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New member here, just reaching for any help if someone has swapped out a rear diff in their c5?
I currently have the 2.73 in my ‘99 c5 . I was wanting to jump up to the 3.15 or 3.42 from a manual c5. Will both of these rear diffs fit the same as my 2.73 rear diff does currently? Thanks for any help.
Another member here recently asked about this swap. Posting this for you as an FYI as you do need to transfer the seal plate if the diff came from a manual C5.
If you're going to bother spending the money, get at least the 3.42. Totally worth it. They come up for sale here and there but get snagged up quickly.
If you're going to bother spending the money, get at least the 3.42. Totally worth it. They come up for sale here and there but get snagged up quickly.
besides finding a 3.42 rear diff, any other things needed for the swap out? Thanks
Check out my thread here. Lots of good info and links to build threads in it. I am going to tear down my diff before installing and check the Bellville washers so I am replacing some parts that if you just do a swap you won't need to do.
There is a 3.42 for sale here for $350 + shipping from California (expect $100 if close to Cali, $200 if not) but at $550 that is a good price. Most are $750 - $1500.
Parts that I have identified are:
Must have parts - all priced from RockAuto
24228816 - differential seal x 1 $38.79 - This is the seal "bearing" that goes in the middle of the side plate that you will transfer from your 2.73 to the new 3.42
19259473 - axle shaft seal x 2 $17.72ea - These are the seals that go in the right and left covers where the axles go into the diff
12369456 - Main / Output Shaft seal x 1 $9.56 - This is the o-ring that goes around the side plate that you will transfer from your 2.73 to the new 3.42
89021677 - Diff oil with slip modifier added - 2 quarts or any brand of your choice
Tune for 25% reduction in partial throttle and WOT shift points (according to tblu92) $200 ~ $250 local to me
Parts if tearing down the diff before install
89047953 - Diff side cover seal x2 $22.79ea - These are the o-rings that go on the left and right side plates
89047954 - Diff rear cover seal x 1 $6.53 - This is the o-ring that goes on the rear cover.
19132817 - Diff Pinion Shim (also called the Bellville washer) x 2 $ 7.25 Note, not needed if doing complete clutch pack below as they come with it.
19132906 - Clutch pack kit x2 $102.79
12369457 - Side plate x1 $45'ish This is the side plate that you take from your 2.73 to put in the new 3.42 if you don't have one or you don't want to remove the one you have. It is discontinued but I found a few places that had it in stock.
Tune for 25% reduction is partial throttle and WOT shift points $200 ~ $250
If you are doing a teardown and you want further mods for higher horsepower then you may want to change the output shafts to the better Z06 shafts. LH C6 Z06 output shaft: 89060119 $60.79 x 1 RH C6 Z06 output shaft: 89060120 $60.99 x 1 RH C6 Z06 Side gear: 19180962 $75.79 RH C6 Z06 Side gear retaining ring: 12458084 $5.07
I "think" this is everything. I will be doing my diff teardown 10/28 and the diff install 10/30. I'll report back in my thread what I found after each
Last edited by Autoeng; Nov 7, 2020 at 10:42 AM.
Reason: correct qty of seal plate from x2 to x1 and moved seal 89047954 to diff tear down parts
Check out my thread here. Lots of good info and links to build threads in it. I am going to tear down my diff before installing and check the Bellville washers so I am replacing some parts that if you just do a swap you won't need to do.
There is a 3.42 for sale here for $350 + shipping from California (expect $100 if close to Cali, $200 if not) but at $550 that is a good price. Most are $750 - $1500.
Parts that I have identified are:
Must have parts - all priced from RockAuto
24228816 - differential seal x 1 $38.79 - This is the seal "bearing" that goes in the middle of the side plate that you will transfer from your 2.73 to the new 3.42
19259473 - axle shaft seal x 2 $17.72ea - These are the seals that go in the right and left covers where the axles go into the diff
12369456 - Main / Output Shaft seal x 1 $9.56 - This is the o-ring that goes around the side plate that you will transfer from your 2.73 to the new 3.42
89047954 - Diff gasket x 1 $6.53 - This is the o-ring that goes between the diff and the tranny, I also found 89060114 $9.02 as an alternate that looks more like a traditional gasket. I ordered both and will see which I install
89021677 - Diff oil with slip modifier added - 2 quarts or any brand of your choice
Tune for 25% reduction in partial throttle and WOT shift points (according to tblu92) $200 ~ $250 local to me
Parts if tearing down the diff before install
89047953 - Diff side cover seal x2 $22.79ea - These are the o-rings that go on the left and right side plates
19132817 - Diff Pinion Shim (also called the Bellville washer) x 2 $ 7.25 Note, not needed if doing complete clutch pack below as they come with it.
19132906 - Clutch pack kit x2 $102.79
12369457 - Side plate x2 $45'ish This is the side plate that you take from your 2.73 to put in the new 3.42 if you don't have one or you don't want to remove the one you have. It is discontinued but I found a few places that had it in stock.
Tune for 25% reduction is partial throttle and WOT shift points $200 ~ $250
If you are doing a teardown and you want further mods for higher horsepower then you may want to change the output shafts to the better Z06 shafts. LH C6 Z06 output shaft: 89060119 $60.79 x 1 RH C6 Z06 output shaft: 89060120 $60.99 x 1 RH C6 Z06 Side gear: 19180962 $75.79 RH C6 Z06 Side gear retaining ring: 12458084 $5.07
I "think" this is everything. I will be doing my diff teardown 10/28 and the diff install 10/30. I'll report back in my thread what I found after each
thanks a bunch , and I’ll wait to see how ur teardown and install goes later this month.
