Front suspension idea
- Thread starter R.O.B.
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Wheelbase should affect ackerman angle. From what I've read, ackerman angle is measured from the pivot point through the steering point, towards the rear axle. Optimum point being dead center of the axle. Well, if the wheelbase changes, that will make the optimum point be perfect, or not even close. Right? 7-8" seems like that would make a big difference.
Ackermann Angle
The only way that the wheelbase would change is if the position of the center of the spindle changed.
If you are just replacing parts, it's likely that you would want to keep the spindle in the same exact place, in order to position it in the center of the wheelwell, right?
So . . . if you do that, then the wheelbase at that point would be the same.
By the way . . . if you DON'T position the center of the spindle in the center of the wheelwell, you will have a lot more problems to worry about than ackermann angle!
( ;-{)}
Please keep us up to date on the status of your e-mail to AJE regarding the purchase of just the K-member (or, if we're smart, the tubular lower control arms, too--since they were made for that K-member!).
The only way that the wheelbase would change is if the position of the center of the spindle changed.
If you are just replacing parts, it's likely that you would want to keep the spindle in the same exact place, in order to position it in the center of the wheelwell, right?
So . . . if you do that, then the wheelbase at that point would be the same.
By the way . . . if you DON'T position the center of the spindle in the center of the wheelwell, you will have a lot more problems to worry about than ackermann angle!
( ;-{)}
Please keep us up to date on the status of your e-mail to AJE regarding the purchase of just the K-member (or, if we're smart, the tubular lower control arms, too--since they were made for that K-member!).
I was reffering to wheelbase change as in my 1967 Mustang has a 108" wheelbase, and I'm talking about using SN95 spindles, which a SN95 Mustang has a 101.3" wheelbase.
Right . . . well, let's talk a little bit about the ackerman angle for a minute . . .
Basically, it is an angle where the outer wheel has a larger turn radius than the innter wheel.
So, that means that the inner wheel must turn inward more than the outer wheel.
The components that dictate that are the steering gear, the attaching hardware, and the length of the steering arms on the spindle (to a somewhat smaller degree, the angle of the steering arms as well).
If the spindle itself is centered in the wheelwell, and the steering arms themselves are the exact same length as the ones on the old spindles, there would be no changes whatsoever, assuming that the same steering gearbox and attaching hardware were used.
This wikipedia page should show how those are the component that actally affect the angle:
Ackermann steering geometry - Wikipedia, the free encyclopedia
Hope that makes sense . . .
stonecoldtx, your link show exactly what I'm referring to. The first picture shows the steering arm angle going towards the center of the rear axle. If that axle were to move, ie.. longer or shorter wheelbase, then the angle will still be pointing to that old spot, therefore, ankermann angle will have changed.
Also, I got a reply back from AJE Racing: Our K-member is only built to accept our a-arms or a custom built piece. We do sell everything seperately.
Also, I got a reply back from AJE Racing: Our K-member is only built to accept our a-arms or a custom built piece. We do sell everything seperately.
So . . . they indicated we could purchase just the K-member and their control arms separately? If so, we could use the SN95 adapter and use those spindles.
Regarding the ackerman angle . . . again, if you place the spindle in exactly the same location (center of the wheelwell), there will be no difference in wheelbase.
Also, again, the components that control the ackerman angle besides the wheelbase are these items:
1.) Steering gearbox, which controls the amount of travel available to manipulate the steering arms of the spindles
2.) Hardware attached to the steering gearbox, because altering the length would ultimately alter much of the steering geometry
3.) Length of the steering arms attached to the spindles--this is the most important thing. If those arms are the same length as what you are replacing, AND you have placed the spindles in the center of the wheelwell (where they were before), the ackerman angle will remain the same.
Why? Simple--if the ackerman angle is affected by the wheelbase (which it is, but it's not the *only* factor), and you haven't altered that (by placing the spindle in the center of the wheelwell), then the only other components that would affect it would be the items I have listed above.
