[R0ot.Us3r]

So I decided to grab some video of whats happening. I understand this is a rubber bushing, so would you all consider the amount of deflection seen in the video normal?

This is me going up and down my drive way. House is higher than the surface street so there is a decline. The bolt moves up (diff moving down) when the car reverses, and down (diff moving up) when going forward.

I didn't notice the defined *CLUNK* I was hear the previous day, but this was recorded after the car sitting my my garage from around 6pm yesterday until around 9am today. I'm thinking things might be tighter because the body is cold (Cold expands, Heat shrinks)

PS: Another thing I'm realizing, I'm barely hitting the gas to move the car. If it moving this much with like 10% throttle input in Comfort mode....how hard is this thing slapping around in Sport w/ 80% throttle from a stop....

Diff Recording

[Bimma360]

This is great! Thank you for doing that. I have no idea what should be normal, honestly. If that happened under the most extreme conditions, I would say it is normal. But that’s not the case now is it hahaha.

Then you have someone like BrockDM with a 9sec car still on the stock bushing with no issues.

[will0621]

Seems like some play is normal with this type of bushing? this video shows a f10 comparing a cracked bushing compared to a new one (new one starts at 1:44).

I’m not an expert by any means but if bmw designed this to allow some play, would the solid bushing solution that’s been discussed possibly cause any issues down the line?

[R0ot.Us3r]

Yeah the difference in movement between the old and new IMO was negligible. Part of me wants to say "They're engineers, they know what their doing" but the other part of me just doesn't like it.

Does anyone know if the rear bushing on our vehicle are the same as the ones on the i30 X3s? I want to believe they would have beefed ours up, but I'm thinking its the same part...

I have a dog-bone bushing insert on my MK7 VW GTI, and outside of additional vibration felt when reversing, there has been no ill effect on the car and I've had it from new since '17. Is it a 503hp AWD heavy'ish SUV – no, but thats still a key bushing to control X-axis rotation on the motor.

[joebie3]

Bad ass video, really good view of the flex for sure.

This might be hard to explain or sounds stupid, but for bushings I look at it like this, each bushing is a fuse of some sort. The question in my mind is always, what does putting a stronger fuse in do, and how catastrophic is this fuse when it blows? It moves the fuse failure point somewhere else.

Problem with this bushing, is that when it fails, it's pretty spectacular in a bad way. :-|

[R0ot.Us3r]

I found this and i think this might actually be my issue

Can you do the transfer case calibration with ProTool?

[BrockDM]

Originally Posted by Bimma360

This is great! Thank you for doing that. I have no idea what should be normal, honestly. If that happened under the most extreme conditions, I would say it is normal. But that’s not the case now is it hahaha.

Then you have someone like BrockDM with a 9sec car still on the stock bushing with no issues.

While I do run the stock bushing, I change my bolt with every oil change if not sooner. I'm on bolt #4 within the last year and each one has been bent but not broken. It's merely a temporary fix but it's been working. I'm leaning towards a diff lock down kit from VTT vs going solid bushing. I don't want any added noise.

[R0ot.Us3r]

Originally Posted by BrockDM

While I do run the stock bushing, I change my bolt with every oil change if not sooner. I'm on bolt #4 within the last year and each one has been bent but not broken. It's merely a temporary fix but it's been working. I'm leaning towards a diff lock down kit from VTT vs going solid bushing. I don't want any added noise.

are you using a standard 14mm bolt or a new OEM one? I know its been noted that the OEM ones are thinner

[BrockDM]

Originally Posted by R0ot.Us3r

are you using a standard 14mm bolt or a new OEM one? I know its been noted that the OEM ones are thinner

I use Belmetric.com.

Bolt
https://belmetric.com/hex-bolts-10-9...H14X1.5X40FYLW

Nut
https://belmetric.com/steel-class-10...n-flange-nut/?

Washer
https://belmetric.com/hv-200-steel-h...=WFEHV14X44YLW[/QUOTE]

[R0ot.Us3r]

I have this already, awesome. So lift the rear, support the diff, remove and replace the bolt washer and nut.

Much easier than replacing the bushing and I’ll def feel better

[Kevin_The_Clean1]

Originally Posted by BrockDM

While I do run the stock bushing, I change my bolt with every oil change if not sooner. I'm on bolt #4 within the last year and each one has been bent but not broken. It's merely a temporary fix but it's been working. I'm leaning towards a diff lock down kit from VTT vs going solid bushing. I don't want any added noise.

This is great insight here & if this is what works well on yours, then this is surely a great alternative & solid solution. You have lots of track passes to prove that this bolt is getting bent overtime.

