This one is long but there is a story and background that, after doing a simple write-up and posting a few pictures, I thought was worth telling.
Just a couple of weeks ago I tore down a core that was returned by a customer. As usual, I won't name the individual but if they want to identify themselves they are welcome to.
This one is interesting on a couple of levels. Many of the units I build are units that were previously rebuilt and had some kind of issue and this one falls into that category. In this case the unit was rebuilt by and purchased from a reputable company. I will not identify that company for a simple reason. That company relied on an employee to do the work and that employee was responsible for his work. Certainly the business is ultimately responsible but I am sure that if the management had known about the deficiencies they would have taken corrective measures. I will give the company the benefit of the doubt. Sadly, that doesn't change the results I found.
This particular unit is an example of a nearly worst case scenario when making a major purchase on something that you cannot easily verify the quality of the product you are buying. Since you can't see inside the transmission or otherwise verify was parts were replaced, the quality of those parts and the skill of the technician, you have to take it on faith that you are getting what you are expecting. A reputable company is typically your best option in these cases. But nobody is perfect and that's what happened here. This is also why when I talk to somebody about rebuilding their X1/9 transmission and they tell me that they found a local shop that said they can do it cheaper, I cringe. Not because I think they'll be cheated, its because my experience is that even the most experienced and reputable shops struggle with these transmissions.
Now for the sake of honesty, I am the first to say nobody is perfect, and that specifically includes me. Nor is that fact likely to change any time soon. In fact, I shipped a unit this week that, as I was preparing to box it up Sunday, I had a nagging thought that I might have not installed the O-ring on the axle seal carrier. That seal carrier in on/off the case several times in the process of shimming the differential. During this process the o-ring is not fitted because it will interfere with the measurement. So did I remember to fit it on the final assembly? I can't be sure and I can't afford to assume and ship a unit that will ultimately have a massive oil leak. So, after removing the stub axle I was removing the four bolts that hold the seal carrier when I dropped one of the washers into the open hole and into the differential. Obviously, I can't leave the washer in the transmission so after failing at trying to fish it out with a magnet I ended up having to tear the unit back down to retrieve the washer. Oh, and in fact, I had left the O-ring off. I have on two other occasions pulled that seal carrier to check for the o-ring but this was the first time I found it missing.
So, on with the unit at hand. As was told to me by my customer, he purchased a rebuilt transmission from a US vendor several years ago. The unit worked initially then locked up. The vendor sent a replacement unit and that is the unit that was returned to me as a core. The customer's complaint was that 2nd gear was grinding badly and there was a substantial leak.
I tore the unit down and immediately found three significant problems. All three were a direct result of the choices made by the technician rebuilding the transmission. One of the things that will ruin a transmission is internal rust. We all have seen examples of cars that have been left sitting, or abandoned, for extended periods of time for whatever reason, until someone either decide to salvage the car for parts or restore it. We all know what happens when water gets into an engine. The cylinder walls rust and pit, rendering the bores unusable. In some cases the bores might clean up with a rebore or they can be sleeved. Transmissions are not so lucky. They tend to accumulate water from condensation. And a transmission, either in a car or not, left exposed to the elements, will accumulate enough condensation to rust the internal parts. Unfortunately, gears cannot be remachined if their mating surfaces have been pitted by rust and as a result, the bare mating surfaces are often ruined by rust resulting from condensation.
I don't know what happened to the first unit that the customer received that locked up but in the case of the second, the technician rebuilt a transmission that had considerable rust on the majority of its internals. When I opened up the case this is what I found:
The dark brown coloring on the faces of the gear teeth is rust. Deep, pitting rust. You can see it on both the input shaft (top) and the individual gears on the lay shaft (bottom). The gears, counting from right to left, are: 4th, 3rd, 2nd and 1st (which is out of the frame). It would appear that 1st gear had been replaced as it had no rust on the teeth.
2nd and 3rd on the lay shaft.
Above is the lay shaft 5th.
And this is the input shaft 5th.
Now you might question this: Why is this bad? The transmission worked. It had 12,000 miles on it. Well, if it didn't whine badly (and I am told that oddly, this one didn't), this is why its bad:
The brown coloration to the gear oil is rust residue that has settled out in the bottom of the transmission. That residue was eating the sychros and bearings alive. 2nd gear had long ago worn out, both the hub on the gear itself and the blocker ring. The bearing races are eaten up and I mic'ed the clearances of a few of the gears and sleeves and they are beyond spec. Although the gears were already bad due to rust.
So after evaluating the core: Only 1st gear is usable and it's sychro hub is marginal. The input shaft and gearset are ruined and all of the bearings are unusable. Even the pinion shaft gear is worn to the point I probably won't ever use it. So what's left. The case, a few miscellaneous parts that typically don't fail and the diff carrier. Except, it appears the case may not be good either. The customer noted it had a severe oil leak along the mating seam. This rebuild had used a paper gasket which can cause such a leak over time and why I rarely use them any more. But on inspection there may be a crack in the back case half which was likely caused when an unused portion of the case was broken off. That section if often broken off and I regularly use similar cases because it is so common. But it is necessary to thoroughly inspect the case for cracks there. They don't often crack from the break but its the most common place for a crack to occur. I have to thoroughly wash the case and use some dye to detect the crack. I'll probably do that this weekend.
I hate to find things like this. The customer didn't get what he had expected and the vendor probably didn't supply what they had thought they were. Not to mention the vendor had already had to replace one unit. And the customer had to pay to have two units installed instead of one. All because the technician didn't have the knowledge and skill to do the job correctly from the outset.
All of this to make a simple point. When you're shopping for something (whatever it is) cost does not always equal value. So spend your hard earned money wisely. I have learned this lesson myself more than once. And probably will again. But I try not to repeat mistakes when I can avoid it.