Author Topic: catastrophic brake failure  (Read 1119 times)

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Offline Europa73

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catastrophic brake failure
« on: Thursday,June 07, 2018, 05:44:51 AM »
Word of warning.

I thought I would take the car to work today –

Hi-way then driving in the city.

All going well then – in the city the brakes fail completely with no warning –

Swerve to miss the car in front then I roll to a stop!

Catastrophic brake failure.

The issue was – the split pin had failed and the round pin holding the pedal to the master cylinder push rod had slipped out.

Check that pin!!!!!

Popped it back in and limped to the office

That really freaked me out!!!!
« Last Edit: Thursday,June 07, 2018, 05:47:29 AM by Europa73 »
also restoring 69 Elan +2 and driving a 1975 TR6

Offline BDA

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Re: catastrophic brake failure
« Reply #1 on: Thursday,June 07, 2018, 06:04:46 AM »
Yikes! I'm glad neither you nor your car got hurt. That could have been really bad!

You might even ditch the pin arrangement all together and replace it with a bolt and a lock nut.

Offline Grumblebuns

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Re: catastrophic brake failure
« Reply #2 on: Thursday,June 07, 2018, 07:05:48 AM »
Must have been a good exercise on sphincter muscle. Was it a new cotter pin? The clevis pin is usually a slip fit on the brake pedal to the pushrod so trying to figure out the failure mode.     

Offline Bainford

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Re: catastrophic brake failure
« Reply #3 on: Thursday,June 07, 2018, 08:33:12 AM »
Very glad all ended well. Many thanks for the heads up, I'll be checking as soon as I get home.
The Twin Cam plays the symphony whilst my right foot conducts the orchestra. At 3800 rpm the Mad Pipe Organ joins in.

Trevor

Offline Europa73

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Re: catastrophic brake failure
« Reply #4 on: Thursday,June 07, 2018, 10:09:52 AM »
The offending split pin goes into the hole in the locking pin (number 5) in the diagram.

This then secures the brake pedal in place.

Having this fail did put me into pucker factor 7 and almost achieved full code brown!

If this happened only a few mins earlier - would have been on the highway!!!!



also restoring 69 Elan +2 and driving a 1975 TR6

Offline jbcollier

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Re: catastrophic brake failure
« Reply #5 on: Thursday,June 07, 2018, 11:45:29 AM »
How did the split pin fail?  I have never seen one fail unless there was some other issue.

Offline Europa73

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Re: catastrophic brake failure
« Reply #6 on: Thursday,June 07, 2018, 11:53:39 AM »
hi there - at this point I have no idea - when I get home I will find the little thing and see what went on.
also restoring 69 Elan +2 and driving a 1975 TR6

Offline 4129R

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Re: catastrophic brake failure
« Reply #7 on: Thursday,June 07, 2018, 01:44:48 PM »
Who put the split pin in place?

If they used a non-rusty pin and splayed the two parts properly, it cannot come out.

If they changed it for a P clip, and it was not a tight fit, it can slip off.


Offline jbcollier

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Re: catastrophic brake failure
« Reply #8 on: Thursday,June 07, 2018, 09:35:53 PM »
Split pins are soft steel and should have a washer when used next to moving parts.  If the brake linkage is not in perfect alignment, and virtually none are, then a sideways force is applied to the clevis pin.  This could cause the motion of the brake linkage to wear through the split pin. Thus the need for a protective washer between the split pin and the brake pushrod.

Offline rfgumby

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Re: catastrophic brake failure
« Reply #9 on: Thursday,June 07, 2018, 10:55:27 PM »
Hello,
I know how you felt! I had the same problem a few years back. Fortunately it was an a Autobahn on which a whole lane was closed because of works and I could get onto the closed lane and had mach space to let it roll to a stop.

Uwe