Oil for bronze cone syncros

[Wolf_Tm250]

Hi,
we have a problem on a customer race car, as its syncros start to have problems really soon after rebuild.
We found that the bronze cone syncros are not able to slow down quick enough the gear, so the syncro get worn and you have to push harder and harder to put the gears in.
And we've been confirmed this theory by the fact that with a 75w90 GL4 seems a lot better than the GL5, probably because GL5 has more anti-friction additive.
So is there any advice on a less-slippery oil I could try in this box?
Thanks

 

[simple_gifts]

vehicle and gearbox mfg would be helpful.

 

[Wolf_Tm250]

Originally Posted By: simple_gifts
vehicle and gearbox mfg would be helpful.


Vehicle is custom, the box is from Toyota

 

[Rand]

what kind of box is it?

what type of gearing does it have?
what does the manufacturer recommend in it?

it is a combo box w/hypoid gearing or something more standard for rwd.


Generic answer since you dont provide enough details to be useful: use a gl-4 designed for a MT

such as redline MTL or MT90

 

[dailydriver]

Maybe it's the AWD 'box out of his Celica??

BTW, Wolf, is that thing rally-prepped (either tarmac, or gravel)?

 

[martinq]

First thing I would try is Motul Gear 300 75w90 (really a 70w90 by the specs). This oil will give a GL5+ level of protection, will not shear and should not affect the synchros. It should also flow better than any other 90 gear oil out there.

 

[simple_gifts]

There are non slip GL-5s

http://www.redlineoil.com/product.aspx?pid=47&pcid=7

 

[Wolf_Tm250]

Thanks for the replies and questions.

I didn't provide other informations because I was just looking for a "generic" reply not too deep in this particular application.
I mean, the point is just to get an oil that will slow down syncro's bronze cones more than a GL4.
But I was probably wrong in this.

Currently we are talking about a RWD car for tarmac, but we have the same kind of syncros even in FWD and AWD Toyota box, so we have the same issues there as well.

We already tried GL5, like the Motul 300, but returned back to a GL4 because is less slippery and syncros work better.

There are no hypoid gears inside, just helical gears with bronze cone syncros... and gears are a bit heavy so the syncro cone doesn't slow down quickly enough.

Thanks

 

[Wolf_Tm250]

Originally Posted By: simple_gifts
There are non slip GL-5s

http://www.redlineoil.com/product.aspx?pid=47&pcid=7




THIS!

THANKS!

 

[Wolf_Tm250]

PS: "NS" aka "non-slip" will help for sure, and we will try it.
But will help even turning to an heavier oil?
Example from recommended 75w-90 to a 75w-140?

Thanks

 

[Rand]

usually no. but you might try it to find out for sure.

It would be hard to find a 75w140 for a transmission though.

Also I'd personally still use a gl-4 over a gl-5 less additives = better shift feel.

without hypoid gearing you dont need to worry about gl-5 vs gl-4 for protection.

GL-5 is required for extreme sliding type loads in units such as Porsche or Subaru that has a combo MT with front DIFF sharing the same oil.

 

[martinq]

Originally Posted By: Wolf_Tm250
We already tried GL5, like the Motul 300, but returned back to a GL4 because is less slippery and syncros work better.


Motul Gear 300 is a GL4 & GL5 unlike just about anything else. Unless you've actually tried it, then you won't know how well it works.

I'd absolutely try Motul Gear 300 unless you're willing to go with a thinner oil.

 

[martinq]

Originally Posted By: simple_gifts
There are non slip GL-5s
http://www.redlineoil.com/product.aspx?pid=47&pcid=7

Not to put anything against Red Line, but the Motul Gear 300 will out-flow this and any other 75w90 out there which should give you faster shifts.

The add-packs for these two are going to be completely different and that could change everything but unless you're going to do a head-to-head comparison I'd go with Motul.

 

[Wolf_Tm250]

Originally Posted By: Rand
usually no. but you might try it to find out for sure.

It would be hard to find a 75w140 for a transmission though.

Also I'd personally still use a gl-4 over a gl-5 less additives = better shift feel.

without hypoid gearing you dont need to worry about gl-5 vs gl-4 for protection.

GL-5 is required for extreme sliding type loads in units such as Porsche or Subaru that has a combo MT with front DIFF sharing the same oil.



I asked because I saw the same Redline Non-Slip is even sold in 75w-140...

 

[Wolf_Tm250]

Originally Posted By: martinq
Originally Posted By: Wolf_Tm250
We already tried GL5, like the Motul 300, but returned back to a GL4 because is less slippery and syncros work better.


Motul Gear 300 is a GL4 & GL5 unlike just about anything else. Unless you've actually tried it, then you won't know how well it works.


We are Motul fan here, and really love their engine's oils we use everywhere!
Anyway the Gear 300 gave us poorer syncro action because too slippery.

 

[Rand]

i buy the redline locally they dont stock the 75w140ns

I guess with the miracle of mail order its not as hard to find.

 

[martinq]

Originally Posted By: Wolf_Tm250
Anyway the Gear 300 gave us poorer syncro action because too slippery.

OK, well in that case try Red Line MT-90.
http://www.redlineoil.com/product.aspx?pid=46&pcid=7

 

[default]

I've found thicker oil sometimes helps, a bottle of STP mixed with PZ synchromesh seemed to help out the shifting in the worn out(factory fill full of metal when I got it) trans in my Sunfire. Lucas also claims their "transmission fix" will help synchros, I'm inclined to believe this, as it's meant to make worn clutches grab.

 

[Wolf_Tm250]

Thanks all for the help!
I really think, first of all, I'll try the NS Red Line oils and see what happens...
Regards!

 

[martinq]

Originally Posted By: Wolf_Tm250
I really think, first of all, I'll try the NS Red Line oils and see what happens...

Please let us know. I don't think the 75w90 will perform as well as the MT-90 but it could be close.