Friction modifiers - yay or nay?

sparky · 1 April 2011

For a gearbox in excellent condition, with the idea of making changes even slicker on track, and possible to improve reliability .... does anyone use / recommend using friction modifiers (like from redline or royal purple) either added to or completely replacing the standard gearbox oil ?

stuntman · 2 April 2011

Probably not a good idea, especially since the trans/diff fluid are combined and friction modifiers will affect the function of the clutch discs in the diff (especially the stock LSD -which needs all the help it can get).

Use OEM Honda, or Redline MT90/MTL/whatever.

Mac Attack · 2 April 2011

Like Billy said, the stock LSD sees the MTF.

But, you have a 20 YO LSD. Unless the synchros have been replaced, or you've rebuilt the LSD, it's getting old. The LSD clutch packs are probably worn, the spring has lost some preload due to age, and your sychros may be a little worn.

Personally, I've tried the old Honda MTF, the new Honda MTF, the GM friction modified blend, and lately, the Amsoil MTF (that says it's not for wet LSD's).

My transmission was rebuilt with new synchros (when I did a preventative snap ring fix about 6 years/65k miles ago), and I could tell an improvement in shifting smoothness when going from the new Honda MTF to the GM Friction modified blend. Just 8 months ago, I swapped out the GM blend for the Amsoil MTF. The Amsoil MTF has the same synchro smoothness as the GM blend, but I can feel the LSD being more aggressive than before.

It's not locking up the inside wheel or even chattering on slow tight turns, (like some American performance cars do with LSD's), but I imagine it feels like it was some 20years and 125k miles ago!

I'm prepared to accept any potential consequences of accelerated LSD clutch pack wear the Amsoil may cause. My $0.02.

Dave

stuntman · 2 April 2011

Mac Attack said:
Like Billy said, the stock LSD sees the MTF.

But, you have a 20 YO LSD. Unless the synchros have been replaced, or you've rebuilt the LSD, it's getting old. The LSD clutch packs are probably worn, the spring has lost some preload due to age, and your sychros may be a little worn.

Personally, I've tried the old Honda MTF, the new Honda MTF, the GM friction modified blend, and lately, the Amsoil MTF (that says it's not for wet LSD's).

My transmission was rebuilt with new synchros (when I did a preventative snap ring fix about 6 years/65k miles ago), and I could tell an improvement in shifting smoothness when going from the new Honda MTF to the GM Friction modified blend. Just 8 months ago, I swapped out the GM blend for the Amsoil MTF. The Amsoil MTF has the same synchro smoothness as the GM blend, but I can feel the LSD being more aggressive than before.

It's not locking up the inside wheel or even chattering on slow tight turns, (like some American performance cars do with LSD's), but I imagine it feels like it was some 20years and 125k miles ago!

I'm prepared to accept any potential consequences of accelerated LSD clutch pack wear the Amsoil may cause. My $0.02.

Dave

Friction modifiers do not increase the agressiveness of the LSDs clutch plates but rather cause them to slip more. Chattering of a rear end is due to a differential not differentiating the wheelspeeds between the two tires (because its locking them at the same speed) and the inside tire binding up then slipping and exaggerating bushing deflection causes the chatter. Adding friction modifiers to the NSX LSD would hurt the locking ability, this is in the opposite direction that would cause chatter (too much lock). The stock LSD does not have ramp angles in it and relies entirely on the preload of the clutch packs -not the most performance oriented design.

Since your LSD is so old its probably worn out, adding Friction modifiers would just further reduce its lockup ability and exaggerate inside wheel spin.

0.02

sparky · 2 April 2011

My question was for a new 'box without any wear. Yes my transmission is old, but I've purchased a new 'box and will fit it soon, so my "excellent condition" statement is actually an understatement for that 'box.

So it seems you're recommending I just go with standard Honda recommended MTF? Referring to workshop manual, for my warm climate (very rarely below freezing) MTF can be same oil as in the engine = Honda FEO 10W-30.

