TVR Scott
TVR Scott SuperDork
12/16/21 2:19 p.m.

For Kevlar, there are two different grades - ballistics grade is the bullet-proof vest stuff.  What I'm using is laminating-grade, and they're not really the same.  Though a laminated panel of Kevlar is going to be a lot more damage-tolerant than one made of fiberglass or carbon.

Maybe I'm ignorant on this (probably) but is it common that a flywheel blows a cast-aluminum bell-housing to pieces?  I guess I could see the issue on a drag car, but is this a more common problem?

Stampie
Stampie MegaDork
12/16/21 2:55 p.m.

In reply to TVR Scott :

I think it's more of a few guys losing their feet and everyone else deciding they really like having their feet.

JoeTR6
JoeTR6 Dork
12/16/21 2:56 p.m.

I don't think it's very common.  In 17 years of autocrossing, I've never seen it happen.  I have seen a flywheel detach in a Spitfire, but it wasn't catastrophic.  It may be a higher risk for drag racers and track cars, but I'd guess it's related to RPMs.  I run a car pretty hard at autocross and have been known to bounce off the rev limiter just to avoid shifting right before a corner.  But I also don't run my rev limiter above stock levels.  The general forum would be much more enlightened than I.

This picture of a Cortina demonstrates what can happen.

TurnerX19
TurnerX19 UltraDork
12/17/21 9:19 a.m.

I have seen a flywheel explode in a front engine Taraschi Formula Junior. The driver had holes in his pant leg, but no blood loss. We put a big steel plate in my dad's Taraschi first thing after he bought it! I made a trans cover a few years ago for a Gemini F.Jr where the driver's legs straddle the gearbox and it was totally exposed originally. This I did with Kevlar and fiberglass. Painted it up to disguise the too modern materials.

TVR Scott
TVR Scott SuperDork
12/17/21 9:59 a.m.

In reply to TurnerX19 :

Ok, so this whole exploding flywheel is "a thing".  Maybe the next logical course of action is for me to design a Kevlar scatter shield, and then sell a bunch of those to TVR owners too.  Gotta keep my side-gig going!

BTW, I looked up the Taraschi Formula Junior and that is one ugly weird little car!

TurnerX19
TurnerX19 UltraDork
12/17/21 3:38 p.m.

In reply to TVR Scott :

Weird perhaps, but ugly, no way. You probably saw some of my photos if you gogled it too.

TVR Scott
TVR Scott SuperDork
12/17/21 6:17 p.m.

In reply to TurnerX19 :

I apologize.  I shouldn't have said ugly.  They're clearly from a much earlier time - visually more similar to the old beach-racers than anything made more recently.

TVR Scott
TVR Scott SuperDork
12/24/21 1:47 p.m.

Since I fixed her Jetta head/timing belt, my wife gave me the thumbs up to spend some family money on the TVR.  So I fired up the Summit site and ordered a Painless Performance wiring harness and a remote-lock retrofit set.

I've been debating what to do for wiring for a long time, and this seems like a quality, no excuses way to go.  I'm happy.

Merry Christmas, everybody!

bgkast
bgkast PowerDork
12/24/21 2:12 p.m.

Which painless harness did you go with? I'm almost to the wiring stage on my car and am rethinking using a $50 chinesium kit.

TVR Scott
TVR Scott SuperDork
12/24/21 2:52 p.m.

In reply to bgkast :

I got the 21-circuit hot-rod harness.

Slow_M
Slow_M Reader
12/25/21 1:58 p.m.

My brother was revving the 427 4-bolt in his Camaro, with me leaning over the fender, looking into the engine bay. I was in line with the clutch, when it blew. A big chunk missed my head by 4-6”. 

Since then, I’ve heard a number of stories about people being injured by exploding clutches. 

My logic tree, when it comes time to add protection to the TVR, looks like this: In theory, it’s only going to happen when you’re racing. Therefore, no reason to add weight to protect the passenger. If fragments travel up or down, so be it. This leaves only the driver to protect from shrapnel. I was going to add a few layers of ballistic Kevlar on the transmission side of the tunnel. 

