Topic: Transmission locked up? - WHY? BECAUSE I BOUGHT CHEAP SEALS

[tsflstb]

Last night on the way to a local bike night, I was cruising along in 6th gear at 60 mph.  Without any warning, the rear wheel locked up.  I skidded to a halt on the side of the road.  After some rocking back and forth, I finally got the bike to move in gear with the clutch pulled in.

Here's the current situation:
- I can't find neutral with the shifter.
- The bike will roll in gears 2-6 with the clutch pulled in.  It will not move in 1st even with the clutch pulled in.
- I didn't hear any strange noises before the incident.  The only thing wrong was the clutch was slipping under a big load.  I was planning to change it soon, so I've just been babying the bike lately.
- I've got a bag bald spot on the rear tire.
- I need to wash my drawers.

Anybody had something like this happen before?  Any ideas?  The bike was running great before this (don't they always).  I'm not looking forward to splitting the cases.  I may pull the clutch cover off later today to see if there's anything wrong in there.

[puppytrax]

That is a known issue with your year and model...   

...[coff, coff]...

[tsflstb]

'75 400F -- but I thought transmission woes transcended all models, creeds, religions...

[Boomologist]

Good thing that happened on the straight and not in a tight curve! Glad you're alright. Shorts can be replaced.
Does the clutch pull feel different now?

[puppytrax]

'75 400F -- but I thought transmission woes transcended all models, creeds, religions...

I can't speak for other Honda models...(I wasn't even aware the 400 had a 6-speed box) but my brand-new 1972 CB500 [bought in 1972] would lock up its gearbox during the 1-2 shift [twice] and the 2-3 shift [once]...like you said, skid (or pull in clutch) and after stopping, rock it to free the gears...

Supposedly this was a known issue for the early CB500's...my dealer refused to work on it, so I sold it with about 500 miles on it...but I believe I've read since then that the drum (?) and selector forks (?) were changed to try to fix this problem...on the CB500...

[Tim2005]

Hmmm, that doesn't sound good. I'd pull the sump off (drain the oil into a clean container first) and get a flashlight & have a look at the gears - 400Fs do occasionally destroy the 6th gear on the layshaft, maybe the remains of one of the teeth flew somewhere and locked it all up. You might find some of it in the oil too (hence the clean container). The only other major gearbox failure I have ever heard of on a 400F was a bearing seizure, very odd indeed, but that wouldn't turn at all afterwards.

Oh, if there's nothing appearing wrong and no metal in the oil I'd be tempted to pull the back wheel and make sure it isn't something strange happened inside the rear brake drum.

good luck! keep us posted

[GroovieGhoulie]

The 400F had a whole different box than the 500, which was known for it's transmission issues.  I was not aware of any 400F transmission issues and I await the outcome of this with baited breath.

I do think cracking into that motor is what's going to need to be done.  You can go in from the bottom so you don't need to disassemble the whole top end, just the bottom end.

[TwoTired]

- I can't find neutral with the shifter.
- The bike will roll in gears 2-6 with the clutch pulled in.  It will not move in 1st even with the clutch pulled in.

Anybody had something like this happen before?  Any ideas?  The bike was running great before this (don't they always).  I'm not looking forward to splitting the cases.  I may pull the clutch cover off later today to see if there's anything wrong in there.

You are getting multiple gears engaged at once except when 2 or 6 are selected (which are likely ones engaged all the time).
Shift drum and shift forks are suspected cause.  However, other trans issues may have occured after the initial fault, as lockup at speed is pretty stressfull on the internals.  I wouldn't trust it again without spliting the cases.

bummer,

[tsflstb]

Two Tired -- I meant to say it will roll with the clutch in any gear BUT 1st.  I doubt that will change your diagnosis much.

Crap, not what I wanted to hear.  I'm afraid it's going to be out of commission for a while until I can clone myself.  I won't have time to dedicate to a full tear down for a few months.  Kind of takes the wind out of my sails after getting it back on the road.  I agree I'd never really trust it until I can get in there and see what's going on.

On the plus side, I was VERY lucky to be on a straight section of road and to be riding with a good group to help me out.  I'll get it fixed eventually.

Loaded up for the ride of shame.

[bryanj]

People keep telling me the 500 has box problems but in 30 years i only seen 2.
(1) exploded a 2nd gear into pieces---on a race day
(2) Started "jumping" gears----owner admitted to neglecting to use clutch!

Now the clutches regularly slipped under load but never seemed to wear out and could be cured using 450 plates, and neglected oil changes siezed the cams requiring  a "new" head but apart from that they were taken down far less than the 750's

[puppytrax]

People keep telling me the 500 has box problems but in 30 years i only seen 2.

