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Moist Lightning

Center Take-Off Rack & Pinion

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So ive looked through the forms on R&P setups and it looks like the center takeoff was brought up but the only option mentioned was an expensive custom rack. So I’ve been doing some research and think I’ve come up with a solution. I'll post what I’ve found below and you guys can let me know what you think / help me perfect the design.

 

So first off the cars I have found with center takeoffs are

Front Steer

Dodge Intrepid

Chrysler Concord

Eagle Vision

 

Rear Steer

Saab 9000/Early 9-3

Honda civic

Cavalier

 

From a geometry perspective it seems that most stock center takeoff are designed for mcphersons so the actual pivot points are close to the center like the pic below.

 

qwACEvo.jpg

 

However there are plenty of aftermarket center takeoff that have a extension bar (for lack of a better words) that moves the pivot points further out as seen below.

 

FtMQ5mk.jpg

 

Lastly it is quite common to modify the stock center takeoffs to look like one of the aftermarket ones. Just Google cavalier rack and pinion.

 

AhQzJ6x.jpg

 

PCZR24h.jpg

 

Can I post links to other websites to reference builds I have found? If so I will edit them in here:

 

So the idea would be to modify a stock center takeoff to have an extension bar that connects the two outer tie rods together. Alternatively, if the steering box could be replaced or modified into just a idler arm then you could attach the current center link to the rack.

 

Right now my biggest concern would be flex in the extension bar due to the length needed. From a different thread the distance needed was quoted at 22.75"

 

So let me know what you think.

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Unless you mount it behind the front wheels the steering will be reversed. Left will turn right.

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Unless you mount it behind the front wheels the steering will be reversed. Left will turn right.

 

Hmm I thought it was a front steer rack. Isn't the problem not where you mount it but whether or not you would have to flip it to get it to steer in the right direction (causing the input shaft to be on the wrong side)?

 

Edit: I got what you mean now, its not where its mounted but where it connects to the spindle. Let me think this through a bit and ill update.

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The rack needs to be rear steer or front steer depending on your knuckles, whick could possibly be flipped depending on the vehicle.

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   Could you please post links to the builds you have found ?? And maybe the actual years of Saabs and cavaliers they used ? i Rockauto-ed those cars and pictures showed "normal" rack oics. 

 

    I'm curious for other projects i have going.

 

 

If it matters Ford thunderbirds/fairmont type vehicles about 1978-1981 use front turn R n P steering but they are pretty wide vehicles

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FtMQ5mk.jpg

 

I had a non power version of this rack - never knew the manufacturer. Who is it?

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So i found the following front steer racks with center take off are Dodge Intrepid, Chrysler Concord, & Eagle Vision.

So now that that is fixed any other concerns or problems you notice?

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   Could you please post links to the builds you have found ?? And maybe the actual years of Saabs and cavaliers they used ? i Rockauto-ed those cars and pictures showed "normal" rack oics. 

 

    I'm curious for other projects i have going.

 

 

If it matters Ford thunderbirds/fairmont type vehicles about 1978-1981 use front turn R n P steering but they are pretty wide vehicles

 

I found some front steers thanks. Forget the years just search for the cavalier rack instead its the most common one used.

 

http://bloom.is-s.com/~ranchero/tech/steering/Rack-n-Pinion.shtml

http://www.crankshaftcoalition.com/wiki/Swapping_to_rack_and_pinion_steering

 

FtMQ5mk.jpg

 

I had a non power version of this rack - never knew the manufacturer. Who is it?

 

I think its unisteer - cost upwards of a grand. thats why im looking to build something. 

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Hmm I thought it was a front steer rack. Isn't the problem not where you mount it but whether or not you would have to flip it to get it to steer in the right direction (causing the input shaft to be on the wrong side)?

 

Edit: I got what you mean now, its not where its mounted but where it connects to the spindle. Let me think this through a bit and ill update.

 

 

The rack needs to be rear steer or front steer depending on your knuckles, whick could possibly be flipped depending on the vehicle.

 

I think the 620 knuckle is part of the hub. Maybe switching L to R? But then the steering would go through the oil pan and then it would be something else and then something else....

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So i found the following front steer racks with center take off are Dodge Intrepid, Chrysler Concord, & Eagle Vision.

 

So now that that is fixed any other concerns or problems you notice?

 

It looks like the next step is getting the overall length of the rack and seeing if it is going to stick out past the frame too much. i'll look into it and update after. let me know if you notice anything else.

