Project: modding sixth gen Corolla sedan on a budget

[christofoo]

I got 43 MPG on yesterday's fillup!

Looking through the last 5 years of my logs (since hypermiling), I found 3 years with comparable (time-of-year) fillups, with an average of 35.3 MPG and a high of 38 MPG. (For the two years I excluded, both Oct-Dec tanks were 41.6 MPG, the reason I excluded them was they started in Aug or earlier rather than Oct, so they included a lot of summer driving. I drove it less those years.)

My feeling is that the AAP diaphragm problem was the biggest factor. The exhaust smells a lot better this year. See http://ecomodder.com/forum/showthrea...dle-23542.html for more details. I'm pretty sure the aero mods and block heater are helping too.

The AAP fix and block heater install happened mid-tank, so 43 MPG includes half a tank under poor conditions, as well as at least 20 minutes of extra idling. It looks like I'm poised stay over 40 MPG the whole winter. Maybe more.

I'm excited.

I still have a rolling resistance problem that shows up when the car has sat in the cold for a while. (The problem is obvious when I roll out in the morning. My driveway is partially inclined, my car grinds to a stop midway. It's like a mini coast-down-hill test every day. Need to do some more troubleshooting, maybe inspect the caliper assembly real careful.) Man, if I could just fix that... then do some aero work on the tail end... maybe soften the front-wheel well too...

[christofoo]

I investigated high rolling resistance in the front wheels that I've mentioned before. I took the brake calipers off the wheel and found the resistance still high, the brakes were not contributing. (Anyways as I've said before I can't hear the brakes scraping.) Since the resistance feels symmetric in the front wheels, and I did this in neutral, I feel pretty sure it's coming from the transmission or clutch. Now, I know that a retaining ring from the passenger side axle is AWOL which combined with high transmission resistance makes me nervous, but I didn't find any detectable level of metal shavings in the transmission oil when I drained it (twice) this year.

Curiously, I notice a temperature correlation, this is a cold weather thing. This morning rolling out of my driveway after running my block heater for two hours, I noticed that the resistance was absent, it felt like summer.

Maybe I should pose this question on the mechanics board?

(EDIT: never-mind about the clutch; transmission in neutral rules that out, right?)

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I also sanded out the rust around the windshield, primed painted and sealed up the gap with outdoor caulk. I was going to post pictures, but decided that the electricians tape, while it looks just like the OEM weatherstrip at a distance, seemed too redneck to post online, even for this car. Redneck or no, I'm sure it'll last longer this way, and I feel better knowing the rust wasn't yet deep enough to be structural (and that it's now sealed properly against rain entering the cab ).

(I guess this is more of a eco-repair than a eco-mod. Any repair is a eco-repair, for that matter. I've got 2 tons of steel I'm trying to save from the crusher.)

[christofoo]

These mods have been on the car for a while, but I finally got them *fixed* and took pictures.

I used a heavy gauge steel sheet from Home Depot for the mirror delete replacement panel. There is foam weather stripping between the car and my panel. Black spray paint prevents rust.



I like steel because it can be bent just a little to conform to the car. Also:

I like to make these panels tamper-resistant. In my Civic I used carriage bolts, which I prefer (pictures of that later), but the holes in my Corolla are too small for any carriage bolts carried by Lowes or Home Depot, and I decided against drilling out the car or ordering the right bolts online. My second choice is a flat-head machine screw, which I can (partially) counter-sink in the panel.

That leaves an accessible screw head on the exterior, but the answer is a self-locking nut (nylon retainer type) and washer. Can it be removed from the outside? Probably, but with difficulty. Imagine turning the screw heads and watching those nuts spin freely. (Nothing I do is going to resist an angle grinder though.)



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For the wheel skirts, I did corrugated plastic on a steel strip. I'm afraid these are my ugliest mod so far. They might look better if I paint them white like the car, initially I thought the opposite. EDIT: or what about a black-to-white sunburst?



(This picture also makes me think I need to hurry and fix that rusted out hole under the door, and this car is begging for side skirts, although the doors curve down past the plane of the wheels, which makes things complicated.)

