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Rotus Rebuild


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Hey folks. So, I picked up this 1988 Rotus (I believe #44) a few months ago and figured I would post up here to share what I'm doing and hopefully get some help along the way.

 

I got this car from the original owner. At some point in the early 2000s, a turbo rotary motor was swapped in. The car was fast, but never ran quite right. So, at some point over a decade ago, the car was given to a shop where it was torn apart. And then it sat...for a long time. While it was in the shop, it caught on fire. Allegedly, a battery charger was sitting on the passenger fender and something happened that caused it to ignite. Thankfully, a passerby saw the flash, broke into the shop and put the fire out before it spread. There is damage to the passenger side panel, but the nose and hood were off, so they were fine.

 

Here is what the car as I picked it up from the shop where it had been for over a decade.

 

http://www.usa7s.net/vb/attachment.php?attachmentid=15999&stc=1

 

I got all the parts, including a new fender and the rotary motor, in pieces. Had to mount the nose to see what it would look like. Not bad.

 

http://www.usa7s.net/vb/attachment.php?attachmentid=16000&stc=1

 

I like the brown interior, though there are like 5 different kinds of gauges in the dash - something I'll have to change or I won't be able to sleep at night.

 

http://www.usa7s.net/vb/attachment.php?attachmentid=16001&stc=1

 

Here's the fancy wiring job that was done at the shop. I cut all this out and will be rewiring the whole car.

 

http://www.usa7s.net/vb/attachment.php?attachmentid=16002&stc=1

IMG_20190417_134231099_HDR.jpg

RotusNose.jpg

IMG_20190419_130325231.jpg

IMG_20190419_125705825.jpg

IMG_20191003_182215701.jpg

IMG_20191003_182242531.jpg

IMG_20191003_182256441.jpg

IMG_20191003_174622298.jpg

Edited by jloehlein
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With the car being 30 years old, sitting for at least a decade, some shady welding done to mount the rotary, and the fire, I've decided I'm going to pull pull the car down to the bare frame and rebuild the whole thing. It'll be getting a Miata drivetrain because I have a bunch of them and have no desire to mess with the rotary. Here is what the car looks like right now.

 

http://www.usa7s.net/vb/attachment.php?attachmentid=16005&stc=1http://www.usa7s.net/vb/attachment.php?attachmentid=16004&stc=1http://www.usa7s.net/vb/attachment.php?attachmentid=16006&stc=1

 

The body was made in 3 pieces (the two sides and the rear), but they were all welded together after being attached to the frame, so I had to get it off in one piece. After chiseling off at least 100 rivets and a little bit of bending, it's off.

 

http://www.usa7s.net/vb/attachment.php?attachmentid=16007&stc=1

 

If anyone has any good ideas about replacing that burnt section, let me know. My current thoughts are to just cut the sides off (either before the bend at the windshield or right before where the body gets taller for the rear wheels) and re-make both as separate pieces. That sounds pretty simple to me.

 

Anyways, at this point, I'm going to keep stripping the car down. I'm planning on getting the shocks rebuilt and replacing all of the bushings/joints. I found all the part numbers for the joints, bearings and brakes, but if anyone has any idea what control arm bushings were used, let me know!

 

I'm really bad at taking pictures while I'm working, but I'm going to try and do so and force myself to keep this thread updated.

Edited by jloehlein
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re-make both as separate pieces

 

Thats what I’d do.

 

It’s going to be interesting to follow the rebuild. Looking forward to seeing it come back to life, especially with the Miata drivetrain.

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I believe the bushings are Toyota. The Rotus manufacturer was a Toyota dealer. I have a Rotus chassis (also with a rotary) lengthened, with a glass over foam body that was patterned after the Lola Mk1. Will keep watching your work, and will dig out the mass of information that came with the car as a bit pertains to the chassis. john

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Got the frame all stripped down. Just need to separate the floorpan and it'll be completely disassembled. The only thing that gave me any trouble was that one of the serrated sleeves in a rear control arm bushing started wearing its way through the mounting tab. Had to pry the tabs apart to get it out. Contemplating just replacing the rear arms with heims and swage tubes - my Birkin is set up with all heims and it rides great. Thinking about what to do in the front, as well.

 

http://www.usa7s.net/vb/attachment.php?attachmentid=16025&stc=1

IMG_20191007_163149727.jpg

IMG_20191007_173104972.jpg

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While my car is a Stalker, these links may generate some ideas. The first link is of the original build of my car using a Chevette (remember those?) steering rack. The second link is from the rebuild with my switching to a Coleman Racing steering rack, complete with heims and tubes.