If you look closely at the diagram, it shows that, when in a turn (which is when the ackerman angle comes into play), the third point of the triangle is *not* at the centerline of the rear axle--it is at the centerline of the turning radius.
Hope that clarifies that changing to a different spindle won't affect the ackerman angle so long as:
1.) The spindle is located in the center of the wheelwell (which maintains the same wheelbase)
2.) The steering arms on the spindle are the same length as the ones being replaced, and
3.) None of the other components have been changed (i.e.: steering gearbox, linkage, etc.).
you're really comparing apples to watermelons here snice the early mustangs paralellogram steering system will have way more ackermann than the SN-95 or any other rack and pinion system anyway. and just because you swap a spindle from one car to another doesn't mean you're going to run into ackermann issues any way. for instance a 69 mustang, 69 cougar and 69 torino coupe/sedan and 69 torino wagon/ranchero all have different wheelbases and all use the same spindle. it's the same for fox body cars too, mustang/capri, fairmont/LTD II and t-bird/cougar also have different wheelbases and they too all use the same spindle.
don't worry so much about wheelbase when you calculate the ackermann, the main thing you need to be concerned with is track width and that can vary some between shared platforms as well
I did some more reading up on the Ackermann angles today, specifically reverse Ackermann. I came to the conclusion that in everyday passenger cars, perfect Ackermann is preferred. But for a race driven car (like the way I drive), going with no to reverse will actually help traction due to the way the tires grip and slide in high speed, heavy load curves.
So yea, I'm not worried about this Ackermann angle anymore. But thank you all for the input.
So yea, I'm not worried about this Ackermann angle anymore. But thank you all for the input.
I'm going for it!
OK, so I contacted AJE Racing, and found that they would sell the K-member, the lower control arms (with ball joints) and the rack kit separately from the full kit.
They priced it to me for $1278!! That's an AMAZING price! That's less than just about any rack conversion kit on the market except Steeroids!!
AND--it's a full K-member that holds the motor mounts, *not* just the crossmember! You can eliminate the strut rods in the front, and I think they said the stock sway bar bolts right up to the lower control arms in the stock location.
The only major drawback is that because it changes from a "rear steer" configuration to a "front steer" (using a stock Fox-body rack), you have to use a rear-sump oil pan, and unless you have a roller block, you might have to rig up a dipstick; however, if you get an aftermarket pan, like a Milodon or a Canton, it might have a provision in the pan for a dipstick (I already have a roller block, and the 393 I'm building is also a roller block, so I've got dipstick provisions already).
OK, so the next obstacle is the SN95 spindle; found a couple of them complete with hubs for $90 shipped. Per AJE--the lower control arms are designed for Fox-body spindles, and the only thing required to make SN95 spindles work is to use a 3/8" shim on the top of the balljoint shaft to place the castle nut in the correct location.
Next--I checked into the adapters for the SN95 spindles, and found out that they were engineered to take a Moog K772 ball joint, which is a Chrysler screw-in balljoint.
I did some searching on the web, and it appears that the taper on this balljoint is the same as that for a Pinto; anybody know how that taper compares to the standard ball joint on a classic Mustang?
Also, if the taper is different, is there a balljoint with the correct taper that would work on the upper control arms?
If the taper is different, then hopefully there is a balljoint with the correct taper out there that will work.
Anybody got specifications on balljoints and cross reference books?
OK, so I contacted AJE Racing, and found that they would sell the K-member, the lower control arms (with ball joints) and the rack kit separately from the full kit.
They priced it to me for $1278!! That's an AMAZING price! That's less than just about any rack conversion kit on the market except Steeroids!!
AND--it's a full K-member that holds the motor mounts, *not* just the crossmember! You can eliminate the strut rods in the front, and I think they said the stock sway bar bolts right up to the lower control arms in the stock location.
