400ex forum

mrw105 · #1 10-09-2011, 02:10 AM

hey guys. ive owned a 2000 honda 400ex that i traded for a few weeks ago. long story short i got screwed over. i shouldnt have bought it when i saw the previous owner start it with a screwdriver, but i saw potential lol. anyway i got all the electrical problems fixed, got it running (thats another problem but not worried about it atm) and i found out that 3rd gear slips. its there and you can shift into it but once you get past 1/4 throttle it slips and makes a faint chatter(i wouldnt really call it a grind) i called my local honda shop and they said my clutch plates are sticking (i think its the gear or a bent shift fork) what would you guys think it is? it shifts and runs fine in every other gear. also, i bought some new break pads for the puppy. i installed the pads in both front calipers. when to put them back on the bike and the outer pads are so tight against the front hubs wont even spin. i know all new pads somewhat drag on old rotors but these are completely holding the rotor from spinning. i tried to adjust the brake stay but the one bolt is stripped on the left caliper, and the right one is siezed. i dont feel like shelling out buku bucks trying to fix this thing, im already a quad, dirt bike, and 700 bucks worth of parts drowned into this thing. it runs and handles amazingly well but its hard to ride with no 3rd gear or brakes lol. can someone lead me in a direction to how to fix these problems? thanks for all the help.

Here 2 help · #2 10-09-2011, 04:13 AM

The third gear problem is simple and expensive. Typically it will require replacing 2 gears and a shift fork (the shift fork becomes damaged after the gears are damaged). In an extreme case, the shift drum needs to be replaced also.

The brake problem is most likely frozen slide pins. The pins allow the caliper to move side to side as the brake operates.

mrw105 · #3 10-12-2011, 12:41 AM

i split the cases tonight and by surprise the gears actually look okay. theres no teeth missing on any of them and they actually look brand new still. im really confused on this one. the forks seem fine, theres 2 larger outers and one smaller one in the middle. the drum looks okay as well but then again i cannot tell how when the drum or forks look bad (need advise on that lol). i know the clutch plates are pretty bad, but if it was only the clutch problem it would slip in all gears. i took some pictures of the drum,gears, etc. in case someone needs to see them to help me out. my local stealership wanted 700 to just split cases and i said f you guys and did it myself. the calipers im not worried about ill get used ones off of ebay. i just wanna get this 3rd gear problem resolved first.

Here 2 help · #4 10-12-2011, 01:38 PM

The problem with jumping out of gear has nothing to do with teeth missing. There is a total of 10 gears in a 5 speed constant mesh gearbox.

The mainshaft (input - the one the clutch fits to) has low gear cut directly onto the shaft. The gear next to low is 4th, then 3rd, then 5th and then second.

Some of the gears are splined to the shaft and the others spin freely. On the output shaft, the gears that are splined or free spinning are just the opposite of the input shaft. i.e. 1st gear on the input shaft is cut into the shaft, but the gear it engages on the output shaft spins freely. Also, low gear on the input shaft is the smallest, but low gear on the output shaft is the largest.

A gear is selected by sliding a splined gear into a free spinning gear effectly locking the free spinning gear an making that gear drive a splined gear on the opposing shaft, or converesly, locking a free spinning gear on the output shaft which engages a splined gear on the input shaft selects that gear.

1st, 2nd and 3rd gear are splined to the input shaft while 4th and 5th gear are splined to the output shaft.

The input shaft only has one slider and one shift fork which selects 4th and 5th gear. The output shaft has two sliders. The RH shift fork selects 1st and 3rd and the LH fork selects 2nd. Here's the tricky part - third gear is selected by sliding 4th gear (splined) on the output shaft into third gear (free spinning) on the output shaft which engages 3rd gear (splined) on the input shaft.

Keep in mind, the engagement dogs do not engage 100% of their depth. Usually no more than 50% is typical. For your problem, inspect the engagement dogs on 4th gear (second from the right on the output shaft) and the mating dogs on third gear (third from the right on the output shaft) and the RH shift fork. Of course, also look for damage to the snaprings and thrust washers associated with the parts. When I work on a transmission, I replace all the snaprings and thrust washers associated with the damaged parts just as a matter of precaution.

In a severely damaged transmission, the groove that moves the shift fork can be damaged at the point where the fork is holding the gear in.

Without seeing the parts, I would replace third (Honda part # 23471-HN1-000) and fourth (Honda part # 23451-HN1-000) gear on the output shaft and the associated shift fork (Honda part # 24211-KCY-670).

Most transmission problems can be avoided by learning how to shift properly. Most people pull in the clutch lever, stab the shift lever and let off the clutch. THIS IS WRONG. You should pull in the clutch, operate the shift lever and hold it, engage the clutch and then let off the shift lever. It takes practice, but I have been riding and racing for over 20 and have never had a transmission problem yet. BTW, I only use the clutch for starting, stopping and "feeding" power to the rear wheel. I use the throttle for shifting. It is a technique that has to be practiced, but it will reduce the probability of damage to the clutch and transmission.

Good luck, hope this helps.

mrw105 · #5 10-17-2011, 01:59 AM

wow man i you really know your transmissions! now i understand how they work much better. i took some pictures of the parts hoping this would help in defining this issue. hopefully this helps. if i need to take more pictures let me know.

Here 2 help · #6 10-17-2011, 02:21 AM

First - post a pic of each side of each shift fork.

I battled a transmission in a V65 magna and finally figured out that the factory had installed a shim on the wrong side of a gear, but the condition of the shift fork thrust sides help tell the story.

mrw105 · #7 10-18-2011, 12:27 AM

well here they are. i know the one outer fork looks like has some rub on it. you can see it from the pics.

Here 2 help · #8 10-18-2011, 04:14 AM

Yes, right shift fork is marked with some "rub" caused by the pressure of the gears trying to push apart indicating that the gear the fork is engaged to needs to be replaced an well as the mating gear.

Get the three parts I gave you the part numbers for (and any damaged shims and snaprings), install them, assemble your engine and all should be well.

mrw105 · #9 10-25-2011, 01:28 PM

so i should replace that damaged shift fork, the gear that it moves, and all the snap rings/ shims from that gear?

Here 2 help · #10 10-25-2011, 06:31 PM

Click on this link World of Powersports' 2000 Honda ATV TRX400EX Parts List

I can't tell from your photos exactly what is causing your problem, but if it jumps in 3rd as you describe, then you need to replace parts KEY numbers: 8, 10, 12, 23, 27 and 28, plus the shift fork #1 on this link World of Powersports' 2000 Honda ATV TRX400EX Parts List

If there is no other damage (only a detailed visual examination of the parts would reveal), then replacing these parts should fix it.