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View Full Version : Help me design a roll cage...


Rezarf
04-13-2009, 01:41 PM
Well, this fall, if saving my pennies goes well this summer, I hope to instal a family cage. I am planning on using Metal Tech's front profile bars, they are so ubernicely done, they are a no brainer. If I can convience Ian to let me bend on his bender, I plan on producing the rest of the cage myself.

I like the look of the Metal Tech cage, and a few others I have seen over the years, however, when it comes to what is actually needed to be safe, I am a bit in the dark on how to design one.

Here is what I think I want:

1. If we roll, I want everyone to be protected as much as possible.
2. HREW is probably the steel I will choose. Maybe 2" x .120" tube?
3. I would like at least 6 points to the body (with 4 to the frame) A, B, and C. pillars.
4. I don't want it to look like a jungle gym.
5. Hardtop must still fit... doors too for that matter.
6. I'd like to fab up an overhead console with speaker and CB.


Would you just buy the complete Metal Tech? This isn't an area I want to skim on, but after the front two bars the rest is pretty elementary to bend up.

Thanks, all opinions and suggestions are welcome.:thumb:

Drew

AxleIke
04-13-2009, 02:52 PM
1. I would not get the full Metal tech, just because it'd be sweet to have your own unique set up.

2. I am by no means an expert, so take this with a complete grain of salt, but I've always read, and heard, that for a cage, you run DOM. I've read that it has a better a higher shear load rating, and, since this is your life, its not an area to skimp on. However, that could be totally false, and just some internet hoopla. Just what I've read.

3. I would run a tube with a single bend just above the rear of the truck to the front bars. Then put a down tube right behind the front seats. Run a cross piece across the top behind the rear seats, and at the back. Then just put in a few diagonal pieces for some good, strong trianlges. I'd do one on each side across the space from the middle down tube and the rear downtube. One going high on the driver side to low on the passenger side between the middle downtubes, and then a few across the top.

isotel
04-13-2009, 04:32 PM
Designing a cage is not the most simple of tasks, but if you take your time, you can come up with a unique design that will set your cruiser apart!

I never have liked the Metal Tech Profile Bars, the bends are a bit to radical. Straight Tubes make a cage strong, Triangulation is your friend.

I Like 1.75" tube, and this will meet every Rock Crawling/Racing's Rules.
2" reminds me of the Smitty Built Days :p:

DOM Vs Hrew just do some research online and make up your own mind, Redline now uses DOM in all our cages, we found the price difference to be worth going to DOM.

many things to think about, Doors Closing, Windows rolling up/down, Hard Top/Soft Top, Fitting it into a garage, Visibility from the drivers seat, Impact Points and Stress points, Mounting Seats & Belts, Triangulation & Gussets, Proper Welding, Side Impact Strength, Properly Tieing it to the Frame, Ease of Entry and Exit, and last but not least making it not look like Poo.

treerootCO
04-13-2009, 04:39 PM
I would buy the complete kit from Mark. Tell him we can save shipping by sending my rear 40 bumper along with Subzali's with your order.

Air Randy
04-13-2009, 04:42 PM
many things to think about, Doors Closing, Windows rolling up/down, Hard Top/Soft Top, Fitting it into a garage, Visibility from the drivers seat, Impact Points and Stress points, Mounting Seats & Belts, Triangulation & Gussets, Proper Welding, Side Impact Strength, Properly Tieing it to the Frame, Ease of Entry and Exit, and last but not least making it not look like Poo.

Unless you are set on bending your own, so you can say that you did it, I would go with the MetalTech family cage in kit form. You will still have to notch the tubing, fit it all up and weld it together. Order it with the multiple (4) frame tie-in option points. Get that all tacked together first and that way you know it will meet all of the basic requirements listed above. Then, if you want to start adding additional bracing, tie points, etc you can.

corsair23
04-13-2009, 04:46 PM
...Ease of Entry and Exit...

