I was researching on how to make stuff with fiberglass...

Im thinking (aka dreaming) of doing a gen1 4Runner cab in full glass.

I want to design it so that it gets "glued up" and that there are provisions for modularity and modifications.

Im interested in understanding how to make the sandwich stronger (Baltek CoreMat verus Alum honeycomb, the need for vac bagging, etc.)

What I am trying to understand is if its feasible to biuld the entire thing in glass/CF mat or should I design it as a glass exterior that gets attached to a inner roll cage made of tradition roll cage tubing.

Now - Im thinking that if F1 can build monocoques in CF/glass it cant be too hard to do without the roll cage tubes. Heck the infamous Chaparals were "hand built" and seem to have held up - even when crashed. And for that matter I was inside one of the V-22 protoypes (its at the helo musuem in West Chester PA) and as far as I can tell thats all CF/glass. (tho granted - if a plane falls out of the sky - yer kinda toast anyway - even if the cabin were to stay intact - people inside the cabin would be mush...)

The thought here is that I would glue up certain items (A and B pillars) so that the interior "trim" is in fact a load bearing member. Heck the head liner would also be a load bearing panel as well.

Are structural glues really up to this?
How are airplane CF wings and stuff attached - GLUE????

Where can I learn more?

 

Comparing a monocoque cf/glass chassis to glass roll cage is just not feasable. Or were you saying using a steel roll cage and then wrapping it with a composite body?

The point of a roll cage in general is to absorb the stress and give a little bit in the process, something glass/carbon fibers just cannot do, bend. Essentially they shatter, but in doing so they basically take all the impact force and disperse it through shattering effects. But I tend to think you know those basics already from what I have read you have read.

Honestly you do not need to vacuum bag a body part, say a fender, in fiberglass...thats usually intended soley when your using an autoclave oven of some sort (which also can be home built by using a large rear section of a uhaul truck and placing a large furnice (preferably electrically heated).

The thing you must see is that most trucks/race cars are just generally steel tube frames with composite bodies. Most of the weight is kept low (center of gravity) hence we use stainless steel under belly trays that weight about twice as much as normal steel or titanium or glass fibers. Not only is it bash resiliant it just keeps more weight low.

What kind of truck are thinking about? A rock crawling chassis with a Gen1 4runner body? Baja type truck? Or just something "cool" to drive around town?

Go a little more in depth into your thoughts. I can help you out in the composites parts and roll cage parts. Check out the website in my signature.

-Jonathan

 

This text wanders a bit – I didn’t have time to write a thesis so IM just jottin down thoughts as I get them.

I currently own a Gen1 4Runner that I’m considering “restoring” to get back on the road.

We now have a daughter and are planning on a second. So Kathy has “safety “ concerns if the 4Runner is to be something OTHER than a “toy / money pit”.

**Vehicle should be “daily driver” usable and keep the 4WD.**

Fiberglass / composite is under consideration mainly due to the “rust proof” nature of the material.

Additional pluses are the ability to shape the material “easily”.

The short range goal is to take make a “Ivan Prerunner”. Yeah – I know Ivan’s original 4Runner PreRunner was a Ranger 2WD frame with a V8 and the rear 4Runner cabin was “stock”.

There are companies that make OEM type panels (toyotafiberglass, B&G) as well as a plethora of companies that make race type fenders (Hanneman).

So much of the buck work has already been done.

To get a 4Runner with Ivan rear fenders I get the 4Runner panels, the Ivan panels, cut and paste the panels together (body lines SHOULD line up) and then pull a new rear buck.

But I have rust on the inside as well – (floor pan etc). Hence the interest in understanding how to go about making a “strong” floor pan with ‘glass materials.

The roof and windshield surround can be pulled off the stock truck. The interior can be fabbed out of flat panels (with added ribs as necessary). Firewall can be fabbed out of flat panels.

BTW - There have been rumors of a complete Gen1 4Runner cab in glass.

**The real concern is if a glue up of multiple panels will be “safe” enough in a crash. I’m not referring to an “race” crash – but a standard on road collision.**

I have played with patching the rust holes with the automotive fiberglass repair stuff. I presume that the real stuff isnt that far removed from the patch process except that the mats are larger etc…

One thought was that if the glass/CF components were glued up in a “double/triple wall configuration a rather stiff shell could be created. But having a super duper shell wont do much for crash protection of the occupants.

Another option is the one you mention – a steel cage with the panels “hung off” the cage – like the way most Baja race cars are constructed.


Suspension:

With the advent of PreRunninng interest, there are now a plethora of off the shelf suspension setups avail. For the 86-96 era suspensions.

Frame – stock with mods as necessary.

Suspension
- Total Chaos IFS (3” wider per side)
- T100 rear axle (3” wider per side)
- Deaver spring under

This means an engine cage and some sort of rear tubbing at the wheels to accommodate the longer shocks.

