08 Trannys are not going to change so I have read. I rode mine for about 500 miles with Redline and the tranny just shut up. It was very sudden and strange. There is a fifth gear whine but I really have to listen for it.

 

I could fine the Redline gear oil in my area but I picked up some
Mobil 1 Synthetic Gear Lubricant LS 75W-140
I hope it does the same thing...has anyone tried this?

 

Personnally and from what I've learned and heardover the years the Redline or Bel Ray may be a better tranny fluid, but hey post on here how the Mobil works out for you. Their synthetic motor oil is very good stuff, both the oil for bikes and cars. Good luck

 

I used the Mobil 1 and the Redline. Mobil 1 helped a lot and is very good, but Redline quieted it more. Redline is had to find in a store. I order it from Summit Racing and have it in two days.

 

You are right...the transmission will not be changed. But the machining tolerances will be held closertocorrect this problem.

 

I live in upstate NY so it will be a few more weeks before I can try it...but I'll let the forum know how the Mobil 1 75W-140 works.

 

First, there should be no problem with thicker oil in a gearbox constructed with needle bearings. If it used sleeve bearings there might be a problem with the oil working its way into the bearing and providing proper lubrication.

Next, I used Royal Purple 75w90 in my '96 RK and it went 106k miles without any tranny service, except maybe two pawl adjustments. It never saw HD fluid except out of the factory. It wasn't an '07, but they are fundamentally the same from a lubrication standpoint. The 75w90 gear oil has the equivalent viscosity of a 10w30 (approx.) motor oil, while the 85w140 is the equivalent of about a 20w50. This is a quote from Spectro Oils about using their 85w140 in a Big Twin:

"A Superior GEAR/ TRANSMISSION LUBRICANT designed to reduce clunks while shifting a Harley Davidson motorcycle transmission (no small task) and reduce whine in fourth gear. The 85w140 viscosity (roughly the equivalent to a 20w50 motor oil) dramatically helps shifting when hot. For use in all 'Big Twin' models, any year, without restriction."

 

Here's an update that gives little in the way of news, but I'll pass it along anyway. I received a call from my local dealer's service manager, who was responding for the owner who promised me answers on the noisy-tranny issue. Apparently, HD's position on the various noises produced by the 6-speed tranny is normal and not a sign of problems that will bite us later. I tend to believe this, as I've had transmissions that were noisier than this that never failed (e.g., Muncie M21 on my '66 Corvette), and have already taken steps to rectify it by experimenting with various fluids. First, I changed the primary fluid to 20w50 Castrol GTX (fossil engine oil) and Royal Purple 75w90 in the tranny, which did seem to make a moderate difference with the clattering. Then, in response to feedback here, I recently changed my tranny fluid from Royal Purple 75w90 to RP 85w140, which made a dramatic difference.

He also mentioned that the noise exists in all 6-speeds, not just touring models, and that they are more noticeable in the big bikes because the fairings tend to reflect the noise toward the rider. You would think windshields would do the same on any bike, however.

I asked the guy if HD had a problem using the thicker gear oil and he said "absolutely not," and that if it quietened the tranny down that I should continue using it. So, that's my plan, since although it isn't totally quiet, it is quiet enough to no longer detract from the many virtures this bike has to offer. As far as I'm concerned, the tranny noise is no longer an issue with me, although I will be watching the messages here for any new developments.

 

Thanks iclick...
One question on your experiments...how many miles did you have onyour bike before you went to the 75w90 and then to the 85w140. I have 2500 on mine and plan on changing to the 85W-140 this spring. I was wondering if using the stock oil for these 2500 miles,did enough damage where now even the heavier oil won't help.

 

I've got an 07 Softail Custom with a small windscreen and I hear the 5th gear very plainly. It's not a constant whine, but sort of a fast WOWOWOW sound.
This weekend I put Redline Shockproof Heavy in the tranny and after about 100 miles the noise is quieter and the shifting is much smoother too.