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-   -   Weight distribution (https://www.rx7club.com/1st-generation-specific-1979-1985-18/weight-distribution-348374/)

grantmac 09-14-04 06:16 PM

Weight distribution
 
Alright heres the deal, I want to take as much weight from the front of my GSL and still keep street drivability. I'd also like to remove as much of it from the drivers side. I have a few ideas listed below and I'm looking for input:

1) Relocate battery to behind passenger seat with sealed box.
2) Go with either fixed lights, mechanical lifters for the stock ones and as much lightening of stock components possible or some other lighter set-up (fibreglass covers?)
3) Remove supports from underside of stock hood and use hood-pins (which I hate the looks of, too ricy).
4) Not sure how much the bumper weighs, would be worth lightening?
5) Cut holes in shit ;)

But seriously this car is my daily driver for the time being, that said my commute is short enough that I really don't need very many amenities. Don't have a stereo or A/C currently, rarely drive more than an hour. The commute is also through the city so I don't mind not having those things, stereos are dangerously distracting I find, especially considering the quality of the other drivers here. I'm actually thinking of making a fully removable stereo set-up using an MP3 player and computer speakers, I don't care about volume or base just be nice to have something to listen to other than the rotary drone on a long trip.
Grant
Grant

AdrenalifeRX7 09-14-04 06:29 PM

Don't cut holes in anything.

lemonade 09-14-04 06:38 PM

take the AC out....

AdrenalifeRX7 09-14-04 06:43 PM


Originally Posted by grantmac
Don't have a stereo or A/C currently,


he doesn't

grantmac 09-14-04 07:09 PM

The cut holes comment was a joke! I'm not into violating structural integrity just for a few less pounds. Serious about all the other comments. Oh and taking out the AC was one of the best things I ever did, I live in a very temperate climate so it wasn't a problem. It did how ever free up a lot of cooling to the rad, my car rarely ever needs to use the electric fan even when I'm in traffic and it's 85+ degrees out.
Grant

P.S. Think I'm going to do the battery relocation thing soon, along with some very beefy grounds.

Kweasi 09-14-04 07:48 PM

The battery relocation is a pretty good idea but make sure to use a sealed box, spillproof battery and GOOD HOLD DOWNS!!!

A buddy of mine is a scutineer and once saw a driver get beat all to hell when he rolled and the battery broke loose inside the cab; it swung around at the end of it's cables like a mace and beat the living sh1t out of the poor guy. It's kind of a funny image- but not much fun I'm sure.

-Kwe

Rx7carl 09-14-04 08:10 PM

Go with an FC water pump housing. Saves a few pounds.

cdrad51 09-14-04 08:15 PM

Doesn't that one protrude too much though?

kleinke 09-14-04 08:16 PM

You can save perhaps 10 lbs additional with an all fibreglass Hood. The Bumper can be replaced with your own design and yet retaining the functional utility and original cover, in that effort you will achieve another 10 lbs reduction.

Stevan 09-14-04 08:33 PM


Originally Posted by Rx7carl
Go with an FC water pump housing. Saves a few pounds.


This bolts to a 12a?
Is it aluminium?
And, what cdrad51 asked?

I have a replacement battery for a miata, it's an absorbed glass mat.
It's about half the size and weight of a regular battery, and it turns the motor, like a battery should.

K-Tune 09-14-04 08:41 PM

i've done all the things you listed. also removed the bracing from the front nose piece, fender braces, inner fender linings etc.

i should go get my car weighed sometime...

lemonade 09-14-04 09:01 PM

....my car weighs 2300lbs

NewRXr 09-14-04 09:27 PM

What about an aluminum flywheel and a lexan windshield? There's two big chucks of wieght that would be easyer than half the other stuff you mentioned. By the way I've done the battery relocation to my GSL-SE and it works wonders. Is there an aluminum radiator for our cars? Has anyone invented a replacement headlamp with a plastic lense, that would be a cool 5 pounds for a few minutes work?

Vernon

Rx7carl 09-14-04 09:45 PM


Originally Posted by NewRXr
What about an aluminum flywheel and a lexan windshield? There's two big chucks of wieght that would be easyer than half the other stuff you mentioned. By the way I've done the battery relocation to my GSL-SE and it works wonders. Is there an aluminum radiator for our cars? Has anyone invented a replacement headlamp with a plastic lense, that would be a cool 5 pounds for a few minutes work?

Vernon


Lexan is bad for a streetcar, not to mention illegal. Al FW isint front weight per se, but a different type of weight reduction (rotating mass). ;) No there isint an alum rad for our cars, but Im workin on some ideas. :D I hope to have something soon.

