Jolt when selecting reverse

[sowlerthjh]

I notice that when I select reverse (soon after starting), and hold the brake pedel down, the car sometimes trys to jolt backwards.

Why is this? and why does this not happen every time?

[QX4ME]

I always feel some degree of jolt. I think it's normal, as the reverse gear is engaged (driver asks it to go backwards). When car is cold I feel a little more.

[Towncivilian]

I feel something similar. Perhaps applying the parking brake before shifting into P when parking can help mitigate this, but probably not. If you are concerned that the jolt is excessive, check your transmission fluid level and condition (see MA-22).

[sowlerthjh]

Thanks for the advice - it is not a massive problem, but I just wondered whether there is a reason why it sometimes does no jolt, and sometimes does a strong jolt.

I shall try applying the parking brake before putting the transmission in park and see if that makes a difference.

[esy]

what are the instances that you feel it and when you don't?

does it vary or is it only during certain instances?

do you feel it randomly when you're shifting in the same exact instances?

[sowlerthjh]

I feel it randomly when I am shifting in the same exact instances.

This is first time in the morning when I select reverse to back out of the garage.

[iceman14n]

its pretty normal, wait till it gets really cold, -40 or so and do that, you'll really feel it then but as the truck warms up, it goes away, you know the gears are kinda stuck together and need some time to warm up so you feel it if you do it as soon as you start the car.

Wow that was a long sentence lol

[iceman14n]

its pretty normal, wait till it gets really cold, -40 or so and do that, you'll really feel it then but as the truck warms up, it goes away, you know the gears are kinda stuck together and need some time to warm up so you feel it if you do it as soon as you start the car.

Wow that was a long sentence lol

[sowlerthjh]

That explains it very well, thanks.

Hopefully, it will not get as cold as -40 since I am based in Dubai!!

[ottofalcon]

mine does it to, but it's quite small, and another thing i notice is if i leave it in auto-mode when i stop and select park after about 20 ish seconds it kinda jolts, like if i where bumped into.
Also if their was some slip detected and the 4wd kicked in and I turn it off when I get to where I'm going their is a small bang, in the front diff, but it only happens when it's in auto not 2wd or lock, everything is working fine, i drove another qx4 and tried this out and the same thing happened only it wasnt as hard as mine did.

[ARKQX33V6]

Possible reasoning when engine is cold is that the engine is enriched to fast idle over 750 RPM and when going into a reverse gear the ratio of reverse is quit high, so you back up at a lower speed but at about 1000-1500 RPM there is a lot of torque in this gear.

Have you ever noticed how much the rear end of the Q lowers when in reverse at high revs, check it out, all that torque must end up or down somewhere.

[sowlerthjh]

Yes, I think the higher revs must be to do with it.

I will look later at how much mine lowers in reverse, but I would not be surprised.

[QX4ME]

Something similar to selecting reverse.

When I stop at a red light, I tried putting in N and back into D. I randomly felt a big jolt, or a very small jolt. Totally random even with the car warmed up. Normally if I tried it back and forth a few times at a same stop, the first time is a big jolt, second time is less, then less and less if I do more times.

The 'best' time is, when I put my hand on the steering wheel and try between D and N, I can feel just a tiny vibration difference. My 00 RX300 has even less of that, or none no matter cold or warm.

[Towncivilian]

How often do you exchange the transmission fluid?

[QX4ME]

I assume you were asking me.
I changed transmission fluid a yeat ago for the first time, at about 78k miles. I checked it every now and then and found no color change, no burnt smell. However, it had been eight years so I changed it. during nine years of normal driving, it has been shifting very smoothly.

[QX4ME]

I assume you were asking me.
I changed transmission fluid a yeat ago for the first time, at about 78k miles. I checked it every now and then and found no color change, no burnt smell. However, it had been eight years so I changed it with Nissan genuine fluid. During nine years of normal driving, it has been shifting very smoothly.

[Towncivilian]

Yep, I was asking you. That sounds reasonable. Have you verified the level is correct? How often do you grease the driveshafts?

[QX4ME]

I remember the level was within the range. I had drave shafts greased a year ago, the same time as the transmission fluid. I had them done by a mechanic, not at the dealer, to save some money. According to the maintenence schedule, I think I need to do more frequently.

[Towncivilian]

You most certainly do. I would grease them at least every oil change. Use any NLGI No. 2 lithium soap base grease. My 2001.5 FSM says NLGI No. 2 lithium soap base containing molybdenum disulphide, but it seems that your 2002 QX4 would do just fine on any generic lithium grease.

[ARKQX33V6]

Moly grease with maintain metal contact at high RPM and the faster you go the faster the shaft spins.

As an aside re: transmission oil changes: Years ago I discovered a change out is a very good thing as it brings unseen particles from within out of the transmission. Driving a vehicle 8-9 years on the same fluid in the transmission is cause for shifting failure, because friction material within the transmission is in very small particles and this material is non ferrous, non metallic but it has the ability to plug up tiny passages and play havoc with hydraulic pressure, thus all aspects of hydraulic action placed upon mechanical gears. Also transmission use transmission fluid because of shear forces within the gear sets, planetary and Sun gears. The speeds of operation mean that oil clings upon the gear set but contaminants within the oil cause the oil to lose adhesion and hydraulic forces need this stick-to-it-ness. Oil is also a lubricating medium. @When this same oil sticks too much the oil is warmed, heated and could become burnt. Burned transmission oil becomes more tarnish sa the chemical changes take place. When the oil goes from a bright red pink to a brown it's too late, the damaged oil is now damaging things that move and don't move.

