Less weight = Faster, and I'm still working on a weight loss program for my 1977 911s. This car is 95% for track use, so quiet comfort is not a priority.

Right now, I'm at 2440 pounds with a full tank of gas. I got it to this point with the following: Sunroof sheetmetal replaced with carbon fiber, turbo body with fiberglass front and rear RSR bumbers, fiberglass front fenders, fiberglass driver door, stripped interior (carpeted in rear), rs door panels, SSI exchangers and sport muffler. My car also has fiberglass RS america wing, "big red" twin turbo brakes, TRG Sways, Weltmeister STB, complete custom roll cage, and 17" fikse wheels with 255 and 275 rubber (vs 15" fuchs wheels stock), and 3.2 carrera engine.

Some things that I can still do that will further lighen my car are: Fiberglass/CF hood, Lexan, fiberglass passenger door, fiberglass/CF decklid/wing, remove undercoating/interior coating in front passenger compartment. This would all add up to maybe 100 lbs for a $few grand.

I am trying to avoid these due to cost, but will likely do most of them eventually. I have a couple of ideas to further lighten my 1977 911s, and dont know if they are worth pursuing.

1. Hollow out the dash area and leave only the guages in a custom mount, and dash top.

2. Remove sheet metal where rear seats used to be and replace with removable lexan or aluminum.

I've seen and heard of cars with these modifications, but I can't find any info on the extent of potential weight loss.

Does anyone have an idea of what kind of weight loss these mods might yield, and any possible complications that might be encountered with these undertakings.

Any help or input is greatly appreciated. Any other ideas that I have not already mentioned for further lightening my car are welcome too.

Thanks,

Jason French
1977 911s

 

I posted this topic in the "911 forum" too, as there seems to be much less activity in this forum, and I want as much input as possible.

Reply here or there, any input is appreciated.

Thanks,
Jason French

 

Jason, I've got a 77 911 too and have a lot more weight out than have you. I looked for those items that no longer added value to the purpose of the car - converstion to a strictly a non-road use race car.

From where you are now, consider the wiring harness as with the age of your car, what remains of the original is suspect anyway. But before you pull that out, you need to consider if this is ever going to be used on the street as all you really need are brake lights, starter, wiper and fuel pump (plus your ignition system) as a race car and that needs to be conveniently fused - in the cockpit. So, that is both an improvement and a serious weight reduction. While you're at it when wiring the brake lights consider making both the turn and current brake light as a single brake light - you want those wacko's behind to see your brakes.

You mentioned removing the sunroof pannel but didn't make it clear if you removed all of the hardware - consider that too - or even better, remoive the whole roof sheetmetal and replace with a carbon pannel as this gets more weight out of a high area and gives you the abiltiy to reinforce the cage properly and to complete the welding.

If you have an enclosed trailer, consider removing all of the glass and replace with lexan using the comercially available fiberglass frame on the
rear glass only - doing a 'flush-mount' (where you may have to reimforce the 'glass' as it will deflect at speed. The side 1/4 glass can be easily replaced by your local glass shop with lexan and remounted with or without the factory latches with no difference in weight. Of course, you need no glass in the passenger or drivers doors assuming you're using the "NASCAR" style doors that will accomodate door bars - another safety modification. For the front windscreen, I'd suggest buying your 'glass' from the supplier 'untrimmed', meaning that it's a bit oversized and can be mounted without the factory rubber using brackets welded into place, foam for protection and bolted through the lexan - selaing with black sealer for cosmetics. If you choose to go this way, I'd also suggest that you use flat black paint on the inside to 'trim' the outer portion hiding the brackets, foam and such - as done in a more sophisticated way on most production cars. If you choose, you can also paint your upper portion of the interior to give a bit of glare screen down 6 - 10" from the top - but remember, this is flat black paint - you can't see through this stuff - so choose thoughtfully.

Removing the seat brackets from both the driver and passenger sides offers a couple of benefits. First, the weight savings but you also now have a better palce to mount your battery (and can use a very small Sears DieHard lawn tractor battery), fire system, cool suit cooler etc. with a big plus of custom seat mounts moved closer to the center of the steering wheel and away from the door bars. If you feel good about this prospect, consider removing the existing tunnel, exposing the clutch and throtle cable and brake lines - and I assume you pitched the hand brake long ago - as this now gives you the opportunity to reinforce the seat to the side frame and longitudinally if needed depending on your fabrication of the seat bracket. If you feel comfortable with this, you could consider moving the shift linkage mount to a place where you can actually shift to fifth comfortably - rearward by a few inches - depending on your seat positioning - which requires cutting and rebending the shift rod.

There's not much gain in weight in the dash pad but those extra gauges belong in a garage sale - including the glove box door and interior. All of the plumbing for the defroster / AC and such is not of value anymore either.

The access pannel to the AC makes a good item for removal as this is the perfect spot for your oil tank. The fuel tank is a safety item and needs to go being replaced with a proper fuel cell mounted in about the same place
using longitudinal bars of square tubing that doubles as tub reinforcements. Mount the cell to those bars - not the chassis.

