Background: My tranny in my 1988 Rx-7 N/A has been grinding really bad since I bought it. Today we replaced it with a tranny out of a 1987 N/A.

Info: I was going to replace the clutch but NAPA f*cked up and game me a clutch for a turbo model. When we got the tranny off and looked at the clutch it was still in pristien condition. Still as thick as the wrong one they gave me and everything else still looked good so we used it again.

Problem: Now that we have the new tranny in there is a pretty bad vibration/sound. Inside the car you can hear it comming from where the shifter is/ under the consol. Its the worst right around 2500RPM (I haven't taken it above 3500RPM). You can feel it in the steering wheel, seat and it vibrates the consol. We did not mark the driveshaft because it wasnt marked when we changed the diff pumpkin and it still ran smooth. Now we are maybe thinking its off balanced (but would that cause such a drastic vibration)?

Also, we just disattached the slave cylinder from the top of the tranny, didnt disconnect any hoses or anything... 2 bolts. I put it back on the exact same way. My clutch now feels mushy all the way through, I have no change in resistance when I push it in/let it out.

The vibration is the main issue here, If any one has any feedback or might know what the problem is please let me know.

EDIT: Are the output shaft splines different on a 86/86 tranny then on a 88 tranny? Maybe they are, we did use the same driveshaft that was on my car before....

 

Well i have the same exact problem basically but it with the engine mount on the oil pan. Mine is because of the off balance and not in the right place, so you might wanna get that checked out, check all mounts, and see if they are all in good condition and what not....

 

One possibility for the vibration is that the pilot bearing was damaged when you installed the transmission.

A possibile reason for the clutch could be that the transmission front cover piece where the throwout bearing slides wasn't cleaned and greased well enough.

 

I'd suspect the driveshaft. I had the same problem after a tranny swap. Loosen all the driveshaft bolts and see if you can tweak it a little. Make sure all the bolts are the same length, same number of washers, same thickness nuts. Doesn't seem like it takes much to throw them out of balance.

 

I second the Pilot bearing guess. I messed up the pilot bearing putting a clutch in and i had a simler problem. Are you having this vibration with it in gear or just free reving??

 

pilot would only cause an issue with the clutch pedal depressed, moving or stationary it would be the same feeling. if there is no vibration with the pedal out then rule out the pilot bearing.

if this is a vibration noise that only comes in with the vehicle moving then it could be a driveshaft issue but driveshafts are only speed relative so if this vibration does not change only with vehicle speed then rule out the driveshaft. if the vibration is speed relative then it can be either the driveshaft or transmission output shaft bearing.

if this is with the clutch depressed with the vehicle stationary or moving then you either have a throwout bearing that is failing/failed or the pilot bearing has gone south. clutch pedal out in neutral while stationary is a input shaft bearing in the tranny.

 

Well the vibration is RPM relative. The car revs up fine and there is no vibration when in neutral IIRC. The tranny came in a parts car, I was told that the tranny was still good and they never had an issue with it.

EDIT: I need to get to work in the morning, would it be ok to drive my car?

 

I double checked today and it still makes that vibration and noise when I rev it and its in neutral or the clutch is in. Maybe i dont have the pressure plate on correctly?

 

check all your mounts. were the alignment dowls in the engine when you installed the trans? try fliping the driveshaft 180 deg. still not sure if your vibration is whhile driving, rpm related only or speed related. does it vibrate in every gear at the same rpm, or the faster you go the worse it gets? these are key questions to figuing out your vibration. also is with the clutch depressed or released or both?

 

Sounds like you should just take the tranny back out and inspect everything before you ruin something.if the throwout bearing wasn't correctly installed; that could directly affect clutch pedal feel.and the throwout bearing touches the pressure plate at all times even when the car isn't in gear, so if the throwout bearing isn't connected to the fork inside the tranny correctly (i.e. sitting sideways on the fork) that could explain the vibration and the shitty pedal feel.

 

The vibration is RPM relevant. Every gear/ neutral/ with the clutch in, it vibrates in accordance to the RPM. It starts to get bad at about 2500RPM. I stay under that for the little bit of driving I must do for these couple of days.

The throw out bearing sitting improperly might be the issue, I was also thinking maybe the pressure plate is on wrong. We ligned it up with the dowels before putting the bolts in and it seemed to fit properly but there might be a different orientation possibly?


If it happends when the clutch is in (being reved) and when its in neutral (being reved) then it cant be the tranny itself so its in between the tranny and the engin...clutch componet?

 

When i install my pilot bearing wrong. My trans made some bad grinding noise even if the clutch is not pressed in. Last christmas eve my input shaft on my trans seized to my E shaft because of a failed pilot bearing. The bearing was turned to dust when i remove the trans. Again i had the grinding noise just free reving the engine. I am not sure why but when i replace the bearing the noise went away. Good luck!

 

It was just mentioned in my thread on Beyond.ca that the spongeyness might come from the clutch disk being in backwards, would that also cause the vibration?

http://forums.beyond.ca/showthread.p...hreadid=147498

 

yes an improperly installed disk would cause a vibration. if the disk is backwards then you most likley scored your flywheel. most clutch disks are very difficult to install backwards. not sure about the sevens haven't done one yet.