Weight Reduction Ideas, Please!

[spdracr0]

A true racer would never worry about his exhaust rusting over a performance advantage.....remember exhaust can be replaced later, wins are forever..

 

[roadhard1960]

The factory roll over protection might work fairly well at moderate speeds. Do you race at moderate speeds? I rolled into a telephone pole at moderate speeds in my Rabbit. Real Rabbit 1980. Merely luck that I did not break my neck. A roll cage that had vertical posts at the A and B pillars with horizontals up high might have reduced my pain in the neck. Moderate means I started spinning out at less than top speed third gear which I guess was less than 70. I scruffed off some speed as I was spinning back and forth before I impacted. No recollection of the last second before actually rolling and impacting. I do remember the "oh sh.. you did it now" comment I made. Granted the newer Jettas are safer than that Rabbit but still just about no one who crashes says "darn, I wish I had not installed a good roll cage." Cost of cage less expensive than death. Not that a cage prevents death. If you were really worried about your kids you would stop skydiving, right?

I am all for better attachments for Hans device and race harnesses.

 

[spdracr0]

Do not run a skid plate of any kind, if teh motor is puking something out you will want to know it right away..If it gets a head gasket and pushes water (especially under boost) you would know it in a straight not after it puddles on the plate/cover and dumps it under a rear as you in the apex of a turn,,,people behind you may appreciate it too...

 

[spdracr0]

If wearing a Hans and in a 5 point harness the car best have a cage causu you have no option but to be sitting perfectly upright...even if you anticipate the car is going to roll , you have no way of lowering your head.

 

[spdracr0]

A properly constructed moly cage negates the need for crash beacing as teh cage is your crash beacing....probably a wash as weight goes though

 

[IndigoBlueWagon]

I looked at seats this morning, and I'm fortunate in that I fit both in the Recaro Pole Position and the Profil. I'm leaning towards the Profil, in part because it's more comfortable and I can get a matching passenger seat in their XL configuration that will accommodate larger check riders. The regular seat is a snug fit for my 34" waist, which, with persistence, will be 32" by racing season. But still the regular seat is a good fit for harnesses and a hans device. I also looked at harnesses and steering wheels.

I'm going to get a subframe from Chill and attempt to mount the MKII steering rack on it. I can compare it to a stock rack he has to make sure I can match up tie rod ends and attachments, as well as the steering column attachment.

 

[2004STARWARSTDI]

Weight reduction

Remove muffler

 

[DbLog]

Which flywheel are you running?

 

[M I N I O N]

Here is my list for this year to help you out:

* removed sunroof and add carbon block off
* cut out the spare tire well and replace with carbon sheet
* custom 6-ply carbon hood with no frame
* custom 6-ply carbon hatch with no frame
* custom carbon front bumper support
* Bride lowmax one piece fiberglass bucket seats
* lexan side and rear windows
* hole and dimple die interior structure supports
* delete a/c and heater box, replace with an electric heater only
* light fat wheels in the front and street skinnies in the rear

Making carbon pieces for yourself is easy but time consuming. The materials cost about as much as buying an off the shelf piece but it is all carbon fiber, not just fiberglass with a single cosmetic layer of carbon. Epect the pieces to weigh a little less than half of an off the shelf piece. If my hatch and hood work out well, I will do the front fenders, rear quarters, roof and doors next year to further it.

I know this id TDIclub, but if you are racing in a class where you don't have to have a TDI motor, I would also recomend swapping in something bigger/badder than the diesel. Even with a GT35r, my VR6 will hit maximum boost (20psi) within a quarter of a second of getting in gear when shifting from redline.

Might I also recomend a drag clutch. I am using a clutchnet stage 5 with an unsprung race disc. It shakes the car engaging from 1st on the street a little but it feels great and isn't too harsh. You can feel the difference coming out of a shift.

 

[M I N I O N]

I forgot to add one details. After about where the cat normalls goes, my 4" exhaust is getting remade out of aluminum. Instead of welding, the exhaust will dissipate more heat and make the gasses more dense the further they get down creating a siphon effect and improving spool times. It also naturally weighs a tenth as much.

If you have luck mounting the mk2 steering rack, pleeeaaaaase give me details. I've been wanting to try this for weeks. It looks more than possibly but I have been afraid you will need an MK2 steering column or a custom lower linkage which would be difficult to get to line up.

You also may have good luck with a spool diff if you never street the car. Be careful as to put much higher rated axles on or you will hit the wall should one break.

 

[LurkerMike]

I forgot to add one details. After about where the cat normalls goes, my 4" exhaust is getting remade out of aluminum. Instead of welding, the exhaust will dissipate more heat and make the gasses more dense the further they get down creating a siphon effect and improving spool times.

