I have a 2005 6 speed manual with 30,000 miles. I bought it with around 15,000 miles. The car has never shifted as smooth as I had hoped. The last couple months at times it is very difficult to downshift from fouth to third or third to second. Any help would be appreciated

 

I'm sure your doing this but, are you pushing the clutch in all the way when you shift? Hope you figure it out. Check your clutch fluid also. You might be low. Good luck.

 

I have no trouble downshifting. However when the temp outside is below 50 it grinds a bit till it gets to operating temp. Has since the day i drove home with 0 miles on her. Its definately not the smoothest gearbox, thats for sure. Hope you figure it out.

 

First thing I would do is to service the clutch fluid. These cars have been known to not fully release the clutch as the fluid becomes contaminated.

Review this thread:

http://forums.corvetteforum.com/c6-z...-and-cure.html

Hope this helps.

 

I will definitely have the clutch fluid replaced. Should I use any specific type of fluid? How much (quantity) do I need to buy?

 

V8.. if you are going from 4 to 3.. what RPM or mph are you in 4th going down? does it grind? or just hard to push it into gear?

with the fluid swap i bought 4 bottles of the dot4 fluid.. and then went from BLACK as night fluid to clear in 5 cylces of flushing procedure and didnt even use 1/2 a bottle. I would look at the clutch fluid flushing procedure and give it a try.. 1 bottle should be more then enough IMO.

 

No grinding going from 4th to 3rd, just very hard to push into gear. Going from 3rd to 2nd requires even more "grunt from my arm." Strange that it only sometimes happens. Most shifts are easy. This happens with conservative driving. I would estimate shift between 2000-2500 rpm.

 

I did this on my 05 and it sure seemed to help. I also think my MGW shifter has been a big help, but from your description, your issue seems "clutch-centric".

 

An occasional hard shift could be caused by an intermittent clutch problem. I'd try the path of least resistance first. I'd repeatedly flush and fill the clutch fluid per the 'Ranger' method until the fluid is clean. GM makes a clutch/brake fluid. I've used Prestone DOT 4 with good results and I now use Motul 600 fluid with good results.

I'd replace the transmission fluid. I use Royal Purple Syncromax but obviously this isn't the GM recommended tranny fluid.

With the engine off try shifting through the gears (up and down) paying attention to the 'feel' of the shifts. Does it feel reasonably smooth or do you note a specific binding at certain points? Is there excessive movement in the shifter? Start the engine and try shifting up and down through the gears again paying attention to the 'feel' of the shifts. Note any excessive shifter play and if there's any binding.

If after replacing both the clutch and transmission fluids if the problem still persists I'd have it checked-out at the dealership. It could be a problem within the transmission (syncros, etc.) or perhaps with the clutch.

Good luck!

 

I'm experiencing what sounds like exactly the same thing with my 32K mile 2006 C6.

Is the clutch fluid supposed to be clear? Mine is very dark (and a bit low at the bottom of the reservoir) This weekend I'm gonna pull out the center console (again) to check that the aftermarket shifter is in good shape (it came off once!). Never has a problem upshifting and the downshifting problem happens at normal, conservative driving speeds. One thing I just noticed: it happened more often than not today, but in the last couple of blocks I tried doing FAST 3-2 downshifts, and it didn't happen any of those times?

 

As stated above, by tranny is also grumpy when it's cold, does this happen when it's warmed up?... On a separate note, is it still difficult to get it into the next lower gear if you double clutch and match revs in neutral? This should not be required, but it would be interesting to see how it responds. If you clutch, shift to neutral, let out the clutch, blip the gas to the appropriate rpm for the next lower gear, clutch again and drop it in, it should go in like hot butter. The clutch has to be closed during the blip...

 

Mach VI, the slower you downshift, the more the engine spools down, and the more work the syncro's have to do to match the speeds of the two sides of the tranny. It is no surpise that a slow downshift results in more resistance than a fast one. With the double clutch procedure posted above, you're matching the speeds of the two sides of the tranny yourself, so the syncho's don't have to do much... if your blip and timming is accurate.

 

I have 2005 Vert and had great difficulty down shifting into first. Overall the car shifted poorly. Solution:
1. get clutch fluid clear
2. replace transmission fluid with synthetic. I used Amsoil ATF synethic which I believe meets warranty requirements.
3. anti -venom method. This involves putting 3/16 copper washer on side of transmission to reduce tension. My dealer was kind enough to do this for me.

The car now shifts fairly smoothly. My next change will be to add a heavy shift **** as the stock one is very light.

 

Thanks for the replies... first time I posted a question on the forum and man, did you guys respond quickly!

I understand about the fast vs slow shifting, but the thing that's got me concerned is that this is a definite change of behavior. I'm not shifting SLOW, I'm shifting normal and it's refusing to let me downshift quite frequently. This is also not a COLD tranny, it's an afternoon commute in California.

While I haven't tried the double clutch method you suggest, I do believe, based on similar experiments that this would probably allow it to shift better.

I'm going to look up the fluid change I saw mentioned and make sure my aftermarket shifter isn't coming loose (again!).

 

change it!!

 

Thanks, folks. I'm baffled how changing that little bit of reservoir fluid could make a difference, but as that seemed easier than tearing my console apart to check the shifter, I started with the fluid. Since it was an intermittent problem (but becoming more frequent) it's hard to say if it fixed it, but after about 5 miles and 40+ shifts, I could not induce the downshift lockout problem, so if I don't post again this weekend, then that fluid swap did the trick... and it was so easy! I wonder what a dealer would have put me through? Fingers crossed!

 

you could always swap in a torque tube, diff and a6 into your car....

 

what is the anti venom method, never heard of it?

 

Some good advice in this thread.

To which I'll just add....

Everything the car does depends on a properly functioning clutch. Keeping that requires a small investment of time to do routine maintenance of the clutch fluid. If you make that investment, the clutch hydraulics will give many miles and years of high-performance driving.

The big mistake by many owners is avoiding clutch fluid maintenance until issues arise. Much better to prevent the issues from ever occurring.

Clutch fluid maintenance protocol

Ranger

 

I thought the simple fluid change had (surprisingly) fixed things up, but I'm sorry to report it didn't... or didn't much. After profiling this problem for a couple of months I have some new observations. The downshift lockout only occurs when I press the clutch, but then don't actually shift for several seconds. I often do this in commute traffic when I pre-emptively prepare to do a downshift because of traffic slowing up ahead, or because I begin a shift and then coast because the traffic flow suddenly changes, so I hesitate to do the downshift. I don't feel like I'm doing anything really odd, and it took a long time to realize there was a connection. I'm sure I've been doing this preparatory clutching my entire life and I've never experienced a downshift lockout on any other car. It's also a definite change of behavior as the exact same driving style never produced this behavior in the first 3 years of owning the Corvette. The other clue remains that it never happens during upshifting, only downshifting with the clutch pressed a couple of seconds early. It never happens when I clutch & shift quickly. Revs are not high, and I am not pushing the engine/tranny at all. When it happens, I have to blip the throttle do make the gear engage. Does this sound like it could be a worn synchro issue? Flywheel? Ideas? Or should I just break the old habit and stop clutching early?