Corvair DiagramCorvair Photo
Corvair Center
home forum corvairs calendar links Corvair Podcast
California Corvairs
Clarks Corvair
Clarks Corvair
“Performance
“CORSA"



Chevy Corvair License Plate
Chevy Corvair Chrome Wheel
Corvair Center Forum :  Corvair Center Phorum The fastest message board... ever.
Corvair Center 
Current Page: 4 of 5
Re: Subtracting Weight from the Autocrosser
Posted by: MattNall ()
Date: August 11, 2017 10:07AM

Success! you want the larger version though;







MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: August 12, 2017 12:00AM

Matt -

Yes, I do! Which one is the larger version though?

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: August 12, 2017 12:13AM

Lee -

Once I go to flared fenders and wider wheels and tires, I will be under the minimum weight in SCCA Street Modified class. There is no minimum weight for cars with 275 or narrower tires. There is a minimum weight for cars with wider than 275 tires. I will have to add some weight back in. But then I can put it where I want it: more toward the front and below the wheel centers.

For now, the project has been to subtract weight from the rear to enhance the front/rear distribution and to subtract weight from relatively high areas to reduce the center of gravity. Hence the work on the rear deck lid, the rear window and the quarter windows.


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: 1bad67 ()
Date: August 14, 2017 03:05PM

I searched, but couldn't find the answer. Where did you get that carbon fiber decklid?

Eric
Portland Oregon



Pics of my '65 Corvair
Pics of the Convertible

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: August 15, 2017 05:03PM

Hi Eric -

Sorry. The CF deck lid is a one-off made by a guy up here in Tacoma. I had some things he wanted, so we worked a trade.

Did davemotohead ever get a hold of you?


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: August 16, 2017 11:24PM

I'm back to working on the engine and I ran into a problem. I used a Federal-Mogul engine assembly lube when putting things together and that seemed great. It was viscous and sticky. Seemed like it would stay in place for quite a while while I worked on completing the engine.

To deal with another problem I had to take the rods back off the crank and, lo and behold, what do I see? Rust on crank journal and the big end of the rod by the bearing insert. Who ever heard of engine assembly lube rusting parts. Here is the picture of the rust on the big end of the rod where the assembly lube squeezed out of the bearing and dripped out onto the rod.



Here is the picture of the rust around the oil hole on the crankshaft rod journal.



Here is the picture of the culprit.



Anybody else ever have this experience? The rust came off of the rod easily with 600 grit emery cloth. If it did this around the rod journal oil holes, I'm sure it did it also around the main journal oil holes. I'm going to have to re-split the case and take the crankshaft to be re-polished.


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: davemotohead ()
Date: August 16, 2017 11:56PM

Did you clean the oil holes out in the crank good with a stiff wire bottle brush until no dirt came out? Hot soapy water and WD-40 gets the dirt out and blow it dry, I have used the federal mogul stuff for years with no problems, how long did it sit? Yes I have been in contact with Eric, just taking me a while to get the parts together, sandblasting the stuff takes a bit.





Email me at: Dave Motohead

Sign my guest book!
[motoheadmall.com]
-----------------------------------
Rust Free Lancaster Ca

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: August 17, 2017 12:12AM

Dave -

Yes, the assembled rods on the crank sat for a couple of months, but regular oil would never do that. The crank was thoroughly cleaned before assembly. This same rust from the assembly lube has showed up (although less so) on the camshaft lobes which has not been in the block nearly as long as the rods have been on the crank. The rust seems to show up where oxygen can get to the parts coated with the assembly lube, i.e. around the oil holes but not at all on the bearing surface of the journal itself. Also, it happened a lot faster on the camshaft lobes which are always exposed to air. On the cam lobes you can clearly see where the drop of lube did not cover the entire lobe, but just rusted the lobe where it did.

It is very clearly related to the assembly lube. I don't think I'll be using this product again.


