Secondary Actuators, Upside down or Not
 

In the "Dreaded No Start" Thread, I had asked about the misalignment on the secondary Actuator linkage as found on My 91.


Linkage as found
http://i145.photobucket.com/albums/r...ps1a65c048.jpg

To Me it appears that it would cause binding of the linkage and abnormal stress to the diaphragm. So I removed one and tested both with a vacuum testor, neither appeared to bind in any way, and the vacuum required for full travel was the same on each one.

Actuator rotated 180 deg to straighten alignment.

http://i145.photobucket.com/albums/r...ps0e890319.jpg

I gather there are differing opinions regarding which is the correct mounting.

Re: Secondary Actuators, Upside down or Not
 

Good Stuff Bearly Flying :thumbsup:

That is what I found also....... but what appears below is actually an incorrect installation (Not angled shaft). However, this incorrect installation seems to work fine (using New Canisters)......which when I get back to the 90' I will verify one more time.

Secondary Canister Installation
Secondary Canister Installation FACTS TIPS

This Canister Installation (New Canisters) would be wrong but I will check operation as I can pull Plenum in 10 minutes :D

http://i287.photobucket.com/albums/l...0c42a1d226.jpg

I have modified Canisters in the past by filing just a tad on the arm edges where they might bind with the Canister opening.

http://i287.photobucket.com/albums/l...b65fab8e8b.jpghttp://i287.photobucket.com/albums/l...473435cbfa.jpg

So....I could install the Canisters either way since they are new as what appears to be wrong above (top photo) actually seemed to work perfectly before I installed the plenum :p

Re: Secondary Actuators, Upside down or Not
 

Dynomite, I had seen your pictures previously, ( Thanks for all your solutions threads, I have read quite a few so far.)

The angle of your picture made it hard to tell which orientation yours are in. So I thought I would take a couple more square on to illustrate the difference.

Re: Secondary Actuators, Upside down or Not
 

They were straight (not angled) in the installation of New Canisters on the 90'

Great photos you have in your first post.....thanks :thumbsup:

WVZR-1 background information and analysis is appreciated :handshak:

Re: Secondary Actuators, Upside down or Not
 

As Posted by Jerry;

By request from the OP, Barely Flying, please find the following, FACTUAL information regarding "Secondary actuators installed backwards at the factory";

In actuality, this is simply not accurate.

Chris Allen, Assembly Manager and Scott Skinner, Engine Building Supervisor, were Mercury Marine employees on the LT5 project. I am proud to say that both are good friends of mine. I also personally know several of the girls who worked on the LT5 assembly line. My information comes directly from all of the above.

The facts are:
1. The linkage arm sits to one side of center due to an "L" bend in the arm for attachment to the actuator diaphram.

2. The actuator was initially installed with the diaphram linkage "straight in line with the secondary linkage bellcrank.Binding/dragging was evident, so the actuator was turned over to align the center of the actuator diaphram with the bellcrank. The linkage was angled but the pull was straight and aligned with the actuator. No more binding, quicker & smoother operation.

3. The LT5 was essentially a hand-built engine produced to race engine tolerances, by Mercury employees who filled voluntary positions with no guarantee that the positions they were leaving, earned by time & performance, would be available to them after the LT5 program was completed. They were a team of highly skilled and motivated personnel.

4. The ocassional posts about "a woman" doing sub-standard work is unfounded and unwarranted. To further promote baseless rumors only serves to promote mis-truths about the LT5 and cast an undeserving bad light on individuals who consider the LT5 program at Mercury Marine in Stillwater, OK, the highlight of their entire career.

THE BOTTOM LINE: The actuators work best and are supposed to be installed with the linkage bar angled to the secondary linkage bellcrank, to achieve a straight pull from the diaphram. Do not rotate the actuator to obtain a straight linkage bar.
__________________
Jerry Downey
JERRYS LT5 GASKETS & PARTS
http://www.jerrysgaskets.com

Re: Secondary Actuators, Upside down or Not
 

OK thanks to the OP in post 1 we see the backward install.
In post #2 we see a correct install.
By correct I mean one that does not bind (due to filing the edges
of the L bracket) and does not deflect the diaphragm at a angle.

