Maxima Forums - View Single Post - MAINTENANCE and MECHANICAL Information- Don't Post Questions Here! (UPDATED)

*dgeesaman* · 06-21-2007, 04:17 PM

This Q/A applies to manual transmissions only.

What gear oil should I use? How much?

Ideally you should use a 75w-90 weight gear oil rated to GL-4 specifications only. The transmission is designed to shift with GL-4 oil, so using GL-5 or GL-4/GL-5 oil can reduce shifting performance. GL-4 Synthetics like Redline MT-90 or Amsoil MTG are best. You will need 4.5 qts to completely fill the tranny.

To drain the old oil, start by loosening the refill plug first - read 2 paragraphs down. Use the small bolt with 12mm head to drain the tranny. It is located near the rear of the tranny case, facing the center of the car, about 4" forward of the rubber accordian boot at the back of the tranny.

If you choose to drain by removing the gear position sensor (big black plastic thing on the driver's side), be *very* careful not to crack it. Start by rotating it in the bore before very carefully prying it out around the perimeter. Oil will gush out, so be ready with a large, deep catch pan. The oil also stinks.

Refill plug is the big plug directly under the battery. Loosen this plug with a 1/2" square socket wrench and fill to the bottom of this opening with the car level. A funnel on a flexible tube works well for the filling. Make sure the oil is at least room temperature so that it pours faster. Be smart and remove the fill plug BEFORE removing the drain plug.

My axle seal is leaking.

You can replace the seal, but be warned that another reason for leakage at the axle seal is differential carrier bearing wear. The differential is located in the transmission right between the axles, and each axle is fitted into the differential. If the bearings wear out, the differential will become loose inside the transmission and the looseness will cause oil to leak through the seals, even if the seals are new.

Perform this test to check for diff carrier bearing wear:
- under the car, hold the big axle stub at the inner end of the axle. Lift this up and down, looking for any motion of the differential inside the transmission. If your bearings are good, there will be no motion except a *very* slight play between the axle and differential.
- or with the axle pulled, insert a clean, sturdy bar or rod and pry the differential in different directions. If you can make the differential move inside the tranny at all, the bearings are shot.

Why does my tranny grind when I shift?

First check that the oil is properly filled and has been replaced in the last 60k/5 years. For many, using a good gear oil will make enough difference.

Also do not force the tranny into gear or try to shift faster than necessary and be sure the clutch pedal is all the way down until it's in gear. In most cases, taking an extra fraction of a second to complete the shift makes a big difference.

If the grind occurs in more than one gear, be sure your clutch is fully disengaging and operating properly.

If that is good, then you probably have wear on the synchros and gear shifter teeth. Be warned that while changing the synchros will help with the shifting, most rebuilders will not replace the shifter rings and gears due to cost. To completely solve the problem, new gears, shifter rings, and synchros are usually required. This can make rebuilding a tranny more costly in some cases than buying a new(er) unit.

What is a tranny rebuild?

At a minimum, a manual transmission rebuild involves replacing all bearings and seals in the transmission. The transmission is fully disassembled, cleaned, and reassembled with new parts as required. Synchros, gears, slider rings, and shafts are other common parts that get replaced. The spacer shims are adjusted if required.

Note that replacing the hard parts can get very expensive. I suggest agreeing with your rebuilder to agree upon a cost at which they will call for your approval to exceed. If a gear pair or shaft needs replacement the costs can add up quickly.

If you have your tranny rebuilt, be sure to require that the rebuilder *measure* the endplay of the shafts, particularly the differential. If a different spacer shim size is required, it can take a while to get the proper shim sizes from Nissan so plan accordingly. These shims are critical for the rebuilt bearings last longer than the original. Cheap/lazy shops will re-use the shims without measuring to save time and labor.

How do I know if my tranny needs rebuilt?

Rough shifting, worn bearings (often discovered by the axle seal oil leak), noisy bearings. If you have any doubt take it to a tranny rebuilder and have them test or inspect the car.

