new front hubs

[Whiskey Joe]

I'm going to be building new front hubs for my rail, so that I have an Ackerman steering setup, and also try to add a little caster.

Problem is, I have zero bumpsteer right now, and if i go messing with the steering TRE in relation the the outer joints of the A arms, I'm afraid I will create a bumpsteer issue.

here's a few pics of my existing setup and a crude drawing of what i plan on building for a hub.

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another question i have, since i can't change my caster without building new A arms and cutting up my front end, does anyone see a problem with adding a little caster to the hub?

instead of welding everything center inline with the spindle, i can put the upper and lower heim brackets slightly to the front of the center, so the spindle would be behind the pivot.

[bdkw1]

You don't need to build new arm's. Just weld another threaded bung onto the lower arm the extend it the needed amount. With the horizontal mount hiems and no mis-alignment spacers, I can't see you getting much travel out of that set-up before something binds badly.

[PhillipM]

Shifting it behind the pivot would give you mechanical trail, but no caster change.

You need to add some stiffeners to that mounting face though, it must flex all over the place like that - in fact you can see where it's tweaked/bent already.

[deaner]

Cool looking car! What are the front hubs off of? It looks like you have excessive tire scrub and zero caster, must be a handful to drive. If you remake the spindle to add caster (a must in my opinion), you should eliminate some tire scrub while you are at it. You need to get the lower arm longer/top arm shorter or both and make the spindle to match. I'd consider making new upper A-arms as well as spindles.

[darwinpayne2000]

I'm not the front-end expert, but a picture (or three) is worth a thousand words.

The front end on my buggy is adapted from the Shredder II plans.



It's not real clear, because the rack-and-pinion box kind of hides the bolt, but the A-arms are unequal on both the frame mount and on the spindle, with the top A-arm shorter than the bottom A-arm. If it's designed right it will give you positive camber change as the suspension compresses. The A-arm and spindle design also give you king pin inclination, which is something you want.



This picture shows the wheel side and the unequal A-arm is a little more obvious. Also, if you draw a line between the upper and lower heim joints, that shows the king pin inclination (KPI) built into the front end.



This picture shows the caster, where the lower arm is forward from the upper arm. My caster is based upon the calculations that Scott lists in the Shredder II plans. You could add caster to your setup by making your A-arms a little narrower, then off-setting them with spacers. That would be a fairly easy modification, I think. Or, while you're at it, you could also rebuild your front end to not only add castor, but throw in some positive camber and some KPI to help it steer better in the corners. Just a thought.

This may help others reading this thread visualize what people are talking about when they mention unequal A-arms, KPI, caster, camber, etc. It took me a while to understand how all this stuff goes together to make an awesome front end design or, in my case, a "good" front end design. "Awesome" is reserved for the next build.

Edit:

I forgot to address your original question about your Ackerman. I'm a big believer in "try it". If it doesn't work, rebuild it. I don't think that moving your steering arm out will increase the bump steer, but adding caster will also mitigate bump steer. Maybe must move your top A-arm back, move your steering arm out and see how it handles.

Your front end is a very basic straight-forward design so anything you "add" (e.g Ackerman, caster, KPI, camber, etc) should only make it better, not worse.

[Whiskey Joe]

it really handles quite well.

i will be building new hubs, i will be putting the heims verticle with high misalignment bushings, they're already on their way.

i probably won't be building new upper arms, at least not right now, this is only 1 of many winter projects.

although i will add the ackerman setup. right now i almost have a reverse ackerman setup, its not bad, but the outside tire turns sharper than the inside, which is interesting in the sand, it almost carves a groove and just follows it, but i think it can be better.


the main reason i'm flipping the heim joints is from the excessive load the front engine V8 puts on them. they're not designed to be horizontally load bearing.

i've broken a couple, but its been a while.


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https://www.youtube.com/watch?v=pA9kfD1FYD4

a little hill climb, flogging across the flats and a whoop road @ 4:45



@phillip, that part of the hub isnt bending, the way my dad made it, he cut a piece of channel iron and welded flat stock in for the steering tab.

@deaner, thanks, and they're hubs off of an old Nash Rambler. just removed all of the drum brake hardware. Our newer buggies all run rear hubs from mid 90's front wheel drive GM cars, like a lumina or olds cutlass
IIRC they're already a 5x114.3 (5x4.5) bolt pattern
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[Whiskey Joe]

Am I incorrect in assuming that high misalignment bushings are supposed to allow greater movement in degrees for your heim joints?

Just got mine yesterday, I ordered 3/4-1/2 bushings to get the optimum amount of movement.

The heim moves exactly the same, if not even a little less, WITH the bushings, as it does without them.

The only benefit I'm seeing is that they create space between the bracket and heim, to allow bindless movement.

[bdkw1]

Picture of spacers?

[Whiskey Joe]

Not sure how to post pics from my phone. I'll post up later


edit: here's what I ordered

Look at this on eBay http://www.ebay.com/itm/390016679735

[bdkw1]

Yes, those should allow for more movement. If they are poorly made and hitting the race, they will bind, Does the radiused lip go into the race or does it hit?