Never in my life have I ever been called and accused of so many things as what has been posted on this thread. I just got off the phone with Walt and he asked me why I keep coming back and why I continue to help. I am beginning to ask myself that same question!

 

Hey Gus (and Walt) the detractors are clearly a small minority and most folks here certainly appreciate the efforts and inputs from both of you.


Doug

 

This a alot of energy expended over a convertible top! Walt and Gus give a system that tops off pressure at a preset level, Dennis comes up with a way to reduce overall pump pressure. Readers- pick your choice based on whatever criterea you like. Some people sell exhaust systems and other mods on this forum and don't get attacked personally because their motives are suspect. I don't want anybody not feeling welcome as everyone here has made this a great forum. I'd be out $$$$ if you all weren't pitching in. Maybe we can get together with the president over a beer!

 

Ok so this is a biggg thread, and I'm positive I haven't read every single word ( just the highlights of 19 pages !! ) but I honestly can't see where anyone anywhere has called anyone a liar or a cheat?

People possibly and very warily maybe getting together to fact find / trouble shoot etc may not be a bad thing, but, as Mike and more than a few others here have said repeatedly.........

You guys who have offered these fixes for these issues are fantastic and appreciated here......end of!

As stated, readers, take a long hard look and make up your own mind which system you may prefer.....you pays your money you takes your chances, simple

 

We need you, Gus! And I don't even have a damn convertible. Which begs the question, why would I be on this thread?

Who knows. But Gus, you're one of the guys that makes this forum great. THANK YOU.

 

+2...Thanks!!
I wish that this issue could just fade so the usual and congenial atmosphere of this forum can resume. It would be a real shame to lose members with so much valuable experience and information to contribute. Just call a truce and let each faction go merrily on their way without further attacks that lead to nowhere. Just my 2 cents.........................

 

I have one question for Gus and Walt: If the resistor does not reduce the pressure, then how did it cause Gus' roof to stall? Because you can't have it both ways. Either it reduced the pressure to the point of causing Gus' roof to stall, or Gus' roof never stalled.

 

I agree with you, cpm, however, every time the word "resistor" is mentioned, Gus has to start criticizing it. No one on this forum has ever criticized the relief valve. Everyone recognizes it as a perfectly acceptable way to reduce the hydraulic pressure. I know Dennis would like the argument to end, but every week or two Gus has to start it up again.

And look... I've said several times that I think the relief valve is the superior solution, but it also costs about 30 times as much as the resistor, and it's a lot more difficult to install.

 

I think what was happening when the resistor was first introduced was a questioning of the particulars rather than a criticism. There were also a bunch of questions when the relief valve was being developed but the voluminous back-up information and data that was presented at the time by Gus and Walt pretty much precluded questioning once the valve was available. That was not nearly the case with the resistor solution. The "back-up" for that basically consisted of "trust me--it works".

At the risk of all it would take at this point would be a graph using Gus' equipment (or something similar that is sophisticated enough to capture the pertinent data) that shows pressure versus time performed in the presence of or to the satisfaction of some impartial 3rd party.


Doug

 

It is no secret that I will answer questions and at times the questions may be difficult and I try to answer them correctly and accurately. If you take that as criticism I am sorry, but, “Don’t ask the question if you don’t want to hear the answer”!

Results of our testing http://jagrepair.com/VoltageReductionSysXK8%20R.htm

 

Repeating myself, but the idea of having a 3rd party verify one's measurement results is SOP, and seen as valuable by (best I can recall)every engineer I've worked with. Why would anyone see this as an attack?

I'm looking forward to new measurements, as they may point up some mistake I've made ... or may confirm my results.

On the discussion of gauge inaccuracies: yes, all valid, it seems to me. But consider the difference between accuracy and resolution. My gear clearly had big inaccuracy. What better gear saw as ~1600 PSI, my gear reported as ~1350. Poor accurcy.

But the resolution -- ability to detect change -- is much better. Even before installing any resistors, I could see a clear, repeatable change of ~150 PSI on the gauge by going from engine-on to engine-off, a voltage change of ~1.5 volts. Gauge inaccuracy cannot explain this! Only some actual pressure change could produce this result.

