Stabilizing rear end on Dinan S3

Notdoneyet · 12-12-2016, 12:23 PM

New to the forum, big salute to all who contribute!!
So I picked up a (near) complete signature stage 3 Dinan 335i coupe. Car has the following Dinan mods:
Intercooler
Oil cooler
CAI
Stage 3 software
Sway bars f/r
Springs
koni yellows
Shock mounts
Diffsonlne three clutch 45/45 LSD
Forged Dinan 19" with 265/30 f and 275/30 r
25000 miles and MiNT

Problem is that the car was built with stock subframe bushings and stock RTABs

!

The additional rubber and torque are displacing the rear end and torque steers from the rear. Under load feels like my e36 used to with worn RTABS... Did a few searches and looks like the turner solid sf bushings do not add significant NVH and seem like a good remedy. Talked to Turner and they feel like I would not need RTABs since the mileage is so low and most of the rear end stability gains would be had by the sfb vs the RTABs if they are in good condition. Thought I would run it by the brain trust here and see what you think.
But since the trailing arms have to be dropped to drop the subframe to do the sf bushings it wouldn't be much of an additional cost. Whadda ya think?
Also was thinking locking the diff, although Turner didn't seem to think it was necessary. I currently have no issues with wheel hop. If recommended is the vwettish piece the preferred way to go?

Anyway, thanks for taking a look, happy to be part of this community!!

Notdoneyet · 12-12-2016, 12:30 PM

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whyzee125 · 12-12-2016, 06:22 PM

Car looks great! Just needs spacers. Most seem to do Subframe bushings of choice and sometimes solid diff bushings. I've never been in a 335 that had a squirrely rear end but those who have seem to have good results just from what I mentioned.

boro92 · 12-12-2016, 07:27 PM

Definitely do alloy or delrin rear subframe bushes. This is where the rear axle precision would come from. I would not rule out the stock toe links as the bushings are pretty squishy there. Check that area out as well. Fwiw the current m3, cla45 and other performance cars are now all coming with solidly mounted rear Subframes from factory. the stock bushes are very very soft (even the e9x m3 ones are soft).
That said, have you verified that the alignment is spot on?

Notdoneyet · 12-13-2016, 07:40 AM

Hey thanks Why and Boro! I am going with the Turner solid aluminum for the SF. Most search results say moderate to no increased NVH with the solid SF bushings, but significant increase for solid RTABs. Any suggestions for low NVH RTABs that will still help?
Thanks!!!!

Notdoneyet · 12-13-2016, 08:53 AM

Boro - good point on alignment! Seems ok but wanted to wait on bushing install before doing. As far as contributing to the feeling of rear end deflection, there are just too many driving dynamics indications that the stock SF bushings are being overwhelmed vs an alignment only issue...imo. But will do four wheel alignment after the bushing install.
Any recommendations on the current diff lock that is favored? Most of the searches Returned were pretty old...

Notdoneyet · 12-13-2016, 09:01 AM

And, just to get this out if the way...
I agree with the forum consensus on Dinan. Overpriced and underperforming. I, however, paid pennies on the dollar and the car in its current state of tune satisfies my objectives for performance....for now. I just want to put it out there that I am not a Dinan sycophant and am receptive to the notion that there are "better" alternatives. Based on my previous searches, I was just compelled to write that...

HP Autosport · 12-13-2016, 02:53 PM

M3 subframe bushings and guide rods will be suited more for a street car or even a track car.

mob17 · 12-13-2016, 05:45 PM

I got the diff lock plate from vwetish. Helped significantly on keeping the rear straight on acceleration.

Julian2485 · 12-13-2016, 09:18 PM

I have m3 rsb and it was night and day. I'm xi also

Notdoneyet · 12-14-2016, 11:38 AM

Awesome! Thanks all!! SF bushings on the way, will report after install. Gonna do them first and benchmark improvement, then the diff lock, then RTABs (if necessary)

feuer · 12-14-2016, 12:48 PM

Quote:

Originally Posted by Notdoneyet

then the diff lock

Either one works great:
http://www.n54tech.com/forums/showpo...&postcount=233
http://www.n54tech.com/forums/showpo...&postcount=230
I originally got the kit but switched to the plate.

HP Autosport · 12-14-2016, 01:28 PM

Quote:

Originally Posted by Julian2485

I have m3 rsb and it was night and day. I'm xi also

Best choice for street use.

Julian2485 · 12-14-2016, 01:32 PM

Quote:

Originally Posted by HP Autosport

Quote:

Originally Posted by Julian2485

I have m3 rsb and it was night and day. I'm xi also

Best choice for street use.

Including hp front adjustable swaybar links

Notdoneyet · 12-15-2016, 03:57 PM

EXACTLY WHAT I WAS LOOKING FOR THANK YOU!!

