A good buddy of mine recently gave my a couple of S40 DX transmissions with instructions to make one of out two for his DD we're auto to manual swapping in the near future. So I figured I'd do a teardown/rebuild thread since most or all of them lack pictures now. The first transmission I pulled apart was awesomely destroyed to such a degree that I figured I'd make a separate thread showing some common (and not so common) failures and what they mean. Bad for my buddy, but good for H-T. Now, on to the carnage!



Awesomely destroyed final drive. I have no idea what this thing came out of or exactly what happened here, but it looks an awful lot like wheel hop to me. Oddly the ring gear on the diff came out unscathed.



Messed up 1st/2nd sleeve, 2nd gear side. Note how the teeth are rounded over. This will grind!



Chewed up 1st/2nd hub. I can't say I've ever seen one messed up like this on a D-series trans before. I'm still not sure exactly what happened but it's pretty apparent that it was abused pretty severely.



Rounded over engagement teeth on second gear. Well past what would be considered reusable. Again this will grind!



Flattened out 2nd gear synchro spring



^ It should look like this.



2nd gear synchro, which is actually fine. The teeth are worn a bit, but it's still got lots of clearance and the only part of second you could realistically reuse. So much for "it must be the synchros!"



2nd gear synchro, note the burs on the teeth, this can be fixed with a flat file.



Completely worn out 3rd/4th shift fork (bottom) note the good 5th gear fork (top)



Another pic illustrating the extreme wear on the 3rd/4th shift fork as well as the 3rd/4th sleeve. If you look closely you'll notice the flattened out 3rd gear synchro spring as well.

I hope this helps someone out. I will update it with more pics when I find some more broken stuff.

 

Another blown final drive from tranny I took apart a couple of years ago. Customer said it was "clicking" If you look closely you can see where the countershaft bearing walked out as well, super common on Y8 trannys and it will cause 2nd gear to pop out.

 

Nice pics!

1. The engagement teeth on the gear are truly awful! LOL
2. Some synchro springs from Honda are square like the one pictured. That's not because it was round and flattened out. It's been abused by worn sleeve teeth though.
3. The final drive breaking teeth on one end like that (rather than pulling ALL of the tooth off on each tooth from bending fatigue) can be from shaft misalignment (overly worn bearings, excessive countershaft runout, excessive ring gear/differential runout)

 

Thanks man

Those are about the worst I've ever seen on a D-series. I have seen a K-series 6 speed tranny where all the engagement teeth on second gear were completely sheared off though.

I've never seen square ones before, at least where they were supposed to be square.

I never checked with a dial indicator or anything, but I did spin the diff and I didn't get visable OBX like runout. Diff bearing felt really good as did all the bearings (except the ISB, and even that wasn't all that bad, felt a little rough, but the cage was still intact) No CSB walkout either.

I really don't know what the story on the trans was, it and the other one were both freebies. I've taken apart a lot of D-series trannys before, but I've seen one that was so screwed up in so many ways. Originally there was supposed to be 4 trannys, one of which was attached to an engine someone was trying to blow by ramming it in 1st at around 70mph. I'm kinda thinking this might be the one.

 

I was just saying it CAN be from misalignment. Not that it 100% was. It's so hard to determine the exact cause sometimes, especially when so many final drive failures do come from shock loads associated to wheel hop.

Just something else to consider when the teeth are all broken on just one end like that. In contrast, look at the other countershaft you've posted. The breaks are all over that poor bastard. Hahah!

 

Great stuff!
Thanks a lot!

 

find or grind them!

 

Nice thread..now could high vs low rpm gear changes be affected by problems like those teeth?

 

I know this is old as hell, but if someone else is looking at this, yes they can.

 

And now for S20 carnage pics. This thing was run no or very little fluid for quite some time. It was popping out 5th for a while. With fluid it in it surprisingly enough it worked alright other than an absolutely nasty 4th gear grind and the occasional 2nd gear grind.

Broken 1st/2nd shift fork:




This was a 4th gear snychro spring at some point. I never did find the rest of it:



This is why I always say make sure you take everything apart when do an ISB replacement. That's an oil passage all plugged up. Not sure if pieces of synchro spring, or pieces of shift fork:




Leave it the way it is and you will starve bearings for oil.

Blue gears!:




No you're not supposed to be able to mark gears with a file:



Clearance?! What clearance?!



Badly worn and pitted 1st and 2nd mainshaft gears:




Countershaft with gears still attached, note the blue 4th and 5th gears here as well:

 

wow! that poor trans must have been beaten on harrrrrrrrrrrrrrrrrrrrrrrrrrrrrrd. i pulled apart an old ef si transmission that had a blown diff before, all internals were bright metallic blue from a leaking axle seal and being smashed on bone dry. stanky!!