TGiuliante

Hey guys I have a C6 race car. I am having issues with third gear downshifts-it will not go into 3rd if at full tilt 6,000 + rpm then attempting to downshift into third it is like hitting a wall. It will downshjift into 4th no problem, same with second but my 4 3 downshift does not work like it should. it will not go in until I slow the car down. I tried matching the revs in all different patterns, shifting slow, shifting fast etc etc etc. I had a different driver drive call same issue. EVERYTHING in the car is NEW. this is what I have

Drivetrain is an LS2 with LS3 heads, C5 transmission NEW (this is the second transmission in car same issue, Linkage NEW, MGW shifter NEW, RPS Clutch NEW, thorw out bearing NEW came with clutch, Torque tube NEW, 390 rear NEW, Carbon driveshaft NEW.

Trans has been in and out, linkage adusted and re adjusted. We spent time on this. Has anyone experienced similar problem?

Any input would be helpful.

TOm

StreetSpeed

Hey Tom, Mark Petronis here. Sorry you're still dealing with this. I was hoping a shifter adjustment was gonna take care of it, since my car would do the same thing when not properly adjusted. Hope you get it sorted quickly.

RX-Ben

Hi Tom, this is Ben. Just want to confirm - you have a C5 trans, C5 diff AND C5 torque tube AND C5 shift linkage AND C5 bellhousing, correct? It all goes to pot/requires a bit of work if you mix and match any of those w/C6 parts (to the extent they will bolt up).
Also - did it creep at higher rpm when in gear w/the clutch in?

0Anthony @ LGMotorsports

Check the clutch....is it fully diss-engaging and also...make sure it is not over extending the pressure plate fingers or you could be damaging the clutch and also causing drag not letting it shift. Generally speaking on this every shift would have something wrong with it though...

Check the pilot bearing and front torque tube bearing...if these are not spinning freely, again it can cause drag and they don't want to shift.

Check the bellhousing...make sure it isn't cracked...make sure the mounts are not broken or moving around...if the torque tube is bending or flexing you will not be able to shift it right either.

That isn't to say the trans is 100% perfect but if it did the same thing on both trannies then I'm going to say it is something external.

fatbillybob

That sounds like clutch to me too. Lots of issues with clutches like shim or no shim. flywheels only sort of compatible with other makers pressure plates and clutch discs. clutch disc damage not seen on the outside but marcel spring broken. bad setup height that no one measures. we all assume it to be correct. add that to throwout bearing tolerances and aftermarket master cylinders and you get things that should work together but sometimes dont when out of spec. Many clutchs work fine but actually have shorter life because of these issues. Some just don't plan work. Then add in the race environment with heat expansion that a streetcar does not see or 150mph 4th gear down to 85mph 3rd gear shifts and it is amazing things work as weil as they do for as long as they do on basically street components sold as racecar level components.

1badtantrum

Check the clutch as advised above. It seems like if it were the clutch issue all shifting would be impaired. I had similar shifting issues in different gears 3-4-5. I'm tearing apart my TR6060 in my C6Z06 as a result. After much research and communication with a couple very helpful vendors, I'm going to take a look at friction surfaces of the synchros. High speed/high RPM shifts are the problem shifts. This is where the greatest friction is generated/required to match the speeds of the input/output/counter shafts during the shift. 3rd gear is one of the, if not the most used gear on the track with these corvette ratios. Here we go first one...

TGiuliante

Hey guys thanks for the input. Very much appreciated and helpful. We will be working on it! Hopefully it will not be too painful

Hi Volts Z06

Hey Tom, this is Doug- I came over to check on you with Ben last week after the drivers meeting. Did you ever try seeing if the car creeps in first with the clutch all the way in? I'm having my own clutch issues as well. We ended up pulling my driveline the week as well after the clutch refused to re-engage after a 3-4 shift during qualifying. We're thinking its a hydraulic issue and I'm wondering if you might have a similar issue.