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Discussion Starter #1
I have searched. And searched some more. Then I searched again.

I'm an idiot savant rock crawler that's taken a lot of blows to the head and rolled my rigs way to many times in the last 40 years so I could be screwing up my search parameters, but...I still can't find what I'm looking for...Hey, there's a song in that.

I'm doing a complete third member swap. Dropping out the old one and putting in a new (to me) third member. Viewing a write up would be helpful.

I'm not scared. If I can't find the info I'm still going in.

Thanks,

-Scott
 

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Discussion Starter #2
FYI-I have not been able to find a specific to an SE Challenger write up.

I did the swap in my driveway today. It took about 2.5 hours and was a piece of cake. It's worth it.
 

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what year SE did you put the new diff in? What size diff? any problems with driveshafts or halfshafts or hubs?
 

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I have searched. And searched some more. Then I searched again.

I'm an idiot savant rock crawler that's taken a lot of blows to the head and rolled my rigs way to many times in the last 40 years so I could be screwing up my search parameters, but...I still can't find what I'm looking for...Hey, there's a song in that.

I'm doing a complete third member swap. Dropping out the old one and putting in a new (to me) third member. Viewing a write up would be helpful.

I'm not scared. If I can't find the info I'm still going in.


Thanks,

-Scott

Man I wish. There are a few people that have done it, but no one thinks of doing a "how-To", usually. Which is too bad.

When I stick that Inertia Motorsports 4.0L stroker with heads and 1.1 cams in it in my "wife's" Challenger, I promise to do a DIY. lol.
 

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I'd like to get a little more info on this, also. What's the difference between the factory SE differential and the 198? From where is the 198 diff sourced?
 

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The SE's all have 198mm differentials. The gear ratio's are different depending on if you have a 4 speed or 5 speed. Do a search on this forum for gear ratios,there's quite a few theads on it
 

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Oh, I see. He just swapped his factory 198mm diff for a different one with most likely a different gear ratio. I thought he was upgrading the diff with one front an R/T or SRT.
 

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FYI-I have not been able to find a specific to an SE Challenger write up.

I did the swap in my driveway today. It took about 2.5 hours and was a piece of cake. It's worth it.
So did you take pics?
 

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Discussion Starter #10 (Edited)
Hello,

I would have loved to take pics and done a write up but my buggy is in my garage with out a rear axle under it currently so I had to do the swap in the driveway. Which meant doing it quickly and getting it done.

The swap I did was just pulling out a complete stock 2010 third member and replace it with a stock (lower geared) 2009 third member.

Why lower the gearing?

I went from stock 215/65-17 tires to 285/40-20. Which is a change in outside diameter (height) from 28 inches to 29 inches...1 inch taller or 3.6% taller.

The stock rear gear ratio of a 2010 SE with a 5 speed auto is 2.87:1 (sucky). So to get my gearing back to stock I'd need 3.6% lower gearing (0.10332), making my new gear ratio requirement 2.97:1.

Well, since we live in reality...for the most part, there is no such animal as a 2.97:1 ring and pinion for a 198mm Chrystler rear end. The next closest option is a 3.06:1. It would be a good option as it is 6.62% lower the then stock ratio which would help over come the added rolling resistance of the significantly wider tires. That would keep the car pretty close to the stock feel of acceleration and general drivability.

That wasn't really as low as I wanted to go. If I was going to do the swap, I really wanted the added benefit of lower then stock gearing to assist in getting off the line and general acceleration performance increases. So I went with a 3.64:1 ratio which is almost 27% lower then stock.

A gear ratio of 3.64:1 compensates for the increase in tire size and rolling resistance of the wider tires and then some. The reduction almost makes poor low end throttle response a thing of the past because it puts the motor in its power band quicker. It's still there but is masked by the nearly instant thrust into the power band.

Is it worth it?

OH YEAH!!! It's like a whole new car again. After the install, I put 300+ miles on the car that day because it was just to much fun to get out of it.

So...what are the down sides?

Minor fuel mileage decrease on the highway.

I'm not sure exactly how negatively it will impact my highway mileage but it surly will. I've been mashing down on the go button more then normal because it's way fun. In theory it should actually help my city mileage because it takes less effort from the motor to make the car move from a dead stop (as long as you're not romping it all the time). That's what I've found to be true on all the other vehicles I've re-geared after tire size increased.

