[DjfLoYd]

I've heard some unsupported, unconfirmed and possibly just vicious rumours that the 04 is having a problem with the rear shock overheating. Apparently with the pipes running nearby, the shock is exposed to the heat of the pipes and after prolonged use the rear shock's performance is degraded. :dunno

Personally I'm pretty sure Yamaha would research the product more thouroghly before releasing it and would have picked up such a problem should it exist. If not I doubt they would admit to it now. So I guess all you new 04 owners better give us the heads up once you've put some miles on the baby. :fact

 

[Valerossi]

Well, I'm not sure about the 'O4, but even with the 'O2/'O3 stock rear shock, they seems to have heat problems when people ride for an extented period on the track. I read a few magazines issuing that stock rear shock problem when they did those reviews back then when the 'O2 just came out.

But on the street, I never seem to have that problem, even when I ride all day.

 

[Fate]

Stock rear + front suspension oil is cheap low quality stuff. Use oil from Ohlins or other well known suspension companies. Much better than stock crap.

 

[technobug]

Stock rear + front suspension oil is cheap low quality stuff. Use oil from Ohlins or other well known suspension companies. Much better than stock crap.

Ummmmmm....................actually not true. Stock OEM lubricants and fluids are actually of VERY high quality and far surpass many after market products. There is a perception that after market is better because so many people use it, but this is usually only because after market product is cheaper.

I can tell you that factory race teams use Kayaba and Showa hydraulic fluids just like OEM.

Oh yeah, one more thing. If there is a heat fade issue, I guarantee it has nothing to do with the shock oil. I have nothing against Ohlins, but I bet that if you were to switch from OEM to Ohlins shock oil, your heat fade issues will get worse.

 

[martinc]

Well,my Ohlins used to super-overheat last year...guess what;its was done.

Rebuilt-time it usually means.

But they all produce heat,its just that most riders dont think about touching their shocks after a ride...and what would be a normal working temp for those is a mystery to me.

 

[Vahakn]

Well,my Ohlins used to super-overheat last year...guess what;its was done.

Rebuilt-time it usually means.

But they all produce heat,its just that most riders dont think about touching their shocks after a ride...and what would be a normal working temp for those is a mystery to me.

:iamwithst well said!!!

 

[Fate]

Strange. My Showa shock overheated once, a few years back. The guy who was riding with me was on an Aprilia RSV-R and had no problem. I didn't get it. His rear cilinder exhaust was running right next to the Ohlins shock! So I changed damper oil and had no problem since.
For some: overheating = damping was completely gone! Rear end was going up and down like a rubber boat on the waves.

 

[martinc]

I"ve talked to a specialist yesterday and he told me that its pretty common for FORK oil to run into 180F!!

Another bit of info he gave me is that for those having problems with shock,changing the oil for something colder is the way to go.

Same thing applies to brake fluid;dot4 is cheap,dot 5 is cooler.

 

[echo7]

Believe it or not you should not replace oil in shocks It is not recommended unless there's a critical need for it.

 

[Scooby]

You go ahead and put your DOT 5 in your bike and watch all the rubber ooze out onto the ground!

 

[technobug]

I guess I better explain something. Typically, the temperature at which a modern hydraulic fluid breaks down is much higher than the highest operating temp of a shock absorber. The main cause of what is perceived as "fade" is actually piston blow-by. Shock pistons are typically made of steel because the expansion rate of steel is low and this keeps the piston diameter consistant. Shock bodies are typically made of aluminum for the heat dissapation properties. Now this is where the problem lies. The heat expansion rates of steel and aluminum are very different. The aluminum grows much faster than steel. So as the shock heats up the body expands but the piston doesn't.

Another factor to consider is the different types of aluminum used. OEM shocks are typically cast aluminum because of the high production numbers and cost, where as most after market shocks use an aluminum billet body tube. Cast metal is much more porous than billet. The more porous the metal the faster the expansion rate. Heat dissapation is also less efficient.

