Ride hight

@Rob Fridenberg posted:

Changing shocks has morphed into a major suspension geometry project!!

Interesting discussion!

Yes but all considered, is worth the discussion. If you are going to mess with the bump steer, when you do the shocks and springs would be a good time to consider it.

What was available 25 or 30 years ago is not necessarily what is available now.

At this moment, it does not appear that Aurora makes that combination of a rod end. If I am understanding this correctly, it's a 5/8" bore and an 1/2"-20 thread. None of the suspension shops I've talked to SO FAR have it or see it as available.

That MAY explain why so many of the "kits" are adapting a male rod end with that double threaded sleeve?

I'm aware that the rack centerline moves forward 3/8" shimming it down 3/8". I saw that up against my battery box and had to clip that corner and switch to a socket head bolt.

It is entirely possible that on a street car this is just an academic exercise in futility but at the moment gives me something to do in laying out the details.

I do not look forward to measuring the bump steer. That ain't fun.

Generally speaking, you do not want bearings or bushings to be substantially on threads. The more load, the more it's not good practice. We go through great lengths, by using AN bolts, to keep everything on the shank, including mounting tabs/brackets and then use spacers/washers then nuts.

Doug, Like almost everything to do with suspensions, there is no one magic minimum bump-steer number. Less is always better. Yes, the ideal is zero but that MIGHT (not likely) be obtainable through a very short part of the range of travel. Anyone that hasn't looked at a bump-steer curve should do so to better understand what's going on.

Furthermore, a number is somewhat meaningless unless the method of measurement is defined. Ideally the steering angle introduced by suspension travel should be kept to a minimum. The condition and compliance of the suspension system can affect the accuracy of the measurements and whether or not the driver can sense some bump-steer. Excessive B-S will be felt.

By nature suspension systems are dynamic and things can change quite a bit through the range of travel. To make things more complicated, what the driver senses can be influenced by many things.

The spring/shock system has nothing to do with suspension geometry other than limiting the travel in both bump and droop. Once you start modifying a suspension system you really need to check everything for max performance. Changing ride height and the wheel/tire package can effectively changes where in the travel range the suspension is operating which will change alignment (as BOSS said) and preferred settings. The good news is that minor changes may not be that significant for a street car with street rubber. An alignment will be necessary, as BOSS said.

The car was designed around a static ride height and specific tire diameters. If you significantly deviate from that thing can change including optimal wheel alignment specs.

Donny, In your case having a popular wheel/tire package is a good start. Next determine the static ride height. As a broad rule of thumb don't go lower than what keeps the effective lower front A-arm parallel to the ground. Important: meaning imaginary line from about mid-point between inner mount to center of the ball joint. If the inner A-arm mounting points are higher than the center of the ball joint, that can be acceptable. If they are lower, then you can have excessive camber gain through upward suspension travel which is generally not good for street cars. Then you have to make some decisions. How low can you live with. How stiff (higher spring rates) a suspension do you want to live with. Is the car for show or go. Aesthetics are important to many people. I think we all like low but banging on the road gets old very quick. Shocks/springs and bump-steer adjustment come next. Enjoy the learning experience.

I have call around including Pegasus,1/2" heim w/ 5/8" bore do not exist, I even tried off road shops. You can only get 1/2" and 1/2" or 5/8" and 5/8" WTF! I guess it's plan B. Steve said in 71 when the first cars were delivered, Ford installed shims on customer cars due to complaints. My car is has all stock steering and I haven't hit any big  bumps or pot holes but, the dips really affect the car. At first I thought this car had a bent A arm or other jacked-up suspension component. After disassembly, cleaning and closely checking everything I'm sure It's the position of the rack. I guess I'll drop the rack and see what that will do not unless somebody knows where to get the right stuff, Hiem joints are the ticket.  

Thanks for the reply. I agree about the rod end on stud threads but the only way you could stay off of the threads would be to use a hardened sleeve over the threads and probably the shims. That capability is not in the design of any of the readily available "ball joint studs".

Again, we don't need to speak in generalities here. We are speaking of the Pantera by folks who have raced the Pantera. Yes on all suspensions as the hub rises and falls, there is a change in toe since the hub center is acting through an ark.

