J.A. Ackley said:Hey, it was good seeing a GRM member out in the wild!
Good meeting you as well, some posts from Overmountain are over in the L2wd car thread here if you want to check them out.
J.A. Ackley said:Hey, it was good seeing a GRM member out in the wild!
Good meeting you as well, some posts from Overmountain are over in the L2wd car thread here if you want to check them out.
In reply to ¯\_(ツ)_/¯ :
Awesome. Got to check that out!
A brief detour into steering stuff- I have been slowly getting something together on this front although I'm unsure whether I'll use it. The initial thought was that quicker steering would be better, and since inexplicably nobody makes a quick rack for these yet (it's a non-power rack where are you on this, quaife?) and since shorter steering arms increase the forces on the tierods and stuff (which is scary) I purchased a 1.5:1 afco quickener cheap on ebay. The huge chunky quickener since the tiny aluminum ones scare me, it would need to go in the column after the factory EPS motor:
So, because the set screw type splined couplers are also scary, I found some Empi pinch bolt couplers for the quickener itself, and through a bit of guess and check, figured out that the newer Corolla has a steering column segment that could be chopped up to make adapters. Then through favors from friends, cut up and machined and welded the Corolla shaft and made a BRZ-AFCO-BRZ pair of couplers:
That makes this, when assembled:
You might be thinking "that's gonna take up too much space" but part of the concept for this car is to shove the human ballast as far rearward as reasonably possible, and with that in mind it actually looks like it'd work pretty well and still leave plenty of collapsible column below it:
Now, I still don't love this setup- every coupler, and the quickener itself, is another potential failure point. And the real kicker- I've noticed that as I get faster, I'm doing a lot less windmilling of the wheel and the steering ratio in the L2wd car seems more and more like it's just fine; I'm not sure I'm gonna use this thing at all! But it's nice to have the option, I suppose, and I can delay this choice pretty much up to the moment the steering column support gets welded to the dash bar.
Could you design a modular column support to have the option to switch back and forth for different rallies? Id suspect that some would favor much quicker steering than others.
In reply to Dusterbd13 :
Totally could, and if I were to do this I'd definitely make a "dummy" shaft to swap out for the quickener if needed- it's the potential for mid-rally failure that worries me, though, and this stuff all weighs something too. We just got back from the most turns-per-mile rally on the calendar and I didn't really feel the need for quicker steering, which is why I'm thinking about this right now. Those same roads last year, in the same car, were a big reason I was thinking I needed it in the first place.
the things that really made my rally car work as a rally car is
yeah shocks and a more powerful motor is great too but honestly those 3 items really transform the car into competitiveness
Pete. (l33t FS) said:Double. Check.
As you are probably aware by now, Subarus stuck the pilot bearing in the flywheel, not the crank. The input may not be reaching the pilot, depending on how the flywheel and the adaptor plate are machined.
OK, so. The standard 12x32x10mm pilot bearing didn't really engage much at all. I ordered a still very cheap 12x32x16mm bearing to try:
This works, but I'd love more engagement. I'm not a huge fan of it sticking out of the crank either, but then again, where's it gonna go?
This is better but still not ideal- something like a 12x32x22mm bearing would be really good. And hey, I found one... in Bulgaria, but it's claimed to be NSK so I'm hoping when it gets here in like a month it has a part number I can order directly from somewhere closer. It's apparently for an AC compressor on something where all the specs are cyrillic characters.
If this doesn't work out, I can always draw up a press-in adapter for the crank since there's room to work with, but if I can make the whole solution one weird bearing that's one less custom part.
Funny how "weird part" becomes a synonym for custom fabrication with time! I think you have plenty of engagement with the bearing above, Bulgaria is overkill. There may be a good story in how the Bulgarians have figured out the confidential part number though.
Pilot bearing fit check means I bolted the transmission to the engine:
Which means, with some careful cutting, the next thing can happen:
Drilled some spot welds which will reach below the cut line on the transmission mount and driveshaft support bearing- I don't think I'm going to continue using a 2 piece driveshaft, but retaining that piece of the tunnel will help brace an area which ties into the seat supports later, and make a nice way to keep a broken driveshaft from doing too much damage:
And now, we ruin the car, again:
The tunnel is going to move back about 8.25" and I intend to reuse as much of it as possible, since it does a great job holding the shifter and transmission and generally being a transmission tunnel, although I was surprised at how heavy it is once separated from the car. The cutout above the bellhousing area is intended to give enough space for the coolant business on the back of the heads, and also for things like swapping the starter out and removing bellhousing bolts.
Now it fits!