Data I can report is the RPM's at 70MPH in 5th gear:

2150 RPM's with 215/65-17 tires and 287:1 gearing (stock/stock)
2000 RPM's with 285/40-20 tires and 287:1 gearing
2500 RPM's with 285/40-20 tires and 3.64:1 gearing

To my knowledge, the gearing options for a 198 rear end are:
2.87:1 (5 speed 3.5L Challenger, Charger, Magnum & 300)
3.06:1 (AWD Magnum)
3.64:1 (4 speed 3.5L Challenger, Charger, Magnum & 300)
3.90:1 (2.7L Charger, Magnum & 300)

***Please take the above gearing options as a guide, not as fact. I'm not an expert in what gearing came in what model. It's info I gleaned via on-line searches. Please investigate for yourself before buying a third member.)

-

As a reference, my car is a 2010 base model SE with a 3.5L motor & a 5 speed transmission. The only other "performance" type mod's I've done are the stupid big tires and wheels (245/45-20 tires front on 20X9 wheels & 285/40-20 tires rear on 20X10 wheels) and a complete SRT8 suspension swap. I've also re-tuned the car for 91 pump gas, firmer shift points, the tire size change, raised the allowable top speed and now the gearing change.



Happy motoring.

-Scott
 

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Discussion Starter #11
Here is something that made me and a few of my buddies smile. It's something rarely seen these days. I highlighted it with a silver Sharpie and snapped a pic the night before the install.

 

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Here is something that made me and a few of my buddies smile. It's something rarely seen these days. I highlighted it with a silver Sharpie and snapped a pic the night before the install.


That thing looks familiar. I could swear I've seen one like it before? Glad it's working out. You are lucky to have the 5spd tranny...many more options!!!!
P.S. looks better there than sitting in my garage collecting dust.:pimp:
 

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Hello,

I would have loved to take pics and done a write up but my buggy is in my garage with out a rear axle under it currently so I had to do the swap in the driveway. Which meant doing it quickly and getting it done.

The swap I did was just pulling out a complete stock 2010 third member and replace it with a stock (lower geared) 2009 third member.

Why lower the gearing?

I went from stock 215/65-17 tires to 285/40-20. Which is a change in outside diameter (height) from 28 inches to 29 inches...1 inch taller or 3.6% taller.

The stock rear gear ratio of a 2010 SE with a 5 speed auto is 2.87:1 (sucky). So to get my gearing back to stock I'd need 3.6% lower gearing (0.10332), making my new gear ratio requirement 2.97:1.

Well, since we live in reality...for the most part, there is no such animal as a 2.97:1 ring and pinion for a 198mm Chrystler rear end. The next closest option is a 3.06:1. It would be a good option as it is 6.62% lower the then stock ratio which would help over come the added rolling resistance of the significantly wider tires. That would keep the car pretty close to the stock feel of acceleration and general drivability.

That wasn't really as low as I wanted to go. If I was going to do the swap, I really wanted the added benefit of lower then stock gearing to assist in getting off the line and general acceleration performance increases. So I went with a 3.64:1 ratio which is almost 27% lower then stock.

A gear ratio of 3.64:1 compensates for the increase in tire size and rolling resistance of the wider tires and then some. The reduction almost makes poor low end throttle response a thing of the past because it puts the motor in its power band quicker. It's still there but is masked by the nearly instant thrust into the power band.

Is it worth it?

OH YEAH!!! It's like a whole new car again. After the install, I put 300+ miles on the car that day because it was just to much fun to get out of it.

So...what are the down sides?

Minor fuel mileage decrease on the highway.

I'm not sure exactly how negatively it will impact my highway mileage but it surly will. I've been mashing down on the go button more then normal because it's way fun. In theory it should actually help my city mileage because it takes less effort from the motor to make the car move from a dead stop (as long as you're not romping it all the time). That's what I've found to be true on all the other vehicles I've re-geared after tire size increased.

Data I can report is the RPM's at 70MPH in 5th gear:

2150 RPM's with 215/65-17 tires and 287:1 gearing (stock/stock)
2000 RPM's with 285/40-20 tires and 287:1 gearing
2500 RPM's with 285/40-20 tires and 3.64:1 gearing

To my knowledge, the gearing options for a 198 rear end are:
2.87:1 (5 speed 3.5L Challenger, Charger, Magnum & 300)
3.06:1 (AWD Magnum)
3.64:1 (4 speed 3.5L Challenger, Charger, Magnum & 300)
3.90:1 (2.7L Charger, Magnum & 300)

***Please take the above gearing options as a guide, not as fact. I'm not an expert in what gearing came in what model. It's info I gleaned via on-line searches. Please investigate for yourself before buying a third member.)

