Back on Track

[Victorofhavoc]

Sounds like another adverse consequence of having the clutch and brakes share fluid. Nothing to be done about it, but is that your read?

Obviously track use is hard on the brakes and the fluid, but in my experience not very hard on the clutch - I think street driving is worse. Of the track cars I've had I've never changed clutch fluid until I had to have the motor out (for various issues) and changed the clutch preventively.

(I've changed clutch fluid on plenty of cars, but that was because they were old and there were symptoms. I'm not against it, I just don't think track driving should make it worse.)

Correct me if I'm thinking about this wrong.

As far as sharing a res, I think it's a personal view point if it's truly problematic or not. It kind of depends on your use case and frequency, but I can see it having benefits for the dealer and driver at service time. It pretty much guarantees the fluid will be changed, since people often forget about clutch fluid. For cases like this, yeah it's annoying but not the end of the world.

To be fair, I'm MUCH more annoyed Honda and acura didn't find a way to rotate the turbo 90 degrees so the intake has a shorter and direct inlet path, the cold side of the turbo stays separate from the exhaust, and the exhaust would have a straight down run instead of a right angle. Maybe ac packaging just got in the way, but it seems like a miss if they didn't even consider it.

I will say when I started bleeding the clutch, before my pressure bleeder forced air in, I DID get air out of the line. Once it was bleeding manually I did find contamination in the clutch as well. Whether this contamination is enough for most people to notice will vary.

I've had clutches work perfectly fine, and then after 40 mins on track fall straight to the floor without engaging the friction disc or pressure plate at all. It all depends on your heat and the system. If you delete the slave cylinder and clutch delay valve, it's much more likely to see clutch heat issues, and you'll definitely need to rotate at least yearly. With them, the cdv will prevent the friction disc from quickly slamming and generating more heat, while the slave cyl will add extra pressure which masks any smaller bubbles. It's also dependent on how much heat your engine is transferring to the transmission. Some cars just run hot (like my Z that runs oil at 285F even with a 32 row oil cooler). Other cars are just bad at transferring that heat elsewhere or don't have a ton of trans fluid so it overheats quickly.

Once I got most of the old fluid out via the driver's caliper inside bleeder, the clutch really didn't have much of the old fluid left. It didn't take a tremendous amount of bleed before it started running much clearer. Maybe two tablespoons or so.

Given how quick and easy it is to bleed manually after doing brakes, I would honestly just throw it onto the todo pile. It's already there, and worst case you can pay a kid (your own or a neighbor's if you don't have your own) to pump the clutch for you a dozen times. 5$ for 15min is a deal for any kid, lol.

Sponsored

 

[Victorofhavoc]

Looks like I'll need to add changing/bleeding fluid to my to-do list for this car, which is EVER-GROWING.

So now @Victorofhavoc, explain to me like I'm 4 years old the difference between camber-correcting ball joints and a roll-center adjuster? Whiteline makes each for these cars.

Also looking at finally just ponying up for an MBRP exhaust and PRL HVI.

Camber adding ball joint will increase "static" camber, but the roll center (not to be confused with "center of gravity") will not be affected. Typically if you lower a car, your center of gravity goes lower, but your roll center stays the same, which means it moves up in relation to the car.

Roll center adjustment changes one or more "pickup" point on the suspension, usually raising an inside joint or lowering an outside one to bring the motion of the control arm back in the same range as factory.

This is all especially important on a McPherson strut car because the shock travel is so limited and the suspension by nature of design gains positive camber after the lower arm outer joint crosses the lateral line of where the inner joint sits. If you can picture the lca, lowering it on the outside or raising it on the inside will angle it downwards more, so that lowering the car means the arm sits at the same angle as it did factory.

This making sense in my head as I describe it, but it's not the easiest thing to visualize. Let me know if I'm not being clear enough and I can find a different way to paint the picture.

 

[RamVA]

As far as sharing a res, I think it's a personal view point if it's truly problematic or not. It kind of depends on your use case and frequency, but I can see it having benefits for the dealer and driver at service time. It pretty much guarantees the fluid will be changed, since people often forget about clutch fluid. For cases like this, yeah it's annoying but not the end of the world.

To be fair, I'm MUCH more annoyed Honda and acura didn't find a way to rotate the turbo 90 degrees so the intake has a shorter and direct inlet path, the cold side of the turbo stays separate from the exhaust, and the exhaust would have a straight down run instead of a right angle. Maybe ac packaging just got in the way, but it seems like a miss if they didn't even consider it.

I will say when I started bleeding the clutch, before my pressure bleeder forced air in, I DID get air out of the line. Once it was bleeding manually I did find contamination in the clutch as well. Whether this contamination is enough for most people to notice will vary.

I've had clutches work perfectly fine, and then after 40 mins on track fall straight to the floor without engaging the friction disc or pressure plate at all. It all depends on your heat and the system. If you delete the slave cylinder and clutch delay valve, it's much more likely to see clutch heat issues, and you'll definitely need to rotate at least yearly. With them, the cdv will prevent the friction disc from quickly slamming and generating more heat, while the slave cyl will add extra pressure which masks any smaller bubbles. It's also dependent on how much heat your engine is transferring to the transmission. Some cars just run hot (like my Z that runs oil at 285F even with a 32 row oil cooler). Other cars are just bad at transferring that heat elsewhere or don't have a ton of trans fluid so it overheats quickly.

Once I got most of the old fluid out via the driver's caliper inside bleeder, the clutch really didn't have much of the old fluid left. It didn't take a tremendous amount of bleed before it started running much clearer. Maybe two tablespoons or so.

