Convertible top hydraulics are shaping up as a major
weakness in the Bentley Azure and Final Series Corniche from Rolls Royce. These cars were built from 1996-2004 (a newer
Bentley variant remains in production today) and all are vulnerable to this
issue.
The Bentley Azure and RR Cornice are fine cars but the tops are a weakness (c) J E Robison |
Here’s the problem, in a nutshell.
The engineers at Crewe wanted to design a fully automatic
convertible top for the new Azure series.
But they did not have the resources to do a new design; they had to
adapt something else that was already out there. The Mercedes SL500-type design was well
regarded, and they chose to adapt it to the Azure body.
Unfortunately, the design didn’t work as well on the
RR/B. It’s remarkably reliable on the
Mercedes, and astonishingly flimsy and incredibly costly to fix on the
Azure. What went wrong?
There are a few essential problems. First, the systems use very high hydraulic
pressures. Older automatic tops used big
cylinders and rams. With several square
inches of ram, you don’t need very high hydraulic pressures to generate the
force to move the top. However, the
newer cars use tiny actuators hidden in the top. They are smaller, so the
hydraulic pressure needed for a given actuation force rises. Because the hydraulics are hidden, they are
often at a mechanical disadvantage (leverage in reverse) and need to push
harder to move the top.
The result: hydraulic
pressures on a 2001 Bentley convertible top can run almost 10 times as high as
the pressures on a 1987 Bentley convertible top. With that factoid in mind, it should not
surprise you that the newer tops are not as reliable.
In addition, the newer tops use automatic latches instead of
human power to pull it shut and locked.
Those latches are not as rugged as they should be. Why, you ask?
Look at a Bentley Azure and then look at an SL500. What do you see? The Bentley top is significantly larger. That multiplies the forces on every component
and it’s one more reason a reliable Mercedes design didn’t work out the same on
the RR/B.
The next problem probably started in Crewe’s engineering
department, though I doubt they would admit it.
Mercedes uses plastic lines that are impervious to hydraulic fluid, but
that material selection did not translate to RR/B. Someone there chose a hose
material that deteriorated with contact with hydraulic fluid. The result – when they get to be ten years
old you see the black rubber casings falling off the hoses, and blowouts
inevitably follow.
How do you check your convertible top hoses? Look at the hoses in the main hinge area when
the top is partly lowered. Here are
examples of hoses that are coming apart.
The upper photo is a closeup of jacketing peeling from a hydraulic hose. Failure is imminent (c) J E Robison Service |
If this problem is ignored you will see leakage, as
evidenced by the leaked oil in these photos.
Leaked hydraulic oil in the convertible top well (c) J E Robison Service |
Oil seeping from the convertible top hydraulic line bundle |
If you ignore it even longer, you will eventually be
showered with oil when a line blows under pressure and the interior of the car
is sprayed and damaged.
Header bar line with deterioration. These are the worst if they blow |
"Green showers" most often come from the header bar, when the lines above the rear view mirror blow out. The reason those lines are the first to blow is that area takes the most beating from the sun. In a hot climate that area can be over 200 degrees all day, and the oil they originally used breaks down into a green jelly that won't pump, and causes pressure surge and blowouts. Jaguar is known for having this problem too.
The new hydraulic oils are synthetic and they resist this, but the moral there is - change your top hydraulic fluid every few years, or else.
When the top is partly folded there is another thing you want to check – the cables. These new automatic tops need to fold into a tight space to be hidden under the rear deck. To do that they rely on cables sewn into the top lining. Loops of wire around those cables pull the top fabric against the bows and fold everything properly. If the cables break the top will jam in the bows, and if the bows bend as a result – you have big trouble.
The new hydraulic oils are synthetic and they resist this, but the moral there is - change your top hydraulic fluid every few years, or else.
When the top is partly folded there is another thing you want to check – the cables. These new automatic tops need to fold into a tight space to be hidden under the rear deck. To do that they rely on cables sewn into the top lining. Loops of wire around those cables pull the top fabric against the bows and fold everything properly. If the cables break the top will jam in the bows, and if the bows bend as a result – you have big trouble.
Broken stay cable on Bentley convertible top |
In most of these cars you will see leakage from the hydraulic actuators in addition to problems with the lines. Here is a set of actuators removed for service. We rebuild these units rather than replace them.
So how do you fix this? You remove the trunk lining, and the pump and lines. Open the convertible top boot and remove the top as an assembly. Remove the cover in the convertible top well, and unthread the lines there. Remove the rear seat, both side panels, the right side floor covering, and the right side dash and windshield pillar trim. Remove the windshield header bar covers. Remove the lines and remaining actuators. Replace and reassemble.
Sounds easy? Look for a job time of 60-90 hours, more if you are not experienced or run into trouble.
In the next convertible top installment I will begin to
cover the actual repair process.
This article is about the automatic convertible top system used in Rolls Royce and Bentley Azure and Corniche from 1996-2005. Check out this article for thoughts on the newer Bentley GTC convertible top and its problems
And here's an article on 1997-2005 Jaguar XK8 and XKR convertible tops - they have some of the same issues but are simpler to fix
This article is about the automatic convertible top system used in Rolls Royce and Bentley Azure and Corniche from 1996-2005. Check out this article for thoughts on the newer Bentley GTC convertible top and its problems
And here's an article on 1997-2005 Jaguar XK8 and XKR convertible tops - they have some of the same issues but are simpler to fix
Good luck
John Elder Robison
Robison Service has provided independent service, repair, and restoration for Rolls Royce -Bentley owners all over New England for over 25 years. Founder John Robison is a long time technical consultant for the Rolls Royce and Bentley Owners Club. Our company is an authorized Bosch Car Service Center. We also service Mercedes, Jaguar, Land Rover, Porsche, and MINI motorcars. We have flatbed transport throughout the northeast region, and we work with Intercity and other transporters for greater distances. We also offer pickup and delivery for cars in Springfield, Wilbraham, Longmeadow, Agawam, Westfield, Northampton, and Amherst. Our drivers are available to pick up cars in Boston, Hartford, Greenwich/southern CT, New York, Rhode Island, Vermont and New Hampshire.
4 comments:
96 Bentley Azure. My battery died and so did the program to shut my top. My top wont finish the process to close,ie its closed but wont finish the latching process. How can i manually tighten the latches or get it to happen with the button?? please help with any ideas. thanks,mark
I have a 1998 Azure. Yes you are right, the latch hose blew off leaking fluid down the pillars and centre console, I mopped it up just in time and black leather is kinder to stains. I have changed the 4 hoses in the top rail myself and they were breaking up. Replacements available in UK that are of better quality and slightly thicker. The remainder look good and I've inspected the others under the rear plastic cover and they're in good shape. The complete change out would be a huge job so I'm lucky really. Changed oil as well. All working good. Thanks for the advice as there's not much out there. And yes they're fantastic big beasts.
I am replying to a very old comment about battery dying and sync being lost.
There is a key in the toolkit that unlocks the top locks. I manually and very slowly opened the hood manually like folding it back slowly and once it dropped down I was able to close it again. Heart stopping moment. Must be a setting sequence start point. I found it's best to leave an out of sync situation for about 20 minutes probably for system to depressurise.
Hi I have a problem with a 96 azure roof. It was brought to me with no activity from the roof. How do i go about doing a diagnosis of this roof. Every thing.....fuses and switches seem to check out ok.
Does it have a system reset ? george_umo@yahoo.com
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