Hunter Posted August 16, 2021 Share Posted August 16, 2021 I recently had my transmission oil changed in my 1st gen/6 speed manual. Sporadically when shifting at high rpms from 2nd gear into 3rd, I now experience a loud grinding noise. I haven't had it when downshifting. Anyone have any experience/thoughts on what this might be? Is the oil change relevant? It was done by a local specialist who, by all accounts, seems pretty "on it". And, yes, I'm depressing the clutch fully 😅 Link to comment Share on other sites More sharing options...
Aaron Posted August 16, 2021 Share Posted August 16, 2021 Try it without using the clutch. It could be that your synchros are worn. 1 Link to comment Share on other sites More sharing options...
extanker Posted August 16, 2021 Share Posted August 16, 2021 I gather it did not grind with the old oil,have you discussed this with the shop that did the work ? Why did you change the oil ? Does it grind any less hot or cold ? How does the shifter feel with the new oil ......smoother/stiffer? Link to comment Share on other sites More sharing options...
Hunter Posted August 16, 2021 Author Share Posted August 16, 2021 2 hours ago, Aaron said: Try it without using the clutch. It could be that your synchros are worn. Just jam it into gear? Is that not going to produce an even worse effect, or am I missing a joke? 2 hours ago, extanker said: I gather it did not grind with the old oil,have you discussed this with the shop that did the work ? Why did you change the oil ? Does it grind any less hot or cold ? How does the shifter feel with the new oil ......smoother/stiffer? It didn't. Oil change was overdue (due after 12 years, apparently), so was just doing it out of routine. Hot/cold doesn't seem to make a difference. Shifts are marginally smoother, but I take it transmission oil doesn't degrade very much/fast so the improvements to be had are small anyway. I'll ask the shop, but wanted to get a heads up before ponying up for diagnostics/labour time. Link to comment Share on other sites More sharing options...
extanker Posted August 16, 2021 Share Posted August 16, 2021 mileage on the car ? Link to comment Share on other sites More sharing options...
Mavrik Posted August 16, 2021 Share Posted August 16, 2021 (edited) Sounds very much like your 3rd gear syncromesh is on its way out! Not unheard of for a tranny oil change to highlight it. Syncro's would usually fail on the downshift side of gear dogs however ime. Does it crunch at ALL rpm?... Does double declutching lessen it?... What oil/spec did they use?... I always put a tube of Molyslip in when I change gear oil in tranny/diff... https://www.eurocarparts.com/p/holts-molyslip-gearbox-protection-550774644?type=shopping&gclid=CjwKCAjwmeiIBhA6EiwA-uaeFfDTSdzgP9arAh7kb2d2pbjb_nnq-_v3kdggYvkrxuSrKSXYSwOoSxoCjcsQAvD_BwE Edited August 16, 2021 by Mavrik Link to comment Share on other sites More sharing options...
Aaron Posted August 16, 2021 Share Posted August 16, 2021 5 hours ago, Hunter said: Just jam it into gear? Is that not going to produce an even worse effect, or am I missing a joke? It didn't. Oil change was overdue (due after 12 years, apparently), so was just doing it out of routine. Hot/cold doesn't seem to make a difference. Shifts are marginally smoother, but I take it transmission oil doesn't degrade very much/fast so the improvements to be had are small anyway. I'll ask the shop, but wanted to get a heads up before ponying up for diagnostics/labour time. It isn't a joke... it's an extremely valid test. If you can shift from 2nd to 3rd without using the clutch (with rev matching and some skill), then it would confirm that the synchro is worn. If that's the case: Try using thicker oil Disassemble the box and replace the synchro Replace the gearbox Link to comment Share on other sites More sharing options...