Definitely something for you to be considering since you will be carting around a little one soon :D - Getting in and out of the rear of a 40 with the hard top on is difficult enough without nearly knocking yourself out everytime. Baby in a baby seat? That could be a challenge :)

isotel
04-13-2009, 05:58 PM
If you Decide to buy a kit, Please consider the Redline Cage and let me know if you have any questions or would like a quote. :D

Rezarf
04-13-2009, 06:22 PM
If you Decide to buy a kit, Please consider the Redline Cage and let me know if you have any questions or would like a quote. :D

Got any pics bigger than a thumbnail? :lmao: :thumb:

I love this cruiser and the cage is definatly something that compliments the cruiser!

treerootCO
04-13-2009, 06:37 PM
Got any pics bigger than a thumbnail? :lmao: :thumb:

I love this cruiser and the cage is definatly something that compliments the cruiser!

Mark did change the design to a halo, not sure if there are updated pics online yet.

Rzeppa
04-13-2009, 07:54 PM
I never have liked the Metal Tech Profile Bars, the bends are a bit to radical. Straight Tubes make a cage strong, Triangulation is your friend.

Are you referring to the A pillar hoop?

many things to think about, Doors Closing, Windows rolling up/down, Hard Top/Soft Top, Fitting it into a garage, Visibility from the drivers seat, Impact Points and Stress points, Mounting Seats & Belts, Triangulation & Gussets, Proper Welding, Side Impact Strength, Properly Tieing it to the Frame, Ease of Entry and Exit, and last but not least making it not look like Poo.

If so, the main reason for making the a-pillar hoop bent around the dash is driver and passenger comfort, and ease of entry and exit. In the real world, straight versus some bending makes little difference. The angle and severity of the crash make much more difference in terms of the physics of how stuff holds up. And 40s are pretty darn strong even with just the stock roll bar in my first hand experience.

Uncle Ben
04-13-2009, 08:11 PM
Are you referring to the A pillar hoop?



If so, the main reason for making the a-pillar hoop bent around the dash is driver and passenger comfort, and ease of entry and exit. In the real world, straight versus some bending makes little difference. The angle and severity of the crash make much more difference in terms of the physics of how stuff holds up. And 40s are pretty darn strong even with just the stock roll bar in my first hand experience.

What makes a difference is building a wheel vrs a box! Never quite understood the "A" pillar hoop theory....seems to me the desired end effect would be to "flop" if possible rather than "roll" or keep rolling....maybe it's just me...

nakman
04-13-2009, 10:28 PM
What makes a difference is building a wheel vrs a box! Never quite understood the "A" pillar hoop theory....seems to me the desired end effect would be to "flop" if possible rather than "roll" or keep rolling....maybe it's just me...

How's that affected by the bent of the a-pillar cage?

I had both a straight A-pillar and then the MT bent one, and wow what a difference that couple of inches makes, especially on the side of the left leg and getting in & out.

Uncle Ben
04-13-2009, 10:38 PM
How's that affected by the bent of the a-pillar cage?

I had both a straight A-pillar and then the MT bent one, and wow what a difference that couple of inches makes, especially on the side of the left leg and getting in & out.

:lmao: Hay mang.....if I wanna be selective and take what I need in a post to get up on my soapbox then the least you could do is listen! ;) :rolleyes:

isotel
04-14-2009, 12:42 PM
Photos of My Cage - this was the Redline Prototype, so the Production kits are a bit different, i can post those tonight. Same Basic design though! and sorry, but our website is coming together slowly.

by far my Favorite shot of my rig ;)
http://i66.photobucket.com/albums/h251/isotel2/Moab%2008/DSCN1134.jpg
http://i66.photobucket.com/albums/h251/isotel2/DSCN1229.jpg

This one shows the Optional Door Bar's and Seat Mounts.. and the amount of room you have getting in and out.
http://i66.photobucket.com/albums/h251/isotel2/photoshoot/tubedoordamage.jpg

isotel
04-14-2009, 12:53 PM
How's that affected by the bent of the a-pillar cage?

I had both a straight A-pillar and then the MT bent one, and wow what a difference that couple of inches makes, especially on the side of the left leg and getting in & out.

Our Kit ends up in basically the same spot on the floor as a MT Cage, the difference is our use of 1.75" tube and Slight Bends let us put the tube in the notch between the door and the Dash pad. rather then bending out around the entire dash, and back in tight to the floor..

Unfortunately with any Safety Item you end up sacrificing some comfort. No one wanted to wear seat belts in the 70's, but we all realized its a minor inconvenience compared to the protection it offers.

we made a kit that was as strong as possible, Minimized any inconvenience, kept the price right, and looked good too.

nakman
04-14-2009, 01:54 PM
Looks awesome! And will the A pillars still work with the thicker hard doors? (75 and later?) that was the one oops moment of my MT, earlier doors were used for fit check then 5 months later I found out my 77 doors wouldn't close.

