Forward Steering Rack With Maintaining Rear Steering

[The1TrueOutlaw]

This is more a question of curiosity for those who know the ins and out of steering linkage. I've read tons of things about the aftermarket coilover suspension kits that use Mustang II spindles and steering rack ruining the ackerman angle and making low speed driving unpleasant. Seems like a lot of the blame is put towards the rack travel and switching the steering to the front side of the ball joint. So this got me thinking could you put a rack up front while maintaining rear steering?

My thought is having a rack intended for rear steering up front. Using the stock spindle on the e-body. Then there would be two additional arms. The first would have 3 joints, the first joint connects to the tie rod. The second connects in the center to a fixed location (lets say the frame rail), this one is the only non ball joint, it would rotate but stay parallel to the bottom of the frame rail. The third connects to the second additional arm which connects to the stock steering location on the knuckle. Since there is a pivot point on a fixed location it would require the reversal of direction in the rack, which is why I was thinking a rack intended for rear mount.

The issues I am seeing it resolve is allowing for a longer rack travel while increasing the length of the arm connecting to the knuckle to reduce bump steer. I drew up a quick sketch, hopefully it gets across what I was trying to explain.

Any thoughts on other issues that could arise? Think its even feasible to fit all that in there?

[Brads70]

I think your added arms would make the steering much to fast. Packaging would also be an issue. Bump steer is the relationship ( lengths) of the tie rod assembly to the length of the lower control arm. Not equal length  and following dissimilar arc's The missing link/part needed to correct the horrible bump steer in our beloved E-Bodies would be a custom lower ball joint  that positioned the steering arm in the needed position.  I envision it with a screw in ball joint.  I have been playing around with some old Nascar road race spindles to make them work in our cars. Haven't had time /interest to finish it yet....

[HP2]

Every joint introduces another a potential failure point as well as tolerance stack up that will lead to increased bump measurements and greater toe variation. Plus, I'm not sure the frame in the area is flat, so you are creating additional planes of operation which can introduce geometric variation through range of motion.

Front steer can have reasonable ackerman depending on where it links the rack ends with the steering arms. For front steer, this joint must  be inside the wheel hoop, which is why simply reversing the stock steering arm creates negative ackerman.

Even negative ackerman isn't necessarily bad. Some competition cars use it to reduce slip angles at speed and the resulting heat that goes into the tires generated by the reduced slip angle. However, they are willing to sacrifice this for the lack of low speed angles.

It all depends on what are trying to fix based on your intended usage.

[The1TrueOutlaw]

I think your added arms would make the steering much to fast. Packaging would also be an issue. Bump steer is the relationship ( lengths) of the tie rod assembly to the length of the lower control arm. Not equal length  and following dissimilar arc's The missing link/part needed to correct the horrible bump steer in our beloved E-Bodies would be a custom lower ball joint  that positioned the steering arm in the needed position.  I envision it with a screw in ball joint.  I have been playing around with some old Nascar road race spindles to make them work in our cars. Haven't had time /interest to finish it yet....

I appreciate you guys entertaining my crazy idea. In terms or steering speed, I think that would be dependent on the whether the joint connected to the frame would be centered on that arm, I do think that since its following an arc path it may cause some inconsistency in steering speed.

I'm very interested in how the ball joint change would fix the bump steer issue. Is it an attempt to match the angle of the lower control arm and tie rod to stay parallel as they move? If so could you make a new lower ball joint mount that drops the location of the ball joint but maintains the location of the tie rod attachment? I would assume there may need to be an adjustment to the length of the lower control arm as well. Just thinking it may be easier to get a set of lower control arms and ball joint mounts made rather than getting specific use ball joints made.

Every joint introduces another a potential failure point as well as tolerance stack up that will lead to increased bump measurements and greater toe variation. Plus, I'm not sure the frame in the area is flat, so you are creating additional planes of operation which can introduce geometric variation through range of motion.

Front steer can have reasonable ackerman depending on where it links the rack ends with the steering arms. For front steer, this joint must  be inside the wheel hoop, which is why simply reversing the stock steering arm creates negative ackerman.

Even negative ackerman isn't necessarily bad. Some competition cars use it to reduce slip angles at speed and the resulting heat that goes into the tires generated by the reduced slip angle. However, they are willing to sacrifice this for the lack of low speed angles.

It all depends on what are trying to fix based on your intended usage.

I agree that there are a lot of joints in there, potentially too many to be a practical solution. A high level of stiffness would certainly be difficult to maintain.

I am planning for my car to be strictly for street use so negative ackerman would not be good. But that's interesting it can be use for an advantage, I hadn't heard that before.

[Brads70]

I have a buddy that races circle track with a Mopar. He is limited by rules ( pesky things rules! LOL) so he heats up the steering arms and moves them down and in towards the wheel to try and improve the bump steer. " Bent in competition" covers a multitude of sins!     That's why I figure someone making a lower steering arm that accepts a screw in ball joint would be the easiest/best solution.  I wasn't about to heat up the steering arms on a street driven vehicle ( not safe IMO)  so I used Howe quick bump kit.  Worked out really well for me.
https://howeracing.com/index.php/store/steering/howe-quick-bump-tie-rod-ends.html


Here is more details on what I did, A-Body LCA, B-Body center link, C-Body spindles etc....

https://forum.e-bodies.org/wheels-tires-brakes-suspension-and-steering/12/-using-c-body-spindles-on-an-e-body-and-a-body-lcas-and-viper-calipers/58/

I found it to be a night and day difference in handling......

