V-Twin Forum banner

Drive Belt Adjustment

29K views 17 replies 16 participants last post by  RB Jones 
#1 ·
I don't have a Harley tension tool but I'm wondering if there's another way to check the belt tension. The reason I'm concerned is when I ride with my wife I get a oil leak from the transmission drive sproket. When I ride alone I don't so I'm assuming the belt is too tight and pulling on the sproket when we are two up. I have added air to the shocks and that dosn't seem to help.

I would just loosen it up but I have heard not to get it too loose. The Harley shop set the tension (where it's set now) when they put on a new rear tire for me.I have checked other bikes in the showroom and they feel just as tight as mine.

Anybody got a neet trick for adjusting these? Can they be set too loose and how loose is too loose? If it were chain drive it wouldn't slip no matter how loose it was so I'm wondering if this belt is the same.
 
#2 ·
deanz02 said:
I don't have a Harley tension tool but I'm wondering if there's another way to check the belt tension. The reason I'm concerned is when I ride with my wife I get a oil leak from the transmission drive sproket. When I ride alone I don't so I'm assuming the belt is too tight and pulling on the sproket when we are two up. I have added air to the shocks and that dosn't seem to help.

I would just loosen it up but I have heard not to get it too loose. The Harley shop set the tension (where it's set now) when they put on a new rear tire for me.I have checked other bikes in the showroom and they feel just as tight as mine.

Anybody got a neet trick for adjusting these? Can they be set too loose and how loose is too loose? If it were chain drive it wouldn't slip no matter how loose it was so I'm wondering if this belt is the same.
I don't have any neat tricks for you, as mine's still in spec - but I bought the tool from Hd to do it myself. Cost $20.
 
#4 ·
Hows your tranny dipstick look? Chrome peeled on my orginal, HD quality. I must have been abusing it. Tranny seal is leaking. Though I doubt that thin little chrome did it, but never know. Replaced with Bakers.
 
#5 ·
An Old Harley mechanic once told me that if you can twist the belt to vertical (straight up and down) then it's adjusted correctly. This was back in Evo days so I don't know if it holds true with current belts, but this guy is an excellent mechanic and I trust his judgement.
 
#6 ·
kevdog442 said:
An Old Harley mechanic once told me that if you can twist the belt to vertical (straight up and down) then it's adjusted correctly. This was back in Evo days so I don't know if it holds true with current belts, but this guy is an excellent mechanic and I trust his judgement.
My dealer says if you can twist the belt to vertical, 90 degrees, it is LOOSE. If you can NOT turn it to verticle, leave it alone. Get the tool, it's under 20 bucks. Keep it in spec and you won't go wrong.
 
#8 ·
deanz02 said:
Thanks everybody. I guess I will buy a tool.

The tranny is not too full ( checked it level, hot) and it's for sure coming out of the shaft seal, not the vent.
It's more probable that it is your shifter shaft seal leaking and not the mainshaft. Get a small telescoping dental mirror and get a look at the bottom side of the shifter shaft and around the clevis. My seal is leaking for the second time. First time repaired under warranty and lasted about 12k miles. This time I ordered a gasket kit and shifter shaft seal from Cometic and I'm going to do the repair myself over the weekend. At least a quality seal will be in there when I'm done.

Oh and 3.37 gearing to make the labor worthwhile.:D

For what it's worth, I adjust my belt tension to 5/8" cold. That way when the pulleys heat up the tension on the belt will be just right. Not too loose, not too tight. IMO, the MOCO's spec of 3/16"-1/4" cold is wayyyy tight especially after the pulleys heat up. It's so tight you can pluck it like a guitar string.
 
#9 ·
It looks like the shifter seal is leaking on mine too.
 
#10 ·
Geezer-Glide said:
My dealer says if you can twist the belt to vertical, 90 degrees, it is LOOSE. If you can NOT turn it to verticle, leave it alone. Get the tool, it's under 20 bucks. Keep it in spec and you won't go wrong.
This is what I was always told for a good pre ride check. Quick and easy way to tell if it needs attention.
 
#11 ·
I adjusted my belt to specs according to the manual, and thought it was just too tight. Took it to a GOOD Harley dealer to see what he thought, and he promptly loosened it to almost what it'd been before. His opinion, (and I agree) was that the factory figure was just too damn tight.

