Will lowering the rack and pinion cause major havoc?

[Cop Magnet]

Hi, guys, thanks in advance for any advice. I am running into a clearance problem mounting a new engine over an Alterktion subframe in my 69 Charger. Most of this can be resolved by dropping the rack about 2" and moving it back a little less than one inch. The subframe manufacturer said this would upset front-end geometry and this could not be altered at all. However, I am not so sure. It seems to me the front-end geometry is unchanged, the only thing changing is a minor angle on the tie-rod ends. Take a look at this pic. I would like to drop the engine another 2-3" (to just above the cross member) and ultimately drop the car 2-3" as well. Yes, I know I need a new oil pan for that :D

83649

[dontlifttoshift]

Simple answer? Yes, lowering the rack 2" will cause major havoc.

Honestly, the rack looks to low already just eyeballing the inner rack pivot against lower control arm bushing......it might be the angle of the picture.

Two things. First, if you don't think rack placement affects front end geometry, I suggest you pick up some reading material and study how suspension works. Chassis Engineering by Herb Adams is a very good start. Second, less than 3" of ground clearance at the crossmember is a bad idea in the Chicago suburbs (the land of permanent road construction).

[Cop Magnet]

Thanks for your input.

[MIKE67]

Lowering and moving the rack forward or back only messes up the bump steer. All the other characteristics stay the same (caster gain, camber gain, offset, anti-dive, Etc). Changing the steering arm could minimize the bump steer if there is room, you have the knowledge or can lay it out, you can safely fabricate or find the correct steering arm and the compromises required are acceptable. You may have to compromise the steering ratio, ackerman ratio or wheel size to make it all work.

The common sketch showing the inner tie rod pivot on a line drawn thru the upper and lower a-arm pivots and the outer tie rod pivot on a line thru the ball joint pivots assumes that both a-arm pivot axis are parallel with the centerline of the car. This isn't always correct. It also assumes that the rack and tie rods are all in-line and perpendicular to the centerline of the car. There are an infinite number of layouts that can have minimal bump steer depending on the actual configuration. It doesn't just have to be as in the common sketch and with the unstated assumptions. That is just one of many solutions. However, finding a good solution with the rack dropped so much is not an easy thing to solve.

It just depends on how motivated/stubborn you are to learn and safely solve the problem.

[Schwartz Performance]

If your tie rod ends are just rod ends then you can make a spacer to make up the difference. Otherwise it's more complicated. Your bump steer will be seriously affected if you lower it 2".
It'd be less severe if you only lowered it an inch, but I'd still look into other alternatives! :)

-Dale

[bret]

Assumming that the original location was truly optimized for steering geometry, moving the rack in any direction by a fraction of an inch will create major steering geometry problems. Hard to explain on paper, even harder to demonstrate in real life.

If you want a no nonsense blue collar way to educate yourself about front suspension and steering geometry, get a piece of pegboard and some yardsticks and work on simulating your set up. With those tools you can easily change the location of the [simulated] components and see firsthand how one change can affect the rest of your system. Finding [and reading some of the more popular suspension therory books along with this exercise will educate you to a level that is beyond many of your peers.

[Cop Magnet]

Motivated and stubborn I am! Thanks very much for your input. We'll make this work one way or another.

[MonzaRacer]

Also if you get tie rods pointing forward or backward from centerline of rack it will REALLY screw up how the toe out on turns functions.
When I swapped in a Gbody/S10 spindle into my Monza it moves the outer tie rods forward, away from the static, straight ahead sitting position.
See when your sitting with wheels straight ahead, the tie rods, steering arms need to be all in nearly straight line from left to right, now position the outer tie rod back from that line or forwards and you REALLY make a mess of angles. You can even cause a car to develop toe out or toe in (depending on front steer or rear steer) going down the road. Also it will side load inside the rack and possibly cause severe wear.
Run a line from steering arm to steering arm, you need to keep in THAT plane with wheels straight ahead.
In theory you should have inner tie rods pivot at same point as control arms, this in theory would eliminate most bump steer. Also in this set up you should try to make steering arm run parallel to lower control arm as much as possible.
In theory your outer tie rod and lower ball joint should run in same angles, lower control arm pivot and inner tie rod the same.
Only time there is change is in a turn.
Now also in all these wonderful angles is the fact you must miss chassis, sway bars, engines, and you also MUST have toe out on turns so the car can TURN.
Bump steer you check in straight ahead position, preferably on live alignment machine, BUT you can do it with plumb bobs, tape measures, masking tape, etc. Also properly set up you need to research making cheap turn table from an alignment rack. OR buy them.
This allows suspension to function (if you do it with no springs in place, air ride would make measurement much easier but not everyone wants to run it).
IF I remember correctly the TruTurn from Ridetech has the Camaro (again if memory serves) to like 0.050"(a dime is 0.033" respectively) or less with no other parts and the rest could probably be tuned out if need be. and 0.050" from bolt on parts in my book as an alignment tech is AWESOME place to start.
And YES I have massaged parts to FIX bumpsteer issues.
My Monza has tie rods pointing partially forward as the steering arms ar longer than Monza, but the increase in wheel AND brake options make it something I am working on. So far I am working on a plate to move my steering box and idler arm forward.
Also dont forget static height WILL change these angles. It is a maddening adjusting process, I had a guy who was dirt racing, and while he never got it I went for low bumpsteer change but we used toe out ot get it too turn FASTER. His car was a mix of parts but the guy had a box full of tapered reamers and would weld up and re-ream to move tie rods in and out to fix issues. He had three sets of center link/tie rods/steering arms, YES we played the arms too.
BUT Igot a HUGE wheel base car to turn inside on small tracks against GM A bodies AND the tweaked Ford Torino chassis cars.
His car was slower in power at first but his skills driving helped him and as we built up his driveline we also broke the bank. Some guys had 2.41, 2.55, 2.73. 2.93 geared rearends, and ran in 2nd.
He had three rear ends and ran in high gear, he never broke a TH350 with manual VB and we also figured out how to use lock up converters to his advantage, the converters just didnt last long. BUT the hole shots off the line AND locking up to pass made his tricks work better.
No one ever got the idea from his carb mounted kick down(stock GM part) instead of kicking it down locked the converter!
Anyway, good luck and hopefully you dont screw up like some I have seen.

