BRZ Rally Car

Not sure where your experience lies with this kind of stuff, but I found Kevlar really isn't very different to work with than FG or carbon.

I always had two sets of scissors - one for glass and carbon and a second set for Kevlar only.  They wear scissors differently and if you use separate sets the scissors last much longer.

I liked to put my fabric down on a piece of plastic film, wet it out there, and then put a second piece of film on top.  Like this:

Once the fabric is covered with the second piece of film, you can trim the edges to make the patch or section the size you want.  You can make some intricate patches this way by transferring a template to the film.  Kevlar really likes this method.  It can be tough to scissor cut, but once it's wet out and supported by the plastic film on both sides it cuts just as well as other reinforcements.

Then you peel one side of the film off and apply the whole thing like a big sticker:

Much easier than fighting a big piece of sticky cloth.

Bonus points for vacuum-bagging!

(Composites nerds out there: yes, I know the port is over the part.  No it didn't clog.  Yes, I know it's better to do it off the part.)

In reply to ¯\_(ツ)_/¯ :

I haven't made any parts this way.  Are the oem mounting holes in the plastic going to be strong enough?  even reinforced with carbon kevlar?  I can imagine myself building an unbreakable kevlar skid plate and then having it ripped off the mounting points on the first contact:)

In reply to TVR Scott (Forum Supporter) :

Four years of FSAE with lots of carbon fiber involved, but that's pretty much where my experience ends.  We actually layed up the chassis by hand my junior and senior years, using a very similar technique to your first and second steps there.  I don't think I'm going to attempt vacuum bagging for this, if only because I don't want to buy the extra materials- I know it won't be quite as strong/light, but if I go this route part of the annual maintenance is probably going to involve removing these panels and brushing another coat of epoxy onto them to build back up what has been removed by gravel.

In reply to Jah29 :

I was thinking about that- the fuel tank fasteners are pretty chunky and probably won't present an issue.  The fuel line protection should probably get additional fasteners, though.

Just my $0.02 on composite protection parts. The composite guards should be strong enough to do the job. The biggest drawback is abrasion resistance. Maybe not such a big issue on a RWD car, but FWD cars shower the underside with rocks and sand and then the composite protection parts turn into a ragged ugly mess. Even Kevlar as the resin gets worn away.

Could you spray the bottom of a composite guard with bedliner?  Give it the abrasive toughness?

In reply to TVR Scott (Forum Supporter) :

Probably, but if the topmost layer survives to get another layer of epoxy it's not a big deal- repainting the wheel wells and undercarriage is an annual thing anyway, this would just be another panel with a different "paint" to apply.

sounds like its worth building up the epoxy to act as an ablative layer, so that the glass/kevlar dosent get blasted by rocks, you can just scuff and add a few more layers

In reply to Gaunt596 :

I wouldn't really look at it like that.  There shouldn't discrete layers of epoxy and reinforcement.  It's all combined into a unitary structure.

Epoxy isn't at all good at being an impact layer.  It's weak and brittle, and doesn't really stand up to impacts.  It's meant to only hold the fiber layers together so that they can form a rigid structure.

That was why I was thinking about bed-liner.  It is rubbery and soft and made for taking impacts.

HDPE, its cheap and its easy to work with. weld nuts and small patches of metal make a secure attachment.  it takes allllll the abuse. and when that piece is done (still going on 8+ rallies with mine unchanged) you have a perfect template to replace with a cheap piece of plastic again.

TVR Scott (Forum Supporter) said:

Could you spray the bottom of a composite guard with bedliner?  Give it the abrasive toughness?

that will just be sandblasted off eventually. or after 1 rally

In reply to fidelity101 (Forum Supporter) :

You guys know the requirements so much better than me.  I'm just throwing out some ideas.

I'll agree that HDPE is fantastically tough stuff.

