gas pedal vibration

Depends

I can’t tell if my gas pedal has a vibration in it because I usually have it pinned to the floor. 

@Robert M posted:

I can’t tell if my gas pedal has a vibration in it because I usually have it pinned to the floor. 

I really need some cops like you to live near me, Robert. 

Is it from going through the tube in the shroud?  There are these roller shafts.

Eric, I assume you have a Morse cable which is typical of Vintage Spyders?

My cable is mounted to the floor about 6 inches behind the gas pedal. It goes down the center and through the firewall, the under the engine curving up to the upper engine/trans bolt by the starter. No rubber mounts at all.  I also have absolutely no vibration either. I drive barefoot in the summer so I'd definitely feel it.

I also have a solid nosecone mount and a trans strap, so it's not like I have everything rubber-mounted.

Danny yea thats what I thought. I have a vibration coming from something. Any chance you can take a few pictures of your setup? Would like to see how its mounted from the pedal and how you ran it through the cockpit along with how your connector is mounted on the trans to the fuel crossbar for the webers. Mine sounds very similar to how your is, but maybe I'm missing something. This car is great but the the PO was not the best at his adjustments or fixes. Thank brother!

@Robert M posted:

I can’t tell if my gas pedal has a vibration in it because I usually have it pinned to the floor. 

What he failled to say is that he has a peg leg  

@WOLFGANG posted:

Is it from going through the tube in the shroud?  There are these roller shafts.

That's pretty cool. Last year when I installed my Thing shroud, I was shocked at the angle it put on my cable. I lowered my crossbar to the lower point and moved my lever one flat of the hex bar and it was a perfectly straight pull.  The bad news was that I had to lower my coil mount for clearance. 

At least I was able to use one of the "extra" holes I drilled in my new shroud to mount my hard line.

Eric, I finally took those pics you asked for. I leave my Morse cable a little loose at idle. The cable housing expands when hot and if the cable's too tight you'll be idling at 2k. Then I set the full throttle stop at the pedal, so you can't tweak the throttle shafts.

@DannyP thats just how mine is mounted, pretty much the same except the extended block under the throttle connect. The Vibration is still present around 3,700 to 4,200 rpm. Vibrates on the gas pedal is pretty annoying, so far I've played with adjustment at the pedal, and also added some rubber fuel line around the cable where it goes through the body and also turns up from the bottom of the engine and uses a prober clamp to hold in place. No luck. 

Next up is to add a rubber gasket to the mount where the connector bolts to the transaxle to see if vibration is getting transmitted to the cable?

Going to also see how the carbs sync at 3500 to 4000 and see if its off and may be causing the motor to not be pulling correct? I don't feel it in the pants while driving but maybe???

Yeah, if the synch is just slightly off or an idle jet is a tiny bit dirty and restricted you could still feel it at that rev range at light throttle. Does the vibration go away when your foot goes down to the floor?

@DannyP blew out the idle jets, about as much as I can do without fully taking them all apart. Also cleaned out the main jets. Dropped the sync snail on it and one side was 5 other side was 4.75 or so. Don’t think that would make that much of a difference do you? Also re tightened all the bolts to the pedal and the side bolt through the pedal shaft. They we’re right but I sniffed them better. 

car is fine till 3400 rpm then I notice a slight vibration at the pedal, the. From 3700 to about 4500 vibration is pretty bad. From 5000 to 6000 feels ok.

How are your trans mounts? Last year I was having some intermittent issues with my cable shifter and when I checked it out I found that I'd lost the bolt off of one and was just about to lose the bolt off the other side. Tightened 'em back up and the problem went away. 

I'm wondering if loose or broken mounts might cause your problem. 

Just a thought - maybe faulty cooling fan just coincidental with throttle cable change?

@MusbJim posted:

Just a thought - maybe faulty cooling fan just coincidental with throttle cable change?

Good point. Might want to reach in there and see if there's any play from a loosening fan nut or a wallered alternator bearing. 

BTW, did I ever mention the time I thought it would be a good idea to rotate my engine via the fan nut while doing a valve change? 

ok so today I dived in again...

So checked the fan...all is good and spinning correctly. I have a 911 shroud so I cent see the alternator without removing it. My generator light is not on so I don't think its that. 

Checked for and tightened the trans mount bolts. All were there and tight.

Cleaned out the idle jets and mains again, snail sync is pretty even at 5 after warm and at idle on both weber 44's. Also just checking what are people with bigger motors (2276 and bigger) for there idle jets and mains???

Took it out for a drive and the vibration get better, but its still there in the pedal. Around 4000 to 4500 it the worst. Car feels fine, with just a bit of stumble when I hit the gas, she lays a bit flat for a split second. Then takes off and climbs to 6500 to 7000 no problem. Think I could have a spark issue...or maybe something in the carb and its not pulling air correct??

Accepting more ideas if anyone has them....

Could it be something as basic as a failing mount?  I had different symptoms when my transaxle nosecone mount started to fail, but maybe...?

Eric, have you done a high speed linkage synch? Have someone use the gas pedal to hold the engine at your problem rpm, and use the synch meter to see what your air is like side-to-side there. Idle synch is important but obviously not your problem.

If the synch is dead on, I'd say it's time to take the engine apart and have the rotating parts balanced.

Or install a new set of plugs.  Maybe some plug wires, disti cap and rotor, too.

I seriously doubt it's ignition at a certain small rpm range, but above and below are fine. But then again, stranger things have happened!

@DannyP Going to do the high speed sync today and see where she is at. Did it at 3000 rpm last week and didn't notice anything. Also want someone under the car on the lift to see the belt, thinking maybe it may be slipping? 

Already have the new wires, cap and rotor on the way from before. Checked all plugs and they are pretty good, no oil and clean. I'll also be doing the timing to make sure its not out. 

Such a strange little thing....