K75, T,C,S vs. K75RT Radiator-Here are the Dimensions

[gone_ape]

I'm changing my K75 RT to Standard spec. So if you're like me, there's been a  struggle with finding dimensional info for the 2 different K75 radiators.  Here be hopefully a helpful bit of visual to help others when swapping radiators from the Standard (T,C, and S too) to K 75 RT or visa-versa. Some have said the RT radiator is the same as a K100's....so this may help others when searching the internet for such parts. The heights of the two are identical, and only horizontal width and core thickness seem to be different.   
PLEASE NOTE these measurements are approximate (made with a tape measure) and not NASA standard quality...

[gone_ape]

Another pic with the fans attached and bare...

[Martin]

 :2thumbup:Much appreciated, information like this can be extremely helpful. If you still have access to the radiators I was wondering if you could determine the capacity of both of the radiators. My workshop manual does not differentiate between the various K75 models, only between the 75 and the 100. If you can't I still appreciate your effort.  :clap:
Regards Martin.

[Laitch]

Here be hopefully a helpful bit of visual to help others when swapping radiators from the Standard (T,C, and S too) to K 75 RT or visa-versa..

  :2thumbup:

[gone_ape]

Yes, I will check on capacities, it will probably be the weekend before I can get to it.....

[Laitch]

. . . I was wondering if you could determine the capacity of both of the radiators. My workshop manual does not differentiate between the

The Rider's Manual specs indicate the same capacity for both radiators and that seems likely. The heights are the same. They may equalize in volume because the RT is wider than the T/C/S but the T/C/S is "thicker" than the RT.

[Martin]

Laitch I thought they would be close but confirmation would be good.
Regards Martin.

[Laitch]

I thought they would be close but confirmation would be good.

It's understandable you wouldn't believe specs in the BMW manual, Martin, because you've already chosen Hell over belief in their plug wires. :giggles

[Martin]

Laitch when are you going to come over to the Dark Side. We have éclairs and profiteroles. Oooo Ha Har Har.
Regards Martin.

[Filmcamera]

Yummy

[gone_ape]

Martin, Here are the Totally-Backyard-Shade Tree-Non Scientific-Jethro results from my capacity volume tests for the two radiator types.


As a control, I removed both thermostats and sealed up all the ports except the filler. No hoses were attached. Burped the best I could, but there is always the possibility that an air bubble got stuck..I tried.


My standard for the test was a beaker filled with 64 fl. oz (1892 ml) of distilled water.  After filling/burping both, I measured  ***THE UN POURED FLUID*** left in each pour.  The results are as follows:Test Standard 64 fl.oz. (1892 ml)K75RT took ~26.5 fl.oz. (783 ml)K75 Standard/C/T/S took ~24.5 fl.oz. (724 ml)So an approx difference of ~2 fl.oz. (59 ml) in favor of the RT radiator.Again, just eyeballing backyard style testing...here's some photos.2 of the pics show THE UN-PORED remainder.

[Martin]

Thanks GA so I now need to fit an RT radiator to my S for the benefits of extra cooling.
Regards Martin.

[Inge K.]

I now need to fit an RT radiator to my S for the benefits of extra cooling.

Don't know if it's space enough for the wider radiator inside your fairing, but.........
If you want better cooling you should look for a 3 row radiator from a K100 before -90.
(in the pictures the the one for the RT is a 2 row, and for the other models a 3 row)
And change out the water/oil pump to the one that was in use before -90 on your model.
(the water pump is spinning faster).

[Laitch]

Thanks GA so I now need to fit an RT radiator to my S for the benefits of extra cooling.

You think 60ml additional coolant will make a discernible difference in performance, Martin? Bourbon, yes.  :yes

[The Mighty Gryphon]

Laitch, that extra 2 oz. of capacity could translate to an additional 8% of residence time in the radiator.  Additional, that is, if the extra time is spent in the tubes instead of the tanks.  8% is a fairly significant increase in high ambient situations.  It could make the difference between overheating or not.

Having said that, personally, I would put my energy into keeping the internal passages of the engine and radiator along with the fins as scrupulously clean as possible.  A few bugs or a bit of dirt can obstruct a lot more than 8% of the airflow through the fins.  Same thing for deposits coating the internal passages of the engine and radiator. 

When I got the Moby Brick, it would overheat at 30mph in ambients of 90F, not to mention what happened when I got stuck in traffic.  A good internal and external cleaning improved the cooling so that even when stuck in traffic the fan could easily keep the temperature under control in ambients nearing 100F.

Clean is cool.

[Martin]

Fellas, come in spinner.  :hehehe I've never had a problem with my cooling system I only used distilled water and OEM coolant and I change it every two years. I did a complete internal external clean a couple of years ago which was a waste of time except for peace of mind. The only overheating problem I've had is with the fuel. The fuel cooler I made works great at speed but does not work as well where I need it in traffic. When I acquire access to more machinery in June the Mark two version with more capacity thinner and more fins front and rear may fix the problem.
Regards Martin.