choice between stock 3.23 or upgrading to 3.55 or 3.91

[resq302]

Well, it seems like my rear is the culprit with the growling problem I am having.  I pulled the filler plug out and was able to catch some of the gear oil in a clear container and I saw some metallic flakes in the gear oil.  Also the gear oil is only about a year old since the rebuild on it and is ver dark in color.  What got me concerned was I saw a little chunk of metal, not big at all but a square piece of metal that was too big for my taste.  Since I am going to have to disassemble the rear again, I was considering upgrading my ring and pinion in my car to give it a little better performance.  I currently have a 489 casing in the 8 3/4" rear.  My car is a factory 4 speed tranny and it runs good now but I would like to have a little more pep and better trottle response.  If this was your car, would you leave the 3.23 stock ring and pinion gears in it, or would you upgrade to either the 3.55 or 3.91.  Looking at Summit racing, the Richmond Gear sets they have, the 3.91 is cheaper than the 3.55 for some reason.  I also have a sure grip unit in it that I took out of a 742 casing so the sure grip is the clutch type and not the cone type.

Your thoughts as to what I should do everyone?  Also, keep in mind, I am trying to do this on a very limited budget.

[Lightning]

if it's not driven more than 4 times a week I say go for the 3.91

[resq302]

Its driven for cruise nights and car shows only.  And the occasional stress reliever drive.

[71superbee]

I also had 3.23 gears and a 4 speed, I changed to 3.55 gears and I am totally happy with my choice. It has much better throttle response and will also cruise well on the highway.I would highly recommend the change !
                             

[Just 6T9 CHGR]

Brian with your small diameter tires I would go with a MAX of 3.55's

You will NOT be happy with the 3.91's

[694spdRT]

Brian with your small diameter tires I would go with a MAX of 3.55's

You will NOT be happy with the 3.91's

 

3.91's and up are best left to those with taller tires IMO.

[resq302]

Brian with your small diameter tires I would go with a MAX of 3.55's

You will NOT be happy with the 3.91's

Chris, just curious why would the 3.91's not be a good choice?  Wasn't that ratio part of the performance axle package??  I will be running 225/75/R14 radials and F70-14 bias plys for concours shows only.  The radials would be on mostly for cruise nights and non point shows.

[694spdRT]

You will run a lot of rpm on the highway. I would guess that you are looking at 3500 rpm at 55mph. The 3.23's you currently have will run around 2500 at the same speed and 3.55's would be about 3000rpm. Give or take a little on all these numbers but it gives you an idea.

[Ghoste]

Agreed.  I like the deep gears myself but I know they aren't for everyone.  As soon as you start getting into ratios that low you begin to compromise other areas.  Like highway driving.

[resq302]

So I guess if my 3.23's are in good shape, I should leave them in there?  Or should I upgrade to the 3.55's if the ring and pinion need to be replaced?

[firefighter3931]

So I guess if my 3.23's are in good shape, I should leave them in there?  Or should I upgrade to the 3.55's if the ring and pinion need to be replaced?

With a 26in tall tire the 3.55 gear is a good choice. If you were running a 28in tall tire the 3.91 would give you almost the same final drive ratio as the 3.55's w/26in tall tire.


Ron

[Ghoste]

But if the 3:23's are in good shape, you may want to store them in case you want to return to a higher ratio someday.  The 3:23 doesn't seem to be serviced by the aftermarket.

[Just 6T9 CHGR]

Brian with your small diameter tires I would go with a MAX of 3.55's

You will NOT be happy with the 3.91's

Chris, just curious why would the 3.91's not be a good choice? Wasn't that ratio part of the performance axle package?? I will be running 225/75/R14 radials and F70-14 bias plys for concours shows only. The radials would be on mostly for cruise nights and non point shows.

Brian, are we talking "correctness" for the AACA judges (they check gear ratios?) or are we talking driveability?

Yes the 3.91 ratio was offered (A31) but so was the 3.55(A36)

Bottom line, if you actually like to DRIVE your car (this includes highway driving) stick with the 3.55's if you are going to upgrade

Its not fun having to drive 50mph just so your friends with their Super Track Pack 4.10 Dana's dont blow up taching out at 4k RPM @ 70mph

Slight exaggeration but you get the idea

[694spdRT]

Its not fun having to drive 50mph just so your friends with their Super Track Pack 4.10 Dana's dont blow up taching out at 4k RPM @ 70mph

Just run in 2nd and share the pain. 

[Runner]

if you do limited highway driving and the choice was 3.55s or3.91s id go with the 3.91s but if you do much highway driving id go 3.55s.     heck i just droped in a set of 4.10s and i now love taking the car on the highway, 65 is about 3500rpm with a 27 inc h tire.   i hade 4.57s in it before.

   this is one of those different strokes for different folks type deals.   a really nice choice would be a 3.73 you can get those from randys ring and pinion for the 489 housing. id also stray away from richmond gears if it was me.  they are a nice strong gear but tend to make more noise than other gears.

