forkliftman79
Well-known member
Has anyone ever changed the differential in their car, if so how difficult is it? I am ooking at a complete differential on line and wondering what it takes to put it in. Thanks.
Differential upgrade
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Hib Halverson
Technical Writer for Internet & Print Media
The level of difficulty depends on your skills, tools and equipment.
If you have an advanced level of DIY automotive skills, a full set of tools and a lift, the job is pretty easy. If you're going to do this on your back with the car on jackstands, it will be a little harder.
If you're a beginner with limited mechanical experience, no factory service manual, a limited set of hand tools and a pair of ramps, the job is going to be hard.
If you have an advanced level of DIY automotive skills, a full set of tools and a lift, the job is pretty easy. If you're going to do this on your back with the car on jackstands, it will be a little harder.
If you're a beginner with limited mechanical experience, no factory service manual, a limited set of hand tools and a pair of ramps, the job is going to be hard.
Pac-man
Well-known member
Because it's an awsome upgrade. Especially if your car does not have the performance 3:15 rear end, in which case it would have the 2:73. Changing the 2:73, or the 3:15 to a 3:73 or 4:10 is a great mod. I think manuals have a 3:42 ratio. The change takes a little of the top end but who goes 170 anyway. Well worth the acceleration gained from down low. This will be my next mod. Putting in 4:10's in my 99 Vert A4. I have 4:10's in my 70 Monte and it tears ass. Can't wait to put them in the Vette. That's WHY!
c4c5specialist
Technical Advisor
HI there,
Just remember, you will have to remove the rear subframe in order to change the differential.
That requires a spring compressor and some assorted fasteners and retainers.
Then an alignment would have to be done afterwards.
Allthebest, c4c5
Just remember, you will have to remove the rear subframe in order to change the differential.
That requires a spring compressor and some assorted fasteners and retainers.
Then an alignment would have to be done afterwards.
Allthebest, c4c5
c5y2k
Well-known member
Wow 4:10's in an A4? You'll be running close to 3K rpm @ 70mph. I don't have my gear/RPM chart handy here at work to give you the exact numbers. I do know 3:42's in an A4 @ 70mph is right at 2,450rpm which is plenty high for me. I can see the M6 with the 4.10s.
This is just my opinion so if the 4:10's work for how you drive your car you get the
a 
and a 
.And I agree if you are running 2.73's a gear change is a fantastic mod that you will definitely notice.
bugman34202
Well-known member
I would like to change the gears in my A4 also, probably to a 3:42, but I procrastinate due to resale value. I don't think a seasoned 'Vetter would mind the taller gears but the casual buyer or newbie to a Vette may want the stock configuration, and I don't want to change everything back just to make the car more sellable.
Good luck,
JB
Good luck,
JB
Pac-man
Well-known member
Just do it and enjoy the car. Throw in the old gearset when you sell it. You're actually doing the new buyer a favor.
c5y2k
Well-known member
If you are concerned about resale put in the 3:15s. You will still see a noticeable performance increase and the 3:15s are the stock performance gears offered as an option by the factory.
Hib Halverson
Technical Writer for Internet & Print Media
Axle ratio changes, like any other mod which results in a significant performance increase, are a "double-edged sword".
If acceleration performance is the only concern and you add the appropriate mods to strengthen axle shafts and improve rear traction, then ratios lower than the 3.15 (the OE performance axle ratio for automatics) or 3.42 (the OE ratio for manuals) makes sense.
The other side of the story, however, is that if you go lower with an A4--say 3.42 or maybe a race-only 4.10--is that you'll see a significant reduction in fuel economy. Mentioned previously was "resale value". If that's a concern, don't go that low with the axle ratio as very few potential buyers of used Corvettes will conclude a sale if they know the car gets poor mileage.
Additionally, the statement above that going to 3.42s or 4.10s will not affect the car's top speed is B.S. It will affect that significantly. Now, admittedly, that might not concern hard-core drag racers, but that top end will decrease is fact.
Finally, the lower you go in axle ratio, the more traction--ie: sticky tires--become an issue. The first gear ratio in the C4 A4s is pretty low. Add a low axle ratio and you need much more tire under the car in the back to use the increased torque at the rear wheels. If you don't have tires to match the axle ratio change, all that happens is you spin the tires at launch.
Of course, when you go to sticky tires, you increase the load on axle shafts at launch and, if you race a lot, you'll break them...so, now, your into upgraded axle shafts...followed by a stronger gearset and so on and so forth.
So...yeah...ratios in A4 cars lower than 3.15 can, in certain situations, provide even better acceleration performance, but to actually put that accelertaion performance to good use may require improvements and compromises in other areas
If acceleration performance is the only concern and you add the appropriate mods to strengthen axle shafts and improve rear traction, then ratios lower than the 3.15 (the OE performance axle ratio for automatics) or 3.42 (the OE ratio for manuals) makes sense.
