Must rear diff and MT fluid weight match?

Nismodean · 10-30-2018, 11:25 PM

Starting to develop a 4th gear grind from 3rd to 4th, 5th to 4th is fine. Only happens after the car is fully warmed up. I believe a more viscous MT fluid will rid me of this nuisance, however, I don't want to swap the rear diff fluid to a thicker fluid. Is it recommended or required that those two fluids match in weight?

2011 Nismo#91 · 10-31-2018, 06:46 AM

The MT gear fluid is independent of the Diff gear fluid. The two are not supposed to be the same.

Spooler · 10-31-2018, 08:00 AM

Rear diff fluid is GL-5 and will ruin your synchro's if used in the manual tranny. You need GL-4 fluid for the manual tranny.

JARblue · 10-31-2018, 10:02 AM

The owner's manual specifies different fluids. Why would you think they need to match?

Nismodean · 10-31-2018, 11:20 AM

Weights of fluid, not types. I understand that there's different requirements for both.

BBQdDude · 10-31-2018, 01:28 PM

Possibly a snychro issue for that gear?

SouthArk370Z · 10-31-2018, 02:47 PM

The weights do not have to match. Since they do similar jobs (torque multiplication via gears) under similar loads, the spec'ed weights can be the same ... but they don't have to be.

There are several threads about changing to different trans fluid to help with shifting problems.

Chasingstatus · 10-31-2018, 06:20 PM

Quote:

Originally Posted by Nismodean

Starting to develop a 4th gear grind from 3rd to 4th, 5th to 4th is fine. Only happens after the car is fully warmed up. I believe a more viscous MT fluid will rid me of this nuisance, however, I don't want to swap the rear diff fluid to a thicker fluid. Is it recommended or required that those two fluids match in weight?

Let's start here, have you changed any fluids in the car or had them changed recently? Or are you just starting to develop a grind? To each their own but Nissan's mtf is pretty damn 75w-85 is the weight you should stick with. The grind is independent of your rear differential. So changing the diff fluid won't help you. When was the last time you had the clutch fluid replaced?

Rusty · 10-31-2018, 09:12 PM

You can put any weight in the tranny. Long as it's GL-4. I've see trannies run from ATF to 250w. But remember. The heavier the weight. The harder the shifting. In cold weather. It will be stiffer.

onzedge · 10-31-2018, 11:18 PM

Quote:

Originally Posted by JARblue

The owner's manual specifies different fluids. Why would you think they need to match?

BGTV8 · 11-01-2018, 02:57 AM

^^^^^

What he said

2011 Nismo#91 · 11-01-2018, 11:20 AM

Moving beyond the orginal question. Nissan Synchros in the Z are not all that great for what ever reason, many people have issues with it, a few so bad that they had them replaced under warranty. Personally 4th to 5th is the worst for me. I have to shift slowly to avoid grinding. Odd thing is it never gives me any issue when I am at the track shifting at near red line

.I have changed the gear fluid in the MT to a 50/50 mix of Redline MTL and MT-90, which is now MT-85. I did this to have the transmission shifting feel smoother, it had no effect on the synchros.

10-30-2018, 11:25 PM	#1 (permalink)
Nismodean Enthusiast Member Join Date: Oct 2010 Location: Washington Posts: 313 Drives: 2009 RIP Now 2012 Rep Power: 15	Must rear diff and MT fluid weight match? Starting to develop a 4th gear grind from 3rd to 4th, 5th to 4th is fine. Only happens after the car is fully warmed up. I believe a more viscous MT fluid will rid me of this nuisance, however, I don't want to swap the rear diff fluid to a thicker fluid. Is it recommended or required that those two fluids match in weight? __________________ The Truth, it hurts sometimes. FI LTH & FI CF CBE. This is a 370Z forum, if I want to fling poo at another brand of car and your feelings get hurt, then you're hanging out in the wrong forum (cry elsewhere).

