5 Speed Tranny Noise and Vibration

Drummer

Registered User
I was on my way home from work this evening and noticed my transmission was grinding 3rd gear a bit when I was up in the rpm range. Didn't do this Friday of last week, just started today. Tried shifting to third to pass on the slow interstate and it would grind every time. When I got it around to where I live (30 minutes later). I felt a strange vibration in the shift knob when I held it as I was shifting gears. All gears shift fine but 3rd. When I pulled up in my driveway I could really tell. The shift knob was shaking as I put RPM into it and while I was rolling. Also was making a clunk, clunk noise that matched the vibration in the shifter. Please tell me this thing isn't fried. Just put it in about 6 months ago with no problems until today. 1990 Model
 
I've rebuilt a number of M5R2's and it sounds like a 3rd gear synchronizer problem. I've never had one do that though. Unfortunately, you will need to pull it and remove the top cover to inspect it and see what the exact problem is. I wouldn't drive it any more as something could break off and jam causing even more damage. I have spare internal parts if you need anything.
 
I've rebuilt a number of M5R2's and it sounds like a 3rd gear synchronizer problem. I've never had one do that though. Unfortunately, you will need to pull it and remove the top cover to inspect it and see what the exact problem is. I wouldn't drive it any more as something could break off and jam causing even more damage. I have spare internal parts if you need anything.

I don't mean to hijack this thread but since you say you have spare parts and know about these M5R2's I thought I would ask what I should be looking for, when I open up my 94 tranny? I've bought everything to swap to a 5spd but I want to go into the box to check everything out before putting it in. It has 107k on it and I was told shifted fine with no noises, grinding or vibrations. I would just feel better checking it out before the install. Are there any particular bearings that I SHOULD replace due to mileage? I've checked but all I can find in rebuild kits have brass syncro's in the kits. I'm told they replace the fiber ones?? Any help would be appreciated...
 
I've rebuilt a number of M5R2's and it sounds like a 3rd gear synchronizer problem. I've never had one do that though. Unfortunately, you will need to pull it and remove the top cover to inspect it and see what the exact problem is. I wouldn't drive it any more as something could break off and jam causing even more damage. I have spare internal parts if you need anything.

Just parked the car in the back of my property. I started it up an no noise. Shifts fine. Pondering my next move. Still wish I knew what the problem was. It shifts into 3rd fine. Only grinds a bit when I get on it. Well over 5 grand in this thing and really getting P.O.'d......
 
I don't mean to hijack this thread but since you say you have spare parts and know about these M5R2's I thought I would ask what I should be looking for, when I open up my 94 tranny? I've bought everything to swap to a 5spd but I want to go into the box to check everything out before putting it in. It has 107k on it and I was told shifted fine with no noises, grinding or vibrations. I would just feel better checking it out before the install. Are there any particular bearings that I SHOULD replace due to mileage? I've checked but all I can find in rebuild kits have brass syncro's in the kits. I'm told they replace the fiber ones?? Any help would be appreciated...

It's called a "PM"......
 
That is a bit strange. These things don't heal themselves so something is definitely amiss. I wonder if it's a clutch problem instead of a tranny problem. That could make it grind and also produce a vibration. I'd drive it some more and see if any of the symptoms come back. Keep the tow truck's phone number handy.
As for what to look for inside, check the blockers. They shouldn't be loose or dangling. They will fit flush against the synchro assembly but there should be a gap when pushed the other direction against the gear. If it fits flush with the gear and is loose it's worn out. I've never found a bad bearing in any that I've worked on. I've found damaged synchros where the teeth were worn down but those are hard to check unless you take it apart. It's normal for the input shaft to be a bit loose with side to side play but should have no front to back play.
 
This might be strange but it doesn't make the noise when the car is cold. Seems to occur when it is up to temp. Also the gear shift is kinda wobbly in all gears as far is play. I'm used to it being very stiff while driving with my hand on the gear shift knob but it really isn't. I have a spare M5R2 in my storage building that is original to the car. 2nd and 3rd where grinding in it so I replaced it with this one. I watched a few videos on you tube last night and most of those were throw out bearing noises. I could tell that because the clutch went out in my Jeep early this year. Push in the clutch and the noise goes away. Not the case here. Since the car could only be flat bedded for a tow I think I will leave her sitting. Was going to get a new paint job in Spring but not now (Viper Red). Had a guy on eBay that sold the rebuild with brass syncro's but he ran out so I suppose I will keep looking. As long as there is nothing that has to me machine pressed to put this old transmission together I suppose I will get a new kit to rebuild. What gripes me is the car runs so good in cold weather and now she sits in my yard looking a bit pitiful.
 
There are a couple of press fits. Both are the bearings on the output shaft. If you are running the brass blockers then 3rd gear will tend to crunch on speed shifts. I guess you'll just need to pull it to see what's wrong.
 
Well, I drove the car to work on Wednesday and no problems. Actually wanted it to make the same strange noise it did last week but to no avail. 3rd gear is still crunching a bit when I am shifting and a strained rate of speed climb. The noise is gone. I was kinda angry because I wanted the transmission guy to hear it so he could tell me what was wrong. Figures..... Still not sure what the problem is. Took it by Jiffy lube so they could check fluid levels and the guy said it was fine and the fluid looked fine to. Just got back from eating out at lunch and no issues. This really has me wondering. It's not like I can throw it up on a lift, pull the thing and open it up and have a "Eureka moment". Third gear never grind-ed before even when I was shifting under strain. In all my years this seemed to be a gradual and steady decline when the synchros went bad. Now 2 transmissions are crap. #1: 2nd and 3rd grinding. #2: 3rd gear grinding and the "mystery noise" has vanished. Is there a transmission that works better than the m5r2 without serious modifications? Damn........
 
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