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Swapping rear discs for the drums and aburn lsd for open carrier. Stock 3.08 gears. Got everything in and buttoned up tonight. After many cycles of setting the backlash on the carrier and reading patterns, it is not right. I didn't get and pictures of the pattern so bare with me on that aspect. Also, I didn't touch the pinion. Just the carrier and ring gear.
THE PROBLEM- rear is dead silent when accelerating and decelerating. BUT when coasting (either in gear or not) and turning RIGHT, the rear wines. Accelerating when turning right it is silent again. Turning left it is silent both accelerating and decelerating.
Going into this I knew there would be trial and error but I am lost on why it only wines when coasting right and no other times.......
What did you set the backlash at? And also without a picture of the pattern, it's hard to tell where your at. If you knew it wasn't right, you should have waited until you had help from here or someone else before driving it.
If it changes from turning, then something is not mounted rigidly enough. Probably not enough shims to keep the carrier from shifting left to right. Try getting more shims in there. You can't have enough pre-load. Some people even use special tools to spread the case so they can get more carrier bearing pre-load.
Did you measure the backlash before you took it apart?
Used gears make different patterns. That usually requires a more experienced eye.
If it changes from turning, then something is not mounted rigidly enough. Probably not enough shims to keep the carrier from shifting left to right. Try getting more shims in there. You can't have enough pre-load. Some people even use special tools to spread the case so they can get more carrier bearing pre-load.
Did you measure the backlash before you took it apart?
Used gears make different patterns. That usually requires a more experienced eye.
GD
That is a GREAT answer - and most likely correct. It makes sense.
To clarify for those who I mislead when explaining. (Long day and a late night my apologies)
Red Rock- After looking at patterns and setting lash I was under the impression it was correct. It wasn't until After driving and hearing noises that I thought something was obviously wrong, hence why I came here.
NoEmissions84TA- DEFINITLY have it backwards. Disc and Lsd are going IN. Sorry if I made that sound the other way around.
Now back to the issue, Before disassembly it was sitting at about .08 lash. I tried to get it as close I could to that point when reinstalling. Some spots are a little tighter and some a little looser around the gear. Does this need to be increased or decreased?
As pertaining to carrier pre-load, GeneralDisorder, I had thought that I was doing an OK job off getting it tight with the shims. But I obviously might very well be wrong. Should I try to Add shims equally on both sides of the carrier? I might be able to get two more in but it will take some effort.
Thank you all for the quick responses, I was honestly a bit shocked as I read them all This am. It will be getting torn apart tomorrow after noon as I am helping A friend run his outlaw late model at the track tonight. At that point I can get some pictures up of the pattern and where the lash ended up at after all of this.
How much variance in backlash do you have as you turn the gear?
Did you clean and deburr the ring gear and carrier mating surfaces to insure the ring gear is pulled down tight and flush?
Shimming can be tough - you typically want to sandwich the small shims between two thicker ones if you can so you can drive them in. Have to tap them in with a hammer usually. You want it as tight as possible really. At least I've never seen one fail because someone was able to get too much carrier preload.
Another thought - was this a new or used Auburn style carrier? Those cone type LSD's are garbage in this man's Army.... They make all kinds of noises if they don't have real specific additive in the lube too.
The Torsen carriers availible now are much more street friendly. They don't wear out, they have manners like an open diff, and when you punch it they lock right up.
GD
Last edited by GeneralDisorder; 07-07-2017 at 10:47 AM.
Not enoug bearing preload was exactly my thought when I read the first post. You have to get it tight enough that you can't pull it out by hand.
The Auburn might be making the noise. I usually have to use 2 bottles of the GM limited slip oil additive with the Auburn. A new Auburn is not much good and a used Auburn is 10 times worse. I understand that sometimes you have to use what you have, but don't ever buy a Auburn if you have another option.
Have it opened up again. Back lash is from about .008 - .010 around the gear.
Yes the carrier and ring gear were surfaced before being assemblemed.
I will attach pictures of the patterns. Very sorry in advance and mad at my self for it, but I have a couple of different shops that I can work in and I forgot to grab marking compound. Axle grease was the next
best. (Better than nothing hopefully?)
This is a new aburn unit. I did want a Torsen style, but my problem was that I wanted to keep the 3.08's because the car sees a lot of high way. I was having trouble finding a series 2 carrier that was preloaded to prevent it acting like an open carrier during a wheel in the air scenario around a corner. (Which is why I wanted a limited carrier in the first place) if I missed one by all means show me. We learn from mistakes and this one will wear out eventually!
Right now I am going to keep the lash were it is. I think this SHOULD be alright for used gears, and add shims equally on both sides to add in some pre-load to the bearings as you guys seem to agree that may be the root problem.
Should I try to Add shims equally on both sides of the carrier?
Yes, once you have the backlash like you want it.
I can't tell much if anything about your gear contact patterns from those pics. In my experience however, I've always found a .035" shim on the pinion, from the factory; EVERY SINGLE one I've ever taken apart. So rather than outsmart myself about "pattern" I just always put a .035" back in. Haven't ever had a problem yet.
To set the backlash, I do the same thing as everybody else; adjust the shim packs on either side to get what I want. I prefer to set it toward the high end of the spec, since gears GROW as they get hot, which makes the backlash go away... the consequences of having slightly more backlash than whatever might be "ideal", are FAR less serious than the consequences of 2 moving metal parts being forced to occupy the same volume at the same time. I use 2 large C-clamps on the carrier bearing races to compress them, and add equal shims on both sides after setting the backlash, to the point that I can just barely get the carrier w/ bearings to go in with the 2 C-clamps compressing the bearings, and the shims sitting in the case. Usually that's at least .005" more per side than when I can get the carrier to go in by hand.
Finally have it back together, I was able to add .015 of shim on either side of the carrier. It tightened the lash up by maybe .001 but no big difference.
It fixed the turning problem. It is slightly louder on deceleration, mostly only if you are down shifting from 50 down to about 30, but nothing loud enough to be concerning. On Michigan roads you have to be on a new stretch of road and be listening for it to hear anything.
Apart from that it runs perfect! We will see if I can live with the aburn now 👍🏻
Thanks everyone for the advice!!!!
(There isn't much TGO can't figure out, except for agreeing on if a 305 is junk or an underdog motor..... but that's another can of worms haha)
07-06-2017, 10:00 PM
I use 2 large C-clamps on the carrier bearing races to compress them, and add equal shims on both sides after setting the backlash, to the point that I can just barely get the carrier w/ bearings to go in with the 2 C-clamps compressing the bearings, and the shims sitting in the case. Usually that's at least .005" more per side than when I can get the carrier to go in by hand.