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Discussion Starter #1 (Edited)
You guys might remember the post about the flywheel studs.... Well, finally got everything together!

Car is the one in my signature. Pump gas, flat tappet 6800 rpm 306 with a 200 hp plate and 4.30 gears.

Anyway... Updated the small in/out trans to a big in/out configuration. Got it together, drove it around about 20 miles doing plenty of shifting, got the oil nice and warm... then changed it out. After this, straight to the track!

First pass off the trailer in 90 degree heat, it ran a 6.36 @ 106.8 mph in 90 degree, hot miserable, max humidity weather. Had a 1.36 60 ft. I guess in the dark on the clutch, so I was really happy!

Next run, I missed 2nd gear... which is a rarity. Don't know if it was me or the trans. Next run it stuck in 2nd gear! Took it apart today, and 2nd gear was SEIZED to the main shaft! Had to crank pretty hard on my 20 ton press to get them apart! 3rd/4th snchro dogs also got beat up somehow. May be related to the seizure?

Trans is a stock toploader... Same transmissions I've been using for 30+ years without issue. Only main changes were a brand new aftermarket main shaft, new 2nd gear and new syncro assemblies. Also tried a new brand of oil... Penn Grade 80w90 GL-4.

Any ideas?





 

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Discussion Starter #3
Powerglide.:smt102



JK.......did you use asssembly lube when you had it apart?
Yep. Plus, it had around 20 miles on it, and lots of shifts. Oil was changed after that 20 miles as well. Everything else looks great.
 

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Discussion Starter #5
Think I'd go back to your original oil.
Yes... That's a given. I used Valvoline before. You hear a lot of good things about the green Brad Penn oil... at least their engine oil. You hear chatter of using GL-4 in these old transmissions instead of GL-5... To be safe, I'm going back to the Valvoline, as that's what has worked for me before. This PennGrade GL-4 is what David Kee sells and recommends for his toploaders... so I decided to try some.

This being said, I'm not sure it's the oil. Was looking for any other input anyone might have.

Thanks Guys!
 

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LOW OIL will do that in a top loader
 

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Been many moons since I ran a stick. Used to weld first gear at times. If I remember I had to cut some oil grooves in them to allow more oil in. Also, like an engine, verify the clearances between the gear and shaft. I believe that I used to talk to Liberty to get help. Sorry that I don’t remember more details.
 

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Discussion Starter #8
Been many moons since I ran a stick. Used to weld first gear at times. If I remember I had to cut some oil grooves in them to allow more oil in. Also, like an engine, verify the clearances between the gear and shaft. I believe that I used to talk to Liberty to get help. Sorry that I don’t remember more details.
Stock main shafts have diagonal grooves across the bearing surface. These just have the one in the center... which could possibly be an issue. That being said, I have an old aftermarket 9310 31 spline main shaft from back in the day that was a custom racing piece done by Tom's Differentials. It was top of the line back in the day, but takes weird circle clips that I didn't have... so I used this one. The old one also only has the center oil groove, and no diagonal.

Unit was definitely full of oil. They take 2 quarts.

Gear 'felt' good on there, and rotated nice and freely. Felt like any of the other gears I've installed on numerous toploaders. No drag in its rotation. Will have to pay close attention to clearances, and maybe do some more oiling mods. I did grind another feeder groove in this one, and chamfered the oil holes like I always do. I also check the gear's side clearance, and adjust them to 0.015" to 0.020". This is something most people don't do. In 30+ years, I've never had an oiling issue.
 

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That's lighter oil then I would use. Are the gears bushed?
I ran redline heavy high shock in my hemi box.
Have a G101a now and was told to use Mobil synthetic 75w 140
 

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Discussion Starter #10
That's lighter oil then I would use. Are the gears bushed?
I ran redline heavy high shock in my hemi box.
Have a G101a now and was told to use Mobil synthetic 75w 140
It's still a basically stock trans, so it still has synchros. The gears are not bushed, but I've never had a problem like this in 30+ years. Synthetic oil is not recommended for these toploaders. Supposed to be too slippery for the old style synchros. Who knows...

Those G101A's seem to be pretty nice transmissions. I may outgrow the toploader, but still need a street trans... as the car sees a lot more time on the road than the track.
 

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If I remember right, stock toploaders are not the smoothest shifting trannys. Do you do any mods at all to help the shift?
 

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My WR Toploader has synchro only in 1st with faceplated 2/3/4, sees 8500 fairly regularly with synthetic oil. Even been using the same stock SROD mainshaft for the past 8 years (WR 2nd gear hub narrowed and WR 3rd gear shimmed to fit). Never seen any sign of a gear/mainshaft oiling problem.

Grant
 

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I missed the synchro part. the dogs are from the gear getting stuck. missed shift was also probably from the seized gear.
With the new parts and light gear oil it might have been the reason it seized.
 