Not that I even have a 40, but hey just to keep the discussion going... :)

isotel
04-14-2009, 04:55 PM
Yes Sir.. mine is a 76.. doors fit, they are Close :D

Anything to help get the word out. Metal Tech makes good Products, but if your looking for a different option, like our design, and want to support a Local Shop. Give us a call!

MDH33
04-15-2009, 08:36 AM
but if your looking for a different option, like our design, and want to support a Local Shop. Give us a call!


I Really want a set of those doors. :grinpimp:

Rezarf
04-15-2009, 09:40 AM
The "birfield" doors ;) check out the shape of the inner tubes

Uncle Ben
04-15-2009, 10:14 AM
The "birfield" doors ;) check out the shape of the inner tubes

:lmao::lmao::lmao::bowdown::birf:

Rezarf
04-15-2009, 02:11 PM
Here are some of Adam's old cruiser that I really like. Metal tech has more triangulation and Adam's attaches to the dash... :(

I think something like MT's front bars, with something like this out back should be easy enough. I would imagine the hard part being tying the cage into the frame... but still not that hard.

Root, if your reading this do you care if I ask Mark to toss the front bars onto the stuff for you and matt?

Drew

subzali
04-15-2009, 02:42 PM
Drew, MT makes frame tie-ins as well, which make that job just a little easier. There's not much triangulation in those pictures you just posted, I would be a little nervous about it in a rollover; it would more than likely tweak.

isotel
04-15-2009, 03:06 PM
Adam's attaches to the dash... :(

Sweet Rig, Nice Color, and a Horrible way to mount a cage :( the lack of triangulation is no good either.. There is nothing wrong with a simple Boxy looking cage, but the Angled Spreaders will keep it from folding up in a major roll..

I like the fact that i have to step over my Door Bars to get into my rig.. ;) makes me feel safe, Tied In, and Protected.

daisydog34
04-16-2009, 07:15 PM
Sweet Rig, Nice Color, and a Horrible way to mount a cage :( the lack of triangulation is no good either.. There is nothing wrong with a simple Boxy looking cage, but the Angled Spreaders will keep it from folding up in a major roll..

I like the fact that i have to step over my Door Bars to get into my rig.. ;) makes me feel safe, Tied In, and Protected.

I also agree that there is too little triangulation in this cage. The other thing that I have seen a lot of in these MT cages is there is no lateral(side to side) triangulation. I have had to fix customer cages that didn't want this form of triangulation because it would get in the way. They have a semi-hard flop and the whole top of the cage bends. It doesn't necessarily have to be an "X" in the main hoop but gussets in the main hoop and windshield can do the trick.

Rezarf
07-12-2009, 01:20 PM
So I have read a ton about designing a cage. Seems like intersecting tubes and triangles are key. I haven't found any certain answer for why a Halo is better or worse than a non halo design.

Can you guys enlighten me?

Thanks!

Drew

Uncle Ben
07-12-2009, 02:05 PM
I like halo designs because they make more of a box than a wheel. That said I dislike "covered wagon" style family bars like Adams you have pictured because I don't care for the look.

Rezarf
07-28-2009, 12:29 PM
I like this one... anyone know the owner? Seems hardcore ;) :thumb:

Seriously though, UB I like these lines, I would add Metal Tech front profile bars and maybe a halo out back but I like the lines of your cage.

ElliottB
07-29-2009, 11:52 AM
2 crossbars between the A and B pillar would make that cage signifcantly stronger. Didn't these guys take shop class back in high school? Triangulation = teh win!

Red_Chili
07-29-2009, 12:51 PM
The back portion doesn't even look like it would hold up in a gentle roll... Just sayin'. I would be concerned that the rest might parallelogram on you.

Yep, triangulation. Let the design carry the burden, rather than the thickness etc. of the steel.

DaveInDenver
07-29-2009, 01:09 PM
The back portion doesn't even look like it would hold up in a gentle roll... Just sayin'. I would be concerned that the rest might parallelogram on you.
I think the rear tubes might bend in but the main bar and cage I think would very likely hold up.

