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04-08-2020, 03:37 PM | #21 | ||
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Join Date: May 2010
Location: Eastern Tennessee
Posts: 11,486
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Re: Rear end ratio-gear question
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Yes, I agree with the hypoids sets being lapped however nothing that I have ever found in researching this has ever given any proof that Ford lapped them during Model-A production. I would expect this would have been an expense he was unwilling to include, and I am certain this is the major contributor to why 600wt. lube was used in the transmission & rear ends. With the higher viscosity, they would not have needed to have a lapped tooth to still be quiet. Yes John, I have on a couple of different occasions. In one instance, my father drove a '29 Phaeton to the MARC Nationals in Jacksonville, FL. En route, the pinion bearings came apart and killed the R&P gears. We sourced used parts from several vendors in the swap meet and the mis-matched gears were assembled. That assembly was as quiet as a mouse. Another time was on the Great Race when a team from Iowa broke a tooth on a drive gear. Parts came from everywhere that night from local hobbyists and we assembled it and it did well. With the proper weight lube, and the backlash correctly set, you should not experience any issue unless one of the gears is severely worn. |
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04-08-2020, 04:01 PM | #22 |
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Join Date: May 2010
Posts: 1,304
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Re: Rear end ratio-gear question
Thanks Brent ,good info, so he should keep rolling until he does a full rebuild .
John |
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04-08-2020, 04:10 PM | #23 | |
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Join Date: May 2010
Location: now Kuna, Idaho
Posts: 3,774
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Re: Rear end ratio-gear question
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Or see your local GM dealer for some Gear Marking Compound. It's a yellow paste of the right consistancy. |
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04-08-2020, 05:06 PM | #24 |
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Join Date: May 2010
Location: Oregon
Posts: 1,369
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Re: Rear end ratio-gear question
Helped a fellow with a noisy rear end some years ago. On inspection, the pinion was bad because the pinion bearings were shot. He found a rear axle lying in the weeds in a vacant lot and pulled the driveline/pinion from it. I was skeptical, having become accustomed to seeing matching ring/pinion sets in every rear end I opened. We assembled it with new bearings, checked the contact with Prussian Blue paste, and installed it in his coupe. To my surprise, it ran quiet and smooth. Maybe we got lucky?
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04-08-2020, 05:08 PM | #25 |
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Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,371
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Re: Rear end ratio-gear question
A person can run a higher numeric gear ratio and install a Mitchell overdrive if you want the best of both worlds. Back in the day they would have likely used an under/over gear box but that would have been more for pickups or trucks. With a speedster, the sky is the limit.
The gear marking compound is made from yellow pigment (pastel chalk as was mentioned) and synthetic oil mixed to form a paste. I started making my own back when red lead was no longer available. In packaged form, it's available from gear shops, Summit, and Jeggs plus many others. GM has a part number and there is an AC/Delco number but I don't worry too much about where it comes from. I just don't want to pay a lot for it. It works pretty well. I liked red lead paste better but such is life. Last edited by rotorwrench; 04-08-2020 at 05:28 PM. |
04-08-2020, 06:53 PM | #26 | |
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Join Date: May 2016
Location: Glide, Oregon
Posts: 1,334
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Re: Rear end ratio-gear question
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04-09-2020, 04:41 AM | #27 |
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Join Date: Dec 2013
Location: Mossel Bay, about 300km from Cape Town
Posts: 530
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Re: Rear end ratio-gear question
Hi John,
I have also replaced a 4.11 set with an unmatched 3.78 pair in my RPU. I got the two parts from two different guys, they looked like a match with no apparent wear. It runs smooth and quiet apart from the other noises a Model A makes. Take care and be safe guys.
__________________
Regards Chris Cape Town 28 Model A RPU, 29 Chevy Phaeton, 67 E Type FHC, 67 250SL Pagoda, 83 911 SC |
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