Elysian 09-14-04 09:53 PM

take off ur fenders and hood and call it good... itd look uber mad tyte yo...




j/k

grantmac 09-15-04 12:07 AM

Hmm, fender linings eh? They weigh much? I'm probably going to go with removing the bracing from under the hood too. I dunno how having no fender linings would hold up to our gravel roads and rain though. My car as it sits with virtually an empty tank and nothing in it weighs 2200 on the nose, I'd really like to get that figure below 2100 with most of it from the front if possible.
Grant

cosmicbang 09-15-04 01:07 AM

Keep the stock fenders but replace the hood. Fibreglass fenders are heavy, whereas a fibreglass hood is only about 8 lbs.

There is the Mazda factory race aluminum radiator, and a few others. I have several various ones but never weighed them. They are typically larger size which offsets the weight advantage.

cosmicbang 09-15-04 10:50 AM

radiators
 

Originally Posted by Rx7carl
No there isint an alum rad for our cars, but Im workin on some ideas. :D I hope to have something soon.

At first I thought you were crazy, but in fact the RB web site has a price for part number 11487 (Mazda factory race aluminum radiator) but no product description. They can probably be found elsewhere. Other than the factory race alum. rad, the 1962 Corvette aluminum plate type radiator used to be preferred (DeWitts Restorations makes them). You can get aluminum radiators in any size or shape from numerous sources such as Ron Davis, Griffin, and many other smaller vendors. (Fluidyne's web site says they only have 86-95 RX-7 and up and won't do customs. Still a possibility nevertheless.) I suggest Ron Davis--good price and reputation and no epoxy.

NewRXr 09-15-04 07:00 PM


Originally Posted by Rx7carl
Lexan is bad for a streetcar, not to mention illegal. Al FW isint front weight per se, but a different type of weight reduction (rotating mass). ;)

What's so bad about Lexan in a street car? It can be scratched so you have to treat it like paint, other that that it's completely transparent, keeps the wind out, and wieghs a lot less than glass. Where's the bad part? Anyways removing emmission controls is more illegal than plastic windshields ever will be and nobody worries about that $100,000 fine. Windscreen wieght reduction has the greastest effect on lowering the center of gravity you can make.

Now on the flywheel, just how much weight will be removed off of the front axle if one was to replace an 25 lb. flywheel with say a 12 lb. one? I would bet it would be about as much as 20 hood hinges. This would also be much safer than removing 2 hood hinges on a street car, what would you do if you had an engine compartment fire or a starter that stuck on? Lift your hood off and set it down in the ditch? Good luck with that route of wieght reduction. Also the flywheel will increase performance far beyond the same amount off static wieght reduction.

Even though both of these components aren't located fore of the front axle the potential drop in wieght is so great that short of relocating your battery or setting the engine back you'd be hard pressed to duplicate the weight reduction on the front axle by other means. A fiberglass hood is about it until Carl lets loose a lite wieght radiator.

Both of these ideas were good ones, I like Carl as much as anyone but I don't like naysaying without good reasoning.

Vernon

RXDad 09-15-04 07:10 PM

go on a diet

ch0g0nda 09-15-04 08:16 PM

Drive naked.

grantmac 09-15-04 11:22 PM


Originally Posted by ch0g0nda
Drive naked.

Done!, but seriously I'm starting to wonder what else there is. I've already done a lot of stuff, the battery is definately next, sealed boxes are just kinda hard to get for anything less than way too much around here. Maybe my EFI system will end-up lighter than the carb, who knows.
Grant

f/p79 09-15-04 11:30 PM

If "protection" provided by the front bumper isn't a huge concern, you can shed a lot of weight there. Remove the plastic cap and you'll find a lot of weight can be removed with a grinder type tool.

Rx7carl 09-16-04 07:58 AM


Originally Posted by cosmicbang
At first I thought you were crazy, but in fact the RB web site has a price for part number 11487 (Mazda factory race aluminum radiator) but no product description. They can probably be found elsewhere. Other than the factory race alum. rad, the 1962 Corvette aluminum plate type radiator used to be preferred (DeWitts Restorations makes them). You can get aluminum radiators in any size or shape from numerous sources such as Ron Davis, Griffin, and many other smaller vendors. (Fluidyne's web site says they only have 86-95 RX-7 and up and won't do customs. Still a possibility nevertheless.) I suggest Ron Davis--good price and reputation and no epoxy.


Well I didnt mention the MFR unit as its out of reach for most people. BTW, I found out that Ron Davis makes the MRF rads. :bigthumb:

Rx7carl 09-16-04 08:06 AM


Originally Posted by NewRXr
What's so bad about Lexan in a street car? It can be scratched so you have to treat it like paint, other that that it's completely transparent, keeps the wind out, and wieghs a lot less than glass. Where's the bad part? Anyways removing emmission controls is more illegal than plastic windshields ever will be and nobody worries about that $100,000 fine. Windscreen wieght reduction has the greastest effect on lowering the center of gravity you can make.

