Rear gear set

Coronet67guy · May 24, 2020

Hi All,
Toying with the idea of replacing my gear set to get some more power to the rear wheels. Wondered if you guys could give me some suggestions/thoughts based on the following information.

400 Motor. Dual plane intake Adding shorties next week with TTI H pipe. Car will be 2.5 inches front to tips. Previous owner switched out cam to an Erson. RPM range 1800-4800. Other than that pretty stock motor.

Currently running stock tires and wheels, so figure a 26 inch tire diameter.

Mainly a street car, no plans for drag strip, so thinking not to extreme. I want the car to still be a good highway cruiser.

Rebuilt 727 with transgo shift kit.

Current set is stock 2.76. 489 case. No sure grip.

I'm leaning towards Yukon 3.23 from Fllthy motorsports. Yukons tend to run higher than say a US Gear or Richmond. Worth it? And on the overhaul kit, I've seen some that cost almost as much as the gears themselves. What do you really need? I'm thinking one of the cheaper "minor overhaul kits" and picking up the Timken bearings separately.

Fran Blacker · May 24, 2020

I ran 3.55's for years great all around ratio.

69L48Z27 · May 24, 2020

Yeah, I wouldn’t do anything numerically lower then 3.55 personally. If you’re going to do a a lot of ‘highway’ then maybe go 3.23. I personally don’t think spending more is worth it for Yukon. Richmond and Motive are the same company I believe. I would re-bearing the entire rear. Really the only thing you can get away with not using in a kit are the ring bolts. Some thing they have to be replaced every time.

Coronet67guy · May 24, 2020

69L48Z27 said:
Yeah, I wouldn’t do anything numerically lower then 3.55 personally. If you’re going to do a a lot of ‘highway’ then maybe go 3.23. I personally don’t think spending more is worth it for Yukon. Richmond and Motive are the same company I believe. I would re-bearing the entire rear. Really the only thing you can get away with not using in a kit are the ring bolts. Some thing they have to be replaced every time.

Thanks for the input. The common complaint I see in negative reviews on the Richmonds is noise. This is a great chart from US Gear that has helped me narrow it down. If I threw some 215's on the back I could increase my tire diameter and get me closer to 27 inches. Right now 3.55 with 26 inch diameter tires is right on the edge of acceptable. (According to the chart anyway)

https://www.usgear.com/usg-admin/resources/literature/ratio-chooser-1.pdf

67charger383 · May 24, 2020

I

Coronet67guy said:
Hi All,
Toying with the idea of replacing my gear set to get some more power to the rear wheels. Wondered if you guys could give me some suggestions/thoughts based on the following information.

400 Motor. Dual plane intake Adding shorties next week with TTI H pipe. Car will be 2.5 inches front to tips. Previous owner switched out cam to an Erson. RPM range 1800-4800. Other than that pretty stock motor.

Currently running stock tires and wheels, so figure a 26 inch tire diameter.

Mainly a street car, no plans for drag strip, so thinking not to extreme. I want the car to still be a good highway cruiser.

Rebuilt 727 with transgo shift kit.

Current set is stock 2.76. 489 case. No sure grip.

I'm leaning towards Yukon 3.23 from Fllthy motorsports. Yukons tend to run higher than say a US Gear or Richmond. Worth it? And on the overhaul kit, I've seen some that cost almost as much as the gears themselves. What do you really need? I'm thinking one of the cheaper "minor overhaul kits" and picking up the Timken bearings separately.

I bought the Yukon rebuild kit and Yukon 4.11 gears for my 742 suregrip and they were great quality and made in the usa. Went together pretty easy once I figured out how to do it. I basically got it for free because I won the money in a class action lawsuit for my old smartphone. (Nexus 6p)
My only complaint I had about the kit was that the 2 main carrier bearings were the wrong size and I had to buy new ones, but everything else in the kit was right. I actually ordered the elite gear and rebuild kit from eBay but I got like $600 worth of Yukon parts instead. Think the seller fucked up

Coronet67guy · May 24, 2020

67charger383 said:
I

I bought the Yukon rebuild kit and Yukon 4.11 gears for my 742 suregrip and they were great quality and made in the usa. Went together pretty easy once I figured out how to do it. I basically got it for free because I won the money in a class action lawsuit for my old smartphone. (Nexus 6p)
My only complaint I had about the kit was that the 2 main carrier bearings were the wrong size and I had to buy new ones, but everything else in the kit was right. I actually ordered the elite gear and rebuild kit from eBay but I got like $600 worth of Yukon parts instead. Think the seller fucked up

I ran a Yukon upgrade in a 73 charger I used to own, had no complaints. Ran 3.23's but that was just a beefed up 318 car. Sounds like you got a hell of a deal from the eBay guy! I just wasn't sure if the "master overhaul kit" that costs over $200, is really needed. I can buy the "minor overhaul kit" for $75 and pick up the bearings for about $30. I'm sure there is more that the minor kit is missing though.

Demonic · May 24, 2020

A common mistake is that the Sure Grip/Auburn/spool carrier bearings are larger than an open rear. If you look on US Gear's website, the list of bearing sets have details describing applications. Do not cheap out on a bearing kit, you will eventually replace what you skip. Why do it twice? Stick with the 3.23's if you like the highway and long trips. I am partial to my 3.55's, but on a long trip at 65-70 mph they get a little "buzzy" - more rpm than the average car.

https://www.usgear.com/products?cat=bearing-kit

Coronet67guy · May 24, 2020

Demonic said:
A common mistake is that the Sure Grip/Auburn/spool carrier bearings are larger than an open rear. If you look on US Gear's website, the list of bearing sets have details describing applications. Do not cheap out on a bearing kit, you will eventually replace what you skip. Why do it twice? Stick with the 3.23's if you like the highway and long trips. I am partial to my 3.55's, but on a long trip at 65-70 mph they get a little "buzzy" - more rpm than the average car.

https://www.usgear.com/products?cat=bearing-kit

Thanks for the info. The US Gear kits are more reasonably priced then the Yukon. I'm assuming you could use a US Gear kit with a Yukon set. I did plan on purchasing quality Timken bearings if I did't get the full kit that included them. Sounds like you're saying to purchase the full "master overhaul" kit and don't look back. I wouldn't be looking at any long trips. Just probably a 50/50 mix of city and highway. I feel like both ratios would work pretty well with my set up.