[471_Magnum]

Sounds like you may just have a bad bearing in there. That will make a lot of racket. So will a bad sure-grip.

Gears either whine loudly, or shed teeth when they go.

3.55s are the way to go with 26" tires, although you probably won't notice a huge difference out of the hole. This is particulary true if you're already somewhat traction limited (which you certainly are with the F70-14s).

BTW, while 3.23s aren't available aftermarket, I've seen quite a few NOS sets on Ebay and elsewhere.

[resq302]

Sounds like you may just have a bad bearing in there. That will make a lot of racket. So will a bad sure-grip.

Gears either whine loudly, or shed teeth when they go.

3.55s are the way to go with 26" tires, although you probably won't notice a huge difference out of the hole. This is particulary true if you're already somewhat traction limited (which you certainly are with the F70-14s).

BTW, while 3.23s aren't available aftermarket, I've seen quite a few NOS sets on Ebay and elsewhere.

My problem is that the noise isnt constant.  It is periodic.  Would a bad bearing or sure grip only make a noise occasionally?

Chris, the judges do not check the gear ratio in the car.  AACA rules state the car has to appear how it left the dealership.  3.55 and 3.91 ratios were an available factory option so they are allowed.  Besides, aside from them pulling apart my third member or crawling under to look at the tag on the third member, I highly doubt they would do this.  Mainly I would be changing the gears for performance and driveability.  I do some highway traveling to local shows and cruise night so I don't want to be going through a tank of gas a night cause of the really high rpm's.  Would there be a noticeable difference between the stock 3.23's and the 3.55's?

[Runner]

3.23s are available new from yukon gear

[resq302]

It looks like I will be going with the 3.55's.  Now to decide which brand to get.  Which brand is the better of the brands?  I have heard a lot of people breaking teeth off of the Richmond Gears and another trans shop that I went to with the charger said that the Yukon gears are not as hard of a metal as what the OE ones were.  They recommended Precision Gear.  Has anyone used Precision Gear before?

I am trying to get all the info I can as I am on a very limited budget and my wife gave me the go ahead to get this done once and for all as once Dec. comes, I will have no more time or extra money to work on the charger since my daughter will be born then.  All my time then will go to getting her involved with cars and Mopars!

[471_Magnum]

It looks like I will be going with the 3.55's. Now to decide which brand to get. Which brand is the better of the brands?  I have heard a lot of people breaking teeth off of the Richmond Gears and another trans shop that I went to with the charger said that the Yukon gears are not as hard of a metal as what the OE ones were.  They recommended Precision Gear.  Has anyone used Precision Gear before?

Get whichever brand your builder recommends so that they will stand behind their work.

On a street car with street tires, you can't go wrong with any of the name brands.

BTW, "softer" gears aren't necessarily bad. They endure shock loads better than the "harder" gears. Some suppliers offer a "Pro" gear which is made deliberately softer for this reason. The trade off is long term wear, which on a limited use vehicle like your Charger, is neglegible.

[Runner]

richmonds are a little harder to set up and tend to make more noise, but they are a good strong gear.    do not get a pro gear for a street car. strange/ usgear is really nice street/strip gear and they are a tad more spendy( about 10 bucks a set).   have no personal experiance with yukon or Precision Gear but im sure they are fine and will be  little cheaper sence they are made off shore.    my pick would be us/strange,  but thats me all of them will do a nice job, biut be aware that richmonds can be slightly noisy.

    the one thing that i would definalty add isa a solid pinion spacer, especially with the 4 speed.   it will eliminate the crush sleeve, 35 bucks well spent! would also make changing a yoke or a pinion seal much easier if the need should ever arise.    good luck with your project!

[firefighter3931]

Brian, i agree with Runner on the solid spacer for the 489 center....get one. Ratech sells them for around $30.00.

The other thing worth mentioning is your rear yoke. It must be compatible with the splines on your new pinion shaft. Basicly, there are 2 different spline counts so you need to know which one you have now so that you can order the correct ring and pinion. The splines are either 10 or 29. You can tell which one you've got w/o having to disassemble the centersection.

Here's how :

If the pinion nut takes a 1 1/8 socket it is a 10 spline pinion

If the pinion nut takes a 1 1/4 or 1 5/16 socket it is a 29 spline pinion


So, if you're ordering the new gears before pulling/disassembling the pig.....get a socket on the pinion nut and find out how many splines your rear yoke has. Then you can order up the correct gears for that yoke.