 

Edit: there all 35" long, trucks under a ft of snow so might be a bit before I measure the frame. anyone know if thats gonna fit?

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I have replaced many inner steering coupling bushings on Dodge Intrepid/et al others...

 

Everyone of these racks is mounted to the firewall. Not front steering.

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I think most R&P would be for FWD. It's just easier.

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I meant the rear mount location....

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I have replaced many inner steering coupling bushings on Dodge Intrepid/et al others...

 

Everyone of these racks is mounted to the firewall. Not front steering.

Yes they are mounted on the fire wall but they are front steer. 

 

You can see that the pillars are really far back.

 

7t4WNX3.jpg

 

Here's the diagram.

 

zNUVckl.jpg

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You would have to increase the mounting spacing between the inside tie rod ends

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I don't know if anyone has mentioned it, but the distance between inner tie rod ends on the new rack needs to be the same as the distance between inner tie rods on the stock tie rod setup or you will create a bumpsteer condition. You could modify things to get it right, but it would be easiest to start with the proper width rack.

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I don't know if anyone has mentioned it, but the distance between inner tie rod ends on the new rack needs to be the same as the distance between inner tie rods on the stock tie rod setup or you will create a bumpsteer condition. You could modify things to get it right, but it would be easiest to start with the proper width rack.

This has always been the confusing part of center mounted tie rod R&P. The civic one clearly has pivots only a couple inches apart. so did they make up for that design flaw with other suspension engineering?

 

Regardless i have wondered about machining big ole extension bars that thread into the center mount and place the pivot out at the standard location.

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This has always been the confusing part of center mounted tie rod R&P. The civic one clearly has pivots only a couple inches apart. so did they make up for that design flaw with other suspension engineering?

 

Regardless i have wondered about machining big ole extension bars that thread into the center mount and place the pivot out at the standard location.

Isn't the Civic rack also connected to the strut tubes? The distance between the inner/outer tie rod ends is probably close to/the same as the LCA inside pivot to lower ball joint distance, and the two are likely close to parallel throughout their swing, save for fore/aft positioning to account for Ackerman angle
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This has always been the confusing part of center mounted tie rod R&P. The civic one clearly has pivots only a couple inches apart. so did they make up for that design flaw with other suspension engineering?

 

Regardless i have wondered about machining big ole extension bars that thread into the center mount and place the pivot out at the standard location.

 

I don't know if anyone has mentioned it, but the distance between inner tie rod ends on the new rack needs to be the same as the distance between inner tie rods on the stock tie rod setup or you will create a bumpsteer condition. You could modify things to get it right, but it would be easiest to start with the proper width rack.

 

I guess i didn't explain that well enough in the first post.

 

The stock center takeoff are designed for mcphersons and the geometry(center pivot points) won't work with double wishbone.

 

We are just using the center take off rack and pinion to create something similar to the unisteer.

 

You have to build a new mount and extension bar that attaches to the rack where the tie rods use to connect.(if you remove the intrepid tie rods and mount from the rack you can then bolt the extension bar to it)

 

400px-Center_take_off_pics2.jpg

 

This build is almost exactly what im talking about. http://bloom.is-s.com/~ranchero/tech/steering/Rack-n-Pinion.shtml

The civic build - http://www.fordmuscleforums.com/all-ford-techboard/560058-another-crazy-idea-honda-civic-center-take-off-unisteer-rack-pinion.html

 

The extension bar needs to be 22.75" 20" the length of the stock 620 center link. as i mentioned earlier my only concern would be flex in the bar due to the length.

 

That is why i also suggested converting the steering box to and idler arm. then you just attach the center link to the rack and mount the rack to the cross member right behind the center link.  Never mind the arc of the idler arms would make the center link pull away from the rack.

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Yes they are mounted on the fire wall but they are front steer. 

 

You can see that the pillars are really far back.

 

7t4WNX3.jpg

 

Here's the diagram.

 

zNUVckl.jpg

 

Touche'

 

 

I don't make it a habit to be well versed on things having to do with Intrepids.

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Longer tie rods, say, from the center would be better than the stock ones. If they were infinitely long there would be infinitely small bump steer.

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Longer tie rods, say, from the center would be better than the stock ones. If they were infinitely long there would be infinitely small bump steer.

No. Longer tie rods means less radial movement of the outer tie rod end through the suspension travel compared to the radial travel of the LCA. Bump steer.

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I hadn't ever researched anyone making an extension bar to create the proper tie rod placement. I've discussed this idea in other threads, but never seen that first link you posted. I think it's a fantastic idea.

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