(489) 3.23:1 to 3.55:1

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1badfish67

1badfish67

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My 67 Barracuda has a 489 case in it with 3.23:1 ratio running 26" tires. Also has 69 A833 A-Body 4 spd. It is some kind of locking diff I think, as when I backed it into my shop after getting it off the trailer from purchase the tires broke loose and left 2 even black marks on the concrete. It's uphill into my shop. Not sure if it's a Sure Grip or not. Diff is still in the car. I am thinking about trying to swap out the ring gear and pinion to a 3.55:1 ratio.

Would it be too much trouble to swap out the ring gear and pinion? If not, what would need to be done as far as setting it up? Would I need to just adjust/shim gear lash between the ring gear and pinion or is there a lot more involved even if I wasn't planning on completely stripping down the entire unit?

If it would just be adjusting the gear lash on the new gear and pinion does anyone have any recommendations as to brand(s) of gear set? I have glanced at Richmond but haven't dug too deep into the weeds yet. Gathering parts for the 340 engine (+0.030) rebuild right now. Shooting for ~ 400-425hp at flywheel. Thought it may need a stouter gear set for the hp? Not sure on the torque value yet. Some write ups I have seen online (Motor Trend) and such with similar build components as I have accumulated showed around 428 lb*ft of torque. I figure every engine will be a little different though.
Best I can tell from case casting number decoder(s) the tranny has a 2.66:1 first gear ratio, unless someone has possibly changed it out.

I know this is a long post but another thought was that if I kept the 3.23 as it is, would swapping the 2.66 first gear to a 3.09 be enough to make a friendlier low gear cruising experience. Don't want to have to keep clutching on a main street cruising night if I don't have to and not require over 3k rpm to run 70 mph on hwy.


Appreciate any thoughts/recommendations.
 
Were it my car, I'd probably find a 3.09:1 gearset for the transmission and leave the 3.23s if they're not making any noise. More yee-haw off the line but old familiar friends in the next three gears. That being said, unless I'm looking for silly drag-strip/wheelie-poppin' gears, I try to get OE gears, either good used or NOS. There's never been a question of noise, and they're as durable--if not moreso--than the aftermarket stuff. Avoid Richmond's Pro series unless you plan on constantly dumping the clutch. They're a little softer to absorb extreme use/abuse, but they're not 50,000 mile gears. They wear more quickly, which Richmond clearly mentions.

I've built a few dozen 8.75" center sections and have always just used the rear shim (between the pinion head and the rear bearing) that came from the factory with the case I'm using (not the gears). I've never had reason to fiddle with the pinion depth doing that. Others may have not been so lucky.
 
I came up with 2923 rpm @ 70.00 mph for the 3.23 and 3213 rpm @ 70.01 mph for the 3.55. Pretty close.
 
The biggest headache will be setting pinion depth in my opinion. I used "hollowed out" inner & outer pinion bearings that would slide on & off while I swapped out shims to get the right pinion depth. I used the bearings that came off the pinion & used a stone on a drill to "hollow" them out. Otherwise you'd be pressing the bearings on & off. The good thing is, setting ring gear backlash is a breeze due to the side adjusters. You can do it, just takes a lot of patience. I built a 9.25 axle in my Duster & setting it up is similar. I'd suggest you get a service manual for a vehicle with the 8.75 axle. If you know someone who works at a shop that has All Data, they may be able to print the procedure for you if All Data goes back to at least '72 when Dodge trucks still had that axle. That was my reference years ago. Good luck!
 
NoCar340 said:
Were it my car, I'd probably find a 3.09:1 gearset for the transmission and leave the 3.23s if they're not making any noise. More yee-haw off the line but old familiar friends in the next three gears. That being said, unless I'm looking for silly drag-strip/wheelie-poppin' gears, I try to get OE gears, either good used or NOS. There's never been a question of noise, and they're as durable--if not moreso--than the aftermarket stuff. Avoid Richmond's Pro series unless you plan on constantly dumping the clutch. They're a little softer to absorb extreme use/abuse, but they're not 50,000 mile gears. They wear more quickly, which Richmond clearly mentions.