This I saw, and see, as pretty good "proof of concept" showing that voltage effects pressure.

So let's get the new measurements! This will enable many people here to devote more time to their families, and to working on their cars.

 

Will this ever end? If you're as tired of it as I am, maybe just scroll to the last paragraph.

I waited to comment on post #359 above, thinking one of the bosses here would object to stuff like "bailing wire" and "cheap ***" contained in it. But there it sits, so I'd like to have my say about it.

As always, no criticism here of the relief valve; it's a tried and true method. It is also fair to note that it's a somewhat dated method, as car manufacturers no longer use it for convertible tops (unless I've missed one). Instead they use electrical control, so I guess it's OK if we at least consider that alternative too.

Electrical control is well-established, and uses the principle that by lowering voltage we can lower pump pressure. This has cost and other advantages. The most common way to do it uses an "ECU", a fancy name for a programmable device that reduces voltage. If used with a pressure sensor, an ECU can very accurately control pressure, the best way to go if we're not worried about cost.

Cost. This brings us to ... series resistors (which some call "bailing wire").
Also an established technique, and others who've used it probably didn't think of it as cheap. I sure don't. Not as good as an ECU, since you can't change anything in real-time. But you can get pretty much any pressure reduction desired by choosing the right resistance. We're told that we become "cheap asses" if we choose this method over one costing ~ 20 times as much. I can live with that.

(Our application was criticised for the resistor being in the circuit full-tme, vs. only at latch-closure time. OK, if someone wanted to, it would be easy to use a relay and switch the resistor into the circuit only when the latch is being operated (the latch solenoid tells us when). Not needed, IMO, but easy. Doing this would raise the cost of the resistor method to ~$20. On the plus side, one less thing for critics to tell people to worry about.)

Again, an ECU is more flexible, but the pump can't tell whether the voltage applied to it arrived through an ECU or through series resistors. It just sees voltage.

Competing ideas about voltage and pressure:

I bet there are two data points all here would agree on: our pumps can make about 1600 PSI at alternator voltage, and 0 PSI at 0 volts. But that's where agreement ends.

My view is that peak pressure must change in a continuous way from 1600 to 0 PSI as voltage is reduced from 13.5 to 0 volts. (Picture a smooth curve on a graph connecting those two points.)

As I understand it, the valve team says peak pressure stays at 1600 PSI as voltage is lowered to 13, 12 ... 8 volts. (If correct, the resistor method will not work with this pump.) I don't know at what voltage they say pressure will change ... 7 volts? 1 volt? 0.1 volt? ... but it has to go down at some voltage, since we know it will be 0 PSI at 0 volts. (Picture a graph with a flat plateau region at 1600 PSI, then a sloped region down to 0 PSI at 0 volts.)

One (or both) of these views must be wrong, which is what measurements are about.

Measurements:

My measurements:
Discussed here before. Just one thing to reiterate: all theorizing on being fooled by gauge error fails in the light of one simple measurement. Forget the resistor; just measure pressure with the car's engine on, then do the same engine-off. I've done this many times and indicated pressure changes by 100-150 PSI. Engine-on, pressure goes up; engine off, pressure goes down.

Now: an inaccurate gauge may misstate the amount of change, but it cannot go up and down on its own. Only some real pressure change explains this result. (This is consistent with my idea of smooth pressure change v. voltage; it is inconsistent with pressure staying constant as voltage is changed.)

It would be great if someone with measuring gear would try to duplicate this result. No resistor needed. It would tell us a lot.

Measurements by others:
These seem to conflict with what's above. 1578 PSI pressure was reported with a resistor in place, and so it appears the resistor did not reduce pressure by much at that point. These measurements may be accurate but, as described, there are (easily corrected) issues which could allow error sources to creep in.

- No baseline reported: It is always (always!) best practice to first do a "baseline" measurement, then measure the device under test (DUT) under exactly the same conditions. Here this would mean measuring the pressure for the "stock" system then comparing that result to one with the resistor in place ... both done using the same measurement gear on the same car. Only this way can we strip out all the variables other than the DUT. It's best practice to repeat a few times ... baseline, DUT, baseline, DUT ... to be sure nothing is drifting. Any new measurement should include a baseline.

