Sup guys? New here. Just picked up a 03 supercharged 6spd G35 sunday and Ive already put almost 700 miles on it. (mainly from the drive home).

Anyway, the car only has 35,000 original miles so Im not sure if this is an issue or safety feature but the car shifts fine, but when it comes to down shifting it just will not do it. I can go all the way to 6th and if I want to down shift in to any gear I have to drop to second (it will let me) then quick go for whatever gear Im looking for.

Ive done a lot of searching on google already but didn't have any luck, they are all talking about the auto's in manual mode.

Is there a RPM limit or do I have an issue? Thanks!

 

Get it retuned

 

That's it?

 

A tune isnt going to help your 6MT shift any better. So you're saying when you are in 6th, and you try to downshift into say, 3rd, 4th, 5th it will not go into gear? Does it grind or just not let you push it into gear? How is the upshifting? Does it seem like the upshifts are a little too stiff, or notice any small grinds going up into 2nd, 3rd, 4th? Does it grind at all when you are stopped at a stop light and try to put it into 1st gear?

Next time you drive it get it all the way into 6th gear on the highway. Then, pump the clutch pedal 8-10 times and try down shifting into 4th gear.

Shifting at a precise RPM wont have much effect on shifting (in normal driving applications) due to the way the synchros are designed. Once the clutch is disengaged there isnt much correlation between engine RPM and how the transmission shifts aside from whatever leftover speed the input shaft carries after the clutch is disengaged while you're shifting. This also implies that your clutch is operating properly.

 

Are you rev matching when you downshift, or just trying to throw it into a lower gear with the clutch disengaged?

 

I think he's insinuating that it wont go into gear at all. Rev-matching will help, but it will go into gear just find without doing so. If rev-matching is the only way to get it to go into gear it would point towards the clutch system being at fault and not fully disengaging. Sort of like shifting without using the clutch. Even with the clutch fully engaged you can rev-match and if you time it right, it will fall right into gear.

 

This is too strange, there's no reason if you can up shift you shouldn't be able to downshift. Time to visit a trans shop and ask them these questions. We can speculate on the cause all day long and you still won't have an answer!
Gary

 

once the clutch is depressed all the way he should be able to shift to any gear besides 1st. if he cant even get into gear wat good is rev matching? unless im missing something here

 

Nothing essentially. its more for preserving your clutch and to avoid shocking the engine too much during down-shifts.

But I'm kinda with Gary. We can speculate but thats just about it. Typically if you can upshift fine, then you should be able to downshift relatively well also. Its a weird symptom to have.

 

Taking it in to get looked at... Definitely not normal by any means. Probably comes along with the territory of buying a heavily modified car though....

 

If you double clutch and rev match while in neutral but before putting it into the next gear, this can help isolate problems with synchros since the transmission input shaft will already be spinning close to the speed of the other side of the transmission. You have to do it with a double clutch though, since if you rev match while simply holding the clutch down, your transmission input shaft will not gain speed in line with your engine revs.

This is actually the way I drive in all downshift situations and even in some upshift situations. It saves wear on your synchros. If optimizing pure speed and acceleration is the goal, then you wouldn't do this in straight line driving since it takes longer to double-clutch(more so in upshifts).

 

This situation, as strange as it seems could happen to a car that is factory fresh and has never been modified. I can't speak for all owners but every mod I've made has been an upgrade with the best parts available regardless of cost....Gary

 

im guessing previous owner probably beat the **** out of the trans thus extreme case of syncro problem vs the common mild syncro problem

 

Next time you drive it get it all the way into 6th gear on the highway.

 

Sorry just got back from Vaca in Myrtle Beach, hadn't been online.

Anyway, car shifts great up, does not grind in any gear and never has, shifts right in, not stiff at all. Ive had a lot of 5spd cars and never seen anything like this before.

I see there is a little confusion over what I said originally, let me try to explain better.

Start out in first or second, shifts all the way to 6th great. No issues. Reserve also, no issues. If so to say Im in 4th, I can not down shift to 3rd unless I hit 2nd first. I don't even have to put it all the way in 2nd, I just have to move to second bump down a tad almost like I was about to shift in 2nd then I can quick hit 3rd. Or if Im in 5th, I cant down shift in to any other gear besides 2nd and quick jump to the gear I want. 6th, same way, I cant down shift to 5th, 4th or 3rd. I have to bump 2nd and switch quick to the gear Im looking for.

Ive tried rev-matching, Ive tried double clutching, Ive even pumped the clutch several times in neutral and it still will not downshift.

It does have a stage 2 clutch installed 2k miles ago. The car is basically brand new. The guy I bought it from bought it at 30k miles, sunk all sorts of money in to it and only put 5k miles on it in the 8 years he had it so he decided to sell it. I uploaded a few pix of it.

I did notice when shifting sometimes I can hear the clutch pop up, like the pedal itself sticks, maybe from lack of the car being driven, idk. Havent had time to fool with it much yet, but sometimes when I let off the clutch it will get stuck in the "freeplay" area and pop up. Prob going to bleed the system just to see if that helps and throw some grease on the pedal arm.