Maybe the cross bracing a little higher on the tube behind the seat, like nearer to the upper bend, I dunno (say swapping how the rear angling tube and the side angling tube connect). Mostly I'd like to see that since there is no cross member lower down between the main hoop near where the diagonals members tie in. I'd also probably like something diagonal between the fore/aft halo tubes overhead, but probably not strictly necessary.

Really does seem pretty decent and still not look like an erector set, though. I think it's fundamentally all there, nice job. From what very little I know, with the addition of diagonals at the doors this would probably meet NHRA/IHRA 10-point cage requirements.

nakman
07-29-2009, 02:15 PM
Yeah but since there's no rear seat, and no rear passengers, who cares of those back pieces bend in a little? those B pillars look rock solid to me, being triangulated in two directions like that.. that's a fine cage, IMO, for this vehicle's purpose. If this was for the OP, with kid seat(s), then I'd say put another stick across the top in back.

But with no cross bar in back you can still move a refrigerator or hot water heater... :)

DaveInDenver
07-29-2009, 02:22 PM
I should add that with door members (and probably a mid-way horizontal behind the seat), being a NHRA 10-point cage means it would be kosher for under 10.99 cars. Think Wild Rice could break 11? Imelda doesn't even need a bar at all under the rules...

subzali
07-29-2009, 03:21 PM
what's a halo tube?

DaveInDenver
07-29-2009, 05:31 PM
Halo would be just like it sounds, a hoop that goes under the roof from the main bar to the windshield over your head, imagine an angel's halo. Kevin's isn't technically a halo, although the tube running between the two side hoops would be functioning as the halo tube in this case. The alternative would be a real halo, which would be like the bill on a cap over your head. Then there would be two A-pillar tubes that go from behind the windshield to the floor. I think the reason doing a halo is preferred for racing is that there is no joint on the parallel tube that runs behind the top of the windshield, but I guess they are harder to fab.

All cages start with a 'main hoop' typically, then Kevin's design would be called a 'forward hoop' design. The forward hoop goes from the main hoop under the roof line down the A-pillar and to the floor. A halo type would have a 'halo loop' that goes from the main hoop to the top of the A-pillar, across the back of the windshield and back to the main hoop. There would then be two A-pillar tubes from the front corners to the floor. There is a third option where there is a 'front hoop' that goes from the floor up the A-pillar, across the windshield and down the other A-pillar. There would be two side stringers connecting the front and main hoop at the top, under the roof. This is like Adam's earlier in the thread.

I attached a racing halo cage. See the top hoop? That's a halo.

Red_Chili
07-30-2009, 07:09 AM
The back portion doesn't even look like it would hold up in a gentle roll... Just sayin'. I would be concerned that the rest might parallelogram on you.

BTW, it just dawned on me that that is Wild Rice. Duh. There's a lot I cannot see in the pic. If UB designed and built it, it is better than anything I could build.

subzali
07-30-2009, 09:00 AM
Thanks Dave, never knew it would make a difference how it was welded up.

So the Metaltech cages are also a "forward hoop" design, and they do not incorporate any kind of halo.
http://metaltech4x4.com/productsframeset.htm

So is there really any advantage to having the halo vs. say a "forward hoop" design? Does the way it welds up really make a difference in strength? Is that an 8 point or 10 point cage you posted up Dave?

Uncle Ben
07-30-2009, 09:06 AM
Thanks Dave, never knew it would make a difference how it was welded up.

So is there really any advantage to having the halo vs. say a "forward hoop" design? Does the way it welds up really make a different in strength? Is that an 8 point or 10 point cage you posted up Dave?


Let me explain dynamics of a "good cage" by example....
H or O which one of these end profiles would you want to be in when you slip off of that rock on a shelf trail?

subzali
07-30-2009, 09:45 AM
I know you want to be as square as possible to prevent multiple rollovers, I've seen you type that before ;). A flop is "okay", an end-over-end is not.

DaveInDenver
07-30-2009, 11:50 AM
Thanks Dave, never knew it would make a difference how it was welded up.

Does the way it welds up really make a different in strength?
Welds are more likely to fatigue or crack, they are points that are done under less controlled and uniform conditions than the original tube. In a car or closed cab truck they are more difficult to do, so I think there's a natural tendency to distrust them by sanctioning inspectors.

