Author Topic: Throttle Linkage Dilemma  (Read 1431 times)

Mike Hughes

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Re: Throttle Linkage Dilemma
« Reply #25 on: April 12, 2019, 20:49:56 »
Regarding the gas pedal arm hitting the hole in the firewall:  Loosen the gas pedal shaft fixing bolt on the throttle shaft lever and adjust the angle of the pedal shaft.  The slot in the lever that the bolt tightens to is elongated for adjustment.

In one of the photos mrfatboy posted you can clearly see the elongated slot.  You can see his pedal arm is adjusted such that the pinch bolt is at or near the lower extreme of the elongated slot.  It appears that your pinch bolt is at the upper extreme of the elongated slot.
« Last Edit: April 13, 2019, 00:15:17 by Mike Hughes »
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jzearfoss

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Re: Throttle Linkage Dilemma
« Reply #26 on: April 13, 2019, 17:57:21 »
To mrfatboy - Thanks for the photos.  Should be helpful as future reference for others as they tackle their rebuilds.  For me they confirm that I have the mounting hardware correct but I am still unsuccessful in solving my geometry problem. 

to Mike Hughes - I have done as you suggest with the bolt that holds the regulating shaft to the pedal lever.  It buys me a little but not enough to give me what I need at the pivot where the regulating rod (push rod) connects. 
1968 280 SL (AT)
2000 BMW Z3
1962 Pontiac Grand Prix
1951 Studebaker Commander
1937 Plymouth.

mrfatboy

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Re: Throttle Linkage Dilemma
« Reply #27 on: April 13, 2019, 18:07:16 »
At this point I would suggest to disconnect the linkage (attached to pedal) on the left side of the firewall.

Connect the horizontal rod to the pivot bracket on the right side of the engine.

From there back track which might help you find the problem. It will help you find where things like to be.
« Last Edit: April 14, 2019, 01:22:08 by mrfatboy »
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Mike Hughes

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Re: Throttle Linkage Dilemma
« Reply #28 on: April 14, 2019, 00:50:44 »
I would agree.  Just remove the pinch bolt for the pedal arm.  If you still can't get the pivot arm to drop down enough to attach the push rod at both ends, then work back along the throttle shaft that crosses behind the engine to see what is hanging it up.  I'm hoping that it is just the microswitch on the firewall and that flipping over the bracket and reinstalling it so that the switch sits a little lower does the trick. 

I'm also hoping that it is not that somehow the pivot arm was stepped on or otherwise bent, twisted or otherwise realigned with the throttle shaft while it was off the car.  That's the sort of thing one wouldn't notice until later - like now!  The only reason why I even bring that up as a possibility is that it looks in your one photo like the arm with the adjustment screw that contacts the microswitch may have been bent already and I would assume that significant force would have been involved for that to have happened.

Can anyone comment on how that pivot arm is attached to the cross throttle shaft?  Is it tack welded or brazed, or is it pinned?
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jzearfoss

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Re: Throttle Linkage Dilemma
« Reply #29 on: April 14, 2019, 21:41:31 »
Here we go - day 4.

Thanks Mike for the input. Every connection has been apart and reassembled several times now, in both directions - from the pedal lever forward - from the regulating rod back. No improvement.  And lowering the micro-switch bracket is ineffectual.

Mike - regarding your idea that the regulating shaft or regulating rod or the lever arm with the slotted hole may have been bent, twisted or otherwise realigned while off the car.  I am inclined to come to the conclusion that the evidence does not support that theory.  The regulating shaft is solid steel (dia.=5/8"), regulating rod is  solid steel (dis. =1/2") and the slotted hole lever is solid steel (1/8" thick = 11 ga.). Is was stored in a typical 64 qt. plastic tub on a shelf and did not come off the shelf until I started the reassembly. 

The regulating rod and the slotted hole lever are welded on the regulating shaft so there was no possibility of rotational slippage.  Yes the micro-switch lever arm is twisted a bit in a lateral direction but it was like that before the regulating shaft was removed.

New question:
Can anyone tell me the distance between the back of the valve cover and the fire wall?

It must be enough so that the valve cover can be removed while the engine is still in the car.  It would have to be far enough forward to clear the welded bracket that holds the hood release mechanism.  I can not remove my valve cover the way the engine currently sits in the car.  It will not clear the welded bracket.

