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Re: Subtracting Weight from the Autocrosser
Posted by: Mike Stillwell ()
Date: March 23, 2017 07:37AM

Thanks for the info, Jonathan. If you have had good experience with it, I'll call it a win. What class are you running?

Mike
YS-117

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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: March 25, 2017 12:33PM

Dave -

Nate is right. They were made to spec by Eric Aos down in Portland. If I remember right we worked a trade for some things that he wanted. I know of a few others up here in the Northwest who have gotten them from Eric. Mine are a little different that some of the others. I requested a different length from the cross shaft to the ball joint than the stock dimensions.

The longer ball joint is essential (in my view) to obtaining the negative camber gain that I was looking for. Without it, the suspension will not gain much negative camber on compression or positive camber gain on extension. Both are necessary to keep the tires flat on the road surface during body roll in corners.

Mike -

I run in Street Modified in SCCA, an extremely competitive class.

At the Bremerton Sports Car Club, I will have to move up from the Medium Sedan class to the Prepared Sedan class because of the extensive internal modifications of the new engine.

At the Western Washington Sports Car Council events I run in a class called Open Street, which has rules very similar to SCCA's Street Modified.

The new engine will still be easily legal in Street Modified and in Open Street. In fact, the eventual supercharged version will still be legal there.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: March 26, 2017 08:19PM

The new street rubber arrived the other day from Tire Rack. The new RS-4 Hankooks were on back-order for a while, but I guess production is now catching up to demand.

These are Chevy S10 truck wheels from the 90s that have been bead blasted and then painted. Fronts are 15 x 7; rear have been widened to 15 x 8. You can see the weld in the picture of the wheel on the bench. I've been cleaning the back side and the inside of the wheels. I got the fronts all mounted up the other day. The rears are just about ready to go.

Front rubber is 225/45VR-15; rear is 245/40VR-15. Treadwear rating is 200.

Again, what I'm talking about above are the street tires and wheels. The racing rubber is Hoosier A7s. The fronts are 245/40VR-15s on a 9.25" Keiser 3-piece rims. The rears are 275/35VR-15s on 10.375" Keiser 3-piece rims.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: March 26, 2017 08:22PM

Oops... I guess they are "Z" rated tires, not "V".

Here are the pictures of the rear wheel and tire.


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Posted by: MattNall ()
Date: March 26, 2017 08:23PM

Great Street rubber... looks like they'll actually work well in rain?





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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: March 26, 2017 08:32PM

Matt -

Yes! I forgot to mention. They are not just the street rubber for occasional driving and getting back and forth to the autocross events (slicks and jack go where the back seat once was). They are also the rain tires for the autocross events. The old BFG Euro T/As just couldn't cut it any more.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Posted by: LawrenceNZ ()
Date: March 27, 2017 09:37AM

Hi there can you tell me what year chevelle ball joint you used or QA-1 part number or Afco

Many thanks
LawrenceNZ

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Re: Subtracting Weight from the Autocrosser
Posted by: chris ()
Date: March 28, 2017 07:32PM

Jonathan, any idea of the weight of the S10 wheels? I had looked at some before but didn't know if the backspace was okay.

'65 Monza 4 door
4 speed
110hp
Gardner, KS

Heart of America Corvair Owners Association

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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: March 29, 2017 09:33PM

LawrenceNZ -

I think the stock Corvair ball joints have a 7 degree taper. We couldn't find any long upper ball joints at the time that had a 7 degree taper so we went with the 10 degree taper ball joints and had to also buy a 10 reamer to change the ball joint upper seat.

I think the AFCO 20032-2LF is what we used. It is a low-friction type with a 1/2" extended stud. Keep in mind that my upper A-arms are custom make and we bought a upper A-arm bolt plate that matches the mounting bolt pattern of the new ball joint. It is a slightly different pattern than the stock Corvair one, even though they look similar. These AFCO ball joints will not work in stock Corvair upper A-arms.

Chris -

I don't know the weight of the S10 wheels off the top of my head. However, I still have one of the rears that does not have the tire mounted yet. So I could weigh it tomorrow and get back to you.

The backspacing on these S10 wheels is the fairly standard 3.75". The rears are widened 1" to the inside so the rears have a 4.75" back spacing. 4.75" works easily on the rear. 3.75" works on front. I've been happy with them for street wheels.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Posted by: Caraholic4life ()
Date: March 30, 2017 03:49PM

Jonathan Knapp Wrote:
-------------------------------------------------------
>
> Front rubber is 225/45VR-15; rear is 245/40VR-15.
> Treadwear rating is 200.
>
>

Wow, a 200 treadwear rating. That is higher than the treadwear rating for the factory stock tires on my 2000 Plymouth convertible.

It took a whole 50K miles of "Normal street driving" to wear out two sets of tires. I would imagine autocrossing would allow for maybe two seasons? smiling bouncing smiley

I am glad you were able to locate a light weight decklid without to much trouble. It looks great as it is.thumbs up

1965 Monza Coupe
Westminster, Maryland

MID ENG enthusiast &
prior Kelmark owner.



Edited 1 time(s). Last edit at 03/30/2017 03:51PM by Caraholic4life.

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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: March 30, 2017 10:14PM

Caraholic4life -

Treadwear ratings run from 100 to 500, 500 being the hardest and longest wearing, 100 being the softest. That said SCCA made 200 the minimum treadwear rating for cars in the Street Tire and various other autocross classes.

With that change, tire manufacturers are suddenly making ultra high performance street tires that have a 200 treadwear rating and that are not recommended for freezing temperatures. I imagine that I will be lucky if these tires last 10K miles.

