Driveline Shudder 1600-1800rpm, Help Wanted.

[simpletool]

Hi everyone,

I've just bought a series 2 R33 GTS-T (manual). It has a driveline shudder and audible rattle between 1600 and 1800rpm. Is this common? What sort of things cause this?

It happens in any gear, and seemingly any throttle position (although the noise changes pitch obviously).

I'm unsure as to whether it is gearbox bearings, driveshaft bearings or mounts?

No loud bearing noise with clutch in or out in neutral. Smooth apart from this low rpm shudder.

The car is estimated to have travelled 100-120 000km. Car has 170rwkw and standard type clutch.

Just wanted some inside info before I let the monkeys at it.

[sh@un]

Could just be some low rev transmission 'flaring', which is just an un-avoidable occurance in heavy duty drivetrains, due to the larger clearances required (to allow for metal expansion when being worked hard).

But then again, you may well have some bearing(s) on the way out in the g/box or diff, or maybe someone rebuilt the diff at some stage and set the teeth lash or bearing preload up wrong.

If it's the former, it should be better in 1st than 2nd (and I'm assuming you don't drive down at 1600rpm above 2nd gear, yeah?)

[simpletool]

Thanks R32R, it seem like it's coming from gearbox....but hard to tell with these things...since they're all joined.

It's nothing severe......I'm thinking a loose/busted mount causing a bigger rattle than standard.

And yep I drive around 1700-1800 in 3rd and 4th in traffic and really light throttle. Not labouring engine.

Driveline rattle kind of reminds me of AE86 actually.....that used to do a similar thing.

[chiksluvit]

Sorry for digging up an old thread, I have simillar problem with my current R33, I've done a search and it seems like there are diverse opinions on this according to other threads

some says bearings, some say uni joint, some says gearbox internal, some says diff, and some says its exhaust.. it sounded simillar to rattling heatshield but I dont have any heatshield on the exhaust.

However, it seems like the uni joint had the highest vote in this, but there is another member who experienced the same problem said it isn't uni.

so what can it be?!

It only occurs between 1500~2000 on mid-high load, and also makes the interior rattle when this happens.

Has anyone had the same problem and got it fixed?

I did notice a mate's R33 made the same noise too but definitely nowhere near as loud as mine, my old R33 didnt have that problem. But he reckons its the exhaust

I tried 2 exhausts and it didn't affect noise, so I kind of doubt it.

other info on my car:

I have some sort of aftermarket clutch put on by the previous owner, heavy-ish compared to standard clutch, but its pretty easy to use, engagement is like cushion button or standard organic clutch. So I doubt its the twin plate rattle.

gearbox works fine, no crunches, a little notchy when cold, smooth when warm, no problems with reverse gear either

another related thread:

http://www.skylinesaustralia.com/forums/Vi...l=gearbox+noise

[simpletool]

MY thinking (which might be wrong) is that if it happens at same rpm in different gears then it must be gearbox related and on or before the input shaft - since output shaft is at road speed and input shaft is at engine speed.

It has gotten slowly worse in my gearbox. 2 x gearbox places say it's something to do with my input gears/shaft, but probably not bearings.

[R338OY]

What clutch is it running?

[simpletool]

I think it's an EXEDY heavy duty organic - definitely an organic face anyway. It's time to get a new clutch now, I'll get the gearbox looked at when I do.

[chiksluvit]

hrm.. the e-mail thread tracking sys isn't working too well...

please keep us updated, I did suspect that it was possibly the clutch so see how we go there..

your theory does make really good sense, however there are still a few people who also mentioned driveshaft/uni which I guess is also worth looking into.

cheers

Edited July 6, 2009 by chiksluvit

[simpletool]

My logic says next to zero chance of diff/uni-joint beging the issue. Mine is clearly engine RPM dependent - which the uni joint and diff do not see.

[simpletool]

In the name of science I am putting Nulon 85w-140 gearbox oil in my car to see if the thicker oil makes a difference to the vibration and the (very new) crunches in 2nd and 3rd.

At least I'll be able to report if indeed it still changes gears at all - I'll keep you all posted on this.

I am trying this as the crunching only happens when the gearbox is warm and therefore the viscosity is lower. Therefore I am starting with a more viscous fluid and hopefully it might cure some rattle/vibration along the way due to higher film strength. But who knows unless you try.

Currently it has Redline MT90 in it for the past 60,000km it has worked quite well.