See what I am getting at here.  My guess (at this point anyway) is that the engine is not far enough forward for the regulating rod to fit correctly with the pivot on the engine block.

If I put the car up on jack stands and have the wheels clear the floor and I unbolt the two bar leaf springs that connect the crossmember to the front of the frame then the whole crossmember/front suspension assembly is free to swing (forward) as it hangs from the flexible mountings that bolt the crossmember to the frame.  Every bushing and flexible mount has been replaced with new rubber so I am sure things have tightened up a bit.

There are other connections points that need to be addressed as well: the steering idler, the steering damper, as well at the pitman arm, but I am willing to start messing around with this possibility.

Any thoughts or suggestions out there? jz
1968 280 SL (AT)
2000 BMW Z3
1962 Pontiac Grand Prix
1951 Studebaker Commander
1937 Plymouth.

mrfatboy

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Re: Throttle Linkage Dilemma
« Reply #30 on: April 14, 2019, 22:39:51 »
Here ya go.  Measurements are close.  The green measurement would be from the top plane and back of the valve cover across to the bracket on the firewall.
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jzearfoss

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Re: Throttle Linkage Dilemma
« Reply #31 on: April 14, 2019, 22:56:14 »
Hey mrfatboy - if you were to remove you valve cover would you then be able to remove the regulating shaft from off of the firewall?
1968 280 SL (AT)
2000 BMW Z3
1962 Pontiac Grand Prix
1951 Studebaker Commander
1937 Plymouth.

mrfatboy

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Re: Throttle Linkage Dilemma
« Reply #32 on: April 14, 2019, 22:58:35 »
Yes.  I can even remove it with the valve cover on.  It would be a tight squeeze though. I probably would end up pulling it through as not to scratch paint.
« Last Edit: April 14, 2019, 23:33:05 by mrfatboy »
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Pawel66

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Re: Throttle Linkage Dilemma
« Reply #33 on: April 15, 2019, 00:33:24 »
jzearfoss, if you cannot remove the valve cover because it cannot clear the hood lock assembly - it often means your transmission mount rests too low. In the regular usage of the car it is an indicator that you should look at/replace your rubber mount in the back there.

It does not have to mean your engine is somehow too far back.
Pawel

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jzearfoss

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Re: Throttle Linkage Dilemma
« Reply #34 on: April 15, 2019, 02:08:47 »
To Pawell66 - I have new rubber there too. I have the tranny jacked up on a wheeled jack to the the level it would sit when installed and connected to the driveshaft. The bit of tilt  (and resulting angling back of the valve cover) that might have resulted from the back of the tranny being to low is a non-issue.  Good catch though. jz
1968 280 SL (AT)
2000 BMW Z3
1962 Pontiac Grand Prix
1951 Studebaker Commander
1937 Plymouth.

Pawel66

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Re: Throttle Linkage Dilemma
« Reply #35 on: April 15, 2019, 07:23:42 »
I am keeping my fingers crossed you find solution to this topic quickly.

I wish i could be of more help.

I am not experienced enough obviously to figure out how come your engine may be too far back.

But every time I go through pictures, i have an impression that the lever attached to cross shaft on the passenger side is bent downwards in your case less then e.g. mine or the other ones in the pictures.
« Last Edit: April 15, 2019, 07:30:49 by Pawel66 »
Pawel

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mrfatboy

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Re: Throttle Linkage Dilemma
« Reply #36 on: April 15, 2019, 12:20:21 »
Can you post a picture at the same angle I did in post #30?  What are your measurements?   Maybe even more pictures might help us see what is going on.
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Pawel66

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Re: Throttle Linkage Dilemma
« Reply #37 on: April 15, 2019, 12:55:47 »
You have the pictures from mrfatboy and from me of that lever at 90deg angle (more or less). The lever is "upright" along the firewall. Is it the same in your car? If not - is it caused by the gas pedal lever lack of clearance in the firewall hole or something else?