But I'm pretty sure they will STICK! And that's the point.


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: March 30, 2017 10:33PM

If you really want tires that won't last, go with the autocross slicks shown below. Hoosier A7s: Treadwear rating is 40. I'll be lucky if they last a season.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Date: March 31, 2017 07:29AM

Those Hoosiers won't look that pretty after a run, that's for sure! They seem to work well, but they really turn to gum after the heat of the run.

Hope to see you at Kent's tomorrow.


Dan Davis ~ Pierce County, WA ~ CORSA Western Director + Corvairs NW + North Cascades Corvairs + Corvanatics
1966 Corsa Turbo coupe ~ ~ 1966 140 Corsa ~ ~ 1965 Monza 140/4 'Vert Sierra Tan/Fawn ~ 1964 Monza 'Vert (SOLD) ~ 1960 Monza Ermine White/Red PG ++ ~ 1965 Monza 140/4 Evening Orchid w/ ivory/black interior ~ 1962 Monza Wagon 102/4 ~ 1963 Rampside/Scamper ~ 1963 Red/Greenbrier ~ 1969 Ultra Van #468

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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: March 31, 2017 08:16PM

Chris -

I weighed the S10 wheels today: 17 lbs. for the fronts, 17.5 for the rears. That's less than the tires. The front tires are 21 lbs., the rears 23 lbs.

The Keiser Racing wheels are much lighter: 10 lbs. for the fronts, 11 lbs. for the rears. The Hoosier slicks come in at 18 lbs. for the fronts and at 20 lbs. for the rears.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Posted by: ROD ()
Date: March 31, 2017 08:49PM

Your Keiser wheels are sweet !

Rod Tetrault
El Cajon , CA
65 Corsa Yenko Clone / 65 Corsa EO Creampuff Vert
66 Corsa "JIMISH" Mid engine Turbo LS1 currently 2nd fastest Corvair in the USA
Class 5 Corvair powered Baja
61 Vintage Rampy
Corvair powered Buggy x 3
Enough hidden parts to build a space ship

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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: April 01, 2017 05:25PM

Adding it all up, the Keisers and Hoosiers "only" save me 38 lbs of rotating mass and flywheel effect. That's a little bit less than the 40-50 lbs. that I predicted. With that subtraction the car should weigh in at just about 2250 lbs. That's starting to sound good to me!

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: July 16, 2017 02:02AM

Finally getting back to some updates on the autocrosser. As a school teacher, summer is when I can get some stuff done.

The car was painted in 1991 and as you can imagine the paint has faded some over time. Reds fade more than some other colors, but I used Glazurit products which are very high quality. However, for a few years back in the early 2000s the car sat in a partially covered carport with just the nose sticking out in the sun. As you can see from the pictures, it faded quite a bit and picked up a lot of oxidation.

I got out the Meguiar's medium cutting compound and wool buffing wheel. After three rounds of cutting and a fine polish with Meguiar's swirl remover, it came out pretty good!

The first pic is what it looked like before I started. The second is when the driver's half is done. The third is when the whole is done. There's still work to do on the nose.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Date: July 16, 2017 04:56AM

Nice work, I love your wheel conversion.

In keeping with your thread theme, you did weigh the material removed from the hood and nose, right?smiling bouncing smiley I know you autocross and road race guys are serious about weight removal, but taking off paint??grinning smiley

All kidding aside, I love all the posts on your car, glad you are finding time for it this summer. Go run that thing!!

On another note, we put some of the new Conti's on a car with 750 HP in it and it's amazing how much grip they have on the street and in the wet.

---------------------------------------------------------------------------------------------
You're unique, just like everyone else...

Johnny B
Central WI

Wife's '68, 3.0L, twin-screw compressor and fuel injected in the works...

Project Pressurized Pancake


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Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: July 16, 2017 10:59AM

Johnny -

Had a couple of setbacks that slowed me down this spring. The block had to come back apart after checking the measurements on the cam. The profile needed some fine tuning.

I did get the new hollow front sway bar that I was looking for from Chuck Sadek. It is installed on the car now. It looks great with the Heim-joint ends instead of rubber bushings. I'll put up a picture soon when I get the car back up in the air and can take some pictures.

My 30-year-old Bilsteins seemed to have given up the ghost. The left front one will no longer compress all the way and locks up about an inch from the bottom of travel. They are out now and shipped back to Bilstein USA. Are they rebuildable? Will they honor the guarantee after 30 years? We'll see what they say.

I'm working now on building light-weight rear interior panels. I didn't want to use my current Corsa interior panels with the ash tray and an opening for the window crank that is no longer there. I'll post pictures of those when I'm done.

When will we see some pictures of the twin-screw pressurized pancake?

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Subtracting Weight from the Autocrosser
Date: July 16, 2017 11:19AM

Cool progress on your auto-x-r. Lovin' all of it.

Funny you should ask about the Project Pressurized Pancake; there'll be a thread started here in the coming months. Finishing up a 3-year boat restomod, sitting in interior purgatory right now. Once that is rigged and running, I'll start documenting it, right here, for sure!

Crank is offset ground, cylinders are bored, pistons balanced, need to modify heads and get custom rods ordered. Will bullnose crank, balance, and send for nitriding immediately after boat is complete. Thanks for asking.

---------------------------------------------------------------------------------------------
You're unique, just like everyone else...

Johnny B
Central WI

Wife's '68, 3.0L, twin-screw compressor and fuel injected in the works...

Project Pressurized Pancake


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