Changing oil in stock shocks
4th Gear
Joined: Jun 2009
Posts: 8
Likes: 0
Changing the shock oil is really easy, I did front and rear on my ultra. I used a vacuum cleaner on the front so I didn't have to remove the fairing and radio box, just suck on the air line and it will pull the oil right up into the front shock.
On the rear I pulled the shock and put it in a lever I made from a 2x4 on my bench. Airline fitting down and pump gets the oil out, fitting up and connected to a tube and funnel of oil will blow air into the oil when compressed, then suck oil in the shock when released.
I used SE 10 weight shock oil, and it rides much better with half the air pressure now.
On the rear I pulled the shock and put it in a lever I made from a 2x4 on my bench. Airline fitting down and pump gets the oil out, fitting up and connected to a tube and funnel of oil will blow air into the oil when compressed, then suck oil in the shock when released.
I used SE 10 weight shock oil, and it rides much better with half the air pressure now.
Road Master
Joined: Nov 2007
Posts: 820
Likes: 1
From: Sunny Saint Petersburg Florida
I used the above links and put 15w belray fork oil. Made a big difference. No lolnger have to put a lot of air in the shocks when ridin 2up. Changing the oil is easy if you have the mity-vac pump.
Tourer
Joined: Jan 2009
Posts: 325
Likes: 0
From: Tennessee
What kind of lowering kit do you use? That may be the route I have to go to get the ride I want. I've heard you have to be careful with some kits that will let the tire touch the fender.
Road Warrior
Joined: Jan 2005
Posts: 1,416
Likes: 27
From: Northern Part of the Great Lone Star State
pringle this time around
It does however change the angle of the shock which I have questioned but seems to be satisfactory at this point in time...
Million dollar question I suppose would be would the average joe be able to tell the difference with the minor angle that the various companys offer vs. the engineered design that H-D has decided on while riding down the road???
My Butt can't tell...
It does however change the angle of the shock which I have questioned but seems to be satisfactory at this point in time...
Million dollar question I suppose would be would the average joe be able to tell the difference with the minor angle that the various companys offer vs. the engineered design that H-D has decided on while riding down the road???
My Butt can't tell...
Tourer
Joined: May 2009
Posts: 332
Likes: 0
From: Smithfield, NC
You might want to contact Belray and ask them about the consequences of using fork oil in your rear shocks. The oil in a rear shock heats up a great deal more than in a fork and every oil maker out there will tell you it is very dangerous to put fork oil in a rear shock. You're going to get on a very bumpy road some day and potentially loose all viscosity.
Tourer
Joined: May 2009
Posts: 332
Likes: 0
From: Smithfield, NC
I bought a set of 12" shocks off an 09 street glide to lower my Ultra a little. When they arrived, the dealer that took them off before they left their shop hadn't plugged them. Some of the oil had leaked out. Thus began my journey into the world of rear shocks.
I've read the threads above and there is a lot of good information, but the one thing that is hard to nail down is the quantity of oil in an 09 12" shock. There are lots of numbers out there and depending on the model year of the shocks, they may all be correct. I started with 10 oz and began to work my way up. I think I have about 11.5 oz in now. Still have issues with the bike bottoming out.
I have talked to 3 Harley shops and none of them can get any numbers from Harley on the quantity of oil to use in rear shocks. The only way to determine the correct amount is to drain a new shock to see what it holds.
The shock is going to bottom out at a specific position or length. The oil-air ratio is important in that too little oil leaves too much space for air and with maximum pressure in the shock when it's sitting on the stand, the pressure when the shock bottoms out (full compression) could be greater than the shock can handle because of the increased air pressure. On the other hand, too much oil could cause a hydraulic lock with the same overpressure problem.
I'll probably try some 7.5 Wt shock (not fork) oil next to see how that helps.
I've read the threads above and there is a lot of good information, but the one thing that is hard to nail down is the quantity of oil in an 09 12" shock. There are lots of numbers out there and depending on the model year of the shocks, they may all be correct. I started with 10 oz and began to work my way up. I think I have about 11.5 oz in now. Still have issues with the bike bottoming out.
I have talked to 3 Harley shops and none of them can get any numbers from Harley on the quantity of oil to use in rear shocks. The only way to determine the correct amount is to drain a new shock to see what it holds.
The shock is going to bottom out at a specific position or length. The oil-air ratio is important in that too little oil leaves too much space for air and with maximum pressure in the shock when it's sitting on the stand, the pressure when the shock bottoms out (full compression) could be greater than the shock can handle because of the increased air pressure. On the other hand, too much oil could cause a hydraulic lock with the same overpressure problem.
I'll probably try some 7.5 Wt shock (not fork) oil next to see how that helps.
You are however correct in stating that too much oil can hydraulic lock the shock or blow out the seals. This is because fluids are not compressible.
Tourer
Joined: Jan 2009
Posts: 325
Likes: 0
From: Tennessee
Actually, a greater volume of air would do just the opposite. Air is compressible and according to Boyle's law PV=Constant, as the volume increases, the pressure decreases.
You are however correct in stating that too much oil can hydraulic lock the shock or blow out the seals. This is because fluids are not compressible.
You are however correct in stating that too much oil can hydraulic lock the shock or blow out the seals. This is because fluids are not compressible.
In the end, I worry too much and Texas Bowhunter is right, it's not rocket science.
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