Loud bang then violent shaking : MGB & GT Forum : The MG Experience

Loud bang then violent shaking #1
Vikings230 Eric Dieterich Chicago, IL, USA Sign in to contact	Topic Creator (OP) Apr 24, 2014 06:50 PM Joined 10 years ago 4 Posts

I goofed up pretty bad this time, I was driving around 50mph when all of a sudden I heard a loud band and the car started to violently shake. The whole car was shaking and the shift knob was bouncing straight up and down. I then carefully drove it to my friends house about a mile away and whenever I launched it felt like the clutch was slipping a bit. When I finally got to my friend's house I looked to see what was wrong but didn't see any immediate red flags so I went to drive it home and it would go into gear fine but the clutch wouldn't catch so I couldn't go anywhere. It would not catch in any gear, including reverse. I'm guessing that the clutch just gave out but would that also cause the violent shaking and the shift knob to bounce? I wasn't on the clutch when I heard the bang so I'm not exactly sure. What do you guys think and how screwed am I?

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Re: Loud bang then violent shaking #2
rntanner Roger N. Tanner (Disabled) Oxnard, CA, USA Sign in to contact 1970 MG MGB 1977 MG MGB	Apr 24, 2014 07:16 PM Joined 15 years ago 4,348 Posts

Jack the side of the car up a bit, so one of you can look at the clutch slave cylinder "underneath".

If: When your friend pushes down the clutch pedal inside the car, and the slave cylinder does not move, one of these four features have failed:

a) System has lost its hydraulic fluid. This includes; but, not necessarily is the only chance for a leak:

b) The hydraulic fluid flex line between the hydraulic hard line from the master cylinder, and the slave cylinder has a leak.

c) The Clutch Master Cylinder has failed.

d) The Clutch Slave Cylinder has failed.

Unless you are very short on money (try to rebuild the clutch master and slave cylinder), buy all new parts:

Master cylinder, slave cylinder and flex line.

Then charge the hydraulic system with DOT 5 Silicone Brake fluid, and you will never touch this hydraulic system again. I have driven my 1977 MGB 77,000 miles with the brakes and clutch hydraulics with DOT 5, Silicone Brake Fluid.

If you have trouble finding DOT 5 Brake Fluid, check your local Harley Davidson motorcycle dealer. Harley Davidson has been using DOT 5 for almost 30 years on their motor cycle brakes and clutches.

Roger N, Tanner, Professional Engineer, Retired
Ventura, CA USA

Roger N. Tanner
Professional Engineer, Retired

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Re: Loud bang then violent shaking #3
dickmoritz Dick Moritz Philly 'burbs, PA, USA Sign in to contact	Apr 24, 2014 07:47 PM Top Contributor Joined 14 years ago 26,273 Posts

Eric,

I'd say you're due for a clutchectomy, as it certainly sounds like a catastrophic failure of the clutch disc or pressure plate. Such a failure would cause both a bang and violent shaking since you have a lot of mass spinning loosely at enough rpm's to shake cocktails from Chicago to Dubuque...

Dick

Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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Re: Loud bang then violent shaking #4
rocannon rocannon L Comanche County, OK, USA Sign in to contact 1967 MG MGB GT "GT From Hell"	Apr 24, 2014 08:35 PM Top Contributor Joined 14 years ago 12,664 Posts

U-joint?

Let us know how it turns out.

Pogo is right.
—————————————————————-
The power of reasons is an illusion. The belief will not change when the reasons are defeated. The causality is reversed. People believe the reasons because they believe in the conclusion.

Edited 1 time(s). Last edit at 2014-04-24 08:35 PM by rocannon.

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Re: Loud bang then violent shaking #5
ca mgb darron small ramona, CA, USA Sign in to contact 1962 Triumph TR4 "Penelope" 1980 MG MGB	Apr 24, 2014 08:40 PM Joined 10 years ago 362 Posts

X2

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Re: Loud bang then violent shaking #6
ca mgb darron small ramona, CA, USA Sign in to contact 1962 Triumph TR4 "Penelope" 1980 MG MGB	Apr 24, 2014 08:41 PM Joined 10 years ago 362 Posts

with Dick.Sounds like the clutch disk came apart.

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Re: Loud bang then violent shaking #7
Steve64B Steve Opitz Phoenix, AZ, USA Sign in to contact 1966 MG MGB	Apr 24, 2014 08:44 PM Top Contributor Joined 17 years ago 11,646 Posts

BANG! Those are always fun. Next time thought park it right away, you can turn a simple repair into a really expensive rebuild even limping a small failure home or to a friends house. Best failed tool kit, AAA card, credit card and a cell phone with those you can solve any problem.

