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Invincibleextremes

Ford Super 8.8 irs swap thread. Rear brakes too

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Posted (edited)
3 hours ago, mtnickel said:

True enough. Going to all the work, may as well gain all the other benefits for not much more. 

 

So the ackerman is the same too? Interesting considering the different wheel base. Steering ratio not changed either (ie steering arm is same length?)

The wheel base is the same, both front and rear, and side to side, so I'm not quite sure as to what you are asking.  The reason my wheels stick out so much is that they are wide...

 

You could stay with 17x8 inch wheels and stay withen stock fenders, I just chose not to.  I've always wanted a widebody Z, and built it with 11 inch wide wheels.

 

So the scrub radius, and the Ackerman remain the same as a 240z at factory ride height, unless you choose to change it with really wide wheels, but that is no different than a stock 240z on fat wheels.

Edited by Invincibleextremes

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3 minutes ago, Invincibleextremes said:

The wheel base is the same, both front and rear, and side to side, so I'm not quite sure as to what you are asking.  The reason my wheels stick out so much is that they are wide...

 

You could stay with 17x8 inch wheels and stay withen stock fenders, I just chose not to.  I've always wanted a widebody Z, and built it with 11 inch wide wheels.

 

So the scrub radius, and the Ackerman remain the same as a 240z at factory ride height, unless you choose to change it with really wide wheels, but that is no different than a stock 240z on fat wheels.

I wasn't talking about track width.

The mustang has a wheel base (distance from front wheels to back) of 107.1"

The 240z has a wheelbase of 90.7".

The ackerman usually changes depending on the wheelbase. It might be a little off...but perhaps won't be an issue for most driving situations, but could cause an increase in scrubbing in low speed parking lot maneuvers and tighter low speed corners.

ackerman.jpg

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Ah, I failed to remember that track width has also decreased, so if the track width and wheelbase descrease at close to the same amount, then the ackerman probably is pretty close. My bad. But good food for thought!

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3 minutes ago, mtnickel said:

I wasn't talking about track width.

The mustang has a wheel base (distance from front wheels to back) of 107.1"

The 240z has a wheelbase of 90.7".

The ackerman usually changes depending on the wheelbase. It might be a little off...but perhaps won't be an issue for most driving situations, but could cause an increase in scrubbing in low speed parking lot maneuvers and tighter low speed corners.

ackerman.jpg

Reason the Ackerman remains the same is that the mustang spindles have the same ball joint to tie rod distance as the 240z...  But the tie rod is outboard by a little bit, so using a rack with a wider pivot center Like the wrx then brings this back to stock 240z geometry.

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2 minutes ago, Invincibleextremes said:

Reason the Ackerman remains the same is that the mustang spindles have the same ball joint to tie rod distance as the 240z...  But the tie rod is outboard by a little bit, so using a rack with a wider pivot center Like the wrx then brings this back to stock 240z geometry.

I was under the impression ackerman is based not on the distance from ball joint to tie rod, but rather the angle between the spindle (wheel axis) and steering arm.

Additionally, to correct bump steering it's the inner pivot (ie inner control arm mount point) that has to match the inner tie rod joint. The outboard tie rod mount will mainly dictate how long of a tie rod you need.

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1 minute ago, mtnickel said:

I was under the impression ackerman is based not on the distance from ball joint to tie rod, but rather the angle between the spindle (wheel axis) and steering arm.

Additionally, to correct bump steering it's the inner pivot (ie inner control arm mount point) that has to match the inner tie rod joint. The outboard tie rod mount will mainly dictate how long of a tie rod you need.

That's what I'm trying to say.  The 240z rack has an inner tie rod pivot width of 610mm and the wrx is 650mm. Therefore using s80 Volvo inners and 240z techno toy outers will bring the OUTER tie rod width to where you need them, but it's the inner tie rod distance being increased that will bring the angles back to very close to stock.

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1 hour ago, mtnickel said:

makes sense. 

These are, I believe, the different ways Ackerman changes. But as I said before, since wheelbase and track width are both decreasing, then Ackerman is Probably still in a reasonable range.

image.jpg

 

That's a good hand drawn summary "perfect Ackerman" on top and both extremes in two dimensions. With the ackerman aligned with the center of the rear "axle" or centered between the rear wheels, inner and outer tires turn with zero scrub ie they turn in the radius that each travels inner tighter than outer. That's the theory a line through the pivot point for the wheel and the tie rod end pivot center. Things can also change as all this gets dynamic rather than static or theoretical and the struts don't hold everything perfect as suspension cycles. These old cars flex a bit too. I haven't run the numbers on stock or even started design for my car but it definitely will be in the considerations. You've got scrub radius, as well as the caster and camber to deal with too. Lots going on up there.