Of course anyone can leave the actuators in wrong and justify it by knowing someone at the factory thought it was best but to me the issue
is one of root cause analysis. This was NOT done evidently in the factory.
Only an expedient solution was used. Root cause would be the excess metal at the short part of the L bracket. (I used a cut off wheel to remove the metal)

This is how I solved the problem and have not had sticking actuators since 98. It's good to see others have also come up with this same fix independently.

Bottom line there is no need for insults or cheap shots.
We can stay on topic and lay out what we know then let all who
read choose their solution.

Re: Secondary Actuators, Upside down or Not
 

Actually Scott, after reading Jerry's post, I went back and tested the two actuators in their opposite positions, as per my photo's.

WVZR-1 and Jerry are correct, altho the linkage appears to be offset, it is pulling evenly on the diaphragm.

I shone a flashlight into the opening around the arm and watched while slowly increasing the vacuum, the diaphragm pulls evenly throughout the stroke.

I think what screws with your mind , is the arm moving across the face of the canister as it pulls back, but the distance between the diaphragm and the pivot does not change, therefore the angle will be consistent.

I think I will let sleeping dogs lay and keep the original orientation.

Thanks for all the insight and suggestions.

Don

Re: Secondary Actuators, Upside down or Not
 

Interesting observation. Can't say it agrees with what I saw
Think if the short part of an "L" if the long part is slanted then
the short part also is. The short part is connected to a flat washer
on the other side of the rubber diaphragm. Since the washer is held
at the same angle as the crooked L then the rubber is not pulling
evenly all the way around.

The statement "the diaphragm pulls evenly through out the stroke" is an interesting conclusion. How did you determine this? Did you measure? I know my eyes are just not good enough to see a 1/16in deflection difference. If you release the long part of the L from the ball stud where does the straight part point? Is it still crooked? What would pull it back straight? The deformed rubber maybe? hmmmmm

I think I understand why you're making that decision.
Yes, it's bound to work out just fine for you.

Re: Secondary Actuators, Upside down or Not
 

Scott, I watched the diaphragms as the vacuum pulled back on the linkage, there was no apparent changes to the diaphragm, buckling or stretching that I could observe. No I did not measure anything, I'm not equipped to get that detailed in my garage.

My initial thoughts were that the diaphragm was being stressed by the sideways motion of the arm, but that is not the case as far as I can determine. When the diaphragm first starts moving the arm does move as it centers itself, but it does that in either case, after that the arm moves in a linear path, no sideways movement at all. There is a slight vertical movement due to the arc of the bellcrank, but again it is the same in either case.

If there is anything else you can think of to test, I have everything exposed now.

Re: Secondary Actuators, Upside down or Not
 

You might do a leak down test of each diaphragm. Since these kind of actuators are specifically designed for a straight and linear pull your eventual failure will be a leak. Also while in there I'd put a new check valve in. That is where dirt likes to accumulate. And look for any arcing evidence on the ignition wires. I like to wipe them off and inspect that they are down all the way on the coil.

Re: Secondary Actuators, Upside down or Not
 

Ideally, if the actuator arm was a rod, connected straight through the center of the diaphram and perfectly aligned with the linkage bellcrank, then there would be no controversy, but it's not.

As it is, the actuator arm is an "L" bar and the linkage arm is offset from its connection at the center of the diaphram. when the actuator arm is aligned with the bellcrank, the center of the actuator diaphram is not aligned. As such, the pull is angular when vacuum is applied to the actuator.

As Bearly Flying observed, when the arm is "angled" to the bellcrank, the center of the actuator diaphram is in alignment and the pull is straight when vacuum is applied to the actuator.