Let me know if that logic has a flaw. 

oppositelocksmith
oppositelocksmith New Reader
12/25/21 9:09 p.m.

I know this one is not Triumph engined, but from my discussions with Kas Kastner and other TR racers, they (Triumphs) are prone to shedding flywheels. Comes from the shortage of main bearing support for the whippy crankshaft. 

Take the 2.5L over 6.5k with a stock flywheel and it's coming off.

JoeTR6
JoeTR6 Dork
12/26/21 10:42 a.m.
Slow_M said:

Let me know if that logic has a flaw. 

My only problem with that logic is protecting only the driver.  The reason for that is the number of times I've had a passenger at autocross.  Especially on a track, I'd worry about friends or instructors sitting next to me.

Slow_M
Slow_M Reader
12/26/21 11:33 a.m.
JoeTR6 said:

My only problem with that logic is protecting only the driver.  The reason for that is the number of times I've had a passenger at autocross.  Especially on a track, I'd worry about friends or instructors sitting next to me.

I can’t imagine driving as close to the limit with a passenger as without, but I didn’t think of instructors at all. Thanks for that! 

Gammaboy
Gammaboy New Reader
1/3/22 8:49 a.m.

Just on the topic of "Ballistic grade" aramids vs what you refer to as "laminating grade", aramids used in ballistic protection are suprisingly not necessarily the highest strength grades, but, apart from helmets, are typically a relatively heavy grade of cloth (500+ GSM). Helmets are a finer cloth for drapeability reasons.

5-6mm of aramid (10mm would be better) will give you a fair bit of protection against chunks of flywheel, no matter what the grade is.

As for flywheel failures, the main causes of flywheel failure are:

Over-revving cast iron flywheels or pressure plates

Using a lightened cast iron flywheel

(cast iron, like concrete, is much stronger in compression than in tension, so flywheels are a poor choice for the material)

Cooking a flywheel with a slipping clutch (common in drag racing)

Fastener failure (crank bolts or pressure plate bolts loose/overtightened

Clutch disc failure is also a thing, but tends to stay inside the flywheel.

Given that you're running a modern motor, with a non cast iron flywheel, in a lightweight car, I have to say flywheel failure would be extraordinarily unlikely!

TVR Scott
TVR Scott SuperDork
1/3/22 1:54 p.m.

In reply to Gammaboy :

Good points on the cast-iron flywheel, etc.  That all makes sense.

I'm probably going to ditch the stock used ST flywheel and clutch in favor of a Clutch Masters MX5 unit and a matching chromoly flywheel.  These should be a pretty durable combination.

TVR Scott
TVR Scott SuperDork
1/13/22 10:44 a.m.

I ended up getting orders for two more roof panels, so the engines of industry have gotten turning again.  Nothing I've not documented before, though I did buy more 17 oz biaxial fabric - that stuff is just so nice to work with.

I've turned my attention to the hood repairs.  First up is this mess on the right-front corner - sorry about the blurry pic:

It should look like this:

I've got some ideas in-mind on how to get a mirror-version of the good side.  I've got one crafty plan, and then the fall-back of scanning and 3d-printing a mold.  We'll see where it goes.

Also, I messed around a bit with spider cracks.  This frickin hood is covered with them.  Example A:

You can see on the top right where I took a dremel to a couple of them.  It's easy and fast, though I feel like I'm not going to have much hood left in some areas.

Also, some of the lines that look like cracks seem to be just glass fibers that show up very clearly.

More pics - a couple super obvious ones surrounded lines that probably aren't cracks:

I have many questions on this whole thing, so I'm hoping some of the members with lots of British glass knowledge with chime in (Paging: Roddy Mac and Turner X19).

Is there a way I can improve the contrast?  Like could I wipe down the surface with epoxy coloring-agent, and then wipe the surface with acetone?  The dye could wick into the cracks and show me what's what.  Worth a try?

Once they're ground out, then it's fill with resin/chopped fiber?  Or should I thicken some gel-coat?  New experiences here.

Looking further down the road, should I think about some structural reinforcement on the underside?  Like is this part all spider-cracked because it's old or because it's weak?  The PO did add some fiberglass to the wheel-well area, though it's a poorly done repair that will need removal.

