Went to test the car at a local track yesterday, continuing to shake down the swap, the new brakes etc.
My car had developed a clunk in the rear that didn't seem to manifest itself in any other way. You can hear a mild version of it in this video, at 4:07 (listen for a dull thunkthunkthunk).
I tried debugging it, but couldn't find anything obvious. I raised up the rear and tried turning the wheels. At one point in the wheel rotation I could feel a metal on metal rubbing, very slight, like a fresh brake job with the pad rubbing in one spot. I thought maybe the brakes are dragging or maybe the handbrake (the pads are new, perhaps I screwed something up). But then I saw that when it's in the area where it rubs, it takes a few MM going back or forward before the dragging is perceptible. In other words, it was like I could flip it back and forth through gear lash, before rotating whatever it was that's dragging. It felt very minor when in the air like that, I figured it's a dying half shaft, so I'll wait until it blows.
So Saturday after around 5 laps, coming out of a tight right-hander and getting on the power, a noise appeared from the rear like a wheel was loose - I know the sound because I've driven a car that I forgot to tighten the lugs on fully. It happened too fast with too much adrenaline but from what I remember, I think with each clunk the car would jerk slightly.
After inspecting everything and making sure there is nothing terminal, I limped it back to the pits. The rear end was tight, no wheel play. I jacked up the rear and tried turning the wheels. At one point in the wheel rotation, that rubbing has turned into binding - so much so that it's hard to turn the wheels through it slowly (like roll up to the point, stop, and try to push through).
So whatever was clunking is now fucked up. I'm going to dig into it this weekend but I was hoping you guys could add anything to my plan that I'm overlooking.
So far it's as follows:
1) Jack up the rear end with wheels free
2) Disconnect one halfshaft from the diff, rotate that wheel
3) If no binding, repeat on the other side
4) If no binding, pull the diff
I don't think it's anything forward of the diff pinion, because then the binding/noise would happen 3.25 times per wheel rotation, not once... I'm thinking a fried CV joint, bearing or broken tooth on the diff ring.
For the record, the RX7 fronts with hawk HT10s all around provide awesome braking power! I'm probably exaggerating in the eyes of those who have driven real race cars but I've never experienced anything like this. First off the HT10s are fine for the street, they just bite normally. But after a lap or so, once they got some heat in them, holy Jebus! With the RX7 calipers and the 25mm MC, I breathe on the brake pedal and I'm hanging off the belts. I had to move my braking points back at first because I had to get used to how much torque the first few pounds of force on the brake pedal provide, to learn to modulate it. So all in all this is the ideal mod. I qualify that as something that never makes you think about it - in this case, I don't have to think about how hard to push the pedal this time or if it's going to work as well as it did last time.
My car had developed a clunk in the rear that didn't seem to manifest itself in any other way. You can hear a mild version of it in this video, at 4:07 (listen for a dull thunkthunkthunk).
I tried debugging it, but couldn't find anything obvious. I raised up the rear and tried turning the wheels. At one point in the wheel rotation I could feel a metal on metal rubbing, very slight, like a fresh brake job with the pad rubbing in one spot. I thought maybe the brakes are dragging or maybe the handbrake (the pads are new, perhaps I screwed something up). But then I saw that when it's in the area where it rubs, it takes a few MM going back or forward before the dragging is perceptible. In other words, it was like I could flip it back and forth through gear lash, before rotating whatever it was that's dragging. It felt very minor when in the air like that, I figured it's a dying half shaft, so I'll wait until it blows.
So Saturday after around 5 laps, coming out of a tight right-hander and getting on the power, a noise appeared from the rear like a wheel was loose - I know the sound because I've driven a car that I forgot to tighten the lugs on fully. It happened too fast with too much adrenaline but from what I remember, I think with each clunk the car would jerk slightly.
After inspecting everything and making sure there is nothing terminal, I limped it back to the pits. The rear end was tight, no wheel play. I jacked up the rear and tried turning the wheels. At one point in the wheel rotation, that rubbing has turned into binding - so much so that it's hard to turn the wheels through it slowly (like roll up to the point, stop, and try to push through).
So whatever was clunking is now fucked up. I'm going to dig into it this weekend but I was hoping you guys could add anything to my plan that I'm overlooking.
So far it's as follows:
1) Jack up the rear end with wheels free
2) Disconnect one halfshaft from the diff, rotate that wheel
3) If no binding, repeat on the other side
4) If no binding, pull the diff
I don't think it's anything forward of the diff pinion, because then the binding/noise would happen 3.25 times per wheel rotation, not once... I'm thinking a fried CV joint, bearing or broken tooth on the diff ring.
For the record, the RX7 fronts with hawk HT10s all around provide awesome braking power! I'm probably exaggerating in the eyes of those who have driven real race cars but I've never experienced anything like this. First off the HT10s are fine for the street, they just bite normally. But after a lap or so, once they got some heat in them, holy Jebus! With the RX7 calipers and the 25mm MC, I breathe on the brake pedal and I'm hanging off the belts. I had to move my braking points back at first because I had to get used to how much torque the first few pounds of force on the brake pedal provide, to learn to modulate it. So all in all this is the ideal mod. I qualify that as something that never makes you think about it - in this case, I don't have to think about how hard to push the pedal this time or if it's going to work as well as it did last time.
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