- No voltage measurement: for this DUT, it's vital to measure pump voltage along with pressure. Only this way can we assure that the resistance is what we think it is, and is installed and working properly. A 0.20 ohm resistor should yield at latch closure ~ 9 volts engine-on, 8 volts engine-off. Any new measurement should include a pump voltage measurement.

- [edit] forgot this earlier: the measurement was done under alternator voltage, whereas battery voltage is specified for this system. The lower voltage is part of the "recipe" for presure reduction.

- This may have been done (wasn't discussed), but it's important to let the resistor cool between measurements.

Will this ever end?

Gawd, I hope so. But more arguments about what we think is happening will lead nowhere. People are dug in and nobody is going to change his mind based on that.

I believe there's ample evidence that voltage control of pressure does work for this pump (the above, plus user experience with latch closure, discussed in other posts). If measurements can be done stripping as many potential error sources as possible, one set of ideas must eventually prevail, the other fail. This seems the only way to end this. I hope somebody will do the most accurate measurements possible and report them in detail here.

 

Less words--more graphs!


Doug

 

It'd be nice if some really knowledgable people could work together on this issue for ALL OUR sakes, for Jag owners and forum members alike. It would be amazing if this could happen.



As it stands there are now several threads dedicated to this issue, and back n forth it goes. All mods will be made aware to check these threads constantly, any bickering, name calling of any kind etc to be removed, infractions given, threads will be closed and persistant offenders removed from the site.


From today, edits will be made, posts removed as deemed necessary, infractions given and more, with regard to these threads, without any further warnings, so please try to get along!


Personally, I'd much rather go with option 1 if humanly possible

 

I have a question... If a member was to point out an obvious fallacy in another members statement, is that something that would warrant an infraction? For example, let's say in one post hypothetical member "G" said "I installed the 'Ultra-Bass Blaster Module' and it blew my speakers! Don't buy it! It will ruin your speakers!" And then a few months later the same hypothetical member "G" said "I just tested the 'Ultra-Bass Blaster Module' with this fancy shmancy electronic data logging decibel meter. The module has no effect on the volume of your music. Here's a graph to prove it! Don't buy it because it doesn't work!"

And then let's say hypothetical member "R" points out that the two statements are contradictory and both of them cannot be true. Is hypothetical member "R" going to receive an infraction for pointing out the obvious deceit of hypothetical member "G"?

And then let's say that other hypothetical members run their own tests on the "Ultra-Bass Blaster Module". Those tests show that the module really does blast the bass! They post the results of their tests for everyone to see. Are those hypothetical members going to receive infractions for posting their data and showing that hypothetical member "G's" data appears to be fabricated in order to discredit another hypothetical member? Is hypothetical member "G" going to receive an infraction for his obvious slander against hypothetical member "D" (the one who invented the Ultra-Bass Blaster Module) or is he free to slander hypothetical members at will, while other the other hypothetical members receive infractions for pointing out the obvious slander?

I'm just curious. I don't want to get any infractions.

Speaking of which... what is an infraction? What happens to someone if they get an infraction?

 

Please see pm Sam.......I don't want to further dilute this thread with discussions about any other matter

Any further, non relevant posts will be removed!

 

can anybody tell me how to get rear quarter windows up if you are putting the top up manually.It costs a little more than I can afford right now to fix the automatic up and down operation of top.I believe I can bypass switch to get small windows to work I just dont know where to bypass from and to .Help me if you can I would be forever in your debt.Dealership work in my neck of the woods is just way way overpriced.Thank you in advance

 

There are left and right window up and down relays in the fuse/relay panel in the trunk. They are the half size relays. Pull the relays, up is forward, and use a piece of wire or a straightened paper clip to jump the relay socket connections for the operated relay. The contact schematics are printed on the side of the relay.

Here is the relay layout:

. . . and welcome to the forum! All the answers right here.

 

This process is further illustrated in this thread:
https://www.jaguarforums.com/forum/x...-closed-71304/

 

To get the windows up you have to make sure the right side piston is all the way up. There is a switch on the right side that tells the control that the roof frame is fully up. You can do this with a prybar. Just be careful not to tear the roof.