"SUPER MODERATOR" Serious question. I tried to duplicate your diagram accurately and unless I am missing something, doesn't the diff. in radii yield bump steer?
Correct,...sometimes! My 315 Dodge Poly would not accept my 325 Dodge Hemi heads w/o a modification. If anyone wants to explore this subject further, let's get the following thread resurrected. https://www.jalopyjournal.com/forum/social-forums/early-hemi-tech.234/
yes you are missing something. you need to go back and read Pete's thread (I know it is 15 pages) there is where it is explained. here is a copy of the pete and jakes catalog. this may explain it for you
Based on my limited understanding of Pete Eastwood's wonderful cowl steering explanation, I believe that it is not simply different radii that creates bumpsteer. It is intersecting arcs. In the diagram you drew, those arcs will forever be perfectly co-eccentric, which will not cause bump steer
It is the centre of the radii that matters, not the length. As long as the centres are very close the length makes no difference. That is the whole ‘core’ problem of the bump steering issue: different centres of the radii.
the problem is @wstory used the wishbone to axle area as one of his arcs. this is incorrect. both pivot points are where the drag link connects. it is spelled out in the pete and jakes catalog pic above and also in Mr Eastwoods thread I referenced earlier. 15 pages
Well boys and girls, I've decided to do it again. I've carefully read and studied all the thoughtful input. Thank you all for your observations, opinions, cautions and criticisms of my reckless disregard for life and limb. I respect and accept that Henry did a pretty good job and messing with his geometry and physics has it's risks. However,....that's what we do, right? That said,...I got the car on the road with cowl steering in late 2015 with 88,000 miles on the clock. Shortly afterward came the Hemi and the Folding Top among other modifications. The car now shows 155,000 miles. That's about 67,000 with the cowl steering and the basic concept has proven sound. Soooo,...I am planning another cowl steering project for a Model A, the current the beneficiary of my need to mess with stuff. The Ford box has worked quite satisfactorily. However it requires "reversing" the gears. I understand that an early BMW box as well as a 70's Mopar box are good candidates as they do not need to "reversed" box. If anyone here has opinions about either of those pieces of hardware, I'd certainly welcome your input. In the meantime here's a pic of the car as it sits now. And, here's the car that'll receive the cowl steering transplant,....eventually! And the threat, https://www.jalopyjournal.com/forum/threads/poly-begets-a-hemi-begets-a-model-a.1194565/page-16
Are you aware that both midget and sprint car steerings can be had in power types with both adjustabe****ist and feedback? A street type worm and roller steering is not a good choice for a performance car steering because as it goes away from center, it becomes floppy due to increased clearances between the worm and roller. This is by design. A race car steering is worm and gear so clearances are constant throughout the range. You haven't lived till you have driven a car with a race type power steering.
Ok, .... I do believe somewhere... I remember that a early VW bus had the rite workings...an is aluminum...
Thanks boys for the input, always appreciated, makes me a little smarter,...I'd like to think. A friend has a power cowl steering unit in his 32 Roadster. For me "power" requires another system (hydraulic) and friend says it generates heat under his dash. Also, cost is a factor I must consider. Another friend has an early VW commercial "flat bed". I'll definitely check it out!
i wonder if ryan's brother paid attention to ol pete's rant on cowl steering or the rolling bones guys for that matter.
The Mopar box is about the burliest OEM box you can use for this. It can be found in steel OR aluminum. It would be a good choice for the weight of that hemi
Everybody seems to ignore the science and lets the "cool factor" take precedent. They get away with it because most of these cars have less than 2-inches of travel, so bump steer isn't as noticeable. But it's there. Don't believe me? Draw the arcs on any of these cars using the illustration Moriarty posted and you can see for yourself. And just to rant, but how does one justify a BMW or VW steering box as being "traditional"? Because it's cowl steer? Imagine how a thread about installing '70s BMW disc brakes on a '32 roadster would go over...
And not to pick on the OP, I dig your roadster and the mileage you've accrued is very respectable! Good for you! But, I like the discussion and sometimes can't help but to play the devil's advocate as it were.
Well boys,....in spite of the input, I'm going forward with another cowl steering project. If it works as well as the previous exercise, I am a happy camper! If not and I am disappointed with the results,....I will share. I am currently "inclined" toward the Mopar unit, especially if I can score an aluminum unit. 'Tho the Mopar unit does not require that it be "reversed", it will require an extension to the sector shaft. A friend has done that, as well as engineering a new pitman arm attachment and I will be checking his solution in the next few weeks. Also,...my engine is a Baby Hemi, 1955 Dodge, 270 inches and weighs no more than a SBC.
Excellent... There is a fella on here that cast aluminum part's, And I believe offered the cowl part's for Mopar steering.. His handle has 4speed In it, Rochester NY
Here's the latest on the Model A build. Tackled the headers recently as it was a significantly ambitious project with modest out of pocket cost. Pretty happy with how they turned out. Next is decision what to tackle next. Aside from cowl steering, pedals, fuel system, cooling system,... not to mention how to get a blown engine running (w/o exploding) are significant projects to address. Check out the thread https://www.jalopyjournal.com/forum/threads/poly-begets-a-hemi-begets-a-model-a.1194565/
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