5th gear "crunching" with shift

Alchemy · 01-23-2012, 08:51 AM

Quote:

Originally Posted by phunk

^^^ absolutely correct. skipping gears is greater wear on the synchros, especially big skips like 2nd or 3rd to 6th... 5th and 6th gear are probably just single brass synchros and are not going to tolerate it long before getting hard to shift into or crunching/scratching in... especially if you try to shift it at a normal shift speed versus doing it slow and letting the synchros slow it down and the rpms fall closer to match.

HMMMM, never knew it was that bad. You learn something new everyday.

LafitteZ · 01-23-2012, 02:20 PM

Im on my second tranny and the first was the same thing grinding from 4th to 5th and thats when my car was na. Now Im forced induction and the second one is doing the exact same crap. I want someone to figure out a way to beef these trannys up. this is getting aggravating. Had a boosted auto 350z with no problems makes me wanna go that route again next time.

Jsolo · 01-23-2012, 03:44 PM

Quote:

Originally Posted by jay4500

It cannot be less wear on the synchronizer; your shifting out of sequence and the 370z transmission has closed gear ratios, so you're causing more stress on the synchronizers. I am a mechanic and I have seen many people damage transmissions with mis-shifts and shifting out of sequence.

Please elaborate. If the revs are proper for the gear/speed, what difference does it make if you skip gears or not?

Double clutching might be helpful too.

Spikuh · 01-23-2012, 06:27 PM

Quote:

Originally Posted by phunk

^^^ absolutely correct. skipping gears is greater wear on the synchros, especially big skips like 2nd or 3rd to 6th... 5th and 6th gear are probably just single brass synchros and are not going to tolerate it long before getting hard to shift into or crunching/scratching in... especially if you try to shift it at a normal shift speed versus doing it slow and letting the synchros slow it down and the rpms fall closer to match.

Quote:

Originally Posted by jay4500

It cannot be less wear on the synchronizer; your shifting out of sequence and the 370z transmission has closed gear ratios, so you're causing more stress on the synchronizers. I am a mechanic and I have seen many people damage transmissions with mis-shifts and shifting out of sequence.

If you guys don't mind elaborating some more on this, I would appreciate it. I was under the impression that so long as the components were spinning at the proper RPM's any extra stress should be negligable. However, I am assuming that no quick-shifting or forcing the transmission into gear is involved.

phunk · 01-24-2012, 01:54 PM

basically you just have to consider what your current engine speed is versus what the engine speed will be once you are completed with the gear change. the further the difference is, the more work the synchros have to match up the shaft speeds. the faster you perform the shift, the less time you are giving the synchros to accomplish this task. also, the faster you perform this shift, the less amount of time you have given the engine rpm to fall closer to the next gear speed.

the wear saved on the clutch by skip shifting is extremely neglible. personally, i would would rather take the very minor extra clutch wear, than add work for the synchros... because of course the clutch is a consumable item already. wearing on the synchros is risky because if they dont fail while youre still in warrenty, than the new transmission is out of your pocket.

but on the other hand, a new transmission for these cars is not as expensive as you may think. i know 350z trans are well under 2000$ and i bet the 370z trans doesnt cost any more, but i havent looked it up. $2000 isnt much considering what a nice clutch/flywheel kit costs. and if you only have to replace the trans every 5 years or so, its not that bad.

but you can replace the transmission all you want, after some time has taken place, they will always start giving you crap into 5th and 6th gear as the synchros are not very robust in those gears, and skip shifting isnt going to do them any favors.

I wouldnt worry about it a whole ton... but if you skip shift nearly every time you take off from a light, you may want to put some consideration into double clutching and/or doing it less often.

jay4500 · 01-24-2012, 02:01 PM

well said.