(As an aside: my old transmission is not in excellent condition, fast 2nd to 3rd changes are guaranteed to crunch badly. NSX_SA had similar problem and added "Royal Purple" to some good effect. It tried the same but no difference. Presumably my synchros are in very poor condition)

stuntman · 2 April 2011

I track my car heavily on hot days with Honda MTF. I would just stick with that since it was designed for the gearbox.

Mac Attack · 3 April 2011

stuntman said:
Friction modifiers do not increase the agressiveness of the LSDs clutch plates but rather cause them to slip more. Chattering of a rear end is due to a differential not differentiating the wheelspeeds between the two tires (because its locking them at the same speed) and the inside tire binding up then slipping and exaggerating bushing deflection causes the chatter. Adding friction modifiers to the NSX LSD would hurt the locking ability, this is in the opposite direction that would cause chatter (too much lock). The stock LSD does not have ramp angles in it and relies entirely on the preload of the clutch packs -not the most performance oriented design.

Since your LSD is so old its probably worn out, adding Friction modifiers would just further reduce its lockup ability and exaggerate inside wheel spin.

0.02

I have no idea what Amsoil uses - It just says "Not for use with LSD's."

When I put it in my LSD, it is more aggressive, i.e. the clutch packs are slipping less. I like it more and imagine it's how it felt a LONG, LONG time ago! I never said the friction modifiers made it more aggressive

Since there doesn't seem to be a comprehensive side-to-side comparison of MTF's that I know of, it's pretty much just try it and see what happens!

Dave

stuntman · 3 April 2011

Mac Attack said:
I have no idea what Amsoil uses - It just says "Not for use with LSD's."

When I put it in my LSD, it is more aggressive, i.e. the clutch packs are slipping less. I like it more and imagine it's how it felt a LONG, LONG time ago! I never said the friction modifiers made it more aggressive

Since there doesn't seem to be a comprehensive side-to-side comparison of MTF's that I know of, it's pretty much just try it and see what happens!

Dave

How do you know the clutch packs are slipping less? What is it doing/feel like?

Friction modifiers should make the clutches slip MORE.

This is one of the rare articles that actually do a good job explaining differentials and how they behave, and what friction modifiers do:

http://www.syntheticoilnlubes.com/amsoil_friction_modifier.html

Billy

sparky · 3 April 2011

Interesting discussion ....

Whilst that AMSOIL info-advert talks about reducing chatter (using their product), it fails to mention the downside, which I assume would be more slip in the LSD, so transferring less torque to the inside wheel. i.e. it's LSD effect would be reduced. But it seems Mac_Attack's experience is the opposite ?

Anyway as suggested, playing with "friction" in a situation like this is a delicate balancing act involving many variables ... "suck it and see" is probably the only way to find the best optimum for a specific car/driving situation.

stuntman · 3 April 2011

sparky said:
Interesting discussion ....

Whilst that AMSOIL info-advert talks about reducing chatter (using their product), it fails to mention the downside, which I assume would be more slip in the LSD, so transferring less torque to the inside wheel. i.e. it's LSD effect would be reduced. But it seems Mac_Attack's experience is the opposite ?

Anyway as suggested, playing with "friction" in a situation like this is a delicate balancing act involving many variables ... "suck it and see" is probably the only way to find the best optimum for a specific car/driving situation.

Friction modifier reduces chatter by causing the clutch plates to slip more -thus reducing the effectiveness of the lsd. This exaggerates inside wheelspin by preventing the clutch plates from staying locked together
. Thus MORE torque is transferred to the inside wheel because the clutch plates slip more (due to the reduced friction from the friction modifying additive) and less is transfered to the outside loaded wheel because of the slippage. I'm a bit confused with Mac_Attacks experiences, maybe I'm not understanding it correctly. A lot is lost in translatiion through text.

Billy

Mac Attack · 4 April 2011

After adding the Amsoil MTF, my clutch packs slip less, i.e. I get increased chatter in slow tight turns. The LSD is now (slightly) more aggressive.

Not a HUGE difference, but subtle enough that it's how I imagine my old car would have been off the showroom floor, and not how it currently sits with 125k miles on the clutch packs and a spring that's relaxed slightly.

