[vasillalov]

Ok Folks,

I am planning to upgrade to LSD in the next month or so. This naturally means that the subframe is coming off. I would like to use this opportunity to replace and upgrade as many components as possible at this time.

So I am looking for your recommendations on what other components I should get.

1. Subframe bushings: I am planning on M3 bushings. I do not wish to be dealing with polyurethane as they generate too much NVH, they have the tendency to shear and the car will be mostly street driven. Any reasons why I shouldn't use M3 subframe bushings?

2. Differential bushings. This is where I need your help: There are a few different choices. What would you recommend and why? My car will never see a dragstrip so hard launches are too concerning to me.

3. Rear Anti-sway bar. Again, lots of options to be had. What would you recommend? I do not plan on lowering the car too much at all. Right now it is on stock Sport suspension, but eventually, I will get quality coilovers for better handling with the smallest drop possible. I do not wish to keep changing sway bars constantly.

Anything else that I might be missing?

Thanks for your time and help in advance.

Vasil

[Blaster400]

I'd do M3 subframe bushings and M3 rear sway bar when adding LSD. Other thing to consider is defiv lockdown kit to eliminate wheel hop.

[solishe]

+1. If diff lockdown kit overkill go with TMS Solid Delrin Race Diff Bushings

[CJ421]

M3 subframe bushings are a great upgrade (they are a full bushing unlike the stock ones). It's hard to argue with an OEM BMW M part. I have & enjoy them.

I'd skip upgrading the rear sway if you plan on upgrading the dampers and springs, as higher spring rates will provided plenty of stiffness back there. It's not a good idea to make the rear too stiff, as it needs flexibility for consistent power delivery. You might however consider doing the front M3 sway, that makes an appreciable difference.

Add adjustable rear toe arms to your list, which will cure the toe steer our cars suffer from under acceleration.

[MikeR1994]

I feel as if the M3 subframe bushings don't really make enough of an improvement to justify the cost. They are far better and if you can't stand feeling any vibration at all they're the way to go, but delrin and aluminum bushings would be my first choice. The aluminum subframe bushings from Turner are only something like $300. Have you ever actually ridden in a car with solid subframe bushings? I think you would be surprised by how little the increase in NVH is. In my honest opinion it's pretty minimal. I have a friend with them and there is more NVH in my car due to the coilovers I run and just my suspension setup in general than there is in his. When I pony up and order a Quaife I'll be getting the TMS aluminum bushings.

[MikeR1994]

However I would hate to have you make a decision that you might regret based off what I've said. If you want to compromise a little extra performance for a little extra comfort, the M3 bushings are for you. They're drastically better than what you have now. Don't go for full solid unless you're ok with sacrificing a little comfort for a little performance.

[abhishriv]

I would look into getting a differential lockdown kit. I noticed after getting my LSD installed that I get some wheel hop, which is pretty annoying. I believe the lockdown kit also Comes with the differential bushings. Look into it, think devif makes the kit. And install would be easiest while LSD is
Going into car anyway.

[jippii ensio]

Originally Posted by CJ421

M3 subframe bushings are a great upgrade (they are a full bushing unlike the stock ones). It's hard to argue with an OEM BMW M part. I have & enjoy them.

I'd skip upgrading the rear sway if you plan on upgrading the dampers and springs, as higher spring rates will provided plenty of stiffness back there. It's not a good idea to make the rear too stiff, as it needs flexibility for consistent power delivery. You might however consider doing the front M3 sway, that makes an appreciable difference.

Add adjustable rear toe arms to your list, which will cure the toe steer our cars suffer from under acceleration.

+1
M3 subframe bushings for sure. Possibly toe arms. The rest only if you personally have felt the need for them.

[Mavus]

Originally Posted by CJ421

M3 subframe bushings are a great upgrade (they are a full bushing unlike the stock ones). It's hard to argue with an OEM BMW M part. I have & enjoy them.

I'd skip upgrading the rear sway if you plan on upgrading the dampers and springs, as higher spring rates will provided plenty of stiffness back there. It's not a good idea to make the rear too stiff, as it needs flexibility for consistent power delivery. You might however consider doing the front M3 sway, that makes an appreciable difference.

Add adjustable rear toe arms to your list, which will cure the toe steer our cars suffer from under acceleration.

^ This

don't upgrade rear sway until you select/define suspension parts. you may not need it at all.

[GreekboyD]

Originally Posted by solishe

+1. If diff lockdown kit overkill go with TMS Solid Delrin Race Diff Bushings

I bought these last month.

Solid bushings on a street car?

[vasillalov]

Good points everyone! I appreciate the input. I think I will hold off on the RSB for the time being.

As for the solid delrin bushings, I don't think I'll live with the reduced comfort year round. The car will never see a drag strip or hard launches so the potential wheel hop is not of concern to me.

Now, for the more technical question:

Which fastener components should I replace and which can be reused during the LSD install. I want to pre-purchase everything in advance so that my shop won't have to waste time and at the same time I won't have to be worried about reusing older fasteners.

Thanks in advance.

[CALWATERBOY]

Originally Posted by vasillalov

1. Subframe bushings: Any reasons why I shouldn't use M3 subframe bushings?

2. Differential bushings.

3. Rear Anti-sway bar.

[1] Nope!

[2] Don't bother for street use.

[3] Do NOT install without a Limited Slip Differential!


Perhaps the very best first mod is a LSD, Quaife or Wavetrac. With that, the base is laid for everything else....

[cvc 22349a]

Originally Posted by CJ421

M3 subframe bushings are a great upgrade (they are a full bushing unlike the stock ones). It's hard to argue with an OEM BMW M part. I have & enjoy them.