So, to hijack my own thread a little, I am curious about the interaction between E-Diff and an LSD. Part of what I am experiencing is a unacceptable level "torque steering" while traction shifts from one wheel to another (and sometimes back again) under load with wheel spin and DTC engaged (or DSC off). Also torque steering from the back under load W/O wheel spin. Hence my sensibilities about needing SF bushings. But is it possible that, since E-Diff cannot be disengaged, that braking the low traction wheel by E-Diff is contributing to the torque steer in instances with wheel spin?
What are all of the performance implications of how they interact? Does E-Diff become a liability with an LSD?

HP Autosport · 12-15-2016, 04:27 PM

Quote:

Originally Posted by Julian2485

Including hp front adjustable swaybar links

Those are good to go with stock or upgrade sway bars up front.

Rears are so short that adjustable versions aren't going to do a whole lot for you.

Julian2485 · 12-15-2016, 04:28 PM

Quote:

Originally Posted by HP Autosport

Quote:

Originally Posted by Julian2485

Including hp front adjustable swaybar links

Those are good to go with stock or upgrade sway bars up front.

Rears are so short that adjustable versions aren't going to do a whole lot for you.

I'm running stock xi bar upfront with m3 swaybar bushings and brackets. I was really going to get rear adjustable endlinks but I guess I don't have to

Notdoneyet · 12-15-2016, 05:10 PM

I have this http://www.dinancars.com/product/d12...135i-328i128i/

Julian2485 · 12-15-2016, 05:20 PM

Quote:

Originally Posted by Notdoneyet

I have this http://www.dinancars.com/product/d12...135i-328i128i/

I seen this but it's not for xi only I

Notdoneyet · 12-16-2016, 08:50 PM

HP you sell LSDs, how do e-diff and an LSD interact? Anyone?

HP Autosport · 12-19-2016, 03:20 PM

Quote:

Originally Posted by Notdoneyet

HP you sell LSDs, how do e-diff and an LSD interact? Anyone?

You will find the e-diff(if you can even call it that) much less intrusive. Mechanical LSD is the way to go. BWM e-diff is brake actuated, nothing at the diff itself.

HP Autosport · 12-19-2016, 03:21 PM

Quote:

Originally Posted by Notdoneyet

HP you sell LSDs, how do e-diff and an LSD interact? Anyone?

You will find the e-diff(if you can even call it that) much less intrusive. Mechanical LSD is the way to go. BWM e-diff is brake actuated, nothing at the diff itself. e-diff electronics will not know you have a LSD in place, it will only detec much less traction loss.

M cars have LSD and traction control and they work seamlessly together.

12-12-2016, 12:23 PM	#1
Notdoneyet New Member 4 Rep 20 Posts Drives: 2007 335i Dinan S3 Join Date: Dec 2016 Location: Nashua NH iTrader: (0)	Stabilizing rear end on Dinan S3 New to the forum, big salute to all who contribute!! So I picked up a (near) complete signature stage 3 Dinan 335i coupe. Car has the following Dinan mods: Intercooler Oil cooler CAI Stage 3 software Sway bars f/r Springs koni yellows Shock mounts Diffsonlne three clutch 45/45 LSD Forged Dinan 19" with 265/30 f and 275/30 r 25000 miles and MiNT Problem is that the car was built with stock subframe bushings and stock RTABs ! The additional rubber and torque are displacing the rear end and torque steers from the rear. Under load feels like my e36 used to with worn RTABS... Did a few searches and looks like the turner solid sf bushings do not add significant NVH and seem like a good remedy. Talked to Turner and they feel like I would not need RTABs since the mileage is so low and most of the rear end stability gains would be had by the sfb vs the RTABs if they are in good condition. Thought I would run it by the brain trust here and see what you think. But since the trailing arms have to be dropped to drop the subframe to do the sf bushings it wouldn't be much of an additional cost. Whadda ya think? Also was thinking locking the diff, although Turner didn't seem to think it was necessary. I currently have no issues with wheel hop. If recommended is the vwettish piece the preferred way to go? Anyway, thanks for taking a look, happy to be part of this community!!
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12-12-2016, 12:30 PM	#2
Notdoneyet New Member 4 Rep 20 Posts Drives: 2007 335i Dinan S3 Join Date: Dec 2016 Location: Nashua NH iTrader: (0)	Here is a pic
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12-12-2016, 06:22 PM	#3
whyzee125 Brigadier General 2099 Rep 4,161 Posts Drives: Dinan stage 2 335i Join Date: Jul 2014 Location: Chattanooga Tn iTrader: (0)	Car looks great! Just needs spacers. Most seem to do Subframe bushings of choice and sometimes solid diff bushings. I've never been in a 335 that had a squirrely rear end but those who have seem to have good results just from what I mentioned.
	Appreciate 0 Quote

