A couple of issues from track this weekend - vibration and no start

[ChipG]

Hi all,

Perhaps a more interesting set of questions than wheel powder coat colors I went to my 4th track event this weekend at NCM and encountered a couple of issues - interested in thoughts on causes.

First - vibration issue.
Once the car was warmed up, in high-g corners where the front right tire was heavily loaded (sinkhole at NCM for those that know it) I was getting a significant pulsing vibration from the front. It was maybe 10 hz and could be felt and heard by me and by my passenger. It was more intense with more load. I got some on right hand turns as well but not as strong. I removed the wheel to check and found no indication of rubbing or interference, and the hub/bearings didn't seem loose (with wheel in the air, no "give" when pushing/pulling the wheel from any angle). I changed to different wheels and tires for day 2, and got the same vibration but milder during lap 2 or 3 of a session then it went away, so it seems not to be the wheel/tire itself. My best guess at this point is still possible hub/bearing issue but as I said, no movement and when rotating the wheel there was no grinding or noise, just normal smooth rotation. I'm a bit baffled.

Second - hot no-start.
This has happened once before at a track day, never on the street. Not long after a session when the car is hot and hasn't cooled down yet, I tried to start and there was simply nothing. No attempt to start, no clicking, just every starter button press was as if I had just gone into accessory on again. It didn't toggle back and forth between accessory on and off, just went to accessory on again and no attempt to start. Not consistent, in both cases where this occurred, after several tries it simply started and then ran as normal. Any thoughts? Feels like an electrical or switch/sensor issue somehow - like when it's hot it doesn't recognize the clutch is in or some ground or something isn't connecting well. Anybody had this?

Any and all input appreciated, thanks.

Chip

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[pilotgore]

Hi all,

Perhaps a more interesting set of questions than wheel powder coat colors I went to my 4th track event this weekend at NCM and encountered a couple of issues - interested in thoughts on causes.

First - vibration issue.
Once the car was warmed up, in high-g corners where the front right tire was heavily loaded (sinkhole at NCM for those that know it) I was getting a significant pulsing vibration from the front. It was maybe 10 hz and could be felt and heard by me and by my passenger. It was more intense with more load. I got some on right hand turns as well but not as strong. I removed the wheel to check and found no indication of rubbing or interference, and the hub/bearings didn't seem loose (with wheel in the air, no "give" when pushing/pulling the wheel from any angle). I changed to different wheels and tires for day 2, and got the same vibration but milder during lap 2 or 3 of a session then it went away, so it seems not to be the wheel/tire itself. My best guess at this point is still possible hub/bearing issue but as I said, no movement and when rotating the wheel there was no grinding or noise, just normal smooth rotation. I'm a bit baffled.

Second - hot no-start.
This has happened once before at a track day, never on the street. Not long after a session when the car is hot and hasn't cooled down yet, I tried to start and there was simply nothing. No attempt to start, no clicking, just every starter button press was as if I had just gone into accessory on again. It didn't toggle back and forth between accessory on and off, just went to accessory on again and no attempt to start. Not consistent, in both cases where this occurred, after several tries it simply started and then ran as normal. Any thoughts? Feels like an electrical or switch/sensor issue somehow - like when it's hot it doesn't recognize the clutch is in or some ground or something isn't connecting well. Anybody had this?

Any and all input appreciated, thanks.

Chip

Regarding the start issue… sounds identical to what myself and @meterman went through when he and I both lost (or were in the process of) losing our starters.

 

[ChipG]

That's disturbing. How many miles when that happened to you two? I've got just over 12k miles, seems super early for a starter to crap out. Was it the solenoid?

 

[pilotgore]

That's disturbing. How many miles when that happened to you two? I've got just over 12k miles, seems super early for a starter to crap out. Was it the solenoid?

6,200 for me. Starters are a known weak point of the s550 platform. Ford performance offers an upgrade in case yours does go out.

For maybe 1000 miles prior to complete failure, I have 4-5 times where the car wouldn’t start on the first or second button push. The good news is… you can always push the car and pop the clutch I went through a whole track weekend like that in august.

 

[ChipG]

6,200 for me. Starters are a known weak point of the s550 platform. Ford performance offers an upgrade in case yours does go out.

For maybe 1000 miles prior to complete failure, I have 4-5 times where the car wouldn’t start on the first or second button push. The good news is… you can always push the car and pop the clutch I went through a whole track weekend like that in august.

Yike, I hope not to get to that point. Any more recurrence and it's dealer visit time.

 

[pilotgore]

Yike, I hope not to get to that point. Any more recurrence and it's dealer visit time.

Best of luck!

 

[matthewr87]

Regarding your turning vibration, it is hard to discern from your description, but I have had similar things happen during my track days following sharp high G turns. It usually goes away after a few laps so in my case I think I just pick up some rubber on the tire and that temporary uneven surface results in the vibration. Again, not sure if this is a plausible explanation for your issue but the first time it happened it scared the crap out of me. I thought I lost a tire.

 

[kluke15]

im curious if the starter gets overheated due to the stock headers on the 350 vs the gt exhast and craps out quick. i had a clutch switch issue preventing my car from turning over but it would always tell me the clutch needed to be depressed. i never had it give me zero info and not start.

 

[ChipG]

Regarding your turning vibration, it is hard to discern from your description, but I have had similar things happen during my track days following sharp high G turns. It usually goes away after a few laps so in my case I think I just pick up some rubber on the tire and that temporary uneven surface results in the vibration. Again, not sure if this is a plausible explanation for your issue but the first time it happened it scared the crap out of me. I thought I lost a tire.

First thought was "OPR" (other people's rubber) but the vibration was consistent, repeatable, and load dependent which makes me skeptical that that's it.

 

[WCRookie99]

That's disturbing. How many miles when that happened to you two? I've got just over 12k miles, seems super early for a starter to crap out. Was it the solenoid?

My guess solenoid, on my Boss R it went out as well. It's directly mounted to the starter and gets fried.

As for the vibration, try front sway bar mounts. If not double check the hubs and all suspension points.

 

[honeybadger]

First thought was "OPR" (other people's rubber) but the vibration was consistent, repeatable, and load dependent which makes me skeptical that that's it.

I had a similar issue - turned out to be my oil pan rubbing on steering rack. Check your motor mounts for loose bolts. If you can, get some eyes on the pan where it's near the steering rack

 

[ChipG]

So, I had my car checked out yesterday regarding the vibration. No rubbing/witness marks anywhere (including oil pan and steering rack), hubs/bearings tight, motor mounts tight, no play anywhere in the suspension, so this is a real head-scratcher. The guy at my shop could only posit that perhaps there's tire hop due to being under-sprung, but thought that is a long shot as well given that suspension and tires are more or less OEM spec, so that kind of hop shouldn't happen out of the box. Only deviation from OEM spec was alignment (-3.5* camber up front at the time) and two different non-OEM wheel/tire combos: day 1 305/30 SC2s (R-spec) on Apex 11.5" wheels, day 2 was 315/30 PS4S on Signature 11.5" wheels.

Any reason why a lighter wheel and wider tires (in one case stickier, in one case less sticky than OEM) with negative camber might result in wheel hop under heavy load with OEM springs? I'm kinda grasping at straws here. If it helps my app shows I was pushing 1.1 - 1.3 Gs steady through the corner where this occurred most intensely.

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