Spikuh · 01-24-2012, 03:47 PM

Thanks for the information phunk. That is something I need to remember in the future and see if I should change my driving style again. As it stands, I prefer to go 2 - 4 - 6 while shifting around the 2200 mark for most of my daily driving since there is no real need for quicker acceleration and rowing through all the gears only to be stopped a mile down the road is annoying.

phunk · 01-24-2012, 04:39 PM

taking off in 2nd gear isnt very friendly on your clutch!!!!

funny short story... when i was 15, before i had any idea how anything in a car worked, and was learning to drive stick in a friends almost new mitsubishi eclipse... once i got a little comfortable i thought i would challenge myself and start out in 5th gear. i succeeded on the first try... of course she had to replace her clutch 2 weeks later. oops

Spikuh · 01-24-2012, 04:46 PM

Sorry, guess I should have mentioned I launch in 1st, but then 2 - 4 - 6.

RN SHARK · 01-24-2012, 08:33 PM

I've got 22,000 miles on my car and have noticed that crunching from 5th to 6th from time to time, usually before the car really warms up. I think I'll make an appointment with the dealer soon.
Oh, wait, maybe I'll teach my fiance how to drive a manual first, then take it in so she doesn't destroy my new tranny.

ZOperaMan · 01-25-2012, 11:04 PM

Quote:

Originally Posted by jay4500

whats the benefit or purpose of shifting from 3th straight to 5th or 2nd straight to 5th gear. I can see skipping gears on a down shift but cannot understand skipping on up shifts.

No competitive benefit - the occasion where I did this was a brisk romp for the first two gears, then noticing that I was well in excess of the speed limit in second, so I let way off the throttle and tried to find 5th for a cruise gear. Only found the grind.

--ZOM

ZOperaMan · 01-25-2012, 11:15 PM

Quote:

Originally Posted by phunk

...but on the other hand, a new transmission for these cars is not as expensive as you may think. i know 350z trans are well under 2000$ and i bet the 370z trans doesnt cost any more, but i havent looked it up. $2000 isnt much considering what a nice clutch/flywheel kit costs...

As I recall, the price printed on my work order for the part was $2666.

1slow370 · 01-25-2012, 11:22 PM

back in 09 mine was 3200looks like the tsunami freed up some trannies

ZOperaMan · 01-25-2012, 11:23 PM

Quote:

Originally Posted by 1slow370

back in 09 mine was 3200looks like the tsunami freed up some trannies

I suspect that was dealer cost, since it was warranty work.

--ZOM

1slow370 · 01-26-2012, 12:43 AM

yep

Edit: also makes me wonder if half of nissans synchro problems are caused because the gear assembly is so over built it has excessive input shaft inertia, i mean they had to throw a triple cone ductile first synchro in to keep it from dying for gods sake

01-24-2012, 01:54 PM	#125 (permalink)
phunk A True Z Fanatic Join Date: Mar 2009 Location: Chicago Posts: 3,668 Drives: 370 Rep Power: 974723	basically you just have to consider what your current engine speed is versus what the engine speed will be once you are completed with the gear change. the further the difference is, the more work the synchros have to match up the shaft speeds. the faster you perform the shift, the less time you are giving the synchros to accomplish this task. also, the faster you perform this shift, the less amount of time you have given the engine rpm to fall closer to the next gear speed. the wear saved on the clutch by skip shifting is extremely neglible. personally, i would would rather take the very minor extra clutch wear, than add work for the synchros... because of course the clutch is a consumable item already. wearing on the synchros is risky because if they dont fail while youre still in warrenty, than the new transmission is out of your pocket. but on the other hand, a new transmission for these cars is not as expensive as you may think. i know 350z trans are well under 2000$ and i bet the 370z trans doesnt cost any more, but i havent looked it up. $2000 isnt much considering what a nice clutch/flywheel kit costs. and if you only have to replace the trans every 5 years or so, its not that bad. but you can replace the transmission all you want, after some time has taken place, they will always start giving you crap into 5th and 6th gear as the synchros are not very robust in those gears, and skip shifting isnt going to do them any favors. I wouldnt worry about it a whole ton... but if you skip shift nearly every time you take off from a light, you may want to put some consideration into double clutching and/or doing it less often. __________________ Charles @ CJ Motorsports : Website \| Facebook \| Instagram \| YouTube Home of the 9 second, stock longblock, stock drivetrain 6MT 370z. 9.91 @ 142mph

01-24-2012, 02:01 PM	#126 (permalink)
jay4500 Base Member Join Date: Apr 2011 Location: HOUSTON Posts: 47 Drives: 2011 nissan 370z sp Rep Power: 14	jay well said.

