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PostPosted: January 9, 2017, 8:59 am 
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Thanks for the kind words guys. That course was really fast I actually got tunnel vision on the way back on one of the runs. It was a fairly simple course but was very different due to the higher than average speed. Looking a long way ahead and knowing exactly where you want to put the car in the important elements is crucial to driving the course fast.

There is no #1 for the champion, they just do class trophies. I know some other clubs to a year long Pax and Raw trophy's which would be cool but unfortunately they don't have that. They just have a cone killer award for most cones hit in a season, which I won on 2012 I think.

I have been temped to do a track day but safety is a concern for me. My tie rod broke across the finish line yesterday and it wasn't really an issue. If I was doing 130+mph at Sebring down the back straight that could have been much worse. SCCA does PDX days locally that are only around $90. When I did it in my Rx8 I had a great time but blew, my clutch and had engine overheating issues so it was an expensive repair. I also love the competition aspect of Autocross, most track days I can do are just lapping sessions so while fun no real competition.

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PostPosted: January 15, 2017, 9:07 pm 
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I have a few things going on with the car at the moment. Since obtaining the F20C I am completing as much as I can prior to doing the engine work which will allow me to run in DM, this gives me the ability to lighten the car by 330lbs.
Today I started working on the transmission. I have done some calculations and with my taller rear end, AP1 transmission and higher redline I have much taller gears.
Here is the new top speed in each gear after the engine and transmission changes.
1st - 57mph
2nd - 76mph
3rd - 114mph
4th - 145mph
5th - 171mph
6th - 203mph
I think the car would be aero restricted to 150mph (down hill with a strong tail wind). As such I have decided to remove 5th and 6th gears to save weight. I never use them and even if I go on the track or at the dyno a top speed of 145 is plenty, I thought about removing 3rd and 4th also but feel I lose too much practicality.
Attachment:
IMG_20170115_134500.jpg

At nearly 100lbs the transmission is not exactly light. Hopefully removing 5th and 6th will shave 15+lbs but really not sure what gears/synchros weigh. Being part of the drivetrain it's a great place to lose weight.
Attachment:
IMG_20170115_190839.jpg

I am rebuilding the Wilwood calipers as one brakes with so much more force then the other causing constant single wheel lock up or pulling the car to the side. I have ordered drilled solid (rather than vented) rotors saving about 6lbs of rotating, unsprung mass.
Attachment:
IMG_20170115_190900.jpg

Locally I am running in BM this year as both EMod and Dmod cars are legal in BMod so that makes me eligible for the year long trophy while switching classes mid year. Running BMod I'm well over minimum weight so I removed the 50lbs of ballast. Then for the National events and other local clubs I will run in the correct class and add weight for EM.


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PostPosted: January 15, 2017, 11:12 pm 
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So what rpm are you going to be running, 9k?

What ratio rear end are you running?

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PostPosted: January 16, 2017, 11:41 am 
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The stock F20C redline is 9,000 I plan to bump it to 9,400 and the rear end is 3.72.

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PostPosted: January 16, 2017, 10:37 pm 
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That's why I was off, I was thinking 9k not 9,400.

I have the 2.2 but I want the 3.7ish also and I wasn't getting quite the speeds you were calculating.

I'm used to the speeds of the stock 2.0 with stock rear end and since I'll be using the stock AP1 trans I figured the 3.7ish would get me a little faster than stock speeds which would let me get enough into 3rd gear to make it worth while on the autocross tracks near me.

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PostPosted: January 17, 2017, 9:41 pm 
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My diff is the 1989 1.5 way clutch LSD from the Supra and is a very nice diff. The Clutch ones are desirable for autocross and what the top guys tend to use. All manufactures stopped using them as they wear out and need servicing.

I upgraded mine with Weir Maxgrip kit http://www.weirperformance.com/maxgriplsdkits.html You can also tune the diff by adding shims to get the desired amount of lock. The diff weighs about 80lbs so on the heavy side but other then that I am really happy with it.

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PostPosted: January 20, 2017, 7:21 pm 
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The new drilled brake disks and rebuild kits arrived. The brake disks are 3lbs lighter each (bout 40% weight saving) which is a nice unsprung and rotating reduction. While rebuilding the calipers I discovered why one caliper seems to to brake with much more force than the other. It turns out I have an odd pair and one caliper had 1 3/8" pistons the other has much larger 1.75" (which was the one locking the tires all the time). As such I ordered a new caliper to match the smaller one. Hopefully that will sort my front brake issue out.
Attachment:
IMG_20170119_145305.jpg

The transmission rebuild is progressing, I have removed the gears added a spacer and started the rebuild, as well as ordered a couple of parts to replace a seal and a couple of pieces I damaged getting it open.
Attachment:
IMG_20170119_194743.jpg

The gears weighed in at 4.5lbs and the shift fork and extra lb for 5.5lbs total saving. Again some of the best possible weight saving as it is rotating and frictional mass early in the drive train.
Attachment:
IMG_20170119_194154.jpg

The job was rather fiddly and I definitely would not pay someone to do it but it was good experience.


