Convertible Top Pressure Reduction Poll
 

First, let me emphasize that this poll is not intended to bash anyone! Nor is it intended to criticize either method for reducing the pressure on the convertible top hydraulic system. I think both systems do what they are supposed to do. I just thought it would be helpful to get some empirical data on the failure rates with the pressure reducing systems installed. Please vote, even if you don't have either system installed. That way we can compare the failure rate on cars with a system installed to cars without one installed.

I picked the date of 7/1/10 as the start date for the non-equipped cars because I think that's about when the pressure relief valve came out and when the resistor discussion was going on. I don't want to clutter the data with hose failures that happened 4 years ago. I want to do an apples-to-apples comparison, and that can only be done if we compare hose failures over the same time period. Since the relief valve wasn't available 4 years ago, we need to parse those failures from the data. Therefore, if you're one of those adventurous risk-takers who live life on the edge by not installing a pressure reducing system, only vote based on what has happened to your car since 7/1/10 (That's 1/7/10 for you non-North Americans out there. July 1st, 2010)

Not sure why I voted as you can't compare the 2 different approaches imo.

For one I operate the top very often (living in a moderate climate), also when driving, so for me the resistor kit would not be an option for this reason alone. So without knowing more about the usage and climate in which the car is being used the data gathered can't be used to compare the 2 different systems imho.

Andre,

Good morning. Not sure why frequency of use or climate would steer you away from voltage reduction (nor is it any of my business) but neither of these would present any problems for it use.

Morning Dennis,

Sam's explanation for the poll is about failure rates between cars that have either done something or not. Yet he has split the 2 ways, which does less to the primary question, and I only believe if you want to understand the failures better, you need to know more about usage, climate and more (i.e. age), especially if you also want to understand if there could be a difference in failure rates between the 2 methods.

My comment as to why the resistor method would not work for me personally (regardless of what I think of both methods), is the frequent usage in combination with operating the top whilst driving. The pressure relief valve gives a constant pressure, driving or not, which can’t be achieved with the resistor method.

The sample size this poll could generate makes any conclusion you could draw from it meaningless, imo.

My guess too. But you can always try.

Especially in my situation.

I installed the resistor, about two weeks later the line started leaking. I'm sure if I inspected the failing hose the jacket would still have been brittle and cracked. Regardless of pressure reduction, mine was at the point of failure before installation, so not much either method could have prevented.

I can`t really vote on this, as I installed the valve and several months later had a small leak on the hose * at the pump end*, and I may have stressed the hose when I installed the valve. I have the premium sound with nav system that makes it hard to get the pump out to install the valve without really manipulating the pump. I now have a leak at the latch location, but it`s a very slight leak, which may be a failed latch cylinder piston seal and not a burst hose. I have not had time to check this yet.

I can't vote because I don't have an XK8:(

No reduction no failures but mine's a '97

So just reading the posts, I see one failure after installing the resistor and one failure after installing the valve. I questioned the benefit of doing either as preventive maintenance in a previous thread, but no one replied. I'm thinking if it leaks, fix it; if not, leave it alone.

Sam,

First reaction is that this poll is very unlucky for Voltage Reduction. Over the course of a year, only 2 failures showed up, and 1 of these had trouble going in.

Now we have 3 in the first 1/2 day of the poll. We may have to hire a new polster!

Click one of the numbers on the poll and it gives a list of who voted for what.

If when you added the reduction valve or the resistor if you didn't replaced hoses, this would have a bearing, on the results. If you put the resistor or the reduction valve in but did not replace the hoses, then you cannot get a accurate determination because the hoses can vary in degrees of deterioration. The poll should probably be for systems that have had hoses renewed at the time the reduction systems were installed. Just my two cents worth.

Andre,

I hope you'll trust me that I don't for a moment second-guess your choice.

I also hope you won't mind my noting that with any of these systems -- stock, valve, resistor -- the pressure varies quite a bit over the course of the raise/lower top cycle. The only time that the valve comes into play is for a fraction of a second at open/close latch, and it does indeed limit the pressure to a fixed value at that time. The voltage reduction method does this too, but the pressure limit depends on whether the car is running or not; alternator voltage making somewhat more pressure than battery voltage.

I'll stop now. I promise.

Actually, I spent the last 6 years of my prior job working with statistics every day. Since we're dealing with attribute data, a sample size of 100 data points is big enough to get a statistically significant result. Of course, more data points will give us a better result, and if this poll runs for a year or two we'll be able to say whether or not the pressure reduction systems are actually beneficial.

We have to start somewhere.

Steel pipe replacement
 

Howdy Folks:
So far so good with the valve. However, If I have a hose failure, I wonder if I could go a route similar to what I did with my 66 Skylark Conv. The plastic hoses burst (125-175 psi rating) while the pump had a rating of 450 psi. The pink Dextron rear shower only happened to me once. My fix was overkill, but much cheaper than a new plastic hose set.


The particulars on the attached photo are:

• 5/16" and 1/4" steel brake lines (will handle several thousand psi)
• 3000 psi stainless braided hose in the flex area
• pump is under mat in center of trunk area

I never had any leakage problem afterward.

Hey, the data is the data. I'm not like those East Anglia University researchers who manipulated the data to get the desired outcome. If the data shows that the resistors don't work, I'll be the first to admit it.

I have had the pressure reduction valve installed and continue to have leaking on a sporadic basis. I have replaced the hoses with 3000psi hoses, I have replaced the actuator, the fittings, and everything else along the line, but I notice the leaks happen well after the car has been sitting idle and after a hot day. (I live in the San Fernando Valley where typical summer days are in the 90's -105. I have had two shops fiddle with the tightening of the fittings, had it in the shop more than 15 times to try and eliminate the leaks, installed the pressure reduction valve and it still leaks. I, honestly don't believe the pressure reduction valve has any value in reducing leaks. I am no longer willing to take the car in again, so I just mop up the leaks and check the fluid in the trunk every so often. The whole convertible hydraulic system in this car is just a pile of crap.

Different model year cars with various spec hosing, the condition of the lines before installation, header paint color internal heat temperature difference, frequency of use, etc... there are too many variables that you really can't take into consideration. You would need, what... a few thousand polled at minimum to come to any clear-cut conclusion.

My response alone completely skews the data... even with 100 respondents, what is the margin of error? Somewhere around 4-5%?

I agree it'll be neat to look at the numbers though. :p