John V's STS GTUs build thread
 

Don't know if many are going to be interested in this but I'm building up a 1990 GTUs for the STS class of SCCA Solo. I have a full build sheet that details what will be done but needless to say I'm starting with the engine. The car has 175,000 miles on it and the engine runs okay (starts right up, idles okay), but it's pretty tired. The 6-ports are stuck closed, it burns a bit of oil and it just needs a rebuild. I bought the car for $950, and considering that it's in fine shape. It doesn't have a spot of rust on it, even the (original) exhaust!

The interior was trashed - the kid who owned it before me broke the driver's seat, installed stereo amps behind the seats, broke most of the vents, etc. Couple pictures of the interior - after fixing the outer door handles and removing all of the stereo wiring. Oh, and an aftermarket alarm that had to be ripped out. What a pain. I'll be installing a motorcycle battery in the driver's side storage bin and routing the cables to the engine bay, so I'm leaving it semi-disassembled for now. New seats (Corbeau A4's most likely, because they're cheap) and a new steering wheel will be going in. The shifter is worn out, so a short shifter will be going in.

These pictures were taken after about four hours of interior disassembly and a LOT (a lot) of cleaning. The car was filthy. And the owner was a smoker. Ugh. After a good shampooing, the carpets aren't bad. And the car is all there and all stock, which is nice.

http://i368.photobucket.com/albums/o...r/HPIM1631.jpg
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Started getting the engine torn out. The heavy front mounted battery goes away. The airbox is already out.

http://i368.photobucket.com/albums/o...r/HPIM1629.jpg

Have you ever seen bolts so clean? Everything was like this. I love California cars.

http://i368.photobucket.com/albums/o...r/HPIM1634.jpg

I took tons of pictures since it's been so many years since I've worked on an FC. The air conditioning (still R12, and still blows ice cold) will be going as well. Too heavy. The radiator needs a good cleaning but it was replaced not long ago - it'll be reused. I'll replace the foam rubber insulation.

http://i368.photobucket.com/albums/o...r/HPIM1635.jpg

Need some new oil cooler lines. Leaking at the crimps. I'll have a local hydraulic expert do it.

http://i368.photobucket.com/albums/o...r/HPIM1636.jpg

The car has a massive front cover oil leak. No big deal. The engine is going to be rebuilt.

http://i368.photobucket.com/albums/o...r/HPIM1637.jpg

Little bit of an oil leak? Yikes.

http://i368.photobucket.com/albums/o...r/HPIM1659.jpg

Getting there...

http://i368.photobucket.com/albums/o...r/HPIM1666.jpg

All of the intake manifolds are going to get hot tanked to clean out the years of grime cleaned out. Exhaust manifold is about ready to come out. This will be replaced by a custom header that mates to the first of the two cats on the car. The cats will be replaced by high flow units, but they have to be in the same location as the stock pieces. Good bit of weight to be saved here.

http://i368.photobucket.com/albums/o...r/HPIM1668.jpg

More to come. I only had two hours to work on the car today. Tomorrow I hope to yank the motor and then I'll start tearing it down. New rotor housings, a set of low mileage irons, and I hope to reuse the rotors and eccentric (possibly with new rotor / main bearings, if needed). Stock mazda parts will be used internally, per class rules.

Stay tuned :)

Why put cats if you are going to use it as a track car?
Looks grimy. Can't wait to see it cleaned :)

Yikes, that thing is pretty crusty :lol:. Sounds like you have a solid plan though, I look forward to more updates. :icon_tup:

For STS class in the SCCA you have to run cats

Class rules say the car needs the same number of cats and they need to be in the stock location. Such is life. Plus, I hate stinky cars.

Yeah, it's crusty. But it'll be cleaned thoroughly before reassembly. I'm kind of compulsive about cleanliness :lol:

A4s not Kirkeys? Otherwise looks like you are on the right track. I really hope this turns out to be fast.

Great to see you picked up a GTUs for so cheap. Can't wait to see the progress.

Someone actually bought a new plastic tank rad recently?
That's just weird.

STS rules state the seats have to weigh 25lbs minimum. I figure that's a good excuse to have a comfy seat that reclines so I can drive it on the street now and then. The A4 weighs about 23 lbs, and the sparco brackets are pretty light so it'll be close to the minimum weight.

The VIN on this car is crossed out as well and restamped to sell what was a '89 GTUs as a '90.

Looks like lots of cleaning needs to be done but it you’re off to a great start. (+1 for compulsive clean freaks!) Hope the engine internals turn out to be usable for you. I’m definitely interested in your build progress so keep posting the updates.
The VIN re-stamp is interesting. I’ve never seen that before. Learn something every day.
-Jeff

I'll have to hook up with you sometime and check out the car. I just got my trans back after having the miata gears put in, so I'll hopefully be putting it in next week. Very nice purchase though, I'm envious of those clean bolts! All mine are nasty.

What kind of engine & trans mounts are you going to use?

We'll see if it was a good purchase after I get to run it at an event. it needs a TON of work, and it's not exactly pretty. The trans mounts are nonexistent. Same with the motor mounts. The motor is tired. The suspension is tired. But I knew all that going into it and that's part of the fun for me.