The transmission is an art form of hydraulics which needs cleanliness above all. A complex gear set with actuators and solenoids and a small computer telling what should take place at what time gets all fouled up with low oil, over-filled oil, burnt oil and oil that is in service too long.

The transmission get very hot, so hot that the transmission cooler is part of the engine cooler. At 180-200 F that is cooler than the transmission, yst that heat exchanger up front is used to cool the transmission oil.

With oil flowing at 200-400 F it soon wears out, yes the oil wears as it gets hot then cold then hot, and the cycle is never ending but the useable life span of the oil is soon ended.

Costs
A transmission tune up is costy and requires down time.
For all you DIY, the cost of a change out is cheaper because you're not paying for labour, the easiest is 4-6 liters or quarts of transmission oil. No filter, no dismantle of the pan. But if this is going to be the first oil change in over 3 years, drop the pan, drop the oil screen, remove all not 4-6 quarts, refill and be very careful that you refill to the exact mark. No under or over allowed. Then get into the habit of doing a partial dump every other year.

Benefits
If you had a temp gauge on the transmission 1st it would shock you as to how hot it gets.
New unused oil has greater lubricity, no matter the grade.
New oil is clean.
New oil can take contamination
The contaminants are in there for max 2-3 years because you drain out whatever is in the sump and that is where the crap settles.
Changed oil can be examined and tested
The valves will operate as they should
Transmission problems will be diminished

If you are having shifting, slamming, hard shifts when warmed you may need technical help but the changing of oil is not a miracle worker, but on the second hand it sure does take most of the problems away about the problems some of you are discussing. The transmission is often forgot about and like the rest of the car PM goes a long way.

[Towncivilian]

An in-line or spin-on filter and an auxiliary transmission cooler also go a long way in preserving both the transmission and the fluid. I run an 13,000 GVW B&M 70268 stacked plate transmission cooler and a Magnefine in-line transmission filter for my R50 which rarely does anything more than light towing. I noticed an improvement in shifting quality within a few thousand miles. I use Valvoline Maxlife ATF, and have done one pan drop & filter change to get rid of accumulated ferrous grime in the pan and on the magnet. The cooler, filter, and extra hose required totaled about $90.

Currently I am about half a quart low from messing around with the new cooler hoses (trying to route them so the stock undercover will go back on). The shift quality suffered noticeably even with a seemingly small amount low. The fluid is visible at the bottom of the dipstick but is not within the notched area at operating temperature after checking per the FSM.

[QX4ME]

I heard flushing transmission fluid is not good; it might cause failure. However, Infiniti dealer who checked the front strut corrosion for me showed me an Infiniti printout saying flushing is recommended. The service advisor also said that starting 2011, Infiniti's transmissions no longer require fluid change.

[Towncivilian]

"Power" flushes are bad. Flushing machines which use no chemicals/cleaners/solvents/conditioners, etc and use solely the transmission's pump to exchange fluids are fine. I believe T-tec machines do such a procedure, but correct me if I'm wrong.

[QX4ME]

This site is great, so many experts for me to learn from.
I am a bit confused with synthetic engine oil. My QX4 has 83K miles. Is it a good thing to start putting synthetic engine oil in? I heard there are two types of synthetic oil, one for newer the other for higher mileage cars, and once synthetic oil is put in, I can't change it back to regular oil, and so on so forth. Also, is there synthetic transmission oil? I'd guess yes but don't have time to go throughh all these things.

Thank you all for any information.

[Towncivilian]

You can switch back and forth between conventional and synthetic oil without issue. If you couldn't, how would one explain the presence of synthetic blend oils, which contain a blend of conventional and synthetic oils in one bottle?

High mileage engine oils do exist, and they generally contain seal "conditioners" which are usually in the form of esters or plasticizers. They seem to "swell" the seals somewhat in order to make them more pliable instead of hard and brittle (at least this is what I've read). HM oils also usually contain more cleaning and anti-wear additives.

You may run synthetic engine oil in your 2002 QX4. For some reason, 2003-2004 Pathfinder owner's manuals state that synthetic oil should not be used. I have not checked the '03 QX4 manual for this clause, but it doesn't matter much either way for you and I, now does it?

Synthetic transmission fluid exists. Valvoline Maxlife is a relatively cheap fluid that works in nearly anything and as I said, I run it and have no issues. Mobil 1 is another widely available alternative (I use M1 ATF for my power steering fluid), and "boutique" fluids such as Amsoil, Royal Purple, Redline, etc are available. The advantage of synthetic transmission fluid is reduced operating temperature and increased resistance to oxidation, and probably a few other points I'm missing.

[jimmymoo]

Which part of drive shaft should I grease with lithium grease? Anyone have pictures? I'm getting the jolt when putting gear in reverse from park as well.

[Towncivilian]

If your QX4 is 4WD, your rear driveshaft won't have a grease zerk; grease the front one instead. If you don't see the zerk, you may have to move the vehicle a few feet to position the zerk facing downward since it rotates with the driveshaft.

You should also inspect the driveshaft carrier bushing for excessive play or wear; this is the big bushing around the middle of the rear driveshaft.

[jimmymoo]

Nice! I'll take a look tomorrow.

Thanks for the help