Sorry..no answers here but I am interested what would be required. The advantage would be a 3.91 ratio vs the 3.43 we have and beefer gears w/positraction and beefier case.

Questions:
1. We will need new axle shafts (2). Will they bolt to our hubs?
2, The V has a different 2 piece HD drive shaft. What's required?
3. Will the differential housing have the same mounting locations?
4. How will this effect my speedo and other related electronics?
5. Have I forgotten anything?

If it can be done it would greatly improve my acceleration and give me an LSD which I do not have now. What's you thoughts?

It appears no one knows squat.:( It seems the least evasive of the mods like turbos, SC and ECU mods. It should look OEM factory and not a warranty issue. I changed the gears in my old Corvette and my Road Runner. Both made remarkable difference in acceleration.

Probably need new wheels :) since you might need to switch to the 6 lug

Probably need new wheels :) since you might need to switch to the 6 lug

I don't know. Maybe the axles will hook up to my hubs?

Will the CTS-V gears transfer to our carrier assmbly?

Got hook up with Jon, our canadian friend, as he has both the CTS & CTS-V

Getting the speedometer to work right may require an external device. I did a little research on what is required to reprogram the ECU so that all the DIC stuff would be correct and that gets so far out of hand so quick it'll make your head spin. It can be done, and if anyone has already had it done it's easy but if you have to foot the bill it's staggeringly expensive.

Sorry Robert, but I'm not THAT mechanical lol.

You could probably ask James, he might be able to help you out. I've asked him a couple questions before and he's always found an answer for me.

I was thinking about putting a Driverselect shifter into my CTS and get the shifting option, but he said it takes more than that. So yeah, I'm sure he's your best bet at answers.

i thought the cts-v had 3.73 gears in the rear?

I need to ask to be sure but I think the gear ratio can be programmed by the dealer with a TechII.

you wont need new hubs, the axle splines willliine up just fine.

the stock drive shaft will probably be fine. the V has the HD two part drive shaft becuase the ls6/ls2 is a very torquey engine and might snap a normal drive shaft.

from what i have heard on the solsitce forums the cases are the same, the internals are different for the Diff's. it should bolt up in the stock location, the width hasnt changed so the stock half shafts should still work.
this seems to be an upgrade involving the internals of a cts-v diff swapped into the internals of a cts diff.
(further mounting and size clues: the bmr brace for the V differential also fits the cts differential)

we'll have to call a dealership to see if they can change the gear ratio using the tech II, although I have heard this can be done.
aftr the computer gets the correct gear ratio everything else like your speedo and odometer and tranny shifting should be fine.

-K

. I changed the gears in my old Corvette and my Road Runner.


You had a Road Runner? My dad has on in his Garage that he hasnt take out like in a year. Its a cherry red with a vynal top....1968 with a 383..Next time he takes it out I'll snap some pics

Possible better idea. Get a 3.73 ring and pinion from a 3.2L manual trans CTS. You should be able to order just these parts. Then have a rear end shop put them in a 3.6L posi CTS unit. Man, I miss the 3.73s my old CTS had.

i thought the cts-v had 3.73 gears in the rear?

I need to ask to be sure but I think the gear ratio can be programmed by the dealer with a TechII.

you wont need new hubs, the axle splines willliine up just fine.

the stock drive shaft will probably be fine. the V has the HD two part drive shaft becuase the ls6/ls2 is a very torquey engine and might snap a normal drive shaft.

from what i have heard on the solsitce forums the cases are the same, the internals are different for the Diff's. it should bolt up in the stock location, the width hasnt changed so the stock half shafts should still work.
this seems to be an upgrade involving the internals of a cts-v diff swapped into the internals of a cts diff.
(further mounting and size clues: the bmr brace for the V differential also fits the cts differential)

we'll have to call a dealership to see if they can change the gear ratio using the tech II, although I have heard this can be done.
aftr the computer gets the correct gear ratio everything else like your speedo and odometer and tranny shifting should be fine.

