Quite strange ..... - Ferrari Life
 
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post #1 of 13 Old 02-08-2010, 06:22 PM Thread Starter
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Quite strange .....

While our riding in my 1999 Ferrari 456 MGTA this past Saturday, my wife and I were enjoying the company of another couple. After encountering a sharp - but expectable - bump in the road, I found the handling of the car a little strange.

I understand that the V-12 of the GTA is quite powerful, but I did not expect to be able to "kick out" the rear end with 750 pounds of people in the car, and at part throttle.

Stopping at a nearby restaurant - our original destination - I found the rear of the car (and the tyres) slathered with a red fluid. The rear of the car was sitting quite low, and the power steering reservoir was empty.

It would seem that I had oiled down the rear tyre (s), and so the handling became unexpected, if not downright unsafe.

After buying and expelling 6 qts. of Castrol Mercon V to get the car home, I jacked up the car in my garage today.

Here's what I found: (Please pardon the sideways photo's)

1) In the first photo, you can see that the alloy shock absorber body, below the spring, has SPLIT OPEN. It maybe possible to see the remains of a "red fluid" here and there.

2) In the middle photo, with the area cleaned up a little, the split may be seen a little better.

3) In the final close up picture, the split can be plainly seen. Actual measurements are about 35mm top to bottom, and 2-3mm at the widest.

It looks like I may have to replace the shock.

It bothers me to see this failure mode, since I have never seen this on a street driven car. I am wondering if I replace the shock, (at maybe $1,000 each) that this will happen again, because of an outside cause, like a bad pressure regulator, or a bad accumulator - or two.

Anybody see this on their car ?

Or a customer's car?

What is Borat to do ?
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Last edited by tz 750; 02-08-2010 at 06:29 PM.
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post #2 of 13 Old 02-08-2010, 06:54 PM
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Yikes! I can't help you with information, but it says much about your car's good ride considering it didn't seem like you came down with such force. I've always found the 456 and 612 luxurious-looking. Good luck with the replacement, and continue to enjoy that great ride of yours!

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post #3 of 13 Old 02-08-2010, 07:39 PM
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Based on the photo (extremely limited view) it looks to me more like a metalurical failure. It appears that shock tube has a welded longitudinal joint that failed. Thats exactly how boiler tubes fail. I assume it would be very uncommon for a shock to fail like that.

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post #4 of 13 Old 02-08-2010, 08:56 PM
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Quote:
Originally Posted by tz 750 View Post
It looks like I may have to replace the shock.
Yeah, I would say that's a given. I've never seen anything like that happen before.

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post #5 of 13 Old 12-12-2011, 07:07 AM Thread Starter
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Super Squirt behind the wheel........

Friends: I have neglected to update this thread,
but have done so on another web site, That Has No Name...

Very strange ....... - FerrariChat.com

The aftermath explored in almost excruciating detail.

Your thoughts ?


* * * *

Car is running fine, handles well, and goes like stink.

Now my daily driver.
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post #6 of 13 Old 12-12-2011, 08:15 AM
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I found your investigation most interesting.

The process of elimination you employed was most interesting........however the last post on your thread the Venezuelan mechanic alleges to have had 2 failures with no seal destruction.
I cannot see how the accumulators seizing up would force the tube to rupture so it looks in his case that there may well be something else that might well assist you to definitely get the answer...if not already gotten..

I do not recall reading about the accumulators being tested
But......let me see if this makes sense to you.........the accumulators are nitrogen filled .....what if one of them let go and added to the pressure already exerted by the pump? Is that a possibility?
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post #7 of 13 Old 12-12-2011, 08:32 AM
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I wonder what your friends ATE before that happened.... :-D

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post #8 of 13 Old 12-12-2011, 08:40 AM
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I'm sure Taz and rifledriver/brian who did respond to your thread might have input . the steering in rear shocks if I recall correctly share the same fluid. but my question is more this I have dialed my rear shocks too hard only which I'm sure is not a good move but I like that ride a lot better seeingly your catastrophic problem I wonder if too much pressure from a hard shock would do this to me. not want to hijack just wondering if you to dialed yours too hard or left it in the middle .