I thought about a trailing arm setup with the coil overs mounted to the arm (leverage effect), but then Im talking potential cabin intrusion issues, notching the frame for clearance (aka a back half) and the project is getting too complicated. Also I hear ugly stories about four link suspensions “on road”.

Since I also don’t want to be fabricating seats and stuff , the plan is to tub the rear BEHIND the seats and add shock towers as necessary.
The stock roll over bar will be tossed, and a new bar fabbed to deal with the taller tubs and to tie into the shock hoop tops to act as a cross brace. Tie through the body will probably be via body mount style pucks. Wont have the super duper stiffness of a metal to meal tie – but should be quieter.

Engine and drivetrain:

Right now I have a 22RE with the passenger side drive shaft.
There are thoughts of a 3RZ swap and possibly a FJ manual 6 speed (for the AWD)
Also there are some thoughts of a Marlin double box as well. Not a Baja righ but a good “cross” toy / daily driver.

 

OK – sticking to the glass fabrication issues.

What I’m trying to understand is the effects on the materials when it is cut an then rebounded.

For example – on your web page you show louvers being cut into a hood.

Lets say that you have a glass car (aka shell – like say a Mosler) and you installed the louvers in the roof.

Q: does the sharp corner on the cut create a stress riser? Or is the rise not relevant because the panel that is glued back in essentially restores the integrity of the force distributions on the roof (within reason).

Q: when a stressed panel is created (say the roof again) how much of the strength comes from the binders (aka the epoxy) and how much from the matt (glass or cf). I know this is going to vary based on construction etc – but in some general terms. 50% is the mat? 80% is the mat?

Q what is the story on hybrid construction – steel panels and composite panels glued together. (I understand that the Cady CSX has a composite floor pan). So I presume it can be made to work – but just how strong are the glues? Or are mechanical (aka rivets) connectors used in conjunction?

 

Simann:

Sine you have a 2nd Gen 4Runner...
Have you seen this?

http://www.fiberwerx.com/fwx_4rnnr.htm

I want to do something similar to a Gen1

 

1st Question:
It can, but the places the louvers are put in are not high stress zones, or constantly being put under stress. The roof's regitity is in no way increased or decresed by the louvers. The regitity is the cro-moly steel chassis itself under the skin. The skin (body) is meerely there for aerodynamic and marketing purposes.

2nd Question:
The strength of the composite material is a hard one to calculate. Epoxy sets in great around 70-90 degrees with low humidity. Now if you decided to make pieces in the winter in a non heated enviroment the epoxy will take longer to cure and give you a lesser degree of strength.
Though most of the strength comes from the resin itself, the cloth used (kevlar, glass, carbon), each has their own individual tensile strengths and elasticities which can be better suited for different enviroments of usage.

A good book/catalogue to get is "Aircraft Spruce and Specialties". They have a HUGE section of composites, kits to buy and a great table to learn by. You can get a catalogue from here:
http://www.aircraftspruce.com/

Third Question:
"Rivets are only as strong as the riveter". There is a special way to rivet, its not just drilling a hole, buying the right gauge rivet and popping it in there. Bonding two metal sheets with resin and then riveting them together has been done for many years, though nowdays most (race) cars that use this technology forget the rivet part and just glue them together.

Now Honeycomb mats of aluminum/titanium/various steels are used. There are many different resins that can be used in conjunction with certain metals to bond them together better at the molecular levels. Different grades of metals have smaller molecules and different grades of resins have different molecules... etc...

So you must figure out whats the best bang for the buck.

All in all composites technology cannot be learned over night. I would suggest you buying a nice little kit from the Aircraft Spruce company and practice and see what works best for you.

There is no limit what you can do or make it out of, its just how deep your wallat is

-Jonathan Mann

 

Thanks Jonathan!

I have an engineering background - right now Im doing the "back of the envelope" evaluation to figure out which direction to go in.

It seems that for "cost" and expediency reasons the easy way to get this project "done" in my lifetime w/o winning the lottery is to

-- make the primary structure a steel roll cage
-- glass panels are for as you say "for aerodynamic and marketing purposes."

The main advantage of this approach is that there are skilled roll cage fabircators here in PA, but there are fewer experienced composite fabricators here. - Actually there are TONS of composite fabricators here in the Philly area but they tend to work for Boeing Vertrol

I already knew about aircraft spruce. Thanks for the reminder - I had fergotten about that.

At issue for RACE cars as opposed to a "street" car is that there are real short "lifespans" for a race car (one season usually - one race sometimes) but for my project Im thinking of a much monger lifespan. (There was a recent artilce in Racecar Enginnering about the fact that many monocoque chassis used in vintage racing were um - dangerously weak - becuase they were never intended to be raced at that duration - shell was beyond its designed lifespan - and things like bulkheads were seperating due to material degradation... for example foam breakdown inside the monocoque)

 

Well that sure sounds like a plan!

And do not be suprised if your first molds come out kind of "iffy". The hardest part is using/finding a good release.

And honestly, making the molds is the hardest part. Getting all the lines/demensions exactly right so when you pull the plug out it will not have any inconsistancies.

