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Worn gears

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jcatnite

jcatnite

Jedi Knight
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Since most of my engine is at the machine shop, I decided to dive into the gearbox to see what was what in there. It was making a clicking sound when in an overrun condition in first gear. Looks like my 1-2 synchro gear and the reverse idler aren't meshing very well. Not sure yet what would cause that but since the reverse gear floats on the shaft, I'm leaning towards the shifter? Any ideas?
Attached is a picture of what I'm talking about. In reverse it is cool but in 1st it makes a lot of noise..
JC
 

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Looking at the photo, it ~appears~ the first gear and the reverse idler both look kinda worn, but that wouldn't necessarily make a "clicking" sound on "reverse" loads. Keep goin' and I'll guess you've got some bearings to replace.
 
I put it back together now that I know what I'm looking at and the reverse gear only has half a toothe engagement with the 1-2 synchro gear when I'm in 1st gear. I'm pretty sure these two gears and the standard bearings and bushings need replaced. I did notice that if I push the shifter past the detent towards 1st, the noise drops significantly. I think that is because I'm getting a little better tooth engagement there. This should be fun as it took me a 1/2 hour to figure out how the lockout spool went...lol. Finally moved the laptop out to the garage and pulled up the pics...
JC
 
Hey JC,

Mine does the same thing. On mine the noise is caused by the slack in the reverse gear idler "bush." When in first gear, the idler still barely engages the reverse/synchro gear (but not the laygear) so that it turns and clicks. Replacing the reverse idler will most likely get rid of the noise.
 
I'm going to have to buy a reverse idler and an outer hub/gear for the 1-2 synchro. I've also got to buy a speedometer gear since I pretty much destroyed it trying to get it off the output shaft...lol. even a small cobbling hammer (as my granddad used to call it) was a bit too much for the plastic. You should have seen the rig I put together to finally pull it off...lol But all the gears and shafts are on my workbench now so it is only a matter of time till it is all back together.
JC
 
I got lots-o-spare transmission parts lyin' around, so let me know if you need anything. Unfortuneately, the extra outer hub and idler I have are chewed up, too.
 
LOL, I think that is about all I need bud. Along with the typcial soft parts that I wouldn't think of replacing with used stuff. Thanks for the offer though.
JC
 
"cute" li'l gearbox, ain't it?

How'd your layshaft/bearings look?
 
Layshaft is great. Bushings look good and laygear assembly shows no wear. Problem is, it is a non-modified gearbox and apparently the 1/2 synchro hub is almost impossible to find. I can get a "modified" synchro hub and reverse idler but then I have to buy a new laygear assembly...(ouch). So, I'm looking for a "good" used gearbox or alternate source for the non modifed synchro hub. I've got plenty of time till she is back together so I can afford to be patient right now... But I have upped the ante a bit since I just bought a new Kent cam, new pistons, rod bushings, rod and main bearings, and water pump today. I may be getting desperate before too much longer...lol Oh and bearings in gearbox get replaced as a matter of course.
JC
 
Which cam did you get? I find the TH5 excellent for a really high compression (10.5:1) motor. However, Mark (silentunicorn) has found that his TH2, with much lower (I forget his number) compression has trouble off idle. Mine does have a bit of trouble too, but it pulls adequately above 2000 RPM and well above 2500 in 4th gear. It really screams all the way to 7000 (where I'm scared to tread). I've also got dual weber 40's, so that doesn't help the low-end torque. If you're running a stock intake or DGV, that might not be a problem.
 
I got the TH2 and I'll be running the stock 9:1 pistons. I'm keeping the Zenith so hopefully it will not be a big issue. The advertised power band for that cam starts at 2500rpm so I was a bit worried about it but I think it can be tweeked to perform well on the street.
JC
 
I wouldn't worry about it, it'll probably pull fine from a lower RPM, just not "in the band" for all practical purposes. With the zenith or an SU, it'd pull really well from down low, most likely and probably run out of juice before too long at the high end (a good thing for engine safety). 9:1 CR should give you a good compression for off-idle power. If you had the 7.5:1's, I can bet it'd be a real dog.
 
Yup, should pull like a mule. Just keep in mind you'd not want to "lug" it in any case. Nothing below 2K except first. It's got cogs, so you'll use 'em all proper-like /ubbthreads/images/graemlins/grin.gif
 
Yeah the engine is going to run strong <crosses fingers> but it's looking like the gearbox may end up being more difficult than the engine...lol. I wasn't really planning on dumping a half a grand into the gearbox. Thought I would toss some synchro rings and bushings inside and new clutch disc outside...best laid plans
JC
 
[ QUOTE ]
I got the TH2 and I'll be running the stock 9:1 pistons. I'm keeping the Zenith so hopefully it will not be a big issue. The advertised power band for that cam starts at 2500rpm so I was a bit worried about it but I think it can be tweeked to perform well on the street.
JC

[/ QUOTE ]



yep the power band aint there much below 2500..(just have to keep the rubber band wound up) i hope to get the hi comp piston and an exhaust in this summer. i have a pacesetter header, and would like to replace it with a better one. any reccomendations? would like one that already has the 90 on it......



mark

mark
 
Not sure Mark. I was planning on sticking with the stock exhaust for now. The rebuild budget has swollen to a point that I will have to hold off on some of the "nice to have" items and focus on the "must have" for now. I just pulled the pacesetter header off my list of parts still needed last night.
JC
 
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