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post #9 of 13 Old 12-12-2011, 10:13 AM
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That kind of internal rip is caused by excessive hydraulic pressure likely caused by the pressurized gas in the accumulators and/or in the bottom chamber of the shock absorbers being absent. This gas provides two functions, it pressurizes the automatic transmission equivalent fluid, shared with the power steering pump, for the self leveling function and also provides damping to prevent excessive hydraulic pressure as the shock absorbs impacts and moves vertically. If either is compromised, it is possible to get excessive hydraulic pressure, which splits the aluminum shock bodies.

Solution would be to get new accumulators, which are shared with high end BMWs at a much lower price, and have the shocks themselves rebuilt by Delta Vee, who have their own proprietary seals that last much longer than the Bilstein seals. I am not certain even Delta Vee can repair burst shock absorber bodies, so it would be best to ask them.

Regular changing of the power steering fluid and bleeding of the self leveling system will help prevent reoccurence. The maintenance schedule calls for changing the fluid every two years, but based on the problems people are seeing, I would go along with Brian and recommend changing the fluid annually and bleeding the self-leveling system at the same time.

Brian has way more experience with these problems and can tell you what I got wrong. I just look up how they work, he actually fixes them. Our new FOA tech may also be able to add to or correct what I wrote.

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post #10 of 13 Old 12-12-2011, 12:44 PM
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So. I a constantly dialed hard shook bad.

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post #11 of 13 Old 12-12-2011, 04:51 PM
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Since I am far more likely to get hit by a meteorite than read anything at another Ferrari based website I'll just go with what is here.

The shock looks to me like a pretty obvious case of pressure related structural failure. No way can the gas loss from the accumulator be the direct cause. To begin with they never have catastrophic pressure loss. It is always a slow, gradual process. If it was sudden, all that would happen is the back of the car would bounce up a little. There is nothing but car weight containing movement in that direction and the strength of the tube can easily handle that. Come to think of it even that would not happen. The escape of the gas into the system would not result in any pressure spike. The system is already under that pressure, the gas would just go from being contained on one side of a diaphram to going into the fluid. The pressure would drop, not rise. It is like having a balloon inside of a tire and having the balloon rupture. Not going to make any difference to tire pressure.The failure could and probably was the result of the car being driven with discharged accumulators and the car hitting some nature of road surface causing a very rapid suspension compression. Without the compressible gas in the accumulator the hydraulic pressure exceeded the burst strength of the tube. In that case you have the weight of the car plus the inertia of that weight in a rapid downward motion. That could easily get to be a great deal of pressure. That would all be taking place in the lower portion of the tube below the piston. A less than perfect tube could be a contributory factor but I suspect not the primary one. The leak at the top causing the slimy shock we are seeing is on the opposite side of the piston so was not related to the tube failure.

Can't be a pressure regulator either. Weight of the car dictates pressure, not the hydraulic system. Unless of course the levelling valve was faulty and raised the rear of the car to the maximum and just continued pumping. In that case there are other components that I believe would have failed first.


Nitrogen accumulators have been used in many types of cars and have been a universal problem in all of them. In this case it is an easy way to have self levelling suspension.

Last edited by Brian; 12-13-2011 at 08:28 AM.
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post #12 of 13 Old 12-13-2011, 05:45 AM Thread Starter
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Quote:
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Since I am far more likely to get hit by a meteorite
than read anything at another Ferrari based website
I'll just go with what is here.
If you use someone elses computer,
we will never know..........
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post #13 of 13 Old 12-13-2011, 07:55 AM
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Quote:
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If you use someone elses computer,
we will never know..........


There are some things you just can't wash off no matter how hard you try.
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