Clutch, Slave, or Transmission?

[Matt]

Ive watched a lot of the ETCG videos on youtube and theyre great – Ive tried doing my homework on this one, but Im having trouble diagnosing the real issue.

I have a 2004 Cadillac CTS-V with a Tremec T56 manual transmission. The car has 86k miles and lately it seems to be getting difficult to shift. It started out with difficulty shifting into reverse, but after changing the fluid it improved. Now it seems getting the car into 1st at times doesnt feel smooth – still goes in easily, but it just feels different. Now its getting quite hard to shift into 2nd. I usually have to wait for rpm’s to drop before it shifts into gear. The rest of the shifts feel good, but it just feels odd. Cant really detect a significant slip in any gear, but I did cause a massive slip one time when I hit the gas hard in 1st gear when the clutch was cold. I could smell burnt clutch, but it didnt seem to change performance. Another point worth noting is that on flat ground without any brake, putting the car in first with the clutch depressed makes the car move forward an inch or two.

At first I thought clutch, but since the car doesnt normally slip, i started to question that. Also, I thought a bad clutch would make all shifts hard. I then started to think that maybe the slave was bad because when I bought it, the reservoir was empty. I check it often now and it has stayed full. The pedal feels smooth and firm, but the clutch releases very late and almost at the released position. Lately im starting to wonder if one or more of the synchros or forks are going out since its just the 1-2 shift that gives me so much trouble.

I plan to put in a new clutch soon (already ordered) along with a new slave, but as long as I have the trans out I wondered if I should be tearing it apart….any thoughts or explanations for my symptoms?

Thanks!

Topic

[JoshMc]

First of all let me say that I am not a transmission expert by any stretch of the word but I have worked on cars my entire life and have done countless clutch jobs for myself and friends, family and customers over the years. That said, I personally think that your issues are probably all coming from the clutch being bad. When you get the transmission down I bet that you are going to find the fingers on the pressure plate bent or warped. When these fingers get bent the slave cylinder can’t fully release the clutch friction and this makes it hard to get into gear when the vehicle is not moving. It also can cause reduced clamping force on the clutch disk which causes slipping like you mentioned. If it were in my shop I would wait until I got the transmission down and inspect the clutch assembly before deciding to take it to a transmission specialist to be rebuilt. You will also want to get the flywheel resurfaced or replaced when you change the clutch to ensure that the new one performs the way it should. Good luck and I hope this helps.

[dreamer2355]

I would also see if you have any way of trying to adjust the clutch on that vehicle along with pedal free play but again i agree with Josh.

Keep us posted.

[Matt]

Thanks for the replies and confirmation of what I was thinking. I ordered an upgraded LS7 clutch out of a Z06 for my car that will come complete with flywheel, friction disc, pressure plate, slave, and pilot bearing. I’m also putting in a speed bleeder so I can bleed the clutch in the future to keep the fluid clean and dry. On that note, it’s a hydraulic clutch so there is no adjustment to my knowledge.

[EricTheCarGuy]

You’re correct that there is no adjustment on that clutch. By the sound of it the clutch isn’t releasing. This could be due to a hydraulic leak in the clutch system OR there could a problem with the clutch itself. Since you’re changing the clutch you’ll be able to inspect it for signs of wear, if you don’t see any then look to the trans. It’s more likely to be a clutch problem by your description. Lastly it’s important you use the correct fluid in the transmission so be sure you’re using the manufacturer recommended fluid.

[Author]

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