To a point, yes. But here is the kicker... as you create the expansion chamber effect, if you slow and/or cool the exhaust stream flow beyond critical point, you create a high pressure pocket that acts as a restriction in the pipe... like a blockage that causes additional backpressure to build for the exhaust stream to push it out of the pipe. The critical point varies according to the heat, velocity and volume of the exhaust stream as well as the change in size and shape of the pipe.

It also naturally weighs a tenth as much.

You mean about 1/3 as much...

What wall thickness are you going to run in 4"?

From previous posts I made in this thread:

How to calculate the weight per foot of exhaust tubing:

Stainless : (lbs./ft) = 10.68 W(OD - W)​

Aluminum: (lbs./ft) = 3.6904W(OD-W)

OD = outside diameter , W = wall thickness

304 Stainless
4" dia. .060" wall, 2.6 pounds per foot, 8 feet = 20.2 pounds
3" dia. .060" wall, 1.9 pounds per foot, 8 feet = 15.1 pounds
3" dia. .048" wall, 1.5 pounds per foot, 8 feet = 12.1 pounds
2.5" dia. .060" wall, 1.6 pounds per foot, 8 feet = 12.5 pounds
2.5" dia. .048" wall, 1.3 pounds per foot, 8 feet = 10.1 pounds

6061 Aluminum
4" dia. .060" wall, .87 pounds per foot, 8 feet = 7 pounds
3" dia. .060" wall, .65 pounds per foot, 8 feet = 5.2 pounds

 

[IndigoBlueWagon]

MINION, thanks for the ideas. There was a VW motorsport carbon fiber hood on Vortex that weighed 6 lbs., but it was $900. Seats are more important to me right now. I'm going to have my fabricator make bumper supports out of aluminum which should go together quickly and weigh a lot less than the stock items. What does your car weigh?

And I know what you mean about the TDI. If I didn't sell stuff for these cars for a living I'd probably run a 1.8T with a K04 or some such. 300+ HP is a breeze.

DbLog, I'm going to run a SBC Stage 3 clutch with a 17 lb. single mass flywheel. Mostly because I know how a 14 lb. one drives and I want to see what the 17 lb. one is like. So that's 4 lbs.

Regarding power, I make 185 with IBW, but EGTs would be too high with the fueling level I have right now. I'm hoping that better intercooling will take out 100 degrees or so, and the 260 cam will take out another 100. If that's true I can have a reliable engine that will make good power all day and not get too hot.

MINION, I'll post here about the MKII steering rack. You've raised the concern I have, which is the attachment to the MKIV steering column.

 

[whitedog]

Instead of a full roll cage, how about a roll bar just behind the drivers seat with bracing to the rear? I certainly know nothing about this stuff, but it's just an idea that pooped into my head. Would this provide attachment points for the harness?

 

[IndigoBlueWagon]

I'm not doing a full cage, just the bar. The real reason, however, is that the cage is dangerous if you aren't wearing a helmet. And it's a safe bet that I don't want to wear a helmet when driving on the highway.

 

[roadhard1960]

You mean that a 5'2" driver is going to worry about a full cage? That would suggest you are at least 5'10". If you set the seat to full submarine which should be easy enough with a race seat don't you have clearance? I messed up my neck a bit when the roof collapsed in the Rabbit. No cage or bar. I would have to find a wreck picture to see if a bar would have helped. Just being a smart butt.

 

[M I N I O N]

I'm with you on the full cage. Don't go FULL unless you have to. It would only be worth it if you are within the 1/4 time bracket which requires it or if you are planning on hitting the twisties as well.

As far as the aluminum exhaust piping. I wasn't being literal when I said a tenth. The cooling effect of the aluminum also should not be near enough to create a high pressure spot anywhere in the pipe. There are people running aluminum exhaust already so I should be good. I have held a 4" aluminum exhaust system and it was deffinately in the no more than 10lbs. My 3" exhaust is very heavy so it is an improvement.

 

[IndigoBlueWagon]

A 2" DP weighs 15 lbs. The exhaust from the cat back weighs about 18 lbs. I know because we ship these all the time. The heaviest parts of the system are the CAT and the muffler.

No, I'm not 5'10", but in my street accident last year, wearing stock belts, I whacked my head against the windshield header hard enough to get a concussion. I hesitate to think about what would have happened if a 1.5" bar was in front of the header. And although wearing a 4 point harness is a definite help, I still would feel better without that steel there.

I will put in a roll bar, and I won't scrimp on its construction. But keep in mind that the rollover protection in a Rabbit is vastly different than a MKIV Golf. As I posted earlier, part of the appeal of the Golf is the strength of the structure.