When the actuator is installed with the linkage arm "straight," you can see the diaphram move angular in the housing as vacuum is applied. This is evidenced by the need to grind & remove metal from the arm to clear the actuator housing when vacuum is applied.

Scott, Your analysis would be correct IF the linkage arm fitment to the bellcrank shaft was such that it forced the arm to remain perpendicular to the bellcrank attachment pin. It is not however, as it fits loosely enough that it works more like a flexible ball chain than a connecting rod.

On my 60K mile 94, I tested the actuators as they were installed "angular" and reversed "straight." "Angular" operated smoothly and quickly, "straight" was jerky & took slightly more vacuum to open fully.

I consider Gorden Killebrew a good friend and a true genius on the C4 Corvette from bumper to bumper, but he was responsible for propagating the "installed backwards at the factory" myth. He is incorrect in this assumption.

The angular linkage arm does look "wrong" but in reality it is not installed upside down and it works perfectly in that configuration. Most importantly, it was purposely designed & installed that way.

Re: Secondary Actuators, Upside down or Not
 

Yes most likely. This approach would have been a proper design.

Only if the top of the L where it connects tot he linkage is left unbent. Read on.

Not my observation. As the pull occurs from this noticeably off center angle. the ball travel is interrupted toward the end of the travel. This puts a lateral stress on the diaphragm. It's really hard to imagine anyone thinking this was engineered this way. More like it was overlooked this way.

Not my observation. The metal would need to be ground down even if the off center pull was left in because the actuator is upside down.
It simply makes contact with the side of the actuator regardless of the angle.

Ah but you missed the fact the the angular travel eventually is severe enough to run to the end of the ball travel. That is where the sticking can occur. (video is needed here)

Also the perfect L has to be altered to a more acute angle when the
actuator is installed right side up (so pull is straight looking)
This puts the top of the L in alignment with the center of the diaphragm. (THIS IS THE KEY POINT)
I must admit I forgot about this bend until now. I remember bending a part but could not remember which.

On my 90 I tested the actuators installed upside down and found at the end of the travel the assembly would stick. Once I had the part out I could see the rubbing of the L bracket and concluded it was because the actuator was upside down. I reversed it and noted as you that the pull was jerky. I then bent the L bracket and walla. A straight pull and straight appearance. Complete root cause analysis AND fix.

He is absolutely correct but incomplete on the fix. The offset angle caused binding toward the end and is also visually upsetting. Poor fix at best to leave such a crappy looking assembly in place. AND I just know it was not designed that way. (original drawings) It was, even by your story, a problem area whose solutions was questionable (put the actuator in upside down) at best. That is not design or engineering. That is expediting a possible fix on the assembly line. Somebody's good idea.

Not my understanding of the word "perfectly". The ball runs out of angular travel when the actuator is installed upside down.
I do agree is was purposely installed that way.
I do not agree it was designed that way. I think it was left that way.
Lack of time or ? to do a proper fix.

In summary:
This discussion has brought back to memory the step by step approach I took in resolving what at the time, seemed to be an assembly error. Little did I know at the time that the fix I made would lead to:
1. 10yrs of reliabiliy
2. aesthetically NOT upsetting appearance that will confound future owners.

I recommend that everyone leave the actuator looking crooked (upside down) unless you are willing to at least bend the L bracket such that the top end of the L be aligned with the center of the diaphragm.
If you do so you'll have a visually pleasing appearance AND reliable operation.

Re: Secondary Actuators, Upside down or Not
 

Great Description and explanation Jerry :thumbsup:

I (because I am a Pirate) install the canisters with straight link back to the pivot linkage. I file the canister link arm if I notice it is even close to touching the canister opening.

