If you go straight to the rear end manufacturer - you know - the people that actually build them - test them - race them.... they'll tell you the correct info based on having manufactured millions of 'em.
There are a couple of different scenarios at play here Greg, each with different circumstances, needs and results. In regards to strictly gears...I agree that new ring and pinion gears need dino oil used with them until they are broken in. Once broken in though, I see no reason why synthetic gear oil can't be used on ring and pinion gears. My ring and pinion gears were broken in on dino oil but have had synthetic run on them for the last couple of years...and they have seen a ton of abuse and still look perfect.
Now, differentials...are another circumstance. Gear type lockers...I'm not sure what's best to use with them and when as I've never owned one.
Clutch type posi's though...from one horses mouth that builds and races a lot of these...dino or synthetic gear oil is fine either way...as long as a friction modifier is used to help the clutches slip. I can't see why being "too slippery" would be a deterrent at least when breaking in a new clutch type posi, especially after dealing with this the last few days...
Now I'm not an expert, but I have just listened to a LOT of them...with lots of different thoughts on this. I just wanted to post this to show that not all diffs are apples to apples, different scenarios are at play here.
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Lance
1985 Monte Carlo SS Street Car
Don't think for a second that that hasn't crossed my mind...
It's gotten much better since I put the friction modifier in it. I'm going to try to get it to 200 miles before my race on Sunday and hopefully it'll be fully broke in by then.
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Lance
1985 Monte Carlo SS Street Car
Just go to the manufacturer website. I don't need to argue it further. Some of their rear ends can use synthetics and some can't. The key is to know which can and can't. I'm just using the data off eatons website.
If you go straight to the rear end manufacturer - you know - the people that actually build them - test them - race them.... they'll tell you the correct info based on having manufactured millions of 'em.
NO SYNTHETIC GEAR LUBE.
Okay - that's all I'm going to say about that.
I was told this multiple times but after smoking several gears in succession, 1 set didn't even make it through 1 trackday, these were REM finished gears and the 3rd member was dynoed. I changed to Mobil 1 LSD on recommendation of C&R Racing and have had zero issues with the Tru-trac or gears since.
Lance, if you can't get this worked out... I have a freshly rebuilt 31 spline wavetrac if you need it. You pay for the shipping and install it, if it works out for you pay me whatever you feel it worth, if it doesn't work in your car use it for a paper weight or throw it in the dumpster... I have no use for it since it doesn't work with a floater unless you capture the axles somehow.
That is a very generous offer Tim, I really appreciate that. I have never heard of the Wavetrac before, so I did a little bit of reading up on it and it sounds interesting. If things turn South with this current diff, I just may take you up on that.
I think things are getting better here the more I drive it. I've talked with a few Ford friends and several of them have told me it can take up to 200 miles or so before the chattering stops, especially if the tracloc is set up pretty tight as this one is supposed to be. I've got about 85 miles or so on it now. I'm supposed to bed the brake pads in at 150 miles...so sometime on Saturday I'm going to go for a pretty spirited drive to shake things completely out.
I sure didn't mean to start a synthetic vs dino oil argument here as that seems to be hashed out already ad nauseum. It is interesting to me though that there is still that much disagreement over the issue even after all of these years. Seems to me that once one finally hits on something that works for them, they believe in it and use it there after and there is nothing wrong with that. Hopefully the use of friction modifier in clutch type diffs is a bit clearer now though.
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Lance
1985 Monte Carlo SS Street Car
I was told this multiple times but after smoking several gears in succession, 1 set didn't even make it through 1 trackday, these were REM finished gears and the 3rd member was dynoed. I changed to Mobil 1 LSD on recommendation of C&R Racing and have had zero issues with the Tru-trac or gears since.
I'm on the road --- long trip in the '33 -- SF to LA - up the coast - and now a 725 mile drive today.
I "think" the True Trac CAN run Synthetic (I just never can remember) --- but some of these diffs can't. I never remember which ones can and can't ACCORDING to EATON (the Manufacturer). I don't think it's a ring and pinion issue -- but rather the "post mechanism" that is affected.
My point in all of this is to make sure you know what you're running and check the manufacturers specs.
I'm on the road --- long trip in the '33 -- SF to LA - up the coast - and now a 725 mile drive today.
I "think" the True Trac CAN run Synthetic (I just never can remember) --- but some of these diffs can't. I never remember which ones can and can't ACCORDING to EATON (the Manufacturer). I don't think it's a ring and pinion issue -- but rather the "post mechanism" that is affected.
My point in all of this is to make sure you know what you're running and check the manufacturers specs.
the Eaton clutch posi's run on mineral based and slip additive. True tracs and most gear type LS like sythetic and no additives. The GM stuff works great and smells like grapes.
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
I just wanted to post this to show that not all diffs are apples to apples, different scenarios are at play here.
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