The point here is that since we are talking specifically Pantera, the change without the shims is know (known by someone) and the improvement using the shims is know by someone.

In addition, going through the BossWrench modification, the improvement IF ANY is known by someone.

If an 1/8" change is stock and it can be reduced somewhat with lowering and further improved by the additional BW mod that would be nice to know in advance.

It isn't a criticism of anyone here, I'm just pointing it out that it is under these conditions, no  longer just a generality, the numbers are known.

In my GT350, when I lowered the upper a-arms in what is called the "Shelby modification", the bump steer change was horrendous. The car would hit a bump and change lanes suddenly and harshly. That originally was with bias ply tires though and radials reduced if almost eliminated the jerking steering wheel.

I installed a "bump steer eliminator kit" and there is no felt reaction to the steering wheel now.

I'm going to take a guess here and say that the BW modification is most likely unnecessary on even a hard driven street car, but I don't know that as a fact, but it with be nice to know (translated as: I suppose it would amuse me).

This thread unfortunately has suddenly gone no where fast.

FWIW, I use 1/2" thread by 1/2" bore heims in my steering, along with 1/2" taper/straight studs. No real reason to use a heim-thread that's smaller than the stud its attached with.

The Pantera is built with rather light-appearing front suspension parts. Compare a Pinto front spindle pr steering arms to a Pantera spindle & steering arms, and you may be shocked. Yet average Panteras still survive racing LeMans (Classic), monstrous-oversize engines and 50 yrs of  'vigorous' street driving.

I personally do not use teflon lined joints in areas that are likely to pound out. I've lost a few, which convinced me to avoid them. I use premium all-metal heims. YMMV, as always.

I just measured the stud diameter on the tie rod end to steering arm on my car. It is 10 mm. That would be a 3/8" stud to use then. 1/2" stud would be too big.

Those I can't find at all.

I went ahead and shimmed the rack per Steve's advice. I asked him about putting hiem joints up front and he said, "YOU'VE BEEN ON THAT PANTERA FOURM, HAVEN'T YOU?!?! YOU CAN DO WHAT YOU WANT, BUT THIS IS WHAT I WOULD DO.... Shim the rack a 1/4", no wait, make that 3/8"."  Using 1/8" x 3/4" alum flat bar, I made my shims, grabbed some longer bolts and put it back together. Has anybody ever had one of the rack mount welded backing nuts break loose? They are almost impossible to get out. The rack is dead nuts level when loaded. I will see how it acts tomorrow. BTW, I just took on a young person as a helper to help me on all my projects. She's very eager to learn and not afraid to get dirty.

@Donny Dotson posted:

I went ahead and shimmed the rack per Steve's advice. I asked him about putting hiem joints up front and he said, "YOU'VE BEEN ON THAT PANTERA FOURM, HAVEN'T YOU?!?! YOU CAN DO WHAT YOU WANT, BUT THIS IS WHAT I WOULD DO.... Shim the rack a 1/4", no wait, make that 3/8"."  Using 1/8" x 3/4" alum flat bar, I made my shims, grabbed some longer bolts and put it back together. Has anybody ever had one of the rack mount welded backing nuts break loose? They are almost impossible to get out. The rack is dead nuts level when loaded. I will see how it acts tomorrow. BTW, I just took on a young person as a helper to help me on all my projects. She's very eager to learn and not afraid to get dirty.

No one said that shimming down the rack wasn't going to put you about where you want to be.

In lieu of a detailed text it's really impossible to determine if going to a stud and heim end will give better results. Heims are not what you really want to use on regularly driven street cars. They have no where near the longevity of a stock ball joint or a tie rod end.

They are also know for their harshness.

To me this was just a technical discussion on how to do it but lacks the technical documentation of what the results would be.

That really requires a "text" on the subject and is unfair to expect anyone to write one on just the drop of the hat BUT the thought is out there...somewhere.

I've worked with NASA guys and to be honest, they are a lot pissier then some of the knowledgeable here and probably a good deal more secretive. In the world of ulcers, they are what medical people call "carriers".

P.S.: don't invite any of them to your barbecue. They'll bum everyone out.

The kid needs to hit the gym. He needs some toning.

Good for you for trying stuff, and for bringing the younger people into the world of automotive!