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1 hour ago, mtnickel said:

I was under the impression ackerman is based not on the distance from ball joint to tie rod, but rather the angle between the spindle (wheel axis) and steering arm.

Additionally, to correct bump steering it's the inner pivot (ie inner control arm mount point) that has to match the inner tie rod joint. The outboard tie rod mount will mainly dictate how long of a tie rod you need.

 

All these rods and points might not be the same length or location but have to move in the same arc and planes as the suspension. If not, then the effective lengths change as things move and bump steer happens. Again, it's all in a 3 dimensional world and the steering has to stay constant in relation to the wheel/knuckle as all of this moves or you toe in or out depending on what each wheel is doing. The double wishbone is easier to control more exactly but a strut is easier to package and cheaper with acceptable changes.

 

There are a couple of really good books on the subject of suspension and some threads out there that are helpful. I'll have to go look at my library and post a few up. Properly designing the rear is one thing but throw steering in the mix and it gets all sorts of complicated.

 

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Posted (edited)
6 minutes ago, jpndave said:

 

All these rods and points might not be the same length or location but have to move in the same arc and planes as the suspension. If not, then the effective lengths change as things move and bump steer happens. Again, it's all in a 3 dimensional world and the steering has to stay constant in relation to the wheel/knuckle as all of this moves or you toe in or out depending on what each wheel is doing. The double wishbone is easier to control more exactly but a strut is easier to package and cheaper with acceptable changes.

 

There are a couple of really good books on the subject of suspension and some threads out there that are helpful. I'll have to go look at my library and post a few up. Properly designing the rear is one thing but throw steering in the mix and it gets all sorts of complicated.

 

Agreed.

 

I find it ironic that my 1st gen mustangs, and my firebird, and my 69 charger all have double wishbone, and my only car known for handling (although my 68 firebird is no slouch in that dept) has a strut.

 

In fact, I find it downright amusing that most modern cars are strut based.

Edited by Invincibleextremes
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2 minutes ago, jpndave said:

 

All these rods and points might not be the same length or location but have to move in the same arc and planes as the suspension. If not, then the effective lengths change as things move and bump steer happens. Again, it's all in a 3 dimensional world and the steering has to stay constant in relation to the wheel/knuckle as all of this moves or you toe in or out depending on what each wheel is doing. The double wishbone is easier to control more exactly but a strut is easier to package and cheaper with acceptable changes.

 

There are a couple of really good books on the subject of suspension and some threads out there that are helpful. I'll have to go look at my library and post a few up. Properly designing the rear is one thing but throw steering in the mix and it gets all sorts of complicated.

 

Ya, it’s all a bit of a mess. The original poster does seem to have a pretty good handle on it I gather. 

The inner pivots needing to match only holds true when the spindle is held static.  But like he said, since the tie rod moved outboard it’s ok that the inner pivot moves as well since our main goal is to have the control arm and tie rod be parallel and roughly the same length. Exciting stuff. If I wasn’t so deep into my setup, I’d be exploring this a whole lot. Brake, suspension, cheap and readily accessible beefy diffs. Lots of pluses. 

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1 minute ago, Invincibleextremes said:

Agreed.

 

I find I ironic that my 1st gen mustangs, and my firebird, and my 69 charger all have double wishbone, and my only car known for handling (although my 68 firebird is no slouch in that dept) has a strut.

 

In fact, I find it downright amusing that most modern cars are strut based.

All in the name of weight and cost savings. Heck, my 93 and 97 accords had double wishbone front and rear!

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1 minute ago, Suchfun240z said:

I am very interested in this setup.  When do you think you will have kits ready to sell? I’m looking forward to reading you write up on front brakes. Thank you for helping us all out! Keep up the good work!!! 

Uncle Sam has me busy for a couple weeks, after that I'm finishing the install on my own datsun, drafting up the shapes once I'm happy with them, and having it all laser cut and see what else can be done.

 

A month or two tops.

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1 hour ago, Invincibleextremes said:

Yeah, I think the best situation for everyone involved is for me to tack every thing in a jig for it to stay true, and let everyone either weld it themselves, or trade favors with a welder etc...  