And using a "throw away" paint brush to blot out the air bubbles in each layer of mat (whatever fiber you will be using) as you apply more resin/glass layers will work to your advantage.

And most of all, just be patient.

Its good you have a family to keep you occupied while the fiberglass will be drying, sometimes you can get rather board and start picking at it every 10 minutes looking for a sign of it drying LOL.

For your case, my opinion would be just as you concluded, to use a roll cage type system and wrap it in a fiber body. It will be strong, light weight, and honstly fiberglass has great insulating properties for those cold days!

And if you need any lovers, give me a email/pm

Always neat to hear about others projects. I have to get back to porting out my 7mgte head from my old supra (I just sold). Its going on ebay!

-Jonathan

 

Dude - I HOPE Thats a typo
Im a happily maried man

This project isnt happening any time soon....

Back to the question - I know a composite roll cage type car CAN be built (Mosler) - but the question is - SHOULD I even attempt such a thing?

 

OMG yeah thats a typo for sure! I ment Louvers. There is no "U" in lovers...hahahahah OMG lol ok ok....

maried=married?

Anywho, back on the serious side.

Honestly, if you have never worked with composites at all, though you may have the smarts, its a learned trade. You cannot simply read a book and make a perfect monocoque chassis the first time (well maybe if you were a gazillionaire and had all the tools, then yes.)

I would not want a composite roll cage. Steel BENDS, composites BREAK/SHATTER. Would you want to be in a roll over and the tubing SHATTERS and SPLINTERS around you? Not me! I used to road cycle (and was a mechanic for 4 years at Nashville Bicycle Co. back about 6 years ago ) and have seen MANY composite bicycle frames crack in half. Its not the best material for fatigue and longevity. Its just lightweight. Thats about it.

So yes, call that idea off.
1. Its dangerous for you and the passengers IF a accident occured while your in your composite tube roll cage.
2. Its just too darn expensive if not complicated to undertake for your first composites venture.

Though these are just my opinions. Again I say steel tube frame, composite panals is the proven way and the road BEST traveled.

Overall, just have fun! We only get one shot at life, and to make it actually more fun for us and others we sometimes have to step out of our comfort zones (i.e. financial or personal). So might as well give it a crack!

-Jonathan Mann

 

Thanks for the confirmation of the plan...

I know in F1 and other high end race cars - they DONT appear to use steel cages (Ferrari F1) but then again - they are using "ariframe" techniques, bit "garage" techniques.

The roll cage / panel idea seem to be better becuase I could farm out the main cage construction to a "pro" and then handle the "booger tacks" of body mounting tabs etc to the main cage.

This also means that the panel glue up doenst have to be as "perfect" as the shell is there for "looks" not stucture.

 

Well F1 and even the other Formula and Star Mazda seris use complete monocoque construction. Litterally an inch or two thick of solid carbon fiber/resin vacuum molded and baked inside an autoclave. Thats simply out of the question for most "do it yourself'ers" unless you have...a gazillion dollars

The easiest way to apply body parts on the frame would be with Zeus buttons or aircraft type body hindges and tacks. Aircraft Spruce also has them. You just weld on the connection tabs to the steel frame, rivet the buttons/clips onto the body at the exact location and walla!

Pretty simple task if you have a rivet gun (pneumatic), a drill and a average mig welder.

All in all, if the panals do not line up to your liking, you can always make another mold. Or even use Bondo to build up the lower section of the panal to butt up to the other. These are common practices and the motorsports world believe it or not. Alot of NASCAR teams still use bondo! Of course those are still aluminum bodies, but it works the same with composites.

-Jonathan

 

When I stuck the glass fenders on the 4Runner I re-used the OEM steel tabs that are used to "flat" the fenders. I cut the tabs off the OEM fenders by drilling out the spot welds. I used stainless allen head button bolts to bolt the tabs to the fender ('glass tabs were cut off). Yeah - some of the bolt heads are visible - I think they look cool and if you dont - feh.

I wasnt sure if one could build up a glass "tab" on the back side of the fender and thus "hide" the bolt. I was sort of concerned that the button head would crack the glass over time as the parts shifted.

Toyota fiberglass already makes side panels. So that saves me some work. I plan to reuse the stock door shells.

The cage and then reskin in glass plan also works becuase the cage can be built inside the OEM shell, and then the OEM skin can be "cut off" section by section as I glass in portions...

 

Being a composite materials engineering student, heres my .02. First, I would not really recommend making a cab out of glass fiber. It will not be strong enough in the event of a rollover or serious collision. Do you see any all-composite cars on the road today? No, and there is a reason for that. Fiberglass is great for things like fenders, quarter panels, or bedsides, but making an entire cab out of composite from scratch just seems like a really bad idea. Even race cars and trucks have a full metal frame, rollcage, and chassis; the fiberglass outside is mostly for aerodynamics and to make it look pretty. After producing a few parts from scratch (mold to final part), I would love to see a composite cab, but I just dont think that it is a very feasible or safe idea.