3.31 Gear change, 3rd time is the charm

[RBS550]

Thank you KOHR MOTORSPORTS, getting 3.31s wasn't as easy as I thought, but Dean at KOHR took care of me.
Now those of you that are counting. that's right this will be my 3rd gear change. I'm going to a 28" tall DR, so I really need this to keep close to where I am numerically with the 3.15s. I should be able to pick up a couple hundred RPMs at the big end with this gear tire combo.
So now you know what I'll be doing this weekend, I will update when I finish, how this can be done with jack stands and no special tools, other than a press to install the bearing, of course with plenty of pics.
Now I did find it interesting that the part# doesn't indicate 3.31s and the paperwork says 3.15s, but the casting has 3.31 in it and 43 teeth on the ring divided by the 13 teeth on the pinion confirms they are indeed 3.31s and as a bonus it comes with the one bear I need to install the gears, the other is not necessary...SWEET

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[notstok5.0]

I'm definitely in for updates. I just returned some 3.55 gears I bought because everything I saw online made this install look like more than I was willing to tackle.

 

[1320']

There ya go....that's the stuff!

 

[RBS550]

I'm definitely in for updates. I just returned some 3.55 gears I bought because everything I saw online made this install look like more than I was willing to tackle.

Here's a link to the post where I installed the 3.73s, I eventually went back to 3.15s because I was going into 4th about 300' from the finish line and didn't gain anything in 60' and I believe that's because the Circle D converter makes up the difference. Back then I could not locate 3.31s, Ford Racing is not going to offer them, they have to be purchased as a stock replacement part.

http://www.mustang6g.com/forums/showthread.php?t=27136

 

[2015 Silver GT]

Interested in your results. I would hope you see a tenth or two for gains.

 

[RBS550]

Okay the 3.31s have found their home.
From previous changes I already know I need .038 under the pinion bearing.
You will also see I always use heat when working with press fit items. Most of the time it will go together by hand or at least very little effort with the press. You heat up the outer item and chill the inner item.
You can see my home made flat stock, this makes easy work with the pinion nut, removal and install.
Initially my backlash was too tight. Fortunately the drivers side shim was .004 thicker than the passenger side, so a simple swap was made from one side to the other, now the backlash is in spec.

 

[Road Dog]

Awesome!

 

[notstok5.0]

great job, thanks for posting this!

 

[IvanCRF]

RB, that looks like the Harbor Freight 20 ton press. If it is, how do you like it? I received an ad where it will be on sale soon for $159 and am considering it.

 

[RBS550]

RB, that looks like the Harbor Freight 20 ton press. If it is, how do you like it? I received an ad where it will be on sale soon for $159 and am considering it.

That is Harbor Freight but it’s actually 12 ton. It works fine. Sure it’s not as robust as a name brand and the bolting has no markings on them indicating Grade.
The Harbor Freight bearing separator definitely needs better bolting as they tend to bend when trying to remove a bearing. This is where some localized heating on the bearing is a big help. But the only time you need to remove the pinion bearing is to find out what shim is underneath. If you do remove a pinion bearing and it gets damaged in the process, save the inner race as this comes in handy for pressing the new bearings on.
Back at home I have mine on a little wheeled platform so I can roll it around easily and put it back when I’m done. Of course it’s top heavy so I move slowly with caution.
The good thing about a press is you can always replace the jack if it goes bad.
Now to just to be clear I know this is Made in China stuff and I prefer USA, but for a DYI this will do what you need and obviously 20 Ton will do even more.
Just always use caution with a press, because when something decides to shoot out, it comes out fast and it’s usually a dense object that can do a lot of damage.

 

[RBS550]

These pics are to to show a fellow M6G member how little you have to remove to get the center section out when using DSS Half Shafts or similar.
Because I have BMR solid bushings, the front bolt hits the gas tank before its out of the center section, so I always make my gas is almost empty to lighten the tank, I remove one bolt at a time on the gas tank straps to lower the tank just enough to get the bolt out, never are both gas tank strap bolts out at the same time but the one that is left in, is backed way out and I have a jack stand under the gas tank as backup.

 

[gsxr1300]

Thanks for the pics!

 

[RBS550]

No problem, I'll help in any way possible.
There are more ways to do things that I do, but it nice to get an idea of what lies ahead.

 

[NewTekBuzz]

Wow! Wouldn't have a clue

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