Broken diff bolt?

[Clint81]

I don't know for sure yet but I am thinking I may have popped a diff bolt this past weekend. Just a mistake on my part, thought I was in neutral but let out the clutch way too fast in first and gave the drive train a real shock. Now when I transition from backing up to moving forward, I get a few clicks/clunks from under the car. My Ranger made the exact same sound when my transmission mount bolts were broken.

Anyway, I'll get the car up on ramps to look, but how difficult is removing a broken diff bolt? How easy is that to see without a lift? Steeda and BMR say it's a 4 hour job to replace all the bolts with upgraded units. Does that sound about right?

Should I just take it to the dealer and maybe let them diagnose and fix it under warranty? Successful trips to local dealership service departments are about 1 in 4.
I'm not afraid of working on the car but I don't want to make a problem worse that now requires a tow to the dealer.

What would you do?

Edit 1: would this be a "drive carefully" or "don't drive at all" condition?

Edit 2: edit 1 is a stupid question and should be ignored

Thanks all

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[Coastal-Mach]

I would at least take it to the dealer for an evaluation, play dumb and tell them it is making a noise.

Sometimes a broken bolt can really be a pain to get out and repair, especially if you are on your back. Having a lift is a different story. I would hope that didn't break a bolt, during your description of what happened.

If that's the case, you will never be able to dump the clutch for fear of breaking something.

Good luck and keep us posted on the findings.

 

[Cobra Jet]

Also check the driveshaft guibo and make sure it didn't tear. There's been a few threads on here with damaged guibos and even a newer thread with the DIY to repair it.

 

[Clint81]

Thanks for checking in guys. I know it's all purely speculative at this point so I'm just considering my options. That's the first I've heard of the driveshaft guibo so I'll be sure to look at that too.

 

[murick]

There is a note in a user manual that you should not shift into the 1st gear when driving faster than 15 mph (or such), otherwise it will damage the clutch. They do not say how though.

Interesting detail about this statement is that it is a kind of definitive. They do not say "may" or "could", just "it will".

 

[Paul McWhiskey]

Have you determined that it is just a broken bolt? Or perhaps an ear on the diff housing? Hopefully it is only a bolt.

I did the upgraded bolt kit on mine, and it did not take 4 hours, however I did it along with cradle lock outs and some other changes. Driving it may cause more damage. Were it me I would have it flat bedded to the dealer if that is what you decide to do with it.

 

[NGOT8R]

We’re you sitting still when you let the clutch out too quickly in 1st gear and the car bucked/lurched forward or we’re you driving? If you were sitting still, there shouldn’t be any damage caused. The noise you’re hearing sounds like drivetrain backlash. You can confirm this my rotating the driveshaft left to right and if you hear a clunk, it’s normal.

 

[WD Pro]

I hope you haven’t joined my club …

That’s the left side, but the right side also has nibble marks :

2020 car, standard PP1 spec including rubber, never been on a strip, never used launch control - I normally just roll into it but I can get through the 1st to 2nd shift pretty quick …

That piece of stud is well stuck in there. Due to that and the fact that the right hand side thread doesn’t look great, I’m waiting on a new rear cover

Hope your situation turns out better than mine

WD

 

[Andy13186]

could be axle thrust washers

 

[Cobra Jet]

I hope you haven’t joined my club …

That’s the left side, but the right side also has nibble marks :

2020 car, standard PP1 spec including rubber, never been on a strip, never used launch control - I normally just roll into it but I can get through the 1st to 2nd shift pretty quick …

That piece of stud is well stuck in there. Due to that and the fact that the right hand side thread doesn’t look great, I’m waiting on a new rear cover

Hope your situation turns out better than mine

WD

I'm assuming by the location, there's absolutely no way to drill that out unless the entire rear IRS cradle is removed from the car, right?

 

[WD Pro]

Yeah the wheel well is in the way when everything is fully in place, you couldn’t get square onto it.

The bush is also quite thick that you would have to work through to get to the broken bolt.

The diff is currently out of the car awaiting the new rear cover

WD

 

[NGOT8R]

could be axle thrust washers

Maybe certain models had the thrust washers, but my 2019 Bullitt didn’t have them.

 

[Clint81]

We’re you sitting still when you let the clutch out too quickly in 1st gear and the car bucked/lurched forward or we’re you driving? If you were sitting still, there shouldn’t be any damage caused. The noise you’re hearing sounds like drivetrain backlash. You can confirm this my rotating the driveshaft left to right and if you hear a clunk, it’s normal.

Right, yes I was sitting still, foot on the brakes. Car didn't move and stalled out. What a stupid mistake! I was on the side of the road and in a hurry + stressed + distracted when it happened.
I will check driveshaft play once up on the ramps. Nothing determined yet.

 

[NGOT8R]

Yeah the wheel well is in the way when everything is fully in place, you couldn’t get square onto it.

The bush is also quite thick that you would have to work through to get to the broken bolt.

The diff is currently out of the car awaiting the new rear cover

WD

Are you upgrading to the through bolt kit when you reinstall the diff? Did you have severe wheel hop that led to the failure?

I was concerned about that happening to my car, seeing as how I knew I was going to be doing launches, so I upgraded to the following:

Steeda through bolt kit, black bushings, bushing supports, differential bracket, motor mounts, jacking rails and subframe braces.

 

[Cobra Jet]

Yeah the wheel well is in the way when everything is fully in place, you couldn’t get square onto it.

The bush is also quite thick that you would have to work through to get to the broken bolt.

The diff is currently out of the car awaiting the new rear cover

WD

Yea, when I first saw the rear diff bolts and bushings being used on the initial 2015 rollout - I thought the hardware used was cheap, too small and "fragile" for the amount of weight and drivetrain load transfers that would be absorbed...

IMO, the "ears" on the rear diff and the factory bolts/bushings being used are the immediate failure points when any type of shock is introduced on a launch. I mean, these areas are failing on some S550's where the car doesn't have drag radials and isn't launched from a sticky track.

The diameter of the bolts need to be much larger as well as the grade used to be even considered strong enough to support the weight and load transfers. The same can be said about the ears on the diff, they need to have more metal and be much thicker to prevent the "break off" where they commonly fail. I wonder if Ford even improved this area on the S650's? I mean it's been almost 8 years now that the S550 is being manufactured and you would think this area would have had some type of revision by now.

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