More on the annoying previous owner front, I had a quick look at the front turn-signals.  Short answer, they look like crap.  Gaskets are trash, chrome is rusted, housing is cracked:

And then I saw the Toyota logo.  Screw you, PO.  You suck.

I'm looking into replacements, and have a pretty good discussion going on the TVR owner's board.  The originals are from some old Austin, and are NLA.  Others have used TR7 or Spitfire parts.  Maybe one of the TVR parts houses in the UK has a new version, but it's more modern with clear lenses, not the full orange original version.  No need for decisions right now.

Stampie
Stampie MegaDork
1/13/22 11:20 a.m.

In reply to TVR Scott :

Didn't someone here pour their own lens?  Seems with your skills you could 3d print a mold and make your own. Also another possible side business.

TurnerX19
TurnerX19 UltraDork
1/13/22 12:07 p.m.

Lets start with, do not use un-reinforced resin anywhere as a crack filler. I have used a crack verifying technique by accident when I was rebuilding a Lotus Elite Type 14. I had scrubbed the inside out with water based cleaner/degreaser a few days before I began my first grinding session. As soon as the dust began to fly the cracks showed up, far more, and far deeper into the chassis than I expected. I chased them all out, but the Elite is far more "glass critical" than a TVR body. No one has ever gotten perfection from a TVR's fibreglass. One of my customers has a Vixen S2 1600 that the very best glass man I ever met made into a perfect jewel, completing it about 7 years ago. I saw it Sunday, and you can see print through everywhere now. It also has more woven glass than your car, which is now apparent. Do use a layer of veil continuous strand mat as a final top layer, after grinding the cracks out as shallow as you can eliminating any indicator dye completely and filling with polyester resin and random mat. Try to keep it resin lean, I suspect one of the TVR issues is that they are resin rich, causing brittleness and indefinite shrinkage. I wish I could offer more encouraging insight than all of that.

TVR Scott
TVR Scott SuperDork
1/13/22 2:10 p.m.

In reply to TurnerX19 :

Good info, thanks.

So you think the crack-indicting dye would be worthwhile then?  Based on your accidental experience, sounds like it would help.

I agree that the part looks super resin-rich.  Probably would weigh half what it does now if I were to reproduce it with a lean fiberglass/epoxy lay-up (and I'm tempted).

With the print-thru issues in mind, I ponder the idea of wrapping the car as a final layer instead of paint.  Any thoughts there?  Seems like it could be more durable and tolerant of the idiosyncrasies of old fiberglass.  Done well, it might look every bit as good as paint.

 

TurnerX19
TurnerX19 UltraDork
1/13/22 4:23 p.m.

In reply to TVR Scott :

I think a wrap is a bad idea. If it is truly adhered the print through will show through it too. Also from personal experience with the Porsche wrap shown below, all the leading edges get furry looking pretty quickly. Photo is immediately after completion.  The P-car's carbon fiber door texture showed on a close exam. OK for a race car.

TVR Scott
TVR Scott SuperDork
1/13/22 8:25 p.m.

In reply to TurnerX19 :

Ok, so perfect glass job and immaculate paint job = print thru.

Vinyl wrap over composite = print thru.

Got it!

TurnerX19
TurnerX19 UltraDork
1/13/22 9:23 p.m.

In reply to TVR Scott :

I must say it took several years for the Vixen to show the print thru, and it is probably amplified by the metallic feces brown color. I will try to get a photo of it next time I am working there on his Jag Mk2.

Dusterbd13-michael
Dusterbd13-michael MegaDork
1/13/22 9:27 p.m.

Would spraying something like feather fill over the panels cure the problem? Its essentially super high build primer 

Feather fill may not be the product name I am thinking of but the right concept

TurnerX19
TurnerX19 UltraDork
1/13/22 9:34 p.m.

In reply to Dusterbd13-michael :

This is part of what was done on the Vixen I reference above. The real problem is that the original resin has never completely cured, it is still shrinking 50 years on. It will look great when it first rolls out of the shop. The more sun load it gets, the faster the print thru re-appears.

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