brief dinan suspension track review

vasracer · 08-20-2009, 06:39 PM

It took me a week but,

I took my then stock 135i to cal speedway in may, and spent two days tooling around. Learned that the brakes fade a lot, and traction at both ends was limited on the stock rfts. I had a lot of understeer which I solved by braking a lot earlier, and then turning in. Trail braking mostly overloaded the front tires. Power oversteer was abundant. I had fun.

Last week, same tires, but stage 3 dinan suspension. Also much faster run groups, this time with speedventures along with cal corvette club. Crazy. At every corner, I had a zo6 on hoosiers basically in my trunk, with a couple of full racecars thrown in there for good measure. I ended up giving away a lot of apexes on purpose because I was clearly slowing a lot of people down. (2:03 at cal speedway roval, for reference...)

The car basically handled the same, I pushed the fronts way too hard, wore the sides down pretty good, and did a lot of scrubbing of the track with my front tires. My fastest times of the day where earlier when I was following a friend in a cayman S, and following his good line and braking earlier. On my own, later on, I was braking late, mostly because somebody faster was literally on my ass. What I didn't realize until late in the day was that my laptimes were slower because I wasn't able to get on the throttle early enough. I guess racers have to fight the urge to brake late when in traffic and just maintain their habits. I will say that the 135 is near impossible to spin, and I tried.

I will say that I did do some canyon drives with the dinan suspension, and on the street, the improvement in turn in and responsiveness is readily noticeable, compared with the stock suspension. The car takes to canyons with absolutely no drama, a moderate bit of inside rear wheel antics, but tons of grip. It was only at the track, where the suspension couldn't make up for my bad habits, where I was disappointed. (mostly with myself, though).

Did I say brief?

Maybe some real tires will help, I am guessing that the dinan suspension was not tuned with rfts in mind. I still recommend this for street driving, but I think that the tires are the real nemesis on the track.

Critical Mass · 08-20-2009, 07:49 PM

Thanks for the write up! I found it informative. Some really good feedback on what to expect with the upgraded suspension. I guess its time to get off those RFT's however.

Clap135 · 08-21-2009, 01:23 AM

What made you go with Dinan over say TCK or Cross? My cross suspension 9k/12k springs, under steer with 2.5 degrees of - camber is simply a thing of the past. I have to be careful how fast/hard i turn in now. The frist autox on the cross suspension, i made it to about the 3rd cone before my rear bumper smacked the exit gate. On the stock suspension i pretty much just plowed and spun the inside wheel.

Ruffan · 08-21-2009, 11:42 AM

Thanks for the write-up. Replacing the tires will help a ton by the way.

I've noticed that the Dinan suspension is significantly better on the track than stock, but it is without a doubt still a street setup. Once you get used to have more power than traction you can control the car very well, but you really have to be extra smooth in quick transitions, like esses, or the car will just scrub at the front end.

I've also found that the car takes a bit to long to settle when braking from a turn. At Summit Point I had a lot of trouble with turn 3. Coming out of the 180 degree turn 2 I was able to put down all of the power and make the turn a big sweeper where I only straightened the wheel for maybe 1 second prior to braking for turn 3. I was as fast as anyone on the track heading into 3, but I had some trouble getting the car perfectly settled prior to getting on the brakes. On the street the suspension is so much better than stock, but on the track it still is not quite tight enough to manage the full weight of the car at race speeds. At another point on the track under full braking the rear of the car would wiggle pretty consistently. It didn't really change my line, but it wasn't the most confidence inspiring thing. My front brakes were doing almost all of the work though, and the bias didn't feel as good as when I had stock pads on.

I've done a couple of track days with the stage 3 and I'm happy with how it's performing. I did leave my last 2-day event thinking about how I could tighten things up for the track, but realized that the car is still way better than I am, and it's almost perfect on the street, so I'm not changing anything as of now. I'll just have the pull the trigger on a 2010 GT3 RS for the track...

vasracer · 08-21-2009, 07:52 PM

Quote:

Originally Posted by Clap135

What made you go with Dinan over say TCK or Cross? My cross suspension 9k/12k springs, under steer with 2.5 degrees of - camber is simply a thing of the past. I have to be careful how fast/hard i turn in now. The frist autox on the cross suspension, i made it to about the 3rd cone before my rear bumper smacked the exit gate. On the stock suspension i pretty much just plowed and spun the inside wheel.

Wow, you're able to spin it?

My car is primarily for the street, so I didn't want something I would have to think about adjusting and balancing, etc. I had pss-9's on an e46 330i and I basically succeeded in turning that car into a jiggly mess that my wife wouldn't ride in....I simply don't have the time or skill to be a suspension engineer.

I think that I had expected more on the track though, because there has been quite an improvement with street driving with the dinan stuff. I will be going with the dunlop direzza's soon enough, and maybe a track day soon. Although my elise is looking lonely this summer...

Clap135 · 08-22-2009, 11:10 AM

I never stopped backwards yet, but ive gone full lock through gates during the first event on the suspension. It made me look like a rookie because I was so used to plowing the car. Like other have said, camber camber camber makes all the difference. Does the dinan suspension come with front camber plates?

vasracer · 08-22-2009, 11:13 AM

its interesting to note that in the recent motor trend article about 10 best performing cars, the comments about the 135i echo what we have been saying here....basically great until 7-8/10ths and then falls off. I think that's what i have been most disappointed in the 135i at the track. The dinan work made the car great on the street, but unfortunately, a track setup it isn't.

I wonder if most of the issues are tire related, and should I have upgraded that from the beginning and then did the suspension later if needed.