Ron

[resq302]

Ron,

Thanks for the tip.  I have never heard of Strange gears before.  Of course, I am new to this whole rear axle/third member thing too as I thought i would have had it resolved last year with the rebuild.  Precision gear says their gear sets are harder than Yukons but they could also be telling me that just to make a sale.  I am certainly going with the Timken bearing kit cause I have had good luck with Timken bearings before.

overall, I am looking for something that is well made, reliable, is good for driving (hence the decision for the 3.55), something that can take some mild abuse when I feel like dropping the hammer after the break in period is done, and over all, something that will last the life of the car.  Again, money is an issue, but I want to be able to get the best part I can with the money I have.  Even if it means spending a little more now to save me money later down the road.

I really appreciate everyones input with this as this is all new to me.

[Just 6T9 CHGR]

You know for a little more coin, Randy's Ring & Pinion sells complete NEW 3rd members.....well maybe not a LITTLE more....

Wifey might have a preemie if you tell her how much!

[resq302]

Ive already checked into that option.  Slightly out of my price range.  $950.  As much as I would like to get it, I think cost effective wise, I would be better off just getting mine rebuilt.

[Runner]

brian,  you would probably enjoy a good conversation on the phone with this guy http://members.aol.com/doctordiff/   his name is cass and you will  look long and hard to find a more knowledgeable  guy. his prices are acually as cheep as the big mail order places and he sells several different brands. he will give you hjonest answers to your questions. 

    for instance when i ordered my axles from him he told me i should get dutchmans for a street/strip car and strange for a full drag car. he then ordered them a little longer than stock and advised me to remove my ceter button for better spline engagment.

   he also will sell you bearing kits, the spacer ( his is a really nice billet piece) for about the same price mabe cheaper.    imho Cass is the man when it comes to rearends!

[firefighter3931]

brian,  you would probably enjoy a good conversation on the phone with this guy http://members.aol.com/doctordiff/   his name is cass and you will  look long and hard to find a more knowledgeable  guy. his prices are acually as cheep as the big mail order places and he sells several different brands. he will give you hjonest answers to your questions. 

imho Cass is the man when it comes to rearends!

The Dana 60 under my 68 was built by Cass.  Had it shipped all the way from Montana to Vermont 




Ron

[resq302]

Ron,

Thanks for the tip again.  I just removed my driveshaft to get to the pinion yoke nut.  Great news!  It is a 1 1/4" nut.  After talking to Cass (DoctorDiff), he said the 29 spline is stronger than the 10 spline, although the 10 spline was stock in 1969 and 1970.  Later years went to the 29 spline for some reason.  Cass is a really down to earth guy and certainly helped me out a ton.  If it wasn't for the fact it would cost over $50 to ship my third member each way, he would be doing my set up.  And his prices are just as good too.  Definitely a good guy alert for him!

[firefighter3931]

You're welcome Brian. A little detective work saves a bunch of headaches...trust me, i know !  The pinion nut trick is something i learned about...after makeing the assumption that the centersection i was working on was a 29 spline when in fact i had a 10 spline. I am now the proud owner of an MP 29 spline yoke that i can't use  ....oh well on the shelf it sits 


The good news for you is that most of the vendors carry the more popular 29 spline ring and pinion gearsets. I believe Richmond is the only manufacturer of the 10 spline gearsets. Should make it easier for you to get a descent product at a good price. 


Cass is indeed a great guy to deal with. He has a lot of satisfied customers on many of the boards. 



Ron



Ps. Thanks to Runner (Mike) for posting the contact info 

[resq302]

Yes, Mike (Runner) a  on me.  Definitely worth the phone call.  Actually, Cass might be getting my rear to rebuild as the one local trans shop wants $87.25/hr to set up the diff.  They figure it will take about 2 1/2 to 3 hrs to do.  I have to wait and call the other trans shop on Monday as the owner was gone for the day and they couldn't give out their hourly rate.  Even with about $50 shipping each way, Cass might be the one getting my diff.

[Runner]

brian,  if the price ends up with in a few bucks id go with cass. unless you feel really good about the shop doing the work. i know of 2 "rearend shops" here locally that ive seen some down right terrible work come out of. one was a 9 inch center going behind a mid 9 second 500+ cubic inch bb ford. my friend noticed that there wasnt much thread engagement on the yoke nut so he took it to my/our friend that does all of our machine work and he redid everything for him. but im sure if the shop has a good reputation they can do it right. good luck in whatever you decide!


    im a cheap basturd and hate to pay people to do this kind of work so i do it myself ( i also tend to be a glutten for punishment.

[resq302]

My only question and concern is how I will be able to ship it and the chances of it getting damaged in transit.  I'd hate like hell to send it to Cass and have a stellar job done on it only to have the damaged or something broken in shipping.