El3ments

Hello. I recently bought a 2004 C5 with 42,000 miles on it. It has a procharger super charger kit install.

I was driving it and shifted into second. I heard a loud popping sound and a pulsing thumping noise. I pulled over and towed the car home. We had issues with the rear wheels locking up as we tried to pull the car onto the flat bed.

My question/issue is I'm trying to verify it's the differential that is the issue before I buy a new one. I am able to drive the car around at low speeds and there is a popping sound as the wheels lock up a bit but I am able to keep driving the car. I was able to drive my car into the street, turn around and then pull it into the garage for example. The problem seemed much worse when it initially occurred.

I have the car on jack stands. What can I do to verify it's the differential and not the tranny/other issue?

Thank you for your help.

El3ments

Last night I put the Corvette into neutral and turned the rear wheels by hand. I was able to make almost a complete turn until the wheels began to lock up. Sometimes I could force the wheels past this locking point other times it seemed to lock very hard.

I can spin the wheels both ways and the same issue occurs. Does this seem like it's the differential?

Bill Curlee

I would have to say your differential ring and pinion are TOAST.

The only way to POSITIVELY tell what all you need is to drop the rearend. You can seperate the differential from the trans with the drive train still in the car. You have to drop the rear cradle

There are a couple of great write up on this very procedure.

Some questions:

1- What rearend do you intend to replace it with? Stock, Aftermarket modified built rear??

2- What ratio rear do you have now?

IF,, you go stock, there are several things that you can do to beef up a stock rear on your own. You can install C6 ZO6 output shafts, clutches and belleview limited slip clutch springs.

I would be REALLY careful driving that car with the problem that you have!!! If you get broken metal wedged between the ring and pinion teeth under power, you WILL SPLIT THE Differential case and possibly snap off the transmission output shaft.

If you want a REALLY good differential specialist, contact Rick Kim RKT56

RKT56

http://rkt56.com
Phone number: 301-257-0930
205 Bucheimer Road, #C
Frederick, MD 21701

Here are some very good differential post for you:


- C5, ragtopws6 , Upgrading your C5 rear with C6 Z06 guts, : http://forums.corvetteforum.com/c5-g...-z06-guts.html
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- C5, Its_Go_Time, Output Shaft Install - Left and Right: http://forums.corvetteforum.com/c5-t...post1573407966

- C5 Differential Seal replacement: http://forums.corvetteforum.com/c5-g...on-photos.html
-

El3ments

Thank you for your reply Bill.

After some reading I learned that the stock diff can only handle about 450 HP so I'm going to have to build mine is some way. Most likely I will be getting a built diff with 300m half shafts in it. This way it probably won't break again and I can modify my car more in the future without having to worry about it. However, if a used C6 Z06 upgraded diff or better becomes available I may buy it.

I have a 2004 manual so it should be the 3.42. I haven't checked yet to make sure it was the stock diff.

Would 3.73 gear ratio be to much for a supercharged car?

I drove it up on car ramps and that's where it will be staying

If I buy a built diff can I ruin the ring and pinion again? Is that a common issue?

Bill Curlee

If the unit is built correctly with the correct hardened parts, it should be fine. Give Rick a call and discuss you rearend need and desires with him. He is a VERY knowledgeable and skilled guy and will gladly answer all your questions.

He also builds bullet proof rearends with all the go fast stuff.

IMHO you should have the rear built and replace the ring, pinion, pinion carrier, clutches, 300mm hardened output shafts, RPM Cross shaft and new Belleview springs. When the differential is properly set up and the correct hard parts installed, it should be reliable for your power level.

HOWEVER,,, you now need to be concerned with the transmission output shaft. I’ve seen people SNAP that shaft in the power range that you have...

I had my spare MN12 tranny converted to a TRANSZILLA T-60/60 with the hardened output shaft.. I had the bucks and didn’t want to fool around worrying about that issue. I installed it in my 02 Z pushing a measly 450 RWHP.

No matter what rearend you get or how good its built, WHEEL HOP or drive train hop will break rearend and or output shaft so,, do all you can to prevent that!

Install a PFADT Diff Mount, better shocks, ECS Brace, etc..

How’s the rest of the drive train? Clutch, Torque tube bushings, & engine mounts?

Bill

El3ments

Quote: How’s the rest of the drive train? Clutch, Torque tube bushings, & engine mounts?

I honestly have no idea. I have only had the car for 4 months now. This is the first time I have been under it. The clutch seems fine but I don't know if it is stock or not. No idea about the bushings or engine mounts. I will try to check them out as I work on it.

Any advice on gearing for the new diff? Would 3.73 cause me traction issues with my power level?

Note: I don't know for sure what my power level is. It was rumored to be 530 WHP but I cannot confirm this until it is dynoed. I guess would be between 450-500 WHP. It has a Procharger stage 2 kit on it.

chaase

My opinion is that for a supercharged vehicle, I would stay with stock gearing. I think there were some really high HP folks that went the opposite direction to make the car more drivable.

PhysicsDude55

You don't specify in your original post, but I'm going to assume you have a NON-Z06 2004 C5.

Z06 MN12 transmissions are essentially the same gear ratios as a Non-Z06 MN6 transmission if it had 3.90's on it.

So, if you have a Z06, I would recommend staying with the 3.42s, but if you have a non-Z06 C5 with the MN6 transmission, I think you'd really enjoy having 3.73s or 3.90s at your power level. The biggest downside is you'll get a little less fuel economy. If you have a set of high performance tires, traction shouldn't be too much of an issue, just don't go around dumping the clutch all the time

El3ments

I do have a non-z06 C5. Perhaps you are right. I wasn't able to drive the car long enough in decent weather to see what my traction was like. Since I don't know how my traction is I am really in-between going with 3.42 or 3.73s. Frustrating.

3.73s isn't exactly a huge increase. I went from 4.10 to 4.44 in my AP1 S2000 and it made the car a little more fun but it definitely was not a huge difference.

El3ments

On another note. I dropped my Diff last night. I hooked it up to an axle after it was disconnected to the transmission and spun the diff with my hands using the axle. After spinning it I noticed 3 teeth missing on the ring gear.