Rocky

I wanted to put hiems on because it was easier and more adjustble but, you can't install what you can't get. Removing the rack and adding shims was a job I just didn't want to do and then one of those backing nuts came loose causing more grief. One good thing came of this, it cost less than 10 bucks to have the same outcome.

Donny, You did the right thing installing shims per Steve's advice. If the adjustment substantially reduces the bump steer that you were experiencing then you are good-to-go, unless you care to measure what you now have and try improving it further with more adjustments by using measurements. You might or might not "feel" additional improvements. A lot depends on what you are comfortable with. If your sense is that the shimming has eliminated bump steer then you found the number that works for you and your car setup.

Sorry for the suspension geometry 101. Apparently that offends some people. It's my nature to thoroughly understand a mechanism before I start modifying it. It's sometimes easy to put the cart before the horse so I share what I know in hopes to be helpful.

BTW, Great to see you found a willing helper. Give him a few years and you will be his helper

Love suspension geometry 101!! There are so many factors involved in tuning the dynamics of a car. Even the wheel design (and tire), which has its own spring rate, can have an effect. On one of my car programs, the wheel design/stiffness needed to be revised to resolve an issue with the suspension tuning. The studio was not happy with us!

The computer has made suspension modeling/analysis so much more precise - I recall we started using it in the mid-Eighties.

Is the bad bump steer common with Panteras or an issue related to Donny's car set-up??

Bump steer is common with cars. The Pantera is unusually adjustable, having come from a racing background. Plus, often having sensitive steering and sensitive owners who care. Removing as much of the stuff that makes you uneasy, increases your enjoyment of the machine, in my opinion.

...Heim Joints?? Are You building a Racecar?

I HAVE Absolutely NO Bump-Steer at speed on the Freeway. And I have Multiple Cockpit Videos to Prove It! No misdirection of the Pantera, No steering wheel Movement, And NO need for a 'Correction' in the Steering, when hitting Severe Bumps, multiple times!

All I did, was to Install after-market shocks (Hall), adjusting the height I wanted, make sure both shocks were set Even (Dial Calipers), test drive to settle the springs, re-check height...After, I installed a Pair of 3/8" Stainless Steel Bar 'Anti-Bump-steer' Spacers under the Rack. I use to Machine these, and a few of You have these in Your Panteras. That's all I needed. Of-course, get a 'front-end alignment'.

I don't get all of the Complications of suggestions going on here? You don't even know yet, if you have bump-steer.

A few points:

Teflon Squeezes Out!

Doug is Right! With a 'Lowered' Battery Box, things get very tight around the Steering Mount Bolts.

The Most Important and 'Delicate' set of bolts in the entire Pantera (rack mounts), and one would put 3 aluminum Shims Under them?? Not Rigid, and prone to slipping and loosening, Not to mention Corrosion. As a Machinist...I say, one would be 'Out of Their Minds'!

You're going to do what you please, but keep it simple. The More complicated you make it, the more Likely the Components will NOT 'Compliment' each other. KISS

Good-Luck with it!

MJ

...had to come back and mention, I had previously installed the TRW Racing Steering Rack, long ago sold by Roland in Germany. It has a 10% Faster Ratio. Works Beautifully, and I don't care about any immeasurable increase in steering effort.

@marlinjack posted:

...Heim Joints?? Are You building a Racecar?

I HAVE Absolutely NO Bump-Steer at speed on the Freeway. And I have Multiple Cockpit Videos to Prove It! No misdirection of the Pantera, No steering wheel Movement, And NO need for a 'Correction' in the Steering, when hitting Severe Bumps, multiple times!

All I did, was to Install after-market shocks (Hall), adjusting the height I wanted, make sure both shocks were set Even (Dial Calipers), test drive to settle the springs, re-check height...After, I installed a Pair of 3/8" Stainless Steel Bar 'Anti-Bump-steer' Spacers under the Rack. I use to Machine these, and a few of You have these in Your Panteras. That's all I needed. Of-course, get a 'front-end alignment'.

I don't get all of the Complications of suggestions going on here? You don't even know yet, if you have bump-steer.

A few points:

Teflon Squeezes Out!

Doug is Right! With a 'Lowered' Battery Box, things get very tight around the Steering Mount Bolts.