The only major drawback is that because it changes from a "rear steer" configuration to a "front steer" (using a stock Fox-body rack), you have to use a rear-sump oil pan, and unless you have a roller block, you might have to rig up a dipstick; however, if you get an aftermarket pan, like a Milodon or a Canton, it might have a provision in the pan for a dipstick (I already have a roller block, and the 393 I'm building is also a roller block, so I've got dipstick provisions already).
OK, so the next obstacle is the SN95 spindle; found a couple of them complete with hubs for $90 shipped. Per AJE--the lower control arms are designed for Fox-body spindles, and the only thing required to make SN95 spindles work is to use a 3/8" shim on the top of the balljoint shaft to place the castle nut in the correct location.
Next--I checked into the adapters for the SN95 spindles, and found out that they were engineered to take a Moog K772 ball joint, which is a Chrysler screw-in balljoint.
I did some searching on the web, and it appears that the taper on this balljoint is the same as that for a Pinto; anybody know how that taper compares to the standard ball joint on a classic Mustang?
Also, if the taper is different, is there a balljoint with the correct taper that would work on the upper control arms?
If the taper is different, then hopefully there is a balljoint with the correct taper out there that will work.
Anybody got specifications on balljoints and cross reference books?
From what I looked into, that ball joint will work for the Pinto/Mustang II spindles, classic Mustang spindles (both upper and lower), and lower ball joint for SN95 spindles too. This ball joint is also widely used on stock car racing, so they make alot of upper control arms for dirt cheap. Just need to figure out the correct size to use, and weld in some tabs to allow for the spring perch. Or, you can just keep the stock upper control arm setup, or even go with the above mentioned aftermaket control arms, like TCP for example, because it should bolt up to that adapter, its what I suggested in the first post. But now I'm looking at the stock car catalogs for a cheaper version to work. Anyone got some info?
i have another option for you that might be even cheaper than what you're looking at now.
check Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks and look at their mini-subframe kit for classic stangs. basically it replaces the stock lower control arms and strut rods with a tru A-arm setup and it only runs about $400 or so, the benefit here over the AJE kit is that the lower arms are adjustable so you don't have to rig up some kind of crazy system to adjust the upper arms or have to resort to an adjustable upper arm.
here is the CPP lower A-arm setup
Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks
you won't be able to use a front steer rack with it though, so you'd be back to trying to find steering arms for the SN-95 spindles but you could still use your stock upper arms or the global west arms OR CPP also has their own tubular control arms for another $300 which is about half the price of most other aftermarket arms. add to that a Randalls, Unisteer or Steeroids rack kit and into the whole system for less than the TCP coilover kit.
if you still want the ajustability of coilovers you can use the TCP, Ron Morris, or CPA coilover kit for stock style upper control arms. the CPA coilover kit is the cheapest of the three with TCP being in the middle pricewise.
here is the CPA coilover kit (not to be confused with CPP, different company)
CPA--products
check Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks and look at their mini-subframe kit for classic stangs. basically it replaces the stock lower control arms and strut rods with a tru A-arm setup and it only runs about $400 or so, the benefit here over the AJE kit is that the lower arms are adjustable so you don't have to rig up some kind of crazy system to adjust the upper arms or have to resort to an adjustable upper arm.
here is the CPP lower A-arm setup
Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks
you won't be able to use a front steer rack with it though, so you'd be back to trying to find steering arms for the SN-95 spindles but you could still use your stock upper arms or the global west arms OR CPP also has their own tubular control arms for another $300 which is about half the price of most other aftermarket arms. add to that a Randalls, Unisteer or Steeroids rack kit and into the whole system for less than the TCP coilover kit.
if you still want the ajustability of coilovers you can use the TCP, Ron Morris, or CPA coilover kit for stock style upper control arms. the CPA coilover kit is the cheapest of the three with TCP being in the middle pricewise.
here is the CPA coilover kit (not to be confused with CPP, different company)
CPA--products
bnickel, the downside to this kit is it keep the lower control arms at an angle, just like the factory setup. But with the AJE k-member (or something custom), this relocate the control arms to a straight level angle. So, when combined with the proper location of the upper control arm, you will now have VERY GOOD suspension geometry.
