Thread: Bandook's 01 Imp, top swap-ified

I'm not 100% sure what the impala came with, would have to see the code on the trans to figure out, but you will need the output shaft regardless to run the hd diff. If you've already done the research and figured out what your ratio will be, then disregard what I said about that. OS isn't too hard to grab.

Turns out my squeak was coming from the bearing, not the axle. Yeah, no one ever accused me of being good at diagnosing things. I've done probably 5-6 wheel bearings, but never heard one squeak like this. I SWORE it sounded like it was coming from the inner boot on the axle. But, yeah...the back of the hub is a Rusty mess.

But...I'm still not getting my head around the final drive. This is what I read:

Non-HD transmissions come with several different differential ratios, none heavy duty size, and since most of them use 35/35 or 1:1 gearsets already, you cannot purchase 3.29 gearsets to alter the final drive since they're what you already have. To change the gear ratio, you'll need to swap the diff, and since they're easy to swap you may find you want to look at a swap to improve performance or reversely fuel mileage.
97-03 Grand Prix natural 3800s also use a 3.29 differential and 35/35 gears
04-08 Grand Prix natural 3800s use a 3.05 differential and 35/35 gears
05-09 Allure/LaCrosse 3800s use a 2.86 or 3.05 differential depending on year and 35/35 gears
00-05 Impala 3800s use a 3.05 differential except for some sport packages that use 3.29 and 35/35 gears
00-05 Monte Carlo 3800s use a 3.29 differential and 35/35 gears
00-05 Monte or Impala 3400s use a 2.86 differential and 35/35 gears
06-11 Impala or Monte Carlo 3500s use a 2.86 differential and 35/35 gears
06-11 Impala or Monte Carlo 3900s use a 3.29 differential and 35/35 gears
05+ Buick Allure/LaCrosse CXS with the Cadillac 3.6 Alloytec use a 3.29 differential and 33/37 gears for a final drive 3.69 ratio
As you can see from above, vehicles that have a 2.86 differential such as the 06+ Impala 3500s could benefit in acceleration from a 3.29 differential swap, for example, from an 00-05 Monte 3800, 97-03 Grand Prix or 06+ 3900 Impala. Overall I find the 3.29 gearing the best feeling and best performing, and its worth the swap in either way you need to perform it.

So this is bogus information? It's from Overkill Motorsports. Found here.

Have an ATSG manual for the transmission? It has the info broken down by the 4 digit codes of the transmission. PM me if you want a manual.

Originally Posted by bandook

Turns out my squeak was coming from the bearing, not the axle. Yeah, no one ever accused me of being good at diagnosing things. I've done probably 5-6 wheel bearings, but never heard one squeak like this. I SWORE it sounded like it was coming from the inner boot on the axle. But, yeah...the back of the hub is a Rusty mess.

But...I'm still not getting my head around the final drive. This is what I read:


So this is bogus information? It's from Overkill Motorsports. Found here.

ok here i go. this is what i understand about the transaxle ratios: the ring and pinion is what most of us are familiar with giving us our final drive ratio on rear wheel drive vehicle with the driveshaft in between the rear axle and the transmission.

in our transaxles in lieu of a drive shaft there is a chain to transfer the energy to the differential. if the teeth on this chain drive setup are a 1 to 1 ratio the final drive = the differential ratio we are all used to. however, if we change the gear tooth count on the chain going to the diff, we create more mechanical advantage thus adding more final drive ratio.

that's what was confusing for me at first- a "3.29" diff isn't a "3.29" final drive? yep. if those teeth on the chain that drive the diff are not a 1:1 then yes.

hope that clears things up. that's how i understand these things at the moment. someone that has had one of these transaxles apart or more experience with them please chime in to help if i'm wrong.

Yes, and the HD tranny has 37 drive/33 driven gears. Which gives it a 1.21:1 ratio. It has a 3.29 diff which makes the final drive 2.93.

