPM when the Clutch pedal’s depressed. Hair between.
You want the slack out of the cable and 5-8lbs of force to move the pedal 1/2”. Clutch should begin to engage about 3” from the floor. Running with no preload May allow the T.Bearing to run sloppily on the input bearing retainer shaft and wear out.
Correcting preload will shut a T.Bearing the hell up before it’s destroyed, that became quiet with the pedal pressed down at all.
For a stock quadrant/pawl, pull up on the clutch pedal to adjust it. These are semi-automatically adjustable, plastic, they do wear out, especially with higher clampforce engagement clutch loads than stock, and mileage.
I suggest running a Steeda 6061-T6 Aluminum pedal quadrant with an adjustable Firewall clutch cable adjuster if you find the adjuster is no longer doing it’s job.
Example.. https://lmr.com/item/MM-MMCP51/Maximum-Motorsports-Mustang-Clutch-Cable-Kit
MM will have what you need, below is a link to a quick but detailed run through to properly adjust/verify preload adjustment of your T.Bearing to your clutch fingers, step by step.
https://www.maximummotorsports.com/How-to-Adjust-a-Mustang-Clutch-Cable.aspx

Post your findings, good luck!
-John
 

ngiotta

Member
Jan 29, 2019
18
7
13
California
Hi,
There’s more than a few things that may cause this, but the typical issues are much less in number..
I’ll ask some questions & start with the most typical’s, (and share information why).
1) Most Common: Did you run a new Ford OE pilot bearing, and Throwout bearing- there is no equal to OE with these parts, no substitutes at these levels that will surpass OE.
2) What Mfg’s clutch Ass’y are you running? Clutch fork? Only FYI: OE had a lead weight installed inside to offset harmonics, it’s ok to run without, but clutch will feel “lighter”. You did the right thing installing a same Mfg’s flywheel, clutch disc/pressure plate. This eliminates most chatter during break in.
3) 2nd most common: Did you verify/adjust T. Bearing preload?
4) Running the stock Pedal quadrant? Have an adjustable firewall cable adjuster? Aftermarket adjustable Cable
5) What was the condition of the Transmission’s input bearing (Cone)shaft when inspected? Torqued? (Shaft surrounding the Trans input shaft, the T.Bearing travels across when actuated).
6) Transmission mount or engine mounts with damage allow excess lateral and vertical power train movement and may misalign & destroy the clutch pivot ball. May be difficult to identify in some cases. Look close, lever against mounts with a bar, check for loose/broken bolts.
Note I’m not asking about the install, specifically. We’ll go there if necessary. I believe your issue may be found in this text. Clutch may chatter a bit until the 500 mile mark.
CLUTCH PRELOAD ADJUSTMENT:
Proper cable adjustment is imperative and can take out a T.Bearing quite quickly & effectively. Almost as bad as running non-OE Bearings..
T.Bearings are not meant to run with a constant excess point load, nor growl from zero contact to engine RPM when the Clutch pedal’s depressed. Hair between.
You want the slack out of the cable and 5-8lbs of force to move the pedal 1/2”. Clutch should begin to engage about 3” from the floor. Running with no preload May allow the T.Bearing to run sloppily on the input bearing retainer shaft and wear out.
Correcting preload will shut a T.Bearing the hell up before it’s destroyed, that became quiet with the pedal pressed down at all.
For a stock quadrant/pawl, pull up on the clutch pedal to adjust it. These are semi-automatically adjustable, plastic, they do wear out, especially with higher clampforce engagement clutch loads than stock, and mileage.
I suggest running a Steeda 6061-T6 Aluminum pedal quadrant with an adjustable Firewall clutch cable adjuster if you find the adjuster is no longer doing it’s job.
Example.. https://lmr.com/item/MM-MMCP51/Maximum-Motorsports-Mustang-Clutch-Cable-Kit
MM will have what you need, below is a link to a quick but detailed run through to properly adjust/verify preload adjustment of your T.Bearing to your clutch fingers, step by step.
https://www.maximummotorsports.com/How-to-Adjust-a-Mustang-Clutch-Cable.aspx

Post your findings, good luck!
-John

Thank you for your thoughtful response, John.

1) New stock Ford pilot bearing
2) New Exedy Stage 1 Clutch / Pressure Plate / Flywheel combo
3) New Timken TO bearing
4) New BBK quadrant, firewall adjuster, and Ford cable
5) I haven't checked the input bearing, but there wasn't any noticeable play. It's the Cobra trans which also has the steel retainer plate.
6) Mount looked a little soft, but no cracks. Crossmember is good.

The clutch is at about 400 miles now and only just started the shaking behavior. I wouldn't even call this chatter. I've experienced chatter with other clutches in some my other Mustangs in the past. This is violent shaking.

I just dropped the car off at the shop that originally installed the clutch, as it's readily apparent that the transmission needs to come out again and I just don't have the want or the will to do it again, after just doing it last month. I will definitely post what the issue was, so that just maybe, it will help someone else that experiences this issue in the future. Thanks again, John!
 

ngiotta

Member
Jan 29, 2019
18
7
13
California
So... here's the first update. The shop I took it to, said that with the inspection cover off they can see sparks coming off of the clutch assembly when it is engaging. They said that it was going to be $850, just in labor to pull it out and put it back in. Parts are extra. It was only $480 last year when they did the job originally. Apparently, their labor rates went up to $155/hr this year... Gotta love California. I told them I'm coming to pick it up and will just do it myself. I don't know whether to hate myself for being a cheapskate, or pat myself on the back for not letting them take advantage of me.
 

