Came back to the states for a few weeks and made it to the track the first week. Picked up the z and went over to Haydn's to reset the clutch release point. After some strange results which we blamed on the over-sized master cylinder, the pedal release point went from being barely reachable on the floor, to requiring barely any throw at the top.
I confirmed the slave cylinder was releasing all the way from under the car, so there wasn't risk of the throw being set too high, but it was definitely different driving home. If it were set too high, the clutch might not release completely while in gear, which would never be good for anyone, or the throwout bearing may drag on the clutch causing other issues. The super high release point also wasn't very good trying to stage at the track, but I'll get to that later.
Haydn's car the night before, relaxing on stands, floors still taped from last Halloween. Greenville was getting a lot of rain so it was iffy until the day of, but turned out sunny.
I have videos of both run's, or should I say 1.5 ... <que ominous music>
The first run Haydn fully staged and I ran out of time, red lighting, not being able to inch the car forward easily with the previously discussed crazy clutch release point. I was very easy on the "launch," as to ease into the whole thing. There was some wheelhop and I could feel the rear breaking loose at the top end of the gears under boost. I was running high boost, 17#s.
The second run I staged first and Haydn followed. I was a little harder on the launch, but not by much, you can hear the turbo spool a bit at idle but the rev's drop considerably as I release the clutch. Even so there was still some loss of traction off the line. There was even more wheelhop and lack of traction when boost kicked, and at the top of second the rear end completely let go and I pulled out of everything.
I thought the halfshaft broke, or maybe the companion flange. As it turns out, the differential broke in half, bits of the rear cover still bolted to the mustache bar studs, the rest of the housing and the gear carrier hanging from the front mount and driveshaft.
Based on how the RLCA's potato-chipped, or taco'd based on food preference, it looks like the LSD broke first, dropping onto the inner arm rails, bending them, the driver's side considerably more affected. The driver's side halfshaft pulled out of it's outer joint, and presumably then out of the differential.
At the end of the track, I reached under the car to see the halfshaft hanging from the ebrake cable, and I simply pulled it out from under the car as it was no longer physically attached to anything. Surprisingly the halfshaft looked to be in once piece, if not possibly bent in the middle. The companion flange was over the stub axle, the outer joint of the cv still bolted to it. This assembly looked a little off-axis as compared to the one on the other side and its own hub center.
Because of the massive force against the RCLA's, the rear drop mounts rotated forward. So much force in fact, the bushing almost pulled out of the lower drop mount, completely bending the lower U mount.
The inner and outer rails of the RCLA that run inline with the differential front to rear both bent in the middle. The outer rail is actually more of a gusset, but the 3/4" sway bar held tight, possibly assisting in this bend.
If the halfshaft had let loose first, it would have spun around, hitting the front rail of the RCLA, potentially bending it downward. Assuming the bushing stayed in the front mount, this would have pulled the forward, outer joint at the wheel inward, cause serious toe-in. This could then have caused the LSD to rip apart if the cover was as weak as it apparently is, but the RCLA's would have bent in the opposite orientation. With the taco being on the inner rail, and the rear suspension points of the drop mounts shifting forward accordingly, the culprit points back to the finned-LSD cover.
Ideas are welcome.
It was 5o$ to get the z towed back home. I was asked several times why I wasn't more distraught. Aside from my car having enough kick to literally rip it's diff out, I see this as troubleshooting. If the 24o can't pull a run down the track without exploding, then it's not done. I was surprised we found the weak link this quickly, but here we are. The clutch held, the gears held (otherwise the differential casing would not have broken), and the tires held enough to cause the above reaction.
Assuming root cause of wheel hop and 100% torque load on and off at high boost, how do you fix this? I don't want to put everything back together to have this happen again. I've asked around and this seems to be a rare event. Friends more into suspension geometry than I have suggested creating anti-squat by moving the suspension pickup points as compared the front. I think this sounds a bit much at this stage of the game and point towards the 4o year old chassis instead first. Also, this isn't a drag car, but I don't feel like it's too much to ask for her to not rip apart at 4oo wtq.
Currently there are no body mod's, no over-frame rails, no rear connectors, no upper strut bars, no cage. It's my opinion that the aft half of the car was just flopping down the track under load.
Again, ideas???
The funny part about this whole thing was the slip on the second run. Haydn pulled a 9.6 at 73 mph flooring it the whole way, beating me to the 6o' mark. The z was flying though, coasting from half track to a 9.9 at 56 mph without a driveline. Until next time.
