Neodied's #375 Extended Track - 07 SS/SC donor

neodied

neodied

Well-Known Member
Specifically regarding the clutch, I assume I need a new one based on:
- engagement point seemed to be about halfway through the travel
- dumping the clutch on a couple 2-3 shifts didn't result in the jerk I was expecting
- RPMs did not change quickly, it was much more of a smooth RPM decline when on throttle after a shift

So assuming I need a new one, my first thought is aluminum flywheel plus one of these options from ZZP:
- LSJ OEM Upgrade Clutch (https://zzperformance.com/collections/transmission-drivetrain/products/lsj-clutch-upgrade-kit)
--- Least torque holding capacity according to ZZP, but also the cheapest and not super stiff according to some people here
- South Bend Stage 3 350ft-lb (zzperformance.com/collections/transmission-drivetrain/products/south-bend-stage-clutches)
--- I don't think I'll ever hit the 350ft-lb ceiling on this, but it is more expensive and there are some reviews saying they had throwout bearing issues
- Clutch Masters Stage 3 470ft-lb (zzperformance.com/collections/transmission-drivetrain/products/clutch-masters-stage-clutches)
--- Way overkill torque rating, might be too stiff, also pretty expensive
Overall I'm leaning toward the OEM LSJ Upgrade one, placing a high priority on drivability.

Replacing the clutch will probably lead to more throttle bounce issues, so saving this thread for the future:
 
Last edited:
Rauq

Rauq

Goblin Guru
neodied said:
That's a fair point. I guess if I really want to have the lights off in a particular situation I could turn them off auto or switch to parking lights on the stalk.
Click to expand...
I believe with an '07 donor you will have a DRL fuse in your fuse box. With it in and the ambient light sensor plugged in, in the daytime, you should get half voltage on the high beams. Pull the DRL fuse and you get nothing during the day unless you turn on the headlights or park lamps on the stalk.
 
Robinjo

Robinjo

Goblin Guru
One of my exhaust ports didn't blue at the same rate as the others, it ended up doing it later on though.

I have the upgraded LSJ clutch and lightweight flywheel, it's smooth. Are you sure you fully bled the TOB? It can be a pain to do without a pressure bleeder. In the end, unless you turbo swap the LSJ you won't get to it's hold capabilities.
 
neodied

neodied

Well-Known Member
On second thought, if there is air in the clutch line, wouldn't that result in different symptoms? Bear with me and my novice understanding of clutch mechanics, but with air in the lines, the pressure plate wouldn't fully release from the flywheel, right? That would result in some level of torque being applied even when the clutch is fully depressed because it didn't disengage completely.
 
Robinjo

Robinjo

Goblin Guru
neodied said:
On second thought, if there is air in the clutch line, wouldn't that result in different symptoms? Bear with me and my novice understanding of clutch mechanics, but with air in the lines, the pressure plate wouldn't fully release from the flywheel, right? That would result in some level of torque being applied even when the clutch is fully depressed because it didn't disengage completely.
Click to expand...
It's just something to confirm before spending about $400-600 on parts overnighted from Japan. How did you bleed the clutch system?

I used this below and bleed the system, be sure to order the GM vehicle attachment if you go this route. Still with the P-Bleeder on, I closed the line and had my wife work the clutch 3 times holding the last one to the floor. Then I cracked the valve to release the air from the TOB. I do this a few times (maybe 4 or 5) until I feel like it's ok. This method has worked well 4 times (and counting) now.

This thing makes bleeding the clutch and brakes a breeze.....
42730
 
G

Gtstorey

Goblin Guru
neodied said:
On second thought, if there is air in the clutch line, wouldn't that result in different symptoms? Bear with me and my novice understanding of clutch mechanics, but with air in the lines, the pressure plate wouldn't fully release from the flywheel, right? That would result in some level of torque being applied even when the clutch is fully depressed because it didn't disengage completely.
Click to expand...
Those are the symptoms you would normally expect from a poorly bled clutch.

Although I'm not sure what you mean by this "- RPMs did not change quickly, it was much more of a smooth RPM decline when on throttle after a shift". Typically a slipping clutch would gain rpm rapidly with an increase in speed with the clutch engaged
 
neodied

neodied

Well-Known Member
Gtstorey said:
Although I'm not sure what you mean by this "- RPMs did not change quickly, it was much more of a smooth RPM decline when on throttle after a shift". Typically a slipping clutch would gain rpm rapidly with an increase in speed with the clutch engaged
Click to expand...
I see how that is a bit vague. What I meant was that on a 2->3 shift when dumping the clutch and immediately re-applying throttle, the RPMs didn't sharply drop as I would expect from a clutch dump in an upshift. Although it's possible that I was lighting up the rear tires, but it didn't feel squirrelly and @SmsDetroit who was following didn't mention any tire smoke.

This problem needs data (said the engineer). Next time I have some cruising to do I'll connect a data logger and try to get wheel speed and engine speed vs time plots. As long as the clutch is engaged, engine / wheel speed should be a constant for each gear.
 
G

Gtstorey

Goblin Guru
It's been a long time since I drove a vehicle with a slipping clutch. I think it was most pronounced when going from a low load to a high load quickly. High gear, low speed to WOT and throw in a hill?
 