I install the link straight back to eliminate any sidewase thrust on that little link keeper on the pivot linkage shaft. That is the Pirates way :D

Cliff

1990 LT5
http://i287.photobucket.com/albums/l...d107332bc7.jpg

1991 LT5
http://i287.photobucket.com/albums/l...510aaf14f2.jpg

Re: Secondary Actuators, Upside down or Not
 

Here is a diagram to better show how the straight pull is accomplished
by bending the L bracket after putting the actuator in right side up..
Note as so many have noted (not just Gordon Killebrew) the upside down
actuators are visually upsetting. The bent L bracket is less so as well as
fixing the problem of hitting the end of the travel on the ball socket.

http://zr1.net/forum/picture.php?alb...pictureid=2234

Re: Secondary Actuators, Upside down or Not
 

Scott, if you're happy, I'm happy and I will respect your EE skills and hope you can respect the ME skills which are a portion of my PE skills.

Out of respect for a significant volume of empirical data (6,000+ LT5 engines with "angled" actuator arms) the angled actuator arms work just fine.

if the "angled arm" visually bugs anyone, then by all means, rotate the actuator, increase the right angle on the linkage arm to an acute angle but don't forget to straighten it at the end so it is perpendicular to the bellcrank pin. BTW, there is no ball socket at the attachment to the bellcrank.

Re: Secondary Actuators, Upside down or Not
 

not sure skills come into play only facts should.

I totally agree. That is why on a previous post I recommended leaving it as is if one was not willing to modify the L bracket.
The upside down actuators work but they are problematic both visually and functionally (end of throw binding)
As with other design issues on the car. They can be and have been improved (fixed) by many of us.

Yes, I mostly agree however, the angle on the L bracket needs to decreased (accute) not increased (obtuse).
A bellcrank is composed of several components. the L bracket connects to the bellcrank through a "king pin" or "ball socket". A bellcrank is the arm part. On many bellcranks there is a shaft connection point. In our cars a king pin is used at the "moving pivot" point.
See this figure for info:
http://myweb.tiscali.co.uk/technologyweb/bellcrank.gif
This is all getting off topic so I think we're beating a dead horse.


Suffice it to say there are reliability issues with the 6000 plus cars with secondaries that work so well with the actuators "purposely" installed upside down. To fix the original design flaws there are those feed up with the reliability of the secondary system so much so that they rip them out.
Not that even a major component of these failures are at the actuator but I submit that it contributes to this reliability issue. In so far that that is true I offer the correction to the weird looking upside down issue for the betterment of the car and it's survival.
I'm now done with this thread.
I must need something at the store. It's nice out and I need to go see if my secondary actuators still work ok. ;)

Re: Secondary Actuators, Upside down or Not
 

I'd suggest ripping them out.....no more troubles...:p

Re: Secondary Actuators, Upside down or Not
 

Yes, I have read several of the threads on that. Still haven't came to a conclusion on that subject.

Re: Secondary Actuators, Upside down or Not
 

For me, it made perfect sense. Less parts to fail and less vac lines to leak. I've never looked back....

Re: Secondary Actuators, Upside down or Not
 

1990 LT5 with Secondaries (Non Kludged)
http://i287.photobucket.com/albums/l...d107332bc7.jpg

1991 LT5 No Secondaries (Kludged)
http://i287.photobucket.com/albums/l...510aaf14f2.jpg

Re: Secondary Actuators, Upside down or Not
 

I prefer "enhanced" over "kludged".:)

Re: Secondary Actuators, Upside down or Not
 

thanks jerry, that sure makes alot of sense

those "little old ladies" so to speak did nice work IMHO

and if it ain't broke, don't fix it. the factory engineers are generally smarter than I am (that's for sure)

but since I was confused, I took them out :-D

I honestly haven't missed them. throttle response is just fine on a stroker LT5 without them. but also DON'T think you'll pick up power, I got about 8 ft lbs of average increase in mid range torque

as marc told me, they don't hurt anything, and work just fine.

and they are there for a reason.

unless you more agressively open up the secondary ports, it's probably not worth the effort to take them out.

but my philosophy is that "parts left out, don't break"

I don't have to worry about linkages, vacuum lines, and doodads under the plenum and I was able to pass the parts on to folks that needed them for a bargain price.