Underdog's '06 GRP Sedan 5MT

Tehnation said:

 

What is that?

That's the front bushing of the shifter assembly.

I just hate the big clunky tensioner. I also don't trust myself tensioning belts and every time I try to get a tool to measure it I get looked at like I have 16 heads and a "I just use my thumb"

 

What is up with the belt? It has to do with the fluidampr install right?

 

 

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Yeah I went to the self-tensioning belt back in 2015 because the tensioner was rusty and the bearing needed replacing. Thought I was saving myself some hassle, but you have to cut the self-tensioning belt off, and I needed it off to swap the crank pulley. Since I drive the car so infrequently and was putting in new parts I decided to just go back to the tensioner style. I still had my previous A/C belt so it ended up being a wash new stretch belt vs. new tensioner.

I've been doing it by feel for a long time, though I do usually put a straight edge across it and measure when I'm dealing with a new engine configuration.

I've gone back and updated posts earlier in this thread with more info on my diff swaps. You can find them here:

AP Suretrac R160 Install

Torsen Front Diff & 5MT DCCD Install

Whats your opinion on modding a 5mt vs going 6mt? I can't recall if all the 6mts come with dccd. I think the legacy 6mt is the cheapest one, not sure if it has dccd. If I could get one of those for the price you got it for I would be game, but you said they are hard to find. How much did you spend upgrading all the lsd's? Any part numbers or links for the lsd mods? What exactly did you upgrade for the lsds? I'm just trying to crunch numbers to see which route I should take. Are the lsds on the 6mt better than the 5mt? Can your 5mt take more hp with these mods? Edited December 22, 2020 by Tehnation

Oh man the cold air scoop trim to allow for easy removal, brilliant! You just saved me another step getting the front splitter hooked up to the car at the track

i really like what i m seeing on here !!

who wouldn't gotta love car porn!

Tehnation said:

Whats your opinion on modding a 5mt vs going 6mt? I can't recall if all the 6mts come with dccd. I think the legacy 6mt is the cheapest one, not sure if it has dccd. If I could get one of those for the price you got it for I would be game, but you said they are hard to find. How much did you spend upgrading all the lsd's? Any part numbers or links for the lsd mods? What exactly did you upgrade for the lsds? I'm just trying to crunch numbers to see which route I should take. Are the lsds on the 6mt better than the 5mt? Can your 5mt take more hp with these mods?

The Spec.B 6MT is not DCCD but is able to take the 6MT DCCD section from an STI 6MT.

I had a hard time deciding between upgraded 5MT stuff or 6MT swap, but decided that I'd rather keep my 5MT gear ratios (can get to 60 in 2nd) and my original gearbox rather than inherit someone else's problems. My power goals were never lofty enough that a 6MT was strictly necessary, though 5MTs are a gamble at any power level. I'm currently at 350whp with probably another 50 still on the table (octane limited) and feel perfectly comfortable street driving my 5MT for a long time. I would not say the differentials increased the power handling capability of the transmission - they're all about traction. Edit: there was an element of right place, right time re: upgraded 5MT parts which definitely helped push me in this direction.

My front and rear diff are Torsen style (the Suretrac is not "Torsen" but operates on the same principle) so they are mechanical with no service beyond gear oil replacement (i.e. no clutches). The center diff is 36/65 torque split and will operate as an open diff unless you run a controller. I went with MAPDCCD because I wanted the ability to adjust the lock manually, as well as develop my own maps for it.

The front diff is RST-1903 from Rallispec. I think I paid ~$1500 back in the day for it (new). I installed it myself which required some special tools from Kent Moore/SPX (all listed in the Legacy FSM). You can find part numbers in the transmission chart pdf I attached, or the links I shared in my last post, above  

I swapped out my viscous rear diff for a Suretrac R160. It already had the correct ring and pinion, and was installed in a much newer R160 rear end. Again, more info in the links above.

Rallispec Transmission ID Chart.pdf

i think you have the diff setup i want !! spec b 6 MT is open diff in front so it no go for me

now you make me think keep the 5 speed !!

do you mean you can lock you center diff with the MAPDCCD? that what i m looking for .

Beautiful build.

There are far more ways to upgrade a 6MT so I most likely wouldn't advise someone to go to a 5MT unless there were other considerations (fitment, cost, weight, gearing, preference). Since I kept my original gearbox I didn’t have to worry about the condition of the gears/synchros.

Yes the MAPDCCD can be operated in manual, auto, or any of four user-programmed maps. In manual mode the dial controls lock % directly, and in auto it controls the aggression of the algorithm. I have the unit mounted in the glovebox and am planning to wire a remote display of the output to the clock area.

