[GetShwifty]

So my independent shop just told me my 2016 m235i with only 33,700 miles has a cracked differential bushing (rear) and the repair comes with $1000 of labor aaand I need a complete set of rotors and pads since the rotors weren't turned when the previous owner had the pads replaced. Hot and dry Phoenix weather might be be to blame for the cracked rubber.

First off, a cracked/torn diff bushing at 33k seems really early. Reading about it I should hear a clunk or have trouble shifting, but the only thing I remember noticing is very occasional (<1/month) difficulty getting it in 1st at a light. Should I get a second opinion on it?

To make lemonade with these lemons, while they have it up and the relevant parts removed, what else could I get done to save some money? It is my daily but I have done autox in the past and hope to get a track day or two in. I am already planning on swapping the stock wheels, thinking square 18x8.5 with 235/40 MPS4S tires once I figure out offset/fitment and commit on wheels, Apex/VMR/etc.

I have seen positive reports on Delrin/PU diff bushings, but am unfamiliar with what access is needed for other parts and where labor can be combined.

Any recommendation on rotors and pads for street/track use?

My personal budget isn't too restrictive, but the wife approval rating is a bit important as I haven't moved from my temporary ~Mr. COVID school at home dad after getting dropped for budget cuts in July~ back to a real job and she's earning all the money right now . Hence the interest in saving labor costs. The new square wheels are partially motivated to save money on tires by allowing front to back rotation

[GetShwifty]

So the oil pan gasket is also supposedly leaking and I just learned that it requires/gives access to front suspension bits with its $854 of labor:

https://www.2addicts.com/forums/show...34&postcount=6

the overall basic design of bmw's has been the same forever. to pull the pan and change the gasket you'd have to support the motor top side, then remove the subframe which has at a minimum the steering rack and control arms attached. not to mention the motor mount on it. they probably can't justify the work for the amount of seep.

So add that to the list of possible places to save labor on suspension upgrades.

[aerobod]

The oil pan gasket on the N55 is the least likely of 3 places to leak, if oil looks as though it is coming from that gasket. The most likely is the oil filter housing gasket (easy fix), followed by the valve cover gasket (a bit more work), then the oil pan (the most work). To properly diagnose where the problem is, it is worth having any oil cleaned off the outside of the engine then carefully monitoring for seepage from the valve cover and below the oil filter housing, especially at the back of the engine as the oil runs down on to the oil pan.

[overcoil]

Just today I noticed that my oil pan gasket is leaking.

Oil filter housing gasket replaced last year and that ares is clean.

It could be a rear main seal leaking. But I this point I'll do the oil pan gasket, clean everything. watch a slight weeping at the valve cover gasket.

[dradernh]

Originally Posted by GetShwifty

First off, a cracked/torn diff bushing at 33k seems really early. Reading about it I should hear a clunk or have trouble shifting, but the only thing I remember noticing is very occasional (<1/month) difficulty getting it in 1st at a light. Should I get a second opinion on it?

To make lemonade with these lemons, while they have it up and the relevant parts removed, what else could I get done to save some money? It is my daily but I have done autox in the past and hope to get a track day or two in.

I am already planning on swapping the stock wheels, thinking square 18x8.5 with 235/40 MPS4S tires once I figure out offset/fitment and commit on wheels, Apex/VMR/etc.

I have seen positive reports on Delrin/PU diff bushings, but am unfamiliar with what access is needed for other parts and where labor can be combined.

Any recommendation on rotors and pads for street/track use?

...the wife approval rating is a bit important as...she's earning all the money right now . Hence the interest in saving labor costs.

The new square wheels are partially motivated to save money on tires by allowing front to back rotation

1) I'd have at least one more shop take a look at the bushings as well as generally looking the car over for things that need replacement, things that would be nice to replace now, and those that can be seen to need replacement at a general point in the future.

2) An LSD makes all the difference in our heavy, powerful cars, both on the street and at autox/track events. Those and stiff rear subframe bushings go together like mom and apple pie. I went with Turner's aluminum bushings and in terms of daily comfort don't feel I made any meaningful compromise where street driving is concerned.

3) Others may be able to offer their personal experiences, but from what's been posted about the MPSS model I don't think MPS4S will hold up very well to track work, especially if you don't introduce a fair amount of negative camber. This is somewhat dependent upon the track, its surface, and how hard you lean on the car, but it's only a Max Perf Summer tire.

4) I believe the diff comes out and goes back in when the subframe is removed for bushing replacement. Labor-wise, that makes it the time to upgrade the diff.

5) BMW rotors or the equivalent OEM units. Pads are an individual thing, but the stock pads and so-called street/track pads don't hold up well to track use. I can't speak to autox use. If you're going to the track, I'd recommend a genuine race pad. They make a LOT of noise on the street, so if that's a show-stopper the fall back is to swap pads before and after each track event. Don't forget to upgrade your brake fluid to something that can handle the highest temperatures, as your stock braking system is going to get extremely hot no matter what you do to help it in the way of pads and fluid.

6) Been there, done that. It sounds like you're on the right track, but still...don't screw it up!

7) A set of dedicated performance wheels and tires might be your best bet. That's if you can afford it, and it's not too inconvenient to manage. Square Extreme Performance Summer tires on square wheels would go a long way to getting the most out of both the car and the tires.

[GetShwifty]

Originally Posted by dradernh

1) I'd have at least one more shop take a look at the bushings as well as generally looking the car over for things that need replacement, things that would be nice to replace now, and those that can be seen to need replacement at a general point in the future.

I'm gonna have different, race oriented shop I've used take a look at it, hopefully tomorrow.