Though the temp at which "shock oil" breaks down is rather high, there is some viscosity change at lower temps. Now these lower temps are at the high end of the operating temp however. Oil ratings are totally misleading. Oil "weight" really doesn't mean too much. One manufacturers 5wt. can feel heavier than another. True rating are made in Centistokes at a given temp. Typically OEMs use a much lighter fluid than some of the after market comps. The reason I believe this is better is because when the oil heats up and the viscosity starts to change the percentage of change is smaller when starting whith a lighter fluid. I guaratee that you get a much higher percentage of viscosity change with a heavier oil.

Sorry this got jumbled up toward the end. Getting tired of typing.

 

[erixR1]

You guys are kind of on a tangent with the fluid being the source of fade due to exhaust proximaty.

Technobug has the identified the problem, that being piston clearances. But what makes or breaks the shocks ability to minimize the 'blowby' is the seal used on the piston.

A properly designed seal that can account for the tolerance changes thru the full range of heat cycles will handle the job just fine.

The 'rumor' will be just that. More guys thinking it should, who tell his buddy who tells his buddy who has an internet connection. The OEM shock would have been designed with the exhaust in mind, so no worries.

Your only source of worries will come from Aftermarket shocks, where they may not know the full temp range.

I ran into this on my RC51. The OEM shock never faded, but its valving just sucks. So I put a Fox in. After just a few miles the thing had 0 damping, was just riding on spring. Talking with a Fox engineer, they were having the same problem on Creviers RC and knew it was an underated seal. They swapped it out and all was happy.

 

[martinc]

You go ahead and put your DOT 5 in your bike and watch all the rubber ooze out onto the ground!

What rubber...there"s not much rubber in my setup,that I can tell ya.

 

[ExHondaGuy]

Same thing applies to brake fluid;dot4 is cheap,dot 5 is cooler.

NEVER use Dot 5 brake fluid in a sport bike! It is silicone based, and not hydroscopic. Since the brake systems on sport bikes are not fully sealed, moisture can get in, and with Dot 5 fluid it can form water "bubbles" that can seriously corrode your brake system and cause heat-performance problems.

I use Dot 3 high temperature racing fluid. Don't make the mistake of assuming that Dot5 is better than Dot4 is better than Dot3. It doesn't work that way.

 

[Scooby]

If you have no rubber in your brake system you shoud run out and get that thing patented. I dont think having the cups in you master cylinder turning to goo at a buck fifty would be to fun.

 

[martinc]

It would be fun to see you guys having a discussion with the enduro guys I"ve talked to yesterday;

They claim to be using the dot5 for 10 years without any problems.

Not that I"m crying BS though...my brake fluid knowledge is very limited.

 

[technobug]

I ran into this on my RC51. The OEM shock never faded, but its valving just sucks. So I put a Fox in. After just a few miles the thing had 0 damping, was just riding on spring. Talking with a Fox engineer, they were having the same problem on Creviers RC and knew it was an underated seal. They swapped it out and all was happy.

Absolutely correct. Fox fixed that problem with the RC51 shock by special machining an o-ring gland into the piston and energizing the standard hard DU piston ring with a Disogren o-ring. Allows piston ring to grow more with temp increase to maintain the seal with cylinder.

The 51 was a pretty special case though. The pipe that ran next to the shock was the header pipe from the rear cylinder. Being that the "04 R1 is an inline 4, the exhaust temp by the time it reaches the area where the shock is should be considerably lower than that of the RC51.

 

[martinc]

technobug,you work for which racing team again?

 

[Scooby]

Last time I checked an enduro bike was different from a street bike.

 

[Scooby]

Another thing, the top of the brake resivour says Dot 4 only, I guess it's alright to ignore the manufactures recomendations. Just remind me not to test ride your bike
I don't mean to come across all pissed off or anything, but like exhonda guy said Dot 5 is silicon based and that stuff eats rubber. if you have dot 5 i really would rebuild your system, it would suck some big kahunas to loose the front brakes at any speed.