08GT500

Active Member
Jul 12, 2018
873
136
53
49
Massachusetts
Thank you for your thoughtful response, John.

1) New stock Ford pilot bearing
2) New Exedy Stage 1 Clutch / Pressure Plate / Flywheel combo
3) New Timken TO bearing
4) New BBK quadrant, firewall adjuster, and Ford cable
5) I haven't checked the input bearing, but there wasn't any noticeable play. It's the Cobra trans which also has the steel retainer plate.
6) Mount looked a little soft, but no cracks. Crossmember is good.

The clutch is at about 400 miles now and only just started the shaking behavior. I wouldn't even call this chatter. I've experienced chatter with other clutches in some my other Mustangs in the past. This is violent shaking.

I just dropped the car off at the shop that originally installed the clutch, as it's readily apparent that the transmission needs to come out again and I just don't have the want or the will to do it again, after just doing it last month. I will definitely post what the issue was, so that just maybe, it will help someone else that experiences this issue in the future. Thanks again, John!
Hi, Always welcome!
Back in your hands? No- great thing! <Pat>,
Pony, too. <Pat>. Wanted to help more.
My guess is the thought of irritation will be short lived, as you close in on the culprit, vindicated once unveiled by your own hand. (And have some extra cash).
I’m ready to offer any assistance, just say the word. Will reserve comments until it’s apart & all is in the open.
You did the right thing, once you’re back into it again, any doubt’s whether you made the right move or not will fade away..
Think of how much more help this will be to someone else as well, perseverance!
My 96’ for support...
22533A1F-72DD-40DC-8FEB-42A0AAF1F58C.jpeg
Best!
John
 
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Potomus Pete

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Pat yourself on the back. Patience and organization will get you there. Safety first . I really enjoyed doing mine. Reminded me of when I was in high school over ,and over. again.
 
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Noobz347

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the car now shakes and bucks violently when accelerating from a standstill, until it gets up to about 10 mph.


Check your U-joints too. Get under there and shake the living :poo: out of it.

I had a u-joint [reveal] itself during a clutch swap once. Drove me nuts until I figured out it had nothing to do with my install other than being removed and reinstalled.

2 u-joints and couple beers put me back in business. I hope it ends up being that simple for you as well.
 
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08GT500

Active Member
Jul 12, 2018
873
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So... here's the first update. The shop I took it to, said that with the inspection cover off they can see sparks coming off of the clutch assembly when it is engaging. They said that it was going to be $850, just in labor to pull it out and put it back in. Parts are extra. It was only $480 last year when they did the job originally. Apparently, their labor rates went up to $155/hr this year... Gotta love California. I told them I'm coming to pick it up and will just do it myself. I don't know whether to hate myself for being a cheapskate, or pat myself on the back for not letting them take advantage of me.
It’s all good! :cheers:
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
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I don't know whether to hate myself for being a cheapskate, or pat myself on the back for not letting them take advantage of me.


You'll only hate yourself until it's done (correctly because you're the one that did it). Then you'll high 5 whoever the hell happens to be there when you get it buttoned up and running right.

Sounds like father/son project marathon :nice:
 
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90sickfox

I didn't really have an issue with the stink...
SN Certified Technician
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I've seen the springs in the Exedy clutches break and come apart. It threw sparks and made one hell of a racket too. Does your son like clutch dropping from a stand still ? I'd check the rear tires for straight lines around the tread. Might need a stronger clutch to handle his left foot. 500 miles is supposed to be break in easy driving range.

At one time we have all pushed these cars to the limit. Could be a manufacturers defect.
 

ngiotta

Member
Jan 29, 2019
18
7
13
California
I've seen the springs in the Exedy clutches break and come apart. It threw sparks and made one hell of a racket too. Does your son like clutch dropping from a stand still ? I'd check the rear tires for straight lines around the tread. Might need a stronger clutch to handle his left foot. 500 miles is supposed to be break in easy driving range.

At one time we have all pushed these cars to the limit. Could be a manufacturers defect.

Yeah, 08GT500 mentioned that is a problem with this brand as well. I'm on vacation next week and will have a chance to drop the trans out. I will then post pictures of the Exedy components on here to both publicly shame them and maybe help someone save some money in the future.

It's possible that my son punched it a time or two without me in the car, but I certainly hope not. He knows the engine has to be broken in first, or I'll wring his neck. :)
 

2000xp8

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I wouldn't worry too much about break in if it wasn't completely abused for the first few hundred miles.
Cars go directly from build to dyno all the time...
You think any teenager with a mustang broke the clutch in correctly 25 years ago? doubt it.
 

ngiotta

Member
Jan 29, 2019
18
7
13
California
Okay guys, I got everything out. Honestly, it looks pretty good still. The bellhousing wasn't on very tight, but wasn't loose. Anyhow, as promised here's pics of everything, including the new McLeod clutch set, side by side with the old Exedy clutch set.

Back together it goes!
 

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ngiotta

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Jan 29, 2019
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California
I wouldn't worry too much about break in if it wasn't completely abused for the first few hundred miles.
Cars go directly from build to dyno all the time...
You think any teenager with a mustang broke the clutch in correctly 25 years ago? doubt it.

I was more worried about him breaking in the brand new engine, than the clutch. ;)