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Old 01-09-2020, 11:17 AM   #1
Missyblue
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Mustang ii help axle centerline

Curious of thoughts. Trying to decide on my new axle centerline. Original was 28.5 inches back. I have read that many move them forward at least 1 inch to center tire when lowered. Heres a mockup of 27.5 I think it looks close. I prefer too far forward than back. The maroon truck is my exact mustang ii set at 28.5 and I find the gap in the front too large so want to move forward. I know the red is slammed I know but looks better centered. Any advice/tips. Thanks
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Old 01-09-2020, 11:51 AM   #2
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Re: Mustang ii help axle centerline

The blue truck looks just right! Now is that your ride height and the wheel and tire size you are going to use?
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Old 01-09-2020, 02:20 PM   #3
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Re: Mustang ii help axle centerline

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The blue truck looks just right! Now is that your ride height and the wheel and tire size you are going to use?
So the ride height will be like the maroon truck so the tires will be a little higher in the fender. But we couldn't get the bar any higher so this is on the level but a little low. And tire size will be this or close just depending fitment. I'm staying. With 15's
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Old 01-09-2020, 05:17 PM   #4
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Re: Mustang ii help axle centerline

Can't tell if those trucks pictured have the wheels straight ahead. Even the slightest turn of the steering wheel makes the tires appear way out of center.
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Old 01-09-2020, 08:58 PM   #5
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Re: Mustang ii help axle centerline

I'm going to say that the red one is close to 2 inches in front of the original axle center line but it may be a subframed truck rather than a MII style setup.

One of my buddies did so many subframe swaps over a 25 year period he lost or quit counting. He would set the axle center line an inch in front of the original and that seemed to look pretty good on the ones that I saw that he did.

It's still your personal preference as to where you set them. It is what looks best to you.

I have to agree that it is super hard to get the front end on an AD or TF set so it looks good parked with the wheels turned a bit. It's one of those little nitpicky things that always bugs me on my own rig.
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Old 01-10-2020, 11:39 AM   #6
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Re: Mustang ii help axle centerline

