R180 installed, but howls

[rayaapp2]

So I blew my old 180 out not long ago.

 

I found this R180 with 4.11 gears in it and a welded carrier. It was dirt cheap so I dont mind if there is something wrong with it.

 

When I get the car up to speed it howls from the the new rear end when I am on the pedal. When I let off the pedal the howl goes away. By howl I mean loud howl btw. So my guess is that I have a Nissan Pickup 4X4 front differential that has been welded and the reverse cut gears are making the noise. The seller wasnt sure what it came out of, but it felt like there was very little play in it before I installed it. It had a little play, but much less than others I have seen. So now Im curious if reverse cut gears would howl like this and there isnt something else more serious going on? And if it does have reverse cut gears then where does that put me with this thing? Its gotta come back out again when I get the new carrier anyway, but if the gears are reverse cut then I have to wonder about loading and on the back of the gear teeth and such. Ive seen Datsun guys install those reverse cut gears in prety much stock datsuns without much of an issue. I never heard of them making a howling noise before, but it would make sense to me that they would. Should I be on the hunt again for correctly cut gears in 4.11 if I want to put 200ft/lbs of torque out the rear?

 

Thanks for input guys and gals

 

 

Ray

[johnc]

I've run those and the 4.38 front truck R180s and never had a howling problem. I don't think Nissan made a special gear cut for those units because the expected time actually engaged would be small. Remember, those trucks had locking front hubs so the axles would free wheel when in 2WD.

[rayaapp2]

sigh,

 

Well then there must be another issue at work here. Oh well I didnt pay that much for it.

 

Thanks John

[johnc]

Check to make sure your diff mounts are good, add some 80W/140 gear oil, and drive it 'till it blows.

[rayaapp2]

Check to make sure your diff mounts are good, add some 80W/140 gear oil, and drive it 'till it blows.

 

I replaced the front mount. The mustache bar had worn bushings esp on the drivers side. I have a set of energy bushings for it on the way, but in the mean time I have it mounted with R200 top and bottom bushings to keep it secure. It doesnt clunk like before so I assume its tight for now. I knew I was going to have to take it back apart. I had to drive it yesterday so I made sure I had it temporarily band aided. All I can think of is that the pinion shaft must have enough play to oscillate at a certain speed. It wont be together like this for long. All I can say is I dont know how track drivers get around corners with a setup like this. As much as the local track drivers rage about welded difs being better for track use, but unusable on the street goes I dont believe it. My other Z has the clutch LSD in it and its far superior from what I can tell. The more traction I can get down from all four tires the better. I did not expect to run the welded one for very long, but dang. I can feel a loss of traction even in high speed cornering. So I guess in the next couple of weeks when I get a chance to put the bushings in I will be setting up the gears as well.

Edited May 4, 2011 by rayaapp2

[johnc]

A LSD is better then a welded diff and a welded diff is better then an open diff. At track speed and with the right suspension setup you don't notice the welded diff. Its driven with a loose rear setup. You come into the corner, trail brake to get the back end rotating, and then slap the throttle down and steer out of the corner with the throttle. It can get hard on rear tires which tend to go away towards the end of the race.

[JMortensen]

Welded diffs are popular with racers because of cost. If you need several different ratios for different tracks, welding costs several dollars, and LSD's for 3 or 4 diffs might cost thousands.

 

John is right that they didn't do reverse cut gears for the front R180s, it's just the same diff flipped around and put in the front end driven backwards. Sometimes weird stuff happens to front diffs on 4x4s, like they get water in them when a car is 4 wheeling and then the water isn't drained out. The rear boils off the water quickly as the car is driven, and the front doesn't because it isn't moving unless the transfer case is engaged, and that causes bearing damage. Things like that. On the other hand, most front diffs have very little use, so if they don't have that oddball damage, they're usually in like new shape.

 

I'd open that one up and have a look at the ring and pinion and the bearings and see if you can easily tell what the problem is, check backlash too. If it looks OK and backlash is in spec, then I would probably try to find another diff. You'll likely spend more trying to figure that one out than you will just buying another one. I think it is unlikely that the pinion is loose, as that would likely cause very severe problems in a short period of time.

 

You can get the K series 4.11 R180 out of the later 240SXs and they're pretty easy to find from what I understand. BJ Hines supplied info on how to convert them from clip in axles to bolt in axles for the big diff thread here: http://forums.hybridz.org/index.php/topic/49194-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount/

[Savage42]

OK, here is a "cheap fix" that has worked in the past and is only recommended and should be done with an open or welded diff, NOT an LSD. (you will figure out why)

 

I had a friend who had a howling diff in his 510 wagon, which has an axle, but still the same issue. My guess is that there is a weird wear pattern on the gears from either dirty/old gear oil, maybe water did get in it as mentioned previously (causing wear) or they ran it low on oil. In any case, you probably have a resonate vibration when the gears mess due to an imperfect wipe area. So, my buddy decided to go get a bottle of Slick 50. I think we all know the stuff is crap to put in your engine, as it doesn't work like they say, but they have found that getting the teflon into high pressure areas (like the ring & pinion) can actually embed the teflon into the surface of the metal. He put it in the diff, drove around and the howl completely went away. He drove it that way for a long time, as the gear oil and Slick 50 seemed to work well. Of course, I would not want the stuff to get into a clutch type LSD!

 

It's a cheap experiment that worked before and is something you can try, as you really don't have anything to lose at this point, right? Good luck!

Edited May 4, 2011 by Savage42