Diffy Stiffy fenfab explorer install SOLVED - Do not use the nuts provided.

I like many others purchase a 2023 Ford Explorer ST only to go on the forums and find out this differential is a possible huge problem.

Sooo I bought the Diffy Stiffy after watching a youtube video on the installation, how hard could it be?

WRONG.

The s*** they do not show you is that, in order to access the nut in the subframe after drilling the hole you need WRENCH fingers. NOBODY has WRENCH fingers or a wrench small enough to fit in two TINY holes.

So after trying to install it, drilling holes in the frame, removing the differential bolts, and being unsuccessful for two hours because I do not have wrench finger tips and each time I tried to hold the nut and screw the bolt, it was impossible.

I contacted Fenfab and they were like you just need a stubby wrench to fit in there and it was complete BULL. They shouldn't even sell the product with the nut. So I was pissed I just paid close to $200 for this brace that I cannot install.

Sooo I did some googling and solved it.

First I explored JACK Nuts, which basically think of it like a manual rivet, but it required a very large hole to be drilled

Second solution I explored was a Nut Rivet Tool, M8 specifically since the Fenfab comes with M8 bolts. I tried utilizing the smallest drill bit to make the hole bigger to insert the rivet, but ended up using the 1/2 drill but which worked perfectly.

https://a.co/d/dzroY75
*This link is now updated for steel rivets

I followed the instructions and now the brace is torqued on there, my rivets are installed and I am happy.

If you are doing this for the first time, I recommend drilling the initial holes first with the brace with the small recommended drill bit, then taking the brace off, and widening the hole with 1/2.

I also learned the hard way, when utilizing the rivet tool, compress the handle so that you can easily screw out from the rivet. I utilized pliers on the knob and it took forever for the first rivet.

Your welcome, you can now buy the Diffy Stiffy courtesy of my hard work. Just allocate another $22 for that rivet tool.

*Additional update, despite the comments on aluminum rivets, looked up the strength for each 5/16 or m8 rivet the upset load and ultimate load minimum is 1900 lbs and 4000lbs respectively for each rivet. So together the weight capacity is doubled and they can hold 2/3 +weight of the vehicle. The explorer st is 5500 lbs (got it weighed for commercial plates for my side business). So you’re safe with either option aluminum or steel. Steel strength is 2x what’s listed and your rear differential weighs 66lbs if you were to buy it brand new.

So fenfab is actually wayyy more than enough to hold a diff, and even more expensive options are even more overkill.

I mean…Brett has sold tons of those things and everyone else got them installed with the provided hardware so…

User experience is the crux of all sales, most people do installs, struggle, and give up and do not post about it to not look bad.

The group I run that deals with stuff like this would disagree.

I wouldn't trust that install at all. Looks light duty. Also, the diffy stiffy is not the one to get, regardless.

My post is to help others who have struggled after purchasing the product and couldn't return the item after drilling holes in it. It's a reinforcement for bad engineering and a solution for bad customer support.

Not like I am going to track the suv or drag it where heavy duty support is needed. Most people buy the explorer because they have kids like me and need the extra cargo space bmw, benz, volvo do not offer, and the power without the v8 MPG chevy/jeep, and want some fun after dropping off kids and picking them up. It is a explorer after all, not a m3 or mustang. It's meant for going straight on country roads and racing the Tesla 3/Y, x3, x5, and 3/5 series red light to red light.

Well you’re certainly entitled to your opinion…but trashing Brett won’t make you any friends…especially when everyone but you managed to get his support installed with the hardware it ships with. Brett is a huge asset to the ST community with some of the best customer support out there. Nobody can make everyone happy…and you appear to be the one guy he couldn’t.

....

Wait wait wait…I just looked at the link you posted. You put an ALUMINUM rivnut in there? And you’re telling people this is a “solution” to a problem? If I were you I’d delete this thread right now and just let everyone that saw this forget about it. lol

Good call out. I'll just reinstall steel rivets and pop out the aluminum ones it should take 5 mins. The point of the post is for feedback and to help others. It's even promoting the fenfab purchase. I am not here to trash people or, make friends. It’s a problem I identified in my install that i believe others would.

During their comparison video for the differential bushing inserts, JXB mentioned the FenFab brace was just as solid as the AWR and Steeda braces.

i think you mean the durometer measurements of the bushings used? Stiffy diffy is the only one Ive seen on a failed mount and the Stiffy Diffy was all bent to hell.

What year was this destroyed stiffy? The advantage I have is since its 2023 a lot of problems and parts have been reinforced and replaced due to earlier tsb.

At 18:52, Jay states in the video states it will likely be just as good as the other braces:

Did anyone notice they don’t install the stiffy?

They said they did not install it because the owner did not want holes drilled in the frame. The others require no new holes.

No one should buy a "diffy stiffy". Here's why

Another video talked about how without the brace or any brace, the diff would fall out and you could not drive it if the bolt were to fail from tuning and horsepower or from a crash, and it was good insurance to be able to drive it to the dealer after it failed. So if it's on, it really doesn't hurt. In fact, since the diffy held the entire diff together, it proves my point that it is strong enough.


Read on another forum there is a bolt upgrade but people had trouble taking off the bolt without a breaker bar if the car was not on a ramp/lift, but I have a 1/2 inch dewalt impact driver.

https://whoosh-motorsports.myshopif...me-duty-rear-motor-mount-bolt-set-explorer-st

I also learned I am not affected by this bolt breakage due to being 2023, bushings were updated, but I am going to still upgrade my single bolt.

I've been following this thread. I don't think anyone here is faulting you for installing a differential brace. What I think members are trying to suggest to you is that the one you have chosen leaves something to be desired.

A member in the High Performance Explorer ST group just posted he made 600+ passes with the stiffy diffy without issue and he's making 11.5 passes