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K1100LT Fan replacement scheme
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Flying Duck
PsyKotic Waterfowl


Joined: 27 Jan 2005
Posts: 9945
Location: Bumf***, WA

PostPosted: Wed Sep 08, 2010 10:06 pm    Post subject: Reply with quote

supercat1 wrote:
nick, an option would be to upload your word document to mediafire.com and then post a link to it here on the forum. we would then all be able to dl it at will.

also, i know for a fact that those little computer fuckers can be not so quiet when run at full tilt all the time. my pc has space for 6 of them and with only 2 installed it is akin to a vacuum. 6 would be a wind tunnel i believe. but, at highway speed that sound will be lost by the wind noise anyway. in terms of how much air they actually move? well, if completely isolated they may move the quoted value, but in real life i doubt it.


Yeah, but if the radiator fan is going it's already generating a little pressure in there. (but directed up and back, not out the sides. My experiment will be to run them off of the fan relay so that when the Motronic kicks in the fan or I hit my fan switch it will turn all of the fans on.
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93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
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nickw
Big Brick Rider


Joined: 12 Aug 2010
Posts: 72
Location: Essex, VT USA

PostPosted: Thu Sep 09, 2010 6:54 pm    Post subject: Reply with quote

Thanks to those who wrote and suggested sites to upload the entire document. I will try that tonight.

Duck:

I am curious about the fan switch to manually kick the relay on, is there any issue with the Motronic being bypassed? I would like to add an alternative switch position but haven't clearly understood how best to wire in a switch. I have been waiting for some connectors i ordered to complete the installation and want to add an LED to show the fan is on so I won't forget and leave it on if I have a "Manual/Auto" function switch on the fan relay. I'm still a bit worried about turning the Motronic unit into a Moronic by frying its little brain.

How did you wire yours?

Nickw
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"It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650
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Flying Duck
PsyKotic Waterfowl


Joined: 27 Jan 2005
Posts: 9945
Location: Bumf***, WA

PostPosted: Thu Sep 09, 2010 7:27 pm    Post subject: Reply with quote

All you need to do is tap into the blue/yellow wire for the fan relay. Have the switch ground it to trigger the relay.

Several of us here have done it and no Motronic issues. The Motronic is just grounding that blue/yellow wire.

For RSs, I've made combo hazard/fan 3 position OEM switches for some people since an RS only has 3 switch slots.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE


Last edited by Flying Duck on Thu Sep 09, 2010 7:30 pm; edited 4 times in total
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nickw
Big Brick Rider


Joined: 12 Aug 2010
Posts: 72
Location: Essex, VT USA

PostPosted: Thu Sep 09, 2010 7:27 pm    Post subject: Reply with quote

I opened a mediafire account and uploaded my (updated0 fan story)

I think this is the link: http://www.mediafire.com/?63c73rojcr633dj

Good luck
_________________
"It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650
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drikko
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Joined: 20 Nov 2009
Posts: 1966
Location: Brisbane, OZ

PostPosted: Thu Sep 09, 2010 8:39 pm    Post subject: Reply with quote

That worked, well done! Great fix BTW, hope I never need it but have stored the file in case I do. Thanks for taking the time to write it up.

Cheers

Derek
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K1100RS '97
Laverda RGS 1000 '84
Jim Young Trailer Sailer 5.7M WB

DISCLAIMER:- Anything I say may have been when I was drunk so please don't take it personally.

'Bigamy is having one wife/husband too many. Monogamy is the same.'
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max
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Joined: 22 Aug 2005
Posts: 309
Location: NZ

PostPosted: Fri Sep 10, 2010 4:36 am    Post subject: Reply with quote

Thanks for the info, nick - great detail.

If anyone does use computer fans - and I'm not suggesting they're perfect for this either, they have their own problems, mainly waterproofing - you can use a reduced voltage to reduce the RPMs and noise... There will be a threshold at which the internal electronics "drop out" and it stops, but a three-terminal regulator (TO220 7808 for 8v would be easy) will reduce the noise a lot.
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Flying Duck
PsyKotic Waterfowl


Joined: 27 Jan 2005
Posts: 9945
Location: Bumf***, WA

PostPosted: Fri Sep 10, 2010 2:13 pm    Post subject: Reply with quote

Holy cow! I just found a computer fan that's 3.6x3.6x1.5" which should fit behind the LT side grills and moves 175 CFM! That's GOTTA make a difference. It pulls 3.1 amps. I'll probably give them their own fuse and relay since a pair will draw 6.2 amps.

http://www.heatsinkfactory.com/delta-pfb0912dhe-92mm-drastic-high-speed.html

I'm aware that they are not waterproof but I'm not sure that's a big risk inside the fairing. One way to find out...
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE
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AUSBRICK
Mad Brick Rider