My car has a 1:1 ratio drive/driven gearset and a 3.05 diff. What the article I posted implies is that I can put a non HD 3.29 diff, which has a 44 tooth sun gear, and get a 3.29 final drive. I'd like to know if Overkill is wrong, which is what I'm hearing implied here.

60's back in today and filled up with first tank of E85
Running surprisingly good. Trims are craptastic, but I'll start messing with them when I get a couple tanks of corn through.

Stopped in a buddy's shop and got him to look over my car. From his perspective the rust isn't as bad as I was thinking. Rockers and front fenders will need replaced. He said he can patch in the rear quarters, they really are not that bad. Zero rear shock tower rust, whew. Was actually the first time I looked at them. So, I'm gonna be doing a lot of prep work, pulling apart the interior and exterior trim, to save him some time and me some $$. Hopefully I'll find some rust free fenders at the yard, there are plenty of Impalas there so fingers crossed. Debating on pulling the engine and repainting the bay too, but not sure it's worth the trouble. Think I'll just get rid of the stickers and clean it up real good. Not liking the red/black theme so much anymore, so I have something a little more "sophisticated" in mind. Got all materials to redo brake lines, not really looking forward to that. I'd like to hold off till I get some SS lines and dual piston calipers.

But, just gonna get the car tuned right and enjoy it a little. My neighbor agreed to a night at the track with his Challenger. He's only done headers and tune and never had it at the track. Before that happens I want to see if this 2.25" pulley is tune-able on e85. Really tempted to slap it on now, but I'll wait till i'm on pure corn. Shouldn't take long, I was averaging 21mpg on the highway tonight lol.

Oh yea, I mentioned earlier that I thought I had a bad cv. Then when I got it torn apart I noticed the bearing was what was making the squealing noise. So I replaced both front bearings. HOWEVER, I still get a grinding noise from the front only when in reverse and the wheel is turned to the right. And it kinda feels like a brake is dragging, but rotors and pads are new all around. Is this common symptom of a bad cv joint?

You're gonna love the E85, just put the IFR table in for the 60's, then set the injector skew to 130. Trims should be the same as they were before. Didn't even know they made a 2.25" pulley, damn son, getting a bit out of the efficiency range of the M90, lol. Got the last of the gas out of my regal tonight, 100% E85 now. Still need to get a tank through the bonne, and the 60's installed once they come in so I can use boost again, bonne will be running a 3.2, regal on stock pulley/injectors.

Originally Posted by 99GT2dr

You're gonna love the E85, just put the IFR table in for the 60's, then set the injector skew to 130. Trims should be the same as they were before. Didn't even know they made a 2.25" pulley, damn son, getting a bit out of the efficiency range of the M90, lol. Got the last of the gas out of my regal tonight, 100% E85 now. Still need to get a tank through the bonne, and the 60's installed once they come in so I can use boost again, bonne will be running a 3.2, regal on stock pulley/injectors.

There's my trim problem. I put skew at 125%. I was thinking 130 but didn't double check. And I've read the defacto guide probably a dozen times lol.

And I meant 3.25...sheesh. Sleep deprivation is brutal....wait, what's that.....never mind just my cat.

Yeah, 2.25” on a m90 would probably split atoms.

Did you get the siemens deka 60's? If so, how's the idle with them?

Originally Posted by 99GT2dr

Did you get the siemens deka 60's? If so, how's the idle with them?

Yeah. Idle is actually better. I was still a little lean with the L67's, and the 60's plus the e85 has smoothed things out. Probably be better when I fix the skew. Wideband varies between 14.8-15 at idle.

What's your AFR at WOT? What should I shoot for? I've heard its safe even over 11. Tonight I was seeing 10.8 ish.