12-12-2016, 07:27 PM	#4
boro92 Second Lieutenant 150 Rep 268 Posts Drives: audi s4 lol! Join Date: Jan 2016 Location: canada iTrader: (0)	Definitely do alloy or delrin rear subframe bushes. This is where the rear axle precision would come from. I would not rule out the stock toe links as the bushings are pretty squishy there. Check that area out as well. Fwiw the current m3, cla45 and other performance cars are now all coming with solidly mounted rear Subframes from factory. the stock bushes are very very soft (even the e9x m3 ones are soft). That said, have you verified that the alignment is spot on?
	Appreciate 0 Quote

12-13-2016, 07:40 AM	#5
Notdoneyet New Member 4 Rep 20 Posts Drives: 2007 335i Dinan S3 Join Date: Dec 2016 Location: Nashua NH iTrader: (0)	Hey thanks Why and Boro! I am going with the Turner solid aluminum for the SF. Most search results say moderate to no increased NVH with the solid SF bushings, but significant increase for solid RTABs. Any suggestions for low NVH RTABs that will still help? Thanks!!!!
	Appreciate 0 Quote

12-13-2016, 08:53 AM	#6
Notdoneyet New Member 4 Rep 20 Posts Drives: 2007 335i Dinan S3 Join Date: Dec 2016 Location: Nashua NH iTrader: (0)	Boro - good point on alignment! Seems ok but wanted to wait on bushing install before doing. As far as contributing to the feeling of rear end deflection, there are just too many driving dynamics indications that the stock SF bushings are being overwhelmed vs an alignment only issue...imo. But will do four wheel alignment after the bushing install. Any recommendations on the current diff lock that is favored? Most of the searches Returned were pretty old...
	Appreciate 0 Quote

12-13-2016, 09:01 AM	#7
Notdoneyet New Member 4 Rep 20 Posts Drives: 2007 335i Dinan S3 Join Date: Dec 2016 Location: Nashua NH iTrader: (0)	And, just to get this out if the way... I agree with the forum consensus on Dinan. Overpriced and underperforming. I, however, paid pennies on the dollar and the car in its current state of tune satisfies my objectives for performance....for now. I just want to put it out there that I am not a Dinan sycophant and am receptive to the notion that there are "better" alternatives. Based on my previous searches, I was just compelled to write that...
	Appreciate 0 Quote

12-13-2016, 02:53 PM	#8
HP Autosport Supreme Allied Commander 4246 Rep 56,332 Posts Drives: F80 M3 Join Date: Mar 2007 Location: Santa Barbara, AP, Brembo, GIAC, Koni, Ohlins, Performance Friction, www.hpautosport.com iTrader: (36)	M3 subframe bushings and guide rods will be suited more for a street car or even a track car.
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12-13-2016, 05:45 PM	#9
mob17 Major General 402 Rep 5,614 Posts Drives: E92 335D Join Date: Mar 2012 Location: East Midlands, UK iTrader: (5)	I got the diff lock plate from vwetish. Helped significantly on keeping the rear straight on acceleration.
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12-13-2016, 09:18 PM	#10
Julian2485 Major 113 Rep 1,340 Posts Drives: Black lci e90 335 xdrive Join Date: Sep 2013 Location: New york iTrader: (1)	I have m3 rsb and it was night and day. I'm xi also
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12-14-2016, 11:38 AM	#11
Notdoneyet New Member 4 Rep 20 Posts Drives: 2007 335i Dinan S3 Join Date: Dec 2016 Location: Nashua NH iTrader: (0)	Awesome! Thanks all!! SF bushings on the way, will report after install. Gonna do them first and benchmark improvement, then the diff lock, then RTABs (if necessary)
	Appreciate 0 Quote

12-15-2016, 03:57 PM	#15
Notdoneyet New Member 4 Rep 20 Posts Drives: 2007 335i Dinan S3 Join Date: Dec 2016 Location: Nashua NH iTrader: (0)	EXACTLY WHAT I WAS LOOKING FOR THANK YOU!! So, to hijack my own thread a little, I am curious about the interaction between E-Diff and an LSD. Part of what I am experiencing is a unacceptable level "torque steering" while traction shifts from one wheel to another (and sometimes back again) under load with wheel spin and DTC engaged (or DSC off). Also torque steering from the back under load W/O wheel spin. Hence my sensibilities about needing SF bushings. But is it possible that, since E-Diff cannot be disengaged, that braking the low traction wheel by E-Diff is contributing to the torque steer in instances with wheel spin? What are all of the performance implications of how they interact? Does E-Diff become a liability with an LSD? Last edited by Notdoneyet; 12-15-2016 at 04:03 PM..
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12-15-2016, 05:10 PM	#18
Notdoneyet New Member 4 Rep 20 Posts Drives: 2007 335i Dinan S3 Join Date: Dec 2016 Location: Nashua NH iTrader: (0)	I have this http://www.dinancars.com/product/d12...135i-328i128i/
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12-16-2016, 08:50 PM	#20
Notdoneyet New Member 4 Rep 20 Posts Drives: 2007 335i Dinan S3 Join Date: Dec 2016 Location: Nashua NH iTrader: (0)	HP you sell LSDs, how do e-diff and an LSD interact? Anyone?
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