2) An LSD makes all the difference in our heavy, powerful cars, both on the street and at autox/track events. Those and stiff rear subframe bushings go together like mom and apple pie. I went with Turner's aluminum bushings and in terms of daily comfort don't feel I made any meaningful compromise where street driving is concerned.

Really would love to get the LSD for the better out of turn performance, and to have a little more sideways fun I've read quite a variety of different opinions on the NVH with solid bushings, subframe has more of an NVH impact than diff mount if I remember correctly, so I'm not sure what I believe. The shop it is at now warned me about significant NVH changes, specifically drivetrain noise for the diff bushing. What changes did you notice? Anyone else out there with input on this?

3) Others may be able to offer their personal experiences, but from what's been posted about the MPSS model I don't think MPS4S will hold up very well to track work, especially if you don't introduce a fair amount of negative camber. This is somewhat dependent upon the track, its surface, and how hard you lean on the car, but it's only a Max Perf Summer tire.

Yeah... I'm not sure I can justify a whole 'nother ~$1400-$2000+ for another set of wheels and tires for a few HPDE events, but I understand that it is definitely the way to go... I've thought about camber with plates or something... This is the part that really gets me stuck, especially combined with choosing tire and wheel sizes and offsets.

4) I believe the diff comes out and goes back in when the subframe is removed for bushing replacement. Labor-wise, that makes it the time to upgrade the diff.

Yup

5) BMW rotors or the equivalent OEM units. Pads are an individual thing, but the stock pads and so-called street/track pads don't hold up well to track use. I can't speak to autox use. If you're going to the track, I'd recommend a genuine race pad. They make a LOT of noise on the street, so if that's a show-stopper the fall back is to swap pads before and after each track event. Don't forget to upgrade your brake fluid to something that can handle the highest temperatures, as your stock braking system is going to get extremely hot no matter what you do to help it in the way of pads and fluid.

I see M performance rotors (or even whole brake package) on bimmerworld.com for essentially the same price as my quote, should I go for those? Don't have the car now and don't remember if the front rotors are already the larger 370mm or if they are the standard 340mm.
For the street/track pads, do you mean they wear quickly or more in the moment issues like overheating?

6) Been there, done that. It sounds like you're on the right track, but still...don't screw it up!

Is this regarding my comment on wheels? I went down the rabbit hole back in October but didn't come up with an answer and have been putting it off since. I hate how tight the wheel wells are and how many variables go into fitment for the m235i!

7) A set of dedicated performance wheels and tires might be your best bet. That's if you can afford it, and it's not too inconvenient to manage. Square Extreme Performance Summer tires on square wheels would go a long way to getting the most out of both the car and the tires.

Is it insane to daily drive something like the ADVAN A052?

I see just now that you also responded to my other post in the general forum, I'll respond to that one later. Sorry for the rookie cross posting.

[dradernh]

Originally Posted by GetShwifty

I've read quite a variety of different opinions on the NVH with solid bushings, subframe has more of an NVH impact than diff mount if I remember correctly, so I'm not sure what I believe. The shop it is at now warned me about significant NVH changes, specifically drivetrain noise for the diff bushing. What changes did you notice?

I see M performance rotors (or even whole brake package) on bimmerworld.com for essentially the same price as my quote, should I go for those? Don't have the car now and don't remember if the front rotors are already the larger 370mm or if they are the standard 340mm.

For the street/track pads, do you mean they wear quickly or more in the moment issues like overheating?

Is this regarding my comment on wheels?

Is it insane to daily drive something like the ADVAN A052?

I've noticed no increase in NVH to speak of from the solid subframe bushings i had installed. As always, YMMV, but I doubt it would vary by much.

Your front rotors are 340mm. You could try the M Performance Brake Kit with the 370mm front rotors, but remember that you'll still end up paying to install it unless you do it yourself or get a friend to help you do it. I'm not convinced it will make all that much difference. Bimmerworld would certainly be able to advise you both thoughtfully and honestly. Ask them if you're likely to discolor the calipers on the kit at the same rate that you're likely to discolor the blue Brembo calipers you have now. That will give you some idea of how much more heat capacity the 370mm rotors have.

For the street/track pads, I mean they'll not hold up very well due to overheating. That heat will be transferred into your brake fluid. Race pads have much higher heat capacities.

No, it was in response to your comments regarding your better half: "...the wife approval rating is a bit important as...she's earning all the money right now . Hence the interest in saving labor costs."

Extreme Performance Summer tires tend to be noisy to the point where most drivers don't care for them on the street. I'm using a Max Perf Summer tire on the street because I don't want to listen to the noise of an EPS tire. The A052 is the EPS tire I gave a great deal of thought to running on the street. You might try asking in the Tires section if anyone running an EPS tire on the street can comment on their experiences with them. One thing they'll likely mention is short tire life.

[GetShwifty]

Thanks for all the awesome advice!

"Good to hear on the NVH.

I'll probably stick with the same size rotors, simpler.

I knew race pads had higher heat tolerance but had no idea the heat capacity was part of it. Genuinely curious how they do that while maintaining other properties, but I'm a physicist, not an engineer or materials scientist, lol.

Hahaha, working hard on it. After hearing that my car needed brakes, diff mount bushing, battery, and has an oil leak in the pan, her bet on the total cost was $5k compared to the actual estimate of $4750! Gotta keep it clean

[dradernh]

Originally Posted by GetShwifty

I knew race pads had higher heat tolerance but had no idea the heat capacity was part of it. Genuinely curious how they do that while maintaining other properties, but I'm a physicist, not an engineer or materials scientist, lol.

As best I understand it, race pads hold more heat because they have more metal in them. Bimmwerworld can probably give you a fuller explanation.