[The1TrueOutlaw]

Yeah, I'm not sure I'd have the courage to heat and bend to fix the issue.

I had to read through your write up a couple times to take everything in. The work you did and the detail in the write up are both imressive. From what I understand the howe quick bump kit lowers the ball joint location to mitigate some of the bumpsteer issues?

I'm not sure if this warrants a whole new thread or not but I've actually been bouncing another thought around and figured you may be interested in commenting on its feasibility. What started it is that I've been trying to find wheels that have a more modern styling without the inset from the face of the rim. Everything I'm finding for a 5x4.5 bolt pattern that fits the bill has about a 40 mm offset where I'm needing something around 0 mm. I could correct that with a bolt on wheel adapter but I dont love the idea of that.

Most modern cars have a wheel hub that bolts to the steering knuckle and a rotor that sits on top of that as opposed to the hub rotor on spindle design our cars have. So my thought was to take a stock spindle, cut off the actual spindle part and machine a plate that bolts to the face of the spindle and bolt a modern hub to the plate. In doing so I can set the plate to add the extra 40mm to bring the wheel with the larger offset back to the correct location and not need an adapter.  I was also thinking this may allow the install of a tie rod location further into the wheel making a front rack possible since everything moves out almost 2 inches.

Sent from my SM-G950U1 using Tapatalk

[Brads70]

In a nutshell, all the Howe quick bump kit does , is it allows the tierod assembly length to be closer/same as the lower control arm  allowing it to travel in the same arc as the lower thus reducing bumpsteer. It's a relatively quick/cheap way to improve bumpsteer using stock parts. You could do the same thing using a rod end and tierods pins but I didn't want to use rod ends.   Beware of people trying to sell you parts that claim to give you zero bumpsteer. They are lying. LOL
Just found another company that also makes custom tierods
https://www.emfrodends.com/collections/emf-tie-rod-ends

I can't see the stock spindles having enough material in them to do what you want , safely. 
Have a look here the GM guys have lots of options. What your describing sounds like later model Corvette spindles. The steering arm is 1 short and 2 tucked into the rim requiring 17-18+ rims
http://baer.com/1968-1974-X-Body-Front-Brakes-Nova-Apollo-Ventura-Omega/
It's not just a spindle, the upper and lower control arms and their mounting points all have to be taken into consideration to get the geometry right. As well as the position of the rack.

[GoodysGotaCuda]

Y-axis placement of the rack will also affect ackermann. You can certainly create perfectly fine steering geometry with a rear mounted rack if you have a blank slate [not reusing knuckles].

The reliability of all of the joints shown on safety critical components would be quite a bit of concern. They all also add additional wear points and compliance to the system, the lack of compliance is partially what makes a rack-and-pinoin sought-after.

People hold rack-and-pinion steering and coilovers up on a pedestal on these old cars, my borgeson box is quite good and not nearly the headache rack's post. Coilovers are only as good as the geometry changes and who is tuning them...and even more importantly whom is driving on them.

I've yet to see any aftermarket K supplier talk about how they have adjusted the geometry of the suspension to improve it. Via ackermann, roll center migration, roll center height, KPI, camber curve, etc...they all just "sell" "tubular" stuff like it's magically better and how it's what you "need".

[1 Wild R/T]

Y-axis placement of the rack will also affect ackermann. You can certainly create perfectly fine steering geometry with a rear mounted rack if you have a blank slate [not reusing knuckles].

The reliability of all of the joints shown on safety critical components would be quite a bit of concern. They all also add additional wear points and compliance to the system, the lack of compliance is partially what makes a rack-and-pinoin sought-after.

People hold rack-and-pinion steering and coilovers up on a pedestal on these old cars, my borgeson box is quite good and not nearly the headache rack's post. Coilovers are only as good as the geometry changes and who is tuning them...and even more importantly whom is driving on them.

I've yet to see any aftermarket K supplier talk about how they have adjusted the geometry of the suspension to improve it. Via ackermann, roll center migration, roll center height, KPI, camber curve, etc...they all just "sell" "tubular" stuff like it's magically better and how it's what you "need".

     Mike gets it...  Change without improvement is either just change or your going backwards...  The original design of our old Mopar's is pretty sound, with a few changes they can handle & ride pretty well....

I haven't read the whole thread but the initial premise of forward mounting a rack & using the rear steer design would definitely be going backwards... The whole point of a rack is to eliminate steering linkage, keeping the original linkage & adding a couple bell cranks would definitely not be better....

[Chryco Psycho]

 

[HP2]

There are various aftermarket brake kits that will increase you track width,but only by fractions of an inch. Many of these kits also use separate hub and rotor assemblies as well.