you need to know the tire size you will use for the final so you mock it up with that diameter of tire. same for the rear, or at least have the truck sitting on stands at the rake angle you want it to be when done. this is because the cross member needs to be installed level at ride height, fore and aft as well as side to side. the lower control arms need to be level in the same manner at ride height. do a frame check before you start looking for out of square and sag. put the stands under it so it will not teeter totter when the weight of the front suspension is removed and also so you have room to work. use a digital level if possible because they are a lot more accurate than a bubble level.
what suspension kit did you go with? just curious because I think some people get sold a suspension kit with drop spindles and it ends up lower than they thought it would be. a MII is gonna drop the truck some to begin with. it seems like the parts guy has his version of what people need for the look that HE likes and then pushes/sells that version more often than others simply because it's what he likes. then the new buyer gets hooked because it's "what everybody is putting in". well, everybody is putting it in because thats what he sells them. some are not happy with the lowrider stance because it bottoms on every curb and it also involves a "C" notch in the rear suspension and possibly a bed floor height rethink.
anyway, long story short, do some research into what will get you the ride height you want and also think about how you plan to drive the truck and on what kind of roads.
attached are some pics of my TCI cross member and how it I installed it. turned out the crossmember was either cut wrong or was the wrong one for my truck-shipped wrong part. not a bunch of help from the vendor or the supplier so I had to figure it out myself as far as what angles were needed etc. another question to ask from your perspective, before purchase. a dimensional drawing would be good showing pivot point spacing etc, I never got one with mine. pics show stock axle center line and 1" ahead of stock. the tire is a 225/75r15. TCI MII kit with 2" drop spindles. possibly not at the same height as a normal TCI unit because I had to trim the cross member to fit my frame.
when assembling use a long level or straight bar and place across the lower control arm pivot bolts to check for side to side level. don't rely on the cross member being made to exact dimensions. also, if you can, get some long rods the same dimension as your lower control arm pivot bolts so you can assemble the parts using the rods which will be longer than the bolts would be. this will enable you to have the rods sticking out of the holes far enough to place a level on them to check fore to aft level of the cross member. again, don't rely on the manufacturer getting that precise when the steel is folded over to make the box of the cross member. if you haven't bought a kit yet I would seriously look at a cross member kit that has the upper and lower control arms welded onto the member already instead of in separate parts that you need to locate and weld on. that way the dimensional geometry work is already done for you and you simply need to locate the cross member and level it, tack it in, then assemble the parts to a mock up stage and see if you like the look in your fender openings. the pics show the home made tool I used to hold things together during mock up. you can't see it in the pics but there is bracing at the frame behind the front bumper as well as cross bracing under the cab. I also built a "caliper" to check the frame rail width periodically to ensure stuff stayed where it should be. one pic shows the suspension assembled with a magnetic digital level on the caliper. notice the upper control arm angle is upward towards the frame? it should be level or downward slightly. otherwise when the truck goes over a bump the tires will angle outward as they go up until the control arm is level, then angle inward after that. this could cause tires to rub if they are already close to the fenders with the wheel offset choice or axle centerline choice. one pic shows the stock axle centerline and the other is one inch ahead. remember that there is quite a bit of room for adjustment so if the mock up isn't done right the alignment guy may move the axle centerline by doing caster adjustments. thats why it is important to get the angles as close as possible during mock up.
yeah, I know, there are lots of guys out there who have done these with a bubble level in a dark garage and a flux core welder. "they drive just fine". in the end it is up to you but some home work and forethought can go a long way in getting what you want. before welding in do a complete suspension travel check with the tires turned all the way-both ways- just to ensure the tires don't rub on the fenders when wheels are turned and you go over a bump.
tip, center punch a mark on the frame as a reference before the old suspension is taken out so you know where the stock axle sat. usually referenced from the center of the stock front spring pivot ahead of the axle. center punch a mark on both sides so your checking is always from a given point, not an eyeballed point.
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Old 01-10-2020, 09:49 PM   #7
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Re: Mustang ii help axle centerline

Dsraven is spot on. Here’s mine 1” foward it a 245/45/18 tire if you go 20s I would only move it .5-.75 foward in my rear I moved the rear back .5 inches
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Old 01-11-2020, 12:39 AM   #8
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Re: Mustang ii help axle centerline

Just to be clear, the wheel size isn't as important as the tire diameter. Try something in the 28 inch area and see if you like that.
Tire size converter site has good info and a comparison tire next tire along with speedo calibration info.
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Old 01-12-2020, 10:29 PM   #9
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Re: Mustang ii help axle centerline

Following. I'm getting ready to start on my frame.
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Old 01-13-2020, 10:43 AM   #10
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Re: Mustang ii help axle centerline

Thanks for all the help. The kit I bought is the one in the maroon truck made by a local company fulltiltstreetrods
I have the hub to hub coil spring kit. Wheels are 15 and tires currently are original 235/75 which is going to stick close to pending room once it drops. The whole rake angle variables seem impossible to figure out haha. Tire size variables and flipped axles drops how far ???? Variables.....and so thatsba tough one for me at the moment. This kit supposedly he says to not stress about that just stress about left to right and it will align just fine. That's TBD I guess
I'll post as I go. I have a gmc so I have to trim my crossmember and keep part of it for my core support so waiting on the tools on that before I proceed.
Sounds like most guys do the 1 to 1.5 forward and my dad says we dont need to reinvent the wheel haha so probably gonna stick in that area.
Slammed57 and dsraven if I can get mine like yours I'll be happy
Thanks again for the advice
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Old 01-13-2020, 03:52 PM   #11
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Re: Mustang ii help axle centerline

Quote:
Originally Posted by slammed57 View Post
Dsraven is spot on. Here’s mine 1” foward it a 245/45/18 tire if you go 20s I would only move it .5-.75 foward in my rear I moved the rear back .5 inches
Did you or dsraven have to do any backspace in your wheels?
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Old 01-13-2020, 08:45 PM   #12
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Re: Mustang ii help axle centerline