Robinjo

Robinjo

Goblin Guru
Gtstorey said:
It's been a long time since I drove a vehicle with a slipping clutch. I think it was most pronounced when going from a low load to a high load quickly. High gear, low speed to WOT and throw in a hill?
Click to expand...
The last one I had, when you shifted gears the clutch would drag for a bit before grabbing. The RPM's would shoot up then come back down as the clutch/flywheel worked. And, if you got on the throttle hard in gear the rpms would rise, from the clutch not grabbing the flywheel.

His symptoms could be a clutch. I just like to try the cheaper and easier methods first (when I can).
 
neodied

neodied

Well-Known Member
Proper alignment makes a huge difference. I finished the DIY alignment to approximately these specs for both front and rear:
Ride height: Lower control arms level
Camber: -0.5
Toe: 1/8" in
Caster: ¯\_(ツ)_/¯

Took it out for a quick spin and I'm very impressed. It tracks straight now without the nervousness over rough road and elevation changes. Threw it around some corners and it feels like it's on rails. The harder I turn in, the better it corners. Man it feels good. It does need more power though. Now that it feels solid, I want to be able to break the rear loose with throttle. Next season goal: ~260hp
 
Desert Sasqwatch

Desert Sasqwatch

Goblin Guru
DF recommended castor is 8+/-1 degrees negative (that's leaning toward the back). Maybe you got lucky and have the castor within limits, if you followed the recommended set up for the UCA/LCA. Good work!
 
neodied

neodied

Well-Known Member
Desert Sasqwatch said:
DF recommended castor is 8+/-1 degrees negative (that's leaning toward the back). Maybe you got lucky and have the castor within limits, if you followed the recommended set up for the UCA/LCA. Good work!
Click to expand...
I did follow the DF guidelines, but I don't have turn plates to measure that angle correctly. Doesn't seem like a huge priority to tackle at the moment since the driving dynamics feel good enough. Eventually I'll probably take it to a racing shop nearby that does alignments for custom builds. My boss built a rock crawler and got his done there with good things to say.
 
neodied

neodied

Well-Known Member
Going out for another run tonight, I noticed that my dipstick had popped out from a previous drive. My valve cover port is plumbed into the intake barb as intended (didn't block it off), so I'm guessing the PCV valve needs to be cleaned.
 
Rttoys

Rttoys

Goblin Guru
neodied said:
I did follow the DF guidelines, but I don't have turn plates to measure that angle correctly. Doesn't seem like a huge priority to tackle at the moment since the driving dynamics feel good enough. Eventually I'll probably take it to a racing shop nearby that does alignments for custom builds. My boss built a rock crawler and got his done there with good things to say.
Click to expand...
You don’t exactly need the turn plates. The front end is light, so the tires don’t grab on a slick garage floor. If they do put a piece of cardboard under the tires so they slide better. To get your 20* turn each direction, you can use painters tape on the floor to make your measurements. You’ll find it’s close to one revolution of the wheel. Then just use an angle gauge.
46DFC47F-E53E-4F09-B23F-CE053E68F24A.jpeg
 
neodied

neodied

Well-Known Member
I think I do need to add more caster to my alignment. Driving it a couple more times, it didn't self-center as much as I'd like. The never-ending alignment continues...

I got an AEM wideband AFR sensor+gauge kit and HPTuners link cable so that I can log the AFR analog output alongside HPTuners data for tuning.

Things I'd like to explore with HPTuners:
- Idle undershoot in neutral coming down from high RPM
- Stall protection for future grabbier clutch (sub-idle RPM torque target?)
- Turn on intercooler pump always/sooner?
- AFR especially under load
 
neodied

neodied

Well-Known Member
I tempo-perma-rarily wired in the AFR sensor, gauge, and HP Tuners data logger. Just to satisfy my curiosity, I took a short log of crank and idle. And to my untrained eye, the behavior of the spark timing and Short Term Fuel Trim looks.... interesting...
42994

I could definitely hear the oscillations as well. It looks like STFT hits a cap at ~12%.
I didn't have the AFR analog input mapped correctly in this data, but watching the gauge showed oscillations from 14.2 to 15.5 or so during this period, which makes sense to me if the STFT is positive, adding fuel to try to compensate for the lean AFR.

Seems like it's fair to assume that this is sub-optimal behavior and I should try to tune it to not use so much STFT and stick roughly at 14.7 without oscillation at idle. I'll be watching some Goat Rope Garage to learn what knobs to start fiddling with.
 

Attachments

G

Gtstorey

Goblin Guru
I don’t know the particulars of tuning the lsj but if the other parts of the tune need tweaking, the ECM will adjust spark to hold the idle. Spark is the quickest reaction to adjust that it has for idle speed adjustment.
 
Last edited:
Rauq

Rauq

Goblin Guru
STFTs don't look suspect to me. That's how it dials towards stoich with a sensor that can only read like 14.6-14.8, is to shoot high and then low and target oscillating around stoich with each swing. If it shoots high and then low and never reads rich, then it knows it's lean. Eventually, though, those oscillations should center right at or around stoich. LTFT should be the way it re-centers the oscillations. Looks like you don't have any LTFT at the moment, which could either be because they're turned off in the tune, or it hadn't idled long enough to start getting into LTFT.

If you log B1S1 O2 voltage, it should swing up and down as well.
 
You must log in or register to reply here.
Top