-K
Kael, I remember a Techline article that said that it is not a matter of changing a value in a window. You have to reprogram everything that makes use of the rear end ratio. It said it is more like installing a program patch and it is a huge job to create that patch. If the proper patch exists it's easy, otherwise it's prohibitive.

crud. well leave it to GM to make it as hard as possible on us.

I ran a program for a brand new 4l60e for a hot rod build up (friends thing) you just plugged into it with this tool (i think it was a shop version of a techII) and there was a section for programming the ecm to work with the new tranny, there was a line that said "Gear Ratio" you just typed it in and viola, all done.

crud. well leave it to GM to make it as hard as possible on us.

I ran a program for a brand new 4l60e for a hot rod build up (friends thing) you just plugged into it with this tool (i think it was a shop version of a techII) and there was a section for programming the ecm to work with the new tranny, there was a line that said "Gear Ratio" you just typed it in and viola, all done.
The article said there was a library, so to speak , of these patches. If there was a patch for the tire size you wanted or rear end ratio already in existance you were okay but you were SOL if you were breaking new ground until the factory wanted to do it. I can't access Techline anymore so I can't look it up.

Any updates?

wow, this is from a year ago..

anywho..
the hptuners software is out so you can change the root gear ratio in the program.
what koz said was correct to an extent but all of the software does use a single root value for the gear ratio, this is the same thing that is changed for tire size.
otherwise you would have to use a hardware solution like a modified sprag or a signal interceptor.

the normal cts would run better with a 3.73 and the V would benefit from the 3.4X (too lazy to lookit up right now) because of a bit less torque off the line.

It appears no one knows squat.

It doesn't make your car stunt, so no one cares.

I wrote a bit on this subject on the thread concerning adding a limited slip differential.
I changed my CTS-V rear ratio from a 3.73 to a CTS ratio of 3.42 for several reasons. I think the stock first gear is too "short". I wanted a higher ratio in 5th for in-town cruise; and I wanted a higher ratio in 6th for highway cruise. For instance, 71 mph used to be 2000 rpm. Now it is more like 1800 rpm. Note, the change is not radical. Note also, a 3.42 is what a Corvette uses with the Z51 suspension.

The outer demensions and mounting points of the rear end castings are identical between the CTS and CTS-V. There are two versions though. The earlier version does not have the reinforcing ribs contained later. Not a big difference as owners of CTS-V can easily break their rear ends with a hard launch with wheels hopping. Note, a 3.42 rear seems in my case to hook up a bit better than the stock 3.73, less wheel hop, but that is just an informal opinion.

Before you embark on a gear ratio change do the math. You may not like the results.

The CTS-V and CTS have completely different drive shafts which manifests in completely different pinion gear endings. The CTS has a cone-like protrusion, which I easily cut off to adapt to my CTS-V. I can't see anyone successfully welding such an end piece to a 3.73 pinon gear.

Then you have to determine whether or not the CTS axels are the same as the CTS-V. If they are not, then forget about using the CTS-V's limited slip differntial unless you are prepared to go all the way in replacing axels and whatever is attached thereto. There is another wild card: the CTS-V has a six-lug wheel pattern, which is unique.

As for cost, I bought a barely-used CTS-V spare rear end on eBay for $225. It was erroneously put in the CTS section. Otherwise it should have gone for $500+. The 3.42 ring and pinion set cost about $310.
I did the gear change on my bench for nothing, but I am getting too old (67) to do the work on my back in a cold garage anymore, so I farmed out the installation for about $400. I paid way too much for the installation, but that's life.

Possible better idea. Get a 3.73 ring and pinion from a 3.2L manual trans CTS. You should be able to order just these parts. Then have a rear end shop put them in a 3.6L posi CTS unit. Man, I miss the 3.73s my old CTS had.

^^This, right here, seems to have been brushed over, and sounds like a much more feasible idea...since it would be the unit from one V6 "base" car to another, so hubs and all else would remain the same.

I disagree. I think changing the entire unit would be easier. Seeing that I have done both on several cars I feel safe in saying so.

