2013 Yamaha Wet Friction Brake Noise
 

After changing the transaxle oil with 2 quarts of Yamalube Friction
Modified Shaft Drive Gear Oil SAE 80-90 API Service GL-4, GL-5 the brakes now make noise when pressing hard on them to bring the cart to a stop. The brakes did not make any noise beforehand. I have 18K+ miles on this cart since buying it new from TV. I noticed a very small amount of non metal material in the old oil. Any thoughts or suggestions?

We add a anti friction additive and that will get rid of the noise. The color of the gear oil generally dictates its replacement. We check the condition of the gear oil at every service.

Go to an auto parts store and pick up a couple of ounces of friction modifier and add it to the differential fluid. In theory, you shouldn't have to do this as the Yamaha gear oil already has friction modifiers in it. You may also want to change your differential fluid more often. Check your owner's manual for the recommended change frequency. Please report back as to whether adding additional friction modifier addresses the noise issue.

Try driving it while riding the brakes. The noise should go away.

Tried replacing 2 oz of gear oil with friction modifier, problem got better but was still there. I’ve then replaced 8oz (total) of gear oil with friction modifier. There is a marked improvement however a hard stop will make noise just before the cart comes to a full stop. Any ideas?

We use a very good product for our customers, but its pricey, but works very well. If you go with a less expensive generic type, plan on adding more product to get rid of the noise.

I'm not understanding why the OP has a problem. It sounds like he put in the exact gear oil specified by Yamaha for this application.

Does Yamaha put additional friction modifier in this gear lube before it leaves the factory? If so, exactly what?

Follow up from the OP for those who have interest in knowing the solution. I finally got it working again.

I connected with an experienced Yamaha dealer mechanic not from TV. He advised they see this issue quite frequently. The solution was to flush the transaxle again after driving it for a short period of time with the brake noise. He recommended replacing with 48 oz of high-quality gear oil mixed with 16 oz of friction modifier.

I purchased 4 Genuine Ford Fluid XL-3 Friction Modifier Additive (4 ox each) and 2 Valvoline VV831 1 Quart High Performance Gear Oil from Amazon.

Using my air compressor and floor jack, I drained the transaxle. I used the floor jack to position the cart numerous ways and then the compressed air to drain as much of the old oil as possible from the trans axle.

One thing I did learn along the way is Yamaha has discontinued making the old style trans axle. You can no longer buy a replacement unit. If there were ever a problem most likely it would be difficult to obtain parts and most certainly a costly repair. The trans axle would need to be removed from the cart, the clutch removed and the case split in two. Lots of work. I have over 20k miles on my 2013 and wondering how long the wet friction brake pads will last. So far no one I have talked with has replaced them. If anyone knows different or has some experience with this your feedback would be appreciated. Perhaps this is something to consider when deciding to buy an used cart or getting a new one that does not have this style braking system.

You didn't really have to go through all of that, but good to hear you got it fixed.

You were also told correctly, parts for that rear end are being discontinued and the remaining parts are being sold at astronomical high prices. 07-14 yamahas could be pricey to repair. The differential has been really good with few issues unless proper service has not been performed, or when an issue is not dealt with in a timely fashion.

Can the brake pads be replaced without replacing the rear end?

Its not pads, its friction discs. I haven't seen one wear out yet. Ive had some 07-08s open lately and the discs look great. So they will last a very long time.
When it does come up for replacement, you don't need to change the whole differential.

If anyone is being told they need the brakes replaced on those units, be sure to get a second opinion.