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Old 08-01-2017, 07:09 PM
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Need to shorten rack & pinion 12".

Here is my latest purchase of a rack and pinion steering unit from a 1992 Dodge Dakota. It's going in a 1991 Chevy S10 frame. I need to take out a total of 12" from the overall width. The stock unit is 57" in width. The Chevy S10 measures 45" in width. Can I just cut out 6" on each inner tie rod and weld it back together using some strong hollow pipe as a brace?
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Old 08-01-2017, 07:51 PM
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I'd cut more threads and then remove the amount you don't need.
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Old 08-01-2017, 09:31 PM
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Before you get to far into this....

Are the pivot ponts of the rack inner tie rod ends, where they connect to the ends of the piston in the rack, the same distance apart as the lower control arm mounting bolts on the S-10 Frame?? If not, you are creating a bad bump steer situation.

If that is OK, I'm with Johnsongrass1, just shorten and re-thread the intermediate tie rod shaft.

A Fox body Mustang(1979-1992) might be a much better fit as far as inner pivot width matching the control arm to frame attachment width. Or the good old Mustang II/Pinto rack.

I drive a 2wd Dakota daily, and my Dad has had several S-10's, one with a V8 swap.....and my gut instinct is the Dakota rack is much wider at the pivot points that the S-10 Lower A-arm mounts are apart.....which means bump steer change/reaction and squirrelly handling is going to be pretty severe.

Mustang II rack is 45" wide .....worth a closer look.
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Old 08-02-2017, 07:59 AM
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Eric is dead on... You are in for a wild ride if you don't pay attention to the design details when swapping to a rack. There is a lot of design work involved in doing this CORRECTLY...
Look this over and get back to us.
Technical Articles Steer
You HAVE to follow these guidelines to make a rack swap worth the cost and effort. If you can't do that then you should rethink the swap.
Mark
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Old 08-02-2017, 09:07 AM
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Another problem with a lot of R&P swaps end up being a reduced turning radius. A lot of R&Ps don't have enough travel.
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Old 08-02-2017, 06:40 PM
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Doing my homework - rack & Pinion

Guys,
Thanks for the timely response to my question about shortening a rack & pinion. I spent the best part of the day just measuring stuff. I went back and read the article on bump steer. I thought I had a grip on bump steer and Ackermann but I think I'm still learning. So then I measured everything I could on the S10 and things got confusing in a hurry. I know the tie rod length should be the same length as the lower control arm length to eliminate bump steer, but I was never able to get a measurement that confirmed that. For example the S10 has 16" lower control arms and has 18" tie rods. The distance from the center line of the chassis gives me 2 different numbers. I guess you have the paper world and then the real world. Nothing relates back to the book on bump steer.

I thought about scrapping the Dodge Dakota R&P but then I Googled dimensions for a Mustang II R&P and I was surprised that some of the characteristics for the Mustang were the same for the Dakota. Example: the length from inner tie rod 2 inner tie rod for the Mustang was 24", strange but that's the same distance for the Dakota. I had to remove the boots from the Dakota to prove it. Now I'm really confused! Now I don't see any advantage to use a Mustang II set up.

I'm almost tempted to install the Dakota R&P, shorten the tie Rods and just see what kind of squirly steering I get. I guess I could always change it later. I feel like I'm in the middle of a crap shoot! Dammit!!
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Old 08-02-2017, 07:43 PM
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Can I ask why you want to put a rack in the S-10??
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Old 08-02-2017, 09:25 PM
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Ericnova72,

I'm building a RAT 1948 Ford truck F100 using a 1991 S10 frame. I will be running a 2003 Chevy lm7 5.3l V8 5 speed. I will need a lot of radiator which will go inside a 1932 Ford radiator shell, which just fits between the frame rails. The current steering box is in the way. This rat will have no hood or fenders, just an exposed engine, radiator shell, cab and a make shift bed. It may be a rat, but I still want it to have a clean look up front and I didn't want the steering box to even show.

de_greaser
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Old 08-02-2017, 10:50 PM
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Wiki info

here is some rack info . could you swap in some rear steering arm spindles and have the rack under the radiator ? ?

http://www.crankshaftcoalition.com/w...inion_steering
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Old 08-02-2017, 11:07 PM
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Quote:
Originally Posted by de_greaser View Post
Guys,
Thanks for the timely response to my question about shortening a rack & pinion. I spent the best part of the day just measuring stuff. I went back and read the article on bump steer. I thought I had a grip on bump steer and Ackermann but I think I'm still learning. So then I measured everything I could on the S10 and things got confusing in a hurry. I know the tie rod length should be the same length as the lower control arm length to eliminate bump steer, but I was never able to get a measurement that confirmed that. For example the S10 has 16" lower control arms and has 18" tie rods. The distance from the center line of the chassis gives me 2 different numbers. I guess you have the paper world and then the real world. Nothing relates back to the book on bump steer.

