Sticky clutch engagement in 1st gear - worn out clutch?

Jonathan O'Hara

Active Member
Hello all,

When I'm in first gear, unless I'm very gradual and smooth in letting off the clutch pedal and applying the throttle, I get some borderline whiplash jerkiness in acceleration. I mean the car will surge forward for a fraction of a second, and then ease off, then surge again and repeat and repeat.

This problem became worse when I upgraded by SC to a TVS1320, and the problem then also spread to second gear (though much less severely than in first gear).

I only took the donor on a pretty short test drive, but I didn't experience this problem. Possibly because the heavier car prevented the same degree of acceleration as is possible with the Goblin?

My initial guess is that this may be a symptom of a worn out clutch? The donor had 200k miles and I have no idea when the clutch was last (if ever) changed. Any other tests anyone might suggest to confirm whether its a clutch issue?

Thanks for any input!
 

George

Goblin Guru
The problem is the programing. The throttle is most likely set at 100%. I changed my to 50% upto about 2500rpm
It can be set lower. Stock setting is some times only 10% off idle

Brad
 

ctuinstra

Goblin Guru
I believe Brad is talking about the Torque Management. This is a graphical representation of what I found ZZP is doing to the tune to make the car "feel" more responsive, which can work in a heavier car such as the donor but is amplified in a lighter vehicle such as the Goblin. We noticed from day one driving our donor that the throttle was extremely touchy. In the Goblin, if you hit a small bump and you bumped the throttle some, it would lurch forward which causes you to fall back thus pulling your foot from the throttle, which causes it to fall, which causes you to fall forward and hit the throttle again and the cycle repeats. You end up in a horrible cycle of throttle on/off that can only be fixed by getting off the throttle completely or just mashing it to the floor.

Below is is the stock TQ Management. Notice that it pretty flat through most of the "normal" driving range and only ramps up when demanding lots of torque. This helps to deliver a manageable driving experience. The TUNED below is what ZZP did to our map. Notice that there isn't much in the low end and pretty quickly goes to all or nothing. This give great throttle response! But too much and makes it hard to drive. We have since learned to drive it smooth and have blended the two graphs for our tune.


John, what you explained is exactly what we have experienced. It just goes to show, they can be very responsive and you have to control your foot or you can tune it down some. We are looking into putting a much stiffer spring on the throttle this winter, the pedal is way too soft. We ride with the side of our foot rubbing the tunnel to smooth out our foot.

B.T.W. These charts make it look like there is no power down below, that is not the case, it just reduces the spark timing to smooth the throttle. Stab the gas on your modern car while in park and I'll bet it will barely rise in RPM unless you just hold it there. That's this controlling it.

STOCK
8877
8878



ZZP TUNED
8879

8880
 

Jonathan O'Hara

Active Member
I believe Brad is talking about the Torque Management. This is a graphical representation of what I found ZZP is doing to the tune to make the car "feel" more responsive, which can work in a heavier car such as the donor but is amplified in a lighter vehicle such as the Goblin. We noticed from day one driving our donor that the throttle was extremely touchy. In the Goblin, if you hit a small bump and you bumped the throttle some, it would lurch forward which causes you to fall back thus pulling your foot from the throttle, which causes it to fall, which causes you to fall forward and hit the throttle again and the cycle repeats. You end up in a horrible cycle of throttle on/off that can only be fixed by getting off the throttle completely or just mashing it to the floor.

Below is is the stock TQ Management. Notice that it pretty flat through most of the "normal" driving range and only ramps up when demanding lots of torque. This helps to deliver a manageable driving experience. The TUNED below is what ZZP did to our map. Notice that there isn't much in the low end and pretty quickly goes to all or nothing. This give great throttle response! But too much and makes it hard to drive. We have since learned to drive it smooth and have blended the two graphs for our tune.


John, what you explained is exactly what we have experienced. It just goes to show, they can be very responsive and you have to control your foot or you can tune it down some. We are looking into putting a much stiffer spring on the throttle this winter, the pedal is way too soft. We ride with the side of our foot rubbing the tunnel to smooth out our foot.

