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Guest Message by DevFuse

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79 Brat conversion: you may question my sanity

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8 replies to this topic

#1 raging squirrel

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Posted 30 April 2012 - 04:40 PM

I suppose I should put this here, we will see if I can figure out how to post the pics. I am taking my 1979 Brat and converting it to rear drive only with a Metro 1.0 3cyl. engine and Suzuki Samurai transmission. I love the mileage of the Metro, but prefer the style and utility of the Brat. After serious number crunching and research, the project is feasible. I will need to shed a few hundred pounds to have a power to weight ratio acceptable for the engine. Half of this will occur as a mere bi-product of the swap itself. Some of it will come from the removal of non-essential parts and parts that are not compatible with the new power plant. This includes the original jumpseat assembly, in case anyone needs that for a restoration. After that, further weight loss will come from a variety of hand built parts as time and fishing allow.
Some numbers: My current 95 Metro has a factory curb weight of 1880 lbs. The 79 Brat has an official weight of 2175. The Metro and Samurai transmissions share similar gear ratios. The Metro has a final drive ratio of 4.10:1, XFI versions (the ultimate fuel saver version) has a final drive of 3.52:1. The Brat, I believe, is about 3.70:1. The optional Limited slip is a 3.90:1. All in all, a pretty good match for my goals. My two big obstacles are weight reduction and fitting a speedometer drive since the trans has no provision. A simple drive from a motorcycle hub mounted to the back of one of the front hubs (remember, the half shafts will no longer be there) will likely be the solution since the magnetic rotor in the speedo unit doesn't care what is turning it and they really are all the same from my research. The front tire on a street bike has roughly the same diameter as the tires on the brat, so it should be accurate enough. I will be using the Metro speedo unit most likely, since I believe that the fuel injection ECU does get input from a VSS (vehicle speed sensor) in the speedo. I am awaiting my diagrams to confirm this. I am using the simpler harness and more fuel efficient management system from a 91 Metro. Depending on how this version works, the ECU and camshaft from the XFI version may get swapped in later for an increase in fuel efficiency. The XFI stuff will cost HP, but the torque rating is the same. A few enhancements to build a little more torque would get me a power to weight ratio at 2000 lbs. curb equal to my current car at 1880lbs. Three ft/lbs. is all it would take. Still no rocket, but a great little runabout for a man who commonly racks up 120-300 miles in a single day.
Anyway, time for photos.

Attached Files

Edited by raging squirrel, 30 April 2012 - 04:50 PM.

#2 BlindSight


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Posted 30 April 2012 - 09:42 PM

Let us know how it goes!

#3 Dirk


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Posted 01 May 2012 - 04:11 AM

Sanity? I think your off your pickle!

But I can't wait to see the result!

My Gen1 2wd sedan weighs in at 850k same as your metro so I think you are in with a good chance of getting the weight down on the brat.



#4 Loyale 2.7 Turbo

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Posted 03 May 2012 - 01:57 PM

Nice Conversion Idea... I'll Like to see Photos.

In my Country, people do some conversions like That, but Usually for Reliability and / or the Lack of Parts.

Once I Came across a "Bratsun" in a Mountain Village, here you can see Pics of it:


Good Luck!
Kind Regards.

#5 dover



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Posted 26 March 2013 - 03:24 AM

How has it been going so far?


I'm a Metro guy myself.  I was thinking of this, and you might be better suited getting a 4 cylinder G10B to pickup a little more power.  If you're pulling too much weight it could reduce the fuel economy as well as the life of the engine. 

#6 bonvo


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Posted 26 March 2013 - 02:13 PM

i dont understand why it completly null and voids the point of the vehicle and come on the subi comes with a 1.6 even my tired ea71  in a wagon got about 30 mpg so metro mpg is possible with the original drivetrain so why codswallop with it?

#7 Leeroy


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Posted 26 March 2013 - 11:21 PM

Hmmm... the OP has not been active on the forum since May 2012... Perhaps not really a Subaru nut (like the rest of us!)?

#8 bonvo


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Posted 27 March 2013 - 01:12 AM

kinda what im thinking 

#9 BlindSight


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Posted 28 March 2013 - 10:11 AM

Sadness, was really hoping to snag his jump seats.

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