Tranny Whine
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Joined: Jun 2005
Posts: 50
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From: Manhattan Beach CA
Tranny Whine
Hey guys,
I have been a fan of the forum for a while and finally managed to join. I have a polo green 96 lt4 coupe sitting in the garage. I picked it up back in January and the very first day I drove it I had a bit of a heavy foot and long story short I ended up spinning a rod bearing and had an expensive rebuild on my hands. I didn't have the time to do the work myself so when I finally got it back from the shop I expected it to be perfect. Well aside from a slight rocker issue at first, the motor runs great... however, now whenever I drive it my transmission whines at me. Before it was quiet during shifts regardless of clutch being depressed or not, now if I have the clutch in and not moving it is quiet, also if it is in neutral regardless of speed, but when I start moving it sounds like a turbo spooling up almost. The frequency of the whine increases with rpm and is the same regardless of which gear I am in. Of course I brought up this issue with the shop that did the work and they told me it is a common issue with the zf-6 tranny and its throwout bearing. The only fix would be to replace the throwout bearing. Having the motor just put back in and only having gotten to drive the car once in the last 4 months a whining noise as long as it wasn't damaging anything was acceptable to me. What do you guys think about the noise, and also any other possibilities it could be? I was thinking there was a slight possibility the synchros could be going out on me... that would suck... as if an lt4 crankshaft was hard enough to source. Sorry for it being so long!
Thanks,
Dan
I have been a fan of the forum for a while and finally managed to join. I have a polo green 96 lt4 coupe sitting in the garage. I picked it up back in January and the very first day I drove it I had a bit of a heavy foot and long story short I ended up spinning a rod bearing and had an expensive rebuild on my hands. I didn't have the time to do the work myself so when I finally got it back from the shop I expected it to be perfect. Well aside from a slight rocker issue at first, the motor runs great... however, now whenever I drive it my transmission whines at me. Before it was quiet during shifts regardless of clutch being depressed or not, now if I have the clutch in and not moving it is quiet, also if it is in neutral regardless of speed, but when I start moving it sounds like a turbo spooling up almost. The frequency of the whine increases with rpm and is the same regardless of which gear I am in. Of course I brought up this issue with the shop that did the work and they told me it is a common issue with the zf-6 tranny and its throwout bearing. The only fix would be to replace the throwout bearing. Having the motor just put back in and only having gotten to drive the car once in the last 4 months a whining noise as long as it wasn't damaging anything was acceptable to me. What do you guys think about the noise, and also any other possibilities it could be? I was thinking there was a slight possibility the synchros could be going out on me... that would suck... as if an lt4 crankshaft was hard enough to source. Sorry for it being so long!
Thanks,
Dan
Melting Slicks
Joined: Apr 2003
Posts: 2,150
Likes: 6
From: NS
Originally Posted by Maverik
Of course I brought up this issue with the shop that did the work and they told me it is a common issue with the zf-6 tranny and its throwout bearing.
Throwout bearing = No.
Transmission alignment = YES!
If it didn't do it before pulling the engine, and now it does it, then they haven't got the transmission lined up perfectly. When it's not aligned it whines like a bugger, and it doesn't have to be off my much - we're talking thousands of an inch. There is a GM Tech Bulletin on this. The Tech Bulletin recommends re-torquing the bell housing, then transmission, and finally the support beam. Make sure the support beam is aligned properly, there's a procedure in the Service Manual for this. They may have left a bit of dirt or a burr between one of the components as well. Trust me, it doesn't take much.
You can have them do a quick test. Loosen the transmission bolts off, support the transmission with a jack. Start the engine and let it idle in neutral. Now try jacking the transmission up and down just a little. You'll notice a big difference in the transmission noise in neutral. Re-torque it where it's the most quiet.
