[TnFatBoy]

While my bike was on the Dyno for its tune after being modified, the clutch sliped at peak torque. TNT Performance recommended I get the Harley oil out of the primary chaincase and convert to a 75w90 chaincase product or in the case of 75w80 for Red Line brand. I have read the post and specs on the labels and I will probably go with Red Line. I would really appriciate other opinions from those of you running over 100 ft lbs of Torque.
Jim

[Art_NJr]

Originally Posted by TnFatBoy

While my bike was on the Dyno for its tune after being modified, the clutch sliped at peak torque. TNT Performance recommended I get the Harley oil out of the primary chaincase and convert to a 75w90 chaincase product or in the case of 75w80 for Red Line brand. I have read the post and specs on the labels and I will probably go with Red Line. I would really appriciate other opinions from those of you running over 100 ft lbs of Torque.
Jim

The slippage comes from not having the right additive in the oil & I use nothing but Red Line 75W90 gear lube with the additive for a "limited-slip" differential in the primary in a setup that makes 125 ft/lbs. torque @ the rear wheel on the dyno.

[grandpa tom]

Originally Posted by Art_NJr

The slippage comes from not having the right additive in the oil & I use nothing but Red Line 75W90 gear lube with the additive for a "limited-slip" differential in the primary in a setup that makes 125 ft/lbs. torque @ the rear wheel on the dyno.

TNFATBOY: I agree with Art, from what I ve read when you got over 100#'s tq you may need some better clutch plates in the primary to prevent slipage.

at 16k now Ive used harley primary-transmission dyno oil since 5kand really like it in my 07 heritage. It has all but eliminated the 5th whine and shifts a lot better than the syn3 oil I tried for 4k between 1-5k.

[Art_NJr]

Surprisingly, grandpa tom, we've run a bone stock Sportster clutch in 2 Land-Speed-Record bikes making 167 HP & 125 ft/lbs @ the rear wheel. And the one which went a tick over 180 mph was geared so "tall" it'd go 77 mph in 1st gear. Stock transmission too - just changed the final drive from belt to chain & got different sprockets to change the overall ratio.

And I know 2 independent shop owners (also racers) who will not sell or service aftermarket Barnett clutch products because they've seen nothing but trouble from them. I looked @ the 2 favorite clutches of pro racers - the "Bandit" & the Rivera "Pro Clutch" when putting the LSR projects together, but my friend @ ECS Engineering said you don't really need one (he likes both) & if you'll go get a stock clutchpack, that will do the job you want to do just fine - it's the setup that is the key & you can't be off a thousandth of an inch.

He was right too. The aftermarket clutches are really expensive, I'd poured my "mad money" into the engine & he's got 40 years H-D experience setting clutches up, so I got a new stock clutchpack. Which has not slipped one single time - even launching an LSR bike with a sticky radial tire on a concrete track, over & over again. If you can't kill a stock clutch/tranny in that situation, I don't know how you could on the street.

"Old farts" like me will remember back when if you had a "Posi-I-Traction" limited-slip differential, you had to pour in a little bottle of additive when changing differential gear oil, or the clutches wouldn't work & you wouldn't have "Posi". The additive is already in many gear lubes now, but not all of them - have to read the label. Red Line makes 2 versions of 75W90 - 1 with the additive & the other without - other manufacturers do that too.

With a "wet clutch" setup as in a Harley, you need that additive, or your clutch can slip. Doesn't mean go spend $1400 on a new clutch, just means you've got the wrong fluid in the primary.

[chucktx]

Originally Posted by Art_NJr

Surprisingly, grandpa tom, we've run a bone stock Sportster clutch in 2 Land-Speed-Record bikes making 167 HP & 125 ft/lbs @ the rear wheel. And the one which went a tick over 180 mph was geared so "tall" it'd go 77 mph in 1st gear. Stock transmission too - just changed the final drive from belt to chain & got different sprockets to change the overall ratio.

And I know 2 independent shop owners (also racers) who will not sell or service aftermarket Barnett clutch products because they've seen nothing but trouble from them. I looked @ the 2 favorite clutches of pro racers - the "Bandit" & the Rivera "Pro Clutch" when putting the LSR projects together, but my friend @ ECS Engineering said you don't really need one (he likes both) & if you'll go get a stock clutchpack, that will do the job you want to do just fine - it's the setup that is the key & you can't be off a thousandth of an inch.