Hunter Posted August 16, 2021 Author Share Posted August 16, 2021 4 hours ago, Mavrik said: Sounds very much like your 3rd gear syncromesh is on its way out! Not unheard of for a tranny oil change to highlight it. Syncro's would usually fail on the downshift side of gear dogs however ime. Does it crunch at ALL rpm?... Does double declutching lessen it?... What oil/spec did they use?... I always put a tube of Molyslip in when I change gear oil in tranny/diff... https://www.eurocarparts.com/p/holts-molyslip-gearbox-protection-550774644?type=shopping&gclid=CjwKCAjwmeiIBhA6EiwA-uaeFfDTSdzgP9arAh7kb2d2pbjb_nnq-_v3kdggYvkrxuSrKSXYSwOoSxoCjcsQAvD_BwE Commuted home just now, tried to vary the rpms when shifting. Couldn't get it to grind at all - but certainly in the past it's only been at perhaps 4500+ (mostly closer to 6000), and only upshifting. Because it's a bit sporadic, hard to tell if double clutching helps or I've just been lucky. Annoyingly the service receipt doesn't give the oil spec, but they're a very well established specialist so I assume it's the/a correct spec. Almost certainly without Molyslip, though. 5 hours ago, extanker said: mileage on the car ? Just passed 100,000mi. Link to comment Share on other sites More sharing options...
wtaite01 Posted August 17, 2021 Share Posted August 17, 2021 16 hours ago, Aaron said: It isn't a joke... it's an extremely valid test. If you can shift from 2nd to 3rd without using the clutch (with rev matching and some skill), then it would confirm that the synchro is worn. If that's the case: Try using thicker oil Disassemble the box and replace the synchro Replace the gearbox I'm curious about this, isn't this always possible, synchro wear or not? Is there anything in particular we should expect when trying this that would indicate an issue or not? Pretty sure I do this very occasionally in other cars anyway just for (my version) of 'fun'! May be different in the Porsche for some reason, or I may be misunderstanding entirely, but keen to rectify that if it is the case Link to comment Share on other sites More sharing options...
Aaron Posted August 17, 2021 Share Posted August 17, 2021 9 hours ago, wtaite01 said: I'm curious about this, isn't this always possible, synchro wear or not? Is there anything in particular we should expect when trying this that would indicate an issue or not? Pretty sure I do this very occasionally in other cars anyway just for (my version) of 'fun'! May be different in the Porsche for some reason, or I may be misunderstanding entirely, but keen to rectify that if it is the case It's about the role the synchro plays in smoothing out the gear change. If it's worn, it can cause a crunch/grind when changing gears using the clutch. When you remove the clutch from the equation, the shift must be perfectly rev matched or else the driver will be unable to select the gear. If the crunch/grind is not present, you can fairly estimate that the synchro is worn and that the gears themselves are working OK. If the crunch/grind is still present, even without using the clutch and perfectly rev matching, then the gear itself is likely damaged. 1 Link to comment Share on other sites More sharing options...
zcacogp Posted August 20, 2021 Share Posted August 20, 2021 On 17/08/2021 at 20:58, Aaron said: It's about the role the synchro plays in smoothing out the gear change. If it's worn, it can cause a crunch/grind when changing gears using the clutch. When you remove the clutch from the equation, the shift must be perfectly rev matched or else the driver will be unable to select the gear. If the crunch/grind is not present, you can fairly estimate that the synchro is worn and that the gears themselves are working OK. If the crunch/grind is still present, even without using the clutch and perfectly rev matching, then the gear itself is likely damaged. Thank you. I've just learned something! Link to comment Share on other sites More sharing options...
extanker Posted August 20, 2021 Share Posted August 20, 2021 always use the clutch.......your wallet and transmission will both be happy 1 Link to comment Share on other sites More sharing options...
SarlechS Posted September 17, 2021 Share Posted September 17, 2021 i had this issue in my Integra Type R (DC2) some gearboxes are very sensitive to new oils. I ended up swapping it out with Amsoil MTF and it fixed all the crunching i was getting before. Link to comment Share on other sites More sharing options...
Hunter Posted September 17, 2021 Author Share Posted September 17, 2021 Yeah, seems to be subsiding now the oil has been in a while. It "went" a couple more times after this post, but I've now not had it crunch for 2 weeks. Fingers crossed I can forget about it now... For the next 12 year service cycle, anyway. Link to comment Share on other sites More sharing options...
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