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95 Roadmaster, PCM and other questions.

Tri Shield

New member
2
0
1
Buick Ownership
1995 Buick Roadmaster
Hi!

I just bought a 95 Buick Roadmaster sedan, base model. It's a model I've had my eye on since they were new and I've finally gotten a hold of one. Gold on gold., leather interior, 56,000 miles. Not in bad shape, going to be my daily driver, but I've got some plans to spruce it up a little.

Mainly I'm looking at adding a rear-sway bar, posi-rear end, and 3.08 gears.

I've been doing some research on what I need to get the rear end swapped out and a local shop in town can do it. My main question is what is the easiest/cheapest way to reprogram the PCM so that the speedometer reads correctly?

I'm not going to worry about modding the engine for more power, just want to enjoy it as it is with the changes I've outlined for driveability.

Thanks!
 

torres7

Full Member
105
5
18
Lincoln Nebraska
Buick Ownership
Buick RMW
What gears do you have right now? Did you check the code tag to confirm you don't have a posi rear end from factory? I believed the sedans had a rear sway bar and posi from factory, at least if you have a tow package, but I could be wrong. I have a 96 wagon with the tow package but it doesn't have a rear sway bar for some reason. If you have a shop do the rear end they should know how to adjust the speedo, otherwise just compare it to the gps speed on your phone and see how far off it is after the gear ratio is changed and adjust your speed accordingly. Depends on your current gearing and how much it's gonna change, sometimes it's not too far off.
 

Tri Shield

New member
2
0
1
Buick Ownership
1995 Buick Roadmaster
The option tag lists "GM8" which translates as: AXLE,REAR,2.56 RATIO.

No sway bar, but it does have the mounting holes on the lower control arms.
 

torres7

Full Member
105
5
18
Lincoln Nebraska
Buick Ownership
Buick RMW
Yeah, you have really high gears, jumping from 2:56 to 3:08 is probably gonna freak out your speedo quite a bit but it depends on what size tires you're running too I guess. Sway bar should be really simple to install. So you don't have the G80 code after the GM8 uh? That sucks. Mine has 2:93 gears with a posi and I like it that way since I do mostly highway driving and then gravel roads. I like the fuel mileage and still has the "giddy up" when I hit the gas.
______________________________
 

Dirtybob

Junior Member
96
19
8
Buick Ownership
95 RMS

torres7

Full Member
105
5
18
Lincoln Nebraska
Buick Ownership
Buick RMW
I remember trying to install a sway bar in my older wagon out of an Impala or Roadmaster sedan, (can't remember) but I remember the wheel base is different from the sedans to the wagons, so sway bar from sedan won't fit wagon. It was about 2" too short. It was a nice experience.
 
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