alex44 Posted April 29, 2022 Share Posted April 29, 2022 Really at my wits end here and would really appreciate some help. As title suggests I had the 5 speed transmission rebuilt from my '78 280z and it's still making noise... Some background info - a while ago I was on the highway and tried downshifting from 5th to 4th but it refused to go in and I heard the terrible ass puckering grinding noise of the synchro dying. Eventually after a few attempts I got into 4th gear. When I exited off the highway and came to a stop I noticed a rattle type noise which I thought at first to be rod knock. Quickly figured out that pressing the clutch pedal in made the noise go away so I assumed a bearing inside the trans was toast. Took it to a transmission shop that was recommended by a few local Z guys who I trust and really know Z cars well. The shop had a overhaul kit (new bearings and synchros) already in stock and I told the tech who was doing the work to replace anything inside that he thought needed replacing. After 6 weeks they said the car is ready to be picked up. I get there the tech comes back from a test drive and first thing I notice is the rattle is still present. Tech claims he inspected everything thoroughly and thinks it's one of the gears having superficial damage causing the rattle and there's not much we can do about it, basically says to insulate the car better and live with it. After spending $2000 and this is the end result I'm very very unhappy to say the least. I replaced all clutch components less than 4000km ago. A friend and I removed the slave then pushed the TOB off the pressure plate then started the car, rattle still there. Can hear the rattle in 1st, 2nd, and in neutral, while stopped or moving, but goes away when clutch pedal pushed in. I can't think of anything else it might be other than a bearing on the input or countershaft.. but they have allegedly all been replaced.. I'm at a loss on what to do here. Car drives and shifts great, it did even before the rebuild, but that rattle is horrible and makes for a miserable driving experience. Will try to upload a video of the rattle. It's late now and I'm tired so if I forgot to include anything that may help point to a solution just ask. Thanks. Quote Link to comment Share on other sites More sharing options...
alex44 Posted April 29, 2022 Author Share Posted April 29, 2022 https://m.youtube.com/shorts/7i40qUvmeYU Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 29, 2022 Share Posted April 29, 2022 Get a list of all of the bearings that they replaced. The adapter plate bearings are tough to do, they might have skipped those. Any notes on how far down they took it would help too. Since you told them to only replace what they thought was worn they might not have gone very far. More details on what happened after you forced it in to 4th might help. Did you drive it afterward? How did it get to the shop? Did the problem go away? Quote Link to comment Share on other sites More sharing options...
alex44 Posted April 29, 2022 Author Share Posted April 29, 2022 (edited) 1 hour ago, NewZed said: Get a list of all of the bearings that they replaced. The adapter plate bearings are tough to do, they might have skipped those. Any notes on how far down they took it would help too. Since you told them to only replace what they thought was worn they might not have gone very far. More details on what happened after you forced it in to 4th might help. Did you drive it afterward? How did it get to the shop? Did the problem go away? Sorry yes my post was long and a bit confusing with how I worded it.. late night posting.. anyways, what was discussed with the shop was that they were to pull the trans apart and rebuild with the overhaul kit (https://www.transmissionpartsdistributors.com/fs5w71a-fs5w71c-transmission-rebuild-kit-with-synchro-rings-fits-77-84-datsun-nissan-200sx-280z-280zx-maxima-pickup-bk104ws/). On top of installing that overhaul kit I told the tech if he sees ANYTHING else inside the trans while it's apart that isn't included in the kit and needs replacing to do so, which he didn't as there was nothing in the bill that said he did so. After I ground the gears about 3 times trying to get into 4th I put it into neutral, slowed down, and shifted into 3rd. I then sped up and went to 5th and tried to downshift into 4th again which it did successfully. I figured it was ok at that point and I must have been sloppy with my 5th to 4th downshift and continued home which was about 10 mins away. On the way home at a red light I noticed the rattle which never went away. Carefully drove it for about a week as it's my daily and then brought it to the shop for the rebuild. Edited April 29, 2022 by alex44 Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 30, 2022 Share Posted April 30, 2022 You can find quite a bit around the various Datsun forums about the noise from the transmission when in neutral with the clutch engaged. Might be that your 4th gear grind just made you hyper-aware. I had three different 5 speeds in my car at various times and they all had the noise that went awya when you pressed the clutch pedal. I have a memory of @JMortensen telling a story about a new rebuild having the noise. I found one. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 30, 2022 Share Posted April 30, 2022 Yep. Can add that the noise is a lot more prevalent in cars with light flywheels. Here's a thread from Miata.net where they talk about the rattle associated with light flywheels, with one person describing it as I usually do, sounding like marbles rolling around inside the transmission. I think the consensus is that it's gear lash, and the gears in the trans are rocking back and forth between power strokes, so the lighter the flywheel and the slower the idle speed and the lopier the cam, the more likely you are to hear it. https://forum.miata.net/vb/showthread.php?t=732227&highlight=flywheel+rattle Quote Link to comment Share on other sites More sharing options...