My estimated cost so far:
$235 for the diff - already purchased so this is firm
$200 for diff tear down parts - already purchased but may go up as I did not buy clutch packs and if they are overly worn I may have to get them
$300 time on the lift at my mechanics shop $250 for the tune
$985 total
I did notice that it sold also when I went to look at it. Rear diff’s with 3.15 seem more common, I may go that way to get some kind of improvement from my car. It seems to be such a dog on taking off. I don’t take off hard anyway, but the engine stays in the low rpm range always and if u need to get going quickly, it seems to have to downshift and it has a lag in time to respond and take off. Just hate to do the 3.15 and be disappointed.
I would hold out for the 3.42. FB Marketplace is where I found the one I got.
Corvettes Of Westchester (CoW) offers a Cob Booster programming change that is said to improve low end performance but I haven't looked into it much as his customer feedback is all over the place (meaning good and bad).
You could also do a custom DiabloSport tune if you purchased a DiabloSport tuner. I have one that came with my car and have a canned 91 octane tune loaded but have never run the car with the stock tune so I can't give feedback if it made it better. I will probably have to go back to stock tune since the diff tune is done by HP tuner at which point I may sell the Diablo.
Originally Posted by Todd Goodson
I did notice that it sold also when I went to look at it. Rear diff’s with 3.15 seem more common, I may go that way to get some kind of improvement from my car. It seems to be such a dog on taking off. I don’t take off hard anyway, but the engine stays in the low rpm range always and if u need to get going quickly, it seems to have to downshift and it has a lag in time to respond and take off. Just hate to do the 3.15 and be disappointed.
My estimated cost so far:
$235 for the diff - already purchased so this is firm
$200 for diff tear down parts - already purchased but may go up as I did not buy clutch packs and if they are overly worn I may have to get them
$300 time on the lift at my mechanics shop $250 for the tune
$985 total
Ive done it twice, and the 2nd time took me almost 5 hrs to remove the diff/trans, and about 6-7 for install, not counting time to clean, or install new seals, and other parts. If you can get someone to do it for $300, you have found a GREAT deal. ALSO consider a bigger converter if you really want to have fun. I went with a Yank SS3200 with my 3.42. Its a different car.
I did notice that it sold also when I went to look at it. Rear diff’s with 3.15 seem more common, I may go that way to get some kind of improvement from my car. It seems to be such a dog on taking off. I don’t take off hard anyway, but the engine stays in the low rpm range always and if u need to get going quickly, it seems to have to downshift and it has a lag in time to respond and take off. Just hate to do the 3.15 and be disappointed.
For the amount of work it is to swap out the differential, make it worth your time! Even though the 3.15 was sold as the "performance" rear end option (my 1998 'Vert came with it) - going to the 3.42 and a higher stall converter would be more worth all that the effort. I almost went that route originally when I wanted to pep things up, but decided on a 6-speed and an RKT built 3.90 instead.
When dropping the cradle / removing the diff, does the gear shift need to be removed or can the interior of the car stay in tact?
Thanks
Rob
Hey Rob- I just did a diff swap this past weekend in an MN6, and if you are only swapping the diff you do not need to remove the gear shift. You also don't need to remove the torque tube and the trans. You have to remove the rear cradle and axles, remove the heat shield (like 36 bolts) and then you can lower the torque tube and the trans enough, while keeping them bolted together and attached at the clutch housing. The motor mounts will flex enough to lower the diff just enough to clear the rear tub on an a downward angle.
Having two extra sets of hands will help. One to lower the jack your trans is on, one to lower the jack the diff is on, while you pull the diff off the studs and turn it to clear the tub. You will need to turn the diff slightly while pulling it off the trans studs. There will be a bolt hole in the casing of the diff that protrudes and hits the tub if you don't turn it while removing it. Just be careful not to snap or kink any brake lines. Job was not as hard as some have described.
I did notice that it sold also when I went to look at it. Rear diff’s with 3.15 seem more common, I may go that way to get some kind of improvement from my car. It seems to be such a dog on taking off. I don’t take off hard anyway, but the engine stays in the low rpm range always and if u need to get going quickly, it seems to have to downshift and it has a lag in time to respond and take off. Just hate to do the 3.15 and be disappointed.
I had, and still have it on the bench, a 3.15 diff in my 2000 C5. I installed a 3.42 out of a C5Z06, not because I didn't like the 3.15, more because I installed a 3200 Yank converter. The lower gear of the 3.42 makes the converter feel "tighter". I'd be happy to sell you my 3.15. It would need nothing but a good cleaning, and a long side output shaft. BUT-I REALLY advise against it. If you're going to go to that much work, I'd go for the 3.42. It's going to be quite a job for most people, or an expensive job for the rest of the guys who want to pay for the swap. Like I said, that much labor/$$$, go for the 3.42. With an A4, I would advise against going with anything lower, like a 3.73, or 3.90. The M6 trans guys can do that, because they don't have such a low 1st gear, and have higher OD gears than the A4. The 4L60E has a very low first gear. I did the math once, and the 3.42 gear coupled with the 4L60Es 3.06 1st gear equates to running a 4.22 rear end (which was never made, just using for comparison!) in a 350 or 400 turbo trans, so you'll have real traction issues with anything lower than the 3.42. Just my 2 cents......
Rear end swap