Now, as far as money goes, yes the straight gear change may be more feasible, monetarily speaking.

alright gentlemen we are having mix feelings around here. I'm in the process of looking for away to up my rear from 3.42's to 3.73's . So the 03 manual cts has a 3.73 gears rear end stock? If so I'm going to start searching for 1 , and try this swap to my automatic 03 cts. Does anyone think i'll run in to any problems ?/ I wouldnt think so seeing how it should be the same mounting points axle splines etcc... what you guys think?

There is not a mix of feelings, just opinions. Either way would be right.

You will have no issues. You can just order a gear set in a 3.73:1 ratio for your car and be done with it. Spend the $200-$500 to have it installed and you will be good.

I just wanted a stronger case and better ratio. I do not like setting up gears, but for ME swapping an entire differential/pumpkin/rearend is way easy.

A Gears swap is not hard, but I leave them to the professional.

i tried looking up the part for 03 ring and pinion and there was no option to get manual or automatic set. also while your in there would it not be possible to a limited slip diff?

For me, I allready have the limited slip. So just changing the gear ratios from 3.43 to 3.73 rearend isn't worth the whole effort, I dont think the gains in performance would be enough to warrant the money. I'd love to upgrade to a 4.11 rearend.

I did the 3.42 to 3.73 upgrade on my 92 Camaro and it made a world of difference. I think 4.11's would be too much unless you actually changed thepeak rpms.

Factory gears are setup on the economy side. 3.73's are perfect for our V6s.

In my opinion 3.42 to 3.73 isn't enough of a change to justify the cost. I would go straight to a 4.10/4.11 gearset as that is a more typical setup for cars with 3.42 factory stock.

In my Trans Am I had 4.33's which were awesome for performance, and it still did well on the hwy with the 6-spd. With the 5-spd auto in the CTS I would probably not go past 4.11's for a daily but you will definitely feel a seat of the pants change. Gears are usually one of the best bang for the buck performance mods in terms of seat of the pants improvement.

1. We will need new axle shafts (2). Will they bolt to our hubs?
2, The V has a different 2 piece HD drive shaft. What's required?
3. Will the differential housing have the same mounting locations?
4. How will this effect my speedo and other related electronics?
5. Have I forgotten anything?

1. I am almost sure you'd have to replace the axles, not 100% mind you. I haven't done a regular CTS rear to know, but my guess is the extra horses warrant a beefier CV shaft. (2) Not sure, but I am thinking it might.
Luke might be able to look in the catalog and check the axle part numbers to see if the parts are the same or not. He won't be able to tell if the splines will mate from hub to hub without looking at one though.

2. The input yoke is completely different. I think the CTS uses a rubber coupler, the V uses a conical metal CV joint and 6 bolts that should have loctite applied to them before they are reinstalled. You'd have to change out the yoke, and hope the splines are the same on the pinion gears.

3. Yes, the rear cradles are the same as far as I know.

4. It depends. I know on the Grandfather of the CTS... the Catera... the speedo signal was generated from the right rear wheel speed sensor. This car has used the same transmission and controller they had on the older Catera (pretty much) so maybe it is still the same. IF it is true that a WSS is used for speedo input then you are golden. If the VSS is obtained from the trans output shaft sensor you'll have issues. Changing the final drive ratio with a VSS in the transmission will screw up inputs for all kinds of things and can cause issues with transmission control, maybe not much else except an inaccurate speedo. If they are using WSS on this car as an input for speedo, then it is a total non-issue.
Transmission control might still be funky, but not much.

5. Probably, but only those who have tried would really know.

umm guys...

you do know that GM made a limited slip option for the v-6 cts right? the g80 option.

I am more interested in the limited slip than in the minor gear changes.


actually.. hell yes i want a 3.73. that would really pep the cts up where it needs it.

I LIKE that I can go 140 mph but I would prefer to get to 100 faster.

well if someone could find the part number for the ring and pinion for the 03 manual transmission we would be set right?

Not sure how many of you guys have done a ring and pinion before.
It can be a real pain to swap. You have to get the preload, backlash and all the stuff set up right when you do it. Most of the getrag units we just replace, we don't overhaul them.
It is doable, just not as easy as taking it apart and putting it back together.
I guess it could be if you get a good pattern when you get the gears in.
I haven't done one of these so I don't know how hard or easy it is to set up.