Given how quick and easy it is to bleed manually after doing brakes, I would honestly just throw it onto the todo pile. It's already there, and worst case you can pay a kid (your own or a neighbor's if you don't have your own) to pump the clutch for you a dozen times. 5$ for 15min is a deal for any kid, lol.

Thanks.

I should correct myself. I was talking about our casual track day cars, which have never had clutch issues (only motor issues). But we have had an issue with a couple endurance race cars (E30 and E36) where we literally had to lift the clutch from the floor by foot every time we shifted. But I think in both cases the slave cylinders were bad.

With that said, it's annoying that the systems are linked. Clutch fluid should be trouble free for at least a decade.

 

[Victorofhavoc]

I did quite a few laps in the car today with both the traction partially off and full off. I didn't feel it intervening a ton at partial off, but it definitely didn't let me snap the rear out whenever I wanted. It seemed to be using the rear brakes to slow the inside wheel in slip circumstances, which led to a touch of understeer but nothing horrendous. I measure temps after the fact and one rear rotor was nearly double the temp of the other, and it was the mostly inside one. Full off, the other side was marginally hotter at the end of a 30min session.

The car drove pretty great overall! It was quicker than expected and I ran very consistent 1.48s once everything was warm. The tires are pretty consistent and didn't grease very quickly, so the special "DT1" ps4s is definitely different from a typical ps4s. I was told by tirerack the DT1 on differ in tread pattern, but the DT1 tread looks identical to my other 3 sets of non DT1 ps4s. However, this ps4s behaved very differently on track, with the consistency of a 200tw, but the ultimate grip of a 300tw. For reference, with a very similarly setup gti, my friend ran 1.56s today and my personal best in my old gti on a set of yoko a052 was a 1.45. I have full confidence with a better 200tw tire I could get it to a 1.45 to 1.46! That's pretty awesome for an otherwise stock car! Also, in my racecar, on a Hoosier slick, I ran a best 1.31 on a different day. Comparable days, my estimate would have been around 1.35 to 1.36....so yeah 10-12s off of a full racecar pace in the same power to weight category is a very solid performance from the type s!!

I can't stress enough how much better the carbotech xp10 brakes are than factory. Their compression is non existent and you basically have a rock hard pedal at all times. With ti shims, fluid never boiled and wear on the brakes looked great. These brakes are a bit much for a 300tw, but the ps4s is no ordinary 300tw so it performed admirably. The consistency of the brake was my favorite part of driving the car today. It could use a bit more top end power, honestly, but I would NOT add any torque. It has more than enough torque as is, and even a drifter that drove it today mentioned the surplus of torque compared to his drift stang. The xp10 pads were also a breeze to drive to and from the track (2.5 hrs away). They're noisy... They grind, they squeak, they squeal, and they make the racecar noises, but highway they're dead silent and quite solid. Their only issue on the highway is how aggressive the acc becomes, and how easy it becomes to touch the brake gently and suddenly slow 10mph,.

I liked the mounting location of the camera, and eventually I placed my lap timer up high and to the right with a ram mount x. That all worked beautifully, but the gopro failed to start a few times. It'll take me a couple days to pull a proper video out and post something up. Unfortunately audio sucked because the exhaust is super silent. Tire squeal was present all the time, and I'm totally okay with that because it means the tires are communicating. I'd like to move the mic into the hatch next time, but today my cable wasn't long enough.

I did have one recurring issue. Every hot session out, the car would throw a light saying "brake system" and in my best cheeky Jeremy Clarkson impression I could certainly say, "Yes! It does exist!" It would clear on a restart and didn't effect performance or function in any way. My guess is that with all the trail braking, abs activating, and regular slip angle happening that the electronics are just being stupid and throwing some silly code. No one else driving my car had it happen, but to be fair the next fastest person was 10s slower.

Everyone that drove the car, including me, commented on how oversteer prone it was! The back end was constantly wanting to press out and even through the many sweepers at this track it was keeping the front level and planted while allowing the rear to slip around. Go in too hot and you certainly get understeer, but keeping the brake pressure in check and smoothly letting off, led to a lot of quite fun rotation.

The suspension i eventually set to sport in individual mode and that's what led to the fastest times. I didn't notice any excessive body roll. The roll that was present was quite beneficial to the weight transfer and ultimately the grip the car was producing. The roll, at least to me, I sport mode seems very well matched to a 200 or 300tw tire. This is also not an easy or ultra smooth track, so that does play a roll (dad pun ).

Ps4s are a bit soft and sometimes funky on tire pressure. After a few sessions of tuning with temp, feel, and chalk I found the sweet spot to be at around 40psi front and 35 rear when hot in pit temp/pressure. With a smoother track, I bet 42 to 44 front might be needed.

If I missed anything or anyone has other questions, please do ask. Again, I'll have video up sometime this week.

 

[Victorofhavoc]

Thanks.

I should correct myself. I was talking about our casual track day cars, which have never had clutch issues (only motor issues). But we have had an issue with a couple endurance race cars (E30 and E36) where we literally had to lift the clutch from the floor by foot every time we shifted. But I think in both cases the slave cylinders were bad.

With that said, it's annoying that the systems are linked. Clutch fluid should be trouble free for at least a decade.

If you put in an rb600 type like I did, you'll get two years max before the fluid itself is shot. Whether that affects you as much as it would on the brake system is kind of hard to tell on a street or dual duty car. Sensitive fluids are just sensitive fluids though, so not isolating the brake and clutch here is definitely annoying.

I would kill to drive an E30 endurance car! I've driven one sorted e36 and it was a whole bucket of fun.

Sponsored