I posted this in the general discussion a week ago but didn't get much replies so figured this is a better category. I have a 2006 z51 with 29k

Driving my car today , on several occasions the transmission grinded going into first gear. This happened in a couple different situations. Earlier in the day it happened twice from a stop going into first gear( with the clutch pressed in). Most importantly this happened every time with my clutch fully in though. It would still go in but would just make a loud grind.

Sometime first gear will work completely smoothly and other times it will happen every other start. Let me stress that every other gear works like butter, and when the first does work it is also flawless.

I did also notice now that if you shift into first EXTREMELY slow then most the time it will go in without any noise, but it only happens when done at regular shifting speed. When the grind happens the speedometer goes crazy and jumps up to either 20mph or 200 and then back and the 'instant mpg' goes to 20 for a split second!

What could this possibly be??? I know first thing that pops into head is syncro, and thats what dealership said they think it might be, but it kinda just doesn't make sense for a first gear syncro to go as the gear doesn't get much shifting stress. Also aren't first and 2nd gear syncros same syncro(or is that older cars).

I do have a callaway shifter that i installed by myself about a year ago, is there something I can do like some kind of alignment that could cause a grind in first gear?

Monday I think I am going to bring it into a local corvette shop for an inspection for 70 dollars, but if there are things I can try on my own,like shifter alignment, then I would rather do that. Then on Tuesday I have appointment at dealership to rip it apart and fix it,in case the final decision is that its syncro(they said since first gear syncro is such a rare thing to go GM might reimburse part of the process).

I tried searching for how to do some kind of shifter alignment in C6 but came up empty.

Anyone have any advice?!

EDIT: small breakthrough... Just tried to take the car for a spin testing different things. IF I shift into second and go straight to first then there is no problem. Does this mean anything??

So kinda like when someone tries to shift into first at a light and sometimes cant but has to shift to second then first, thats what fixes my issue.

 

The callawy shifter should not be the source of your problem. Let's start with the simple stuff. How is your clutch fluid and when is the last time you changed it? If not recent try the Ranger method.

I have no idea why a tranny problem would cause your speedo to go crazy.

 

I have a similar problem going from 1st to second under WOT.

I believe its my syncro going out, regardless im having the tranny pulled soon and upgraded.

 

Well about a year ago I changed about 10 reservoirs full of clutch fluid via the rangers method, and since then I change the reservoir every month or so. The fluid is no longer on the clear side anymore though, so I can try to change a couple reservoirs again.

Yea thats the funny part, I have no idea why the tranny would make speedo go crazy.

 

I dont know about the the speedo, but after i installed a clutch, I also must have installed my shifter in a bound up postion, I took it apart and the llinkage from tranny seemed to have some play in it, so i set the shifter midway in the play, im talking where the linkage meets the shifter, then mounted the shifter to the tube. it really is a poor design but after that little adjustment the whinning stopped

 

On my 06 a snap ring broke in my manual tranny and damaged the first gear synchro. Repaired under warranty. Good luck.

 

Thanks for the replies guys. Going to mexico for the weekend then monday morning taking it into corvette shop for them to do a an assesment. If its anything expensive like the syncro Ive already decided what im gonig to do. Im thinking about gettnig supercharger kit, so Ill get that and I will have to probably replace the clutch anyways within two years so Ill fix it then. Going from second to first really doesnt bother me 2000 dollars worth

 

I had that happen to me a year ago. Same stuff with the speedo jump and grinding and stuff. It ended up being that the tranny mainshaft bearings were busted and were grinding around in my tranny...that ended up damaging my synchros as well. I ended buying a new mainshaft because it was gone where the bearing was supposed to sit, and replaced all synchros. Parts were about $800 and labor was $1000. I also ended up replacing the the clutch and clutch master and slave cylinders which was more. It was a big fix and it sucked......got to pay to play. I drive the **** out of my car though. I really beat on this thing...probably why I didn't buy an old 360 or a TT Porsche....I could not afford to drive those cars the way I drive this thing. Good luck and I hope this is not your situation.

 

1. Did you do this at dealer that that is how much it cost?
2. Was this just in first gear you had problems, or is it in every gear, which is what it sounds like.

 

Do you powershift by any chance?