So you can see my skirt attachment method:



What I've got here: two cabinet latches at the bottom. Two angle brackets attached to the wheel well retain the top portion in one direction (used to be velcro but I tore off the hooks on the angle bracket later on). Three angle brackets attached to the back of the wheel skirt that retain the skirt against the wheel well in the other direction (I added a 90 degree fold to the angle brackets). The latches and brackets are pop-riveted in place. I used outdoor caulk over the rivets in the wheel well, hoping to prevent rust there.

Pros:

• It pops on and off in a few seconds. I mesh the angle brackets at the top and then snap the cabinet latches at the bottom and I'm done.

Cons:

• It was really hard to get the cabinet latches positioned correctly, and they aren't aligned very well, so snapping them in place requires a few extra seconds. If I did it again, I would use a 1/8"-1/4" thick piece of plastic (ABS or PETG maybe) screwed onto the wheel well and then attach the latch to that.
• Riveting the angle brackets to the Coroplast looks crummy. Not that I like the look of black-painted Coroplast much anyway...

Other thoughts, now that I've done this once:

• MetroMPG's second wheel skirt attachment method is probably better if Coroplast is used. Keep it simple, don't obsess with how long it takes to undo some screws to remove the skirt. http://ecomodder.com/forum/showthrea...html#post37089
• I like Weatherspotter's method with sheet metal the best overall. Weather Spotter Rear wheel skirts - EcoModder His method might be compatible with cabinet latches. I do like the way the cabinet latches work, they are just a little more difficult to install correctly. (I'd probably have the same problem if I were making cabinets though .)

[christofoo]

What's the best (efficient) manual gear oil for a Corolla (89)? I'm leaning towards Pennzoil Synchromesh after reading this thread: http://ecomodder.com/forum/showthrea...wners-128.html, especially the last post (on p2) by AndyH.

But synchromesh isn't rated for the Corolla? If I found the right manual, I should be using 75W90 GL4 or GL5. I don't know how the synchromesh is different, but it doesn't have a weight or GL4 rating. But it is for a manual transmission, so won't it protect my gears adequately? The only evidence I've been able to find of Corolla owners using synchromesh indicates they mix it with more conventional 75W90 gear oil.

Background: I think the generic 75W90 I (and others) put in the gearbox is too viscous. Evidence?

• I've had a 'high rolling resistance' when cold problem with this car for at least a year. It's a bit subtle, most drivers wouldn't notice, but the contours of my driveway make it really obvious to me when I glide out and I'm also very suspicious I can 'feel' it affecting my glides.
• Reading around, oil in the differential seems to be the most critical in viscosity for MPG, some reporting as much ~10% improvement in MPG as a function of oil selection (30% in drivetrain losses for Metro's EV, which is a smaller number than above, although temperature may be a factor). In either case that seems generally consistent with my feel for cold weather drag on my Corolla.
• I know the rolling resistance is in the tranny, jacked up and removed front brake calipers and tested all 4 wheels by hand. (Previously I thought I heard drum brake dragging and did a new spring kit back there, might have helped (and I don't hear dragging now) but it didn't cure.)
• The clutch got rebuilt by a local shop in Feb 2012, most likely they changed the tranny oil. My memory isn't sharp enough to say whether that was exactly when I noticed the resistance, but it's a prime candidate.
• Also about the same time, I think I started noticing the shifting was a bit sticky. It's not grinding, and it's not a big deal, but there's more resistance to getting in and out of some gears when the drivetrain is cold, especially in cold weather.

I've changed the tranny oil twice since Feb 2012, once because I didn't know the shop had most likely changed it and I thought it was due and I had noticed the resistance, and again because I replaced a drive shaft. In both cases it was before I knew that all gear oils are not equal and I grabbed the cheapest 75W90.

[serialk11r]

I checked with the place I went to for an oil change about MTFs, and they said they only carry Honda MTF. Apparently Honda MTF is the thinnest one on the market! I would try that, I don't think a stock economy motor is going to put too much stress on the transmission gears if you're not always dumping the clutch.

