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Discussion Starter · #1 · (Edited)
Finally got around to upgrading the rear end of my '95 and thought Id share my experience with anyone who's on the fence about upgrading their gears. Hopefully this helps someone.

A few year back I installed a 3200 stall Yank converter (there's a thread floating around somewhere about that) and I was toying around with the idea of running a lower gear. As much as I loved the extra torque manipulation the higher stall added, I still thought my '95 was just "missing" something on the low end...

These cars (compared to the Fbody's and Vettes I'm used to owning) - just feel sluggish around town. These are heavy cars and you really notice that with the factory 3.08 gear. While they may be great for cruising on the freeway at a low RPM, the 3.08 leaves a LOT to be desired in every other aspect of the cars performance.

Unfortunately, the higher stall of the Yank converter didn't help the sluggishness at all.

Sure, it ripped out of the whole at wide open throttle, but if I wasn't flooring it off the line - the converter was basically invisible in normal, everyday driving. That's not entirely a bad thing mind you - but it didn't solve the lazy feel around town or under light-throttle conditions...

That summer, totally by chance, a buddy of mine went to go look at a beat-up '94 Impala with the intention of using it as a parts car. After talking with the seller, we found out he'd previously installed 3.73's. It was a perfect opportunity for me to get a chance to drive one of these car's and see for myself how they felt with the lower gear.

Long story short, it took all of about 2 minutes of driving that old, beat up Impala to realize that a 3.73 ratio is an absolute MUST for these cars. I could not believe how big a difference it made and as soon as I got home that night after driving the car - I started piecing together everything I needed for the swap...



The following is the list of upgrades I ordered from various on-line vendors:

- AAM 3.73 ring and pinion (pretty sure they were the OEM supplier for GM gear sets)

- Eaton Tru-Trak LSD

- Moser 30 spline axles

- ARP 2.5" studs

- Master overhaul rear-end kit

- 3.73 ABS reluctor

- Trickflow HD differential cover

- Inland Empire 3.5" driveshaft with an upgraded forged Pinion Yoke

- Upgraded 1350 U-joints

- and whatever other miscellanious parts necessary for the install including PCM tuning...

I figured while I was in there, may as well upgrade what I could. Not all of the above is necessary if you're just looking for a straight gear swap and nothing more...


Pictures:


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Discussion Starter · #3 · (Edited)
194898

194899



The installation went smooth with the exception of one thing. Turns out, the ABS reluctor wheel didn't fit the pinion. It was the correct reluctor, but for some reason, the I.D. of the reluctor was off a few thousands too large. In a nut shell, it couldn't be "press-fit" on, because it was loose.

A call to the vendor confirmed my suspicions. Apparently, there was a "bad batch" of these ABS reluctors which were not machined properly. Since the car was on the hoist and no replacement could be had anytime soon, it was decided just to finish the install and drive it until I could get a replacement ABS reluctor. Sure enough, the ABS light came on as soon as I hit about 60 km/h.


I ended up ordering a replacement ABS ring directly from the supplier and it arrived about 3 weeks later. Worked out in the end, since I was able to break-in the new gear set in the meantime and change the fluid out again when the new ABS ring was installed.

All was well after that. No more ABS light.

Just something to watch out for if any of you decide to do the upgrade. Double check your new ABS ring and make sure its not part of the same bad batch of rings I was unfortunate enough to receive.




Driving Impressions:

Wow.

It's been said many times on the forum before and I'll say it again. 3.73's should have (at the very least) been an option on these cars if not mandatory. It's a totally different car. In my opinion, it's the equivalent of dropping about 800lbs of vehicle weight. The car's just so much more responsive now. Not only around town, but on the freeway as well. Instant throttle response. Instant take off.

Yes, it rev's a couple hundred rpm more on the freeway. How much exactly, I don't know since it's a '95 - but whatever it is, the small increase in engine speed is not enough to be concerning or annoying.

Mind you, with a 26" tall tire, (285/40/17) the effective gear ratio is actually closer to a 3.90 gear and it's not a problem at all. Wouldn't think twice about driving everyday on the highway - which I do. Stock tire height would reduce rpm even further...

Unlike the stall upgrade which was/is only visible at wide open throttle from a standstill - the gears are always working, regardless of speed or throttle position. The extra torque is always there and can always be felt.

I could not recommend this upgrade enough. Definitely worth the time and money spent.

Acceleration improved more than with all my other bolt-ons combined (including the stall). If anyone's thought about going 3.73, do it. You wont get this kind of a jump in performance with anything short of a heads/cam upgrade (or nitrous)...

And millage? Just filled the car up this afternoon for the first time since the gear swap and I'm very pleased.

My average has always been a rock solid 440-460 km (about 270-285 miles) per tank with the factory 3.08. This is made up of mixed town/highway driving in a very busy (read: heavy traffic) city.

My millage today after the 3.73 swap?

438 km (about 270 miles) - Basically, the loss is so minor, it's not even worth worrying about.


When I get the chance, I'll snap off some pictures of the cars underside so you can see the new shaft and differential cover.


In short, I highly recommend 3.73's on these big old boats. :)

194901
 
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Nice setup ! Im going with 373 gears on my 96 soon as well. I’m from Ontario too , where did you order the parts from ?
 

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Discussion Starter · #5 ·
Ring and Pinion/ABS Reluctor/Tru-Trak Posi/Master Overhaul kit -

Inland Empire 3.5"Custom Length Driveshaft with upgraded slip joint and 1350 ujoints (Have to call and speak to them directly -
** If you don't want/need 1350 Ujoints and a forged slip joint they have two Impala SS driveshafts available "off the shelf" - standard length and extended for longer control arms) - Part numbers IC 94-96C (stock length) + IC 94-96D (extended length) **


Moser Axles -

ARP Wheel Studs -

TrickFlow Differentia Cover -

Valvoline Gear Oil (specified for clutchless LSD units like the Eaton Tru-Trac) -

When I ordered a replacement ABS Reluctor wheel to replace the improperly machined original I received from Clear Image,, I ordered it here - Hope that helps :)


Hope this helps
 
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