The Most Important and 'Delicate' set of bolts in the entire Pantera (rack mounts), and one would put 3 aluminum Shims Under them?? Not Rigid, and prone to slipping and loosening, Not to mention Corrosion. As a Machinist...I say, one would be 'Out of Their Minds'!

You're going to do what you please, but keep it simple. The More complicated you make it, the more Likely the Components will NOT 'Compliment' each other. KISS

Good-Luck with it!

MJ

...had to come back and mention, I had previously installed the TRW Racing Steering Rack, long ago sold by Roland in Germany. It has a 10% Faster Ratio. Works Beautifully, and I don't care about any immeasurable increase in steering effort.

I did the shim installation a few years ago and with this thread I was just under the car checking dimensions, and components, etc.

I recently installed all new poly bushings and flanged 12.6 bolts and locking nuts.

On the rack mounts, I did have to clip the corner against the battery box and change to an Allen socket screw/bolt but I do remember having to remove the battery box in order to access the bolts.

I also noticed that I needed to dimple the sheet metal on the battery box where the rack brackets are. It's one of Hall's stainless steel louvered boxes.

I don't notice any steering wheel jerking on the bumps either but admittedly I HAVE NOT measured toe changes with suspension travel. That is a big project to accomplish and was deemed at the time, unnecessary.

So I'm ok for now without the Heim's and considering that the combination of parts necessary to do the swap over is just not available, that kind of ices the cake at leaving the entire thing alone BUT I still want to do adjustable shocks (double) and springs. My Koni's are still in there.

So maybe the adage of "if it ain't broken, don't fix it" applies here?

I finally took it out for a test drive after doing a temp driveway alignment. The shocks worked great and the car didn't act up going threw dips on the freeway at speed like it use to. I'm realty happy it doesn't squeak like a old pick-up truck,so embarrassing. I don't know if this car is different form other 71 cars but, I had to modify my lower rack mount/ brace. After adding 3/8" shim material I ran out of real estate to drill new holes on the bracket. Here is the pic.   

That's common with bump-steer shimming, Donny. Your mod looks nice. Alternatively, some redrill the frame holes for that rack-brace bracket- which on many '71s was not a factory part. It was actually developed by the West Coast prep shop Ford hired to get the cars ready for dealers, right off the boat. It was originally called the "Bill Stroppe bracket" and Ford picked it up for production. It's worth keeping- some guys leave it off and then have 'funny' steering.

Did you notice took a little bite of the cross brace for cooling pipe clearance and added some strength to the opposite side with a gusset? I just put a new gun on my mig, it really looks like I can weld.  After shimming the rack down 3/8" or so, I wouldn't trust just the four bolts holding it into place, one of the four bolts failed on my car.I think the Bill Stroppe bracket was necessary for some extra piece of mind. That's a interesting bit of info. I further tested my car today after getting an legit alignment, my driveway toe job was off  ten miles but, my camber was very close. The more I drive this car the more I like it. It drives, shifts and brakes pretty dad gum good for a old car. I think I'm done sorting it out, it will idle all day with the A/C on and then start right back up like a normal car. The Pantera is a cool car in my opinion. I'm interested in trading for a project car or two. I like Mopars, early, early  Z 28s, Trans Ams, GTOs , AMXs or ? I'm just throwing it out there. My 70 Hemi Challenger project is almost done so, I need to keep busy. BTW Boss I like the way you explain things so mentally handy-caped people like me can understand, sometimes I'm dumber than a box of rocks and I say such stupid things.         

By stupid things, do you mean

“I’m interested in trading……”

😎✌️

Larry

I do stupid stuff on a daily basis. Sometimes I shoot myself in the foot making trades and sometimes I do OK. I get bored with same stuff, I like new challenges. I'm like a tweeker without the Meth except after ripping something apart I put it back together.

Donny, if you need a new challenge, get into fixing and operating old computers . Some you can get free. Once you get them to run, the second part is to get them to run on the Web. All the big mfgrs routinely drop support, then they actively design new ones so the old ones cannot be used even when 'fixed'. No backward-compatibility. They call this 'creating a market'.

Supposedly, some old Ferrari and other EFI race cars are relatively cheap because they once used proprietary software in their controllers. So unless you get the car, the team computers and their modified software, the cars are static displays even if in running condition.