Gas Pedal Vibrations Fix Idea

[richk]

Below is a picture that I took of the gas pedal assembly on my H3. I have been thinking about a way to isolate the pedal mechanism from the firewall in an attempt to eliminate the pass-thru of engine vibration (which is bugging me! and has been discussed in previous posts). What I am asking for is input (especially from you H3 builders/techs). Here is my idea:

1. Disconnect the electrical cable from the pedal assembly.
2. Remove the pedal assembly from the firewall.
a. From my photo it appears to be held on with 3 screws, with nuts on the inside of the cab. I am a little concerned that the bolt will stay in the firewall. Can anyone confirm if these are welded or otherwise secured? It would be terrible if removing the nuts caused the bolts to become loose and perhaps fall out. I crawled under the H3 and the backside of the bolts appear to be covered with a heavy felt.
3. Once the entire pedal assembly is removed I am thinking of laying it down onto a piece of heavy rubber and tracing around the outside.
4. Cut out the pattern from the piece of rubber (or heavy padding/foam I am not sure what would work better).
5. Drill out the 3 holes for the bolts.
6. Re-assemble with the rubber between the firewall and the pedal assembly.

Any thoughts or ideas would be appreciated. In particular, are the 3 bolts welded in place?

Thanks,
Richard


...

[richk]

Below is a picture that I took of the gas pedal assembly on my H3. I have been thinking about a way to isolate the pedal mechanism from the firewall in an attempt to eliminate the pass-thru of engine vibration (which is bugging me! and has been discussed in previous posts). What I am asking for is input (especially from you H3 builders/techs). Here is my idea:

1. Disconnect the electrical cable from the pedal assembly.
2. Remove the pedal assembly from the firewall.
a. From my photo it appears to be held on with 3 screws, with nuts on the inside of the cab. I am a little concerned that the bolt will stay in the firewall. Can anyone confirm if these are welded or otherwise secured? It would be terrible if removing the nuts caused the bolts to become loose and perhaps fall out. I crawled under the H3 and the backside of the bolts appear to be covered with a heavy felt.
3. Once the entire pedal assembly is removed I am thinking of laying it down onto a piece of heavy rubber and tracing around the outside.
4. Cut out the pattern from the piece of rubber (or heavy padding/foam I am not sure what would work better).
5. Drill out the 3 holes for the bolts.
6. Re-assemble with the rubber between the firewall and the pedal assembly.

Any thoughts or ideas would be appreciated. In particular, are the 3 bolts welded in place?

Thanks,
Richard


...

[f5fstop]

I'll look at the naked H3 we have in the back; however, my guess would be there are weld studs to make service easier. But can't confirm till I look.
Your idea might work. I have no vibration in my H3,

[f5fstop]

Confirmed; those are weld studs, you can remove your nuts safely.

[PARAGON]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by f5fstop:
Confirmed; those are weld studs, you can remove your nuts safely. </div></BLOCKQUOTE>And then you would have geldings.

[bparker]

Try using a double layer or even tripple layer of Dynamat as a gasket.

Dynatmat is used in the car audio industry as a severe sounds and vibration dampener for loud audio systems.

You can get it at any Best Buy or Circuit City near you.

[richk]

Great, glad to hear the studs are welded in place. I will try the Dynamat. I think I'll be tackling this project this weekend. I will let you know the result.

It's weird that some of you are not reporting this same issue. I might consider renting another H3 at some point in the future to see if any of my outstanding issues can be duplicated.

The dealer is not much help. They aren't really interested in what they consider little issues like this. The attitude is kind of like "let me test drive it", then "it seems fine to me". Yeah big surprise, they are driving with the windows down, radio on, etc. and really aren't looking for "feeling" type stuff that I deal with on my daily driving.

[bparker]

For the record mine does it too, but it doesnt bother me... But if I can help you guys fix it even better..

=)

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by richk:
It's weird that some of you are not reporting this same issue. I might consider renting another H3 at some point in the future to see if any of my outstanding issues can be duplicated. </div></BLOCKQUOTE>

[humv]

I have the same thing with mine. It is not that bad but does bother me at times.I thought I was being picky and was going to take it to the dealer but you confirmed what they would say...WE don't feel anything must be you!I said something to the wife if she noticed anything and she said no.Then again the engine could fall out and be draging behind and she would say the same thing.

[richk]

It really bugs me when I drive my wife's Toyota Sequoia because her pedal is completely "dead". It doesn't transmit anything to your foot. GM are you listening? You need to fix this.

[Marc H3]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by f5fstop:
... I have no vibration in my H3, </div></BLOCKQUOTE><span class="ev_code_BLUE">I also feel NO vibrations there</span>

[ChevyHighPerformance]

If you use rubber or dynamat, perhaps you can double nut the pedal to prevent it from wiggleing loose (if these nuts aren't locknuts already). Also, be careful with the sensor on the gas pedal, if it gets messed up you'll be in reduced power mode.