I've built a few dozen 8.75" center sections and have always just used the rear shim (between the pinion head and the rear bearing) that came from the factory with the case I'm using (not the gears). I've never had reason to fiddle with the pinion depth doing that. Others may have not been so lucky.
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Thanks.
I was planning on having someone go through the tranny anyway to inspect gears etc, add new bearings and synchros.

I keep seeing NOS on a lot of posts. What is NOS?
 
srduster340 said:
The biggest headache will be setting pinion depth in my opinion. I used "hollowed out" inner & outer pinion bearings that would slide on & off while I swapped out shims to get the right pinion depth. I used the bearings that came off the pinion & used a stone on a drill to "hollow" them out. Otherwise you'd be pressing the bearings on & off. The good thing is, setting ring gear backlash is a breeze due to the side adjusters. You can do it, just takes a lot of patience. I built a 9.25 axle in my Duster & setting it up is similar. I'd suggest you get a service manual for a vehicle with the 8.75 axle. If you know someone who works at a shop that has All Data, they may be able to print the procedure for you if All Data goes back to at least '72 when Dodge trucks still had that axle. That was my reference years ago. Good luck!
Click to expand...
I have the patience. Friends and supervisor at work say I'm a little over detail oriented for them. Haha. I believe GIGO.
 
NOS. Thought it may have been some kind of remark on 'Overseas" parts. Good thing I didn't post what I thought it meant!
 
Was the spline teeth count on yoke standard on OEM gear set for the 489? Haven't pulled mine to count.
 
Here is what the 489 8 3/4 gear set looks like inside.
Clutch Style Sure-Grip and Pinion and parts on white paper towel.

Yes it's a major go through and set up for changing the ring and pinion.

20191216_194809.jpg
 
1badfish67 said:
Was the spline teeth count on yoke standard on OEM gear set for the 489? Haven't pulled mine to count.
Click to expand...

No. Very-early 489s had a 10-spline yoke, but within a year they went to the 29-spline. It's not common to find 10-spline factory 489 gears, but the aftermarket did make them too. I don't think I've seen an aftermarket 3.23 in 10-spline, though.
 
Depending on what your ultimate goal is for the car, I'd honestly leave the 3.23s in it until you've driven it a while. They're an excellent street gear, and a lot friendlier behind a 4 speed than you may realize.
 
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leave the 3.23s up the tire to 27 inches put a 150 shot on it
i ran that combo both 4 spd and auto
243@50 cam it was a rocket on the hi-way :)
 
My brother was going to give me his nitrous kit that he wasn't using anymore. Injects via carb spacer. Heard from a few folks that it may be necessary to file the ring gap a little wider if you're running a nitrous kit? They didn't specify a Hp shot size though. Something like a min of .004" per inch of cylinder diameter?? I was looking at a Comp Cams 230/236 @ 0.050. I believe it was their XE274 cam.

I may give the 3.23 a try and see how it does. Just thought if 3.55 gear and pinion weren't too costly I may try to pick it up just to have it in case I wanted to try it. May still go with the 3.09 first gear setup for town cruising and as NoCar340 said a little harder giddy up out of the hole.

Thanks everyone
 
for the 300 rpm difference between 3.23 and 3.55 gear set i do not think it is worth the time or money to change i do not think you will feel the difference , now going to maybe a 3.73 gear and you have made enough rpm difference to feel it. as far as gear company to go with see September 26 2022 post on the E-body site in transmission and drivetrain titled 8-3-4 with 742 house.
 
john-9 said:
for the 300 rpm difference between 3.23 and 3.55 gear set i do not think it is worth the time or money to change i do not think you will feel the difference , now going to maybe a 3.73 gear and you have made enough rpm difference to feel it. as far as gear company to go with see September 26 2022 post on the E-body site in transmission and drivetrain titled 8-3-4 with 742 house.
Click to expand...
Thanks
 
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