NB Floyd 37 Posted April 14 Went riding yesterday. Pretty quickly I found out that four wheel drive was not engaging. 4x4 light came on. ( and off when switched to 2wd) No unusual noises. The electrical connector felt tight at the top of the front diff. Any thing to check for ? Any common issues? thanks NB Floyd 2004 450 ES Share this post Link to post Share on other sites
AKATV 839 Posted April 14 (edited) Usually with your model (02 and up with selectable 2WD/4WD) ,if there is a 4x4 fault, the 4WD light will flash a few times as a code, indicating a fault area usually, it flashes 2 to 6 times Is it flashing at all? Edited April 14 by AKATV Share this post Link to post Share on other sites
shadetree 5,969 Posted April 14 most times when this happens, one of the speed sensors goes bad on the front diff. there are two of them on the front diff, one is right where the front drive shaft enters the front diff, and the other is located in the front, top side of the diff. if this is not the issue ?, then the 4wd unit ( control unit ) is bad. Share this post Link to post Share on other sites
NB Floyd 37 Posted April 15 Took a quick look at the bike this morning. The 4x4 light did not flash with engine off and key on. Did not try with it running. I saw the speed sensor on top of the diff , and a elec connection at the drive shaft input. The wire at the drive shaft input was pulled out of place and under strain , I routed it back under the shield. Hopefully that helps. is there a 4x4 actuator in / on the front diff , is that what the 4x4 switch controls ? thanks ! NBF Share this post Link to post Share on other sites
spock 44 Posted April 15 First thing I'd do is check the condition of the splines on the front prop shaft - the ones near the front of the engine can get stripped, common problem on those older Honda's. 1 Share this post Link to post Share on other sites
jeepwm69 7,719 Posted April 15 Yep, if throwing no blinking codes I'd check the spines on front driveshaft and coupler. I've had to replace a few. Share this post Link to post Share on other sites
shadetree 5,969 Posted April 16 On 4/15/2024 at 9:43 AM, NB Floyd said: Took a quick look at the bike this morning. The 4x4 light did not flash with engine off and key on. Did not try with it running. I saw the speed sensor on top of the diff , and a elec connection at the drive shaft input. The wire at the drive shaft input was pulled out of place and under strain , I routed it back under the shield. Hopefully that helps. is there a 4x4 actuator in / on the front diff , is that what the 4x4 switch controls ? thanks ! NBF yes, the sensor where you adjusted the connection, that is where the speed sensor is. as stated, be sure to check the pinion collar splines for being stripped ?. Share this post Link to post Share on other sites
NB Floyd 37 Posted April 18 I put the bike on a stand to check 4x4. it seems like the propellor shaft has stripped splines at the motor. when 4x4 switch is activated the out put shaft turns but front wheels do not engage. I could actually hold the shaft still and hear a noise in the coupling at the front of the motor. good news is that the front diff spins the shaft with no slip when I turn the wheels by hand in 4x4. what is the replacement propeller shaft called ? I understand you need to unbolt the front diff to move it forward. Are there any fasteners on the propeller shaft ? Any other tips to make this a smooth replacement? Thank you. Nbf. Share this post Link to post Share on other sites
jeepwm69 7,719 Posted April 18 You'll undo a bolt on the bottom of the front diff (14MM), a bolt and spacer on top of the diff (I think 14mm on nut/bolt) and the mount on the front of the diff. I remove the metal bracket on the front, or at least unbolt it, and loosen the bolt so you can swivel it out of the way. That's it. Pull the front diff forward. The prop shaft will then just slide out. Check and see if you need the prop shaft or the coupler, or both. Also check the splines on the shaft coming out of the engine. They should be square cut, not pointed. If they're pointed (shark toothed) they're worn out. Used Shaft https://www.ebay.com/itm/296213716938?epid=1911839859&itmmeta=01HVRVTQP5BSREC4RFXBMWHXNG&hash=item44f7b69fca%3Ag%3AA7MAAOSw9cRlxUff&itmprp=enc%3AAQAJAAAA8HJls4L8zrcD5BV69nyIFrpoNL4tguslMY9%2FXJBfvkAgiUjPZtgcCS%2ForBApuqsc%2FBFlBlCf0pzHMTAwMcoEBj6n3PkpDrg%2Fca9DB%2FOJ--3eGB%2Bz%2FdoDysjhrTzXWjxX2GfX%2BkoNj5r9WQQewOnV29CxZL%2FG7Z2vL%2FcYHWyb69QzRsULM4aqgwzJwzPzmkYmssvVhrXztzrjyXZv%2B3mXpBLWHUEw7yTLEUQL1CKBVh7ipWluy5w95VCYdFWCFxVV0I2HRA2X%2F2ZAeetS29FF48w0wyPQd0KAvW%2FqwHN0wQXOXukFt7B9UspDeyg%2BwZWpSQ%3D%3D|tkp%3ABk9SR5L76pveYw&LH_ItemCondition=4 Used Coupler https://www.powersportsnation.com/honda-rubicon-500-fa-02-front-drive-shaft-engine-coupler-40402-hn2-000-44196.html If you want new, part number for complete shaft and coupler is 40400-HN0-670 and it's about $200. https://www.motosport.com/oem-parts/part-number/40400-HN0-670?mmy=honda%3Btrx450 foreman 4x4 es%3B2004&group=front-final-gear&qty=1 Those are the cheapest used parts I could find, and the cheapest new shaft I could find. Note that you need 02-04 only. The earlier 450's were full time 4wd so the shaft is different. Share this post Link to post Share on other sites
NB Floyd 37 Posted May 16 Ordered the Motorsport part. I miss having 4x4 ! I may have some questions when I do the install. 1 Share this post Link to post Share on other sites
NB Floyd 37 Posted May 22 Got the part. I have removed bolts from front diff and I can pull it forward. When I pull diff forward the coupler does not quite clear. I have sprayed down the coupler with penetrating oil. any other tricks to make it come out ? Does the coupler on the engine side also come out ? The new shaft came with one. thank you nbf. Share this post Link to post Share on other sites
jeepwm69 7,719 Posted May 22 Coupler on the engine side has a spring up in it. Pry the coupler forward, away from the engine. Should be able to clear it then. Share this post Link to post Share on other sites
NB Floyd 37 Posted May 24 update. Front propellor shaft has been installed and 4x4 is working again. the coupler at the engine was jammed with mud. I pulled and pushed diff back / forth and eventually got it loose enough to clear. the front spline was pretty stuck but with some pb blaster and “jiggling “ it came out. the spline on shaft at the motor end was totally stripped. everything went back together good with light greasing , but clearances are tight. Big thanks to Jeepwm69 for pointing out the right part. Not an easy job for me , thanks to the forum for all the great advice to make it a success. nbf. 1 Share this post Link to post Share on other sites
jeepwm69 7,719 Posted May 24 Glad you got it fixed, and thanks for reporting what you did. That will hopefully help others in the future when they're searching for answers. Share this post Link to post Share on other sites