Joined: 18 May 2007
Posts: 115
Location: MELBOURNE AUSTRALIA

PostPosted: Sat Sep 11, 2010 3:26 am    Post subject: EASY FIX Reply with quote

I did a 3 core with extended bottom brackets to make it sit more vertical lost the thermo fan altogether as I believe it reduces air flow .Cooling is so much more efficient that the bike only gets hot in very heavy stop start traffic in Aussie summer. I keep an eye on the temp and use the kill switch for long delays ,temp now stays low under heavy riding climbing steep mountains fully loaded on hot summer days , these conditions previously made it get very hot and it took a long time to come back down, Ps I dont do a lot of city riding but generally if its rolling it stays cool as do I.
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miKeinWIs
Mad Brick Rider


Joined: 29 Jun 2009
Posts: 143
Location: Birchwood, WI

PostPosted: Sun Sep 12, 2010 7:57 am    Post subject: Reply with quote

Nick,
Thanks for fan update.
I tapped the blue yellow wire in the box under the seat. Ran a wire to the handlebar switchs and mounted a lighted $4 auto parts store switch I had laying around. Switch lites when fan is on. Easy enuf for even me.
I inlayed and RTV'ed the switch into an available blank OEM switch. Someday may get a real BMW switch but this has worked so far all summer.
Good luck
Mike
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Bought 6/30/09 w/26,750 miles
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nickw
Big Brick Rider


Joined: 12 Aug 2010
Posts: 72
Location: Essex, VT USA

PostPosted: Mon Sep 13, 2010 6:51 pm    Post subject: Reply with quote

Someone asked for pix of the final installation. I have updated the stored file:

link http://www.mediafire.com/?t3e8lipn4rgzron

Nickw
_________________
"It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650
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hockeyshifter
Flying Brick Rider


Joined: 01 Jan 2006
Posts: 177
Location: harpers ferry WVa.

PostPosted: Sat Sep 18, 2010 6:53 pm    Post subject: Reply with quote

so many of the cooling issues could be solved with an oil cooler.. these bikes run hot period... cooling the oil would really help lower the internal temps and save the cooling fans..
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fix the problem not the blame ; fix what is messed up ; NO one is to blame.
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nickw
Big Brick Rider


Joined: 12 Aug 2010
Posts: 72
Location: Essex, VT USA

PostPosted: Thu Sep 30, 2010 9:48 am    Post subject: Reply with quote

Update on fan installation and operation;

The rebuild is now complete, having unearthed three major items and repaired same. Fan failure, fuel tank leak and fairing mount breakage.

Ran fan test yesterday, worked as advertised. Road test completed, all indicators running in the normal range.

Now I can get some Fall Foliage miles before snow!

Nick W
_________________
"It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650
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nickw
Big Brick Rider


Joined: 12 Aug 2010
Posts: 72
Location: Essex, VT USA

PostPosted: Mon May 05, 2014 9:03 pm    Post subject: 3 year update Reply with quote

Since i did this modification, I have always thought I should try a 3-core radiator, but one of my rider friends dissuaded me with the common-sense approach: does it overheat? No. Then why do it if you don't have an overheating issue? Hard to argue with, so I've left it pretty much alone.
However, I never completed the manual fan switch and the indicator light that I wanted to in the beginning.
I recently came into a parts bike deal I couldn't pass up and with it came a nice three-core radiator and working OEM fan. I felt that the stars were aligning with a purpose, so i tore it all apart to fit the 3-core with my fan installation.

News Flash; As suspected by others here,the Spal fan I used will NOT work with a 3-core radiator, it moves the fan back far enough to interfere around its entire periphery. I did not trust the OEM unit enough to install it with the new radiator, as it starts hard and takes a bit of time to get up to speed when energized. Indications that the bearings are headed for failure, not something I wanted to repeat.

I did get to play scientist and characterize the OEM fan a bit and weigh and inspect the two radiators side by side:

Fun Facts for Fans and Radiators:
Weight of OEM 2-core radiator: 4 lbs 2 oz
Weight of OEM 3-core radiator: 4 lbs 6.5 oz
fluid volume of 2-core radiator; 750 ml
fluid volume of 3-coreradiator: 900 ml

OEM fan draws 5.25 amperes @ 13.25 V unblocked
same fan draws 7.25 amperes if input is totally blocked (laying flat on a bench)
Current figures were also taken @ 12.63 V and were 4.70 and 6.73 respectively.

Close inspection shows the fin density of the 2-core looks a little higher than the 3-core, this may explain the reasoning behind removing the rearmost row of fins as it would do the least cooling of all three. Two denser rows mat be as efficient with assisted airflow as three under more rigorous testing tan I have equipment for.