I'd skip upgrading the rear sway if you plan on upgrading the dampers and springs, as higher spring rates will provided plenty of stiffness back there. It's not a good idea to make the rear too stiff, as it needs flexibility for consistent power delivery. You might however consider doing the front M3 sway, that makes an appreciable difference.

Add adjustable rear toe arms to your list, which will cure the toe steer our cars suffer from under acceleration.

Yes but not the 'torque steer' due to the oe differential bushings which are too soft and give too much driveline flex for a modified 335i with lsd and grippier tires.

Vasil,
What rear spring rates are you going to run? That'd determine, for me, which rear subframe bushings to use (and rear anti roll bar; not M3 imo). I like my M3 subframe bushings for a DD with 500+ lb rear springs. No one mentions the BMW Group N subframe bushings; they're harder durometer rubber than M3 but not rigid like delrin, aluminum; they're twice as expensive though...You don't need to drop the rear subframe to install a lsd but if you do for the subframe bushings, I'd do firmer diff bushings at the same time. You'll experience rear torque steer (for lack of an appropriate term) with the added traction of a lsd and grip of whatever tires you replaced your rft's with.

[crypticc]

Originally Posted by CJ421

M3 subframe bushings are a great upgrade (they are a full bushing unlike the stock ones). It's hard to argue with an OEM BMW M part. I have & enjoy them.

I'd skip upgrading the rear sway if you plan on upgrading the dampers and springs, as higher spring rates will provided plenty of stiffness back there. It's not a good idea to make the rear too stiff, as it needs flexibility for consistent power delivery. You might however consider doing the front M3 sway, that makes an appreciable difference.

Add adjustable rear toe arms to your list, which will cure the toe steer our cars suffer from under acceleration.

Won't upgrading the front arb without doing the rear just induce large amounts of under steer?

[vasillalov]

Originally Posted by CALWATERBOY

[1] Nope!

[2] Don't bother for street use.

[3] Do NOT install without a Limited Slip Differential!


Perhaps the very best first mod is a LSD, Quaife or Wavetrac. With that, the base is laid for everything else....

...But I will be installing an LSD. That's the reason why I am taking all the trouble.

[CJ421]

Originally Posted by crypticc

Won't upgrading the front arb without doing the rear just induce large amounts of under steer?

It's the opposite effect with our cars actually. Increasing the stiffness of the front reduces understeer. The less roll in the front, the better.

Originally Posted by cvc 22349a

Yes but not the 'torque steer' due to the oe differential bushings which are too soft and give too much driveline flex for a modified 335i with lsd and grippier tires.

I can vouch for the torque steer; I have stock diff bushings, they are the only thing I haven't upgraded. Torque steer in my car isn't that noticeable since I am stock power-wise, but it was when I was catless w/ tune &c.

[tres]

OP since your car will be a street machine get the m3 subframe bushings, install your lsd and then go from there but its almost most guaranteed you will be making more suspension modifications after a few months of driving.


Anything else that I might be missing?
upgrade your brakes
either better pads/rotors or bbk

[vasillalov]

So basically diff bushings are a must. TurnerMotorsports offers two different kits:

http://www.turnermotorsport.com/p-19...e-e82-e9x.aspx

and

http://www.turnermotorsport.com/p-15...e-e82-e9x.aspx

The difference is in the two smaller bushings.

First with all delrin:



Second with solid bushings:


Which one would you recommend and why?

[vasillalov]

Originally Posted by tres

OP since your car will be a street machine get the m3 subframe bushings, install your lsd and then go from there but its almost most guaranteed you will be making more suspension modifications after a few months of driving.


Anything else that I might be missing?
upgrade your brakes
either better pads/rotors or bbk

Thanks for the feedback. Yes, while the car is mostly street driven, I do participate in my local BMWCCA chapter and for the past 2 years I've been going to track days. So the car does see about 10-15 road course events per season.

Yes, suspension will come later and it is inevitable. For now I want to tighten the driveline and get LSD.

Brakes are already done. Before I go fast, I need to be able to stop fast.



EDIT:

So question: If I am dropping the subframe to install M3 bushings, wouldn't it make sense to upgrade to M3 sway bar since the subframe is already coming off? I mean, I don't want to have to do this work again to install the RSB later.

[tres]

in my opinion the only way to tighten the driveline is to get the delrin bushings or the diff lockdown kit and some poly trans mounts which may generate some nvh.

I had the tms solid diff bushings and still got wheel hop in the rain i dont get it anymore since I got the diff lockdown kit.

Originally Posted by vasillalov

Thanks for the feedback. Yes, while the car is mostly street driven, I do participate in my local BMWCCA chapter and for the past 2 years I've been going to track days. So the car does see about 10-15 road course events per season.

Yes, suspension will come later and it is inevitable. For now I want to tighten the driveline and get LSD.

Brakes are already done. Before I go fast, I need to be able to stop fast.



EDIT:

So question: If I am dropping the subframe to install M3 bushings, wouldn't it make sense to upgrade to M3 sway bar since the subframe is already coming off? I mean, I don't want to have to do this work again to install the RSB later.

[tres]

both will do the job one will just require some attention. aluminum wears faster, delrin is self lubricating. Race teams also use different types of bushings to get the same effect while adhering to the race rules. You dont have any rules on the street and youre looking for trouble free driving. So i would go with the delrin I've had it on my car for almost 2 years and no issues I also drive my car year round.

Originally Posted by vasillalov

So basically diff bushings are a must. TurnerMotorsports offers two different kits:

http://www.turnermotorsport.com/p-19...e-e82-e9x.aspx

and

http://www.turnermotorsport.com/p-15...e-e82-e9x.aspx

The difference is in the two smaller bushings.

First with all delrin:



Second with solid bushings:


Which one would you recommend and why?