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Just got the transmission back in....

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bugedd

bugedd

Jedi Knight
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And drove it for the first time in three months! darn it felt good, even with the cold and the threat of rain.

I just rebuilt a rib case trans and got rid of the trashed smooth, and now I actually get all my gears. First gear in the smooth was so shot I was never able to use it. And I used one of the speed bleeders on the clutch slave, and it made quick work of bleeding with only one person. A very nice invention.

Now for a couple questions. First gear is loud. Very loud. Then again, its a straight cut gear so it should be loud. Is that typical? Third gear is a bit louder than second, and 4th is silent. All the gears are used, but nice ones from Mike Miller. The layshaft, bearings, syncros, etc. are all new Moss parts. So I guess I am wondering if it is normal for these trannys to be whiney, and do they break in a bit after a rebuild and quiet down?
 
1st gear is just plain loud. Enough said. Rest should not be.
 
IMO, mixing old with new is the source of noise in the intermediate gears. First is loud, no cure for that. Fourth is a straight through shot, so no gears with a load involved.

Old and new may wear in with reduced noise......eventually.

Turn the radio up.
 
Radio? whats that? Actually I have been thinking about putting one in, just don't know if the generator can keep up :smile:
 
I had the same experience with my rebuild last year, 1st was about as noisy as 2nd and 3rd, but fourth was quiet. After 1000 miles, it is a little better, but not much. This was a mixture of parts, all replaced except input shaft, but what is a person to do, as some are just not available from the regular sources. Can one blue the gears and then check the wear patterns? Then what do you do? Do any rebuilders have a test setup where then can run the transmission and check for noise?
I gave up when no one had a good idea what to do, except it will get better! I learned to hate videos of spridgets, as most were just noisy in 1st. I'm on the way to the dark side with a datsun trans!
Scott in CA
 
The Tunebug is noisy enough that I've never even noticed if the transmission is loud -- the engine/exhaust/rattles pretty much cover it up.
 
The rear diff in my midget howls on over run. I keep thinking that I'm going to fix it, but instead I just try to keep accelerating. :wink:
 
It does feel good to get back on the road doesn't it!

Don't think any gear in Edd's rebuild was really "new". More of an "Old" and "Older" relationship. Never had a Spridget gearbox, even very new, be as quiet as the modern all syncro stuff. Had a few builds where I could even hear the 1st gear whine over the race car exhaust. So, the radio solution and driving in 4th gear most of the time sounds like the best. Lubrication experimentation may help with the noise. Might tone it down a bit. Just don't use 90w gear oil. Some of the synthetic lightweight gear oils like Redline has might be worth a try. They are closer to conventional motor oil weights.

Don't think any rebuilder ever had any kind of test setup. Maybe the factory did back in the day. Even the quietest 1st gears were still pretty whiney.

Along with the gears, don't forget the cases and mainshafts have 36+ years use/wear on them too. So, we are stuck with what we have.

I'm trying to put together a Webster/Hewland geared conversion racing gearbox this week. All sorts of little issues with this one every time I pick up a different piece. Looks like I need some more machining on the main shaft to make it work. Gotta love it!

Mike Miller
 
When it comes to lube, I was told to use Castrol Hypoy C. I've seen many opinions as to what to use for oil, but no evidence to support. Mike, whats your thoughts on gear oil?
 
I don't recommend conventional 90wt gear oil. Check the factory shop manuals and I don't think they recommend it either. A good 20w50 is my preference. For driving in cold weather (<35 deg F), a 5w30 is a good option. Redline makes some light weight gear oils that are completely different from conventional 90wt. They are quite a bit thinner. Haven't tried them myself, but have used them in other racer's boxes.

IMHO, the stock type gearboxes were originally designed to use motor oil and that is what should be used. 20w50 is a very flexible product. Use it in the engine, gearbox and the dashpots. Leave the 90wt for the diff.

Mike Miller
 
Interesting, 20/50 is pretty thin stuff. I read somewhere people are using a 30wt product of sorts as well.
 
25/50 is what I'm running as well (engine/dashpot/transmission). That's what the original specs called for.
 
Good heavens, don't use gear oil in the transmission! I don't have any firsthand experience on what happens if you do, but there are plenty of stories out there where people claim it has actually ruined the transmission.

The Bugeye shop manual calls for 30 weight oil; my Haynes manual says 20w/50 for all but the 1500. Most people just use the same thing that they use in the engine.

There isn't a huge difference in viscosity between 30 weight engine oil and 80 weight gear oil, believe it or not. The viscosity scales are different.
 
Okay, just swapped out oil for 20/50. Now for the question, what is the difference between gear oil and motor oil when used in the gearbox? If 30w engine oil and 80w gear oil are about the same viscosity, then why one over the other?
 
Has to do with the way and material the inards are made of.

It is not the viscosity as I under stand it it is the shear stregenth of the lub.

But then what the heck do I know, I can't even spell engineer. In fact my wife says I know less every day.
 
That's a good question. I seem to remember that someone here explained the difference a while ago, and why our boxes don't use gear oil; maybe you can do a search for the post. But the two are obviously different--just smell the stuff and it will tell you that!

Also, see https://en.wikipedia.org/wiki/Gear_oil for a partial answer.

Oh--did the change in oil reduce the noise?
 
I don't know if it did anything, its been raining all day. Hopefully tomorrow I will be able to drive it to work and see how it goes.
 
For mine, I changed from 20/50 engine oil VR-1 to 60 wt VR-1 engine oil, and it quieted it down a bit, but not sure if it was worth the effort.
Scott
 
While the weight is the same, the way motor oil and gear oil react to the brass synchos (balk rings in lbc parlance) is different. the "book" shows to use the same weight oil in the tranny that is used in the engine, dependent upon ambient temperature considerations. The simple (and best rule) is to buy your engine oil a case at a time and use it for both engine and transmission. (Unless you've got a 5 speed)
 
Thats it Bill, the balk rings. The heavy oil does not allow them to work correctly they stick.
 
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