Clunk when going into first gear?

[huma]

Almost every time I shift into first gear, there's a loud clunk noise. Anyone else have this issue or know why it's doing this?


I have about 250 miles on my BRZ and the grinding/syncro crunch is now gone from second gear. I guess the triple cone syncro's had to be broken in?
I'm about 80 city/20 hwy and I'm getting 28 mpg on my first tank of gas. This is pretty amazing.


Can't wait to fully break in the vehicle and push my brz a little harder.

[Bonburner]

This is normal according to most people.
This is the same tranny from the lexus IS line .. which is loud.
I personally like it.

you might wanna try search/technical sub forums

[Grimlock]

It's normal. I think it's even mentioned in the owner's manual.

[huma]

Originally Posted by Bonburner

This is normal according to most people.
This is the same tranny from the lexus IS line .. which is loud.
I personally like it.

you might wanna try search/technical sub forums

Same transmission as the IS250? I'm a little disappointed, I thought they would've built a better or modified one for our cars

The auto transmission otoh is amazing. I would've purchased an auto if I didn't love driving manual so much.

[Bonburner]

Originally Posted by huma

Same transmission as the IS250? I'm a little disappointed, I thought they would've built a better or modified one for our cars

The auto transmission otoh is amazing. I would've purchased an auto if I didn't love driving manual so much.

I've only heard good things about them, I'll have to dig around to find that post and how much hp/torq they can handle.
I remember it being higher than anything I plan on in the next few years though.

[Chauntalei]

Originally Posted by huma

Same transmission as the IS250? I'm a little disappointed, I thought they would've built a better or modified one for our cars

The auto transmission otoh is amazing. I would've purchased an auto if I didn't love driving manual so much.

It's based on the Aisin unit from the IS250, but it's been heavily modified. I don't have my source on hand, but I remember reading somewhere that approximately 80% of the parts have been changed out. Someone feel free to correct me if i'm wrong though.

[Sigh-on-Rice]

If you want to avoid that noise, you could press on the clutch in neutral for 3-5 secs before putting into 1st gear.

[Shinji2787]

Originally Posted by Chauntalei

It's based on the Aisin unit from the IS250, but it's been heavily modified. I don't have my source on hand, but I remember reading somewhere that approximately 80% of the parts have been changed out. Someone feel free to correct me if i'm wrong though.

This is more or less accurate. Its based on the same unit but not the same tranny.

Also I think I remember reading somewhere that this tranny unit cannot handle all that much extra torque and hp above stock safely... Someone feel free to correct me if I'm wrong though.

[Kuros]

I know this is an old thread... forgive me.

But does anyone know the exact cause of the clunk?

[SirBrass]

Originally Posted by Shinji2787

This is more or less accurate. Its based on the same unit but not the same tranny.

Also I think I remember reading somewhere that this tranny unit cannot handle all that much extra torque and hp above stock safely... Someone feel free to correct me if I'm wrong though.

Stock trans (not sure about clutch) is rated for just above 200 ftlb torque (about 210). In practice it's been found that it can handle above 300 just fine if you're nice to it. The number at which your trans gears go ka-boom is supposed to be 400. Don't get close to 400.

You'll obviously need a different clutch for those much bigger numbers, but the trans will hold them reasonably well enough. Otherwise, start looking into stronger gears that will hold higher tq without an issue.

[chas3wba0]

Originally Posted by Kuros

I know this is an old thread... forgive me.

But does anyone know the exact cause of the clunk?

Yes, the intermediate shaft is still spinning after you clutch in and come to a stop, so when you put it into 1st, it brings the shaft to an abrupt stop. Sometimes, you can feel the car get bumped forward a little bit. It's normal and can be avoided:

Originally Posted by Sigh-on-Rice

If you want to avoid that noise, you could press on the clutch in neutral for 3-5 secs before putting into 1st gear.

[Kuros]

Originally Posted by chas3wba0

Yes, the intermediate shaft is still spinning after you clutch in and come to a stop, so when you put it into 1st, it brings the shaft to an abrupt stop. Sometimes, you can feel the car get bumped forward a little bit. It's normal and can be avoided by clutching out in neutral first.

Thank you!

Appreciate that.

[wheelhaus]

Chas3wba0 is correct. You're hearing the effect of the 1st gear synchro doing its job. The transmission is stopped, so selecting first forces the input and intermediate shaft to suddenly stop as well.

It is also repeatable after you've stopped. If you reengage the clutch in neutral before selecting first each time, the engine (via clutch) will spin the input shaft. If you hold the clutch in for 5-6 sec the input shaft and intermediate shaft will have enough time to slow down on their own, so when you select 1st it's silent because nothing is spinning.

[chas3wba0]

Originally Posted by Kuros

Thank you!

Appreciate that.

No problem, I was confused when I first noticed it too and read a similar explanation somewhere else on this forum. Did a bit of research and confirmed that it is most likely true

Also corrected my post because my last statement was slightly inaccurate