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Mike...I build a few of these were did you buy mainshaft and gear from?Same as you we had a stock one in a foxbody and beat it to death with no problems shifting at 7000
 

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Stock main shafts have diagonal grooves across the bearing surface. These just have the one in the center... which could possibly be an issue. That being said, I have an old aftermarket 9310 31 spline main shaft from back in the day that was a custom racing piece done by Tom's Differentials. It was top of the line back in the day, but takes weird circle clips that I didn't have... so I used this one. The old one also only has the center oil groove, and no diagonal.

Unit was definitely full of oil. They take 2 quarts.

Gear 'felt' good on there, and rotated nice and freely. Felt like any of the other gears I've installed on numerous toploaders. No drag in its rotation. Will have to pay close attention to clearances, and maybe do some more oiling mods. I did grind another feeder groove in this one, and chamfered the oil holes like I always do. I also check the gear's side clearance, and adjust them to 0.015" to 0.020". This is something most people don't do. In 30+ years, I've never had an oiling issue.

Stuska 1 has a couple of spare long tail shaft toploaders, one big input output close ratio (from a torino 429 cobra) the other small input output wide ratio with a big flywheel (428 type) cast iron bellhousing. contact him he might want to sell them.
 

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Discussion Starter #16 (Edited)
Thanks guys. I'll try and answer some of your questions...

As for smooth shifting... A toploader is a big, heavy, iron transmission. It's not a flyweight, feeble aluminum T5 with lightweight parts that can be shifted with your fingertips. That being said, it DOES shift fairly smoothly. If you shift it 'like a man', it will bang gears with any of them. lol

Never heard of using a SROD main shaft. I've considered the Faceplate mod from Liberty... and should probably send them some gears before they stop doing it! lol Would make for the ultimate Toploader that didn't balk at shifting at pretty much any rpm. Did you run into an rpm limit where the stock toploader didn't want to shift?

The gear oil used before was still 80w90... just a different brand.

Brand new main shafts are available from Dan Williams and David Kee. I believe they are likely the same pieces. I've always used stock main shafts, but wanted to upgrade to the larger 31 spline, and and didn't have a stock one here... as I've always run the smaller 28 spline units. (small input uses a C4 slip yoke, the large uses a C6 unit) I have no idea why it seized. Only obvious difference is the shaft's oil grooves on the bearing surface where the gear rides. The aftermarket unit has a single, central groove... where the stock one has diagonal grooves that span the entire bearing area. But, I have an aftermarket 9310 shaft from Toms Rear Ends who was the main supplier for 'built' toploaders back in the day... and his has that same single groove. It just takes some not commonly available clips that hold some of the gears. I tried to use that shaft first, but after some calls, found they were like big spiro-locks or something that have a much smaller radial thickness. 3rd gear is done differently on it. Liberty provided that info, but they didn't have any. Said they would have to try and match something up if they were building a trans with it... but remembered working with those shafts.
Here is a picture comparing a stock shaft, my aftermarket one that seized the gear, and the old 9310 unit from Tom's Rear Ends.



Here is a video of the car at the track. Trans doesn't shift bad for an stone stock antique. lol Some more fun street videos under my name there... Horsepower Therapy 1, 2 and 3. :)

 

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I ran a toploader decades ago small in/out 2.78. Stock it shifted OK up to 7000 rpm, over 7500 it became iffy. I did the redneck crashbox deal (grind every other tooth off the sliders and hubs, leave the 3-4 synchros out and turn the teeth off the 2nd synchro ring) and it shifted great to over 8500. That way, it was butter smooth to power shift, every shift felt like a missed gear because there was zero resistance at the handle and I never missed one. It also worked fine on the street, I usually didn't even use the clutch, just matched rpms.


I bought a Dan Williams mainshaft to convert it to a large output. Instead of the spiral grooves it had a flat on the bearing journals to let the oil in. Dan's explanantion was that the spiral grooves would wipe the oil off the ID of the gear and cause galling, the flat was better. Still have the shaft, haven't used it yet.



For lack of more info, your failure looks to me like there wasn't enough oil getting into that diameter, as if the clearance was too small. I'm following to see what you learn.
 

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I used the SROD mainshaft because I had one handy where the nose was in excellent shape. I have a lathe, so modifying gear hub width and adding a custom width spacer to make it work was no big deal.

I never even tried to run the Toploader with synchros. Did the faceplating here using Liberty TKO parts, made modifications as necessary to make it all work. Had to change the detent grooves in the shift rails, travel for engagement is quite a bit shorter than a stock Toploader. One other thing I did was to make stop sleeves for the shift rails as well, never had any problems with cracking the stock un-modified shift forks.

Grant
 

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Discussion Starter #20
mike were did you buy your mainshaft that failed?
I don't want to point any fingers just yet... as I'm not 100% sure of the cause of the failure. I got it from Dan Williams. I believe David Kee sells the same parts. He said he has sourced them from both Tremec and Jerico. It did mic about a half thou or so larger than the stocker. He said they work best with between 0.0020" and 0.0025" clearance. I've never really gone to the trouble of checking that before as long as the gear felt like it spun fine on the shaft, and had no drag. Main thing I adjust is the side clearance, as it is sometimes a bit on the tight side.

Have you had issues with gears seizing on the shaft before?
 
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