[Bimma360]

Originally Posted by BrockDM

While I do run the stock bushing, I change my bolt with every oil change if not sooner. I'm on bolt #4 within the last year and each one has been bent but not broken. It's merely a temporary fix but it's been working. I'm leaning towards a diff lock down kit from VTT vs going solid bushing. I don't want any added noise.

Thanks for the insight! Sorry I have been blowing you up with these question across multiple threads haha.

I didn't know about the VTT kit until you mentioned it. I just looked it up, and it looks great! I really like this idea. I wish they had more pictures or install instructions, as I want to wrap my head at how it it is NVH friendly. It looks to be a solid mount solution, in the sense that it does not allow any play in the diff. I haven't done a diff lockdown before on any of my cars so I am not familiar with the concept first hand.

[BrockDM]

Originally Posted by Bimma360

Thanks for the insight! Sorry I have been blowing you up with these question across multiple threads haha.

I didn't know about the VTT kit until you mentioned it. I just looked it up, and it looks great! I really like this idea. I wish they had more pictures or install instructions, as I want to wrap my head at how it it is NVH friendly. It looks to be a solid mount solution, in the sense that it does not allow any play in the diff. I haven't done a diff lockdown before on any of my cars so I am not familiar with the concept first hand.

Yea no problem. My hope was to see a few people install it before I make up my mind but I like the idea. Tony shared videos in the Facebook groups of the post install. The only nuance is you have to drill and rivnut the subframe to lock the brace in place.

My thought process was since all 3 differential bushings remain rubber, there shouldn't be any added noise. Vibration I'm not sure of...

[Bimma360]

Cool! I'll try to hunt down the videos in the Facebook group. I do still like the idea of the VTT kit.

[Bee Pee]

Originally Posted by BrockDM

While I do run the stock bushing, I change my bolt with every oil change if not sooner. I'm on bolt #4 within the last year and each one has been bent but not broken. It's merely a temporary fix but it's been working. I'm leaning towards a diff lock down kit from VTT vs going solid bushing. I don't want any added noise.

Makes sense to go with VVT bracket.

F8x series m car owners upgraded single rear bush mount to dual mount to spread the load and allow diff movement in subframe but with less excursion so to speak.

Even BMW saw the issue with single rubber rear diff mount bushings on F8x m cars by switching to poly bush single bush on later cars.

[x3mdustin]

Originally Posted by R0ot.Us3r

So I decided to grab some video of whats happening. I understand this is a rubber bushing, so would you all consider the amount of deflection seen in the video normal?

This is me going up and down my drive way. House is higher than the surface street so there is a decline. The bolt moves up (diff moving down) when the car reverses, and down (diff moving up) when going forward.

I didn't notice the defined *CLUNK* I was hear the previous day, but this was recorded after the car sitting my my garage from around 6pm yesterday until around 9am today. I'm thinking things might be tighter because the body is cold (Cold expands, Heat shrinks)

PS: Another thing I'm realizing, I'm barely hitting the gas to move the car. If it moving this much with like 10% throttle input in Comfort mode....how hard is this thing slapping around in Sport w/ 80% throttle from a stop....

Diff Recording

don't know about you , but my balls shrink in the cold and don't expand as you say and are hanging low in the heat and not high like you explained. heat expands the molecules and cold contracts them, that is why we heat a bolt to loosen it.......

[R0ot.Us3r]

Originally Posted by x3mdustin

don't know about you , but my balls shrink in the cold and don't expand as you say and are hanging low in the heat and not high like you explained. heat expands the molecules and cold contracts them, that is why we heat a bolt to loosen it.......

Ooooh, so water SHRINKS when it gets cold…
Busted frozen pipes are a lie folks

[M4Lou]

Originally Posted by Kevin_The_Clean1

This is great insight here & if this is what works well on yours, then this is surely a great alternative & solid solution. You have lots of track passes to prove that this bolt is getting bent overtime.

For those of us that have follow this rear differential bolt/bushing problem with great interest from an even greater distance - HAS someone made a urethane bushing alone?

[joebie3]

Me over analyzing the last few comments about expansion and contraction:

Originally Posted by M4Lou

For those of us that have follow this rear differential bolt/bushing problem with great interest from an even greater distance - HAS someone made a urethane bushing alone?

Yes, Ryan Morard who can be contacted on the forums. He makes the rear and the front two.

[AshtonPJT]

Originally Posted by M4Lou

For those of us that have follow this rear differential bolt/bushing problem with great interest from an even greater distance - HAS someone made a urethane bushing alone?

Yes I have one almost ready to release😁