Underseat Coolant Bottle Relocation Questions

My dealer was getting ready relocate my coolant bottle underseat today.. Mind you my bike is his first experience with the kind of R3 performance mods done on this forum. He had two questions:

1) First he was concered about the system's ability to draft coolant through the longer hose... I said no problem... At least a dozen guys have done this and run thousands of miles with no problems.

2) Right now the bottle is above the radiator and provides gravity feed should the cooling system develop a leak and loose the ability to siphon from the bottle. If the bottle is underseat, it will be below the radiator and may loose its ability to feed the cooling system in the event of a leak... He bounced this off of his Triumph Engineering Support guy (Atlanta I guess) and of course he didn't have an answer either (no surprise)... Support guy also stated he didn't know wether or not there would be a warranty issue if the bottle was under the seat and a problem as described above developed.... He said he would be most comfortable if the bottle was placed where gravity feed would be provided... Well I sure as sh&%t ain't gonna mount it on the handlebars.... What we are looking into is an alternative bottle from an old Triumph Trophy my dealer has in the shop. It appears it may fit under the tank where the air ducting was removed for the Unis... We will try this on Monday.... So bottom line, do you guys think this gravity feed thing is a ligitimate concern or not...

Thanks,

Mike....

hombre said:

Mike

I've never had any problem with the bottle underseat in just over a year. The trick is getting the coolant level right, but as long as your hoses aren't blocked it becomes self-leveling. Also, my dealer worked with the bottle under seat for my warranty transmission repair... no questions asked.

hombre

Click to expand...

Did you just use the existing bottle and move it under the seat , or purchase something else for the job :?:

sully said:

hombre said:

Mike

I've never had any problem with the bottle underseat in just over a year. The trick is getting the coolant level right, but as long as your hoses aren't blocked it becomes self-leveling. Also, my dealer worked with the bottle under seat for my warranty transmission repair... no questions asked.

hombre

Click to expand...

Did you just use the existing bottle and move it under the seat , or purchase something else for the job :?:

Click to expand...

I trimmed the stock coolant bottle mount's, and located it in the original air filter housing. Perfect fit and works with no problems, a lot of others are running the same way I believe... 8)

No problems here either. And my bike runs cool...fans hardly come on unless in the worst traffic...

Thanks for that guys :lol:

talltxguy33 said:

I've got mine under the seat as well and never had any problems.

Click to expand...

+1, but I still check the level in the radiator by removing the cap every

once in a while. In about a year and a half no problems. Like your dealer

I had the same concerns when I first did the mod, but found they were unfounded.

coolent

Under the seat for two years without any problems.
rockenrobert
gotta see the world, it will only take a mintue

As long as the end of the hose is under the coolant level in the overflow bottle it will suck coolant back no problems. If it is above the level it will suck air.

I have designed cooling systems for years... and have a pretty good understanding of how they work.. and how to alter them for just about any sitution. I even write web site based (for example of one see here... http://www.streetrodstuff.com/Articles/ ... ggestions/ .... and media (magazine) based tech articles on cooling (and other techy stuff) professionally.. mostly in the high performance markets.. but also have some aircraft articles as well. I offer my ideas on this... if anyone wants to try this.

First information. The Rocket III cooling system employs a downflow radiator. Because your coolant naturally expands when heated.. you need somewhere for that expanded coolant to go. This is where the "overflow" bottle comes into play and the perverbial "hot" and "cold" level marks commonly found on any bottle.

If you fill the radiator full to the cap... and don't allow any expansion space the expansion when the coolant pool expands will violate the cap (because you cannot compress water!!) and the pressure at the cap will always override the cap's pressure rating! By employing the vented cap.. this allows the coolant to expand to the bottle.

If you look at older style downflow radiators.. there was a large holding tank on top. This tank did NOTHING for cooling, but when you filled the radiator.. ... one left about a 1" space in the top of the tank when filled... to allow for that expansion compression. Hence.... no overflow needed.

If the Rocket had a top tank.. it tooo would need no expansion tank with a non-vented regular pressure cap in tact. The coolant in the system would ebb and flow inside the top tank with natural expansion.

Now.. the reason the overflow bottle is designed into the Rocket's cooling system is because the radiator does NOT have any expansion tank... and moreover they MUST need the top of the radiator footprint to adequately cool the Rocket in severe situations. If one dropped the coolant level in the radiator about 1/2" would this suffice for a "natural" expansion area and moveover eliminate the overflow tank completely! I would say in most cases this could be done.. but I have not tried it... and would have to play with it to see just how much of an effect this really has????

So, back to the coolant bottle. In my opinion.. the coolant bottle could be easily downsized to another model or even footprint as long as the cap of the overflow is kept above the "pool" level of the coolant when fully expanded. Otherwise... it will expell on the floor! So, there are choices out there for easier and prettier overflow bottles.

For example, something like this pictured here.


or...something like this mounted externally on a downtube somewhere??



Here are a couple of "universal" models to think about.



The bottom line here is that you can use almost ANYTHING .. even a wiskey flask if you can connect it ... and it has enough expansion space below the "pool" level when expanded. And, you can really leave the overflow empty (when at cold levels) and reduce the overall expanded "pool" to just take up room when hot. So, you would NOT see any coolant in the bottle when cold. This does NOT affect the volume of the pool in the radiator.... or it's ability to cool.

The way to find out how much expansion volume is needed it simply take the overflow and measure the difference in volume between the hot and cold lines! This will be just about all the volume you would need for an effective overflow tank regardless.

Just toooooooooooo much information.. I know! But, interesting idea I think all will agree!

I think I will try a small billet "hotrod" tank somewhere in the near future and report back when accomplished.

Steve,

A terrific explaination... Many Thanks.... Never really understood this stuff until now.... As you said, we are going to keep the bottle above the radiator..... The Triumph Trophy bottle did not fit under the gas tank.... Looks like the Daytona 955i bottle will... There my be a spare one of these around the shop we can use... Thanks to all for your input... I will post pictures on the undertank coolant bottle install when done...

Mike....