Friday, July 04, 2008

Summer Teeth

Previously on the Man and Machine Blog viewers will recall that our intrepid duo were having a bitch of a time with their '67 Chevelle, specifically that it was spitting out broken parts with alarming regularity.

To backtrack just a touch, the 'Velle and scrubbed a cam love and required a new cam and all its attendant parts and pieces. We got that handled ("Applause" sign blinks on.), and Ben made it to the drag strip one or two more times after that. During one of those trips a stud for the right rear wheel stripped in the end that goes in the axle, meaning that when you try to remove the nut and take off the wheel the stud just spins in place and you can't remove the nut. This is a problem when you're trying to swap the drag slicks out for street tires so you can drive back home.

Since the drag slicks are legally street tires, Ben was able to drive the car home with the race meats in place (Don't try that at home, kids, it's a "loose" ride). A few days later I got the nut cut off with a Dremel and carbide cutter. Ben came over one night after that while I was away, and when I returned home I found this on the stove (click/enlarge):
For the ocularly challenged: "Tom, Got the stud pulled in using your method. Now the shifter is fucked. It won't stay in neutral and is acting generally gay. I hope it just needs to be adjusted. Ben"

Having read the previous post, you will already know the answer was a resounding "like hell!" Adjustments made no difference, and the phone came off the hook while the mouse clicked away on the 'net in search of possibilities for a swift and cheap repair to our tranny problems. We lost on both counts.

My good buddies at the fabulous site Team Chevelle helped me determine that there was much doom and gloom in store, and that we had to remove the tranny at the very least, and likely a rebuild was in store. Yay. I did not dance about this, should you be wondering.

Since the Goodguys Hot Rod Nationals were fast approaching at O'Reilly Raceway Park, we wanted the car done by then. Since we'd never done this work before, we agreed that having a professional do the work would be the quickest way to make sure it was done - if we could afford it. We took our lump of busted Muncie over to a local tranny shop. They quoted us 900 bucks. We groaned. A rebuilt Muncie of higher quality than ours is only about 400 bucks more than that. Parts for ours ran to six hundred. We could not afford 300 bucks for labor. Ben went and got what was now a box of Muncie parts.

By now it was obvious we weren't going to get the beast up and running for the Goodguys show. There was much unhappiness. Come the weekend of the show, however, it rained most of the time, so we felt okay about not missing much. Given all this, it was decided that our only realistic option was to do it ourselves. The guys at Team Chevelle had told me that "if you got that out of the car, then you know enough to rebuild it. It's easy." Um...okay, if you say so!

Ben swallowed hard and got on the phone. He ordered parts and footed the bill, for which I am heartily grateful, as this summer finances are very slim.

The most expensive single part is pictured below, the input shaft. The shaft portion of the part was really completely fine, as were gear teeth for fourth gear. Because of this, Ben said, "Maybe we'll be able to not use this and send it back." The synchro teeth that mesh up with the slider, however, well, take a look at the image below of the top/new part and the bottom/used part (click to enbiggen):

As you can no doubt see, those very small teeth in the bottom image remind me of the "summer teeth" joke: Som'er there, some're not. We hadn't totally sheared off any teeth, but LOOK AT 'EM! There are big chunks missing! If the synchros hadn't failed and jammed up the tranny in multiple gears at once, we surely would have destroyed this thing before the end of the summer. It was a difficult choice (this piece costs one-eighty all by itself, and was a huge dent in the total bill), but we went ahead and replaced it.

Our automotive back alley dentistry continued into other parts of the transmission as well. The image below is of the interior of one of the two sliders that we replaced. The little red circle (clicky to enlarge if ya like) indicates one of the more seriously damaged/chipped teeth on the sliders. The others are all rounded off at best, chipped and similarly mangled at worst. If we didn't race this thing it would probably have outlived us both. However, if we didn't race it we'd need to find something else to break and pour money into, and this car is pretty cool, so why not have fun with it?

And below us here we have a stellar example of a trashed synchronizer ring. See the green circles? Those are nice, new, well-formed parts of a synchro ring. See the red circles? Bad. Very bad. (click/enlarge the destruction) When I was looking at them, having never seen one up close before, I went, "Huh, that's kinda cool. They put little ridges on there so that it would slide toward that slot if you missed it on a shift." Um, no. Those ridges are there because it was repeatedly SLAMMED into gear at upwards of 6000rpm. Can you dig that, kids? Well, can ya?

What is not so easy to see in the pic is that the little teeth around the outer perimeter of the ring are also all damaged. None were broken off, which genuinely surprised me, but they were all rounded off. Much of the brass from the ring damage indicated here ended up in the sliders, and when sliders get handfuls of brass filings in them, well, they don't do what their name implies. When sliders don't slide you end up getting sorta/kinda stuck in two gears at once, or at least that's what it seems is happening. It feels like you can't select any one, single gear, and they are very hard to select if you can make that happen. We couldn't get it into neutral either, because the general bad shape of the rings was causing interference with the main shaft and locking the gears against the shaft. The gears couldn't freewheel on the shaft anymore with all those filings roaming around in there. Poor tranny, it never stood a chance against Ben's mighty powershifting capabilities.

In my next post I shall detail a bit of the rebuild, trying not to bore you mightily in the process. I'll put up some fun pics, now that I seem to be getting the hang of this site a little better, plus figuring out some niftiness with Photoshop Elements a little better.

As an added future bonus, I'll not here that Ben made a video of the entire friggin' rebuild process, and he says it will be available on the web in the future, and I believe it's not even gonna cost ya! So, if you're curious about this sort of thing, you can see what two total Muncie rebuild greenies went through to get this thing back down the track.

Happy Fourth of July!

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