That is exactly the reason I was saying that I would rather change the whole diff, instead of the gears. It would probably cost about the same, if you had someone professionally set up the gears.

I have set up several sets of gears and if you do not know what you are doing, then good luck, you might be buying two sets of gears and paying someone to fix your fk up.

Also by swapping in a V diff, it is stronger and can take the increased torque that is going to be applied to the smaller pinion.


:)

If you pull the diff and take it to a shop they can be reasonable. There is a place around here call "ring and pinion" (appropriately) that does this. All the hot rodders (errr I mean street racers..showing my age) go there. I took a rear end to them for my Malibu. I brought the rear end in (out of the car), brought the new ring and pinion and for about $100 they swapped it in and set it all up. If you take them the whole car it is more but would be an easy way to get this done.

Just make sure you find a rear-gear SPECIALIST in your area.

If you pull the diff and take it to a shop they can be reasonable. There is a place around here call "ring and pinion" (appropriately) that does this. All the hot rodders (errr I mean street racers..showing my age) go there. I took a rear end to them for my Malibu. I brought the rear end in (out of the car), brought the new ring and pinion and for about $100 they swapped it in and set it all up. If you take them the whole car it is more but would be an easy way to get this done.

Just make sure you find a rear-gear SPECIALIST in your area.don't be embarrssed about your age, you rodders had it great...cheap gas and carbeurated big blocks...now you've gotta be a computer whiz to tune your vehicle right

THE 2003-2005 CTS had an 3.73 option. part number for the ring and pinion is 89058646. we would get $333.00 plus a little shipping for it.

was that an option only for manual transmissions? or how could you find out what gear set you already have?
i'd buy the set and get it installed, hmmm maybe next spring(got to buy a hood first)
i'd probably buy new seals too, might as well seeing as i'm back there anyway

is there specific code to look for when i see a junked cts to see if it does have the 3.73 gears in the rear? I would rather get the whole pumpkin, refurbish it , and then throw it in ..

is there specific code to look for when i see a junked cts to see if it does have the 3.73 gears in the rear? I would rather get the whole pumpkin, refurbish it , and then throw it in ..3.73's only came on 03-04 Models with the 3.2L and 5 spd manual transmission.

sweet i think i'm doing this next spring or sooner. cash permitting, and maybe i'll hold on to my cts a little longer.

THE 2003-2005 CTS had an 3.73 option. part number for the ring and pinion is 89058646. we would get $333.00 plus a little shipping for it.I could be wrong, but I dont think any 05's came with 3.73's. By then the 3.6L and 6 spd Aisin was here, and the 3.2L and 5 spd Getrag was gone.

whats the code # for that if anyone knows .. I'm going to try this swap , and do a write up .

The 3.73 gears, according to my catalog, came in 03-05 MT or AT cars option code was GT4

there is also a 3.91 option that was available in 04-05 cars with a MT. the code for that was GW1

hmmmm 3.91 that's food for thought. anybody have any ideas how much top speed that would be lost?

keeping a top end of more than 120 would be good for me.

yea 3.91 rear might give it a little more bit anyone with a 04-05 mt cts have the 3.91 rear?? Any thoughts ?

The 3.73 gears, according to my catalog, came in 03-05 MT or AT cars option code was GT4

there is also a 3.91 option that was available in 04-05 cars with a MT. the code for that was GW1Are you serious? Why do dealers never know about these options? I specifically asked about different gear ratios when I ordered the car...I was told 3.43 was the only available gear ratio from the factory. And from reading on this site, it's been said numerous times the 3.73 was only available on 5MT's with the 3.2L.

So, if these options exist, why do the dealers not know this?
Why does the Cadillac website not mention this?
Why does the CTS brochure not mention this?
And again, why do authorized dealers not know this, especially when Ive asked them specifically... Is there a way to find a list of ALL options available?

PS. Yea, thats a rant, but answers are welcome :)