Rolling Thunder Part 7: Independent Rear Suspension Install & Upgrade

Today, we're installing a Mustang cobra independent rear suspension in our Ranger based pickup project Rolling Thunder. Then we're picking pads and rotors for the street and for the track. It's all today here on trucks and more aggressive yellow stuff pads.

Hey guys, welcome to trucks. Today, we're back on Project Rolling Thunder, which is our attempt to turn an 01 Mazda B 2504 cylinder plane, Jane pickup truck into a powerful forced induction V8 manual six speed transmission street and track machine. Now we're obviously getting away from the budget a little bit because that was stage one of this project and we're gonna

spend a little bit more coin this time around, but we're gonna try to do it wisely. Now, part of that sinister plan is to take tried and proven high performance racing parts and fundamental techniques and apply them to this chassis such as the independent rear suspension that we borrowed from the 04 Cobra. Now, another place that we drew some inspiration is from another track prepped V8 Ford Ranger that was featured on power block not too long ago.

This 95 Ranger belongs to Matt Boar

of both

are racing and fabrication. And it's a little bit of inspiration for us in our project,

the functional splitter and full on roll Cage, make this a 100% race track powered by a three or two car V8

C front and

suspension of Mad Own design. Make this truck handle like crazy.

Now, just like you guys, we don't have a frame jig or a frame table to work off of. So we're gonna use a flat and level section of our concrete shop floor to get the job done.

Now, the last time we had our truck in the shop, we took the body set it down on the bare frame and selected our ride height and we just welded on these stands, which is nothing more than a piece of tube, a nut and a washer weld to do it and then a bolt on the bottom. So it's threaded and height adjustable. That way we can level out the frame and make sure everything's right.

Now, the first step in installing our IRS sub frame is gonna be to remove all the shock mounts, leaf spring hangers and brackets that are gonna be in the way that way we've got some clean and flat real estate to work off of.

Now, our favorite way of removing the stubborn factory frame ribbon is to cut an X in the head and use a sharp chisel on our air hammer

makes quick work of it.

All right, we've got the rear spring hangers and shock mounts knocked loose from the frame. But before we remove this front spring hanger, we wanna make sure this is tack welded together and nice and solid. If you take a closer look, you can see this front frame, half and rear frame, half overlap and are attached at this point by this cross member and about six or seven rivets, four of them holding this hanger in place. So just to be extra cautious and make sure nothing moves around, we're gonna weld this up to make it solid.

Yeah.

And we wanted to compare the weight of our cobra IRS suspension system with the stick axle in springs that we took out of the ranger just to show you the difference. Now, our cobra system minus brakes weighs in right at

309 pounds

in order to get an accurate representation of what they say. We with breaks springs, all that kind of stuff. Well, we're just gonna actually stick it on the scale.

We got a spring,

another spring

caliper caliper

rotors

and

don't forget the pads

that brings us to

wow, 367 pounds total weight.

Now, the stock Ford 7.5 inch rear axle with brakes, leaf springs and shackles weighed in at about 260 pounds, meaning we picked up a solid 100 pounds. And why are we excited about that when we all know adding weight to a high performance vehicle is kind of counterintuitive.

That's because we're adding it in the right spot. If you guys remember the stock version of our truck, as well as stage one had a 62 to 38 front to rear weight bias, not good for putting power through the rear wheels. So by adding 100 pounds to the back, we're gonna help with that weight bias. We're gonna lower our overall center of gravity.

Now, with the entire independent rear suspension completely disassembled. Ryan's gonna grab the sub frame and get started on the installation.

Now, the biggest mechanical advantage to an independent rear suspension is that when one wheel moves, it doesn't affect the other wheel, unlike with a stick axle, when one wheel travels up, the other one has no choice but to react and to move kind of along with that. So an IRS has a handling advantage right off the bat, but it gets better because it's tunable

and just like a front suspension, there's an upper, lower control arm with the upper having an adjustable eccentric which allows you to change the camera setting or the tilt in of the wheel and tire at the top. Now, another tuning point on this system is the adjustable tire rod which gives you a tow in adjustment and

helps you really control the way a vehicle tracks with the system.

Now, the cobra systems like this have a slightly larger sway bar than the GT

along with the beef here, 31 blind CV, half shafts. And of course, the giant

lower control arm that's cast aluminum. Now, as good as this system is, the aftermarket allows us to make it even better. I've left this side completely assembled to show you where we can improve it.

