By special request:
From this thread:
http://forums.s2ki.com/forums/showthread.p...threadid=184942

POST ONLY IF YOU KNOW!
Post up what specs were used in your 4.77 installation and how this has worked for you since.
I'll keep this stickied for a "little while" (till people can bookmark it).

 

I set the total preload on my pinion bearings to 12 inch-lbs. This was achieved with the minimum torque on the companion flange nut (95 ft-lbs, I think). This resulted in a minimum preload on the carrier bearings that FAR exceeded the maximum spec. From a mathematical standpoint, I think the Helm's manual specs for carrier bearing preload are impossible to achieve. I wound up preloading the carrier bearings to about 20 lbs (measured as described in the manual). I set the R&P backlash to the minimum spec of about .0025".

It turned out that the 95 ft-lbs on the companion flange nut wasn't even enough to fully seat everything, so the pinion loosened up a lot in the 1st second of my test drive (I could push the companion flange up and down). I had to drop the driveshaft, and increase the torque on the companion flange nut until there was no more play in the pinion. Unfortunately, I can't recall what amount of torque was required to achieve that. I'm sure that changed both preload specs as well, but I don't think it would have changed the backlash.

I did have some high pitched whining for a couple thousand miles, but it went away. It is completely quiet now. I have done 95 hard track miles, and about 30 hard autocross runs without any complications.

 

Stock specs worked like a charm for me.

 

Doesn't seem like much input here. If you know of someone who has 4.77's, please PM a link of this thread to them. Bookmark this thread for your reference and to show others who may ask in future. I'm going to leave this stickied for only a couple weeks longer. We want to keep the "stickied" threads down to a minimum.
Thanks.

 

I just spoke with fperra on the phone about his 4.57 install. He ran into the same issue that I did about the preload on the carrier bearings. He followed the Helm's instructions for setting the preload on the pinion bearings, and came up with 18 in-lbs. The instructions say to measure the torque required to turn the pinion before preloading them (Tp), then tightening the companion flange nut until the preload increases turning torque by an ADDITIONAL 7.8-12.1 in-lbs. The resulting turning torque is Tp + preload. In fperra's case, this meant that the minimum possible push/pull force to turn the LSD would be some multiple of that 18 in-lbs + the preload on the carrier bearings. Assuming the carrier bearing preload is ZERO, then the minimum push/pull force would be (Pinion Turning Force) * (Gear Ratio) / (Ring Bolt Radius)). His gear ratio is 4.57, pinion preload is 18 in-lbs, and the ring bolt radius is 3", so the minimum possible push/pull force to turn the LSD is 27.4 lbs. The book has to be wrong, since it says the push/pull force should be 3.1-6.8 lbs.

Since the pinion preload was set by measuring the turning force before preloading the pinion (Tp), then adding 7.8-12.1 in-lbs, I think the same should be done when preloading the LSD. For example, measure the push/pull force on the LSD without any preload (Tf), then add 3.1-6.8 lbs. In fperra's case, this would be a target push/pull force of 30.5-34.22 lbs.

Any thoughts?

 

I hope this qualifies as a "Subsequent Observation" (Followed by a question):

I had my gearset installed a few weeks ago. I've put a few hundred miles on it since. My installer was a very qualified Honda Tech who has done 12 diff's previous to mine, but they were all stock gearset's.

Gernby: Am I correct that you set your R&P backlash to 25 thousand's? Mine was set to 20 thousand's and i have the same hi pitched whine as you did. But I also have what I would call a grinding noise under very light throttle in 5th or 6th while just crusing. When it's under load it's as quiet as can be. (I seem to remember another thread with this same complaint but I couldnt find it, hence I posted here) I've drained the fluid and it's clean. No metal filings anywhere.

Any Ideas?? If so please post or PM me so I dont clutter up this thread with my problem.
Thanks.

 

I had my 4.77 installed to factory specs. I have not had an issue with a high-pitched whine nor grinding.

 

YELOSCREAMER, I don't know what would cause the grinding sound. I did set my backlash to 25 thousandths.

 

Although the actual gear calibration was the one part I did not do, it seems to me that there is a LOT being discussed about the ring gear "backlash". This is but ONLY one of many, many critical adjustments that must be used for a correct gear install. The manual seems to dwell more upon tooth contact patterns and this is determined by thrust washer thickness. I do know, however, that finding the correct thrust washer is a matter of trial and error, disassembly and re-assembly of the diff "guts" (in some cases, many, many times) to pop the pinion shaft out and put in a different washer. If the installer is lucky, tooth pattern can be adjusted with ring gear movement only but this is usually not the case. My mechanic said he had to put my diff together 3 times before getting all the measurements to spec. Could it be that some mechanics trivialize the importance of this step in favour of a quick one-time reassembly?
(Or am I missing something here?)

 

[QUOTE]Originally posted by gernby
YELOSCREAMER, I don't know what would cause the grinding sound.