What could cause this?
08-07-2010, 05:19 PM
#1
What could cause this? So I've been having problems with 4th gear grinding lately. My buddy and I just pulled the transmission and clutch from the car to see if there were any visible signs of damage to anything. We found out that my supposed Luk Pro Gold clutch was in fact just a OEM replacement from them. So I now have a monster stage 3 that I'm going to install.
Before we put the transmission back into the car we decided to pull the mid plate and input shaft and take a quick peek at the 3/4 shift fork and synchro assembly. There was no visible damage to any of the parts (even the stock pads) so we cleaned out the casing, made sure there was no bearing damage, and resealed the mid plate back onto the the transmission. We were just about ready to put it back into the car when we decided to spin the input shaft. When going through the gears from 1st to 3rd, the input shaft spins fairly easily. As soon as you try to spin it in 4th gear it becomes VERY hard. If you shift it to 5th and spin it then go back to 4th it becomes SIGNIFICANTLY easier to turn. But also when you pop it into neutral and spin the shaft, then go to 4th gear, it spins with ease. This seems to be a intermittent problem as it does not do it every time. Does anyone have any idea what could cause this?
Initially we were thinking that the grinding was caused due to a bad synchro, but it looks fine as stated above. The car already has a steel 3-4 shift fork and it is not bent. Not sure what could be going on here. Any help with the problems is greatly appreciated.
Before we put the transmission back into the car we decided to pull the mid plate and input shaft and take a quick peek at the 3/4 shift fork and synchro assembly. There was no visible damage to any of the parts (even the stock pads) so we cleaned out the casing, made sure there was no bearing damage, and resealed the mid plate back onto the the transmission. We were just about ready to put it back into the car when we decided to spin the input shaft. When going through the gears from 1st to 3rd, the input shaft spins fairly easily. As soon as you try to spin it in 4th gear it becomes VERY hard. If you shift it to 5th and spin it then go back to 4th it becomes SIGNIFICANTLY easier to turn. But also when you pop it into neutral and spin the shaft, then go to 4th gear, it spins with ease. This seems to be a intermittent problem as it does not do it every time. Does anyone have any idea what could cause this?
Initially we were thinking that the grinding was caused due to a bad synchro, but it looks fine as stated above. The car already has a steel 3-4 shift fork and it is not bent. Not sure what could be going on here. Any help with the problems is greatly appreciated.
08-07-2010, 05:50 PM
#3
They appeared to be lined up correctly. Maybe we should take it a part and check again? Anything else to look for? If the synchro was in fact bad wouldn't there be some wear showing also? What else would cause it to grind JUST in 4th gear if the synchro was good? Thanks for the help Mike!
08-09-2010, 07:51 AM
#5
They appeared to be lined up correctly. Maybe we should take it a part and check again? Anything else to look for? If the synchro was in fact bad wouldn't there be some wear showing also? What else would cause it to grind JUST in 4th gear if the synchro was good? Thanks for the help Mike!
It's hard to verify the fork pads since you can't take off the synchro ring/fork from the front. They'll have to be inspected as carefully as possible as they can get compressed down and appear ok, but still cause problems..
As an aside, 4th gear can cause issues if the pilot bushing is bad, and may have been your initial grinding.... It should be checked and maybe just replaced anyway..
08-11-2010, 11:55 PM
#6
Well got the new stuff installed (Monster Stage 3, new slave, pilot bearing, already had a tick master). Still grinding going into 4th. Looks like I will be sending the transmission off to have it gone through. The clutch feels good though!