Now, the spindle or upright has a spherical style, upper and lower ball joint and they're not worn out and fairly precise. So they're gonna stay, but the upper and lower control arm bushings, well, they're made out of rubber and although they offer a nice smooth and vibration free ride,

they're mushy and they contribute to wheel hop. So they're going away.

Now, this guy as well as being a giant weight

is a vibration damper that was put there by the Ford NVH engineers to help control noise, vibration and harshness. Well, quite frankly, we're just not as concerned about that as we are about controlling the wheel hop issue and improving the handling. So this guy goes away as well as these rubber isolators that connect this dampener to the third member and lock it into the chassis. Well, they're going away too.

So when we come back, we're gonna show you exactly how we're gonna improve on a system that was already really good from the start.

Welcome back to trucks where today we're installing an 03 Mustang cobra independent rear suspension system

underneath the back of our

Oone Mazda B 2500 ranger based truck, all in an attempt to make this pickup handled more like a car.

Now, once we get the Subra located and positioned where it needs to be, we can weld on some brackets to attach the sub frame.

But like Kevin told you earlier, we've got to address the factory compromises and shortcomings of the set up and with the help of the aftermarket, we can make this system even better.

Now, if you remember

we use the maximum motor sports oil filter relocation kit in our Marauder engine in stage one, but their strength really lies in Mustang performance suspension system upgrades. So since this is a Cobra, IRS, what we had them send as a kit to help beef it up.

This is their grip pack IRS upgrade and replaces the factory rubber bushing sleeved in steel with these Del RN bushings very hard compound with a hard

anodized aluminum center pin for strength and lightweight.

They also send enough shims to get a very precise realignment when you install the new system, lubricating grease, a scuffing pad to clean out any debris or corrosion from the control arms without distortion, even a pair of gloves to keep this nasty stuff off your hands. But the best thing about the kit is that they send an installation and removal tool with the kit makes it pretty easy.

Now, the control arm bushings are different sizes, so match up your removal tool to the bushing with the test fit and follow that by the spacer washer and nut

and snug it up by hand.

Then using hand tools, slowly tighten the nut and the assembly. It's important not to use pneumatic tools. So you don't force any distortion into the aluminum control arm.

Now, it may take a while, but you're gonna know when the bushing comes out.

Aluminum control arms are lightweight but aluminum is soft. That's why they provide a scuffing pet. So you get rid of the schmutz and the corrosion and you don't distort the aluminum. It's very important that you have a nice flush fit with the new Delery bushings.

Now don't confuse Delre with Urethane. It's a much higher diameter and does not compress

dry was actually invented in the fifties by Dupont and is used as a bearing in hot wheels pretty cool.

Now, this is gonna work great for us for a test fit. And by the way, don't forget some anti

on the bolt threads and in between the washers make sure everything doesn't bind.

Now, the shims and the lube that happens on final assembly, the shims really are only there to take up any slack that may have been created by eliminating the rubber bushing. So for now, this is gonna serve us very well and I've got a few more of these things to do.

All right, with the sub frame blown apart and the frame ground down to bare metal in a couple of spots where we can finally get to the installation of this thing.

Now, we knew where to locate it and how to position it based off of measurements that we took and from the information we gathered from the helpful and knowledgeable tech guys at maximum. Now, before we disassembled the stock truck, we measured where the rear axle center line was of the leaf sprung,

solid axle pickup and that's right here. Then we also determined the axle center line of the independent rear suspension system and match things up.

Now, the first thing we're gonna do is install and weld in some temporary bracing to lock the sub frame in place. Then we can get to work making up and fabricating some mounts to permanently mount the sub frame, but it's still gonna be bolted and it's still gonna be removable.

Now, after measuring and measuring again and triple checking and measuring again, we determined we had the Subra sitting at the exact ride height and location that we needed. So we just locked it in place using some one inch angle iron

and these will serve as temporary braces until we can design and cut out some permanent brackets using our torch m

Hey guys, welcome back to the shop. While Kevin was working on the control arm bushings, I had a chance to make up a cross member and some brackets so we could locate our sub frame. Now, like we told you earlier, this thing's got to be removable. So it took a little extra time to make brackets that would bolt into the frame, but it's gonna be time well spent if we've ever got to work on any of these suspension parts that require a little extra clearance. So let me show you what I've done.

Now, the first thing I did was plasma cut a couple of holes in the backside of the tubular Subra

and that will allow us to install this plate with two half inch grade eight captured nuts welded to the back side of it.

