The Buchka 242 Daily Driver

harribert said:

Watch out, they may make it happen.

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It'll spin to 12k, but only once.

Just thinking about what the engine would need to rev effectively to 12k is making my wallet shrivel. The redline is currently set to 7000. Not sure if Alex has tried winding it out yet, but with the current gearing and mostly-stock nature of the engine, I can't imagine it's very effective at that RPM.

The car will be a hell of a lot more fun once it gets a different rear gear. Something like a 3.73. It doesn't have enough torque to use the 3.31 very effectively.

OK fine, we'll settle for peak power at 8500 RPM.

As for the rear gear, I can imagine, 3.31 is a smidge too tall for a W58. 3.73 seems to be a good match with a stockish tire size.

First Volvo with pneumatic valves?

Sounds great! 3.73 should make it a lot of fun.

Sweet!!!

After driving this car the other night I have to say it makes much more sense now with some power. Looking forward to further dialing-in of engine and suspension tuning.

It's super smooth even after the rudimentary tuning session. It does need shorter gears with the current engine output, but might actually be very livable with the 3.31s if it was boosted.

I followed Alex home when we left our shop that night and noted that it has that raspy S50/S52 BMW exhaust note. Sounds much meaner than a wheezy old B23F.

Duder said:

After driving this car the other night I have to say it makes much more sense now with some power. Looking forward to further dialing-in of engine and suspension tuning.

It's super smooth even after the rudimentary tuning session. It does need shorter gears with the current engine output, but might actually be very livable with the 3.31s if it was boosted.

I followed Alex home when we left our shop that night and noted that it has that raspy S50/S52 BMW exhaust note. Sounds much meaner than a wheezy old B23F.

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331's will nevar spewl, 373's ftw, 354's max for a highway cruiser.

Redwood Chair said:

331's will nevar spewl, 373's ftw, 354's max for a highway cruiser.

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3.73 is fun, even in my stock 245.

The CBR display is a nice touch. Fits well, and who doesn't want a huge tach?

Holy **** awesome. It does sounds pretty good. Got any plans to dyno tune it? Curious to know how much power that thing can actually make.

Amazing build guys. Great work as always

Thanks dudes, really appreciate the kind words.

the poi said:

Holy **** awesome. It does sounds pretty good. Got any plans to dyno tune it? Curious to know how much power that thing can actually make.

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Gonna get it to a reliable state and do a bunch of street tuning on the ancillary items (idle, cold start, etc), then take it to a dyno shop to do the ignition timing proper. I've heard good things about Church Automotive Testing in Wilmington.

Redwood Chair said:

331's will nevar spewl, 373's ftw, 354's max for a highway cruiser.

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I've been on the lookout for a set of 3.73 gears. It would be a nice upgrade since the car kind of feels like a dog after 2nd gear

More updates:

Got the megasquirt resetting issue figured out. Turned out to be an intermittent connection on the DB37 internal to the box. I first tried potting the wires to the connector with epoxy but it only made the problem worse. I suspect I locked one or more pins into a "bad" position that wouldn't let the car start at all. Ended up getting rid of the db37 and just soldering the wires directly to the MS mainboard and I think that did the trick. Here's a photo of the failed potting exercise.



Had another mechanical issue with the car this past week. The front half of the driveshaft is axially under-constrained because of the additional slip yoke on the W58. This coupled with what I think is some kind of imbalance or precession at freeway speed resulted in the center support bearing yanking itself out of the rubber donut and then pushing the donut out the back of the bracket.



Ended up enlisting the help of Karl to go fix the car in the parking lot of my girlfriend's place. The rubber donut was a little worse for wear but didn't look catastrophic. We bolted the driveshaft back together and drove it around a bit. Since it felt fine at low speed we decided to take the car to Pelican Parts Coffee and Cars on saturday morning.



The car was popular with older white haired men and asian dudes. Not really sure what that means.

After about 40 miles of driving at low speed we finally got the car on the lift and the center support rubber was completely wrecked, looked about 2 minutes away from failing entirely.



I have ordered a new bearing, a beefier 740 center support donut, an adapter bracket from Jao, and some other odds and ends to constrain the driveshaft better. Should have it back together this coming weekend.

While waiting on driveshaft parts to show up I decided to start working on the brake upgrade. I have a set of 330x32 Alcon rotors that I picked up for cheap but the rotor hats were the wrong size. I bought some material and got to turning













Karl did all the drilling so thanks to him for that. Next up are caliper adapters which should be less arduous than turning 20lbs of aluminum into chips. Going to be using some brembo 4 piston things I picked up here on tbricks cheap a while back. Hopefully it all works.

Mocked up the brakes on the car tonight. It's a tight fit but it looks like everything is going to just clear. The calipers were made for 28mm thick rotors and the ones I'm using are 32mm so I'll just space the halves apart a little bit with some shims. Once that is done I can design the caliper adapters and bolt everything on.

I'm planning on keeping the stock rear calipers, just swapping the rear proportioning valves for ones off a 240 wagon. That should bring the brake balance back to a pretty reasonable place according to the numbers I ran.

Nice work. One small word of advice I have been given after doing a similar brake setup, make vent holes in the hat between the bolts.

Dang you guys are cool.

All hail the Buchka bros. Im speechless. Amazing work. Classy looking 242.

Can you all elaborate a bit on the CBR gauge cluster installation? How tricky is it to mesh the existing Volvo warning lights etc with the CBR all-in-one setup? Speedo signal, tach and so on?

Kestrel said:

Can you all elaborate a bit on the CBR gauge cluster installation? How tricky is it to mesh the existing Volvo warning lights etc with the CBR all-in-one setup? Speedo signal, tach and so on?

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Some of it is very simple, other parts are more complicated.

The warning lights, indicators, and backlight are all just piped out to the back connector, so making them work is just a case of connecting the correct wires in the car. I designed a circuit board that makes it plug-and-play:


We modified the thermostat housing to accept a CBR1000RR coolant temperature sensor. That is wired straight to the cluster to show coolant temp:


The speedo and tach are a bit more convoluted. The tach expects 2 pulses per engine revolution to show the correct RPM. The megasquirt can only output either 1.5 or 3 pulses per revolution with this engine. The speedometer shows 10KPH per 100Hz, which translates in to a ~70.4 tooth tone ring on the rear diff. Obviously neither of these things are even close to lining up.

I was hoping to hack the firmware on the cluster to re-calibrate it, but that proved to be beyond my patience. Instead we opted to put a frequency multiplier/divider in line with both signals. It's just a small circuit board with a microcontroller that lives inside the instrument cluster and correctly re-scales the input signals.

Karl Buchka said:

Instead we opted to put a frequency multiplier/divider in line with both signals. It's just a small circuit board with a microcontroller that lives inside the instrument cluster and correctly re-scales the input signals.

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Specs on the frequency multiplier? I need something like that for my Land Crusher. It shows 10% lower speed vs. actual because of the 35" tires. There's one called the "Yellow Box" sold as a speedo recalibrator but it's >$90 so I've avoided ordering one thus far. The Crusher has an electronic speedo/odo but I'm not sure where the VSS is on that beast. Edit: I believe it's on the transfer case.

http://www.yellr.com/ordering.htm

Slee Offroad sells a plug & play unit for $200

http://www.sleeoffroad.com/products/products_speedo.htm

But the highest is Mark's 4WD at $240.

http://www.marks4wd.com/speedo-interfaces/speedo-correction/mfk2800-80.html

Alex - sorry to derail your thread.

The new MS firmware can scale the tach output as needed (at least on my MS3x).