If you want a significantly wider track width, you could go with longer upper and lower control arms. The issue with this is no one is just knocking out various lengths of control arms so you would be paying for custom fabrication of these, so probably not cheap. You could maybe try talking QA1 into making you a couple inches longer and maybe talk them into selling them as "improved scrub radius" arms that allow more positive offset wheels to be used, but in all honesty, not many prefer that look, so demand may be low.

You'll also need longer tie rod sleeves to match, but that's as easy as buying swedged tubes to match stock rod end threads.

Also, to find the offsets you want, you'll need to look at metric bolt patterns: 114.3. This may open up some different options for selection.

[The1TrueOutlaw]

It would be similar to "Vehicle with Detroit Speed Sub-frame". I was thinking of using the stock lower ball joint and upper ball joint, it would just be a change to the rotor mount. If it makes a difference for strength I was thinking of using the drum spindle and the plate would bolt though all four hole locations. I wasn't thinking the strength would be an issue as the wheel hubs are typically held on with just 3 bolts with much tighter spacing which would have the moment putting a much higher tension force on them. But they are most likely a much stronger grade of steel then the spindle so I'm not sure how confident I can be in the thought.

I was planning to us 17" rims but I was hoping to keep the option of 15" if I decided 17" was too large at some point. This idea was mainly driven by the lack of wheel options for our offset in the style I'm looking for (something similar to these https://racelinewheels.com/142b). I'm sure there aren't too many people that would be looking to add wheels like I want so approaching a company to produce parts may not be appetizing to them. I would prefer to stay away from modifying control arms and machining new knuckles as that brings in a much larger cost for time and money.

Unfortunately the track width needs to increase over an inch and a half on either side, the aftermarket brake kits wont quite cut it.  I've looked through every wheel I can find listed as both 5x4.5 and 5x114.3 the vast majority live in the 40mm offset range. The only other options I've happened on are wheel adapters or going to a company that does custom offsets on their wheels but then you're talking $1500+ per wheel...

I do agree there is much more to steering and suspension geometry than what I've been asking. I was just trying to determine the feasibility of it and if its worth digging deeper into the idea. Changing the suspension just for change is a silly approach and I plan to stay as close to stock as possible (hotchkis TVS, larger torsion bars, etc.). I plan on this car being something I can reliably drive for long hours across the country. From what I've read on keeping the stock steering location it either requires keeping the car with manual steering or putting in a rebuilt/upgraded power steering box. I would much prefer to keep the car with power steering given I want this to be a driver. What I've seen of reviews for the rebuilt/upgraded power steering boxes are great when they work.... and when they work can be pretty spotty. I really want a focus on reliability so I'm a bit leery of going that route. So my thought has been moving toward a rack since there aren't great options (unless I've missed something). The problem there is from what I've been reading there is basically no option for mounting it rearward. In the end I'm not set on using a rack and I will most likely stick with some from of the stock steering system as putting in a rack is looking difficult, time consuming and most likely a set in the wrong direction.

[HP2]

I suggested QA1 as they already make a tubular upper and lower. To add an inch and a half might not be a huge deviation for them and could possible be added to their product line. Otherwise you would be dealing with local fabrication houses. If you go that route, these most likely should be those that already build race chassis and know how to maintain geometry with modified pieces.  There are a couple logical arguments for what you suggest - longer arms create less radial angle changes in minor travel and the added width changes scrub radius and reduces squirm. It also adds to available wheel selection, but to maintain 4 wheel rotation, a corresponding increase in rear track width is also required, which is possible with a different housing, but again, somewhat un-popular in the resulting look. If pursuing this isn't in your comfort zone, this tends to lead you towards either a) bolt on billet wheel spacers, or b) customer or three piece rims that can be made to custom offsets. Either comes with pros and cons. I've actually seen several cars with spacers being used to allow inexpensive modern wheels to be utilized.

Firm Feel and Steer and Gear are rock solid OEM style power units. I've rarely heard of people having issues with these installs working properly. The Borgeson boxes had some issues earlier in the run with mounting, angles, and adapters. Many of these issues have since been resolved and it is a product proving to be the next logical step in improving steering response and feel without using a rack. In all honesty, I'd go with any of these before even considering a rear mount R&P. Replacing the steering box with R&P in the stock locations opens up so many compromises it isn't funny. This is why any place that has decided to use a R&P has ended up going front mount and with an entirely redesigned suspension.

Cost in actual dollars or time is what happens when things began to deviate from OEM. You have asked about some pretty far from stock ideas in this thread. Nothing is impossible until you begin to overlay the cost, time, and effort it takes to create it. That can then change the picture. Some of what you want already exists, some of it doesn't.  You can decide what fits your goals for performance, budget, and time and pursue it accordingly. Just remember that everything effects everything and even a slight change can cause un-intended adjustments in places  you never considered.

[Brads70]

For circle track cars I've been involved with to increase the track width we use later b-body lower control arms.  I can't remember the dimensions off hand I do have some in the garage but they are buried at the moment and I can't easily access them.   I believe you can simply install e-body pins in them.
Nascar used C-Body lowers they are wider but allow for bigger torsion bars as well.

[Brads70]

Vintage NASCAR suspension...