Mazda Tranny, lost 4th

[Kansasipi]

Darnedest thing, one day it was fine(the tranny) I start up the road shifting thru the gears and when I got to 4th, notta, od was fine so being on the hwy I continued.

Every gear works fine even rev but 4th just makes a spinning noise.

I'm gonna tear into it this afternoon as soon as I get garage space, I am hoping to find a lock ring loose or bad sync.

But if AllanD has a suggestion I sure would like to hear it,thanx in advance...

Mo

btw since I lost my original ID here due to change of email my truck is an 85' 4x4 w/4.0, manual tcase, hurst shifter on the mazda tranny

 

[Kansasipi]

update

Here is what I now know....

The manual Mazda tranny had proper amount of atf with very little discoloration.

There were several small chunks of metal chewed up and some scarring at the forward end of the trans hsg around the input shaft bearing, and the bearing cage was exposed almost 1/4 inch with the cage showing damage as though it had spun in the bearing cavity.

I saw no damaged gears or syncs, in fact I believe that I was engaging 4th gear by hand with the cover off by pushing it rearward more than the shift forks would have allowed.

I cannot tell what souce the chunks of metal came from but I am not sure I should be able to see as much of the input shaft bearing as I am seeing.

I am not a tranny guy and I am not rich enough to throw money at a problem until it goes away but I am baffled by the lack of damage with the known malfunction.

Any help even a swag would be much appreciated right about now....

 

[Kansasipi]

I Maybe on The Right Track..Maybe

OK, just got some info from a part supplier that thinks he knows what the problem is. I am gonna paste his answer here to see if I can get any info, since I havn't had any yet, on his take of my problem.

I pretty much asked him what I had posted here and this was his response....

"If you only lost 4th gear and everything else was working reassonably. The problem is most likely a problem wth the input shaft. I would expext to find the cone broken off. This part is included in my kit. Check that,and let me know. Pat"

I have been coming here to trs for almost ten years, trs is the reason I have solved every problem I have ever had with my little ranger and I value the opinions I have heard here.

So I will ask if Pat has the right Idea and first thing in the morning I am going to disect that tranny but I have no idea what he means by cone unless it is referring to the outer race of the input shaft bearing that does not show up on my pdf.
So what is he referring to?

 

[MAKG]

If, by the "cone" he means the synchronizer cone (and not the bearing), he may be right.

But if THAT broke off, you have to ask why. Were you powershifting? If you weren't abusing the transmission, it probably has another failure you just haven't found yet.

First question: Were the chunks steel or aluminum or something else?

I really think you would be better off with a good junkyard transmission.

 

[Kansasipi]

Conehead

I don't have too many junkyards to choose from and the 4x4 stuff is scarce, if it looks that bad a rebuilt one is going for around $500.

Heck I had this one rebuilt 4 yrs ago and it cost me $1400, and the guy didn't even offer any KY jelly....

So, what part is the cone? and how far down the main shaft is it, I am already removing the OD stuff to get to the plate.

And to answer your question I havn't even been driving over 55 mph just to save gas, so abuse is not the cause. But I am looking at every angle and the malled metal I think was steel but we are talking BB size pieces and so far I have seen only a cpl. But like I said I am just getting started on disassembly.

BTW thanks for any advice you can offer me trannys are greek to me, I fixed the bearings in my Dads Nissan and that is my only experience inside one.

Mo

 

[Kansasipi]

Tranny Shop Is Open for Business

I've been repairing some sort of equipment for over 40 years and in every single repair I have ever made I have this moment when I get to the root of the problem that gives me the same 'high' I used to get when I would run 10k's.

The 'cone' has in fact broke away from the input shaft, but it is why and how it lasted so long that satisfies me the most.

If you have read my previous post the rebuild I paid so dearly for is the cause of my tranny failure, BUT if it were not for my diligent changing of the mercon, sometimes twice a year, this would have happened long ago.

The source of my metal frags were steel, it was the steel cage around the input shaft bearing (which is a cone type bearing). The person who did the work misjudged the amount of shims needed under the plate. He didn't miss it by much, just enough to heat the input shaft and sync cone regularly enough to fatigue the shaft until it severed at the cone.

I can see the result of overheating and discoloring of several bearings that still run smooth but are very dark grey.

I put a lot of miles on this truck as i have had it for ten years. It's been from Atlanta Ga. to Vermont twice and 4-5 times from Atlanta to here in N Central Ks before I used it to pull a trailer full of my stuff when I moved here permanantly 3 yrs ago.

That is one damn good tranny and all I have to say is I got more than my moneys worth out of it and I get to rail on the fancy dan jack ass who was the cause of my woes from this day forward...priceless.

Now I just need $250 to ythe kit to fix it, until I tear up the next one...

 

[MAKG]

Bad setup....oops. I wonder if the depth mic was at the cleaners that day....

It sure sounds like you nailed it.

 

[Kansasipi]

Yep

I found a good kit with input shaft/gears+clustershaft/Gears+bearings/gaskets for $260. The two retaining nuts off the mainshaft+countershaft are extra but well worth the changing and I am going to change the slave and prolly the disc as long as I am in there...

I like my truck, would not trade for notta.

It has never let me down as long as I have done the werk.....

 

[Bill G]

Take a look at these folks here for parts. I have had good experiences with them.
http://stores.ebay.com/Southwest-Gear

 

[AllanD]

The "cone" (and the "dog teeth") are welded to the rest of the gear and
severe shock loading can snap them off.

I've never seen it done on 4th gear.
I have twice seen it done on 3rd.

But if that indeed happened the effects would be exactly as described.

a Real "Zebra" of a problem IMO

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