Rack And Pinion exploration

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Byron510
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Post by Byron510 » 27 Oct 2007 20:35

We're all ears!

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Post by 510rob » 28 Oct 2007 00:42

Is it from a Spitfire?

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Post by benz-tech » 28 Oct 2007 08:59

i'm only keeping it a secret because i don't know the ratio or exact width yet. i only want to post accurate info.

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steering box ratio?

Post by benz-tech » 29 Oct 2007 09:02

Info is trickling in on the rack I'm looking into, I have the ratio, 117m of rack movement for 3 full turns. this roughly translates into 1.53" movement of the bar per turn of the head. my last real rough measurement on my box was 1.75" of pitman arm movement per turn of the steering wheel. can someone verify?

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S15DET
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RE: steering box ratio?

Post by S15DET » 31 Oct 2007 05:42

FYI, the MR2 rack moves 1.68" for one turn of the wheel.

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Post by S15DET » 05 Nov 2007 06:48

Here's photos of the completed (mostly) MR2 rack mounting, before paint.
Attachments
PB022880-1.JPG
PB022881-1.JPG
PB022878-1.JPG

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Post by benz-tech » 07 Nov 2007 18:00

well, here's the deal on the fiat x1/9 rack: when taken apart the pivot to pivot is about 20.75". too wide obviously but slightly narrower than the mr2 rack. the way the boots fit on the housing fooled me into thinking it was narrower. the other bummer is the ratio, at 1.5" per turn it is a bit slower than the 510's approx 1.75" per turn. :(
as far as the size goes, it will just barely fit around my left bank header but it looks like it will and it is hands down the smallest rack ive seen in the last few weeks. it also looks like it could be shortened easily buy pulling the bar out and having it shortened and shortening the housing. but if that stuff can be done to a fiat rack why not a mr2 rack and then have the better ratio. I am very willing to lend this out to anyone wanting to mock it up. the hunt contiunes. i'll try maval steering to see how much a custom would set us back.

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S15DET
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Post by S15DET » 08 Nov 2007 04:43

I'm glad we're all looking into this, great job! Good info benz, thanks. So the hunt continues... A custom built unit may be the only solution? There's lot's of custom rack companies out there, so it'll come down to price at some point.

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sdterrible1
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Post by sdterrible1 » 08 Nov 2007 08:39

i will be sending my rack specs that i need for my car tomorrow to Unisteer.
I will let u all know what they quote me for a price. Hopefully its not to much coin!
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S15DET
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Post by S15DET » 08 Nov 2007 09:56

What will you request in terms of ratio?

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Post by S15DET » 08 Nov 2007 09:58

And length, for that mater? Are you going to try to match the width of the stock inner tie rod pivot points? That's probably a good start, but for a lowered car it may not be optimal.

We need one of you SAE students to determine the correct width, make it a class project.

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Post by sdterrible1 » 08 Nov 2007 10:12

i have not done all my homework yet i need to take all the measurents tonight. I have the datsport x member which puts the pivot points at 17.5 total width. Which is quite abit narrower then the stock one. Man this stuff is hard to fugure out!
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Post by benz-tech » 08 Nov 2007 17:59

talked to maval today. a custom rack for 1 person is around $500. thats the bad news, now the good:
any pivot-point width we want.
nearly any ratio we want - anywhere from 2:1 to 6:1 (i don't know what that means either, just what he said) basically slow to really fast...
any inner tie rod length and possibly thread we want. (his are 14mm x1.5 and could be madelong enough to just thread into our outers) whats our pitch?
low profile head 4" x4" square.
price would drop to around $300-350 per unit if we get a group buy- at 10 or above. thats a WHOLE lot better.

before we have a "are you in or are you out?" group buy discussion, we need to have exact specs neccessary, not what i've done so far with a tape measure. I think we would all agree on a faster ratio, but how fast?
also need overall length of the threaded part of the shaft goin into the outer tie rods.
the only other issue i can think of is that some company does have a rack kit for a lot of money and are we just redundantly engineering what they have already done. - can't remember who that was.

then there is the steering column issue. it'd be great if we found one solution and everybody used it. there is power (and price reductions) in numbers. if we could get the locations the same for SR's and L's the linkage could all be the same just mounting to the crossmember would be different.

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Post by 510-Trevor » 08 Nov 2007 22:44

benz-tech wrote:...the only other issue i can think of is that some company does have a rack kit for a lot of money and are we just redundantly engineering what they have already done. - can't remember who that was. ...
like these guys? http://www.dgrfabrication.com/
1972 Yellow 4dr

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Post by zootowndime » 08 Nov 2007 23:58

I was just trying to quckly browse through this thread, but i couldn't find it. I think someone had already mentioned dgr and the owner told them that they pretty much use the mr2 setup.
I would be very interested in the group buy but i agree that this must be the ulitmate rack! What the specifications of the rack might be i am not sure, but I am glad there you guys out there that are good with numbers.
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