-

As a reference, my car is a 2010 base model SE with a 3.5L motor & a 5 speed transmission. The only other "performance" type mod's I've done are the stupid big tires and wheels (245/45-20 tires front on 20X9 wheels & 285/40-20 tires rear on 20X10 wheels) and a complete SRT8 suspension swap. I've also re-tuned the car for 91 pump gas, firmer shift points, the tire size change, raised the allowable top speed and now the gearing change.


Great additional info to what's already on the site. wow, 2.5hours hey?

With larger wheels tires, I think that's the way to go. It's one of the reasons I think they stick the 3.92's in the Chrome Clad options R/Ts. I wonder how heavy those wheels/tires are?

I think if you are sticking with the stock 17's or 18's, the 3.06 would be pretty decent. Going with a set of heavy aftermarket 20's and some serious rubber, 3.64 sounds like the way to go. I'd think 3.90 would be a bit big, but gearing can also be a bit of a personal thing.
 

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Discussion Starter #14
I wrote a basic write up in a PM but thought it may be useful to anyone thinking of doing the swap.

Please use caution and know how to lift your vehicle before you begin. I'm not going into the safety speech, but if you don't know how or have the proper equipment to get your vehicle off the ground and re-weight it, stop. Don't even begin the swap yourself.

-use 2 drive on ramps to lift the front of the vehicle
-use 2 jacks to lift the rear of the vehicle and place 2 jack stands under the rear of the vehicle
-weight the rear of the vehicle on the jack stands
-remove the tires/wheels
-remove the exhaust
-put the car in neutral
-remove the drive shaft from the yoke
-support the drive shaft
-drain the oil (9/16 or 14mm Allen)
-with a jack, weight the rear suspension so the shafts are at ride height
-put jack stands under the rear control arms to hold the weight
-pop the 1/2 shafts loose
-brace the 3rd with a jack
-remove the front bolt on the 3rd
-use 2 13/16 shallow sockets to remove the 2 rear bolts (the suckiest part)
-lower the 3rd enough to work the 1/2 shafts out
-drop out the 3rd
-loosen the fill oil fill plug of the new 3rd
-put thread locker in the 2 rear holes of the new 3rd
-lift the new 3rd into place
-install the 1/2 shafts all the way into the 3rd
-make sure the pinion is pointing close to the angle it lives and add new gear oil
-jack the 3rd into place
-tighten the 2 rear bolts (the 2nd suckiest part)
-mate the drive shaft to the yoke and hold loosely in place with at least 1 bolt
-lift the front of the 3rd into place and reinstall the front bolt and bushing
-add thread locker to the drive shaft bolts and reinstall all 3
-reinstall and align the exhaust
-remove the jack stands from the lower control arms
-reinstall the tires/wheels
-lower the rear to the ground
-torque the lug nuts
-drive around with a big smile on your face

Hope this helps.

-Scott
 

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Discussion Starter #15
Some interesting MGP data to report post re-gear.

28 mpg - Bone stock (about 500 miles logged):browsmiley:
28 mpg - stock/dual exhaust (about 1500 miles logged):eek:hyeah:
26 mpg - stock/trans tweek/dual exhaust/89 tune (about 500 miles logged):naughty:
21 mpg - 285/40-20 rear tires/stock gearing/dual exhaust/trans tweek/89 tune (about 2000 miles logged):banger:
20 mpg - 285/40-20 rear tires/stock gearing/dual exhaust/trans tweek/91 tune (about 5500 miles logged):bang:
22 mpg - 285/40-20 rear tires/3.64:1 gearing/dual exhaust/trans tweek/91 tune (about 600 miles logged):bigthumb:


*all a mix of city/highway and moderate to semi-agressive driving style :toomuchinfo:
 

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Wow, the addition of that wheel and tire combo sure killed your fuel economy!
 

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Wow, the addition of that wheel and tire combo sure killed your fuel economy!
Temps might have played a roll as well, but yeah, big heavy meats are not the friend of the V6. They are however, a friend of the exterior of the Challenger :bigthumb:
 

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I'm totally doing this when I can locate a 3.64. I'm getting a bit over 20mpg now, so i don't really look at it anymore. I just put 20" chromers so I think it finally something to feel a bit more power. Maybe i'll throw in a TC while im at it. Now off to find a second jack!
 

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I've had 3.64 gears in my 2010 SE for 1 1/2 yrs now. Still run the stock 18" Rallye wheels and tires. I get 24.5 to 25.5 mpg with the cruise set at 70mph and air on. I did not see a huge drop mpg with the gear change.

The gear swap is one of the best mods you can for the SE.
 

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