Cheap rear differential replacements
09-14-2011, 12:58 PM
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Cheap rear differential replacements I am new to this site, but wanted to offer some helpful info to anyone who might be interested. I'm sure this has been covered somewhere but here it is again. I have always been a fan of the V, and recently came across an extra clean supercharged 05 that I couldn't pass up. After about a month I blew through the original rear diff. The housing, gears, and bearings were all damaged, but the limited slip carrier was still fine (as are every one I've seen blown). I found used CTS-V replacements for around $750-$1300. What I did was purchase a used unit from a SRX (3.73 opt GT4). For some reason they are much cheaper (I paid $250), and have the same housing and gear ratio. My unit was from an 06 (newer gen, stroger) and had only 27k on it with a one year parts warranty. The main difference is the carrier is not limited slip (not opt gt80 I believe). I bolted the ring gear to my old limited slip carrier, and it dropped right in replacing the non posi unit (less than 5 mins!). The only other difference is the input shaft to the drive shaft (spprox. 1") has to be cut off to install on the V (another 5 mins.) and the old connector must be used. Installed and working great after a week of torture it is still very quiet and smooth with no problems. I even bought a second unit as a back up, and still paid less than a factory V unit. I am currently manufacturing an iron “cage” for my backup unit to help strengthen the housing. I have a friend with a machine shop so if this works out well enough I might be open to having some extras built if anyone is interested. This has probably already been done somewhere but I have not found anything. If anyone has any questions or needs some advice on this type of replacement I will do what I can to help out with any info I can offer.
09-14-2011, 09:19 PM
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Some of the SRXs do have 3.23, but alot of them have 3.73. You're right all of the housings are the same (CTS, CTS-V, SRX, as well as some other models), but if you get one that's already got 3.73s you don't have to spend extra $ on gears. Just swap the posi carrier with your original, and use the new ring gear. Good to go. Just a quick and easy way to save some $$$. And with as many rear diffs as I've seen people going through, any tips or tricks can help out alot.
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09-14-2011, 09:42 PM
#8
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Good info. I have replaced all the bushings in the rear of mine & checked the driveline best I could & I am still getting a clunking when I put the clutch in or shift hard. I think I have some killer wear on the ring & pinion cause I pulled the season plug and the magnet end looked the same diameter as the threads due to all the shavings it had picked up.
09-14-2011, 10:42 PM
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I just bought my 05 V with 27k mi about 2 weeks ago, and same story, it has a clunk in the rear, as well as some whining. I read somewhere that the whine is due to a warped housing, not the differential itself, and the clunk is almost always due to the front diff bushing. I'm looking into solutions, and i'm glad to have run across this. Since I do not plan on drag racing my car, and just using it for it's awesome daily driveability and handling, upgrading is kinda pointless. I guess i'll have to identify what is actually bad, and what parts are salvagable. 
09-15-2011, 01:10 AM
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It just depends which generation (there are 4 I believe). You can actually get a newer gen regular CTS housing and it will be beefier than a first gen V housing. And yes you can probably pick one up for $150, but it won't have 3.73s (only the CTS V-series offers 3.73)...and the gears for these things are super expensive for whatever reason. So essentially you are spending an extra $100, give or take, for the 3.73s offered in the SRX.
09-15-2011, 12:25 PM
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i can pretty much agree with the 3.23's. I want driveability and some fun in the corners, not maximum acceleration. I think the current gearing is almost too short. My plan is to first replace the engine and trans mounts (tomorrow), then determine where it is still "clunking". I'll probably end up with a new front diff bushing and diff block. Then i may be swapping out the differential and housing.
So the common problem for the whine is the differential itself, correct? It's not some sort of strain being put on it from a warped housing, in which case the housing can just be replaced, and oem diff reused??
So the common problem for the whine is the differential itself, correct? It's not some sort of strain being put on it from a warped housing, in which case the housing can just be replaced, and oem diff reused??
09-15-2011, 12:31 PM
#15
After a few hard launches, every single one of these oem diffs whine. There's too much TQ on a little aluminum case.
Clunking has alot to do with the carrier bearing on the oem driveshaft.
Clunking has alot to do with the carrier bearing on the oem driveshaft.
09-15-2011, 12:46 PM
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I don't think you would be happy with 3.23s. I would try out some 3.42s first (maybe a happy medium). You can purchase a diiferential from several different models that use a 3.42 non limited slip very very cheap. Just replace the carrier with your limited slip one and you're in business. Oh, and the problem does seem to stem from the aluminum housing flexing under high torque. That's why I am currently fabricating an iron "cage" or "girtle" to help keep it from flexing.
09-15-2011, 09:21 PM
#17
I don't think you would be happy with 3.23s. I would try out some 3.42s first (maybe a happy medium). You can purchase a diiferential from several different models that use a 3.42 non limited slip very very cheap. Just replace the carrier with your limited slip one and you're in business. Oh, and the problem does seem to stem from the aluminum housing flexing under high torque. That's why I am currently fabricating an iron "cage" or "girtle" to help keep it from flexing.
Hmm. So you can bolt our carrier to the 3.42's? Would the computer/speed sensors freak out due to a gear change?
09-16-2011, 01:07 AM
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Yes. You wouldn't have to, but I would definitely use your limited slip carrier for the obvious performance benefits. The car would need to be tuned for a different gear ratio.
06-29-2013, 08:16 AM
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Please helppppp!!!!! I have a friend with a machine shop so if this works out well enough I might be open to having some extras built if anyone is interested. This has probably already been done somewhere but I have not found anything. If anyone has any questions or needs some advice on this type of replacement I will do what I can to help out with any info I can offer.[/QUOTE]
HelloSir! greeting from Poland, I have bought 2005 Cts -V ( the second or third in thi country) two days ago, and yesterday cruising on the highway with around 65mph I heard the noise and this is it... today the mechanic told me me rear diff is broken, no ile, etc, probably need to change at all as I was still driving ( I was with my kid) to get home , slowly but still it was around 20 miles....
Have you made this " cage"?can you help me ? I would buy from you the whole diff erential if possible just to swap it into my car.....this is really difficult to be passionate of this car in here,no mechanics, no parts ...
and I hoped to have fun and go for hildays with my daughter soon...
Also I would need some advice where I can get some smaller items for this car with good price... and t be shipped internationally..
great thanks in advance for any help...
Marek
HelloSir! greeting from Poland, I have bought 2005 Cts -V ( the second or third in thi country) two days ago, and yesterday cruising on the highway with around 65mph I heard the noise and this is it... today the mechanic told me me rear diff is broken, no ile, etc, probably need to change at all as I was still driving ( I was with my kid) to get home , slowly but still it was around 20 miles....
Have you made this " cage"?can you help me ? I would buy from you the whole diff erential if possible just to swap it into my car.....this is really difficult to be passionate of this car in here,no mechanics, no parts ...
and I hoped to have fun and go for hildays with my daughter soon...Also I would need some advice where I can get some smaller items for this car with good price... and t be shipped internationally..
great thanks in advance for any help...
Marek