[christofoo]

Good news and bad news.

I've had Honda MTF in the transmission for almost two weeks and all my morning driveway coast-downs have shown a marked improvement.

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Unfortunately, I pronounced my air dam dead on Tuesday. Back to the stock bumper - which looks awful to me now, aesthetically as well as aerodynamically. The little bit of snow plowing the air dam did at the end of last week pushed it over the edge, I had multiple new fractures around the forward bracing and multiple fractures at the side anchors.

I think the key problem is that PMMA EDIT: PETG has no business working as an air dam. Maybe it was okay in the summer, but I noticed it is way more brittle in cold weather. Also, I learned that the ABS air dam that I was inspired by (AndrewJ) was destroyed by 2009 http://ecomodder.com/forum/showthrea...tml#post105163.

I do think that my general approach in the end was not bad, with stiff material on top and more pliable material below. Quick thoughts on what would make this work better:

1. Cut rigid material higher. 15 degree approach angle, or basically equal to the bottom of the bumper. Many cars can just use the bumper, it just depends on how backwards the slope of the bumper is aerodynamically.
2. More durable stiff material, probably aluminum or steel sheet, but I think ABS would be fine if a 15 degree approach is observed.
3. More comprehensive strip framing.
4. More durable pliable material. Lawn edging does not stand up to repeated ground scraping, and I doubt that coroplast is a ton better. Conveyor belting seems like the way to go.
5. The alternative to pliable material on bottom is a movable air dam. There's some verbiage in our state safety inspection that makes me think it would be an issue though.

[j12piprius]

Originally Posted by christofoo

Back to the stock bumper - which looks awful to me now, aesthetically as well as aerodynamically.

Quick thoughts on what would make this work better:

2. More durable stiff material, probably aluminum or steel sheet, but I think ABS would be fine if a 15 degree approach is observed.

4. More durable pliable material. Lawn edging does not stand up to repeated ground scraping, and I doubt that coroplast is a ton better. Conveyor belting seems like the way to go.

The black grill looks awesome. Have you considered to redo it with aluminum?

[christofoo]

Originally Posted by johnlvs2run

The black grill looks awesome. Have you considered to redo it with aluminum?

If I had time I would redo the grill and both skirts in Al (passenger side went MIA).

(Also the passenger mirror is back on, UT inspection requires the mirror if the rear window is tinted. Doh.)

(Also the block heater is mis-behaving. Not sure what's wrong, but it makes popping sounds, like it's shorting, but I ohmed it out, and I don't see how it could be. Maybe part of it is not covered in coolant and I'm hearing a "fluid explosion" for some reason. Beats me, but in any case I'm afraid to plug it in.)

Actually if I were to go back to modding on this one, the ongoing Crr issue would top the list. My best measurement to date puts it at Crr=0.014. Best guess is the rear brake drums need to be turned.

Sorry, I'm still debating myself on the subject, but I feel pretty divested in this car. It drives like "money in the bank," but my wife and kids just don't like it. So it needs to go away. Only question is what I'll replace it with - Corolla, Camry, Civic, or Prius - 1995-2008 are fair game.

It seems like a shame to let go of something with a drivetrain in such good condition, and at best $1k resale value. But one thing I've learned from the Civic modding is to be more picky about the car you start with in terms of meeting your needs. (The 97 Civic's back seat is going to feel pretty cramped 5 years from now.)

[ps2fixer]

Depends on what you need I guess...

Corollas are nice for pretty good mpg, but they are a "low end" car. The camry is quite a lot higher quality but mpg suffers pretty badly.

Personally... I say go with one of these, I have no experience with any of the other cars though.

1993-1997 Toyota Corolla (33-45mpg) (make sure it is NOT a 3 speed transmission, it has a overdrive button on the gear selector, or just get a stick)
1992-2002 Toyota Camry (27-37mpg)(these cars basically never rust out or break down. 96/97 was the body change year, the newer ones are not quite as good as the older ones in my opinion.)

MPG figures above are best/worst case I have seen personally between myself or my dad driving.