The other side of the story, however, is that if you go lower with an A4--say 3.42 or maybe a race-only 4.10--is that you'll see a significant reduction in fuel economy. Mentioned previously was "resale value". If that's a concern, don't go that low with the axle ratio as very few potential buyers of used Corvettes will conclude a sale if they know the car gets poor mileage.
Additionally, the statement above that going to 3.42s or 4.10s will not affect the car's top speed is B.S. It will affect that significantly. Now, admittedly, that might not concern hard-core drag racers, but that top end will decrease is fact.
Finally, the lower you go in axle ratio, the more traction--ie: sticky tires--become an issue. The first gear ratio in the C4 A4s is pretty low. Add a low axle ratio and you need much more tire under the car in the back to use the increased torque at the rear wheels. If you don't have tires to match the axle ratio change, all that happens is you spin the tires at launch.
Of course, when you go to sticky tires, you increase the load on axle shafts at launch and, if you race a lot, you'll break them...so, now, your into upgraded axle shafts...followed by a stronger gearset and so on and so forth.
So...yeah...ratios in A4 cars lower than 3.15 can, in certain situations, provide even better acceleration performance, but to actually put that accelertaion performance to good use may require improvements and compromises in other areas
Pac-man
Well-known member
Hib, I never said that it would'nt effect the top speed. That would make no sense. I said that it would take a little off the top end. Probably could've been more clear, because by saying a little, I was thinking about 20mph. There are gear ratio charts that you can reference on the web.
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forkliftman79
Well-known member
How many hours would it take to throw one in, I was looking at the SLP complete differential, I have a lift in my garage. I am not looking to race with the car I just wan't a little more ooomf out of it. I already put in SLP long tube headers, high flow cats, down piping Zo6 mufflers, SLP performance program dyno tuned, and a vararam, and my fathers new muxtang still has more launch than my vette.
Hib Halverson
Technical Writer for Internet & Print Media
I agree. You never said it wouldn't affect top speed.
What effect would it have? The original post didn't state whether the 97 in question was a manual or an automatic, but let's say the car is an A4 with the 3.15 axle. If you went to the manual ratio, 3.42, given the stock tire size you'd, loose 12 mph. If you went to the 3.73 aftermarket ratio, you'd loose 24 mph. If you go to the 4.10, it's 35 mph. Does that make a difference? It depends on what you want to do with the car? Obviously, if all you do is drag race, it won't. On the other hand, if your a track day road racer it will. Will it affect mieage? Definitely.
As to how long does it take to change the rear axle assembly? Well, the lift you have will make it easier. Changing the rear axle assy requires removing the entire driveline from the car. Additionally, you must have some method or device with which to support the torque tube/transaxle assy during removal.
Is this impossible for the DYI? Of course not. Will it take a lot of time and effort? Yes. With the lift and the proper tools, but considering you may have never pulled a C5/C6 tube/transaxle assy and that could slow the process a bit as you learn, I'd say you're looking at couple of days work. I strongly suggest you purchase a factory service manual before you tackle the job.
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- #14
forkliftman79
Well-known member
I have a factory service manual. The car has an automatic in it. Maybe I will just leave the thing alone. Thanks for your input guys.
edram454
Well-known member
a4 with 3.42
having a a4 with a 3.42 i can tell you it is a significant difference in performance and gas mileage. I also installed supercharger and cam and rev kit so the car can go to 7k. it makes 525 to the wheels and traction is a problem. when you launch you are spinning and when you get into boost (at any speed) you will start spinning so the car becomes dangerous. it certainly needs drag radials but like Mr. Halverson said I will need to replace some parts with hardened pieces..transmission, axle shafts, trans and rear brace and hardened gears. with those upgrades this car will launch like a rocket and stay planted. the 3.42 is worth the expense if you just want to get off the line quicker. it should take 4-6 hours to do the complete swap. I actually got my 15k mile rear end for 200 bucks!! It looked brand new. Look for deals.
having a a4 with a 3.42 i can tell you it is a significant difference in performance and gas mileage. I also installed supercharger and cam and rev kit so the car can go to 7k. it makes 525 to the wheels and traction is a problem. when you launch you are spinning and when you get into boost (at any speed) you will start spinning so the car becomes dangerous. it certainly needs drag radials but like Mr. Halverson said I will need to replace some parts with hardened pieces..transmission, axle shafts, trans and rear brace and hardened gears. with those upgrades this car will launch like a rocket and stay planted. the 3.42 is worth the expense if you just want to get off the line quicker. it should take 4-6 hours to do the complete swap. I actually got my 15k mile rear end for 200 bucks!! It looked brand new. Look for deals.
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