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2.29 or 3.23 posi

4K views 14 replies 8 participants last post by  Lvrnespeca 
#1 ·
Hey all, I am looking to buy a posi rear to replace the 4.10 rear in my Elcamino. I have found 2 of them near by, one is a 2.29 posi and the other is a 3.23 posi.

I am not sure which one to purchase, my future plans include swapping the th200 3 speed for a 200-4r overdrive.

I have seen pictures of the 2.29 posi, it looks decent, and is said to have upgraded axle shafts from Moser, as well as new lines and brakes, for $400.

The 3.23, I am still waiting to hear about, is said to have new brakes, for $350.

Anyone have any input on the difference between the 2 as far as mileage, and performance?
 
#2 ·
Sounds like these are, whole rear end swaps, which is a good thing. My concern would be the change from 4.10 to 2.29, even with the trans change to the 2004R, this will be a huge difference. If all things are equal, the 3.23 will be less of a shock.
 
#3 ·
Hey. The 2 series will work for gears from 3.08 and down, The 3 series is for 3.23 gears and up.If a over drive is in your future I would go with the 3.23 posi because your 4.10 will also fit this carrier.Any thing lower then a 3.08 and you wont need a over drive. Doug
 
#4 ·
It'll be a dramatic drop off, it'll feel like your engine isn't running right, down on Power bc of the gear difference. If I was going to run an OD tranny 3.42 would probably be my lowest gear choice
 
G
#5 ·
Trust me, you don't want a 2:29 ratio with an overdrive trans. I have a very mild cam in mine and even at 45-50 the car would still lurch from cam lope. Personally I like my 3:73 but your best bet is the 3:23 or slightly higher ratios.
 
#6 · (Edited)
I agree with the comments above and would suggest you definitely pass on the 2:29 rear end ratio even if a 220R4 with the overdrive is contemplated or not . For 17 years I drove an 83 with the factory stock 305 cu. in. engine , 200R4 and a 2:41 ratio . No get up and go from a stop as it would squat some if you nailed it . Most of Florida is flat but even then , sometimes the computer would send a check engine light signal and run rough . If I pulled over and restarted the engine it would go away . The engine with that 2:41 and overdrive trans would start lugging every now and then which is not good . For most owners the 2:41 may be a good mileage choice but you don`t have much performance if that is what you desire . The lugging would also happen with my current 87 with a mild 350 cu. in , a 200R4 and 2:41 ratio . I then installed a Tremec TKO 500 , 5 speed and it still did the same as the 5 speed as it has a .81 overdrive similar to the 200R4 . After 464 Elky installed a 3:42 posi for me last year those problems totall disappeared . I now have decent take off power , good highway cruising RPM`s , no lugging , decent gas mileage as the engine runs at the right RPM`s to support my air conditioner and other systems . Hey , it evens sounds better . There are other forums that discuss the ideal RPM ratios that might help you decide and some other more knowledgeable members might comment for you . This is my opinion based on my personal experience but after 464`s work I could not be happier with my combo .
 
#7 ·
I would like to go with the 3.23 posi, because it is closer to where I live, and not as expensive. Now, if only the person selling it would call or email me......
 
#8 ·
Keep your 4.11 rearend. when you go to the overdrive it will be nice to have to throw back in. im running 3.73 and am seriously debating going the 4.11 route with my overdrive.

at the moment 80 mph is a bit under 2500 rpm. with 3.40 gears and an overdrive 80mph was about 2100 rpm and lugs the motor a bit on the interstate. i couldnt imagine anything lower, 3.23 even would be insane.

unless you plan on the car doing over 140 mph youde never need to shift the overdrive out of 3rd if you paired it up with tall gears.

think of it this way:

3.40 is the magic number. anything taller ( 3.23, 3.08 etc) is a 3 speed trans ratio.
anything lower, (3.73, 4.11 etc) is good for an overdrive.
 
#9 ·
The plans for the overdrive are not in stone as of now, just something i am considering.

So, at this point I am looking to swap out the 4.10 so I can drive it with the 3 speed.
 
#10 ·
then id still go with the 3.23... youll sacrifice some acceleration but not all of it.
 
#11 ·
yup, I talked to a guy that I go to church with, who has done a lot with cars, and he also suggested to pass on the 2.29 posi.

I really want the 3.23 posi, but the guy who is selling it hasnt gotten back to me yet.
 
#12 ·
Well, after talking with a friend that lives in the area, who has done a lot with building cars, we decided to pass on the 2.29 posi.

However, the guy with the 3.23 posi finally called me, I went over yesterday (Monday), looked it over, and put a deposit on it and will pick it up on Friday. :nanawrench:
I could not find where the axle code was stamped, to verify for sure, but we counted the turns of the pinion to the axle shaft, and it came to about 3 1/4, so i am pretty sure it is a 3.23.
 
#14 ·
Well, since recovering my build sheet, I have found that my Elky had originally came with an open 2.41 rear.

I am not sure if that is the rear end that was in it when I bought it, but that is what it left the factory with.
 
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