 

 

Original build

http://www471.pair.com/stalkerv/gallery2/main.php?g2_itemId=7594

 

 

Rebuild

http://www471.pair.com/stalkerv/gallery2/main.php?g2_itemId=30496

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Thanks, xcarguy! It's neat to see all the build pics - definitely a lot of ideas.

 

I've gotta wash the frame and then I can start cutting out the rotary mounts and fixing some random stuff. Once I fabricate the new mounts, I should be able to strip and re-paint the frame. Thinking about using ZRC Galvanizing Compound - a friend of mine sails and his anchor is painted with it. If it can stand up to tons of salt water exposure, it should be more than adequate for a frame/

 

Anyone have any recommendations on how to treat the insides of tubes to prevent corrosion?

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What condition are the motor and trans in? I have a turbo 13B Rotus here in northeast PA.

 

They're in the most exciting condition...unknown :smilielol5: I sent you an email through the forum, let me know if you don't get it.

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Good news - I got the donor Miata running this past weekend. It's got a VVT motor from an '02 in it and a Megasquirt. Now to take it all apart and figure out what parts of the harness I want to keep and what I want to re-make. Hopefully I can pull the drivetrain and get it mocked up in the chassis before Thanksgiving.

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You may want to rub shoulders with the Exocet folks down in Atlanta. Those guys are well versed at repurposing Miatas. Quite certain they can provide guidance on what is/isn’t needed on the harness.

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I used this on recommendation from others for the frame.

 

Rather messy as it drips out of any holes you have.

 

It uses a long flexible tube you insert into one end of the frame which then shoots the product 360 degrees inside the tube as you pull it out, once dry you have a protective coating on the inside of your frame.

 

http://www.usa7s.net/vb/attachment.php?attachmentid=16067&stc=1

Untitled - 1.jpg

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You may want to rub shoulders with the Exocet folks down in Atlanta. Those guys are well versed at repurposing Miatas. Quite certain they can provide guidance on what is/isn’t needed on the harness.

 

Good call - it looks like there are a few videos and threads online with Exocet owners paring down the harness.

 

I used this on recommendation from others for the frame.

 

Rather messy as it drips out of any holes you have.

 

It uses a long flexible tube you insert into one end of the frame which then shoots the product 360 degrees inside the tube as you pull it out, once dry you have a protective coating on the inside of your frame.

 

Thanks for the recommendation! Sounds pretty good to me and certainly can't hurt - I'll pick up a can.

 

Beware the VVT Miata engine is very tall, the VVT unit site on the top of the cam cover increasing the engine height by about 2 inches. I am not sure what Megasquirt you have but some cannot control the VVT unit so you might be able to just remove it.

 

Ya - I'm mildly concerned about the motor fitting, but after measuring it and measuring the car on the ground, I think I can maintain 4-5" of ground clearance. If it does create a problem, I may just swap it with the non-VVT motor in my Lemons car and mount it a bit higher. As for the Megasquirt, it's a plug and play kit for the Miata that has been running the car for the past 4 or 5 years. Thankfully, I'm friends with the guy who did the VVT swap in the car, so I've got all the details on it.

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  • 1 month later...

Well, it's been a busy past month with a couple track days (including a friend wrecking a car during the first, then us fixing it for the second) and an autocross. I haven't made a ton of progress, but I did manage to get the drivetrain out of the Miata and did a test fit in the Rotus. It seems like I'd only have ~3.5" of ground clearance with the VVT actuator touching the hood. I will try to find some FWD oil pans to see if that would gain me some more clearance.

 

IMG_20191114_120203790.jpg

 

IMG_20191121_152133813.jpg

 

One thing I am having trouble finding is info on the shocks. They're Koni 80-2091, 15.5" extended length, 11" compressed. Even the Koni rebuilders can't find info about them in their systems. Rebuilding cost seems pretty high. The spring rates are ~80lbs/in front and ~100lbs/in rear. I'd be interested in what other folks are using for shocks. I have no plans to race the car, just street drive and maybe autocross it non-competitively.

Edited by jloehlein
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[ATTACH=CONFIG]16210[/ATTACH]

 

[ATTACH=CONFIG]16211[/ATTACH]

 

One thing I am having trouble finding is info on the shocks. They're Koni 80-2091, 15.5" extended length, 11" compressed. Even the Koni rebuilders can't find info about them in their systems. Rebuilding cost seems pretty high. The spring rates are ~80lbs/in front and ~100lbs/in rear. I'd be interested in what other folks are using for shocks. I have no plans to race the car, just street drive and maybe autocross it non-competitively.

 

I am in the same boat that you are on the shocks. My Rotus framed Lola? has Carrillos and rides like a buckboard. And here in Arizona even the interstates favor off road suspension. The bushings were beat out of them when I got it. Btw the rotary was well suited to a 7. Worst thing is the "bark" but a turbo calms that down.

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