Gen IV 3 55 Gear Install

[Stealth78]

Hey guys, I know there have been multiple people that have posted about this and yes I have used the search function.... My Gen IV is the dreaded 2008. I just received my 3:55's and install kit and I'm wondering if anyone has documented the disassembly of the rear differential, specifically the stub axle removal. I will not be doing the gear install myself but I would like to pass along as much useful information or pictures to the guy that is going to do the install. I have read that there is a square c-clip on the 2008 model that is a nightmare when trying to remove the stub axles. Anyone have a picture of these? Any helpful tips will be greatly appreciated! Looking forward to getting these gears in! Thanks!!!

[slowhatch]

[Rmj]

Alex (Slowhatch) has the best documented removal I have seen so far...
https://driveviper.com/forums/thread...l=1#post127288

Go to post 198

As I posted before, his posts convinced me to send it to Unitrax; they broke my diff getting them out (after forewarning me the axles or diff may break).

[Stealth78]

Ya I already read through that thread, cried a little, then realized that was two years ago and had hopes that someone has identified some way better to approach this. How is it so impossible to get this apart? Please tell me somebody has discovered a way to get this apart!

[Stealth78]

Does anyone have a picture of one of the c-clips/snap rings?

[Steve M]

Well, this is how they changed it on the Gen 5:

https://driveviper.com/forums/thread...ghlight=easier

You can see the clip in the Gen 5 differential has a circular cross-section. The 2008 cars have a square cross section circlip, and the stub axles don't have the tapered groove like they show in those pics. They changed the stub axles too in 2013...now instead of a male splined output, they have a bolt-together flange for the axles/CVs. This makes it easier to get everything apart, and also gives you something to grab onto when you need to pull them out to do a gear swap. Sucks to be us I suppose.

Here's my solution:



If you can't beat 'em, join 'em. For the price of a Wavetrac, I now have a complete Gen 5 differential assembly. I'll still need to swap out the Gen 5 stub axles for a set of Gen 4 stubs, but I ain't gonna have to worry about whether or not I'm going to break something trying to get the 3.07s out. Plus, I can switch back to the stock assembly for 1/2 mile events where the 3.55s are not desirable.

Not a cheap solution, but based on the experience of others, you could end up paying way more if something does break trying to get the stock one apart.

[viperBase1]

Here's my solution:



If you can't beat 'em, join 'em. For the price of a Wavetrac, I now have a complete Gen 5 differential assembly. I'll still need to swap out the Gen 5 stub axles for a set of Gen 4 stubs, but I ain't gonna have to worry about whether or not I'm going to break something trying to get the 3.07s out. Plus, I can switch back to the stock assembly for 1/2 mile events where the 3.55s are not desirable.

Not a cheap solution, but based on the experience of others, you could end up paying way more if something does break trying to get the stock one apart.

If that works..GENIUS!

[Stealth78]

Well, this is how they changed it on the Gen 5:

https://driveviper.com/forums/thread...ghlight=easier

You can see the clip in the Gen 5 differential has a circular cross-section. The 2008 cars have a square cross section circlip, and the stub axles don't have the tapered groove like they show in those pics. They changed the stub axles too in 2013...now instead of a male splined output, they have a bolt-together flange for the axles/CVs. This makes it easier to get everything apart, and also gives you something to grab onto when you need to pull them out to do a gear swap. Sucks to be us I suppose.

Here's my solution:



If you can't beat 'em, join 'em. For the price of a Wavetrac, I now have a complete Gen 5 differential assembly. I'll still need to swap out the Gen 5 stub axles for a set of Gen 4 stubs, but I ain't gonna have to worry about whether or not I'm going to break something trying to get the 3.07s out. Plus, I can switch back to the stock assembly for 1/2 mile events where the 3.55s are not desirable.

Not a cheap solution, but based on the experience of others, you could end up paying way more if something does break trying to get the stock one apart.

Steve, in regards to Mark's post in the link that you supplied - "GenV Differential gear changes will be easier then the GenIV with the return of rounded clips and a taper on the release edge of the stub shafts.", has it clearly been identified if this is a 2008 model year issue or is it all Gen IV's? Mark makes it sound like it's all Gen IV's. If it is indeed a 2008 issue only does anyone know exactly when they changed the design in 2009? The reason I ask (And I realize this is a slim chance) is because my car is a late 2008 MY build.

[Steve M]

Steve, in regards to Mark's post in the link that you supplied - "GenV Differential gear changes will be easier then the GenIV with the return of rounded clips and a taper on the release edge of the stub shafts.", has it clearly been identified if this is a 2008 model year issue or is it all Gen IV's? Mark makes it sound like it's all Gen IV's. If it is indeed a 2008 issue only does anyone know exactly when they changed the design in 2009? The reason I ask (And I realize this is a slim chance) is because my car is a late 2008 MY build.

I don't know, and I'm not sure anyone outside of one of the original powertrain engineers would know the answer to that question. Mark's worked on enough that he would probably have a good idea just based on the ones he's seen.

In my mind, it's the same problem as the hollow vs. solid CV/axle question...when researching the problem, I saw some information that ALL 2008+ cars got the solid shafts, but that was obviously not true. The next hypothesis was that it was limited to the early build cars, but no one could give a cutoff date as to what constitutes an "early build". At the end of the day, it's what was in the parts bin at the time your car was rolling down the assembly line. Unfortunately, the circlip and/or tapered stub axle issue isn't nearly as easy to tell since the parts are internal to the differential housing, and you won't find out until you try to remove them. Realistically (and unfortunately), that's the only way you'll know with this one.