When you drain your tranny oil, inspect it for fine metal flakes. Spread a little bit on your fingertip and hold it under a bright light. Silver metal flakes indicate substantially worn bearings and need for a rebuild. Gold metal flakes suggest synchro damage.

If you have your transmission removed from the car, or a used transmission ready to be installed, I highly recommend paying a tranny shop an hour of labor to open and inspect it before installing. This is the best way to assess the condition of your tranny, and if there is work to be done, provides the most accurate and lowest cost estimates.

I hear a bearing noise. Is it my clutch throwout bearing or a tranny bearing?

Bearing noise is typically a growling, rolling, or whining noise coming from the engine bay on the drivers side.

Tranny input shaft bearings tend to make noise when the clutch is out and the tranny is in neutral. Throwout bearings tend to make noise when the clutch is engaging or disengaging, but not when the tranny is in neutral. The other tranny bearings usually don't make any sound. The throwout bearing is not inside the tranny, so it doesn't require a rebuild to replace it, but it still requires removing the tranny.

What is VLSD and how much better is it?

VLSD stands for Viscous Limited Slip Differential. The other type is an open differential. Open differentials will freely allow the two front wheels to rotate at different speeds, in fact if the front wheels are off the ground, rotating one wheel will cause the opposite wheel to rotate in the opposite direction.

VLSD keeps both wheels spinning in the same direction and provides some resistance when they are rotating at different speeds.

The big difference in driving is that if one wheel loses traction, an open differential will spin that wheel. In a VLSD, it will not spin a wheel until both wheels are closer to the threshold of sliding, thus providing more grip and better control. This is useful both on dry pavement and in slick conditions. The VLSD was standard equipped on many Canadian models for it's winter weather benefits.

Can I install a 6 speed?
Yes, but it requires modification to the shifter. The 4th gen manual transmission is shifted using a lever, and the 6 speeds found in the later Maximas are shifted by cable. While it is not impossibly complicated, it is not a direct bolt-in.

How to REBUILD 5speed transmission
http://forums.maxima.org/showthread....00#post6215300

