Zfan1 Posted September 20, 2014 Share Posted September 20, 2014 I am trying to find out why the rear diff. is howling on my swapped Broken Kitty L76/4L80E swap. I didn't have any noise at all with my scarab mounted 385 scb/700r4. I know the drive shaft sits at more of an angle than before and is now shorter than before after swapped. The transmission shaft sits lower than before thus causing more of an angle plus the front u-joint is a Spicer type large GM 3150. The rear u-joint is a Datsun/Nissan, much smaller, not sure of actual size. Has anyone done an auto swap with there LS conversion that had howling issues? I have drained and filled the R200LSD with new fluid and Limited slip additive, this did not help at all. My concern is that the u-joints being different sizes may play a role plus the rear diff. sitting so much higher than the transmission is causing too much pinion angle. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 20, 2014 Share Posted September 20, 2014 Every diff I have ever had howled like a werewolf. Quote Link to comment Share on other sites More sharing options...
Mikey303LSZ Posted September 20, 2014 Share Posted September 20, 2014 I used the JCI engine mounts, trans cross member (LS1, 4L60E), JCI drive shaft etc. No driveline alignment issues and no howling rear diff. Can you put the car on a lift, run the car in drive and use a stethoscope to pinpoint the location? Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 20, 2014 Share Posted September 20, 2014 Bad angles cause vibration, not diff howl. Noise (the howl) transmitted in to the cabin from the diff is usually from the mounts being too solid, allowing a good path for high frequency noise. Is it possible that your propeller shaft is too long for the new setup, pressing the diff back in its mounts? Quote Link to comment Share on other sites More sharing options...
heavy85 Posted September 22, 2014 Share Posted September 22, 2014 (edited) When mine howled so loud you needed earplugs it was pinion bearings. Edited September 22, 2014 by heavy85 Quote Link to comment Share on other sites More sharing options...
Zfan1 Posted September 23, 2014 Author Share Posted September 23, 2014 Going to pick up a digtial angle finder today and find out how many degree's of angle I am looking at and make adjustments. I will also be pulling the driveshaft and have it rebalanced at high speed as it has developed a little bit of vibration. Luckily if there is a serious rear diff. problem I happen to have a spare R200LSD in the garage plus a new set of clutches. Quote Link to comment Share on other sites More sharing options...
Phantom Posted September 26, 2014 Share Posted September 26, 2014 Never had this issue but then I have the torque tube set-up so there is no angle on mine. Sorry, couldn't resist. Quote Link to comment Share on other sites More sharing options...
Zfan1 Posted September 26, 2014 Author Share Posted September 26, 2014 I think the John's Cars LS swap kit lowers the motor from my previous set up (Scarab) and this may just be the culprit. I do not know the exact difference between the two but I will find out tomorrow when I take it to my friends shop and check the driveshaft angles. If it's an inch or two lower that would be huge seeing that the driveshaft is so short. It could change the angle by several degree's. Quote Link to comment Share on other sites More sharing options...
socorob Posted September 26, 2014 Share Posted September 26, 2014 Sure is not your u joints making noise? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 26, 2014 Share Posted September 26, 2014 Never had this issue but then I have the torque tube set-up so there is no angle on mine. Sorry, couldn't resist. Your torque tube should still have some angle on it. The driveshaft needs a bit of angle. If you've taken a U-joint apart, you remember all the needle bearings in there. If you have the driveshaft perfectly inline, then those needle bearings don't spin. What that means is that every time you step on the gas the torque gets transferred through the same needle bearings which never spin. You would quickly wear them out and develop a clunk. Zfan1, as far as measuring the angles goes, an angle measure isn't really good enough. I just went through this myself and posted about it in this older thread: http://forums.hybridz.org/topic/43993-differential-laser-alignment-tool/ I agree with NewZed that driveshaft angles will cause a vibration and not a howl, and with heavy85 that pinion bearings are a likely suspect. Quote Link to comment Share on other sites More sharing options...
Phantom Posted September 27, 2014 Share Posted September 27, 2014 Jon, Yeah, you're right as usual. Ma bad. The torque tube is set up with a slight angle but evidently it's the right one as I've had no issues with howling or vibration. I do get some noise but its always been minimal. Quote Link to comment Share on other sites More sharing options...
Zfan1 Posted September 27, 2014 Author Share Posted September 27, 2014 Well I checked the pinion angle and it was 6.40 degree's...yikes. Got it to 2.70 degree's and still howls and has an ever so slight vibration. No howling in the diff with old set up as I stated earlier but I am guessing it is loading at a different angle so like a member mentioned earlier it could be a bearing or gear issue. I have a spare R200LSD rear diff. so I will put it on the bench and build it with the clutches I picked up in another group buy some time ago. I am also going to take the driveshaft back to Driveshaft King and have them recheck the high speed balance and u-joints while they are at it. I hate that howl enough to not drive the damn car, pardon my French! Quote Link to comment Share on other sites More sharing options...
Zfan1 Posted November 5, 2014 Author Share Posted November 5, 2014 Well I fixed the problem by rebuilding my other R200LSD and swapping rear ends out. Went to the track this past weekend and now it's howling again, guess it did not like the abuse. The good news is my cam only LS2/4L80E combo went a best of 6.71 at 104.50, worse pass was a 6.81 at 103. Still have some tuning to finish but for a stock motor with cam and valve springs that's hauling, love the LS platform! I also scaled the car, 2860 lbs with me in it, I was surprised what the little 240Z weighs. Quote Link to comment Share on other sites More sharing options...
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