Sounds like a clutch failure, follow Rogers advice... peak into the pit of despair and see if you can see carnage. Doing a clutch isn't that hard it's the first repair I made on my first B. Great learning opportunity.

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Re: Loud bang then violent shaking #8
gooser Drake Myers Danville Va, USA Sign in to contact	Apr 24, 2014 08:47 PM Joined 16 years ago 8,331 Posts

yup. sounds like your clutch busted however do a quick eyeball and make sure you didn't throw a spark plug.

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Re: Loud bang then violent shaking #9
ShortJoe Joe S Framingham, MA, USA Sign in to contact 1975 MG MGB MkIV	Apr 24, 2014 08:51 PM Joined 10 years ago 89 Posts

I had a 4 speed gearbox in a 280z do do exactly the same thing. The transmission let go, I had 1st, and 4th gear, but they both let go on the way home. These trannies tend to be a lot more robust though.

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Re: Loud bang then violent shaking #10
nickj Nick Jenkins Novato, Marin Co, CA, USA Sign in to contact 1970 MG MGB GT 1972 MG MGB	Apr 24, 2014 09:00 PM Joined 12 years ago 2,558 Posts

A loud bang followed by violent shaking was exactly what I experienced when I blew out a spark plug. But the fact that the clutch is out does seem to point in that direction.

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Re: Loud bang then violent shaking #11
tahoe36c Paul Hruza Panama City, FL, USA Sign in to contact 1969 MG MGC GT "Little Red Rocket..." 1972 MG MGB GT "Tiny Dancer" 2002 Harley-Davidson Dyna	Apr 24, 2014 09:02 PM Joined 10 years ago 13,244 Posts

Hope it didn't trash the bell housing, etc., when she let go!

Those who confuse Burro and Burrow don't know their @ss from a hole in the ground...

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Re: Loud bang then violent shaking #12
lil.red.roadster Bernie Anderson Marshfield, Gloucestershire, UK Sign in to contact 1970 MG MGB MkII "The Beasty"	Apr 25, 2014 06:33 AM Joined 11 years ago 1,294 Posts

I had exactly the same experience:

Not funny.

Bernie

Bernie

"discere mutari est"

Wiring Diagrams: http://www.advanceautowire.com/mgb.pdf
Paul Hunts very useful site: http://www.mgb-stuff.org.uk
Manual for download: http://www.geomatique-liege.be/MGJP/DocumentsPDF/MGB_Workshop_Manual.pdf
UK MoT guide: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/518634/mot-inspection-manual-for-class-3-4-5-and-7-vehicles.pdf
Some basic guides: http://www.howacarworks.com/

1970 Roadster (First Reg July 10 1970). Std exhaust (Bell SS) AFAIK rest is bog standard

blown_clutch.jpg 40 KB

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Re: Loud bang then violent shaking #13
Jack Long Millsboro, DE, USA Sign in to contact 1955 MG TF 1500 "Harriet" 1974 MG MGB "Lucy"	Apr 25, 2014 06:52 AM Joined 18 years ago 5,017 Posts

In reply to # 2670771 by dickmoritz Eric,

I'd say you're due for a clutchectomy, as it certainly sounds like a catastrophic failure of the clutch disc or pressure plate. Such a failure would cause both a bang and violent shaking since you have a lot of mass spinning loosely at enough rpm's to shake cocktails from Chicago to Dubuque...

Dick

X2. These are exactly the symptoms I experienced when I blew up the clutch on a Spitfire. The clutch disk had a massive failure and separated from its hub.

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Re: Loud bang then violent shaking #14
Jim K James A. Krasnansky Liberty, KY, USA Sign in to contact 1970 MG MGB GT "Chloe" 1971 MG MGB GT "Roscoe" 1972 MG MGB "Camilla"	Apr 25, 2014 08:55 AM Joined 20 years ago 11,349 Posts

Very screwed. You'll need to pull the engine & transmission.

Jim K is a grease-stained wretch

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Re: Loud bang then violent shaking #15
bobmunch Bob M Ontario, OR, USA Sign in to contact	Apr 25, 2014 09:23 AM Joined 24 years ago 12,897 Posts

Similar symptoms when a driveshaft (at the U-joint) went to hell on an old truck of ours. However, if your driveshaft isn't hanging and banging around loose below the car, then probably as everyone else has said, the clutch went to hell. Photo below is what I found after a non-violent failure, yours could be worse.

TO Bearing Wreckage 2 75K miles 11 08.jpg 47.2 KB

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