Since I am a techno-phreak, I ordered the smaller Spal fan and will build a set of brackets to fit with the 3-core unit. If that ever gets completed, I will provide a report on its success.
_________________
"It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650
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RAL88
Flying Brick Rider


Joined: 28 Apr 2004
Posts: 733
Location: New Mexico Land of Enchantment and 365 days of riding USA

PostPosted: Mon May 05, 2014 10:46 pm    Post subject: Reply with quote

I have a 3 core radiator and a SPAL fan and there is more room behind the fan than there was with the oem fan. From feel I think the spal moves more air and as for noise the SPAL is definitly quieter. The fan I used is a SPAL 6.5" 30100402.
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Rich

"If it ain't broke, take it apart and make it work better"
*************
'96' K1100LT-SE
'97' R850GS-R
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atlantaboblutz@live.com
Big Brick Rider


Joined: 10 Nov 2011
Posts: 60
Location: Atlanta, Georgia

PostPosted: Mon Jun 09, 2014 10:27 am    Post subject: Installed SPAL 6.5 inch Reply with quote

Well, in reading this thread and shuttering at the cost of an OEM fan, I went the SPAL route. Here are some photos....

This was my initial fitting using 1/8" aluminum. the initial cut-outs were for airflow.

the below is the final after adding more cut-outs and needing to shift the position of the fan to the right due to a frame brace which interfered.

and finally, here it is in the bike.

Observations...

1. My bike's fan kicks on a little earlier than most --- at the 3/4 mark on the temp gauge BEFORE the red lines begin.

2. This fan... when forcing it to kick on ... drops the temp to the mid point and holds it there if you keep sitting in one place motionless.

3. Unlike the OEM fan, it does not appear to drop the radiator temp enough to make it cycle, so with the outside temp at 90 degrees ambient and 90% humidity the fan runs and the temp holds. Perhaps it would cycle if I left the bike sit long enough... but I'm impatient and was ready to roll!

With the OEM fan, the temp would drop just a bit more, the fan would shut down, and then the temp raise again to 3/4... triggering the fan.

Even if I purposely added a bit of RPM on my second "force it to run" trial, the temp still held at the mid-point of the temp gauge.

If I lived in the desert S.W. in the U.S. I would probably opt for the 7" fan and suffer through the tighter fit to gain just a bit more cooling capacity. But for my climate, holding at the mid-point on a hot and humid day works well.
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Bob
Atlanta GA

'94 K1100 LT
'76 R75/6
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Flying Duck
PsyKotic Waterfowl


Joined: 27 Jan 2005
Posts: 9945
Location: Bumf***, WA

PostPosted: Thu Jun 19, 2014 3:24 am    Post subject: Reply with quote

I opted for a simpler approach. Since I don't have a 3/4" drill bit for metal, I just cut the rubber bushing at the top in half and put the bracket in between the two halves.


_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE
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atlantaboblutz@live.com
Big Brick Rider


Joined: 10 Nov 2011
Posts: 60
Location: Atlanta, Georgia

PostPosted: Thu Jun 19, 2014 7:25 am    Post subject: Reply with quote

in retrospect...

although the 6 1/2 inch works.... the fan really doesn't need a ton of support. It's not a jet engine after all! So a recommendation to anyone who cares to hear from an admitted amateur shade tree wrench turner....

Go with the 7" fan and a more straightforward bracket approach as shown above. Take advantage of the bit more air flow it provides. Skip over-engineering the bracket as I did.

With summer temps now in full force in ATL... in heavy traffic ... the 6 1/2 continues to keep the temp from anything higher than a bit over the halfway point... but more cooling is always better.

In any case... it avoids the WAY HIGH cost of the BMW/Bosch fan motor for a really simple task that all water cooled engines share.
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Bob
Atlanta GA

'94 K1100 LT
'76 R75/6
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Flying Duck
PsyKotic Waterfowl


Joined: 27 Jan 2005
Posts: 9945
Location: Bumf***, WA

PostPosted: Thu Jun 19, 2014 8:08 am    Post subject: Reply with quote

Here's a 7" slim fan I just found on FleaBay for $23.50 shipped. Claims pull CFM is 1200-1450. Not sure if I believe that but the blades look bigger than on the SPAL fans.

http://www.ebay.com/itm/231025894298
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE
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abreeze
Flying Brick Rider


Joined: 17 Jun 2006
Posts: 671
Location: atlanta

PostPosted: Thu Jun 19, 2014 4:43 pm    Post subject: Reply with quote

Cool mod,

Another option is to just buy the motor from beemerboneyard.com its about 80$..

http://www.beemerboneyard.com/kfanmtr0427.html

The new motor also has ball bearings, so i would guess they would last longer...
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RAL88
Flying Brick Rider


Joined: 28 Apr 2004
Posts: 733
Location: New Mexico Land of Enchantment and 365 days of riding USA

PostPosted: Thu Jun 19, 2014 8:47 pm    Post subject: Reply with quote

Hey Drake,

Just looked at your link and it said $223.50 for the fan.

Flying Duck wrote:
Here's a 7" slim fan I just found on FleaBay for $23.50 shipped. Claims pull CFM is 1200-1450. Not sure if I believe that but the blades look bigger than on the SPAL fans.

http://www.ebay.com/itm/231025894298

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Rich

"If it ain't broke, take it apart and make it work better"
*************
'96' K1100LT-SE
'97' R850GS-R
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