mountaingoatgruff Posted June 21, 2008 Share Posted June 21, 2008 i decided to replace the oil in my rear diff and thought maybe i'd try cleaning it out a bit in the process. so i drained the oil and refilled it with a few ounces of seafoam and then oil to the level, then i drove it on the freeway for a good 15 minutes. got it home, drained and refilled with fresh oil. seems like it helped, its noticably quieter (psychosomatic?) and certainly cleaner. i'm sure this is nothing new, but any opinions on this personal experiment? Quote Link to comment Share on other sites More sharing options...
3eyedwagon Posted June 21, 2008 Share Posted June 21, 2008 I'm not one to argue maintenance, especially the replacement of vital fluids. The change of rear diff fluid is OFTEN overlooked in favor of easier, and more commonly advertised forms of maintenance. I personally have never "flushed" a rear end though. I've had many apart, and have never really seen any evidence that a flushing may have prolonged their lives. I could see it making a difference in the case of a LSD, or some other form of clutch, or hydraulic actuated traction device, but not much in a standard diff. However, I'm not sure of what flushes could hurt, or help some kinds of clutch bands.... All you really did was lower the viscosity of the contents of the rear diff, making them drain quicker, and easier. You may have gotten a little grime off the inside of the rear casing, but that will be back in 10k miles. I don't doubt a bit that it is quieter, even though doing your own work on things such as this often makes one notice the results even more. I personally would attribute the noise reduction more to new fluid, and not so much the flush job. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 21, 2008 Share Posted June 21, 2008 It is neccesary, for obvious reasons, to clean the insides of a diff being prepared for welding very well. I've welded three diffs, and each time I've cleaned the insides out with an evaporating degreaser and dried them very well so as not to start fires. I can tell you that for a stock height vehicle the R&P on the R160's is quite strong - so strong that I wouldn't worry about it unless it were making some serious noises. I can't see a short drive with seafoam hurting them much - especially since they almost never fail and most probably have 20 year old fluid in them. I recently changed the diff oil in my 83 hatch - it came out pretty dark so it was probably original. I just did it on general principle as it's likely been 25 years and 225k miles. I'll probably never change it again unless I weld it up - which I may do as I have an idea for a slightly different welding technique that I want to try. GD Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 21, 2008 Share Posted June 21, 2008 can't hurt. did the fluid come out dark when draining the second time? i like the idea. Quote Link to comment Share on other sites More sharing options...
mountaingoatgruff Posted June 21, 2008 Author Share Posted June 21, 2008 my hatch has 177k (which ain't too much by standards around here) and the gear oil came out reeeeeal dark, certainly original oil. after driving with the seafoam in there the oil came out just as dark and it wasn't noticeably thinned though the viscosity certainly was lowered. also, the first time i drained it very little chunky gunk came out with the last bit of oil. after seafoaming there was a steady stream of chunky gunk to the last drop of oil. i considered basically "rinsing" it and replacing the oil again in a few hundred miles but that's probably overkill, especially considering how much this oil costs. i set my timing a few days earlier and noticed my car had much more oompf and when i did my diff i also put my tires at 38psi in the front and 35psi in the rear. i had been pretty dissapointed with my mileage (it was in the low 20's somewhere) but it looks like it's gone up drasticly on account of those few things (i know its mostly the timing being corrected:rolleyes:). looks to be in the 30's now but i'll need some more time to verify. Quote Link to comment Share on other sites More sharing options...
2K4 STI Posted June 22, 2008 Share Posted June 22, 2008 What ratio of seafoam to Diff oil did you guys use? And is it safe for the LSD rear diff on my RX? Quote Link to comment Share on other sites More sharing options...
mountaingoatgruff Posted June 22, 2008 Author Share Posted June 22, 2008 i did it with about 2 - 3 ounces seafoam and a balance of proper oil to the proper level. i can't say whether its safe for lsd's or not. i imagine that might be kind of a gamble but i'm not well educated when it comes to lsd's so i can't speak with authority on the matter. i'm sure somebody here can tell you, though. Quote Link to comment Share on other sites More sharing options...
joostvdw Posted June 22, 2008 Share Posted June 22, 2008 What about draining the old diff fluid, mixing it 50/50 with ATF and putting it back for another 100miles? I ask this because the stores here don't carry seafoam and I think ATF lubricates better then seafoam as well as cleaning the inside of the diff. Also, since ATF is more of an oil then seafoam, it may be better when put into an LSD. Quote Link to comment Share on other sites More sharing options...
carfreak85 Posted June 25, 2008 Share Posted June 25, 2008 *Sits on fence waiting for more info about flushing LSDs.* Quote Link to comment Share on other sites More sharing options...
2K4 STI Posted June 26, 2008 Share Posted June 26, 2008 *Sits on fence waiting for more info about flushing LSDs.* +1 Quote Link to comment Share on other sites More sharing options...
Greenley Posted June 26, 2008 Share Posted June 26, 2008 +1 +2 :-p Quote Link to comment Share on other sites More sharing options...
mountaingoatgruff Posted June 26, 2008 Author Share Posted June 26, 2008 i really wish i had the answer. all i can say it that when my buddies cleaned their mopar 8 3/4" posi's they'd pop the axles out and pull the whole carrier (bajo axle) then dunk it in some kinda home-made soup of cleaners. i'll try to get ahold of one of them and see if they'll share the recipie but i think if you're that interested in safely flushing an lsd you should just change the fluid a few times in 100-200 mile intervals. i'm sure that's more than would be necessary in itself, and costly enough too! Quote Link to comment Share on other sites More sharing options...
bobaru Posted June 26, 2008 Share Posted June 26, 2008 *Sits on fence waiting for more info about flushing LSDs.* NEVER EVER flush a limited slip diff the clutch disks in the LSD,s NEEDS a limited slip additive If you were to put seafoam, marvel mistery oil, ATF,....ETC ETC ETC it will dieloute the additive and FRY the clutch packhttp://en.wikipedia.org/wiki/Limited_slip_differential Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 26, 2008 Share Posted June 26, 2008 makes sense. unless there's a compelling reason to play with it, it seems best left alone. change to synthetic and you should be good to go. they fail so rarely i can't think of a good reason to try anything out of the ordinary. Quote Link to comment Share on other sites More sharing options...
bobaru Posted June 26, 2008 Share Posted June 26, 2008 my link failed to wiki just goggle limited slip differential lots of info Quote Link to comment Share on other sites More sharing options...
mountaingoatgruff Posted June 26, 2008 Author Share Posted June 26, 2008 NEVER EVER flush a limited slip diff the clutch disks in the LSD,s NEEDS a limited slip additive If you were to put seafoam, marvel mistery oil, ATF,....ETC ETC ETC it will dieloute the additive and FRY the clutch packhttp://en.wikipedia.org/wiki/Limited_slip_differential that's why i said "...if you're that interested in safely flushing an lsd you should just change the fluid a few times in 100-200 mile intervals. i'm sure that's more than would be necessary in itself..." my mopar buddy is in montana right now so i can't ask him what he used to clean his posi's with, but that's 60's and 70's mopar 8 3/4's and danas. Quote Link to comment Share on other sites More sharing options...
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