Attached screenshots of my four maps (1 street and 3 tarmac). They are set up very rudimentary and I mostly leave it in auto mode because I don't have the time or space to test my own maps beyond the limit of traction, nor an accessible knowledge base from others. When I operate it in manual mode it is mostly transparent because I have sticky tires and traction is never an issue.

Oh man the cold air scoop trim to allow for easy removal, brilliant! You just saved me another step getting the front splitter hooked up to the car at the track

 

You’re going to love it. That was such an annoyance every time I wanted to get the snorkel out of the way. 5 minutes with a dremel later...

No new content, just bumping the thread so it's easier to find.

I'm going through your thread and am taken by your technical ability and cleanliness. Hope I can see the car in-person at a meetup someday.

20 minutes ago, Enlight said:

I'm going through your thread and am taken by your technical ability and cleanliness. Hope I can see the car in-person at a meetup someday.

Wow thanks for the kind words - I really appreciate that. I’ve certainly learned a lot throughout my ownership of the car and even now there’s a long list of things I still want to do with it. It’s encouraging to see folks like yourself who continue to invest in these cars for the awesome vehicles that they are. 

Well I guess the car decided to give me one last kick in the head... or maybe it's a last ditch attempt to get me to fall back in love with it?

After replacing the battery I needed to run out to get some oil and a few other odds and ends. Fired up the car for the first time in a while and had erratic strings of misfires on cylinders 1 and 3. Seemed to be at idle only, and smoothed out at 2k+ rpm. Occasional individual misfires on cylinders 2 and 4. Eventually threw a CEL and misfire codes only. On initial starts it purrs like a kitten, it's only after 30 seconds or so it starts to act up.

- Swapped in a new spare coilpack - no change.

- Pull all four plugs and they look clean.

- Compression and leakdown shows 130PSI and 4-6% across the board.

- Boost leak test revealed tiny leak from EPDM cap on one of the unused ports on turbo inlet. Replaced and verified leak was resolved. No change in misfires.

- Swapped OCVs to see if problem followed to bank 2, no change.

- Oil and coolant look good.

- Engine ground straps are in great shape.

- Drained the couple months-old fuel and added 4 fresh gallons of 93 with seafoam. After some rough idling things seemed to smooth out a bit. Took the car out for a loop and the misfire gradually settled down to very infrequent individual misses at idle. Figured it was just sticky injectors from sitting for a while.

- Went to start it up two days later and erratic strings of misfires have returned, perhaps even more frequent than before.

I'm now wondering if my front O2 sensor is getting wonky. Still feel like the injectors (ID1000s) could need a proper cleaning, but it doesn't make sense to me that that specific problem would yield intermittent symptoms. I may start with the O2 sensor as it is likely easier than pulling the injectors, on account of the injector cover brackets used on the STI manifold. The BRZ/GR86 is looking better by the moment.

Dont forget the fuel pressure regulator, pump, etc.  I would check fuel pressure. 

7 hours ago, m sprank said:

Dont forget the fuel pressure regulator, pump, etc.  I would check fuel pressure. 

Thanks Mike. I have a gauge in the cabin and its 45-47PSI on cold start, then settles right in at 35PSI after the FPDC% comes down to 33%. It definitely still misses during that initial 100% FPDC period, but it seems worse at 33%. Also today only cylinder #1 is having the consistent miss, with cylinder #2 occasionally racking up low-mid single digits. #3 and 4 are quiet today.

I put in some chemtool B12 , as a diagnostic indicator rather than a solution. I also noticed that if I bring it up to 2500-3000 rpm and then let it come back down it idles nicely for a little bit before the misfires start again. Curious.

I'd love to get another set of ID1000s so I could try swapping in a new one for troubleshooting, but they've been replaced by the 1050x which will require tuning adjustments.

 

You could also buy some ID1000's used for cheap and send them out to have cleaned.

18 minutes ago, Enlight said:

You could also buy some ID1000's used for cheap and send them out to have cleaned.

Yeah I posted up a WTB on NASIOC earlier and got some hits already.

I have had a few odd ones like this before.  Check all the normals, I recommend an injector service.  I will say this, AVCS can malfunction and not throw a cel. 

Good point - ran into that way back when some debris got into my cam sprocket on a previous engine. I’ll do a quick observation of the AVCS angle before I pull the injectors later today. 

19 hours ago, Underdog said:

Yeah I posted up a WTB on NASIOC earlier and got some hits already.

@UnderdogI have a set of ID1000s, shoot me a DM. They are used, but should help you out with any troubleshooting you need to get done.