Clutch slipping

[JW113]

HTT-ers,

So I've been doing a lot of fine tuning on my '78. Now that I've got the carb and exhaust dialed in better, am finding that the clutch is slipping in 4th gear at full throttle. I had replaced this POS "red" spring with a set of dual "stock-ish" springs from Eastern MC parts. Although, they are not stock OEM, so who knows if they are up to the task or not.

I believe I have the disk pack height set correctly. And the clutch release adjustment seems good, about 1/8th inch free play on the cable.

Any suggestions? I found a set of OEM inner/outer springs on ebay and ordered them. Might try that if nothing else pans out.

Oh, btw, using Type F ATF for trans/primary fluid.

cheers,
JW

[tmwmoose]

back in 73 and again in 83 I used the aftermarket single spring nothing else was working and I used like a 10-40 motor oil.I thought I saw a aftermarket pressure plate and spring set up for the ole iron head .It seems like it was some time ago maybe 10 years+ but I remember wishing it was around back in the day I had XLs

[Burnout]

How is the clutch push rod adjustment set?

You can have freeplay in the cable and none on the pushrod if it not adjusted correctly.

I prefer the dual springs, you will notice they are wound opposite directions to counter twisting under compression.

Just checking that you have sleeves under the pressure plate on the studs?
Have you checked the length? (3 different lengths available) New nylocks on every reassembly?

[wreck74]

Run the same oil 60wt. in the engine and primary/transmission, ATF is way too thin for a wet clutch.

[tmwmoose]

Run the same oil 60wt. in the engine and primary/transmission, ATF is way too thin for a wet clutch.

Not that I care a bit for ATF , but this is interesting why 60wt ? what does it do for a wet clutch ?

[Burnout]

Run the same oil 60wt. in the engine and primary/transmission, ATF is way too thin for an Ironhead trans.

TIFTFY

Sport trans lube or Harley Formula+

Unless you have an early motor with a transfer valve then you should use the same oil that is in the motor because it gets mixed.

[Burnout]

Run the same oil 60wt. in the engine and primary/transmission, ATF is way too thin for a wet clutch.

Not that I care a bit for ATF , but this is interesting why 60wt ? what does it do for a wet clutch ?

Makes it stick and drag more when cold.....

[tmwmoose]

Run the same oil 60wt. in the engine and primary/transmission, ATF is way too thin for a wet clutch.

Why are the clutch plates on a the 1000cc XL wet clutch so much thinner with less surface area and higher spring rate than the smaller 900cc motors dry clutch which have much more surface area and lighter springs?

[nibroc]

JW-----
          your 78 is different than my 68 and 59---mine are supposed to be dry but I run barnett extra plt kits wet or dry in both goin on 30 or so yrs completely wet ---sport trans fluid and harley + fluid are the same---mine do not slip at all and I run em wet and trannys are andrews gears complete---sport trans no longer made became harley + a few yrs ago---barnett makes a kit for your 78 and it will not slip even w/big motor--60 wt oil is too thick for your primary even though it lubes the tranny also----JMMHO son

[JW113]

The clutch cable is adjust per the book, and the adjustment screw is ~1/8th turn loose from zero lash. But I'm going to pop the cover and give it another 1/8 just to see if that helps any.

A couple more pieces of info. The clutch and steels are new, made by Alto. I have all three lengths of stud spacers, and when I installed the new clutch pack, measured and used the spacer set that gave me the correct clearance between drive plate and release disk.

I have a 23T trans sprocket, so maybe this is a factor? I use and like ATF in primary (and trans for XL) in all my bikes. To me, ATF is ideal for H-D application, as it is formulated for the same environment, i.e. friction clutches and transmission gears. Never had a problem with in the decades that I've been using it.

As far as the clutch operation itself goes, it's perfect other than the slip at full throttle in 4th gear. The release/engagement is smooth, it does not creep or walk in gear at a stop with the clutch pulled, and it easily pops into neutral from 1st or 2nd at a stop.

I think the added load of a 23T sprocket is making it want more spring pressure than stock. Nibroc, I'll look into that extra clutch plate, that seems like a good idea. I also just received a set of NOS inner/outer springs from Barnett HD, will likely give that a try. And also, try the next shorter set of stud spacers to see if that helps.

So definitely have some knobs to turn to try and dial it in better. Thanks for the replies!

-JW

[JW113]

Well golly-gee. It turned out to the release screw adjustment. I pulled the inspection plug and checked it, was about 1/4 turn too tight. I backed it off to 1/4 from zero lash, took it for a spin, and clutch locks up tight now. I think I might know what happened. It was dripping trans oil from the primary cover gasket. I had been using a paper gasket, but replaced it with one of those James thin metal w/ silicone bead type. The gasket itself is thinner than the paper one, so of course this took out the clearance on the release screw and I didn't think to recheck it. Hey, ya learn something every day!

-JW

[Hossamania]

We like simple, free fixes!
Goes right back to the old saying, what was the last thing changed or worked on before it started acting up?