1975 Mazda REPU - Build and Repair thread

[The PC Doctor]

Amazing. Nothing like the scream of an old Rotary. Great to see someone do a simple version of a magnificent classic.

 

[chuyler1]

More wheel research.

My new endeavor would be to find a set of vintage "Appliance" wheels. I think they may have been the optional upgrade from the dealer back in the 70's.

Here's a set on a Datsun...

I can't track down any originals online. There might be reproductions but it will be tough to find in 6-lug.

Backup plan would be something like this (probably silver or white instead of black)...

http://www.minilitewheels.us/

I've got an email in to the company to see if they will make 6-lug rims for me.

 

[chuyler1]

After a few weeks of driving around with the stock AM radio I decided it was time to upgrade. I researched vintage radios on eBay and other sites but finally settled on a new RetroSound Model One from Crutchfield. It is a shaft-style AM/FM radio that also has a separate external USB/AUX input panel that can be mounted anywhere.

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A few notes about the RetroSound Model 1. There are numerous options for the knobs and faceplate. Make sure you pick the ones that will look good in your vehicle. At the time of this writing, my knobs hadnt arrived yet. I chose a black face plate with black center knobs and chrome outer knobs. I ordered the radio from Crutchfield and the sales person said they would ship separately as soon as they were in stock. The inner knob from the OEM radio will work on the new radio but the outer knob is the wrong size.Also, keep in mind that the USB input is for memory cards or USB thumb drives only. You cannot connect your iPod to it. You CAN however connect your iPod to the 1/8″ AUX input jack located on the face of the radio or the separate input panel.



Plan to spend a good deal of time installing this radio. The left and right knobs can be adjusted for many different positions which means it could take a little trial and error to get the shaft lengths and positions just right. For the REPU install, I had to bend the L brackets to get the radio narrow enough for reinstallation into the dash. The volume and tuning knobs are reversed on the REPU and RetroSound left just enough wire for me to hook them up in reverse.



While I had the center dash panel out, I took the opportunity to install new lights for the heater controls as well as a new light for the parking brake warning. JC Whitney sold generic replacement sockets that came with 3 different wattage bulbs. I went with the mid-wattage bulb and it was plenty bright.



With everything back in place, the new radio looks updated but still tasteful! I didnt have to cut anything to get it to fit. I need to get some silver paint to touch up the trim panel. Shown here without the knobs yet. They should arrive in the mail this week.



Im very impressed with the new lights. This photo doesnt do them justice, but it sure beats the pitch black dashboard I had on my first drive in the truck. Im even thrilled that the font on the RetroSound radio buttons is very close to the font on the heater controls!



As far as sound goes, I wont comment just yet. It is hooked up to a single 4″ Metra speaker in the dash. There is an option to switch FM playback to Mono. I will run it using this setup until I have the time to install proper speakers in the kickpanels.

The controls are pretty easy to use, but I was surprised that the outer knobs dont actually control anything. On the OEM radio, you could adjust the tone with the outer knob. I used it quite a bit when switching between AM stations. I was expecting similar functionality from those controls on the new radio but RetroSound has opted to use a menu system instead. You can navigate through the menu by pressing the buttons on the face plate. It has typical Bass and Treble settings as well as an EQ that provides some preset sound curves. Another nice feature is the ability to set the initial volume when it first turns on. Anyone who has left their radio on full blast and had a rude awakening the next morning will appreciate that!​

 

[chuyler1]

This morning I used a socket and a hammer to remove the locking lug nuts on the wheels and then I rotated the tires so the tread was facing the right direction. I hope it helps a little with highway stability.

While they were off I wrote down the markings on the back. Turns out they are a rare option for the 2000 GMC Yukon.

I know pretty much any GM truck rim will be a direct replacement...the problem is none of them look much better than these.

 

[newtontakedown]

the truck looks nice, i actually have a 74 repu. it isnt anywhere close to as origional as yours is but its my baby. im glad you did the radio conversion, i was wondering what i was going to do in my truck.
http://www.norotors.com/index.php?action=dlattach;topic=11714.0;attach=15907;image

do you know where to get the factory side mirrors?

 

[chuyler1]

I think your best bet for factory mirrors would be a junk yard...or start posting WTB threads at www.mazdarepu.com.



Exhaust Work today...

The previous owner did a great job with the exhaust with one exception: it was way too loud for driving around town. At first I thought it was an exhaust leak. Lui and Raul at Wankel Works installed a new gasket between the header and silencer but it was still to loud to cruise around town in 3rd or 4th gear. I guess running a straight pass-through style 2.5″ exhaust on a rotary engine just isn’t a “street” solution.

The previous owner’s exhaust consisted of a Racing Beat Street Port Header, Racing Beat 2.5″ pre-silencer, and Racing Beat 2.5″ Universal muffler. You can see the silencer and muffler before the axle in the photo above. The tip exited under the truck bed just past the axle which just made things worse. A typical Racing Beat street-port full exhaust kit contains their power-pulse muffler which has more silencing features compared to the universal stright-through muffler. As a result, the exhaust on my truck was painfully loud under any amount of throttle below 3,000 rpm. With a 4-speed transmission, it was hard to keep the engine at an RPM that wasn’t going to burst my ear drums.

