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  • 3.89 gears, are my findings correct?

  • Speed Sensors and ATF+4 and the like
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Speed Sensors and ATF+4 and the like

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 #321046  by seajai
 November 10th, 2013, 6:59 pm
Ok, I've been reading up on the 3.66 to 3.89 gear ratio swap. I was under the impression that changing the ring and pinion was necessary to get the 3.89 ratio, but after some reading, it looks like I can just swap the transfer chain and sprockets from the 32/33combo to the 31/34combo. Is this correct? Factorychryslerparts.com lists 2 different ratios and p/n#'s for a ring and pinion set (04567617 and 04539755) but the 03 LH parts book only has 1 p/n listed (04567617). A sprocket swap would be much easier than a R&P swap.

Being that 300M Specials aren't all that common, it looks like the best place to find the 31/34 sprocket combo is out of a 42le mated to the 2.7l engine. Is there another source I'm missing?

Can the PCM be reprogrammed using the DRBIII to the new gear ratio so I don't have to track down a special PCM?
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 #321048  by FIREM
 November 10th, 2013, 7:51 pm
Yes sprocket swap is all thet is needed, not the ring & pinion gears. DRBII can be used to reset so the speedo will be correct. 2.7 trans will provide the pars needed and or a set out of a "Special" trans. (I may have a "Special gear set in my parts bin)
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 #321050  by Bill Putney
 November 10th, 2013, 8:05 pm
FWIW, the same chain can be used with either set of sprockets.
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 #321056  by seajai
 November 10th, 2013, 8:32 pm
FIREM wrote:Yes sprocket swap is all thet is needed, not the ring & pinion gears. DRBII can be used to reset so the speedo will be correct. 2.7 trans will provide the pars needed and or a set out of a "Special" trans. (I may have a "Special gear set in my parts bin)

How much would one have to give for said gears?
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 #321082  by FIREM
 November 11th, 2013, 7:46 am
$ 60 plus shipping is the going price these days..
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 #321190  by paintballdude05
 November 12th, 2013, 9:46 pm
The DRB won't be able to change the gear setting in the PCM. You will need to swap in a 300M Special PCM to make it all work correctly.
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 #321191  by 300maximilien
 November 12th, 2013, 10:19 pm
I have the gears, special pcm and pretty much anything else you might need/want
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 #321192  by Maximus
 November 12th, 2013, 10:26 pm
Ha Craig's cutting in on Bobs turf ha just kidding... :P
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 #321207  by seajai
 November 13th, 2013, 8:23 am
paintballdude05 wrote:The DRB won't be able to change the gear setting in the PCM. You will need to swap in a 300M Special PCM to make it all work correctly.
If I swap the PCM, won't I need to do the SKIM, BCM, and cluster too so it will work? Or is just a matter of reprogramming it with my existing vin#?
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 #321210  by Strmvt
 November 13th, 2013, 9:30 am
seajai wrote:
paintballdude05 wrote:The DRB won't be able to change the gear setting in the PCM. You will need to swap in a 300M Special PCM to make it all work correctly.
If I swap the PCM, won't I need to do the SKIM, BCM, and cluster too so it will work? Or is just a matter of reprogramming it with my existing vin#?
Technically yes however if you can find a friendly dealer that will reprogram your pcm with your vin
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 #321211  by seajai
 November 13th, 2013, 10:01 am
Strmvt wrote: Technically yes however if you can find a friendly dealer that will reprogram your pcm with your vin
OK, cool. I had a guy buy some 300m parts from me this spring that works at a Chrysler dealer, I'll have to give him a call. Do they need to pull the vin from my computer first before programming it into the special PCM, or do they just punch in my existing vin in to the DRB and then put it in the special PCM?
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 #321214  by 300maximilien
 November 13th, 2013, 10:11 am
TO reprogram you will need your VIN and the PIN AFAIK.

If you buy all the matching parts you WILL NOT need reprogramming/DRBIII

I even have 3 sets of keys/fobs and the key cylinder.

I guess I should list this stuff in the BST soon
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 #321226  by seajai
 November 13th, 2013, 3:06 pm
PIN?
AFAIK?

Haven't heard these ones before.
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 #321227  by 300maximilien
 November 13th, 2013, 3:17 pm
PIN is the code needed to get into the PCM

AFAIK = as far as i know
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 #321248  by paintballdude05
 November 13th, 2013, 9:00 pm
What Craig said. You either buy a Special PCM and get the dealer to program it to your existing system or buy a "combo" and avoid the dealer.