Building my 8.8 explorer rear diff
 

I plan on upgrading my rear differential to the ronin kit 8.8 explorer differential upgrade. The unit will be used so I plan on rebuilding it as much as possible. I plan on using this for street, drag and MAYBE some road racing / track racing but mostly street+drag.

Visiting sites like Summit and Jegs i see there are numerous upgrade possibilities for the diff. What should I consider? What are the pros and cons?

Also, is it ok to powder coat it i read that can mess with the cover mating surface somehow????

Thanks,

The 8.8 gives you basically any gear option you would want, so consider if you'd like shorter or longer gears because now is the time to change it. Depending on what Explorer diff you get, itl'll either come with 3.55s or 3.73s. You also have several differential options. The stock explorer diff will either be open or have Ford Trac Lok. The cheapest option is to put a set of new clutches in a Trac Lok diff. I went with the Eaton Truetrac. It's a helical-type diff, but is a lot stronger than the FD's torsen diff. I'm making close to 700wtq and haven't had any issues with mine. It's nice an quiet on the street and puts power down when you ask it to. It's also drives way straighter than my OEM TII LSD did when the tires are spinning.

I really don't know what type of gearing I should go with. I see so many options. What is the best street/drag type? Im willing to sacrifice top speed obviously.

Also, how can i tell if it has a Ford Trac Lok?

You'll probably get better advice if you provide what transmission you're planning to run, what you're doing in the engine compartment (twins or single turbo, 20B or LS swap, etc.) and what size tires you're planning to run. Generally, the higher the gear ratio the harder the car will launch (assuming you can put the power down) but you'll run higher RPM's on the street.

Im on an EFR 8374 534whp 255/40/17 street tires, probably slicks on oem wheels for the strip

Currently stock FD trans l, planning on using the upcoming cd009 13b adaptor

We did a few posts near the end of that trans thread regarding rear gear selection relative to the usual OE trans/diff setups. Of course the rear gear for it is not going to be the most optimum with the OE trans depending on how long it will be before making that transition.

If you're going CD009 with a rotary, I'd use the 3.55s or 3.73s that come in the Explorer diff. That would give you roughly the same top speed in 1/2/3 as the OEM gearing with 4.1s, but with better cruising gearing in 6th. I'd almost consider going longer than 3.55s. I was making similar power to you when I still had the rotary, and 1st and 2nd gear were basically worthless with stock gearing. Having longer gearing would have made the car faster, but maybe a bit less driveable if you had to do lots of hill starts or traffic.

In that thread I concluded that the 3.45 could be considered for those who were already using the 3.909 rear OE automatic R&P. There are some in the 3.3x range too that would help to make the lower gears more usable without dropping the cruise OD rpms too low.