Rather than mess with the system too much, I had a custom muffler shop install one additional chamber-style performance muffler after the rear axle. They cut the pipe right before the axle and installed a new pipe since the original pipe was rubbing against the axle. It took all of 30 minutes to finish the job. I highly recommend Lou’s Custom Exhaust in Manchester, NH!Driving home was a dream. The exhaust note was toned down in the low RPMs but still loud enough to put a smile on my face when I revved up to 7,000 RPM!​

 

[chuyler1]

New Clutch master and slave cylinders. Finally the clutch isn't auto-engaging when I'm trying to creep into the garage! That was a bit scary.

http://www.huyler.net/repu/?p=135

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[chuyler1]

New coils courtesy of Lui at Wankel Works. Haven't taken the truck out since I installed them to see if they make much difference.

 

[papsmagu]

sweet build and great looking truck. go with an S4 alternator and your can get rid of all the wires associated with the external regulator. also, cant tell from the picture but if you upgrade your dizzy you can also get rid of those UGLY reistors on your pretty blaster coils. i recently did this to my truck and also removed the glass fuse box and fusible links. its not a fun job but its certainly rewarding. i used an FD Engine fuse box for constacnt 12V and a FC Engine fuse box for switched power. Remember the stock glass fuse box has both constant 12V and switched. I have also seen people use the painless fuse boxes but i had the FC and FD fuse boxes laying around so i used them.

Awesome truck! keep us updated.

simon

 

[chuyler1]

I finally got the Rotary Power decal for the tailgate. There are a few bubbles I need to work out but it looks great!

 

[Reitrof]

Looks great Chris.

 

[chuyler1]

Got some projects brewing for this truck so I think i'll revitalize this thread.

Phase 1 (hopefully complete this winter)

* Quad throttle body EFI intake
* Adaptronic ECU
* AEM Smart Coils
* Electric crank sensor
* Electric fan
* Wideband
* Upgrading chassis wiring harness
* Upgrading fuse box
* RX7 alternator
* Side mount alternator kit
* Glimer pulley kit
* RX8 fuel injectors
* Upgrading entire fuel delivery system

Phase 2 (hopefully within the next year)

* RX8 6 speed transmission
* Lightweight flywheel
* Large Street Port
* LSD
* sticky shoes and lighter wheels
* suspension changes
* Bucket seats
* Stereo upgrade (but keeping it stealth)

 

[chuyler1]

I got a base-line dyno a few weeks ago so we know where we currently stand. The numbers are reasonable due to the upgraded exhaust...but there's plenty of room for improvement without opening up the block.

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[magnumP5]

Got some projects brewing for this truck so I think i'll revitalize this thread.

Phase 1 (hopefully complete this winter)

* Quad throttle body EFI intake
* Adaptronic ECU
* AEM Smart Coils
* Electric crank sensor
* Electric fan
* Wideband
* Upgrading chassis wiring harness
* Upgrading fuse box
* RX7 alternator
* Side mount alternator kit
* Glimer pulley kit
* RX8 fuel injectors
* Upgrading entire fuel delivery system

Phase 2 (hopefully within the next year)

* RX8 6 speed transmission
* Lightweight flywheel
* Large Street Port
* LSD
* sticky shoes and lighter wheels
* suspension changes
* Bucket seats
* Stereo upgrade (but keeping it stealth)

By "electric crank sensor" do you mean going to one of the later crank angle sensors or something like the trigger kits offered by Full Function Engineering? If the latter, bear in mind I'm not sure if any of their kits currently work with any of the Gilmer pulley kits. Also, if going with an off-the-shelf EFI throttle body it might be difficult finding something to work directly with the RX8 injectors. Why not go with something like Injector Dynamics injectors? What's the goal of the RX8 transmission? The overall ratio is pretty similar to RX7 transmissions, but there's just an extra gear stuffed in there. If you're looking for a lower cruising engine speed or something I'd recommend a later RX7 transmission over an RX8 do to cost alone.

 

[chuyler1]

The crank sensor will replace the distributer so there's no conflict with the glimer kit.

Not sure about injectors, they were a suggestion from Lui from Wankelworks but I'm open to suggestions.

The goal of the RX8 transmission is 1) it's the right length and won't require moving the shifter, and 2) it's newer. This truck is 40 yrs old, putting a 20 yr old TII transmission as others suggest doesn't make sense to me. I'd like the newest equipment so 20 years from now it won't be as hard to find parts. We're still not 100% sure the rx8 transmission will fit but we're gonna try. Backup plan is a SA22 5 speed, since I know for a fact it is a drop in replacement with no modifications. Doesn't resolve item 2 above but at least it gives me a taller gear.

Also, nothing about this build is really about saving a dollar here and here. Someone will eventually point out that I should just drop in an entire TII drivetrain because it's cheaper. I'm doing it for the fun. And ripping through a modern 6 speed is more fun.




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[Reitrof]

Go Chris!!

 

[bazooka joe]

Ditto!


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[chuyler1]

Did some test fitting to see what Miata seats will feel like. I need a bracket that will lift them up about 3". After placing them on some scrap wood the seating position was quite comfortable. Removing the lumbar padding gave me more leg room but I would have to put some of it back in so I don't have a thumper up against my spine. I don't plan to use these seat covers. I will order new ones from Katskin.

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[chuyler1]

And before you ask...yes, I plan to hook up the thumpers and seat speakers. I have a JBL MS-8 in my CX9 right now and I will probably pick up another for the truck. 8 channels, crossover, time alignment, and eq in a small package that will fit behind the seat.


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[Natey]

You oughtta turn this into a Build, Repair and Sell To Natey thread