01-24-2012, 04:39 PM	#128 (permalink)
phunk A True Z Fanatic Join Date: Mar 2009 Location: Chicago Posts: 3,668 Drives: 370 Rep Power: 974723	taking off in 2nd gear isnt very friendly on your clutch!!!! funny short story... when i was 15, before i had any idea how anything in a car worked, and was learning to drive stick in a friends almost new mitsubishi eclipse... once i got a little comfortable i thought i would challenge myself and start out in 5th gear. i succeeded on the first try... of course she had to replace her clutch 2 weeks later. oops __________________ Charles @ CJ Motorsports : Website \| Facebook \| Instagram \| YouTube Home of the 9 second, stock longblock, stock drivetrain 6MT 370z. 9.91 @ 142mph

01-24-2012, 08:33 PM	#130 (permalink)
RN SHARK Track Member Join Date: Jun 2011 Location: Wake Forest, NC Age: 44 Posts: 618 Drives: 09 370Z, 14 SRT GC Rep Power: 35	I've got 22,000 miles on my car and have noticed that crunching from 5th to 6th from time to time, usually before the car really warms up. I think I'll make an appointment with the dealer soon. Oh, wait, maybe I'll teach my fiance how to drive a manual first, then take it in so she doesn't destroy my new tranny. __________________ ___________ '09 6sp/Z1/PowerTrix/SPL/Swift/SRP/Whiteline/F.I.LTH&CBE/UpRev by Seb/CJM/Stillen/Ings+1/RJM/TrackSpec/Sparco/Motul/Wavetrac/Coolerworx/Verus/CraftSquare '14 SRT Grand Cherokee; '08 TL Type-S

01-25-2012, 11:22 PM	#133 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	back in 09 mine was 3200looks like the tsunami freed up some trannies __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50

01-23-2012, 02:20 PM	#122 (permalink)
LafitteZ Track Member Join Date: Jan 2011 Location: lafitte, la Posts: 698 Drives: 40th anniversary Rep Power: 15	Im on my second tranny and the first was the same thing grinding from 4th to 5th and thats when my car was na. Now Im forced induction and the second one is doing the exact same crap. I want someone to figure out a way to beef these trannys up. this is getting aggravating. Had a boosted auto 350z with no problems makes me wanna go that route again next time.

01-24-2012, 03:47 PM	#127 (permalink)
Spikuh A True Z Fanatic Join Date: Jul 2009 Location: The Ark Posts: 2,357 Drives: '09 370z Rep Power: 21	Thanks for the information phunk. That is something I need to remember in the future and see if I should change my driving style again. As it stands, I prefer to go 2 - 4 - 6 while shifting around the 2200 mark for most of my daily driving since there is no real need for quicker acceleration and rowing through all the gears only to be stopped a mile down the road is annoying.

01-24-2012, 04:46 PM	#129 (permalink)
Spikuh A True Z Fanatic Join Date: Jul 2009 Location: The Ark Posts: 2,357 Drives: '09 370z Rep Power: 21	Sorry, guess I should have mentioned I launch in 1st, but then 2 - 4 - 6.

01-26-2012, 12:43 AM	#135 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	yep Edit: also makes me wonder if half of nissans synchro problems are caused because the gear assembly is so over built it has excessive input shaft inertia, i mean they had to throw a triple cone ductile first synchro in to keep it from dying for gods sake __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50 Last edited by 1slow370; 01-26-2012 at 12:46 AM.

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