alex44 Posted April 30, 2022 Author Share Posted April 30, 2022 3 hours ago, JMortensen said: Yep. Can add that the noise is a lot more prevalent in cars with light flywheels. Here's a thread from Miata.net where they talk about the rattle associated with light flywheels, with one person describing it as I usually do, sounding like marbles rolling around inside the transmission. I think the consensus is that it's gear lash, and the gears in the trans are rocking back and forth between power strokes, so the lighter the flywheel and the slower the idle speed and the lopier the cam, the more likely you are to hear it. https://forum.miata.net/vb/showthread.php?t=732227&highlight=flywheel+rattle I think this is my issue here.. some play between one of the gears is what the rebuilder told me he thinks it is. I don't have a lightweight flywheel but plan to lighten up the stock one soon. Guess there's really not much I can do except live with the noise since the trans shifts totally fine? The shop who rebuilt it even said they would rip it apart again under warranty which I'm considering having them do.. probably gonna end up sourcing another used 5 speed and put that in. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 1, 2022 Share Posted May 1, 2022 Yeah, I'd learn to live with it, especially if you're going to lighten up the flywheel (which is very worthwhile). Quote Link to comment Share on other sites More sharing options...
alex44 Posted May 1, 2022 Author Share Posted May 1, 2022 Ugh... That really sucks having spent 2 grand to still have this rattle and there's nothing we can do to fix it.. if it's in fact coming from the gears. Maybe some thicker oil, cabin insulation, lightweight flywheel, and louder exhaust will allow me to put up with it.. if I simply can't live with the noise after all of that Ill just have to locate a used 5 speed. Lots of 4 speeds here but since Im often on the highway that likely would be a bad decision. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted May 1, 2022 Share Posted May 1, 2022 Also consider a 240sx 5 speed, have your existing 5 speed belhousing machined to work. I think there is also a TL70 adapter coming to the market soon. That my be a good new/newer 6 speed replacement option for you Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 2, 2022 Share Posted May 2, 2022 4 hours ago, alex44 said: Ill just have to locate a used 5 speed. I think that what we're saying here is that they all do it. Another used one will to. And the 240SX 5 speed (AKA 71C) is essentially the same design as the 71B. Not sure but it probably does it too. Quote Link to comment Share on other sites More sharing options...
alex44 Posted May 2, 2022 Author Share Posted May 2, 2022 (edited) 5 hours ago, Dat73z said: Also consider a 240sx 5 speed, have your existing 5 speed belhousing machined to work. I think there is also a TL70 adapter coming to the market soon. That my be a good new/newer 6 speed replacement option for you Yes definitely, I'm keeping an eye out for a 240sx trans since they aren't very challenging to fit to a z from what I've gathered. I'll look into the tl70 adapter.. I know there is a 350z trans adapter on the market but that's going to be out of my price range. 44 minutes ago, NewZed said: I think that what we're saying here is that they all do it. Another used one will to. And the 240SX 5 speed (AKA 71C) is essentially the same design as the 71B. Not sure but it probably does it too. I have to disagree with this to some extent. Sure every single Z transmission that I've driven, including my own, had some minor 'whirring type' noise at idle that went away with the clutch pedal pressed.. however this issue that only started two months ago (I've owned my Z for 5 years now) is a horrible sounding rattle that one might even confuse for a rod knock. If you haven't watched the video I posted I encourage you to do so as it shows the noise I'm talking about quite well. A few days ago I met up with a friend who owns a 240z. Supercharged l28, 5 speed (rebuilt by the same shop who did mine recently), fuel injection, an endless list of mods... By far the nicest Z I have ever seen, difficult to find words to describe it honestly. Its an incredible experience to drive and looks the part. Anyways his transmission had no rattle to it, only the typical whirring at neutral which was nearly drowned out by the header exhaust system. If my Z was half as nice as his I would be a very happy man.. Edited May 2, 2022 by alex44 Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 2, 2022 Share Posted May 2, 2022 39 minutes ago, alex44 said: only started two months ago (I've owned my Z for 5 years now) is a horrible sounding rattle that one might even confuse for a rod knock. I didn't watch the video. Sound rarely comes through well on the old internet from the phone recordings. If it's that bad I'd take up the shop's offer to open it up again. That's not normal. The whirring noise is. Seems like you're sampling other people's transmission noises so the picture is more clear to you now. Maybe go to the shop with somebody who has a good one so the shop knows what a good one sounds like. Good luck. Quote Link to comment Share on other sites More sharing options...
eddieeats Posted July 4, 2022 Share Posted July 4, 2022 I had replaced the gear shift bushings with brass ones, they are plastic or nylon from factory. I found that the brass ones were just loose enough to cause a rattle. I changed them back to plastic or nylon and the rattle was gone. I don't know if this is the same problem your having and I hope it is as it's an easy fix. I hope it works out for you. Quote Link to comment Share on other sites More sharing options...
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