Once the fibreglass or carbon fiber surface layer is abraded away the Kevlar bursts outward like super tough grass. Then if you want to repair it you must vacuum bag to compress it back. Never use Kevlar as the most exposed layer for this reason. When making body parts that saw much gentler service I used a thin glass layer both ides of the Kevlar if space was at a premium, or carbon fiber if I could go thick. It sounds cool, but it is a lot more labor and material expense for a part that will require a lot more maintainance than HDPE.

I can see how HDPE would be a good choice for under the fuel tank- it really only needs to resist abrasion and punctures there, since the tank has some give to it.  I think I'll need some sort of channel over the fuel lines, though, since they need to be able to survive a big hit without getting pinched shut or split open.

I'm abandoning the kevlar idea for now and will keep thinking about how best to do this.

In reply to ¯\_(ツ)_/¯ :

Make HPDE channel or L section by screwing a 3/4 square strip on one or both sides of the facing plate, Use 1/4-20 flat head screws and recess the heads 1/8". Threaded holes in the 3/4 strips. About one screw every 6". Occasionally you can use a long screw to facilitate installation as well as part fabrication. 

In reply to TurnerX19 :

I think I'm going to attempt to make a steel channel for the first try- as far as hardware, I've been cautioned a number of times about any sort of flat head fastener on the bottom of a rally car.  It seems to make sense for ground clearance, but if it gets mangled by a rock there's nothing to grab to remove it unlike a regular bolt where you can at least put vice grips on whatever is left of it.  Not a fun predicament during a 20min service.

In reply to ¯\_(ツ)_/¯ :

Having had to remove a mangled button-head bolt from a skid plate, I agree.  Standard hex-head bolts may slightly reduce ground clearance they are much more durable. 

Some day I'll find the guy at Minimania who decided an 8mm stainless steel (and somewhat soft) bolt with a 6mm hex was a good idea for their MINI skid plate and slap him in the face.  Whenever I installed those plates for friends, I replaced the supplied bolts with regular bolts - since I ended up with like 25 of them from Bolt Depot.

Snagged more 15"VW wheels last night- I have 16 of these now.  Need to paint them white whenever it stops being super humid out:

Lots of the R5s use carbon/Kevlar in high wear areas. Kevlar (nomex) is a ton more abrasion resistant than carbon alone.

Humble brag on the Fiesta I was co-driving in last weekend in Ojibwe, and then also McKenna's Skoda which use Carbon/kevlar bits:

In reply to TXratti :

How often do they have to replace those pieces, I wonder?  And yeah, just go ahead and keep casually mentioning that you get to ride around in an R5 car.  

In reply to ¯\_(ツ)_/¯ :

Probably every few rallies tbh.

And yeah, let me know if you get tired of hearing it!  I still pinch myself.

In reply to TXratti :

Honestly, if you have pictures and can provide voiceover I would love to read an "I know stuff about R5 cars, here it is" thread from you!

In reply to ¯\_(ツ)_/¯ :

Ha, I'm not sure who all would want to follow that or what anyone would want to know. Slightly too fancy to be "GRM"?

TXratti said:

In reply to ¯\_(ツ)_/¯ :

Ha, I'm not sure who all would want to follow that or what anyone would want to know. Slightly too fancy to be "GRM"?

I would love to hear/read that thread! GRM just means playing with race cars, whatever budget :)

bluej (Forum Supporter) said:

TXratti said:

In reply to ¯\_(ツ)_/¯ :

Ha, I'm not sure who all would want to follow that or what anyone would want to know. Slightly too fancy to be "GRM"?

I would love to hear/read that thread! GRM just means playing with race cars, whatever budget :)

Or GRM means playing with other peoples' high-dollar race cars!

I'd follow along too.

TXratti said:

In reply to ¯\_(ツ)_/¯ :

Ha, I'm not sure who all would want to follow that or what anyone would want to know. Slightly too fancy to be "GRM"?

I'm in for that too for sure