[mark33gtst]

Mine was like this... Was the input shaft bearing...

[chiksluvit]

Mine was like this... Was the input shaft bearing...

it sounded like some kind of metallic rattle, like heat shield rattle, and when it happens it only happens on low rpm say 1300~2000, medium-high load, and doesnt really do it when the load is low? (RPM/load dependent)

sorry i just had to ask to make sure since rebuilding/buying new gearbox is the last thing i wanna do...

Edited July 6, 2009 by chiksluvit

[Bass Junky]

If it's any gear, and load, it sounds like you have a light weight flywheel.

Mine has done that since the lightweight flywheel went in 4 years ago.

Mine does it at about 1800 rpm.

[chiksluvit]

thanks..

will also keep that in mind when I change clutch..

[simpletool]

Put the 85w-140 Nulon gearbox oil in today. First few changes from cold are a bit notchy but nothing too bad at all. Then the shift feels as smooth as the Redline MT-90 I had in it for the past 60,000km. The gearbox is definately a bit quieter both at idle and running. The vibration at 1700 to 2000 is reduced and is over more narrow rev range now too.

The shift feel is really good, not notchy at all, after a minutes drive or so. Syncho noise has not appeared at all, and there is no grind or clunck when changing. It feels really good actually - apart from a slight whine noise when I first started it tonight.

Tonight on the 2nd drive it did make a bit of a strange whine noise a couple of times for several seconds during the first 2 minutes of driving - the gearbox oil would have been cold on a cold night like tonight.

I've done about 30km in it so far over 2 drives. We'll see how it goes over the weekend. Certainly the oil might be a touch too thick to protect the gears during the first few minutes so I'll have to put no load on it for the warm-up but I'm usually very careful for the first 2 or 3 minutes anyway.

Edited July 10, 2009 by simpletool

[battery]

damn rb25 drivers!! once im out of first gear the car never goes under 2k rpm struggles way too much down there!

[SkyHi_33]

hmm very interesting, ive had my manual conversion done last week and am experiencing the same thing.

i really do not think that its something to do with bearings or gears as otherwise it would be doing it at all times... had the throw out bearing replaced and everything checked out, was all fine. Really curious as to what it is, keep us posted

Edited July 10, 2009 by SkyHi_33

[chiksluvit]

my friend reckons its worn clutch.

I know my clutch and release bearing are a bit worn, although not slipping yet.

His R33 also made the same noise as my car when it had worn clutch, changed clutch yesterday and no more noise...

[simpletool]

Well the synchro type crunch has gone but the oil is too thick. It has a noticeable but not too loud whine occcasionally for the first few mins. I'm sure it's due to the high viscosity near cold.

I think the crunch/grind I got when I had MT-90 in it was because it was too thin at high temps. It only happened once warm - after at least 30mins of driving. I'm not sure of a typical gearbox temp for town driving (no traffic) after 40mins but I'll guess 60 Celsius. MT-90 is rated as Cst 90 @40C and 15@100C. And once it's used this drops a bit. So I think the oil was too thin for my worn gearbox.

So I've done a little excel spreadsheet which is an APPROXIMATION - should be attached. I have made some assumptions about required viscosity and coloured in squares that are too thin(hot) or too thick (warm).

As you can see the viscosity of the 85w-140 gets REALLY thick as the temp drops below 40 degrees - I guess this makes the whine due to lack of oil flow. I really don't need it this thick.

The oil prevents shifting only at very cold - I can't get 2nd gear easily for about 1 minutes on a winters morning so thick viscosity causes a whine before it affects my ability to shift. The whine is there for another 2 or 3 minutes from cold.

I just want it a bit thicker than 75w-90 so it resists the assumed problem of used MT90 being too thin at around 60 celsius (the actual temp is somewhat irrelevant in this case).

So the Redline 75w-140NS looks good (at an expensive price if it doens't solve the problem), but since this might not be the solution I'm going to blend 1L of Nulon 85w-140 with 3L of Nulon smooth shift 75w-90 to make it a touch thicker. See excel sheet.

We'll see how this goes.

[simpletool]

I put in the Nulon smooth shift 75w-90 with just under a 1L of the 85w-140 that was in the gearbox for a few days. Shift is perfect - no synchro crunches so far. But I'm not so sure it has really solved the synchro problem - I'm waiting for it to appear.

Anyway, if it does turn out to be a problem I am most likely going to get a brand new gearbox from just jap.

Edited July 14, 2009 by simpletool