I've personally tried the old Honda, new Honda, and GM MTF's, and they didn't feel like this. I like it and will see how it holds up.

Dave

stuntman · 4 April 2011

Mac Attack said:
After adding the Amsoil MTF, my clutch packs slip less, i.e. I get increased chatter in slow tight turns. The LSD is now (slightly) more aggressive.

Not a HUGE difference, but subtle enough that it's how I imagine my old car would have been off the showroom floor, and not how it currently sits with 125k miles on the clutch packs and a spring that's relaxed slightly.

I've personally tried the old Honda, new Honda, and GM MTF's, and they didn't feel like this. I like it and will see how it holds up.

Dave

Interesting. I don't think a new or low mileage OEM NSX diff chatters, or that Honda would find that acceptable. The low mileage NA1 and brand new 04 I drove didn't chatter from what I recall. Sorry I'm having trouble explaining your experiences.

Billy

syndicate · 4 April 2011

Aww man! I was seriously considering putting Amsoil in my tranny because I have notchy shifting when running through the gears, but if this might defeat the LSD function...poop! I see MacAttack has results that are unexpected if what Billy says is true. What to do? Im with the Aussie on this one and have no idea which way is best.

Mac Attack · 4 April 2011

syndicate said:
Aww man! I was seriously considering putting Amsoil in my tranny because I have notchy shifting when running through the gears, but if this might defeat the LSD function...poop! I see MacAttack has results that are unexpected if what Billy says is true. What to do? Im with the Aussie on this one and have no idea which way is best.

Is my technical writing so messed up that no one can understand me

:biggrin: You people must be related to my wife....

The Amsoil does not defeat the LSD function.

If you're having problems with the synchros, I would recommend the new Honda MTF stuff if you haven't tried it yet. If that's what you're using now, I would put in the GM Friction Modified concoction discussed in another thread on Prime.

stuntman said:
Interesting. I don't think a new or low mileage OEM NSX diff chatters, or that Honda would find that acceptable. The low mileage NA1 and brand new 04 I drove didn't chatter from what I recall. Sorry I'm having trouble explaining your experiences.

My original post was more correct - there is no real chatter, but I can tell the diff is a lot stiffer now.

Even more off topic now, but didn't Honda change LSD designs for the NA2?

Dave

robbiedawg · 4 April 2011

in 95,the lsd changed
http://www.nsxprime.com/wiki/Changes_by_Year

stuntman · 4 April 2011

Mac Attack said:
Is my technical writing so messed up that no one can understand me :biggrin: You people must be related to my wife....

The Amsoil does not defeat the LSD function.

If you're having problems with the synchros, I would recommend the new Honda MTF stuff if you haven't tried it yet. If that's what you're using now, I would put in the GM Friction Modified concoction discussed in another thread on Prime.

My original post was more correct - there is no real chatter, but I can tell the diff is a lot stiffer now.

Even more off topic now, but didn't Honda change LSD designs for the NA2?

Dave

I'm really struggling to follow. Text is a terrible means of communication. At first you said the fluid made it more agressive and chatter, then it didn't, then did, and now dosnt again. I'm not sure what characteristics that you're feeling that make it feel stiffer despite the chatter (or lack there of).

The OEM diff shouldn't chatter and the preload is the most lock/resistance the diff will see, there is no ramps to progressively tighten and squeeze the clutch discs like an aftermarket salisbury unit.

The design of the OEM unit did change to have more holding capacity but it still shouldn't chatter. Also friction modifier increases slipping for better engagement of synchros, but this increases slipping and hurts the performance of the already weak OEM diff, let alone a worn out one.

0.02

Mac Attack · 4 April 2011

stuntman said:
I'm really struggling to follow. Text is a terrible means of communication. At first you said the fluid made it more agressive and chatter, then it didn't, then did, and now dosnt again. I'm not sure what characteristics that you're feeling that make it feel stiffer despite the chatter (or lack there of).

As you said, the OEM is pretty weak.

And, only driving it on the street isn't the best measure of how effective it is.

