Losing weight

[tynor]

The car's GCR weight is 2280 ('83 ITA RX7). I've never managed to weigh less than 2440. That's 160lbs overweight. I'm at wits end trying to find ways to bring the weight down.

Asking around, it seems none of the other class competitor are having a particular problem meeting minimum weight. In fact, one competitor weighs about 275 and has a cool suit cooler system and still manages to weigh in at minimum.

Yet, my car is 160lbs overweight.

I weigh about 190 and could conceivably lose about 10lbs. But I don't see where else to take weight off the car.

The interior is stripped. I don't have a cooler. My Panasports aren't particularly heavy. I have a 15gal fuel cell and I'm careful to run a minimum amount of fuel for any given race. I can't find anything else to take off the car.

My cage is overbuilt - it's built out of 2.0x0.080 tubing. As I calculate it, there's about 800 linear inches of tubing in the cage - so it weighs about 55lbs. Even if I replace that with lighter tubing, the lightest legal cage I can install will only save me 10-15 lbs... What else is there??

I don't have a NASCAR bar on the passenger door, so have a stock door with glass. How much could I expect to save by gutting the door?

What else??

(thanks for your help -- sure would like to get the car down closer to minimum weight so I can stop using that as an excuse for poor lap times )

Steve Tynor

[JeffYoung]

The car's GCR weight is 2280 ('83 ITA RX7). I've never managed to weigh less than 2440. That's 160lbs overweight. I'm at wits end trying to find ways to bring the weight down.

Asking around, it seems none of the other class competitor are having a particular problem meeting minimum weight. In fact, one competitor weighs about 275 and has a cool suit cooler system and still manages to weigh in at minimum.

Yet, my car is 160lbs overweight.

I weigh about 190 and could conceivably lose about 10lbs. But I don't see where else to take weight off the car.

The interior is stripped. I don't have a cooler. My Panasports aren't particularly heavy. I have a 15gal fuel cell and I'm careful to run a minimum amount of fuel for any given race. I can't find anything else to take off the car.

My cage is overbuilt - it's built out of 2.0x0.080 tubing. As I calculate it, there's about 800 linear inches of tubing in the cage - so it weighs about 55lbs. Even if I replace that with lighter tubing, the lightest legal cage I can install will only save me 10-15 lbs... What else is there??

I don't have a NASCAR bar on the passenger door, so have a stock door with glass. How much could I expect to save by gutting the door?

What else??

(thanks for your help -- sure would like to get the car down closer to minimum weight so I can stop using that as an excuse for poor lap times )

Steve Tynor

Calling Dick Patullo!

Dick did a strip to the bare chassis build on an ITA RX7 to try to make weight and he did. He posts here frequently and is on the CRB so his e-mail addy should be easy to find.

[tynor]

A good thread with weight saving ideas that didnt show up when I did my original search:

https://improvedtouring.com...ad.php?t=29963

Still having problems identifying 160lbs of remaining opportunities off that thread, but it does give some food for thought...

[dickita15]

Yes back in 2006 I was pretty sure you could not make weight in a rx7 and my shell was pretty beat up so I did a rotisserie build with intent of proving you could not make weight. Well I failed. I managed to make weight with a 240 pound driver, but it was a lot of work. You have to look at every part on the car and see if you can make it lighter legally.
I used a 79 shell which seem a little lighter but updated all the front sheet metal to late as the front bumper is lighter.
Are your Doors gutted? 18 pounds per door.
When I researched batteries I searched the Auto Palace sight for batteries for the car and found a 20 pound spread.
Susko had a sway bay design using a modified stock front bar that is 6 pound lighter than a 1 1/8th bar.
No rear bar.
Undercoating and sound deadening.
I use a 8 gallon cell but I can swap my 12 back in for longer races.
Are you using a panhard bar, the watts link bracket welded the frame looks pretty heavy to me.
All the parking brake brackets on the frame are gone.
Six pounds by legally trimming the wiring harness. Took 20 hours with the harness on the bench.
Aluminum Radiator.
No front strut bar, I do not believe they help
I have left some stuff on the table too. Exhaust could be lighter but I like quiet.
I still have old school gauges, I could go to a data system.
There is really no single magic bullet, and it is certainly easier if you are building a new shell, but it is looking at every part and seeing what you can do.

[tynor]

Thanks Dick.

From your list, it looks like there are possibilities in my passenger door (no NASCAR bar, so not gutted), the battery and radiator and perhaps a smaller fuel cell. Most of the rest I've already done (I'm using a panhard rod). Sound deadening is already gone, but it looks like the undercoating was never removed. (google suggests that may only be worth 4-5 lbs though?)

[spawpoet]

Panasports generally aren't all that light compared to some other wheels out there. You could have up to 20 lbs to lose here depending on how much you want to spend on wheels.

[Ron Earp]

Jeff, Dick, and other have pointed out what you have to do. And, having done the same thing on other cars, and most recently on my Mustangs(s), my advice is to do it yourself - do not take the internet as the final answer. There is good advice here, use it, but you won't know until you do the job yourself and use your scales to verify your weight loss.

On my recent build we:

*Lost 9 lbs of sound deadening I for sure thought was only around two lbs. Man it was a lot of work.

*Lost 11 lbs of wiring that I thought was only four or five, and, there is more to lose. This was more work than the scraping of deadening.

*Learned a bunch about the actual weight of wheels. This is a very trouble-prone area because of what folks will tell you, that the company that makes the wheels will tell you, and then there's reality.

And the list goes on.

You need to think in terms of ounces and pounds, not in terms of five or ten pounds. They'll add up to tens of pounds, and hundreds if you keep after it. It all depends on how much effort you want to put into it. There isn't an easy button for weight loss on a car. We've just been through WeightLoss1.0 on the stangs and WeightLoss2.0 will start late this year when racing season is over.

[tderonne]

Check you cage weight calcs. Google says 2"x.080 weighs 2 pounds per foot, giving you over 130 pounds of cage (in tubing alone)...

[seckerich]

2.00 X .083 is DOM size and weighs 1.699 #/ft

113.266 #

Smallest legal is 1.5 X .095 and is 1.426#/ft

95# same cage

[Flyinglizard]

Too much tubing and undercoating?

[joeg]

Appears a lot of things...Driver, gutting doors, tubing etc.

[seckerich]

Weigh a gallon of paint sometime and see how many layers you have.

[spawpoet]

Weigh a gallon of paint sometime and see how many layers you have.

I don't recommend doing that on a 40yo car though unless you plan on hitting the rotisserie. It can be really depressing. Especially when you start finding the bondo under and amongst the bazillion layers of paint.

[cbuczesk]

I don't recommend doing that on a 40yo car though unless you plan on hitting the rotisserie. It can be really depressing. Especially when you start finding the bondo under and amongst the bazillion layers of paint.

I did that this winter. What a project! I removed the sound deadener, undercoating, etc. I discovered 6 layers of primer/paint, a quarter panel welded over the original quarter panel and 1" of bondo filling the dent on that quarter.

Chuck