Demonic · May 24, 2020

If you plan on driving to Carlisle, or Woodward, or Bonneville, etc, go 3.23. If you're sure you would trailer to such an event, go with the 3.55's. They're more fun-er!

Coronet67guy · May 24, 2020

Demonic said:
If you plan on driving to Carlisle, or Woodward, or Bonneville, etc, go 3.23. If you're sure you would trailer to such an event, go with the 3.55's. They're more fun-er!

Yes, I would never drive it that far. Trailer would work! So on the US Gear kits when would you need the 1031R with the rare side bearings and races? I've noticed the price is the same as the 1031 so I don't see a reason not to get the 1031R. Thanks!

Fran Blacker · May 24, 2020

Drove my Satellite 360 miles from Ct to Niagara Falls with 3.54's 26.5 tires. 3200 rpm at 68mph and got 14 mpg as long as I didn't open 2nd 4 barrel. Had a 64 Olds Starfire vert with 3.55 standard equipment. It was Olds sport luxury model.

Demonic · May 24, 2020

It's not about price, it's which bearing race dimensions match the carrier you have. Sticking with your open carrier?

Changing ratios is the best time to upgrade to a Sure-Grip. The bearing cup OD is the same across all the carriers - any Sure Grip can swap to any carrier - 741, 742 or 489, as long as the carrier bearing come along too.

good info: http://www.mymopar.com/Mopar8_75RearEndGuide.htm

Coronet67guy · May 24, 2020

Fran Blacker said:
Drove my Satellite 360 miles from Ct to Niagara Falls with 3.54's 26.5 tires. 3200 rpm at 68mph and got 14 mpg as long as I didn't open 2nd 4 barrel. Had a 64 Olds Starfire vert with 3.55 standard equipment. It was Olds sport luxury model.

Very nice. How was the ride? I've pretty much decided on 3.55's. Probably US Gears with their bearing kit and installation kit. Just not sure if I need the 1031 or 1031R bearing kit. Total cost about $460 at Summit.

dadsbee · May 24, 2020

3.55's in the Bird. Atlanta Motor Speedway to Alexander City Alabama and to Talledaga and back. Was a great drive, like many other long drives in the car. That said, have a hard time not chirping the tires with those gears. My Bee has 2.94's in the back as I may have been a bit of a speed demon in my teens, vs the 3.23 it should have. Wish it had the 3.23 in it again, as highway right now I never put it in 4th on the 2.94's or I'm lugging under 2000 rpm.

Coronet67guy · May 24, 2020

Demonic said:
It's not about price, it's which bearing race dimensions match the carrier you have. Sticking with your open carrier? Changing ratios is the best time to upgrade to a Sure-Grip. The bearing cup OD is the same across all the carriers - any Sure Grip can swap to any carrier - 741, 742 or 489, as long as the carrier bearing come along too.

good info: http://www.mymopar.com/Mopar8_75RearEndGuide.htm

Thanks for the link. I've read that page a few times. I do plan to stay with an open carrier. I've looked at maybe doing a sure grip but money to spend is an issue as well as not really knowing what direction to go on finding one for my 489 case. I've seen eaton Detroit true trac's running over $600. I'm sure there are cheaper options that aren't the Torsen style but not sure where to start looking.

khryslerkid · May 24, 2020

Nobody mentioning Dr. Diff ?

Went with 3.23 ring and pinion by Nitro plus the Timken bearings plus the complete clutch rebuild kit for under $500 shipped. (742 Powr-Lok)

Subtract $80 for the clutches if you're staying with the open rear.

Gears are quite as a mouse. :thumbsup:

BIGSHCLUNK · May 24, 2020

3.23' s on the hi way, all day!

Coronet67guy · May 25, 2020

khryslerkid said:
Nobody mentioning Dr. Diff ?

Went with 3.23 ring and pinion by Nitro plus the Timken bearings plus the complete clutch rebuild kit for under $500 shipped. (742 Powr-Lok)

Subtract $80 for the clutches if you're staying with the open rear.

Gears are quite as a mouse.

This sounds interesting. I'm totally clueless when it comes to sure grip. I've never owned a car that wasn't open carrier so not sure what exactly I would need to purchase to convert. Here's what I see.

Power-lok clutch type sure grip - $395
3.23 or 3.55 ring and pinion. $185. (I only see Dr. Diff/Hooser brand for 3.23, and Motive/Richmond for the 3.55)

So I'm already in well over 500 and don't have all that I need.

Fran Blacker · May 25, 2020

Had a bit of a drone with 3.54's but mufflers weren't in good shape. Would put my 4 year old a sleep but not the 2 year old.

67charger383 · May 25, 2020

Coronet67guy said:
Thanks for the link. I've read that page a few times. I do plan to stay with an open carrier. I've looked at maybe doing a sure grip but money to spend is an issue as well as not really knowing what direction to go on finding one for my 489 case. I've seen eaton Detroit true trac's running over $600. I'm sure there are cheaper options that aren't the Torsen style but not sure where to start looking.

Think there's a 742 sure grip on eBay for $300. You'd need a new case tho.

Rear gear set

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