AWSX1686
AWSX1686 SuperDork
4/24/19 8:44 a.m.

I am planning to put Aerocatch hood pins on the drift e28 (build thread). My original plan was to use 4 sets of them, to eliminate the hinges completely, and just have the hood be completely removed when opened. Part of this is because the hinges were messed up, but also weight reduction. I'm pretty sure if I went this route I could gut some of the under structure of the hood too to make it more lightweight. 

 

My only concern is if any racing sanctions will throw a fit about this. I'm pretty sure I've seen it done before, but is it a good idea?

wae
wae SuperDork
4/24/19 8:49 a.m.

Can't speak to sanctioning but functionally it is both awesome and irritating.  

Awesome: Total access to everything under the hood.

Irritating: Taking a quick peek means pulling 4 pins, lifting the hood up and out of the way, and finding a place to put the hood.

WonkoTheSane
WonkoTheSane Dork
4/24/19 9:00 a.m.

I'll second Wae's comments.   The other irritation is that on approximately 98% of the cars I've raced, within a season the gutted hood is now a bit hard to slide onto one of the pins.  This problem is logarithmically more difficult with 4 latches, not linearly...

Also, if you go this route, put some cut rubber tube or tape or something on the leading edge of the hood and some strategically placed strips of flat rubber on the hood so you can always pop it off and lean it against the car without scratching both to hell because you need to check your oil at a pit stop.

Oh, that's the other thing, plan on this adding ~20% of time to your pit stops as the crew flops around with the awkward hood, hits a teammate in the head trying to slam it back into position, etc.

AWSX1686
AWSX1686 SuperDork
4/24/19 9:13 a.m.

Those are the downsides I was anticipating. I think I am going to have to keep on with the plan for 4 hood pins, as I'm fairly sure I scrapped the hinges already, but they were damaged and didn't work well anyway. 

I don't think I'll gut the hood right away. There are other things that have higher priority before Carlisle towards the end of May, but I'm thinking they'll want me to have a hood attached.

ross2004
ross2004 Reader
4/24/19 9:15 a.m.

The 20% of the time it's helpful does not outweigh the 80% of the time it's a pain in the ass. I went the no hinge route originally on my Lemons e30; eventually I put some stock car style hinges back in and never regretted it. 

rslifkin
rslifkin UltraDork
4/24/19 9:16 a.m.

I'd definitely keep hinges of some form.  If you want better access at times, maybe consider a way to easily release the hood from the hinges for total removal.  But for quick oil checks, etc. being able to just flip it open will make your life much easier.  

Streetwiseguy
Streetwiseguy MegaDork
4/24/19 9:31 a.m.

Is it windy where you are?  Watching your hood fly across the pits and smack someones car is not great.

If you keep hinges, it just smacks your own roof.

AWSX1686
AWSX1686 SuperDork
4/24/19 9:31 a.m.
ross2004 said:

The 20% of the time it's helpful does not outweigh the 80% of the time it's a pain in the ass. I went the no hinge route originally on my Lemons e30; eventually I put some stock car style hinges back in and never regretted it. 

How did you mount those on your e30?

Wally
Wally MegaDork
4/24/19 9:38 a.m.

I have hated every car that didn’t have hood hinges. I found gutting the hood, reinforcing it with some light 3/8 inch tubing, and making simple hinge tabs to be a good compromise of weight savings and ease of use.

John Welsh
John Welsh Mod Squad
4/24/19 9:40 a.m.

Hood off every time is not really easily a one man job.  Will you have two people every time?  Are you okay with some scratching of the car body and hood?  

frenchyd
frenchyd UltraDork
4/24/19 9:51 a.m.

In reply to AWSX1686 :

All the above is true, plus the edges of hood pin mounted hoods take a beating when you set them on edge to work on the car.  If you lay them flat someone sooner or later will either step on it or trip over it, or both!  

There is an alternative.  2 posts, 2 pins.  That way when you set it down it’s on the posts. Edges are OK  

 The posts go in horizontally either into the firewall or into the radiator core support.  You can also use strap instead of posts.  

Finally you need to learn to do fiberglass. A fiberglass hood as strong as a stock one will weigh about 1/2 what a steel one does.  

That’s fiberglass Matt.  

You can also do fiberglass cloth and save a little more weight, or replace the cloth with carbon fiber and save some more weight.  

Material costs for the Matt to make a mold will be less than $100 about 1/2 of that if you buy it from a wholesale supply house.  It will take you a couple of hours to prep the part to make a mold.  Waxing and spraying on PVA ( a release agent that washes off when you’re done)  

cloth will cost about 20% more and carbon cloth another 50% over that. But each reduces weight.  