If it is the lack of clearance on the hole - I am back to square 1 with no ideas.
Pawel

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jzearfoss

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Re: Throttle Linkage Dilemma
« Reply #38 on: April 17, 2019, 17:21:10 »
Been out of town for a couple of days.  Back now so will snap a few photos as requested and get them posted later today.
1968 280 SL (AT)
2000 BMW Z3
1962 Pontiac Grand Prix
1951 Studebaker Commander
1937 Plymouth.

jzearfoss

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Re: Throttle Linkage Dilemma
« Reply #39 on: April 18, 2019, 17:33:49 »
Here are 4 photos of the regulating shaft that may clear up what is lacking in previous posts:

Photo1 -this shows the regulating shaft on the passenger side and its clearance from the firewall when it is NOT connected to the pedal lever and bolt  #51 is removed. The clearance from the firewall is approx. 3-5 mm. The gas pedal and pedal lever are in the position of being at full idle and the result is that the threaded hole where bolt #51 is supposed to attach to the pedal lever is in such a position that the bolt can not be secured.

Photo2 - this shows the regulating shaft on the drivers side where it is would connect to the pedal lever and as noted above - bolt #51 can not be secured to the pedal lever.

Photo3 -  this shows the regulating shaft on the passenger side and its clearance from the firewall when it connects to the pedal lever and bolt  #51 is secured at the top of the slotted opening  .The clearance from the firewall is approx. 30mm. When in this position the gas pedal and pedal lever are in the position of being at full idle and bolt #51 can be connected to the pedal lever. 

Photo4 - this shows the regulating shaft on the drivers side where it connects to the pedal lever and as noted above - bolt #51 is secured at the top of the slotted opening.

Hope these help. jz

1968 280 SL (AT)
2000 BMW Z3
1962 Pontiac Grand Prix
1951 Studebaker Commander
1937 Plymouth.

Pawel66

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Re: Throttle Linkage Dilemma
« Reply #40 on: April 18, 2019, 19:00:29 »
And in the "almost full idle" position the gas pedal lever gets stuck against the upper edge of the hole in the firewall and will not go to "full idle position" .

Well, obviously the brackets holding the cross-shaft to firewall, #8 and 9, are swapped, but this is the mistake of the drawing, I guess.

I also assume that you did not install the gas pedal lever upside down - that would be crazy as you would have it sticking up inside, in the footwell.

I also assume you tried to see if you can screw the driver's side bracket a bit lower, as it may have the screw holes a bit bigger than the screw diameter and I assume it is not the head of the upper bolt holding this bracket high. So there is no way to tighten this bracket lower.

Then I cannot think of anything else than one of the levers is bent i n a bit wrong way or the lever that is fixed to the shaft turned a bit on it.

I would probably try very unprofessionally to: try to file the holes in the driver's side bracket to tighten it lower or try to shimm it if it helps or bend one of the levers back in place.

I am very curious what is the correct solution here.
Pawel

280SL 1970 automatic 180G Silver
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W121 190SL
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mrfatboy

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Re: Throttle Linkage Dilemma
« Reply #41 on: April 18, 2019, 19:17:34 »
His engine is definitely much closer to the firewall than in my pictures. I would not file or grind anything just yet. It's got to be something we are just not seeing.
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Mike Hughes

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Re: Throttle Linkage Dilemma
« Reply #42 on: April 20, 2019, 18:41:41 »
I agree, your engine is WAY to close to the firewall.  Are the holes slotted where the trans mount is secured on either side of the of the trans tunnel?  Between that, the trans mount and motor mounts themselves and the fixing points of the straps up front between the cross member and the uni-body frame there may be some possibility of fore and aft adjustment of the engine within the engine compartment.  Get it as far away from the firewall as possible (taking care not to get the fan too close to the radiator!)  It may be a bit tedious to try to do alone - do I hear "garage party?"
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jzearfoss

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Re: Throttle Linkage Dilemma
« Reply #43 on: April 21, 2019, 20:37:21 »
Sunday morning - second cup of coffee. I'm ready to go.

To Mike and mrfatboy - I have been able to gain some separation of the engine from the firewall. I can now remove the regulating shaft without much trouble.  It is now removed from the car and I am going to set out on a hypothesis that I have at this time.

If you look at my Photo1 in my previous post you will notice that the first bend in the lever arm as it extends off of the regulating shaft does not seem to have as much articulation as I see in the mrfatboy second photo in Reply #23 which looks to have been taken at much the same perspective as my Photo1.