I can only tell a change due to low speed parking lot turns, where there is no real "chatter" (since it seems the OEM diff is impossible to really bind up), but there is certainly an increased scrubbing of the inside tire.

I can't really tell any increase in understeering (since I'm not doing any aggressive turning on the street), but there is less inside tire slippage when accelerating aggressively on a corner exit.

That's why I like it. I encourage others to try it if they're looking for something different. I previously posted the same information here:
http://www.nsxprime.com/forums/showpost.php?p=1392103&postcount=27

My $0.02.

Dave

stuntman · 4 April 2011

Mac Attack said:
As you said, the OEM is pretty weak.

And, only driving it on the street isn't the best measure of how effective it is.

I can only tell a change due to low speed parking lot turns, where there is no real "chatter" (since it seems the OEM diff is impossible to really bind up), but there is certainly an increased scrubbing of the inside tire.

I can't really tell any increase in understeering (since I'm not doing any aggressive turning on the street), but there is less inside tire slippage when accelerating aggressively on a corner exit.

That's why I like it. I encourage others to try it if they're looking for something different. I previously posted the same information here:
http://www.nsxprime.com/forums/showpost.php?p=1392103&postcount=27

My $0.02.

Dave

what is "scrub" that you are feeling at low speed?

Honcho · 4 April 2011

FWIW, I increased the pre-load on my 91 diff using the NSX-R shim. We tested the break-away torque on the bench before and after. Before = 54 lb/ft After = 115 lb/ft

My diff had 83,XXX miles at the time and, as the above numbers show, tested near the brand-new spec (my synchros did as well). On visual inspection, thre was only minimal wear on the friction plates. This differential exclusively used OEM Honda fluid, which was changed at the recommended intervals. I think this is a good example of why it is important to keep up on your fluid changes.

As for slow-speed driving/parking, I feel no difference between the OEM and NSX-R preloads.

ralph cerbone · 5 April 2011

stuntman said:
I track my car heavily on hot days with Honda MTF. I would just stick with that since it was designed for the gearbox.

listen to what hes saying ,you can't have it both ways , set a diff tight for the track it will chatter around town , i've played this game for along time figure out what you want and adjust accordingly , somethings never change!!!:wink:

stuntman · 5 April 2011

ralph cerbone said:
listen to what hes saying ,you can't have it both ways , set a diff tight for the track it will chatter around town , i've played this game for along time figure out what you want and adjust accordingly , somethings never change!!!:wink:

We tried greatly increasing the preload far beyond the NSX-R preload on the FXMD NSX and while better, it just wasn't up to the task of high HP track use. Even with all this preload, it did not chatter at low speeds. A more agressive race unit like OS Giken can be tuned not to chatter (like mine) so you can have the best of both worlds. It just takes a lot of R&D. FWIW my stock NA1 LSD was also around 50lbs of preload which basically dosnt do anything.

0.02

PhiAlpha44 · 5 April 2011

I've heard wonderful things about Motorkote.

www.motorkote.com

ralph cerbone · 5 April 2011

stuntman said:
We tried greatly increasing the preload far beyond the NSX-R preload on the FXMD NSX and while better, it just wasn't up to the task of high HP track use. Even with all this preload, it did not chatter at low speeds. A more agressive race unit like OS Giken can be tuned not to chatter (like mine) so you can have the best of both worlds. It just takes a lot of R&D. FWIW my stock NA1 LSD was also around 50lbs of preload which basically dosnt do anything.

0.02

most of my diff work was with FR cars,because they didnt have much weight in the rear it didnt take that more preload on the clutch packs to make them chatter , most guys didnt care ,they just wanted to see two black lines on the pavement

BATMANs · 12 July 2016

Was wondering if there has been any updates or new products on the market that anyone would like to share.

These are the 2 friction modifiers that I have had good luck with other vehicles.

Was wondering if anyone had any experiences.

https://www.amsoil.com/shop/by-product/gear-lube/slip-lock-gear-oil-additive/

http://www.torcousa.com/torco_product/limited.html

Friction modifiers - yay or nay?

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