Well I don't have a wideband, so couldn't tell you my actual afr. On the bonne I can't go WOT yet, but regal is 11.8 commanded, stock '05 GTP timing table, no kr fully heatsoaked with 3 adult passengers and AC on in 90* weather. Only mod left on it is a 3" catless dp. When you start leaning it out, do it in .2 increments and keep a good eye on KR, when you see KR just drop it .2-.3 and call it good. Make sure you tune it in the worst conditions, ofc. Little rich is always better than a little lean.

Good to hear about the idle, not expecting mine to be smooth because xp, but glad it won't get worse, lol.

Did you just go 11.8 commanded through the whole table?

The Base_PE_AF table, yeah. Any time I change that, I change the whole table to the same value.

Originally Posted by 99GT2dr

The Base_PE_AF table, yeah. Any time I change that, I change the whole table to the same value.

You are freakin awesome dude.

So, I got some really really really good news, that no one but me will probably care to know but oh well lol. I've been getting some misfires on cy3. So I thought, what the hell, car still has original coil packs on, might as well get some new ones to rule them out. ACDelco are only 22 bucks a piece, so cheap maintenance. Popped them on when I got home and went for a ride. Soon as I get on it it REALLY started acting up. Spittin and cussing, the car too, I took it back home. I had an extra set of wires..still waiting on a NEW set to come in from Amazon, so I put them on. Wait, back up...the misfire was happening on cy3, so I swapped 3 and 5 plugs wires and this misfire followed the bad wire. But I was also randomly getting misfire on other cylinders. THAT's when I put on the spare set of wires. Took it for a spin and..>>WOW!!! This is the FIRST time I've actually felt my car running like I thought it should be. It actually PULLED, OMG lol. And earlier I topped off with my second tank of E85, so the mixture is getting closer to pure corn. Result....NO knock, just a little blip every now and then, but none at WOT. Oh, and I put on the 3.25 pulley yesterday.

Sorry about the childish giddiness, but I finally feel I got paid for my hard work. I'm only at 13 degrees at WOT, so I think there is more power to be had. I did run a new tune where I stuck a the stock timing tables in from an 04 gtp. Thanks Scott for that tip. I'm sure that helped because all my noobish eagerness has probably mangled my timing tables trying to learn how to use Table Modifier. Happy vibes to all that have chimed in and helped. I finally have a stable platform that I can tweak. Got the new glasspack in the mail yesterday, so hope to have it on the car this weekend. All I want to hear is that blower whine And I scored a new 04 1" radiator that I'm gonna try to install soon. Car seems to run warm since I reverse flushed the Dex out of it, probably plugged somewhere.

Now that I can get some good scans I'm gonna get the trims dialed in and then hit the track. Hope I'm at least out of the 17's lol. If not, cam might happen sooner than I planned.


Edit: for those who don't care to read my rant, bottom line: If your car has over 130k and you are still running stock coil packs, slap yourself and install some new ones.

Good to hear it's performing as it should! I bet that pulley made it feel like a whole different beast, lol.

I'm sure the pulley helped, but how much I'll never know. The car had been screwed up since day one, but I had no idea how bad till I got the new coil packs on. Wasn't getting a lot of misfires. I attributed the hesitation to the plugs gap, tightening them up helped. But now, its like a GO switch was flipped on. Night and day difference. My WOT a/f even improved greatly. Without even changing the pe table, now I'm 10.8-11 where I was 10.2-4. Just had no idea my ignition could do this, and the whole time I was trying to tune around it. Duh.

New plug wires are going on tonight so it might even have more to give me.

And if I can creep the timing up to 16ish without knock, I'm curious how low the e85 will let me go. 3.1"? 3? 2's?

That's a pretty good plan, just run the smallest pulley you can get away with on 16-18* timing. You're gonna need some kind of valvetrain mods soon though, even with E85, engine still gotta flow air. I imagine a set of rockers would probably make a pretty big difference being on a 3.25 pulley. I may get a 3.0, but that's probably as low as I'll go, it gets way hotter here in TX than OH.