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: 1bad67 ()
Date: August 17, 2017 11:13AM

It's like the assembly lube had absorbed water. Never seen anything like that before.

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Date: August 17, 2017 07:39PM

Jonathon:

Sorry to read of your rust issue, I've never seen an assembly lube or paste cause that.

Torco MPZ is used for assembly lube on high dollar turbo engines manufactured where I work. We've implemented it about 13 years ago and it's pretty amazing how well it protects, especially in high friction areas.

---------------------------------------------------------------------------------------------
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


Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: August 22, 2017 11:33PM

Problem: with the steering arms relocated to provide better Ackerman, bump steer has been accentuated. The more the suspension is compressed the more the front wheels toe out. This becomes a problem for two reasons. 1) The car is already toed out slightly for better turn in. 2) I load the trunk with quite a bit of stuff when heading out to the track, so the suspension is more compressed and the street tire scrub terribly on the inside edges while I am driving out to the track.

Now that I have expensive new street rubber I have decided to do some work on an idea I have had for quite a while not to fix, or at least improve, the bump steer problem. It entails making a new drag link for the steering with different dimensions and repositioning it at a lower level so that the tie-rods are parallel with the lower control arm.

Yesterday I went out to Corvair collector Dick Hull's place in Allyn, WA and pulled a couple of old drag links off of junker front ends out in the woods behind his garage. I brought'em home; removed the junk tie-rods, idlers, and bushings; and cleaned them up on the belt sander and in the blast cabinet.

Next up was to cut each one to one half of the length of the new drag length unit. From there I ground each end down to a point. Then I made a jig to hold the two end while I welded them together. I used the TIG to just fuse the two tips together, then worked across the "valley" with the MIG to build it back up. Each weld was ground and cleaned before laying down another bead with the MIG.

Here it is on the jig.


Here are the two tips, end to end.


Here is the finished weld after grinding.


Step #2 will be to build some strengthening rib and weld them on.

Step #3 will entail cutting, repositioning, and rewelding the drag link ends so that they return to the correct overall length and so that they move the inner tie-rod ends down the proper amount.


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser



Edited 1 time(s). Last edit at 08/22/2017 11:35PM by Jonathan Knapp.

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: August 23, 2017 10:24PM

Did a little more work today on the steering, cutting out and shaping the gussets to fit between the inner tie-rod holes in the drag link. The one you see above the drag link will go across the top. The one you see below it will go across the front face of the drag link, at a right angle to top one. They are made out of 3/16" by 1" flat stock. This will give a lot of rigidity to what is now a longer, and therefore more flexible, drag link center section.



Tomorrow I'll tack them in place with the TIG and then finish welding them with the MIG.

The next step will be to shorten the ends of the drag link to get the overall length back to the stock dimension between the Pitman arm and the idler and to be sure to get them welded back on at the correct angle. I'll have to think about how to do that...

I ordered a new bushing, sleeve and bolt from Clarks yesterday and new, shorter tie-rod adjusting sleeves from Speedway Motors.


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Date: August 24, 2017 04:47AM

Jonathon, are you using known dimensions or did you experiment and establish your own geometry? I love it! Thanks for sharing.

---------------------------------------------------------------------------------------------
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


Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: cepak ()
Date: August 24, 2017 06:12AM

I have no experience with this whatsoever, so excuse the stupid question.
Won't the geometry change once you add weight back to the front of your Corvair
to get back to the minimum weight in SCCA Street Modified class?


Tom Cepak
Fort Worth, TX

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: v8vair ()
Date: August 24, 2017 12:26PM

On your Drag link, I would cut it again and slide a sleeve over the tube , then position over the welded joint and weld.
There's a big load on the drag link cornering hard.
Mike

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: August 24, 2017 09:08PM

Johnny -

Steering geometry is very hard to graph in a complete sense. The steering arms move through an arc on a horizontal plane. The suspension parts move through an arc on a vertical plane (or nearly so, taking account of your caster). The Pitman arm and idler move through arcs that are on a different plane still which move the drag link down and forward as the steering turns away from straight ahead. It then moves it up and back as it moves back from a turn to center.