Are you gonna design the rear knuckles to use 05-14 front brakes? Because that would be sweet. It'd look awesome but more importantly it would be nice for a track car to have a few extra rotors and calipers and it can go on any position of the car.

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What material are you using? Will a mig be able to be used to finish the welding or will a tig be required?  You had mentioned using nissan bearings as well, do they use the same bolt pattern as the mustang parts or do you plan on offering different drilled faces?

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On 6/1/2018 at 11:48 AM, neruve said:

Are you gonna design the rear knuckles to use 05-14 front brakes? Because that would be sweet. It'd look awesome but more importantly it would be nice for a track car to have a few extra rotors and calipers and it can go on any position of the car.

The face itself doesn't accept the calipers, to use 1995 or 2014 rear brakes it will come with a bracket to work with the caliper you want.  So I see no reason why you couldn't use any caliper you wanted, so long as you could make up some sort of bracket to fit.

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6 hours ago, caperix said:

What material are you using? Will a mig be able to be used to finish the welding or will a tig be required?  You had mentioned using nissan bearings as well, do they use the same bolt pattern as the mustang parts or do you plan on offering different drilled faces?

The Nissan and the ford hubs are completely different.  And since techno toy tuning offers a really nice Nissan part for a decent price I don't think I'll be offering a Nissan specific upright.  I could drill the holes for a Nissan hub if needed, but I'm not seeing any reason to bother except for people who really want it for some reason.

 

Still debating on material, meaning towards something mild, to avoid cracking, and definately won't be stainless.  Open to suggestions actually, but I see no reason why someone with a mig and gas bottle couldn't finish it themselves.

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Posted (edited)

If you get this project going with enough interested parties, maybe you could offer it in different materials, for an increase in cost obviously.

 

4130 would be an ideal alloy, great for conventional welding, much higher strength and toughness than low carbon alloys, far better stability during the welding process and the high % of Nickel and Chromium resists corrosion in case customers do not want to incur the extra expense of coatings. Cost would be somewhat higher depending on your supplier, although McMasterCarr has similar size material for similar pricing to low carbon steels.

 

If anyone needs the welding done, shoot me a PM.

Edited by ISPKI

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Posted (edited)

4130 easier to machine than mild steel? Maybe close to the same if annealed which it typically is not. Usually comes normalized which is going to be harder than mild steel, not terrible but definitely harder. If you go to a thinner section it would likely be easier than the large thickness parts. Welding is certainly doable but you need to be more careful with heat zone, ideally post treat to normalize. Choose filler carefully, fit properly, etc. I plan on using pretty much all 4130 on my car on what I add in the cage, floors, etc. It is stronger if treated correctly and can be lighter at the same strength if you go thinner wall. For example I'll use 1-1/2" .095 tubing in the cage where you would normally use .120 wall to get a similar or maybe a little better strength and a lighter part ~20%. But you have to be careful not to make it brittle or soften things up to the point of mild steel strength with the thinner section which is then weaker. And it is MUCH more expensive. Not insane but substantially more for material. 4130 is good for high performance thin walled structure type applications. Any of the energy transfer parts like hubs/axles look at 4340 or even 300M is best unless you get into some of the new "wonder alloys" and proper heat treat. 300M isn't stronger than 4340 natively, it just allows you to heat treat to a higher level without getting brittle which is how you get a much stronger part.

 

4130 might be a good option but cold rolled would likely be fine for most applications. The thicknesses you are showing here are plenty IMO. I'd look at bracing and structure a bit rather than throwing mass at the parts. I'll bet that it could be done thinner and still keep plenty of strength even in mild steel. That saves money and weight. 4130 would be much thinner.

 

Generally you can get more strength three ways:

  1. mass
  2. stronger materials
  3. better design/engineering

The second two are much better for performance. Design is free other than the time to do it which in the business world means money.  But only costs on the initial setup, free on everything after that, maybe even cheaper if done right. Materials - cost is higher raw cost and often higher fabrication/heat treat/procedures. You just have to weigh out what it's worth to you or whoever is going to be buying it.

 

Not trying to offend here, some of that is my opinion but based on facts and how things are done in higher performance applications. Every build on here is done differently and one of the things I really appreciate and enjoy on this forum is the tact that is generally afforded. Everyone's vision and budget is different and there is room for all of that here.

Edited by jpndave
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