06-21-2007, 04:17 PM	#56
dgeesaman Maintenance Monster Join Date: Jul 2001 Location: Harrisburg, PA iTrader: (5) Posts: 3,138	Manual Transmission FAQ This Q/A applies to manual transmissions only. What gear oil should I use? How much? Ideally you should use a 75w-90 weight gear oil rated to GL-4 specifications only. The transmission is designed to shift with GL-4 oil, so using GL-5 or GL-4/GL-5 oil can reduce shifting performance. GL-4 Synthetics like Redline MT-90 or Amsoil MTG are best. You will need 4.5 qts to completely fill the tranny. To drain the old oil, start by loosening the refill plug first - read 2 paragraphs down. Use the small bolt with 12mm head to drain the tranny. It is located near the rear of the tranny case, facing the center of the car, about 4" forward of the rubber accordian boot at the back of the tranny. If you choose to drain by removing the gear position sensor (big black plastic thing on the driver's side), be very careful not to crack it. Start by rotating it in the bore before very carefully prying it out around the perimeter. Oil will gush out, so be ready with a large, deep catch pan. The oil also stinks. Refill plug is the big plug directly under the battery. Loosen this plug with a 1/2" square socket wrench and fill to the bottom of this opening with the car level. A funnel on a flexible tube works well for the filling. Make sure the oil is at least room temperature so that it pours faster. Be smart and remove the fill plug BEFORE removing the drain plug. My axle seal is leaking. You can replace the seal, but be warned that another reason for leakage at the axle seal is differential carrier bearing wear. The differential is located in the transmission right between the axles, and each axle is fitted into the differential. If the bearings wear out, the differential will become loose inside the transmission and the looseness will cause oil to leak through the seals, even if the seals are new. Perform this test to check for diff carrier bearing wear: - under the car, hold the big axle stub at the inner end of the axle. Lift this up and down, looking for any motion of the differential inside the transmission. If your bearings are good, there will be no motion except a very slight play between the axle and differential. - or with the axle pulled, insert a clean, sturdy bar or rod and pry the differential in different directions. If you can make the differential move inside the tranny at all, the bearings are shot. Why does my tranny grind when I shift? First check that the oil is properly filled and has been replaced in the last 60k/5 years. For many, using a good gear oil will make enough difference. Also do not force the tranny into gear or try to shift faster than necessary and be sure the clutch pedal is all the way down until it's in gear. In most cases, taking an extra fraction of a second to complete the shift makes a big difference. If the grind occurs in more than one gear, be sure your clutch is fully disengaging and operating properly. If that is good, then you probably have wear on the synchros and gear shifter teeth. Be warned that while changing the synchros will help with the shifting, most rebuilders will not replace the shifter rings and gears due to cost. To completely solve the problem, new gears, shifter rings, and synchros are usually required. This can make rebuilding a tranny more costly in some cases than buying a new(er) unit. What is a tranny rebuild? At a minimum, a manual transmission rebuild involves replacing all bearings and seals in the transmission. The transmission is fully disassembled, cleaned, and reassembled with new parts as required. Synchros, gears, slider rings, and shafts are other common parts that get replaced. The spacer shims are adjusted if required. Note that replacing the hard parts can get very expensive. I suggest agreeing with your rebuilder to agree upon a cost at which they will call for your approval to exceed. If a gear pair or shaft needs replacement the costs can add up quickly. If you have your tranny rebuilt, be sure to require that the rebuilder measure the endplay of the shafts, particularly the differential. If a different spacer shim size is required, it can take a while to get the proper shim sizes from Nissan so plan accordingly. These shims are critical for the rebuilt bearings last longer than the original. Cheap/lazy shops will re-use the shims without measuring to save time and labor. How do I know if my tranny needs rebuilt? Rough shifting, worn bearings (often discovered by the axle seal oil leak), noisy bearings. If you have any doubt take it to a tranny rebuilder and have them test or inspect the car. When you drain your tranny oil, inspect it for fine metal flakes. Spread a little bit on your fingertip and hold it under a bright light. Silver metal flakes indicate substantially worn bearings and need for a rebuild. Gold metal flakes suggest synchro damage. If you have your transmission removed from the car, or a used transmission ready to be installed, I highly recommend paying a tranny shop an hour of labor to open and inspect it before installing. This is the best way to assess the condition of your tranny, and if there is work to be done, provides the most accurate and lowest cost estimates. I hear a bearing noise. Is it my clutch throwout bearing or a tranny bearing? Bearing noise is typically a growling, rolling, or whining noise coming from the engine bay on the drivers side. Tranny input shaft bearings tend to make noise when the clutch is out and the tranny is in neutral. Throwout bearings tend to make noise when the clutch is engaging or disengaging, but not when the tranny is in neutral. The other tranny bearings usually don't make any sound. The throwout bearing is not inside the tranny, so it doesn't require a rebuild to replace it, but it still requires removing the tranny. What is VLSD and how much better is it? VLSD stands for Viscous Limited Slip Differential. The other type is an open differential. Open differentials will freely allow the two front wheels to rotate at different speeds, in fact if the front wheels are off the ground, rotating one wheel will cause the opposite wheel to rotate in the opposite direction. VLSD keeps both wheels spinning in the same direction and provides some resistance when they are rotating at different speeds. The big difference in driving is that if one wheel loses traction, an open differential will spin that wheel. In a VLSD, it will not spin a wheel until both wheels are closer to the threshold of sliding, thus providing more grip and better control. This is useful both on dry pavement and in slick conditions. The VLSD was standard equipped on many Canadian models for it's winter weather benefits. Can I install a 6 speed? Yes, but it requires modification to the shifter. The 4th gen manual transmission is shifted using a lever, and the 6 speeds found in the later Maximas are shifted by cable. While it is not impossibly complicated, it is not a direct bolt-in. How to REBUILD 5speed transmission http://forums.maxima.org/showthread....00#post6215300 Last edited by dgeesaman; 05-09-2008 at 05:13 AM.