Go team.
I confirmed the slave cylinder was releasing all the way from under the car, so there wasn't risk of the throw being set too high, but it was definitely different driving home. If it were set too high, the clutch might not release completely while in gear, which would never be good for anyone, or the throwout bearing may drag on the clutch causing other issues. The super high release point also wasn't very good trying to stage at the track, but I'll get to that later.
Haydn's car the night before, relaxing on stands, floors still taped from last Halloween. Greenville was getting a lot of rain so it was iffy until the day of, but turned out sunny.
I have videos of both run's, or should I say 1.5 ... <que ominous music>
The first run Haydn fully staged and I ran out of time, red lighting, not being able to inch the car forward easily with the previously discussed crazy clutch release point. I was very easy on the "launch," as to ease into the whole thing. There was some wheelhop and I could feel the rear breaking loose at the top end of the gears under boost. I was running high boost, 17#s.
The second run I staged first and Haydn followed. I was a little harder on the launch, but not by much, you can hear the turbo spool a bit at idle but the rev's drop considerably as I release the clutch. Even so there was still some loss of traction off the line. There was even more wheelhop and lack of traction when boost kicked, and at the top of second the rear end completely let go and I pulled out of everything.
I thought the halfshaft broke, or maybe the companion flange. As it turns out, the differential broke in half, bits of the rear cover still bolted to the mustache bar studs, the rest of the housing and the gear carrier hanging from the front mount and driveshaft.
Based on how the RLCA's potato-chipped, or taco'd based on food preference, it looks like the LSD broke first, dropping onto the inner arm rails, bending them, the driver's side considerably more affected. The driver's side halfshaft pulled out of it's outer joint, and presumably then out of the differential.
At the end of the track, I reached under the car to see the halfshaft hanging from the ebrake cable, and I simply pulled it out from under the car as it was no longer physically attached to anything. Surprisingly the halfshaft looked to be in once piece, if not possibly bent in the middle. The companion flange was over the stub axle, the outer joint of the cv still bolted to it. This assembly looked a little off-axis as compared to the one on the other side and its own hub center.
Because of the massive force against the RCLA's, the rear drop mounts rotated forward. So much force in fact, the bushing almost pulled out of the lower drop mount, completely bending the lower U mount.
The inner and outer rails of the RCLA that run inline with the differential front to rear both bent in the middle. The outer rail is actually more of a gusset, but the 3/4" sway bar held tight, possibly assisting in this bend.
If the halfshaft had let loose first, it would have spun around, hitting the front rail of the RCLA, potentially bending it downward. Assuming the bushing stayed in the front mount, this would have pulled the forward, outer joint at the wheel inward, cause serious toe-in. This could then have caused the LSD to rip apart if the cover was as weak as it apparently is, but the RCLA's would have bent in the opposite orientation. With the taco being on the inner rail, and the rear suspension points of the drop mounts shifting forward accordingly, the culprit points back to the finned-LSD cover.
Ideas are welcome.
It was 5o$ to get the z towed back home. I was asked several times why I wasn't more distraught. Aside from my car having enough kick to literally rip it's diff out, I see this as troubleshooting. If the 24o can't pull a run down the track without exploding, then it's not done. I was surprised we found the weak link this quickly, but here we are. The clutch held, the gears held (otherwise the differential casing would not have broken), and the tires held enough to cause the above reaction.
Assuming root cause of wheel hop and 100% torque load on and off at high boost, how do you fix this? I don't want to put everything back together to have this happen again. I've asked around and this seems to be a rare event. Friends more into suspension geometry than I have suggested creating anti-squat by moving the suspension pickup points as compared the front. I think this sounds a bit much at this stage of the game and point towards the 4o year old chassis instead first. Also, this isn't a drag car, but I don't feel like it's too much to ask for her to not rip apart at 4oo wtq.
Currently there are no body mod's, no over-frame rails, no rear connectors, no upper strut bars, no cage. It's my opinion that the aft half of the car was just flopping down the track under load.
Again, ideas???
The funny part about this whole thing was the slip on the second run. Haydn pulled a 9.6 at 73 mph flooring it the whole way, beating me to the 6o' mark. The z was flying though, coasting from half track to a 9.9 at 56 mph without a driveline. Until next time.
Go team.
http://forums.hybridz.org/topic/113768-r200-lsd-broke-in-half/
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