Review of Dinan 4.10 FD

[dcstep]

I picked up my '09 coupe after having the Dinan 4.10 FD installed, along with the Dinan throttle bodies and Active Autowerke Signature Exhaust, by Co's BMW in Loveland, CO. I added my comments about the AA to the long-active thread about the AA. I can't say much about the throttle bodies yet because I'm delaying dyno testing until I get a few miles on the FD.

There are no surprises about the 4.10 so far, with engine speeds running 6.5% faster than before. As already noted in another thread, the speedometer runs off a wheel speed, so the FD has no impact on the speedo, which runs about 8 to 9% optimistic in my car. I will probably autocross on 30-series 18" tires, to gain another 5+% of gearing.

There's 6.5% more torque delivered to the rear wheels and it's easy to feel, but also part of the other mods that I made at the same time. I'm VERY pleased to report that there's no detectable gear whine added. I hear a little bit of gear noise when coasting down, but it's very minor. At 76 mph, including the impact of the AA exhaust, cruising noise level only moves from 73 dB to 74dB and I can't really attribute any of that to the FD. (I use a Radio Shack SPL meter to get my readings and did the before and after on the same piece of road, to try to eliminate road noise from the equation).

The potential noise is was worrisome to me because I couldn't get a reliable report here, or anywhere else that I tried. The guys selling the other gears whispered that the Dinan was noisy and whiney, but that's not the case, IME. Thank goodness. Shame on the guys putting out the bad vibe about the Dinan gears.

Unfortunately, I need to run-in the gears for 1200 miles and do a fluid change at that time before I can do some dyno runs to document where I am. Right now I'm getting down to the bottom of a tank of 100 octane unleaded race gas, and with all the mods my butt dyno is telling me that I'm North of 30 hp gained, net. It might be more, but my butt has been wrong before, so I'll hold the line there for now. When the gears are ready I'll put in another tank of 100 or 105, run it in for a day or two and then go to the dyno for detail reports. (We only get 91 octane at the pump here in CO, so I'm electing to test in race trim).

All these mods together had no negative impact on the cruising enjoyment of the car and added substantially to the overall kick when you put your foot in it.

Dave

[camaross305]

Awesome ive been thinking about doing a 4.10

[doba_s]

not much said about TB ...

[dcstep]

Originally Posted by doba_s

not much said about TB ...

I was going to put that in another thread, but planned to wait on dyno readings. I'll say that the response is improved overall, but I can't tell by my butt how much is TB and how much is FD. Since FD will be all torque, the dyno will sort it out a little, when I do that in a few weeks, after the FD breaks in.

There is no driveability issue with the TBs, based on just a couple of hours so far. I can hear more intake sound up front, but only when I get in the throttle. My BMW mechanic says that everything fit real nice and there were no installation issues. Dinan puts every set on the flow bench before sending them out, so we're confident that they're up to spec. (Whatever that is since Dinan refuses to say anything other than "8% larger.")

So, I think they're a success, but the dyno will tell us more.

Dave

[sparkyg]

I spoke to Dinan and they said you don't need the 1200 mi run in. Just run it in for 500-600 mi and then get the rear diff oil changed

Give them a call and ask

[doba_s]

Originally Posted by sparkyg

I spoke to Dinan and they said you don't need the 1200 mi run in. Just run it in for 500-600 mi and then get the rear diff oil changed

Give them a call and ask

This is not true ... I don't know who you talked to , but Steve Dinan and Jeff(VP) both told me that i need to come back after 1200 miles to change diff oil ...


So, dcstep take it easy first 1200 and then take it back to service it ...

[dcstep]

My dealer is riding herd on me and going by the written instructions from Dinan. I may "cheat" a little, but only as much as the dealer will let me get away with. I'm going back soon for the Dinan springs, so if I'm approaching 1,000 miles then, I'll ask that the change the diff lubricant at that time and see what they say. (I'll do a few figure-8s every few days to make sure it gets some good usage).

Dave

[makots]

I got my 4.10 from Bavarian Performance Group/Diffs Online. And I am experiencing the same gains as dcstep! Its amazing. I love it and would recommend the mod to anyone who is willing to fork out the cash. Its very pricey to me but I'm very glad with the gains!

[signes]

Who did the install for you, I assume local? Looking forward to hearing more about it.

[dcstep]

Originally Posted by signes

Who did the install for you, I assume local? Looking forward to hearing more about it.

Co's BMW in Loveland, CO.

I live an hour away in Greenwood Village (below Denver) but got involved with Co's on the purchase because they would deal on an ordered '09 back in November when the local guys weren't offering as good a deal on an in-stock '08s.

I decided to give them a try, despite the distance, for this relatively significant work and I haven't been disappointed. They even offered to truck down a loaner and truck up my M3. I drove this time, but next time I may take them up on the offer. They have a covered auto-trailer, which I happened to pass on my way up there. They're really hustling for business. I like that.

Ask for Shelton Sanders to do your work. He's busy, busy, busy, so you'll need to schedule ahead. Besides being a great mechanic, Shelton is a car lover that understands the modding culture and our desire for extra fine work.

Dave

[signes]

Thanks. I live close to Cherry Creek but understand the need to drive a distance sometimes. Bought at Schomp and have service done at Gebhardt.

If we ever organize a group drive this Spring, it will be great to see the comparison of stock v Dinan.

[dcstep]

Originally Posted by signes

If we ever organize a group drive this Spring, it will be great to see the comparison of stock v Dinan.

I plan to do a few RMBMWCCA autocrosses this summer. Are you a member?

Dave

[signes]

Yes, will plan on doing those as well. Couldn't do it with my E46 M since it was a vert.

[dcstep]

Originally Posted by signes

Yes, will plan on doing those as well. Couldn't do it with my E46 M since it was a vert.

I'll see you there.

Dave

[dcstep]

BTW, I checked the speedo today. There's one of those radar speed signs near me, which gives an LED readout of your speed and blinks if you go more than a little over. When I go through at 30 mph indicated on the speedo the sign has always read 28 mph. Today, going through the same sign at 30 mph indicated it read 28 mph again. So, that dispells any worry about adding to speedo error by changing the FD.

Dave