He was right too. The aftermarket clutches are really expensive, I'd poured my "mad money" into the engine & he's got 40 years H-D experience setting clutches up, so I got a new stock clutchpack. Which has not slipped one single time - even launching an LSR bike with a sticky radial tire on a concrete track, over & over again. If you can't kill a stock clutch/tranny in that situation, I don't know how you could on the street.

"Old farts" like me will remember back when if you had a "Posi-I-Traction" limited-slip differential, you had to pour in a little bottle of additive when changing differential gear oil, or the clutches wouldn't work & you wouldn't have "Posi". The additive is already in many gear lubes now, but not all of them - have to read the label. Red Line makes 2 versions of 75W90 - 1 with the additive & the other without - other manufacturers do that too.

With a "wet clutch" setup as in a Harley, you need that additive, or your clutch can slip. Doesn't mean go spend $1400 on a new clutch, just means you've got the wrong fluid in the primary.

"The additive is already in many gear lubes now, but not all of them - have to read the label. Red Line makes 2 versions of 75W90 - 1 with the additive & the other without - other manufacturers do that too."

does the additive have a name or number so we can tell which is which????

[Lucifer]

Originally Posted by chucktx

"The additive is already in many gear lubes now, but not all of them - have to read the label. Red Line makes 2 versions of 75W90 - 1 with the additive & the other without - other manufacturers do that too."

does the additive have a name or number so we can tell which is which????

The one to use will have on the back of the bottle "suitable for Limited Slip Differentials" If the Limited Slip Dif is not mentioned it doesn't have the additives in it.

I ran Bel Ray Gear Saver 80-90(has the additives) in my primary and had no problems at all, then on a road trip I had to change starters and used the HD Primary/tranny stuff with the silver label and the clutch slipped every time I hammered it.

[chucktx]

thanks!!

[Art_NJr]

Originally Posted by chucktx

"The additive is already in many gear lubes now, but not all of them - have to read the label. Red Line makes 2 versions of 75W90 - 1 with the additive & the other without - other manufacturers do that too."

does the additive have a name or number so we can tell which is which????

Yes - the one with the "friction modifier" is just called 75W90 & the one without is called 75W90 NS:
Red Line Oil: Gear Lubricants

[chucktx]

i noticed they have a v twin primary oil.....it doesnt state if it has the additive or not.....which would be better????

wish i could go back to the old days.....70wt castor oil every where!!!!!!! lol

much simpler!

[Art_NJr]

Originally Posted by chucktx

i noticed they have a v twin primary oil.....it doesnt state if it has the additive or not.....which would be better????

I haven't tried that Chuck but it does have the additive you need for the clutch in a H-D. I've been so pleased with the 75W90 for the primary & "Shockproof" for the tranny in an application which uses separate fluid from the primary (Sportsters normally share the fluid) that I've just stayed with those.

[Lucifer]

Chuck , I've talked to Bel Ray and they did the same as Red Line in that respect; having a bottle labeled "Primary Oil".The reply was that it's the same oil. The Gear saver Hypoid 80-90 and Primary fluid, they just relabeled the bottle for marketing purposes.
The gear oils I looked at were Castrol and Quaker State(at the local Wally World and CarQuest),didn't see any Valvoline, and the back of bottle said compatible with Limitded Slip Dif's, and was only between $6-$8 Cdn.
70wt Castor Oil would prolly be even a lil cheaper than that too

[chucktx]

the 70wt castor oil is what i have run in my pans and shovels.......
all holes, no muss, no fuss.....bought it by the case!!!

[grandpa tom]

Originally Posted by Art_NJr

Surprisingly, grandpa tom,

"Old farts" like me will remember back when if you had a "Posi-I-Traction" limited-slip differential, you had to pour in a little bottle of additive when changing differential gear oil, or the clutches wouldn't work & you wouldn't have "Posi". The additive is already in many gear lubes now, but not all of them - have to read the label. Red Line makes 2 versions of 75W90 - 1 with the additive & the other without - other manufacturers do that too.

With a "wet clutch" setup as in a Harley, you need that additive, or your clutch can slip. Doesn't mean go spend $1400 on a new clutch, just means you've got the wrong fluid in the primary.

Thanks for the get back, just proves one still cant believe everything in print.
and yes I remember putting that little bottle of extra stuff in the rear diff.
on my early 70's Scout (international) 4WD it was blue and dealer said it was whale oil. matter of fact I still have two of the six, 4oz bottles, because it didnt help the IH oil they had. Switched to something else ??? and it was OK.