I NEED SOME ADVISE ON GEAR LUBE!!!

[Davin]

I'm finishing my brake job and in the morning and I'll need to fill the 'ol pumpkin with gear lube. The install instructions for the brake kit says that I need to add an "Addative Friction Modifier" if I have a Traction-Lok axle. Here are the questions I NEED answered:
1. Stock 94 GT diff..is it Trac-Lok, do I need the addative?
2, The lube I bought is Valvoline Durablend 80/90 SYNTHETIC..(assuming I need the addative) can I use a conventional friction-mod with a synthetic lube or should I go back and get non-synthetic.

PLZ HELP! THANX

 

[GRGT1994]

Yes to both. You need friction modifier. If you run without it, you will get some scary chattering in the rear end as the friction plates operate around corners. I don't think this causes any harm. But it's not recommended, and from what I hear, the noise get very anoying.

Synthetic 80/90 is fine. I have been running it for over a year with the friction modifier additive.

Oh, and ya, the stock 8.8 inch rear end (comes with all 302 motors) does have the friction plates.

 

[HISSIN50]

Yep, all GT's have LSD's. I run the Valvoline blend and ran Ford modifier as well. One school of thinking is that you can certainly try running with no modifier - it is chatters add the modifier. Theoretically, it seems that you could lose some traction if the coefficient of friction is lowered too much (as seen with cars that dont get one-wheel peel till stickier tires are mounted). The only reason I bring up this latter point is that you have a nice lookin combo that probably needs a good bit of traction.

In short, it's easy to add modifier but real real hard to unmodify the pumpkin full of lube.

Good luck.

 

[Grn92LX]

Amsoil 80w90 synthetic gear oil with Amsoil friction modifier user here. No problems at all. I just did my rear about a week ago, all new bearings, seals, 430 gears, 31 spline axles/differential with a girdle.

Any #'s on your combo?

 

[Davin]

cool, thanks for the comments, realy puts me at ease. I guess the fact the my gear arn't stock makes my original assertion that he diff is stock inaccurate, but the fric plates etc are stock...cool, so I think I'll go ahead and give the synth/friction mod a try, worst case is it chatters and I replace it. Doesn't take a lot of opinions when you respect the ones ya got,,thanks fellas..

Grn92LX..no numbers yet..I don't feel I'm getting everything out of her yet..I'm trying to come up with some good timing sheets (TwEECer) before I do..she definitly wants more timing..I'm used to just manually advancing the dist but I'm trying to join Hi-Tech by doing it with the puter

 

[HISSIN50]

so I think I'll go ahead and give the synth/friction mod a try, worst case is it chatters and I replace it. Doesn't take a lot of opinions when you respect the ones ya got,,thanks fellas..

Just for clarity's sake: The modifier makes the clutches slip more. Without any modifier and when using a fluid with a high coefficient of friction (old school conventional gear lube), the clutches bite hard and chatter. This is kinda popular with autocrossers (as can be using a stiffer spring and/or extra packing in the trac lok when rebuilding it).

So with modifier and synthetic, my worry would be that when you launch or fly through a turn while really on-it, one wheel might not put down all the power it otherwise could (not that it might chatter - it better not).

It was worth rehashing that (Brad had already mentioned it) before actually filling it up.

Good luck.

 

[Grn92LX]

Grn92LX..no numbers yet..I don't feel I'm getting everything out of her yet..I'm trying to come up with some good timing sheets (TwEECer) before I do..she definitly wants more timing..I'm used to just manually advancing the dist but I'm trying to join Hi-Tech by doing it with the puter

Shoot for around 34* total. It should make best power around that. I don't know how to use a tweecer but my timing curve in my PMS is 36* total up to 4000 rpm, then from 4000 and up (when the PMS is in standalone) its 34* total.

 

[GRGT1994]

...cool, so I think I'll go ahead and give the synth/friction mod a try, worst case is it chatters and I replace it.

True. But you shouldn't have any problem. BTW, if you haven't already picked up your lube, warning - that stuff is expensive!!

 

[Davin]

Grn92LX

GrGT1994 - I'd like to try what I have (syn/mod) if Hissin would stop scaring me

So with modifier and synthetic, my worry would be that when you launch or fly through a turn while really on-it, one wheel might not put down all the power it otherwise could (not that it might chatter - it better not).

QUOTE]

A little confused on this point...are you saying that your worry is that the syn/mod combo might be TOO slick, and thus depend on only one wheel in the scenarios listed above?

 

[GRGT1994]

Meh, I think you will be fine. That's the same way I'm running it (synthetic lube with friction modifier), and I get solid power at WOT, and through turns - no one wheel peel. Of course, I rebuilt my trac-lok last summer.

If you do start seeing the dreaded one wheel peel, I would suspect your stock trac-lok plates, and you might need a rebuild. But like you said, fill it up and see.

If you are really in the mood to experiment, you could run without friction modifier first. Then if it chatters, drain some fliud and add the modifier. The problem might be draining out some fluid if you dont have a drain plug on your cover (cyphon maybe?). Cheers.

 

[HISSIN50]

Brad summed it up well. I dont mean to scare you. He posted the info correctly, but I see many threads where people think the Modifier helps the clutches bite harder, and we know that's wrong. So I tend to repeat it for enforcement or consensus.

We all do things a little differently - Brad's logic is sound so just do that. If there's slippage, address it at that point.
I dont mind tinkering with stuff (pulling some fluid out with a pump and adding Modifier or leaving the initial fill a little bit low to leave room for a top-off) so I just posted what I would do.

Good luck.