All of this is to say that I do not have some theoretical dimension for the steering geometry. As with many things in life, steering geometry is a compromise. The more I have changed things, the more I have realized what the factory's compromises, and priorities, were. As I have changed the front suspension geometry and the steering arm geometry, now I am running up against the limitations of the stock drag link geometry for bump steer. I am working from the premise that an improvement in bump steer performance is better than doing nothing, even though I may not end up with "perfect" geometry.

Right now, with my lowered suspension, the lower control arm is just about parallel to the ground when the car is sitting on the ground. (The lower control arms may actually point up a little bit at the outer end, but they are at the very least parallel.) This means that as soon as the suspension compresses at all, the spindle, wheel, tire, and (most importantly for our purposes) the steering are starting to move up and in on an arc toward the center of the car.

At the same time, the tie-rod sleeves actually point down (toward the ground) on the outer end. This means that as the suspension compresses and the outer tie-rod moves up, it does so on an arc that moves up and away from the center of the car (at least until it, too, becomes parallel to the ground and then it begins to move back toward the center of the car as it continues to move up). What this means for bump steer is that in the first bit of suspension movement during compression, the steering arm wants to move in with the lower control arm but the tie-rod arc has to push it out to follow its arc. Hence a lot of toe-out on bumps or under front end loading (carrying things in the trunk or, more important for racing, braking).

What my modification will do is two things: 1) create shorter tie-rod units that will more closely match the arc of movement of the suspension lower control arm, thereby reducing the change in toe during suspension travel; and 2) reposition the drag link to a lower position so that the tie rod units are parallel to the lower control arms, thereby eliminating the tendency for the tie-rods to push out on the steering arms during the beginning of suspension compression.

It will not be perfect, but these two modifications will move things significantly in the right direction.

Tom -

Not a stupid question at all. The best way to think about it however is to realize that, whatever the static position of the suspension, I am striving to reduce the amount of toe change during suspension travel. If the car is heavier up front and sits lower, the improvements in toe change through suspension travel (bump steer) will still obtain.

Here's a picture of the top gusset that I got welded on today. I should be able to get the front gusset welded on tomorrow.



Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: BobV66Vair ()
Date: August 25, 2017 09:10AM

Jonathan, really good information every time you post. Your suspension changes show just how smart an engineer needs to be to design these things. I saw once a planning tool that was made of flat pieces of Masonite cut to the dimension of the front end components. It allowed each to move by using some simple connectors at each point, matching the actual connection points. It was not perfect because it attempted to lay out the suspension on a horizontal table where the vertical plane was turned 90 degrees so it could lay flat on the table. It made it easy to see the movement of each component and, more importantly, how changes to any component affected the wheel/spindle. In the example, they wanted to change the way the spindle moved in turns, much as your working on. The device allowed them to try changes using the wooden component section before they made it out of metal. Just as your explaining, they had to make compromises in the components. They chose what would work best in their application and then fabricated the real parts. I wish I could find it, it was a good visual tool for us simpletons.

I look forward to hearing about how the car performs after it's done!

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: MattNall ()
Date: August 25, 2017 09:18AM

Plenty on Youtube

[www.youtube.com]





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: 283corsa ()
Date: August 25, 2017 08:32PM

Do you have a source for more rear windows, I am in Oregon and would like to buy at least one, thank you DAn

Options: ReplyQuote
Re: Subtracting Weight from the Autocrosser
Posted by: Jonathan Knapp ()
Date: August 26, 2017 09:40PM

Dan -

PM sent.


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

Options: ReplyQuote
Current Page: 4 of 5


Sorry, only registered users may post in this forum.
This forum powered by Phorum.