Now on the flywheel, just how much weight will be removed off of the front axle if one was to replace an 25 lb. flywheel with say a 12 lb. one? I would bet it would be about as much as 20 hood hinges. This would also be much safer than removing 2 hood hinges on a street car, what would you do if you had an engine compartment fire or a starter that stuck on? Lift your hood off and set it down in the ditch? Good luck with that route of wieght reduction. Also the flywheel will increase performance far beyond the same amount off static wieght reduction.

Even though both of these components aren't located fore of the front axle the potential drop in wieght is so great that short of relocating your battery or setting the engine back you'd be hard pressed to duplicate the weight reduction on the front axle by other means. A fiberglass hood is about it until Carl lets loose a lite wieght radiator.

Both of these ideas were good ones, I like Carl as much as anyone but I don't like naysaying without good reasoning.

Vernon

Dont sweat it, no offense taken. Im always interested in different points of view. Im no expert, just an avid student.


My take on a lexan windscreen. The compound curves will be difficult to replicate. Also the windloads at speed may cause it to bow in and maybe end up in your lap unless you use straps/braces. :eek: Lastly, it will scratch up quickly from the windsheild wipers and abrasion from dirt/sand/crap hittting it head on.


No disagreement on the FW. I was just pointing out that its not going to show up significantly on the scales (front weight wise).


I want a hood with stock hinges and latch fittings. Just a lightweight one.

Feds 09-16-04 09:06 AM

Keep in mind that the weight advantages of an aluminum rad will be negated if the rad is higher volume. Water is wicked heavy.

The bumper is a good place to start, then FG hood and sail panel (between the lights) Fixed lights will be lighter than pop-ups, otherwise, I can't think of too much unless you want to unwrap the harness and take out unneccessary wires.

Rx7carl 09-16-04 09:54 AM


Originally Posted by Feds
Keep in mind that the weight advantages of an aluminum rad will be negated if the rad is higher volume. Water is wicked heavy.

The bumper is a good place to start, then FG hood and sail panel (between the lights) Fixed lights will be lighter than pop-ups, otherwise, I can't think of too much unless you want to unwrap the harness and take out unneccessary wires.


Good point. 8lbs per gal.

Feds 09-16-04 10:08 AM

No, 1 kg per litre.

Manntis 09-16-04 11:46 AM


Originally Posted by Feds
The bumper is a good place to start, then FG hood and sail panel (between the lights) Fixed lights will be lighter than pop-ups

The header panel between the lights is actually quite light. Replicating it in fibreglass is difficult because it has metal structure running all the way down to the bottom of the Radiator

cosmicbang 09-16-04 12:55 PM


Originally Posted by f/p79
If "protection" provided by the front bumper isn't a huge concern, you can shed a lot of weight there. Remove the plastic cap and you'll find a lot of weight can be removed with a grinder type tool.

Wow, that would be a lot of grinding!! I would just remove the entire bumper and make a very simple lightweight aluminum frame to hold the cover and lights in place. The bumper shocks themselves can be removed at the same time since they are fairly heavy and would no longer serve any purpose.


Originally Posted by Rx7carl
Well I didnt mention the MFR unit as its out of reach for most people. BTW, I found out that Ron Davis makes the MRF rads. :bigthumb:

You are correct. My older MFR aluminum radiators look somewhat different. The Ron Davis/AWR/MFR aluminum radiators are $471 for the tall, and $445 for the short from AWR, which is a reasonable range for an aluminum radiator (they cost even more back then). It would not make sense to save a few dollars with a cheap one considering the consequences of overheating the engine.

Feds 09-16-04 01:15 PM

Canadian GSL eh?

Have you ditched your headlight washers?

Also, things like sub zero fluid and hot start assist may be worth tossing.

What is the status of your interior? you can pull the carpet, take out the sound deadening, then put the carpet back down.

grantmac 09-16-04 08:34 PM

Hmm, headlight washer container is empty and coming out as soon as I can find all the bolts that connect it. Possibly even take out the nozzles for it. The sub-zero tank and hot-start are both gone, along with all the emissions. I've got nothing in the car for interior except the dash and two sparco sprint seats (those babies are super light!). I also intend on adding a front strut bar and sway-bar, which sort of adds weight in the wrong area.
Would it be feasable to relocated the battery all the way to the back of the hatch area? I don't have any storage bins so I can pretty much mount it anywhere, the only advantage I can see with mounting it where the bins were is that it's gonna be lower down and so lower the CG a little bit.
Grant

kennetht638 09-17-04 05:29 AM


Originally Posted by grantmac
3) Remove supports from underside of stock hood and use hood-pins (which I hate the looks of, too ricy).

You may be in luck because I don't believe you would need hood pins to hold down a forward-opening hood unless you're removing the stock latch too, or you're going racing in reverse (and have a really tall reverse gear). You should be careful with removing hood bracing though, because at least some of it is there for a reason, and you probably don't want your hood buckling at high speeds.


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