[Stealth78]

Been ridiculously busy, finally starting to coordinate my buddy's shop with the lift and the axle/driveshaft builder to attempt to minimize soaking up a bay in my buddy's shop for to long. Hopefully this will come together without being too much of a pain (or should I say "come apart"). Another question I have, where does this car determine speed? Do I need some type of recalibration for my speed once the new gears are in?

[Steve M]

It's done with the ABS sensors...no recalibration needed.

[Stealth78]

It's done with the ABS sensors...no recalibration needed.

Awesome thank you!

[William craun]

SO may i ask the advantage of this differential swap in the Gen4 to 3:55 and how differs in comparison to just changing that transmisson .80 gear?

[Steve M]

SO may i ask the advantage of this differential swap in the Gen4 to 3:55 and how differs in comparison to just changing that transmisson .80 gear?

With the differential gear swap, you get the mechanical advantage of the numerically higher gear ratio in all gears. With the 0.80 5th gear, you only get the mechanical advantage in 5th gear.

It all depends on your driving style, and if you track it, the layout of the track you frequent most. With 3.55s, more torque goes to the tires, so it is easier to have wheel spin in the lower gears (especially 1st and 2nd gears). You also run out of gear sooner, so you'll be shifting more.

[efnfast]

Are there any companies that sell a 2008 differential with gearing done already so you can either keep your stock one if you want to reuse it down the road or do a core swap and get some money back?

I've been thinking about doing it but I don't want to send my differential out and be down for an unknown period of time, nor are there any shops I'd trust here to do it.

I'd happily pay a premium to just be able to drop it and put in a modified one same day.

[Steve M]

https://driveviper.com/forums/thread...ial-in-a-Gen-4

[efnfast]

Is there a noticeable difference between 3.07 and 3.55? I remember when I did 4.10s in my mustang (I think 3.23 was stock) and it was like bolting on 100hp. 3.55 doesn't seem like it would be alot for probably $5k all in today.

[J TNT]

3.55’s make 5th and 6th usable. And is noticeable. Unless you are making 750hp then stick with 3.07’s.

[Old School]

Is there a noticeable difference between 3.07 and 3.55? I remember when I did 4.10s in my mustang (I think 3.23 was stock) and it was like bolting on 100hp. 3.55 doesn't seem like it would be alot for probably $5k all in today.

3.55's have 15% more torque multiplication than 3.07's, so it feels like your engine's torque (not horsepower) went up by the same percentage, say 500ft-lbs feels like 575ft-lbs.

[Joel]

Are there any companies that sell a 2008 differential with gearing done already so you can either keep your stock one if you want to reuse it down the road or do a core swap and get some money back?

I've been thinking about doing it but I don't want to send my differential out and be down for an unknown period of time, nor are there any shops I'd trust here to do it.

I'd happily pay a premium to just be able to drop it and put in a modified one same day.

JonB fixed me up with a Gen IV differential for my Gen III complete with a 3.55 gear installed. I got my differential and sent the other back the next day. It is not a hard swap but if you don't have a rack it could be a lot harder. I think Unitrax built it for him as that is who I sent my old one back to. Gen IV are stronger than Gen III parts. There was a 500 mile break in period but it was the best mod I have done to the car. It wasn't cheap but reasonable.

[13COBRA]

Is there a noticeable difference between 3.07 and 3.55? I remember when I did 4.10s in my mustang (I think 3.23 was stock) and it was like bolting on 100hp. 3.55 doesn't seem like it would be alot for probably $5k all in today.

I'd sell you a whole rear differential with 3.55s for $4500 lol

[Stealth78]

I will say that this was my favorite mod, and yes 3:07 to 3:55 was VERY noticeable! Unfortunately I totalled my car last October. My end goal was to swap out 5th and 6th gear to .80 and .65 (I believe) respectively and then in my eyes all of the gearing would have been perfect! To make up for the added traction issue I was going to run R888R's (which are amazing on my HC Redeye) which would have tied everything together. My car made 570whp on a very conservative Mustang dyno, it was probably making around 675 - 700 at the flywheel (exhaust, hi-flo's, GenV intake, under drive pulley, HP tuning).

[William craun]

I will say that this was my favorite mod, and yes 3:07 to 3:55 was VERY noticeable! Unfortunately I totalled my car last October. My end goal was to swap out 5th and 6th gear to .80 and .65 (I believe) respectively and then in my eyes all of the gearing would have been perfect! To make up for the added traction issue I was going to run R888R's (which are amazing on my HC Redeye) which would have tied everything together. My car made 570whp on a very conservative Mustang dyno, it was probably making around 675 - 700 at the flywheel (exhaust, hi-flo's, GenV intake, under drive pulley, HP tuning).

So, what advantage would doing the transmission swap have given with the diff swap?

[Stealth78]

So, what advantage would doing the transmission swap have given with the diff swap?

It would have further optimized 5th and 6th gear. One of my biggest complaints in GenIII and GenIV cars (T56 and TR6060) is the enormous gap between 4th and 5th gear (ratio wise). If you watch videos of Viper's racing on highways (off road highways of course!) they typically hold their own very well, but up around 150mph (top of 4th gear with 3:55's) they get walked by inferior cars due to the 1.00 to .74 ratio change that occurs from the 4th to 5th gear shift. By swapping out 5th to .80 and 6th to .65 (or .68... I forget) it helps eliminate that feeling of a massive loss in power by keeping the rpm's in an optimal range.