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If youve worked at a shop that installs and repairs differentials id like to know a couple things.
Ive just installed my first limited slip today and i didnt have as wide an assortment of side bearing shims as i needed so i tried to get it as close as possible but sadly theres a harmonic oscillation noise in the 45-55mph range.Notes: Total preload was about 1 foot pound. I dont have a beam type tq wrench in inlbs and no one on the island seems to stock them(spec was 26-33in lbs)
Backlash was .0041-.0051in measured in 4 spots (spec is .0039-.0059)
Contact pattern was showing toe bias on both sides of the teeth
1. Does a shop buy an entire shim set for each vehicle they work on?
2. Each shim costs me 22 dollars. Is there a way to calculate what shims i need to buy before i buy it?
3. Would using brake cleaner to clean the case out contaminate the gear oil when i fill it up later?
4. My contact pattern bias says i should increase backlash but my backlash is within spec. Where should i go from here?
5. Is my car driveable for a while until i can get the shims needed or would i damage my brand new differential?Any help with these questions is greatly appreciated. Thanks
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I would suspect a pinion depth issue is causing you to get a bad gear pattern on this. Most shops have a set of different shims available. Is this a new ring and pinion or reusing the old one? You could use a micrometer to try to figure out which shims you need or to swap a thin one on one side with a thicker one on the other to change the backlash. Remember when all is said and done you will still need to make sure the carrier bearings are properly pre-loaded. The inch pound torque wrench comes in handy there. You can use a piece of string and a very small pull-scale. Thats the old-timer way but you would have to find a spec of pull for that weight.
Brake cleaner won’t contaminate the oil as long as its all been blown out cleanly before you fill it with oil.
I usually feel pinion preload by hand. It should be tightened just past having endplay but still turn smoothly.
I wouldn’t drive it until you get this set up properly or risk damage to the gears.
+1 to Nickwarner. After you do a few diffs you end up with a box of shims you can use. Maybe someone on your island can help you out with extra shims and the torque wrench you’re going to need. Shim packs are available for some, from racing part suppliers for allot less then you are paying.
Thanks for the responses guys. I’m using the original pinion and gears. I didn’t touch the pinion depth because the only thing I was doing was putting in a new lsd so it was just a matter of putting the old ring gear onto the new carrier. Guess the next thing is to shop for a torque wrench.
Being you put a new carrier in does not mean the pinion depth would stay the same. With it being a totally new part all your measurements will be off. I would not drive it or you will end up buying a new gear set also. This is one of those things you need experience to do. Pay someone to set it up, someone who does them all the time and they can save you some money becauese they will have a shim assortment already. Good luck
How would they measure the pinion depth needed for an aftermarket carrier? I called on of the more reputable shops in town and they said they probably wouldn’t be able to do an aftermarket install. I’ve got a shim set and the torque wrench I need now so I’m going to give it one more go.
From what I’m reading in the shop manual for my car, they measure the shim needed for pinion depth with a tool measuring the distance from the pinion location to the centerline of where the carrier would be and adjust with measurements supplied by the ring gear set. It doesnt seem like the carrier changing would make much difference on the pinion depth because the centerline of the carrier doesnt change regardless of what carrier it is, right? I know the side bearing shim sizes will definitely not be the same but can someone educate me as to why the pinion depth would change?
If that pinion was undisturbed, and the bearings were not changed, pinion depth will be the same and correct. The shop you called is right in the tool they have described. As long as your carrier is machined to the proper specs, which I’ve never seen one not be, only the carrier bearing preload and backlash settings are what needs to be adjusted to make this a complete and proper installation. If you were able to find a dial indicator and an inch-pound dial torque wrench you could finish this one yourself. You use the dial indicator to measure the backlash between gears, with the gear pattern test as a final confirmation that all things are good. The inch pound torque wrench is used to determine the proper bearing preload of the assembly, but there may be a different way to go about it. Here in the states we have a company called Randy’s Ring and Pinion that sells a lot of aftermarket diff stuff and you could find their website pretty easily with a google search. I know I’ve seen mention of tech info in the ads for their site in various car magazines. Take a look and see what you find, but you set up an aftermarket carrier the same as a stock one. I think you can take a shot at this one and get a good result. I’m sure you’re tired of your car being in the driveway instead of running around the island.
+ 1 again Nickwarner. With only the carrier being changed, the pinion depth is fine. I did this job last year on an 8.8 in a f-150, reusing the gear set, with no problem.
Its actually easier to set up a semi truck rearend. They use shims between the pinion housing and the differential carrier, instead of a crush sleeve you have a fixed shim for bearing preload. If its too loose you get a thinner spacer. Thicker one if its too tight. You can put that pinion section on a bench too, separate of the carrier ro set it up. Your backlash and preload is changed by threaded pucks with slots for a prybar that couple with the threads cut in the diff housing and the main bearing caps. Tighten them in to get the preload set, then loosen one side and tighten another one notch at a time until the proper backlash. No taking it back apart, don’t need a case spreader, no fuss with getting shims.
I just want to state, while I understand your desire to do this yourself and learn, it seems that you don’t have the requisite tools to do this properly, and you definitely do not want cheap versions of these tools due to their margin of error. I think we all agree on how specific this needs to be done.
It sounds like you are working from a Hayne’s manual, and if that is the case see if you can track down the FSM, as I can personally attest to them having the proper measuring procedures, shim options for your measurements and list of tools you need.
I suspect the reputable shop you called is a repair facility and if that is the case, that explains their reluctance or flat out refusal to do it. This is one of those cases that you find a performance shop with a good reputation to do it.
Otherwise, the advice here is excellent and I do not see anything that was missed, albeit I only have worked with Mitsubishi and Subaru rear differentials, but I cannot imagine it being that much off the wall compared to them.
Good luck, my advice is find a performance shop for this, only because of the accuracy of measurements and tools needed, and that means more money than it usually costs to have it done elsewhere.
I haven’t had much luck with the performance shops in town so I hesitate to go to them. I’m working with snap-on tools that were checked for calibration that I borrowed from a friend that retired from wrenching. And for the manual Im using the Nissan FSM for my car’s year. I’m going to give it one more try and if I can’t get it I’ll take it to a shop
A couple of things come to mind that I did not see mentioned. The first is, did you disconnect the drive shaft at all? If so perhaps it’s not in the correct orientation. It’s usually good practice to mark the location of the U joint before you remove it and install it in the same location to keep things ‘balanced’. If not, vibrations can result. The other thing is the fluid used. With a limited slip a special additive or fluid is used. Lastly, if there is an issue with the diff itself, this could be the cause of your problem despite you doing everything else right. If the tooth contact pattern was good as you say, then I don’t think your installation is at issue as that accounts for pinion depth as well as backlash. It’s kind of the ‘final check’ to make sure everything is good to go and in position as it should be.
[IMG]http://i11.photobucket.com/albums/a156/island03gst/20130215_133405_zpsc6828691.jpg[/IMG]
To anyone thats good at interpreting gear contact patterns.
Need an opinion on my contact pattern before i button it up. Finally got all the specs right (26inlbs total preload, .004in backlash). How does the pattern look to you guys?
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