 

Once you have the mold you need to make the part. That will take about the same amount of time as making the mold.  

Using matt, cloth or carbon cloth is the same amount of time.  

No you don’t need prepeg, vacuum bagging, and an autoclave unless the last few ounces are worth a lot to you.  

There are plenty of U tube how too’s  or ask I’ll walk you through the process  

 

ross2004
ross2004 Reader
4/24/19 10:58 a.m.
AWSX1686 said:
ross2004 said:

The 20% of the time it's helpful does not outweigh the 80% of the time it's a pain in the ass. I went the no hinge route originally on my Lemons e30; eventually I put some stock car style hinges back in and never regretted it. 

How did you mount those on your e30?

With a welder.

AWSX1686
AWSX1686 SuperDork
4/24/19 11:12 a.m.
ross2004 said:
AWSX1686 said:
ross2004 said:

The 20% of the time it's helpful does not outweigh the 80% of the time it's a pain in the ass. I went the no hinge route originally on my Lemons e30; eventually I put some stock car style hinges back in and never regretted it. 

How did you mount those on your e30?

With a welder.

I meant positioning. I guess your e30 hood probably opened forwards. I'm just not picturing how I could make that work with the e28 hood. The corners closest to the windshield stick out into points, so the stock hinges tilt the hood, but also move it forward and up so that those point clear. Best I can tell at least. The hinges you linked have a single pivot point, which would be nice and simple, I'm just trying to figure out how to make that fit. Maybe if I made the hinges mount right at those corner tips...

MadScientistMatt
MadScientistMatt PowerDork
4/24/19 12:05 p.m.

Frenchyd makes a good point: A hingeless lift off hood makes a lot more sense with a lightweight composite hood than a piece of steel.

I've also heard of lazy hood making by using the stock hood as a mold, just laying down the fiberglass on top of it. Finish isn't as good, but it takes less time.

ross2004
ross2004 Reader
4/24/19 12:43 p.m.
AWSX1686 said:

 The corners closest to the windshield stick out into points, so the stock hinges tilt the hood, but also move it forward and up so that those point clear. 

It's a Lemons car, you just cut the ears off a little :)

But yes you're right, it is a problem. If you mounted them as far back as possible it may work, but I didn't and it didn't without help from the cutoff wheel. 

stuart in mn
stuart in mn MegaDork
4/24/19 1:01 p.m.

There's not much to the hinges on an e28, they're pretty simple...I think you'd only save a couple pounds, so it's not worth the effort.

Speaking of the hood, the hot tip for e28s is to replace the support struts with a pair from an e23 7 series or an e24 6 series.  They fit right on but hold the hood up much higher, giving you more room to work.  https://www.amazon.com/gp/product/B00RUUFABW/ref=oh_aui_search_detailpage?ie=UTF8&psc=1&tag=pda0fc-20

AWSX1686
AWSX1686 SuperDork
4/24/19 1:29 p.m.
ross2004 said:
AWSX1686 said:

 The corners closest to the windshield stick out into points, so the stock hinges tilt the hood, but also move it forward and up so that those point clear. 

It's a Lemons car, you just cut the ears off a little :)

But yes you're right, it is a problem. If you mounted them as far back as possible it may work, but I didn't and it didn't without help from the cutoff wheel. 

Ahhh, just cut the ears off. Not as pretty, but certainly an option. It's no show car.

AWSX1686
AWSX1686 SuperDork
4/24/19 1:30 p.m.
stuart in mn said:

There's not much to the hinges on an e28, they're pretty simple...I think you'd only save a couple pounds, so it's not worth the effort.

Speaking of the hood, the hot tip for e28s is to replace the support struts with a pair from an e23 7 series or an e24 6 series.  They fit right on but hold the hood up much higher, giving you more room to work.  https://www.amazon.com/gp/product/B00RUUFABW/ref=oh_aui_search_detailpage?ie=UTF8&psc=1&tag=pda0fc-20

It's mostly due to the fact that they were trashed and unusable. Good tip on the hood struts though.

AWSX1686
AWSX1686 SuperDork
4/24/19 1:30 p.m.
MadScientistMatt said:

Frenchyd makes a good point: A hingeless lift off hood makes a lot more sense with a lightweight composite hood than a piece of steel.

I've also heard of lazy hood making by using the stock hood as a mold, just laying down the fiberglass on top of it. Finish isn't as good, but it takes less time.

Fiberglass hood and other body panels may come later for sure.

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