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Considering switching from 3.05 to 3.29 gears.

R

Roofus

New member
As the title states I'm seriously considering switching from my stock 3.05 Diff to the 3.29 diff.

I've got a few mods on N/A Series III that have pushed my peak torque up so high in the RPM range I'm dead in the water until I hit 3.5-4k. I can't even get spin when launching anymore.

I have ER Rockers which by themselves are advertised to move peak WHP from 5k to 5.7k, HV3 Insert, Wizaired CAI and both front and rear ZZP powerlogs. Before powerlogs I was at a 7.5-7.7 0-60. Now I'm looking at 8secs on a nice cool day and closer to 9 at 80-90 degress ambient temp.

I was wondering how much of an improvement in acceleration I could expect from stepping up from 3.05s to 3.29s.

I'm also going to get a mail order tune for the diff swap and the bolt ons. Probably another 20hp ontop of what I already have.
 


its not the diff, you need to change, its the gears and chain, and its not worth it really. some like them na gears better and install them over the sc tranny gearing.

if your car wont move like it used to or cant spin the wheels any more. sounds like the trannys on its way out.

modding a na car is also not really worth it. unless your top swapping it or going turbo.
 
The 3.05 final drive ratio is the differential planets and Sun Gear on the 04+ ULEV cars. Chainset is 35/35 or 1:1 aka 3.29 fdr with the non Ulev diffs installed (early HD and nonHD)

Its a nice mod
 
That's exactly what I'm hoping. I have yet to locate the ID tag on my transaxle but since It's N/A there's I'm putting my money on the 3.05 gearset. The diff has been confirmed to have the 3.05 ratio, and if you do the math, using any other gear chain set except the 35/35 tooth results in really funky ratios that are not at all common in anything except maybe a minivan or suv with the 4t65e

This was taken from RegalGS.org.

​With 2.86 diff:
Use 35/35 gears to end up with 2.86:1 (my LeSabre is like this)
Use 37/33 gears to end up with 2.55:1 gears
Use 33/37 gears to end up with 3.21:1 gears

With 3.05 diff:
Use 35/35 to end up with 3.05:1
Use 37/33 to end up with 2.72:1
Use 33/37 to end up with 3.42:1 (did this for my Regal)

With 3.29 diff, as we all know:
35/35 gears give 3.29:1 ratio
37/33 gears give 2.93:1
33/37 gears give 3.69:1

And the Series IIIs were the first SULEV compliant vehicles. Most likely 3.05s. In regards to the Tranny going out not possible with the the shape it was in a month ago when I changed the fluid and filter. Not even a full shade darker than the fresh AC Delco DEX VI I put into it. I dropped the pan once at 42k miles and there was tons of metallic sludge from steel and friction disk material which had settled in the pan.

Last month I dropped it at 119k, and despite beating the piss outta the car on a regular basis there was no metallic sludge PERIOD! A fine silt in a few spots on the pan, the top of the filter had a thin film of material and that was it. As stated fluid was in like new condition.
 
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Plans are a go, spent a few hours going over all the RPO codes, I have the 3.05 (F83) M15 (245mm TC). Intense confirmed that all Lacrosse's either came with 3.05 or 2.86 gearsets using the 1:1 drive chain, however the 2.86 diff isn't available on the 2009.

Diff is $100, Tune with shipping more than likely around $450-$500
 
I have found the source of the wheel spin-less launches and it isn't lack of low end grunt. I may have launched a little to hard, I'm noticing a clunk from the passenger side engine compartment when I shift from P to R. Seems to be a broken or loose motor mount.
 


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