08-20-2009, 06:39 PM	#1
vasracer Private 6 Rep 97 Posts Drives: 2009 BMW 135i 6spd Msport Join Date: Apr 2009 Location: Santa Monica, CA iTrader: (0)	brief dinan suspension track review It took me a week but, I took my then stock 135i to cal speedway in may, and spent two days tooling around. Learned that the brakes fade a lot, and traction at both ends was limited on the stock rfts. I had a lot of understeer which I solved by braking a lot earlier, and then turning in. Trail braking mostly overloaded the front tires. Power oversteer was abundant. I had fun. Last week, same tires, but stage 3 dinan suspension. Also much faster run groups, this time with speedventures along with cal corvette club. Crazy. At every corner, I had a zo6 on hoosiers basically in my trunk, with a couple of full racecars thrown in there for good measure. I ended up giving away a lot of apexes on purpose because I was clearly slowing a lot of people down. (2:03 at cal speedway roval, for reference...) The car basically handled the same, I pushed the fronts way too hard, wore the sides down pretty good, and did a lot of scrubbing of the track with my front tires. My fastest times of the day where earlier when I was following a friend in a cayman S, and following his good line and braking earlier. On my own, later on, I was braking late, mostly because somebody faster was literally on my ass. What I didn't realize until late in the day was that my laptimes were slower because I wasn't able to get on the throttle early enough. I guess racers have to fight the urge to brake late when in traffic and just maintain their habits. I will say that the 135 is near impossible to spin, and I tried. I will say that I did do some canyon drives with the dinan suspension, and on the street, the improvement in turn in and responsiveness is readily noticeable, compared with the stock suspension. The car takes to canyons with absolutely no drama, a moderate bit of inside rear wheel antics, but tons of grip. It was only at the track, where the suspension couldn't make up for my bad habits, where I was disappointed. (mostly with myself, though). Did I say brief? Maybe some real tires will help, I am guessing that the dinan suspension was not tuned with rfts in mind. I still recommend this for street driving, but I think that the tires are the real nemesis on the track.
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08-20-2009, 07:49 PM	#2
Critical Mass Enlisted Member 37 Rep 40 Posts Drives: 2012 Jerez Black M3 Join Date: Jun 2009 Location: Aurora, Colorado iTrader: (0) Garage List 2012 BMW M3 [0.00] 2012 BMW X5 50i [0.00]	Thanks for the write up! I found it informative. Some really good feedback on what to expect with the upgraded suspension. I guess its time to get off those RFT's however.
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08-21-2009, 01:23 AM	#3
Clap135 Brigadier General 102 Rep 3,460 Posts Drives: 2009 N54 Join Date: Jul 2009 Location: Sticky's Mom House iTrader: (1)	What made you go with Dinan over say TCK or Cross? My cross suspension 9k/12k springs, under steer with 2.5 degrees of - camber is simply a thing of the past. I have to be careful how fast/hard i turn in now. The frist autox on the cross suspension, i made it to about the 3rd cone before my rear bumper smacked the exit gate. On the stock suspension i pretty much just plowed and spun the inside wheel.
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08-21-2009, 11:42 AM	#4
Ruffan Member 30 Rep 392 Posts Drives: '09 135i Join Date: Sep 2008 Location: Gotham iTrader: (1) Garage List 2009 135i [0.00]	Thanks for the write-up. Replacing the tires will help a ton by the way. I've noticed that the Dinan suspension is significantly better on the track than stock, but it is without a doubt still a street setup. Once you get used to have more power than traction you can control the car very well, but you really have to be extra smooth in quick transitions, like esses, or the car will just scrub at the front end. I've also found that the car takes a bit to long to settle when braking from a turn. At Summit Point I had a lot of trouble with turn 3. Coming out of the 180 degree turn 2 I was able to put down all of the power and make the turn a big sweeper where I only straightened the wheel for maybe 1 second prior to braking for turn 3. I was as fast as anyone on the track heading into 3, but I had some trouble getting the car perfectly settled prior to getting on the brakes. On the street the suspension is so much better than stock, but on the track it still is not quite tight enough to manage the full weight of the car at race speeds. At another point on the track under full braking the rear of the car would wiggle pretty consistently. It didn't really change my line, but it wasn't the most confidence inspiring thing. My front brakes were doing almost all of the work though, and the bias didn't feel as good as when I had stock pads on. I've done a couple of track days with the stage 3 and I'm happy with how it's performing. I did leave my last 2-day event thinking about how I could tighten things up for the track, but realized that the car is still way better than I am, and it's almost perfect on the street, so I'm not changing anything as of now. I'll just have the pull the trigger on a 2010 GT3 RS for the track... __________________ 2009 135i Dinan Stuff
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08-22-2009, 11:10 AM	#6
Clap135 Brigadier General 102 Rep 3,460 Posts Drives: 2009 N54 Join Date: Jul 2009 Location: Sticky's Mom House iTrader: (1)	I never stopped backwards yet, but ive gone full lock through gates during the first event on the suspension. It made me look like a rookie because I was so used to plowing the car. Like other have said, camber camber camber makes all the difference. Does the dinan suspension come with front camber plates?
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08-22-2009, 11:13 AM	#7
vasracer Private 6 Rep 97 Posts Drives: 2009 BMW 135i 6spd Msport Join Date: Apr 2009 Location: Santa Monica, CA iTrader: (0)	its interesting to note that in the recent motor trend article about 10 best performing cars, the comments about the 135i echo what we have been saying here....basically great until 7-8/10ths and then falls off. I think that's what i have been most disappointed in the 135i at the track. The dinan work made the car great on the street, but unfortunately, a track setup it isn't. I wonder if most of the issues are tire related, and should I have upgraded that from the beginning and then did the suspension later if needed.
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