FED Build

[THE FRENCHTOWN FLYER]

I'll tell you a funny true story.
My friend and his wife raced altereds. At one point they had a new car built by a prominent local chassis builder. I went over to see it when it was done. He had welded the kingpin bushings in UPSIDE DOWN. I suspect he mail ordered a base axle and when it came in to the shop he welded on the radius rod batwings upside down and when he realized it he just said "F*** it" and swapped the spindles left-to-right. With such a messed up kingpin inclination angle the scrub radius was a mile outside of the tire contact patch. I explained to him he could have an evil handling car on his hands.
Well call me stupid. His wife won two IHRA Modified Eliminator championships with that car.

As a post script to the story she did end up rolling it in the lights. I do not know if the messed up front end geometry was a factor in the crash. I never spoke of the front end mess again.

I guess like the little girl with the little curl "... when it was good it was very, very good, and when it was bad it was horrid."

[denverflatheader]

Lynn - I would guess you meant 1.2 degrees "negative" camber with solid dragster style axle.  I forget myself which direction when thinking about negative and positive camber.  My thoughts here, for a race car with independent front suspension, 1.2 degrees positive camber good.  For your dragster with solid front axle, it will probably be 0 to 1 degrees negative camber (the top of the wheels tilt inward for negative camber).  0 degrees camber would be best considering rolling resistance. 

Drag strips are flat & straight, not like a typical roadway.  With positive camber, the wheels (steering) will have tendency to go in direction that has more positive camber on a flat straight road.  For example, if your left wheel has 0.5 degree positive camber and your right wheel has 1.5 degree positive camber, your vehicle may tend slightly right. 

However, the end result with your 60s style dragster with a skinny front tire like an Avon speedmaster, you will probably not notice any steering difference with a camber range between -1.5 to +1.5 degrees due to the minimum contact patch with the road surface.

p.s.  FTF - I've had a few messes in my projects too, some big and some little mistakes, some I laugh about, some not so much.

[lake_harley]

I actually checked on + and - camber before I posted and unless I'm thinking wrong about the sum of the angles involved I will end up with a bit over 1 degree positive camber (wheel tops further apart than the bottom). No matter positive or negative I would think any camber could cause a slight pull, right or left, depending on wheel loading and grip on the surface. I do plan to run a rounded tread type tire.

I don't propose to have any answers. I'm just plodding through and trying to learn along the way.

Lynn

[denverflatheader]

I'd heard story (friend of mine who raced at Lions in Long Beach) on reason dragster front axle had negative camber.  As 60s dragsters got longer and longer, plus wheelie bars, engine torque plus the longer chassis flexing when launching would lift and carry the left front tire.  The driver could still steer with the right front tire on the ground.  Their thought was starting with negative camber, the single right front tire going to 0 degree camber would be easier to steer, versus starting with positive camber and having more positive camber added at launch when the left front goes up and carried for short distance.         

Happy Thanksgiving to all.

[lake_harley]

Sounds like there's good logic in that idea.

Lynn

[JEFF/21C]

i've always use 10* inclination and 10* caster on all straight axle cars dirt,drag and ice except for fed caster was set at 12* camber varied 0*-neg. 1* alway handled well.

[lake_harley]

Still chipping away and making slow progress. I got the rearend and engine jigged up with an alignment bar on my chassis jig. I got the carrier bearings pressed onto my spool today after needing to make tooling for my press to seat them all the way. There always seems to be "just one more step" necessary to get anything done.

I guess I need to buy a dunce cap. I was going to remove my ring gear from the open carrier and didn't notice the giant "L" on the ring gear bolts indicating (thank you Mopar) left hand threads! I buggered up the threads in one of the holes and stretched out most of the bolts before I realized why they weren't loosening up. Doh! So, now instead of "wanting" a different ring and pinion, I "need" a different one. I'd perfectly happy with a used but useable ring and pinion for a 741 case (already have a coupler for 29 spline pinion) and would be interested in 3.23, 3.55 or 3.73 or other ratios that would work. Car is for bracket racing so optimal gear ratio isn't quite so critical. Let me know if you have something and please include price and photo(s) if possible.

Thanks!

Lynn
(573) 788-2574 Home/Shop
(573) 286-3335 Cell

[lake_harley]

I got a few other projects finished up (including my ring gear/spool issue from the last post) and now have a window of time to really make some progress on chassis building. I'm starting with the shoulder hoop and will be working from the back forward. I don't think I'll ever see the need to have my car certified since all I have in mind is bracket racing at unsanctioned tracks, but I'm pretty much following S&W plans as well as construction info from an AHRA rule book, which appear to be copied, from what I've seen, from NHRA. Remember I'm building a 10+ second 1/4 Mi. car but will only be running on potentially 3  local 1/8 Mi. tracks.

My understanding is that the chassis construction regulations/requirements pretty much stop at the mid-plate, or possibly at the front of the engine. Is that accurate? Believe me, I don't have anything crazy in mind, but does a builder have flexibility on chassis construction forward of the engine or mid-plate?

Lynn

[Finnish Fireball]

You got that right, only the cage and cockpit area matters. What comes to never needing a tag and only 10sec comments, I strongly recommend a second thought. Trust me there will be a day you want to go faster, we all have been there done that. There will also be a day when you try to sell the puppy. Hundred times easier with cert. And the list goes on, do it by the book at once. It's a lot easier now than upgrade later. 7.5 sec spec for mild steel is not that bad. It will cost you just as much time and money to fab an unsafe backyard hackjob as it does the other way, when you are starting from scratch.

[THE FRENCHTOWN FLYER]

^^^  X2

[lake_harley]

Thanks for the replies. I am building per chassis plans and using materials that should pass certification but I don't expect I would ever need it. You've answered my question and that is that certification pertains to only the cockpit/cage area. I thought I had read that somewhere but couldn't find it again.

Thanks.

Lynn

[wideopen231]

On specs. I bought a copy of certification spec for 35 bucks. Cheaper than having to change something later on. JMO

[lake_harley]

Got some tubing in today and to the naked eye it looked a little thinner wall than what I ordered. I de-burred the edge and checked the wall thickness. Yikes......010" - .011" under the "advertised" wall thickness! My long-time steel supplier said the steel industry is really a mess these days and I'd say there's no doubt about that. He's going to check other tubing in his stock to see if some is on spec. On the bright side I won't be needing that particular tubing for at least a few days, so I can continue some modest progress with what I have on hand.

I've been jigging up some of the cockpit area and bending tubing. Got far enough today to actually tack weld a few pieces together. Woo-hoo!

Lynn

[THE FRENCHTOWN FLYER]

I had to go up a gauge size to insure the tube I used met NHRAs spec of .120" min for mild steel.

[fuel749]

Got some tubing in today and to the naked eye it looked a little thinner wall than what I ordered. I de-burred the edge and checked the wall thickness. Yikes......010" - .011" under the "advertised" wall thickness! My long-time steel supplier said the steel industry is really a mess these days and I'd say there's no doubt about that. He's going to check other tubing in his stock to see if some is on spec. On the bright side I won't be needing that particular tubing for at least a few days, so I can continue some modest progress with what I have on hand.

I've been jigging up some of the cockpit area and bending tubing. Got far enough today to actually tack weld a few pieces together. Woo-hoo!

Lynn

4130 or mild?