[Carl @ Chassisworks]

The subframe manufacturer said this would upset front-end geometry and this could not be altered at all. However, I am not so sure.

The manufacturer/designer of any given suspension is going to be best equipped to answer your questions 99.9% of the time as they are the expert in the room (http://www.cachassisworks.com/whitepapers/001-ExpertAdvice.pdf). This is one of those times. As Bret said, small changes in rack location (we're talking 0.030" changes) will have a significant affect on steering geometry. Not just bump-steer but also ackerman.

That said, I want to raise another question. Why do you need to get the engine two inches lower? Will the hood not close or are you trying to get the transmission to fit in the tunnel at the correct angle?

Looking at the picture you posted above it appears that the rear sump on your pan is already relatively close to the ground. As the rest of the car is out of frame, I don't know if it's mocked up at ride height or full compression. If it is at ride height, then I would be concerned about the pan hitting the ground under full compression.

[astroracer]

Just to add some reinforcement to all of the excellent info you are getting here... Like your subframe manufacturer said, moving the rack WILL cause havoc. They probably said "steering" geometry though, not suspension geometry.
The other issue I see with lowering the rack (besides all of the negative steering geometry issues) is, with a two inch lowering, the rack will become the lowest point on the chassis. You do not want that either. With no protection the rack will be in a dangerous position.
In looking at your photo I see you can lower the engine another inch or so before it contacts the rack. You can run the pan as close to the rack as you need to, just check engine roll or run a solid mount on one side. If you plan to build a new pan anyway the option is there to tuck the pan up closer to the crank in the rack area. Maybe build a dry sump pan? Just some other things to think about.
Mark

[Cop Magnet]

Thanks for all the excellent advice!

I am trying to get the engine lower for an optimal CG and better handling. The hood barely closes and the rear sump is about 3" off the ground now. The crossmember, however, is about 8" off the ground. So I think I have room to move the car down. The rear sump pan will be gone, and I will have a center sump pan made that keeps the lowest part of the pan in line with the front wheels (for some protection on bumps), so it will drop just behind the rack and make up lost volume in width. That will gain me additional room to drop the engine. I actually did talk to Bill Dailey about a dry sump, but it does not raise the front part of the oil pan at all (and it costs $5k just for the pan and pump).

So the limiting factor right now is not the height of the car or the depth of the pan, its the distance between the front of the oil pan and the rack. I hope that explains my logic at least in why I am trying to achieve what I am trying to achieve.

Getting back to the rack, I am interested in swapping it out for a power rack. I talked to Flaming River as it looked like some of their billet racks were narrower in the center, and that might gain me a fraction of an inch without changing the angle on the tie rods. They tell me the power racks are all the same width in the center. So I am back to square one, especially if the rack can't be moved.

Here's another picture for those who don't believe the height of the car! The front end is carrying the weight of the engine and trans here. The coilovers have 500# springs, FYI, and in this pic are adjusted to the center of travel. Thanks again for any input.

83771

[astroracer]

If the hood closes now, dropping the engine another inch will definitly help with that. The center tube on your rack looks pretty small right now. Can you take the rack apart to see if you could "notch" the center tube for a bit more drop on the engine? I would also make sure you aren't going to create header to sub frame/steering shaft/suspension clearance problems by dropping it too far.

[Carl @ Chassisworks]

In my personal opinion, if your hood closes then the engine is where it belongs. All of the extra work to get the CG marginally lower is not going to have a significant effect on the handling of the car. However, modifications required will have a negative effect on the overall design of the suspension. A power rack is going to be larger in diameter than the existing manual rack which will exacerbate the clearance issue.

Multiple people, who know what they are talking about, have advised you to leave the rack where it is. That is my advice also. It's much easier to overdrive a car with bad balance than bad geometry.