I know in my previous posts I have been pretty adamant that the lever arm off of the regulating shaft could not have been bent given the material it is made out of and the diameter of the lever arm, but I am willing to concede that it does not look like what I see in mrfatboy's photo. 

So I am now going to examine the possibility of altering the geometry of the lever arm.  Here are 3 photos of the regulating shaft and the lever arm and an explanation of what I am seeing.

Photo5 - this shows the regulating shaft removed from the car and laid out on a piece of white cardboard and the arrow is pointing to the bend in the lever arm that I am focusing on.

Photo6 - in this shot I have laid the lever arm on the cardboard and have traced the outline of the lever arm onto the cardboard

Photo7 - here I have extended centerline projections of the two parts of the lever arm that make up the bend I am looking at and I have measured the angle of the bend and got 13 degrees as a result.

I know this is asking a bit much - but -do any of you have any idea of what this angle is on the lever arm on your car.  I have searched around and can not find anything that even resembles a specification for that bend in the lever arm.

I am  fairly well convinced that I can achieve the geometry needed for the throttle linkage to work correctly by modifying that angle.  It will take a little heat and some carefully applied pressure but I think it can be done.  If I do not get any response as to what the angle might/should be then I will proceed incrementally and do a bunch test fitting and kind of sneak up on the angle that will work for me.

Sun is out and shining here in Libby today so I will be out for a bike ride and let the shop stay quiet for a while.
1968 280 SL (AT)
2000 BMW Z3
1962 Pontiac Grand Prix
1951 Studebaker Commander
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66andBlue

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Re: Throttle Linkage Dilemma
« Reply #44 on: April 21, 2019, 21:28:07 »
Sorry, I don't know what the angle is but to me your lever looks correct.
Attached are photos of the part in two different cars. To me they look like yours, but you be the judge.
Alfred
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waltklatt

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Re: Throttle Linkage Dilemma
« Reply #45 on: April 22, 2019, 19:54:23 »
JZ,
See attached picture.  Took your picture and see the obvious issue with your linkage rod.
Do this fix and it should be ok again.
Walter

Pawel66

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Re: Throttle Linkage Dilemma
« Reply #46 on: April 22, 2019, 20:23:50 »
I think Walter has it. The piece between the two "elbows" is straight on other pictures. Yours is bent. Straightening it in this place right below the upper elbow would move the linkage rod way aft.
Pawel

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jzearfoss

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Re: Throttle Linkage Dilemma
« Reply #47 on: April 23, 2019, 21:32:54 »
Well it seems as if an answer has finally surfaced.  As pointed out in the previous 2 posts from Walt and Pawel66 the bent center section of the lever arm looked to be a likely source of my faulty linkage geometry. 

I placed the bent section on my bench vice anvil surface and using a 3 lb. sledge was able to straighten it out and gained about 20 mm of travel.  That, along with the little bit of gain I got by being able to get the engine to move forward (another 20 mm) is enough  for me to have the linkage work without hanging up on anything.

Thanks to all who choose to wrangle with this dilemma of mine, reading through the posts, and offering up photos to use for comparison.  Hope I can be of some assistance to others in the future as my breadth of experience expands.  Still have a ways to go before I get this thing all back together but at least I can now move on with my restoration.
1968 280 SL (AT)
2000 BMW Z3
1962 Pontiac Grand Prix
1951 Studebaker Commander
1937 Plymouth.

Benz Dr.

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Re: Throttle Linkage Dilemma
« Reply #48 on: April 23, 2019, 22:19:04 »
Main question for me would be what bent your throttle linkage? I would imagine that it happened during installation or removal of your engine which is why I always remove all of the throttle linkage before I start that job.
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Mike Hughes

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Re: Throttle Linkage Dilemma
« Reply #49 on: April 23, 2019, 23:16:33 »
As soon as I saw your photo #5, I said to myself, "that arm was stepped on or something was dropped on it while it was laying on the floor or on a bench!"

The best thing is that the fix was realtively simple, and you can move forward with your project.  Bravo!
« Last Edit: April 23, 2019, 23:30:28 by Mike Hughes »
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