FD Explorer 8.8 Diff Kit

[wickedrx7]

Ronnin 8.8 Review:

Design: You can read through this thread to see all the design changes they made, although it took longer than originally discussed, the extra time was well spent cause I think the design is great.  Although a bolt in option would have been nice, the weld in option had everything I wanted.  Compact design while offering the most durable setup on the market.  This kit also give you an amazing amount of room for exhaust routing.   

Quality of kit and components:
The overall quality of this kit is great.  The welds, laser cut plate and bent tubes is top notch.  The hardware, axels and boots look to be excellent quality as well. 

Two Problems that I encountered:
1) The weld on the bushing rings protruded above the ID of the bore which would have made it very hard to install the bushing.  This was a super easy fix, about 2 minutes with a sanding drum and it was clearanced.


2) The second problem was the actual fitment of the front cross member.  One of the upper mount was about 3/16” away.  After talking with Joel, he gave me a few tips: First, try to determine if it was binding somewhere.  I found that it was hitting some factory welds on the lower front.  I also took a very small amount off the ends of each bar to get it to sit a little lower and tighter.  I got all the gaps down to less than a 1/16”, actually the top one was nice a tight.
 Both of these issues are really not a big deal and fully expected with a kit like this.  I just want to give the most accurate feedback I can so potential buyers know exactly what they are getting.

So far I am very impressed with the kit.  Everything you will need is included, the quality is excellent and I think it is going to outperform any other kits/rear ends on the market. 
Here are a few more pics:

Initial fitment, notice upper left arm:


After clearancing and welding in ( I forgot to take pics of it tacked in.. DOH):

[mefarri]

Looks great to me.

[Skeltic]

Does the drive shaft that a person would have used to attach a t56 to a stock diff from a manual car, would it bolt right up or does it need shortening or is a longer drive shaft needed, plus mounting on the 8.8 ?

[digitalsolo]

That looks great.  Thanks for the review.

[Exidous]

I cannot tell from the pics but did you MIG or TIG it in. All I have is a TIG and gaps are a potential problem. I still have a lot of practice to go with my welding. :-/

[V8-rx7]

The driveshaft needs a different flange, on Jeff's car he just swapped flanges but depending on your driveshaft it might need to be shortened.

[frijolee]

Thanks for the review.  Figured I would add a couple notes that other folks have been running into.

--We've confirmed that folks do need to have a diff in place in order to tack weld the front cradle in.  That's needed to confirm that the cradle is landing correctly.  If you have an angle finder you want to shoot for the pinion flange to be setup about 2.5 deg off from vertical with the horizontal position of the overall subframe defined by the flat landing surfaces at the top (you shim the whole subframe on a table until that's flat).  I took some pictures I'm now adding to the instructions.

--Users will need to bend down the brake bracket slightly during fitment.  This was missed by one user and was causing the cradle to sit slightly twisted which made edge fitment of one of the tubes poor.

--We are using factory fitment rear isolators (you pick the style: poly, delrin or whatever).  We're trying to get the diff as far rearward as possible for factory like halfshaft angles, so you may need to sand off the corner of a bushing depending on style.  The weld protruding into the bore (even if only slightly) was an error but we'll look for that going forward.

--We did have an in-person get together that involved three Ronin front cradles and three subframes so we have a pretty good handle on the tolerances involved.  Coming out of that fitment session we choose to go back and optimize our welding fixture.  We're adding just a touch of length to two of the tips and also shifting that upper left bar you pointed out higher.  It appears to have pulled down slightly in the first article which was then replicated on the first batch.  It shouldn't make a difference but since we're revisiting the fixture anyways we've made it as perfect as we can.  Future users should be aware that we're making this a tight fit to avoid gaps before welding.  This may mean that depending on tolerances and OEM weld boogers you make need to grind tips slightly.  Still it's easier to remove material than add it so we made the call.

Finally, a big thank you goes out to all our testers. This is both for your patience getting the design right in the first place and then working through install details to be sure we had this nailed.  Keep those pictures coming in.  We're adding the best ones to the install instructions.

We are sold out of the first batch, but we're well into production on the next one.  The full kit is officially up for sale on the Ronin website.   
http://www.roninspeedworks.com/index.php?route=product/product&product_id=88

-Joel (for the Ronin crew)

[wickedrx7]

I think adding length is a great idea, I think most people should be able to lightly grind each end to get it to fit perfectly. 

Should I be concerned that I didn't set my pinion angle? I will go back and measure once I get everything back together... but there isn't much changing it now...

[frijolee]

I think adding length is a great idea, I think most people should be able to lightly grind each end to get it to fit perfectly. 

Should I be concerned that I didn't set my pinion angle? I will go back and measure once I get everything back together... but there isn't much changing it now...

It's worth checking under the car to be validate, but we fixtured this thing well enough that you should be damn close already.  Worst case you can shim the front down by 1/8" or grind some on the diff bushings to raise it slightly.  There's always going to be a little car to car variation based upon which engine/trans mount system you were using.  There's no single number that's perfect, pinion angle is all about trying for equal and opposite. 2.5 deg away from level is a good position for most folks.

[largeorangefont]

Remember you can add or subtract shims on the trans side or the motor mounts to adjust the angle as well.

[frijolee]

FYI: uploaded an overview, pics and info to the first post for future reference.

[quinns]

Shimming the front of the diff is easy as hell because the back is on a pivot. Just grind out more of the front rubber mount or add a shim.

The length of the upper tube on the right side of the car could be up just a hair but its seriously so close its not a big deal.

This kit worked out real great for me. Experienced same problems as wickedrx7 to a T. All easy to overcome.

I've bought shit that was supposed to be "bolt in" that gave me waaay more grief than anything in this setup.

Thanks for making such a great kit!

[markfluko]

How does this look for measuring? I wasn't sure where to get the best flat surface for the angle finder on the diff, but I used the boss/ledge on the side of the diff.

Does everything seem to be done in a correct manner?

Shimming subframe to where it is flat



Left side and right side, got them dead center





Calibrate angle finder on the flat portion of the top of the subframe.



Shim until 2.5 degrees pointing up





This showed me that I need to shave just a little bit more off the the diff cover. I don't want it ever vibrating and making contact.



Assuming I did everything correctly... I will just need to tack up the brace and double check everything.

[V8-rx7]

I measure it off the pinion flange, I think that is the most accurate point of measurement.

[largeorangefont]

I measure it off the pinion flange, I think that is the most accurate point of measurement.

Yes, always use the pinion flange.