[f5fstop]

No vibration here. I was looking at the pedal assembly today, it is pretty robust.

[richk]

How would the sensor get messed up? Just disconnecting and reconnecting shouldn't cause any problems.

Robust? The electronics might be advanced, perhaps an optical sensor like a mouse, but the pedal support and pedal itself are made of plastic.

[PARAGON]

If you are getting some type of vibration at the pedal, I personally doubt attempting to isolate the mouting in any way is going to achieve great success. First, the pedal has to remain in a fairly rigid mount. To do this you have to maintain contact with the studs, no matter what. Even if you place dampening material between the back of the assembly and the firewall the studs will still transfer whatever vibrations might be present. Second, when you place it against something less rigid, it will have a tendancy to carry the vibration more.

IMO, I think you need to find the source of the vibration. Granted a 5cyl does not run as smoothly as an 8cyl, but it is far reach to accept that engine vibration (by design) easily makes it to the accelerator. Since it is an electronic it is not transfering it through a cable, the motor mounts and the body mounts would further isolate the firewall from direct vibrations. It could be resonation there but one would assume that would be rather low frequency and you would "feel" it in other places.

Try to think of the cause. Does it happen more at idle or at average RPMs? If you rest your other foot on the brake pedal can you feel it there? Does it vibrate at the same rate that you hear the exhaust note?

I would just fear that you might end up with a worse situation without exploring possible causes for it.

[f5fstop]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by richk:
How would the sensor get messed up? Just disconnecting and reconnecting shouldn't cause any problems.

Robust? The electronics might be advanced, perhaps an optical sensor like a mouse, but the pedal support and pedal itself are made of plastic. </div></BLOCKQUOTE>

For a pedal assembly with a sensor, it is robust; especially when compared against the ones put on Cobalts, Saturns, etc. I guess if you have nothing to compare with, you might not understand what I'm talking about.
I never thought anyone would mess it up removing it.

I also have to agree with Paragon's statement above. To cure a problem, go after the root cause.

[ChevyHighPerformance]

I just mentioned about the pedal and the reduced power mode because some trailblazers, envoys, and silverados are having a problem.

[richk]

Good input. Yes I also feel the same vibrations thru the brake pedal but this doesn't really bother me because my foot is not on the brake for any long period of driving time and there's no vibration at a stop light.

Another reason I want to try and isolate the pedal is because of the knocking that is also being transmited thru the pedal. This is a different problem that has been discussed in other threads. In summary, I get a knocking noise and feeling sometimes. It's weird because it doesn't happen all the time. For example on short trips in the morning or on my way home. When it starts knocking you can hear it with your ears, feel the knocking in all the pedals and even the steering wheel. I brought it in to the dealer twice and they claim they cannot reproduce it or hear anything.

Every time it has happened and I have had a passenger with me I ask them "do you hear that knocking noise", and everyone says yes. I now have a better handle on what it takes to make the noise louder when it's occuring. The dealer has offered to have a tech drive with me at any time. However it has been 2 weeks since that offer and I have only had the knocking issue occur on weekends or when I didn't have time to spend at the dealership.

Btw, if you review the knocking thread, other H3 owners responded that they had the same issue and some of them even described it better than me. So my knocking/vibration issue is not limited to my particular H3. Sometimes I feel quite frustrated because these are little stupid things but they are driving me nuts, like a splinter in my finger. When my H3 starts making the knocking noise and thumping against my foot I just want to drive it off the overpass. These issues are ruining what should be a great experience with my new Hummer. (not to mention the wind noise from the marker lights).

[PARAGON]

The knocking noise can be a hard one. On the early H2s (mine did it) the driver's side inner and outer fender was popping. To solve the problem they would take a round-nose punch and knock dents/dimples inside the inner fender. It obviously took up some slack on the fender and kept it from flexing.

On my truck I actually thought it was a front suspension issue and it felt like someone was hitting the bottom of the floorboard with a hammer. It was the fender flexing. Dimpled it and it hasn't done it since.

Keep taking it in and/or try another dealer. It's not "little" stuff. I can assure GM wants it fixed as much as you do because they don't want to have future potential customers (you and your passengers) thinking it's a rattle trap. Problem is that some service technicians don't share this same outlook and you have to hand them the problem for them to fix it.

[richk]

Yeah I have already had some passenger comments like "what do you expect from an american car". The roof marker lights have been so loud sometimes that several passengers starting laughing. Comments were not pleasant, i.e. you paid $35k for this?, etc. And I have no way to defend GM except to pass it off as issues with a first year vehicle. My comment would be something like "well I'm sure GM will fix these kind of things in future revisions". It's just sad that we early supporters/purchasers have to deal with this.