I thought about scrapping the Dodge Dakota R&P but then I Googled dimensions for a Mustang II R&P and I was surprised that some of the characteristics for the Mustang were the same for the Dakota. Example: the length from inner tie rod 2 inner tie rod for the Mustang was 24", strange but that's the same distance for the Dakota. I had to remove the boots from the Dakota to prove it. Now I'm really confused! Now I don't see any advantage to use a Mustang II set up.

I'm almost tempted to install the Dakota R&P, shorten the tie Rods and just see what kind of squirly steering I get. I guess I could always change it later. I feel like I'm in the middle of a crap shoot! Dammit!!
That article is overly complicated in the real world. Almost all cars have some kind of bump steer because it's very difficult to get zero bump the entire amount the suspension moves up and down as well as the spindle moving back and forth and package it all up nicely. Maybe dedicated race cars but I'd say street cars with a defined packaging criteria is very difficult. How much bump and when is what matters most. Look at this way, The spindle and attached steering arm travel in an arc as the suspension articulates up and down. If you can get the outer tie rod end to travel in the same arc bump is minimized. If your suspension is only moving up/down 4" total, 2" up and 2 down, work on minimizing bump in that range. .020 in 4" of bump doesn't make a hill of bean on a street car.
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Old 08-03-2017, 04:04 AM
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Quote:
Originally Posted by johnsongrass1 View Post
That article is overly complicated in the real world. Almost all cars have some kind of bump steer because it's very difficult to get zero bump the entire amount the suspension moves up and down as well as the spindle moving back and forth and package it all up nicely. Maybe dedicated race cars but I'd say street cars with a defined packaging criteria is very difficult. How much bump and when is what matters most. Look at this way, The spindle and attached steering arm travel in an arc as the suspension articulates up and down. If you can get the outer tie rod end to travel in the same arc bump is minimized. If your suspension is only moving up/down 4" total, 2" up and 2 down, work on minimizing bump in that range. .020 in 4" of bump doesn't make a hill of bean on a street car.
Agreed, minimizing bump is the goal which is where the "design" side of doing this swap comes into play. Just grabbing any old rack off any junk car or truck is not going to get it done.
I would rather see the stock box sitting there then a cobbled steering system that will never work well. There is merit in getting the "look" you want but I draw the line when it comes to safety and function. JMHO.
Mark
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Old 08-03-2017, 08:05 AM
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Shortened rack

I narrowed the rack on my 33 Willys by 8.5 inches. To do it correctly and preserve the correct pivot points the rack itself had to be shortened. To do this the rack had to be withdrawn from the housing, cut and rethreaded. The machine shop that did it wanted to do the cutting as well as threading because of a possibility to work hardening the rack material. The car drove wonderful with no bump steer and even had a very short turning radius. Note this can only be done on a non-power rack. Sometime back I remember seeing ads for a company that would cut down a rack to your specs.
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Old 08-03-2017, 08:29 PM
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timothale,

I'm not sure what your question is but here is the problem. Since I'm going for the RAT look I had to move the cab and engine back about 9". By doing that it exposed the steering box to the max. That steering box has to go and be replaced by a rack & pinion set up. The new rack and pinion will have plenty of room right behind the radiator shell and in front of the cross member. Not a problem with mounting the new R&P. Now the problem boils down to bump steer and what's the best R&P to install. Currently I have a Dodge Dakota unit that exagerates the bump steer issue. I'm trying to figure out if I should scrap the Dakota unit or try to shorten the middle section containing the rack and pistons.

De_greaser
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Old 08-03-2017, 08:35 PM
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Here's the problem

The old steering box (reciprocating ball) has to go away! A rack & pinion will resolve the problem.
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Old 08-04-2017, 03:49 AM
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Quote:
Originally Posted by de_greaser View Post
The old steering box (reciprocating ball) has to go away! A rack & pinion will resolve the problem.
I'll play the devil's advocate here and ask why? The recirc ball box WORKS... This is a rat rod and the rack goes not "resolve" anything... In fact, it throws more issues, money and time into the mix then just leaving the box alone and moving on.
Leave the box alone, man. It looks fine and you know it works...
Mark

If you want to hide it make a cover to fit between the rails and mount your headlights to it. Trim off the frame horns and bolt a big spreader bar between the rails, right in front of the box.

Last edited by astroracer; 08-04-2017 at 04:18 AM.
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