From your latest picture, it looks like the engine could go back slightly which would give you some more hood clearance. If you want to significantly improve the balance of the car, cut out the firewall and shove the engine back 6-8 inches.

[Cop Magnet]

Thanks, Carl,
I am not arguing with the people who say to leave the rack where it is. I am acknowledging their input and trying to find other ways to achieve more clearance. My plan to find a rack with a smaller OD (in the same location) is one such attempt. However I am committed to power steering in this heavy car with big front tires that will be used for road racing. Every change affects something else, and I am aware of this issue here, too. Also, I have already cut into the firewall to achieve the current location.
Really appreciate all the input. Regardless of what I do, it will be a culmination of the input of everyone, my own research, and maybe some original ideas.
Thanks!

[Marcus SC&C]

Not to beat a dead horse but... what they said. As Donny mentioned, from that pic it looks like the rack is already too low to minimize bump steer. I think the power rack is a great idea but read up (not in magazines, in real books) on bump steer before you buy one and start chopping. You`ll be glad you did. :)

[Ron Sutton]

Not to beat a dead horse but... what they said. As Donny mentioned, from that pic it looks like the rack is already too low to minimize bump steer. I think the power rack is a great idea but read up (not in magazines, in real books) on bump steer before you buy one and start chopping. You`ll be glad you did. :)

Marcus,
Would you expand on your thoughts & recommendations for him? I think we'd all learn from your experience here. :twothumbs

[mitch_04]

Marcus, I didn't know you were on here. I've read your book, the first one I picked up when I started into the pro-touring world. Good stuff.

Back on topic now....

[Cop Magnet]

Many thanks again to the expertise offered here. Several people now have commented that the rack looks too low to begin with, with the tie rods already at an angle upward. Here is a picture of the front end as installed per the manufacturer specs. As you can see, the tie rod ends are already at an upward angle (compare to the lower control arm) while the suspension is completely unloaded. That angle would only get worse as any weight was put on the front end. So is the original design bad, was this installed incorrectly (I didn't do the install but have all the manuals), or is there some other problem?

83825

[astroracer]

It looks to me like the tie rod needs to go under the steering arm. THAT would put it in the right spot. Can I ask what that is UNDER the steering arm, the tall boss that the lower nut is tightened against? Probably part of a bump steer fix kit but, if the tierod is placed under the arm, I don't think you will need it.

[Carl @ Chassisworks]

The tie-rod goes UNDER the steering arm. There is a sleeve welded to the arm as shown below.

http://www.reillymotorsports.com/alterktiontech.shtml
https://static1.pt-content.com/images/noimg.gif

[Bill_Reilly]

First, yes, the tie rod goes on the bottom of the steering arm.
The racks are 80-93 Mustang style. We like AGR racks, but any will physically fit. If you want a cheap tester just grab one from the local napa store to do all your fitting. But I wouldn't use it permanently, they kinda suck. The tie rod sleeves and mounting bolts/bushings you have now will interchange with the power racks, but the steering ujoint is a different size.

Lowering the engine below the current rack position wont gain much of anything as you wont be able to change the cg height enough to make a difference, but will create a mountain of suspension work that only results in a mediocre steering geometry and zero gain on a track.

The best route is to notch a Viper pan in the front so it's just below a tube-style pickup, then mount the engine with about 1/2" of clearance to the rack. This is by far the cheapest and nicest solution, with lots of ground clearance, but the engine still clears the factory wiper motor. Another good tip is to use the viper "shorty headers", just the cut 90's off the bottom, rotate them so they aim out the back and weld them back on. Custom headers also work great but the shorty mod is mountains cheaper for any stock HP V10.

You can also just barely fit it into a stock engine compartment if you make your own thermostat housing to take up less room. It does move some weight forward, but if you move the engine back, make sure you plan for a gas pedal location before you weld up the new tunnel - and carpet adds another 1/2" to the floor.

On ride height, measure the shock from mounting bolt to mounting bolt. My favorite ride height is 11.5". Its low enough to look right, but has a good ride quality and plenty of room for 3" exhaust under the floor pans. Keep in mind that standard underpinnings will hang down almost 4" below the floor pans under the car, and if you drive the car with any sort of gusto, you need a couple inches of clearance.

Here are a few photos, the V10 installed with the car pan and a couple correct ride height pictures so you can see what you're shooting for. All of these cars have a front shock length of 11.5" at ride height with tires about 25.5" dia.

And finally, since I don't know the history, I'd guess that system is 6 or 7 years old based on the picture, you should look at any rubber parts to make sure they're in good shape from sitting so long. Some cheaper rubber bushings tend to dry out and crack over time. I ran into that with some types of rack mounting bushings in the past.

838328383583834838338383783836

[Cop Magnet]

You are absolutely correct, from the first reply on down! Thanks again everyone.

[Cop Magnet]

Bill, thanks for your response. I plan on something similar with the rear-sump pan, which will convert to a center sump and we will bring the front of the pan up as well. Call me or email me and I will buy the power rack from you. You have my info.

And yes, the receipts say 2009 on the Alterktion.