B.T.W. These charts make it look like there is no power down below, that is not the case, it just reduces the spark timing to smooth the throttle. Stab the gas on your modern car while in park and I'll bet it will barely rise in RPM unless you just hold it there. That's this controlling it.
Thanks guys! This sounds very likely to be my problem, especially since when I upgraded to SCs, I installed 60# injectors and took the opportunity to do some other tuning, including removing torque management ... I'll do a little HP tuning and put some of that back!
 

Jonathan O'Hara

Active Member
Just confirming, torque management was definitely my problem, though I hadn't actually modified the table ctuinstra referred to. In my tuning wisdom (or lack thereof), I'd actually zeroed out the "Retard vs % Torque Reduction" Table. I returned it to stock, and the jerking problem is now gone.

I'm still going to play around with torque management to make sure I'm getting the most out of Goblin!
 

DCMoney

Goblin Guru
I'm getting no where on the torque management, throttle doesn't feel much different whether the entire map is at 100% or 10%, yes I tried both. Is there anything else I'm missing? Anyone care to share what they consider a good derivable map for an 06 SS/SC so I can compare and make sure its just not me
 

Ross

Goblin Guru
I just got HP tuners for my 06 SS SC. I'm still running the stock tune, so I need to be gentle on throttle in 1st gear, but the Goblin is driveable. Have you already downloaded some 06 SS SC tunes from HP Tuners library?
 

DCMoney

Goblin Guru
I've compared it to the stock maps on HPTs Library, didn't see any difference. It must just be me being too picky. When I rode in Lonnys stock SS/SC I didn't notice any bounce in the throttle but it must be since he has thousands of miles on his or he could have started off in 2nd. Just not what I was expecting.

I did buy a used pedal and took it apart to see about swapping the springs with something stronger, theres 2 35 lb/in torsion springs in the throttle pedal, the size is something custom, nothing mcmaster or any other off the shelf spring company has.
 

ctuinstra

Goblin Guru
Ours has gotten really bad at times. I was pretty good with the throttle but there is something else going on. I can drive it up our gravel driveway and bounce a little bit and it pretty steady but take it out on the road in 2nd gear and as I'm tipping into the throttle is goes in to the bounce mode. Not every time, but it can catch you off guard. I think there is something else wrong with ours. I haven't played with it yet, too hot out to put me in the mood to work on it.

I'm thinking about dumping the LTFT table and letting it start over. Whatever it is, it has gotten worse over the last couple hundred miles.
 

Briann1177

Goblin Guru
LTFT shouldn't have anything to do with throttle response and sensitivity. Their sole purpose is for maintaining proper AFR over the long run.
 

DCMoney

Goblin Guru
Set my TM table back to stock, added a pretty stout extension spring to the pedal, its way stiffer, too stiff, but I'm glad I was able to test a stiffer throttle pedal. Can still get it to bounce but was able to drive around in first much easier than before.

Think I'm going to stop messing with it until i'm able to drive on the road and see what real driving conditions are like, not the 15mph neighborhood driving I'm currently doing.

 

Jonathan O'Hara

Active Member
I spoke too soon about re-implementing stock TM as fully fixing the problem. It really helped, but there’s still decent room for improvement for me. Maybe I’ll try going more conservative even than stock TM. I also like the idea of a stiffer pedal. I’m keeping watching this thread for good ideas ...
 

DCMoney

Goblin Guru
I spoke too soon about re-implementing stock TM as fully fixing the problem. It really helped, but there’s still decent room for improvement for me. Maybe I’ll try going more conservative even than stock TM. I also like the idea of a stiffer pedal. I’m keeping watching this thread for good ideas ...
I emailed Lokar since they make aftermarket pedal assemblies for throttle by wire GM's, will see what they say.

I thought about putting something like a little gas strut on it to take up the bounce.

View attachment 9579
Ordered those off amazon to test.
 

ctuinstra

Goblin Guru
That looks like a great set up with the gas strut, but will it allow the pedal to return to the full up position quickly?
Yeah that could be scary. The angle of mounting will also effect the curve of the action (more at the beginning of the strike versus less at the end, etc.).
 

DCMoney

Goblin Guru
Haven't attached it well enough to be able to test it yet but with my hand holding it in place. If it doesn't extended back to closed throttle fast enough I wont be using it.
 
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