Once that's welded solid, we've installed our cross member which is a piece of inch and three quarter dom tubing that we've bent up on our hydraulic tubing bender along with some 316 plate, we cut out using our torch

and

once everything is welded solid, we can install the cross member on the inside of the frame rails and weld it up for good.

Now, if you notice the location of the cross member mounting points, well, the right here above the lower control arm, pick up points. And that's because that's where a lot of the suspension energy and load is going to be transferred. So doing it right here will eliminate any Subra deflection often found in the factory. IRS set up

the front half, we did a little bit differently. This is a piece of inch and a half dom welded directly to the sub frame and then again to the bottom side of this bracket and that'll handle any vertical loads, any side to side movement will be handled by this piece of one inch 3/16 walt dom again, welded to the same bracket. We've got a couple of captured nuts welded to the inside of the frame rail, a gusted for strength and this thing is removable and still plenty strong, but we're not done yet.

Now, just to make sure this sub frame is installed as rigidly as possible. I went ahead and added another piece of plate in between the upper control arm mounting points.

This top piece will become the bracket that's welded to the frame rail. But before we do that, we've got to notch the frame for upper control arm clearance. Once we do that, we'll box in the remaining section of the frame rail and add the necessary gussets.

Now, the benefits of having these brackets at the frame or even in board of the frame is that it allows us to remove the Goofy Flex Prone factory Subra end. Now, this thing was designed to fit an existing Mustang platform and now that we don't need it,

we get to cut them off.

Now, the things that limit running really wide tires and wheels on the back of a Mustang are both the shock and the forward Subra

mounting point. So by eliminating these, we give ourselves more options for fat rubber

Now, I wanted to show you what the rest of the components in the maximum Motorsports grip pack look like as well as what a little bit of elbow grease and paint can do for the appearance of this stuff.

Now, the stock sway bar and links are going away to be replaced by the maximum lengths which are billet, aluminum and hind jointed for adjust ability of sway bar, preload. The stock CV have shafts. Well, there's nothing wrong with them but we immediate blasted them and threw a coat of paint on. They're good to go.

The upper control arms have the Del RN bushings set into place. We also media blasted and threw a coat of paint on them. They look pretty good.

Now, the lowers, we blasted them as well, but we didn't paint them instead of painting, we put a barrier coat called shark hide. That's supposed to keep it from oxidizing and keep the appearance of aluminum pieces and other raw metals looking good. We're gonna test it out and see how it works.

Now, the 8.8 pumpkin just got cleaned up, but the rear isolator which is rubber gets replaced by a solid billet aluminum piece just as the front left and right. Isolators are replaced by, again, solid but adjustable billet pieces.

Now, the last pieces of this puzzle are in the stock high rods which get replaced by these lightweight hard

anodized billet aluminum rods again with high joint ends that are bumps to your adjustable. Now, all of these pieces will virtually eliminate any wheel hop issues that we may have had with the stock system and look pretty snazzy doing it.

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There you go.

Hey guys, welcome back to trucks where our independent rear suspension install is just about complete short of a couple of gussets for the upper mounts. Now, everything's assembled and loosely bolted together and everything fits just like it's supposed to

and it looks pretty good too. But let's take a closer look at what we did for upper a arm

and what we did to finish off the upper Subra mounts.

Now, once we were happy with the amount of frame we trimmed for a arm clearance, we went ahead and played at the bottom of the rail and boxed in the remainder.

Then we just added these vertical gussets for our upper Subra mounts.

Then to finish things off, we added this top plate for strength

and to help out in the looks department

and well, obviously boxing the frame rails from this point forward.

Now, if you're doing a project, anything similar to this at home and you're worried about compromising on strength. Well, there's no need to think about this. The factory IRS Subra assembly was held in place with just four bolts. Here. We've got 12 of them. So those 12 bolts along with the cross members, brackets and bracing that we've added, I'm sure we've significantly increased the stiffness of the sub frame itself and this entire frame section,

which is a good thing because this truck is gonna get hammered on.

Now, it doesn't make any sense to do all these chassis upgrades along with a supercharged high horsepower engine and not pay attention to the brakes because trust me, we want this thing to stop. So out back, we're using Eb C's Dimpled invented Cobra rotors. Now we're using a bit of

strategy here because we've picked up an extra set of rotors and

their red stuff and more aggressive yellow stuff pads. So once we bed in the paths to a specific rotor, well, they become a match set. So we can easily switch depending on where we're driving from a street to a track set up.

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