Most / all of the mounts and bushings are coming from MMR.

Is this the car that came out of Boulder?

Yep.

Poly Mounts are rough. I have Mazda Comp engine mounts and had Banzai Poly trans mounts and it was rough. I've since switch the trans mounts to Mazda Comp. The Poly trans mounts did me in, you get a lot of vibration, I mean alot. It would all smooth out around 6500rpm and be silent, but up to that point, the whole car woould vibrate.

You are doing a purpose built car, but Just for comfort I suggest Hard rubber.

Stick to the mazdacomp engine mounts, I'm averaging 2-3 broken pass motor mounts a year right now with the puck style ones.

Thanks for the tips. I didn't know any hard rubber mounts existed other than the diff mount. Found the p/ns on mazdacomp's site.

Thanks!

John

Haven't bothered to download the pictures yet, but the motor is out. The A/C is all removed and sitting in a box (shame, because it worked great, blew cold and was charged with R12!) and the engine bay is ready to shine again.

This weekend, engine gets torn down and the engine bay gets cleaned. Not much will be reused from this tired motor - I have fresh housings, irons, e-shaft, rotors, and a seal/spring/gasket kit coming my way.

Spent the weekend cleaning engine parts for the most part. The irons I bought from a low-mile motor needed a little bit of work to be ready for a rebuild. You can see the shiny finish that comes from the housings being polished by the seals.

http://i368.photobucket.com/albums/o...oresanding.jpg
http://i368.photobucket.com/albums/o...oresanding.jpg
http://i368.photobucket.com/albums/o...oresanding.jpg

Following the advice of a rotary guru, I used a random orbital palm sander with 150 grit to eliminate the water marks and shine. Following that, using 500 grit silicon carbide wet/dry paper and kerosene (no joke) I did a wetsand on the housings using the random orbital. Then soaped up and powerwashed, dried, and sprayed with WD-40 to keep the rust away until the build.

http://i368.photobucket.com/albums/o...r/HPIM1670.jpg
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I did a thorough measurement of the housings with a dial gauge to measure grooving and a precision straightedge to measure warpage. Everything checks out.

Cleaned up the new rotor housings and the front cover. The rotor housings are off of another low-mile motor and look great.

http://i368.photobucket.com/albums/o...r/HPIM1675.jpg

The front cover took a lot of work and still has some dirty spots. I also found a small hole in the housing. This hole shows through to a bolt hole in the backside... but there's nothing to seal against here so I think it's OK. Still, front covers are cheap... I don't want to risk it. Frustrating because I had an hour plus into cleaning this one!

http://i368.photobucket.com/albums/o...r/HPIM1676.jpg
http://i368.photobucket.com/albums/o...r/HPIM1677.jpg

Picked up my engine stand and adapter and should be able to start tearing down the old motor and checking parts (I'll be selling what I can) and then off to build the new motor.

Yanked the transmission today. It needs new front and rear seals, and it was filthy. The front oil seal went out long ago and it covered the whole trans in an eighth of an inch of gunk which attracted all sorts of other crap. Took a good two hours of powerwashing and scrubbing to get it clean, and it's mostly clean.

http://i368.photobucket.com/albums/o...r/HPIM1693.jpg
http://i368.photobucket.com/albums/o...r/HPIM1694.jpg

I removed the clutch fork - looks good and it'll be getting a new throwout bearing. But not until the fresh seals go in.

https://farm3.static.flickr.com/2692...ffb2c83d0a.jpg

Got the old lump down to the basement and on the stand. Should get it torn down tomorrow.

http://i368.photobucket.com/albums/o...r/HPIM1688.jpg
http://i368.photobucket.com/albums/o...r/HPIM1688.jpg

And measured all of the freshened irons I prepped the other day. Need to measure the side seal tracing groove along the edge of the housing, near the combustion area.

http://i368.photobucket.com/albums/o...desealwear.jpg

The requirement is less than .004" of step wear. Realistically, less than .003" is desired. These housings are measuring less than .0015" so they're good to go.

http://i368.photobucket.com/albums/o...r/HPIM1690.jpg
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http://i368.photobucket.com/albums/o...r/HPIM1686.jpg
http://i368.photobucket.com/albums/o...r/HPIM1687.jpg

Need to check for warpage, but assuming they pass that, these are good to go in the new motor.

very thorough motor prep so far. i like it

Very awesome :icon_tup:. If more people bothered to go through these steps there'd be a hell of a lot less 'OMG rotaries are so unreliable' crap flying around.

Hey John, Just wanted to make sure you're getting all your OEM parts from Ray Crowe down here in Woodbridge. He's got the best prices around.
Looks awesome so far. I wish I had the patience to be that thorough.

On the transmission: Did you order up the new shifter bushings? Since you have it on the floor, now is always a good time to replace the shifter return spring and possibly the shift actuator. Because you know that plastic piece in the bottom of the actuator is going to break the second you reinstall the trans... LOL!

For those of us unfamiliar with STS rules: What plans do you have for the engine, or will it remain perfectly stock? Keeping the stock ECU?

Project looks great so far! -Jeff

ill need to try that myself :) i think you should finish it off with some valve grinding compound...