Choose your tow hook placement assuring that it's done with sufficient care to be of use when the inevitable tow truck driver gives you a tug from the gravel trap. Then remove all of the extra reinforcements done by the factory and replace with proper cage material remembering you front oil cooler, ducting and bumper mounting can use the same material for mounting points.

Finally, use your trusty cut off wheel and remove all of those wire mounts, welded bolts, brackets and anything that doesn't add function to the use, care and feeding of a race car.

 

Anyone have any experience with Lexan? I would like to switch out the glass in my Targa top for Lexan but have never worked with it before. How easy does it scratch? Anyone recommend a particular brand? Are there any sources of pre-cut Lexan for Porsche's???

 

Have you taken a look here?

Sherwood Lee
http://members.rennlist.org/911pcars

 

Remember that speed isn't everything, once you start removing components from your car it will mor ethan likely throw off the front to rear weight ratio which will in turn change the handling.. After making major changes it might be a good idea to get your car weighed and check the ratios before taking a corner at high speed.

Just a thought..

 

I have my car weight balanced after every major change, so no worries there.

The weight balance is one of the reasons I have only done the driver door in fiberglass, and kept the steel hood.

Oh yeah, and speed is everything! Thats what its all about, straight line, braking, cornering. Keeping a well balanced car is a top priority, because without it, speed is difficult to sustain in corners and on hard braking.

A couple of things I am considering doing in the short term are lexan rear window, and remove the heater blower from the engine compartment. (and of course, follow up with a subsequent corner weight balance)

Thanks for the replies, lots of good ideas!

Jason French
1977 911S 3.2

 

glass ---> Lexan

kill bumpers & bumper shocks

lightest brakes & rotors you can stand

tail lights are unusually havy (10+ lbs) and are way out on the end of the tail -- get the R type CF parts

do you have the Carera Al crossbar in front?

 

Take the glass of the front of the gauges!

 

toss all your guages, get a wheel mounted lcd. for speed and rpm, use flashing idiot lights and buzzers for everything else.

 

I did a few things you didn't mention. For what it's worth you might want to check them out. I've got an earlier car (1970) with two batteries. I replaced both of them with a battery that Elephant Racing carries. It's called an Odyessy. I think it's around 700 amps, and weighs around 14lbs. In addition to the weight savings, it is a dry cell which means you can mount it on it's side and it will never leak! Really a great product and costs around the same price as an optima of the same rating. I also went with hollow Torsion bars. They are a little bigger diameter than a solid bar of the same specs but still provide a substantial weight savings. I also used a hot air gun and a paint scraper to remove the sound deadening insullation "Goo" off the cockpit floor and lower side panels. If you use a heat gun, the stuff is pretty easy (Still a tedious and messy job) to pull up.
Future plans include removing the dash panel and the sheet metal, wires,defroster vents, motorized fans and ventillation controls. I will be replacing that stuff and excess instruments. I'll be replacing them with a carbonfiber dash from Getty designs and some carefully placed 2" diameter steel tubing to re-capture the structural value of the sheet metal I'll be removing.

 

Driving naked will save around 5 pounds, it sounds like that's about the only thing left other than the frame :-)

 

i hear the transmission weighs a great deal. have you thought of that?? or how about the hood, fenders, and doors.

I do like MD951's comment too.....I have seen that done here in texas too BTW and it's not pretty, unless it's a hot chick (but it never is...DAMN)

 

"...Really a great product and costs around the same price as an optima of the same rating."

Comparing the Oddysey (sp) and Optima in terms of weight is no contest. The Optima is certainly not a lightweight at around 35 lbs. However, if you compare CCA specs, they are not the same (all other battery rating schemes are not a true indicator of worst-case operation). Your choice may depend on vehicle use, your cranking climate and how much value you place on weight vs reserve capacity.

Sherwood

 

I managed to get my 930S down to 850kg racing weight with 55% weight over the rear wheels. It is easy to lose the weight out of the front but to get the rear is the hard part.

Watch the Odysey batterys - we had some failures where the terminals seperated from the plates internally in the battery. The ones made for jet skis seem to be reliable though. You can use insulated aluminium rod for the battery cables and fuel lines etc.

If making parts out of carbon fibre or fiberglass is a not an option, alot of items can be drilled of cut to lighten ie taillights and then resealed with aluminium tape (from airconditioning shops etc).

I wouldn't cut away the rear seat sheet metal again - the weight loss isnt worth the effort - I am about to weld a section back in one of my cars just so it doesn't leak anymore...

An easy way to balance the car is to move the engine and gearbox. I cut 2 inches off the G50 bellhousing to move the engine and box 3 inches forward and 2 inches down. The motor can only go far enough forward that the number 3 intake runner hits the shock tie rail, and you can just get a twin plate clutch in the bellhousing...

Some people think I am excessive compulsive - the next stage is to start drilling gears... I need a life...