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Originally Posted by Missyblue View Post
Thanks for all the help. The kit I bought is the one in the maroon truck made by a local company fulltiltstreetrods
I have the hub to hub coil spring kit. Wheels are 15 and tires currently are original 235/75 which is going to stick close to pending room once it drops. The whole rake angle variables seem impossible to figure out haha. Tire size variables and flipped axles drops how far ???? Variables.....and so thatsba tough one for me at the moment. This kit supposedly he says to not stress about that just stress about left to right and it will align just fine. That's TBD I guess
I'll post as I go. I have a gmc so I have to trim my crossmember and keep part of it for my core support so waiting on the tools on that before I proceed.
Sounds like most guys do the 1 to 1.5 forward and my dad says we dont need to reinvent the wheel haha so probably gonna stick in that area.
Slammed57 and dsraven if I can get mine like yours I'll be happy
Thanks again for the advice
just keep chipping at it and you'll get there. life always gets in the way... family, house, job, low on funds.... just keep getting out there and results will show.... when the funds are low there are a ton of thing to address that just cost some welding gas and grinding discs to keep you busy.... I'll be watching brother .... going to car shows always keep my motivation
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Old 01-13-2020, 10:45 PM   #13
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Re: Mustang ii help axle centerline

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just keep chipping at it and you'll get there. life always gets in the way... family, house, job, low on funds.... just keep getting out there and results will show.... when the funds are low there are a ton of thing to address that just cost some welding gas and grinding discs to keep you busy.... I'll be watching brother .... going to car shows always keep my motivation
Yes for sure! Spent my whole summer sanding and trestimg rust on her belly and inner fenders while I saved for this step! Thanks for the encouragement. Patience is a virtue haha
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Old 01-14-2020, 05:19 PM   #14
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Re: Mustang ii help axle centerline

the pic in the earlier post of my 57 GMC is using the stock aluminum wheels from an S10 4x4 blazer.
I really suggest researching indepenent front suspension angles and geometry before tackling the weld in. it will help you understand what it is you are trying to accomplish in the end and also how everything works together to keep the wheels tracking properly and not rubbing fenders as the wheels travel through their arcs when going over bumps etc. even something simple like an upper control arm installed at the wrong angle can have an affect on if the tires rub the fenders going over a bump at a slight angle turning. since upper and lower control arms are different lengths they travel through different arc lengths so the vertical angle of the tire will change as the wheels move up and down. a lower control arm installed level at ride height coupled with an upper control arm installed with a down angle to the ball joint will cause the wheel to move out at the top, untill the upper control arm becomes level, then in at the top. the lower control arm will move the lower ball joint inwards as the suspension travels upwards.
make sense?
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Old 01-15-2020, 03:47 AM   #15
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Re: Mustang ii help axle centerline

Good explanations above, I will say that in addition to rake and ride height I found that the wheel and tire size makes a difference in the look as well even when the tire is the same overall diameter. In the end I went with about 1.25" forward of the stock location with a 17" wheel. The pic with the roller is 1.75" forward on a 16" wheel.
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Old 01-15-2020, 06:52 AM   #16
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Re: Mustang ii help axle centerline

I think you nailed it.
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Old 01-15-2020, 05:47 PM   #17
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Re: Mustang ii help axle centerline

there you go! looks good ....on to the next hurtle. LOL
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Old 01-17-2020, 12:26 PM   #18
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Re: Mustang ii help axle centerline

sorry, correction on the wheels used. those were not stock S10 wheels but had the same backspacing as a stock S10 wheel from an 02 blazer 4x4. the wheels in the pic also had 215/70r15 tires, just for reference.
in general I think the track width for MII IFS is fairly narrow so a little more space in the wheel well area allowing room to turn wheel with truck lowered using a generic stock back space wheel.
the 235/75r15 was the tire of choice diameter for my original MII swap. the 215/70r15 was what I had on those wheels at the time. I did try it with the 235's on S10 wheels as well but can't seem to find the pic with those wheels on. I sorta "borrowed" the wheels from my son's daily driver and he needed them so they didn't stay on the truck for long, haha.
I'll keep looking for the pics with the S10 wheels and the 235's but don't hold your breath. sorry.
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Old 01-18-2020, 10:50 AM   #19
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Re: Mustang ii help axle centerline

Thanks again for the photos and help so helpful!
I am doing research and doing my best to understand everything so the explanations are great help.