Right? Wrong? I dunno, but I know I'm a lot happier now!
 
#12 ·
Nomad55 said:
I adjusted my belt to specs according to the manual, and thought it was just too tight. Took it to a GOOD Harley dealer to see what he thought, and he promptly loosened it to almost what it'd been before. His opinion, (and I agree) was that the factory figure was just too damn tight.

Right? Wrong? I dunno, but I know I'm a lot happier now!

I had the same experience. I adjusted mine to spec with the tension gage after replacing my tire. While riding two-up on a hot day (90's), the belt was making "groaning" sounds. I backed off the adjusters a bit and the noise went away.

John
 
#14 ·
JRS said:
I had the same experience. I adjusted mine to spec with the tension gage after replacing my tire. While riding two-up on a hot day (90's), the belt was making "groaning" sounds. I backed off the adjusters a bit and the noise went away.

John
I'm glad you added this post John. I just put new sneakers on my bike and using the HD drive belt tension tool adjusted it to the shop manual spec of 1/4"-3/16" with the bike on the Rivco center stand. (rear wheel in the air). I started getting the groan once it fully warmed up. Loosened it to 3/8" cold and the groan is gone.

Jeff
 
#15 ·
Anybody got a neet trick for adjusting these?
Well, some of you may laugh at this.

I was getting a new tire mounted on the rear wheel a few weeks ago and it got done a day earlier than expected. I hadn't gotten to the dealer yet to pick up the proper tension gauge yet. I wanted to get the bike back together so I looked around for what I had on hand.

The bike was up in the air on the lift. I put my wife's bathroom scales on a floor jack and rolled it umder the belt. I had a pice of 1" X 2" wood laying around, about 8" long. I stood the 1X2 on it's end so it was between the bathroom scale and the belt and I pumped the jack up until I had a 10 lb. reading on the scale. I made my belt adjustment using this method.

The next day after I had purchased the H-D belt tension gauge I checked my belt. There wasn't enough difference to make it worth while to change the setting. Been riding for about a month and everything seems fine. I checked the belt again after a few hundred miles and it's still good.
 
#16 ·
You need the tool to adjust it correctly.
With the bike cold on the ground without a rider on it. In neutral mid way between the sprockets on the bottom side of the belt.
With 10 lbs. deflection you should move it 5/16 to 3/8
Never bend one of these belt backwords it will weaken the belt and shorten the life.
 
#17 ·
Just a word of caution to anybody relying on any of this info. Be aware that there are different spec's for different models and years. If you want to do it right, get the spec's for your year and model bike. For instance, the belt on softails is checked at the top strand (or at least it was 3-4 years ago, haven't seen a service manual since then on softails). All other bikes are checked at the bottom strand. Measurements vary from 1/4-3/8 to 3/8-1/2 also. Just like the primary chain, it should also be checked at the tightest spot and when cold. Sometimes there are differences.

The belt should also be checked with wheels on the ground and load on the shocks not while the bike is sitting on a jack-up lift with rear wheel hanging. I have always added 1/4" to the upper measurement to simulate rider weight. It's worked for me since belts were put on the rear.
 
#18 ·
I obsessed over the belt tension, too. With 21,000 miles on the bike and a trip coming up I bought the tool (had to modify the piece that pushes up the the belt slightly to fit into FLHRCI belt guard) and set belt exactly to spec. in the manual with rear wheel off the ground. Seemed a little tight to me, too, especially when I checked it on the jiffy stand. But I left it where it was. Took it on a 1,650 mile ride with my wife. Has worked perfectly. Went in for my 5,000 last week and the dealer said it was OK and didn't touch it.

I don't think belt tension will have anything to do with a seal leaking when a passenger gets on. If the seal leaks, its going to leak all the time. You need to check the primary cover bolts. They tend to back off naturally over time and you can get a little seepage that the wind can drive back and make it look like it's coming from somewhere else. Torque them to spec. I had a couple of drops of oil on the ground on the trip and borrowed an allen wrench from a dealer and snugged up the primary cover bolts and all was OK. Always look for the most obvious and easiest solution before tearing into cases, gears and bearings.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top