A car roll is likely to be high speed multiple roll and morph from a side to end-over-end or some combination, which is why they are more concerned with a halo than a rock truck that will be more likely a side flop at slow speed. Of course you have to weigh that it might accelerate as in Kevin's shelf road example.

How you then build the cage is also impacted with how you fit the thing in your car, since they are a lot tighter spaces than a FJ40 with it's top off. There's multiple steps, tipping and welding. What a jigsaw puzzle it was when my buddy put his 10-point in his big block Nova. The number of welds and where you have to do them makes certain configurations work better than others.
Is that an 8 point or 10 point cage you posted up Dave?
The attached photo is a 10-point cage.

subzali
08-25-2009, 12:59 PM
Got my basic MetalTech cage done at lunch today...I have a couple tubing mods I'd like to pass by you guys and see what you think/what they do.

AxleIke
08-25-2009, 02:14 PM
Needs some triangles behind the front seats, or it'll fold on a side impact.

Personally, I'd do something across the dash in the front too, and put a diagonal cross piece in the rear hoops.

Also, gussets in all the corners.

corsair23
08-25-2009, 02:26 PM
Dude...You're getting married and I can only imagine that sometime in the near future there will be some kiddos coming along? Unless you are planning to ditch the 40 at that time then why not go ahead and do the family cage thing now at the same time?

More cost now for sure but you won't have anymore $$ in the future than you do now, trust me :D

subzali
08-25-2009, 02:39 PM
Dude, this project is like a long way off as it is, and all I'm really doing is getting some practice at AutoCAD. At the moment I'm kinda thinking that even once kiddos come along the 40 will remain a 2-seater and we will need a substitute for family trips ;) (hint: 80s and even 100s are getting cheap)

At the moment what I have is just a basic cage from Metaltech and I will be adding things to see what works and what doesn't. Isaac, I would really like a bar across the front but am not sure how to do it because eventually I would like to get a locking dash box - most bars go across the top of the dash pad area so a box that opens up there wouldn't work. Still trying to think of how to accomplish that one...maybe have it under the dash pad? I dunno... I will also be adding something that angles up from the foot area to the main hoop as well as triangulating behind the seats as you say...

AxleIke
08-25-2009, 02:51 PM
Dude, this project is like a long way off as it is, and all I'm really doing is getting some practice at AutoCAD. At the moment I'm kinda thinking that even once kiddos come along the 40 will remain a 2-seater and we will need a substitute for family trips ;) (hint: 80s and even 100s are getting cheap)

At the moment what I have is just a basic cage from Metaltech and I will be adding things to see what works and what doesn't. Isaac, I would really like a bar across the front but am not sure how to do it because eventually I would like to get a locking dash box - most bars go across the top of the dash pad area so a box that opens up there wouldn't work. Still trying to think of how to accomplish that one...maybe have it under the dash pad? I dunno... I will also be adding something that angles up from the foot area to the main hoop as well as triangulating behind the seats as you say...

The dash bar is something that I've always hated in the mini world too...

I don't know how a 40 heater system is set up, but to me, the ideal way would be to come down right next to the doors, through the dash, and put the spreader behind everything for an ultra clean look.

As for behind the seats, the most practical, to me anyway, seems to be to go from low on the passenger side to high on the driver. This gives the easiest access for kiddos to get into the back area, or even for access to tools on a 2 seater...Passenger side being the easiest access since there is no steering wheel.

subzali
08-25-2009, 02:54 PM
heater in a 40!? :lmao:

No seriously, a 40 only has a heater in the center, right in front of the shifter, so in theory you could do what you're talking about, except for in my case with the locking dash box.

Why not do a full X behind the seats? Won't it fold if you roll onto the passenger side if you have it the way you describe?

There are pretty good pictures of how the MT cage works on their website:
http://www.metaltech4x4.com/productsframeset.htm

AxleIke
08-25-2009, 02:59 PM
heater in a 40!? :lmao:

No seriously, a 40 only has a heater in the center, right in front of the shifter, so in theory you could do what you're talking about, except for in my case with the locking dash box.

Why not do a full X behind the seats? Won't it fold if you roll onto the passenger side if you have it the way you describe?