??????So to figure everything out did you do your rear end flip or conversion 1st? From what I read the rear flip will net an average of 5 inches to possibly 7 depending on the truck does that sound right? I also read some do a hanger flip to bring the truck rear back up a few inches.

????What did you do with your rear ends? What amount of drop did you see?

Tire size 215/75 was recommended by the company I wanted tires from but most the guys seem to like the 60's better
But I like sidewall hence the 15 rims haha. The tires I have to play with are 235/75 so maybe need to buy 1 in the size I think I want at the junkyard and mount it per your suggestion to have everything figured out.

Thanks again
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Old 01-19-2020, 07:50 PM   #20
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Re: Mustang ii help axle centerline

my advice,
-decide on a rake angle and ride height
-decide the tire size (diameter) for the truck, front and rear. do engine rpm calculations with diff ratio and trans (overdrive or not) of your choice and decide what you want there as this could have an effect on the tire size that best suits your needs
-set frame on stands at rake angle you decided on. level side to side, do frame checks etc
-decide on where you want your axle center line with regards to the "look" of the tire in the wheel opening for the ride height you like
-mock it up with tack welds and set suspension how it will sit at ride height. use threaded rod to simulate a spring so the ride height can be held where you want/need it. this keeps the control arms where they need to be for geometry to work properly, then install the tires. do you still like the look?
-if you like the look then do the weld in. if you don't like the look do the required changes until you like the look, then do the weld in. trial and error. mock up the tire in the rear wheel opening to match your desired ride height and rake angle. that will give some indication of how much the rear axle will need to move up or down.
-assemble the IFS for real. do mock up alignment
-install complete drive train (possibly minus driveshaft). if this is not do-able then simulate the weight in the right areas so the truck will have the finished weight sitting on the wheels. install mock up weight of entire truck components including a full tank of fuel, seats, rad, battery, spare tire etc etc
-set truck down on it's wheels and recheck the ride height and rake angle. if the rear of the truck is not where you want it for rake angle then do what it takes to get it where you want it. springs, tire sizes, spring hangers etc. remember to keep enough room above rear axle so the axle will not bottom out on bumps. a good suspension snubber is an asset here. if a C notch is needed then you start down that road. you need to have at least 3" above the rear axle at ride height and even that will bottom occasionally. a good snubber, like a urethane bee's nest style used on newer trucks, would be an idea.

my original truck was going to be air ride suspension so totally adjustable from a mock up perspective. with coils up front and leafs in the rear you will need to get the weight of the truck on the suspension and allow it to sit for a bit so the springs settle out. the front end is mock up-able (?) because you know where you want it to be. the variable is the rear suspension ride height and that can be guessed at but you won't really know the actual rear bumper height of your truck until you load your truck's stuff onto your truck. there are a lot of things that can change that in comparing to another truck like yours. new parts, used parts, different manufacturers using different leaf counts or whatever. the important thing is to know what you want to start with, set up the front end for that ride height and rake angle, then adjust the rear AFTER until you get what you want. otherwise it's a guess. an educated guess, but still a guess. the front end is a weld in and has certain geometry rules to follow. the rear end is something you can change when the front end is done.
rear end too high, prolly gonna be the case, you can change axle to be above the springs, change spring shackles to different length or change the hanger for the shackles to be in a different location. you can change the forward spring hanger mount locations on the frame or change the design of the spring hanger to incorporate a different spring pin height location with relation to the frame. do driveline angle adjustments accordingly after you get it figured out. angle of rear axle pinion u joint needs to match (but be opposite) the angle exiting the trans.
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