I plopped a seat in there to see if this location would work out relative to where I intend to sit- seems workable:
Then I did a very rough check of pinion angle vs transmission output (I have a fancier digital level on its' way to dial this in before I weld anything) and used that support I'd welded to the chassis earlier and some stuff I had laying around to set the angle:
And with a bit of hammering and prying (this will obviously need to be dialed in once I have the exact drivetrain angle I want) and a little material lopped off the back of the tunnel, I simply dropped it over top and bolted the shifter and transmission mount back up:
Looks pretty good for a first test fit:
Obviously all that space up front will need to be filled, and there will be lots of tweaking and trimming before I weld anything to anything. The plan is to basically just wall in the gap from the tunnel to the firewall, although the top end will be different and, as long as I can figure out a safe way to do it, include an access panel so I can get to some of the stuff on the back of the engine from inside the car, since access from the front or bottom will be pretty difficult. This location should allow transmission swaps without dropping the whole package out, though, since everything that would interfere is moving back accordingly.
Very exciting!
Great idea to move the whole tunnel.
Tubes or formed sheet connecting the firewall to tunnel with flat removable panels would be so convenient! Could use rivnuts or something like that.
In reply to maschinenbau :
I can see that turning into a filet device in a roll if the panels came loose.
It looks like the BR-Z uses a double layer floorpan like the GD did. That caught me out on Colin because the driveshaft carrier threaded into only the bottom layer.
In reply to maschinenbau :
I'm thinking one, semi convenient panel up top and a nice solid welded tunnel everywhere else, but we'll see how it looks as the dots get connected.
According to my fancy new magnetic digital level, the drivetrain angles are pretty freaking close for just plopping it back together:
So the transmission is angled down .5deg, and the pinion is angled up 1.15deg- honestly if I had just zapped it together already I could shim the front diff mounts down a bit and be in business. My plan is to trim and bend the tunnel/floor interface to achieve the best fit I can and see where things land, since every bit of material I remove should continue to drop the transmission angle lower and juuuuust a smidge of that seems to be exactly what's needed to get the angles all happy.
Beep
Decided to see what the "correct" transmission angle would be, so I stuck the level back on and used some of those handy shims rockauto sends in their boxes to set things:
After staring at it and thinking about it for a bit, I pushed it back up by .45deg (9 rockauto shims) and left it there:
My thought is that, rather than aiming for perfect, I should aim for the easier-to-correct end of the tolerance range so that I can tweak stuff with minimal fuss as long as it actually winds up near where I intend it to; if I'm off by a degree or so, it'll either be in range or shimmable.
In reply to ¯\_(ツ)_/¯ :
Consider which way it will fail and set it farthest away from critical angle in the opposite direction. What gives first on the jumps? Which load is least well resolved? Aim away.
In reply to TurnerX19 :
The differential on the L2wd car takes the most hits for sure- good thing it's thick iron. This direction of slight misalignment should be helpful for that or a mushed front subframe.
¯\_(ツ)_/¯ said:According to my fancy new magnetic digital level, the drivetrain angles are pretty freaking close for just plopping it back together:
So the transmission is angled down .5deg, and the pinion is angled up 1.15deg- honestly if I had just zapped it together already I could shim the front diff mounts down a bit and be in business. My plan is to trim and bend the tunnel/floor interface to achieve the best fit I can and see where things land, since every bit of material I remove should continue to drop the transmission angle lower and juuuuust a smidge of that seems to be exactly what's needed to get the angles all happy.
that should matter less with IRS but close enough the better obviously.
In reply to fidelity101 :
Does it? I thought u-joint angles at both ends of the driveshaft were supposed to be within .5deg as a general rule, but I am willing to learn otherwise.
In reply to ¯\_(ツ)_/¯ :
Your general rule is correct. remember that your continues run angle is more prone to harmonic issues than the variables in a live axle.
Also, a center bearing can help reduce driveshaft vibration issues. The longer the driveshaft the more prone it is to acting like a jump rope at high RPMs and whipping around. I think I remember you saying you were omitting a center bearing. In any case I'm sitting here with my popcorn watching in rapt attention. I love your posts and rally reports. Keep up the good work!
In reply to GladlyTheCrossEyedBear :
Yep, planning on a single piece- critical speed for a 3" steel driveshaft at this length will still be well past the top of 5th gear, so we should be ok. If I have issues I could return to a 2 piece design but it hopefully won't be necessary.
¯\_(ツ)_/¯ said:In reply to fidelity101 :
Does it? I thought u-joint angles at both ends of the driveshaft were supposed to be within .5deg as a general rule, but I am willing to learn otherwise.
Within .5 but also less than 2-3 degrees absolute angle. depending on how fast you are spinning it.
I shoot for zero degrees in the black RX-7 because that sucker is spinning hard and you can feel 1 degree even if the two joints are complementary. It's more an issue under cruise or coast and not heavy load.
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