I wander what AJE would sell just the K-member and control arms for? This way, if you chose to still use the stock spindles, you could keep rear steer. Or, like me, I could scrounge up parts for the FOX front rack cheaper. Anyone know the price? or if they will even do it?
AJE K-Member
Well, you could always ask them, but I'm not sure why you would want to keep the stock spindles (the lower balljoint on the control arms is a stock Fox-body balljoint).
It's my understanding that front steer is superior to rear steer, but I'm not clear as to why that is (maybe someone with a better understanding of the differences could illuminate us?).
Regarding buying just the K-member and control arms, and scrounging up the rack parts--I thought about that, but the kit that is included in this price also has the intermediate steering shaft that was designed for use with this rack in a classic Mustang, the rack itself, and the other hardware is already all there . . . the tie rods and ends, a bump steer kit, mounting provisions and hardware, etc.
In my opinion, it's a SMOKIN' good deal for everything you get, when compared to other rack conversion kits out there, AND it's already all engineered to work in a classic Mustang!
Well, you could always ask them, but I'm not sure why you would want to keep the stock spindles (the lower balljoint on the control arms is a stock Fox-body balljoint).
It's my understanding that front steer is superior to rear steer, but I'm not clear as to why that is (maybe someone with a better understanding of the differences could illuminate us?).
Regarding buying just the K-member and control arms, and scrounging up the rack parts--I thought about that, but the kit that is included in this price also has the intermediate steering shaft that was designed for use with this rack in a classic Mustang, the rack itself, and the other hardware is already all there . . . the tie rods and ends, a bump steer kit, mounting provisions and hardware, etc.
In my opinion, it's a SMOKIN' good deal for everything you get, when compared to other rack conversion kits out there, AND it's already all engineered to work in a classic Mustang!
on paper there is no pro/con to either properly engineered. but in the real world where parts bend/flex/etc, a front steer puts the tierods in tension vs compression. the major drawback comes from packaging in the design phase... the steering arm on a front steer must move out vs in on a rear steer to attain proper ack angle.... but using factory designed parts, there is no need to worry about this.
all that said, i am doing something really similar to this on my 64.5, a copied sn-95 k member(basically im just gonna jig the rack & lca monting points, and built the rest to fit the early rails and my uca mounting points) i plan on running fabricated spindles(coleman) and an adjustable upper arm w/ coilovers. i want the extra track width of the sn95 arms, and the rear will be custom width anyway. i just want to run late model offset wheels with no spacers.
I've done something similar to what you guys are talking about. I too really liked the Griggs but the price is a little out of what I wanted to spend. I am putting in a 4.6 4V motor too so I needed to get rid of the towers. I am not crazy about the mustang II setup for what I was wanting. I am using the SN-95 spindle, fox rack, and a custom crossmember and towers. Really, you can make any track width you want. I set mine up a little wide since I am running FR500 wheels made for the SN95. The fox track width is almost exactly the same as the 67-70, but the fox spindles are not as nice. You can use '94-95 spindles which are the same track as the fox, but use the same brakes as the 96-04. If you are doing your own deal, you really need to pay attention to your geometry. I looked at a stock K-member suspension points for the lower and modified from there. I moved the lowers a little and designed a shock tower, upper a-arm, and a-arm adapter. I tried to use a standard round track style a-arm but ended up making the ones on the attachment.
The rack is moved a little bit from the stock sn-95 geometry. Personally, I would not go to strut design like the stock sn95. In my opinion, a strut design would be a step back from a modified stock sla setup.
The rack is moved a little bit from the stock sn-95 geometry. Personally, I would not go to strut design like the stock sn95. In my opinion, a strut design would be a step back from a modified stock sla setup.
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