Changing gears for rearend

[ChargerSG]

I have 4.10s in 8.75 rearend(suregrip) with Detroit locker center section, manual valve body with B&M 'Hammer Shifter' but this setup isent nice mpg on, fun but hell for my wallet Now im thinking in chaning the gears to 8.25 or 8.75 to get a better mpg(and i go for shows far away all the time) So is it hard to change gears, and what kind of cost is there?

Now to something completly diffrent In the winter im planning in chaning the 383 Magnum for a 440 Magnum(swap engines between the Challenger and the 69 Charger) but can the tranny stand a 450-475hp 440 Magnum?

[Chatt69chgr]

I think what you are wanting to do is change the rear end ratio from 4.10 down to something more reasonable for highway use.  That would probably be a 3.23 or 3.55.  Maybe a 3.73.  Check the Strange Engineering website.  They had the best deal that I found and their gears are made in the good old USA.  As far as changing them, you would probably be best off to get the gears and other parts and take them to someone that specializes in this.  They will have all the equipment to install them and if this isn't done correctly, the nice ring and pinion you bought won't last too long. 

Someone else will have to answer the automatic transmission question but 727's are pretty strong.  I doubt you would have a problem at this hp level.

[ChargerSG]

Thanks for the info I wont be changing them myself since i know nothing about it

[John_Kunkel]

If you can afford it, it would be nice to keep the 4.10 intact and just buy another 3rd member with 3.23 gears, that way you can swap them as the mood arises.

Only takes about a half-hour to swap pumpkins.

[ChargerSG]

I have been tempted to do that but its a money issue(as allways)

[is_it_EVER_done?]

Since the 4.10 8-3/4 center sections are allways in demand, I bet you could trade it straight across for a 3.23 or 3.55 sure grip center section (in good shape).

I traded a 4.30 center section for two 3.23 posi centers. As I love the 3.23's because I drive many thousands of miles per year, I was a happy camper!

[firefighter3931]

Keep the 4.10 centersection intact and buy another pumpkin with open gears.....you don't need a suregrip to travel to shows. The open (non suregrip) centersections go for cheap....i passed on a 3.91 open unit this past w/e for $125.00

The cost of new gears and installation will far exceed a used open 3rd memeber.....and you will have both. 

Trust me, you're gonna miss those 4.10's if you replace them with 3.23's.....they will be going back in for around town fun ! 



Ron

[deputycrawford]

Fire fighter is on the money again. I have a 4:10 489 case rear. I had a 3:23 sure grip rear until my soon to be ex-wife gave it away. I will buy another because 30 mins to change a rear end once a year is worth the money to own both. You will mis the 4:10 and end up spending the extra to buy another 4:10 later.

[tecmopar]

This is why the 8 3/4 rear is so neat, not to many other rears that you can do a gear change in a 1/2 hour and sure-grip or not their pretty strong and trouble free. Hang on to that 4:10 pumpkin and find yourself a 3:23, you won't regret it, good luck.

[T16]

Planning on changing my rearend from 2.76 --> 3.23.. will I notice a big difference..? Maybe a new converter too
Engine: 383 + .060, Crower 271, Holley SD..

[Hot_Rodder]

ChargerSG.... If you want to swap out the third members, and keep the 4.10 SG unit, then give me a hollar. My '69 that I had had an open 3.23 setup. I, somehow, messed the carrier up, but only that. The 3.23 gears seem to be fine, and the housing is fine, it's a 489 case. The only thing that would need to be done is change the carrier. If you decided on this, you could either get a used open carrier real cheap if you wanted, of get a SG unit new or used also. Anyway, I've not set a price on it, but it's just sitting around in a basement, and I need to move it, and everything else to get it out of the way, so let me know. I can also take closeup pic's of it, and send them to you if you want.

[Steve P.]

Save some money and have the best of both worlds.. Add a overdrive unit. At the flip of a switch you will be in overdrive and cruising the highway at much lower RPM's...

It is a fairly quick change out if you have both pigs.  I just figure that for light to light action I  want the 4.10's. Once I get cruising I want to flip that switch and bring down the R's...

[Hot_Rodder]

I agree, the Gear Vendors overdrive unit is nice, thinking about trying to get one a little bit later on because at over $2k... I got a few other things that need to be done first....

[ChargerSG]

Now to the next thing, how do i see if its a 489 case or not?

[Steve P.]

The part numbers are cast into the drivers side bottom of the pig. The last 3 numbers will be your reference.

[ChargerSG]

Thanks