There are pretty good pictures of how the MT cage works on their website:
http://www.metaltech4x4.com/productsframeset.htm

Full X is better, but the single triangle seems to be enough, at least from what I've seen.

As for the dash bar and the box, why not just drop it a bit lower, so it would sit with the top of the bar right at the top of the lower part of the dash box?

I'm very surprised the MT cage doesn't have anything behind the seats...Not saying its a bad cage or anything, but from all the research I've done, everyone says the behind the seats triangles are pretty critical.

MT seems to make very good products, so I'd assume they know their business. I'd be curious to see some solid works stress loading on their design.

subzali
08-25-2009, 03:04 PM
What about a horizontal bar across the back of the seats with angled legs like the picture Dave posted a page or two back?

With the dash bar I'm thinking the same as you - just have to see if it would actually work that way and not interfere with knobs, controls, or instrument cluster.

Uncle Ben
08-25-2009, 03:09 PM
design the rear spreader to be a point for your 5 point harnesses even if you don't have them now! From that bar you can design your triangulation. A single diagonal bar is all that is needed. Trouble with an X bar is you end up with one cross bar and 2 butt joints. You add twice as much weight and the butt joint weld will case harden the cross bar, creating a "fault line"

Uncle Ben
08-25-2009, 03:12 PM
What about a horizontal bar across the back of the seats with angled legs like the picture Dave posted a page or two back?

With the dash bar I'm thinking the same as you - just have to see if it would actually work that way and not interfere with knobs, controls, or instrument cluster.

My cage has the two angled legs from the rear spreader. It has stayed tru through 4 flops and one bad roll over. The front hoop has tweaked however and desperately needs some triangulation.

corsair23
08-25-2009, 04:09 PM
There are pretty good pictures of how the MT cage works on their website:
http://www.metaltech4x4.com/productsframeset.htm

This is going to hurt...
14363

I bet this one did hurt :eek:...
14364

subzali
08-25-2009, 04:30 PM
I heard that everybody was out for lunch when that tree fell, so nobody was inside. But it had just been restored so yes it did hurt a lot :eek:

subzali
10-20-2009, 12:24 PM
Latest:

I spent a couple minutes today adding a couple things. I did an Uncle Ben style spreader behind the front seats, plus a bar connecting the A pillar to the B pillar, and triangles in the rear hoops. Comments?

(Drew I hope you don't mind me hijacking the thread - it's all on the same topic so I thought it might help?)

On the second picture I have a Dave-style spreader based on the roll cage picture he posted up a couple pages back, and I removed the triangles from the rear hoops. Thoughts?

Rezarf
10-23-2009, 12:27 PM
I dig these designs...

Rezarf
10-23-2009, 12:28 PM
On the green cruiser especially with something like the Metal Tech from profile bars.

Rezarf
10-25-2009, 09:16 AM
Bump, can you guys tell me how the green one is made? It is hard for me to tell but it looks like the A and C pillar are from the same tube? With the B pillar being a straight section?

I think this is the way I am heading with metal tech's front profile tubes.

So, my question is, can I create a hoop with the B pillar (think stock) and then tie the front and rear pillars into that one, or am I starting to jack with the integrity of the design? I would figure once welded properly it should work either way?

Uncle Ben
10-25-2009, 10:54 AM
Drew, get a hold of Jerry! I think you will really dig the cage that Tyler (daisydog34) and Aaron are building for him!

Rezarf
10-25-2009, 12:47 PM
You got it Kevin, thanks.

Drew

bustanutley
10-27-2009, 03:09 PM
Here is what my cage looks like:
http://home.comcast.net/~utleyz/bvdumped.jpg

and it holds up fine:
http://photos-d.ak.fbcdn.net/hphotos-ak-snc1/hs167.snc1/6280_751974774463_10207317_44243523_6386603_n.jpg

If/When I rebuild, the A-C stringer will be one tube. Having a B-piller hoop sucks, it gets hung up on things, being one smooth surface is superior. As far as HREW and DOM, use DOM on the exterior tubes and HREW in interior bracing to save on cost. DOM it tougher, not stronger, they have identical strength properties but the extra cold working makes DOM dent resistant. My cage is mostly HREW, the A-pillars are DOM. My B-piller is pretty beat up…

farnhamstj
10-28-2009, 09:00 AM
Subzali, might as well plan the family portion of your cage with integrated rear bench mounts too.