How fast is your rat

It looks like only one of the 4 pics I tried to post showed up this morning. Castor angle never even crossed my mind. I think I was so shocked at how stiff the front end was, and have been focusing on that lately. I guess Ill dig out my angle guage and see where I'm at and start from there. Hopefully I can get the angle I need with a hairpin adjustment. Thanks for the input

Your hairpin looks quite long and thin. Could be, you're suffering some deflection and harmonics, like a tuning fork.

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Yeah Dr. C I've taken that into consideration a couple times. I'm going to check the castor angle when I get home from work and at least see where I'm at. I honestly wouldn't think I could get the angle I want (8-10 deg from what I heard) if it's at 0 or negative by adjusting the hairpins??? I might have to start cutting and welding. All the input is great and it's a great forum, to get the wheels rolling and creative juices flowing

Like you say, if you have zero or negative caster, I doubt you'll get 8 - 10° positive by hairpin adjustment, working against the spring and its perch.

Try those pics again so we can see what you're fighting...

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More pics hopefully

Pic

I'm having trouble posting them all at once

Hard to tell from those pics but post 26 looks like the caster is zero or possibly negative....Put the inclinometer on it and take a measurement.

So many variables available here, camber, castor, toe in/out, tire pressures, wheel offset from the king pin centreline, spring strength, bump steer, slack in steering linkages etc etc.

I've seen some horrendous set-ups that seem to work fine, and some state-of-the-art that ran like crapola.

When I built my first car I went for a test drive....and nearly drive it home to cut it up! It was so hard at the front, soft at the back, jumped all over the road, wandered around, noisy as hell etc. I persevered at dropped 10psi from all the tires, had a stiffer rear spring made, took a leaf out of the front semi-elliptic springs and it was not too bad eventually. The bump steer was always there, but never dangerous.

I did find that the faster I drove, the better it rode! 100mph on the free-way it drove smooth, tight and straight

I've thought about redoing it with a simi elliptic King Herold. I think they look good if done right and the few I've seen the owners love them. Yeah smallfoot I kinda thought the same thing when I was looking at that pic before I posted it. I'll measure it when I get home. If I can find my tool, I kinda think my neighbor across the street has it tho. It's always ironic how you may have something but when you need it you let someone barrow it

Ken47int said:

I've thought about redoing it with a simi elliptic King Herold. I think they look good if done right and the few I've seen the owners love them. Yeah smallfoot I kinda thought the same thing when I was looking at that pic before I posted it. I'll measure it when I get home. If I can find my tool, I kinda think my neighbor across the street has it tho. It's always ironic how you may have something but when you need it you let someone barrow it

Click to expand...

I never ever let anyone borrow my tools unless I have a spare "junk" one of the same thing just for that instance.

Well I found my tool and at the ball joints with air bags up to normal ride height the angle is about 5 deg. I was kinda hoping for less and possibly a better answer. So now I got to decide if it's worth it to chop and redo it to get to extra 3-5 deg that might be the missing link. I'm more then likely going to do it but damn it's nice out so I'm just going to run it and save the project until Sunday or maybe next weekend

I would try to get those hairpins adjusted to make a little more caster. They look like there is still some adjustment room. I'm running at 7 degrees and mine rides nice. I suspect other problems.

Yeah, smallfoot I agree. I'm out driving around now and stopped to get something to eat. I'm thinking I might just redo the front end completely. Start with a new beam,bat wings, hair pins or a four bar set up. I might possibly just make a new frame as well

5 degrees isn't horrible, depending on a lot of other things. I'm running 9-9 1/2 and I think it's too much but would have to bend my trailing arms to adjust it. It drives fine but the steering is pretty heavy with that much.

Another thing you can check is your wheel offset. If you can imagine your kingpin being long enough to reach the ground. picture where it would intersect the tire the closer to the center of the tire the better. thre closer to the inside of the tire it is the more it will exaggerate a bad condition. also if the kingpin angle (Caster) isn't the same on both sides it will give you trouble from a pull

Ken47int said:

Yeah Dr. C I've taken that into consideration a couple times. I'm going to check the castor angle when I get home from work and at least see where I'm at. I honestly wouldn't think I could get the angle I want (8-10 deg from what I heard) if it's at 0 or negative by adjusting the hairpins??? I might have to start cutting and welding. All the input is great and it's a great forum, to get the wheels rolling and creative juices flowing

Click to expand...

Looks to me like there is not a lot, if any at the moment. Does it self centre when you make a fairly tight turn then let the wheel go?

You could adjust the hairpins, but you'll find your spring is then twisted.

kenny c said:

Another thing you can check is your wheel offset.

Click to expand...

I built a car years ago, a real abomination, using a solid steel tube Jeep front axle, and that would shake the front wheels horrendously some days. I never did cure it, but years later I looked at the car again, a friend now owned it, and realised my wheel centrelines were about 10" offset outwards from the king pin centre line.

Somehow the spacers and adaptors and stuff that came with the axle made it so.