10-31-2018, 06:46 AM	#2 (permalink)
2011 Nismo#91 A True Z Fanatic Join Date: Mar 2011 Location: NJ Posts: 2,401 Drives: slowly Rep Power: 40569	The MT gear fluid is independent of the Diff gear fluid. The two are not supposed to be the same. onzedge and SouthArk370Z like this. __________________ GTR TT 493Whp/431lbft, Ecutek, Southbend 6puck,Quaife, RPM RollBar 4Point, R888R, JRZ RSPro F(10R/10C) R(10R/6C) 1000f500r inlbs+150inlbs Tender, SPL everywhere.Full Specs

10-31-2018, 08:00 AM	#3 (permalink)
Spooler A True Z Fanatic Join Date: Jun 2014 Location: Ga Posts: 13,803 Drives: 2013 Nismo 370z Rep Power: 2684392	Rear diff fluid is GL-5 and will ruin your synchro's if used in the manual tranny. You need GL-4 fluid for the manual tranny. Rusty likes this.

10-31-2018, 10:02 AM	#4 (permalink)
JARblue A True Z Fanatic Join Date: Mar 2011 Location: Austin, TX Age: 43 Posts: 36,450 Drives: 11 Z34, 98 E36 M3 Rep Power: 2684440	The owner's manual specifies different fluids. Why would you think they need to match? __________________ 2011 370Z 6MT Sport Gun Metallic \| ARC \| CJM \| Ecutek \| FI \| Fujimura \| R2C \| SPL \| Stillen \| TWM \| Z1 \| ZSpeed \|

10-31-2018, 11:20 AM	#5 (permalink)
Nismodean Enthusiast Member Join Date: Oct 2010 Location: Washington Posts: 313 Drives: 2009 RIP Now 2012 Rep Power: 15	Weights of fluid, not types. I understand that there's different requirements for both. __________________ The Truth, it hurts sometimes. FI LTH & FI CF CBE. This is a 370Z forum, if I want to fling poo at another brand of car and your feelings get hurt, then you're hanging out in the wrong forum (cry elsewhere).

10-31-2018, 01:28 PM	#6 (permalink)
BBQdDude Base Member Join Date: Aug 2016 Location: Ohio Posts: 122 Drives: 2013 370Z NISMO Rep Power: 9	Possibly a snychro issue for that gear?

10-31-2018, 02:47 PM	#7 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324198	The weights do not have to match. Since they do similar jobs (torque multiplication via gears) under similar loads, the spec'ed weights can be the same ... but they don't have to be. There are several threads about changing to different trans fluid to help with shifting problems. __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

10-31-2018, 09:12 PM	#9 (permalink)
Rusty Ronin Samurai - Assassin Join Date: Dec 2011 Location: Fayettenam,Pennsyltucky Age: 68 Posts: 35,189 Drives: 2011 Nismo GM 6M Rep Power: 2684437	You can put any weight in the tranny. Long as it's GL-4. I've see trannies run from ATF to 250w. But remember. The heavier the weight. The harder the shifting. In cold weather. It will be stiffer. __________________ 浪人 - 殺し屋 "The Difficult Anytime, The Impossible By Appointment Only" http://www.the370z.com/members-370z-...o-journal.html

11-01-2018, 02:57 AM	#11 (permalink)
BGTV8 A True Z Fanatic Join Date: Dec 2009 Location: 03350 Australia Posts: 1,514 Drives: 09 Nissan 370Z M6 Rep Power: 39973	^^^^^ What he said

11-01-2018, 11:20 AM	#12 (permalink)
2011 Nismo#91 A True Z Fanatic Join Date: Mar 2011 Location: NJ Posts: 2,401 Drives: slowly Rep Power: 40569	Moving beyond the orginal question. Nissan Synchros in the Z are not all that great for what ever reason, many people have issues with it, a few so bad that they had them replaced under warranty. Personally 4th to 5th is the worst for me. I have to shift slowly to avoid grinding. Odd thing is it never gives me any issue when I am at the track shifting at near red line .I have changed the gear fluid in the MT to a 50/50 mix of Redline MTL and MT-90, which is now MT-85. I did this to have the transmission shifting feel smoother, it had no effect on the synchros. __________________ GTR TT 493Whp/431lbft, Ecutek, Southbend 6puck,Quaife, RPM RollBar 4Point, R888R, JRZ RSPro F(10R/10C) R(10R/6C) 1000f500r inlbs+150inlbs Tender, SPL everywhere.Full Specs Last edited by 2011 Nismo#91; 11-01-2018 at 11:22 AM.

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