I had not known there was an issue either. When my CB500 [this was in 1972] gearbox locked up the 3rd time, I took it to the dealer, Honda Village in Niagara Falls, NY. The salesman I bought it from, "Whitey", said that the 71's had had a problem with the gearbox but that the 72's (which he had sold me) had the upgraded internals and my problem wasn't covered under their "recall". IIRC, it was just a technical service bulletin, and detailed replacing "the shift drum and sliding forks" (my memory on this may be off a bit) under warranty.

I was really pissed that they wouldn't fix it (less than 500 miles) and soon sold it and bought a Triumph. But after about a year, I got a letter from a lawyer representing a class-action lawsuit against American Honda Motor Co for selling left-over [unsold] 1971 motorcycles as 1972 models. AHMC was issuing dealers new Manufacturers Statement of Origin documents and the dealers were selling the bikes as brand new model year 72's. My VIN was in the list of affected cycles. (The rest is a whole separate story, worthy of a magazine article - AHMC eventually settled out of court, after  news  exposure).

But as it turned out, my bike was indeed a leftover 71 sold to me as a 72...with the un-upgraded gearbox...The dealership went out of business soon after; the salesman died (so my friends told me); and I eventually received a settlement check from AHMC for the difference between the sale value of a 71 and a 72...

Go figure...

But I had seen the CB500's in a showroom on Okinawa in 71 (I was stationed there a year), especially the candy-apple brown ones, and that's what I wanted...

Really turned me off on Honda, though...especially AHMC...

/rant 

[bryanj]

Bad story, as i said in my personal reply, anything that can go wrong will somewhere sometime. There was a recall on the gear detent mechanism and clutch, which i have a bulletin for, but it is difficult to comment on the VERY early 500's as, officially, only the 72 K1 was ever imported to the UK, in fact Honda produced the K1 and the K2 simultaneously and the 500 K1 Along with the 550 K1 and K2 at the same time. Here in UK we only ever had the 500K1 the 550F and the 550K3

[tsflstb]

Thought I'd reply here in case anyone was interested.  After thinking about just selling the bike, I reluctantly farmed out the engine repair because I just don't have the time to mess with it.  The mechanic is a top notch guy and a local racer that knows his way around all types of bikes.  www.metricmotorcycles.com

He split the cases and discovered that 2nd gear had seized to the output shaft.  I guess 2nd gear is supposed to be a freewheeling gear that is engaged to the shaft all the time.  The lock up happened when I was in 6th gear.  Anyway, it looks like it lost lubrication somehow, heated up and is now "stuck like Chuck" as he says.  They're still digging into it looking for the root cause.

Never heard of this type of problem before...could it be the oil pump gave up?  Is the tranny the first thing to be lubed out of the pump? 

Just thought I'd give everyone something else to worry about.

[Boomologist]

If the case is split I would remove the rod & main caps to check for damage such as you would see from a bad oil pump. I have never heard of a gear sticking to the shaft. Even if it didn't get enough oil from the pump it should get enough just from splash.

[tsflstb]

Ok, I think we've figured out the cause of my sudden transmission lock up.  Like I said before, the 2nd gear that is supposed to freewheel on the output shaft had seized to the shaft.  Things got pretty hot and just welded themselves together.  Couldn't separate the two with a 10 ton shop press:



Anyway, I was pretty concerned when #$%* like this happens.  We tore the engine completely apart, and everything else looks great.  Oil pump works like a champ.  So I thought it was just a freak thing and was ordering the parts to put it back together.  I'd done the engine a couple of years ago and had ordered a cheap seal kit from cycle-recycle.com.  I ordered the same kit again this time.  When my mechanic was about to install the new seal on the output shaft, he noticed that it has an oil passage that is supposed to lube the output shaft.  The holes in the cheap seal set were not manufactured correctly and didn't let much if any oil to the bearings in the output shaft.  I spent the extra $20 for a genuine Honda set of seals, and sure enough you can tell the difference. 

Honda seal on the left, cheap ass POS seal on the right.


I'm pretty sure this was the cause and would urge everybody to learn from my cheap ass and buy genuine parts when you can.  I've emailed the place I bought them from and let them know about the problem.  No response yet, but I would hope they realize the severity of the situation.  Having a rear tire lock up at freeway speeds is not a good thing.  I was a lucky SOB, but the next guy might not be.

Anyway, the $20 I saved has turned into several hundred in parts and labor plus two months of downtime.  I'll hopefully get the engine back next week and get back on the road.

[jevfro]

WOw, Thanks for the update.. I have purchased from CRC and might have bought some bad seals if I didn't see this.  I'd like to know if they respond..
Thanks and good luck/sorry this happened to you/glad you're around to tell the story!!!

[hummbug]

I had a similar incident recently but it was the kickstart lever that spun around and jammed my rear brake on. I'm now left with a similarly jammed gearbox. I haven't replaced any seals but I did replace o rings on my oil pump about 3 weeks prior to it happening. Maybe a similar cause in terms of not enough oil making it to the box? Doesn't the gearbox sit in oil though?  You say you ended up getting this fixed - can you tell me a ballpark figure for your repairs?