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PostPosted: January 21, 2017, 4:22 am 
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The big caliper would have had about 60% more force on the pads than the other side - this should make a real difference for you. I'm thinking you have been missing a lot of braking on the front with one wheel not doing so much.

It's good to get weight out and rotational is a big deal, but I'm thinking the gears are mostly weight. Since they are small diamter they don't have a huge inertia. Here is a really good article that goes thru exactly this type of stuff. He made an Excel spreadsheet to study different clutch choices on a Formula Ford. If you're really good with Excel you can do acceleration graphs that even take into account the time shifting gears, that's amazing.

http://www.jameshakewill.com/clutch-size.pdf

Great find on the brakes, you're going to be happy once you get that sorted out. :cheers:

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PostPosted: January 21, 2017, 9:23 am 
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Location: 4AGE in S.E. Michigan
Paul
Where you able to dis-assemble the trans without any specialized tooling?
I was under the impression that it took $$$ tools.
Dave W


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PostPosted: January 21, 2017, 10:36 am 
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@Horizon job, the 60% increased braking sounds correct. The car would either lock the tire or pull the car dramatically to the side. It was strange because I checked the pads were the same and swapped the calipers side to side. They also appeared to both function correctly. I never even knew they had different piston side options. I have to say the wilwood stuff is great quality.

The gears are fairly small but early in the drive train. Coming before the rear diff, if all things are equal they would have 3.74 x the effective weight loss parts after the diff. They are also free spinning with the opposite shaft causing friction. I'm not sure how much of an improvement it will be but with the parts I bought it was less than $100. It's also cool to say it a modified 4 speed gearbox. That is a great article by the way I'll read it fully later.

@DaveW the only thing I needed to buy was the 14'' allen socket, unfortunately that still didn't remove the large nut with my 300lbs impact drill so I ended up hammer and chiseling it off. Other then then you need 10,12 & 14mm sockets and a good bearing puller to remove the gear and needle bearing off the final drive shaft. I broke the needle bearing by not getting completely under it. That was a $40 mistake. You also need something to separate the sirclip that holds the secondary shaft in place, I just struggled with needle nose pliers. I also replace the oil seal to the bell housing. I would recommend changing the synchros too which are about $100 each but mine look perfect so I left them.

Everything else it just time and a lot of head scratching about which part is next. There was a great DIY on S2K.com and a couple of videos on youtube. The main thing is remembering where and how everything goes, if you plan to do it take photos at every stage and label everything you remove. I wish I had more photos now I need to reassemble it.

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PostPosted: January 21, 2017, 12:24 pm 
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Some great info in the article, especially right at the end.
Attachment:
Screen Shot 2017-01-21 at 11.15.09 AM.png

This graph shows the total losses of engine power. Ultimately drag will completely stop acceleration.
I did notice that the gearbox in this example takes 20% of the power (which was a guestimate) hopefully by removing the gears going from 6 to 4 I should have made a nice reduction in loss. Maybe taking that 20% figure down to 19% or 18%. Who knows, hopefully it will make the car accelerate a little bit better and help get the times down.

For autocross where the car is constantly traveling at "slow" speeds in low gears. The drivetrain weight loss should have a relatively large increase in acceleration as it is all on the left side of the graph where drag is low.


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PostPosted: January 21, 2017, 1:23 pm 
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I thought it was a really good article too. I had forgotten how big a contribution the gearbox was making. I suspect he has overestimated it at least a bit. Just because it would get really hot, if it burned up 20 HP and 1 HP is about 750 watts that would be 15,000 watts total. That's more than the electrical service for my whole house provides.

I think you're doing a bunch of good stuff. The brakes are a big deal though, in my imagination it wold seem that would be a car length every time you brake for a corner on a road course and that would be about 1 second a lap. That's a lot for something you only spend a few seconds actually doing.

It will also demoralize your competition :twisted:

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PostPosted: January 23, 2017, 11:03 pm 
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I made a baffle pan today, it's something I have wanted for the engine for a while but would have had to take the engine out of the car or remove the riveted floor. I would prefer a dry sump system but that is just not in the budget at the moment. This was basically free as I had a scrap piece of aluminum laying around.
Attachment:
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Attachment:
IMG_20170123_213227.jpg


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PostPosted: January 29, 2017, 5:46 pm 
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I decided to reduce the mass of the clutch pressure plate this weekend. It took way too long for the weight reduction however I really enjoyed doing it. Playing with the drill press was better then sitting on my butt watching a movie. I dropped the weight from ~10lbs to ~8lbs so not a bad effort and certainly a good place to lose mass.

First I separated the pieces
Attachment:
IMG_20170128_121532.jpg

Lots of drilling and grinding
Attachment:
IMG_20170128_220446.jpg
Attachment:
IMG_20170128_220454.jpg

Final cheese grater looking product
Attachment:
IMG_20170129_144449.jpg


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PostPosted: January 30, 2017, 2:10 am 
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I've thought many times I'd like to lose some weight from my pressure plate as well, but never though of lightening the one I have. Are you able to balance it after the lightening?
Kristian

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