 

[DbLog]

In a mkIV I agree just a roll bar would be safer on commutes. Roll bars should have come as an option from the factory on the Rabbit.

I rode in a Rabbit at Grattan. The thing scared the hell out of me. After a lap or two I got settled in but if it would have rolled the glorified tin foil of a shell wouldn't have done much good. My helmet would hit the roof on certain sections of the track. Heck the driver called me his balast. The thing probably would have flipped if my 150lbs wasn't weighing down the right side.

I will put in a roll bar, and I won't scrimp on its construction. But keep in mind that the rollover protection in a Rabbit is vastly different than a MKIV Golf. As I posted earlier, part of the appeal of the Golf is the strength of the structure.

 

[LurkerMike]

The thing probably would have flipped if my 150lbs wasn't weighing down the right side.

Sounds to me like you are ready for this:
http://www.youtube.com/watch?v=WzpLUxB9hdg&feature=PlayList&p=A2BC11474A4CF24E&playnext=1&index=81

 

[Got Bearings?]

Attack non-structural sheet metal on the inside with a hole saw, sawzall or jigsaw. You can remove a lot of non-structural sheet metal behind all the door panels.

Remove the entire dash and start removing stuff that you don't need.

 

[IndigoBlueWagon]

I checked the weight on the rear of a 2.5" exhaust we shipped last Friday--18lbs, and that's wrapped in bubble wrap and ready to roll. The DP weighs about 12 lbs. So the entire exhaust, less muffler or cat, is 30lbs. or less. Doesn't seem I'm going to save a lot off that 18lbs. that's the rear two sections. Oh, and that was a Jetta exhaust: the Golf's is several inches shorter.

Got Bearings, I've thought of taking out the heater core and associated stuff, but have been advised it doesn't weigh a lot (about 4 lbs) and is a ton of labor to get to. And then I don't have any heat or defrosting. Maybe as the next step to a pure track machine. I recall sitting at pit out at Lime Rock a 15 months ago when it was snowing. I had the heat on full blast, windows down per regulations, and was pretty comfortable. The poor guy behind me was in a gutted Neon and was numb. And there was also an Ariel Atom there that day and that driver quit. He lost all the feeling in his hands and feet, even with a driving suit and gloves.

 

[Got Bearings?]

Sounds like that "snow" stuff is cold.

If you have track days in the cold, then keeping the heater stuff is a good idea. Even if it's 10-20-30 lbs, the alternative is extreme discomfort or no track time. Not a good trade off in my opinion.

I mentioned removing the dash because you can always find something behind it to remove that you don't need. When you remove that stuff, you can then remove its wiring as far back as you can trace it. Wiring adds up quick. There might even be a brace behind the dash that you can remove.

Don't forget speed holes!

 

[nicklockard]

Sounds like that "snow" stuff is cold.

If you have track days in the cold, then keeping the heater stuff is a good idea. Even if it's 10-20-30 lbs, the alternative is extreme discomfort or no track time. Not a good trade off in my opinion.

I mentioned removing the dash because you can always find something behind it to remove that you don't need. When you remove that stuff, you can then remove its wiring as far back as you can trace it. Wiring adds up quick. There might even be a brace behind the dash that you can remove.

Don't forget speed holes!

After having gone through a heater core replacement in the near past with Mr. Oldpoopie, I can attest that the wiring harness'es behind the dash add up to about 30 lbs. But most of it is needed for heater controls, ABS, dash lighting, interior lighting, etc. Unless you want to make it a pure race car and delete most of those functions, you can't just go hacking away at them. Now if you had the time to do some precise surgical paring, maybe you could shave 10 lbs from here and there. Dunno.

Behind the dash, there really isn't any "extra" metal hanging around though. It's pretty frugal weight-wise, and you need that cross beam, unless you want to make an already overly-flexible unibody even more woggy than it is. It only weighs about 8 lbs anyhow. I don't think removing metal from doors is a hot idea unless you want your doors flexing, shimmying, vibrating, and breaking glass. <IMO only.

 

[shortysclimbin]

Wow sounds like you really have been pushed up a class Peter! I have been riding a bike almost every day after work this season and eating salad. best pounds lost but hardest to get too!

As far as the mk2 rack in a mk4 the rods will need to be cut and welded with extensions. You will also need to find a mk2 powered rack or mk3 one for the fittings to convert to the larger spline section. IIRC the mk4 unit is longer than the mk2 so you will need an extension welded in it to work.

Harness wise there is only one brand out there DOT legal FYI! and they are 4 point. I have them in my car and love them. Pad your bars around your head and side just for added safety. Remove the rear bumper insides and just put on the plastic shell, you will have a lot of metal in between you and a rear end crash. The front bumper can be lightened a little but is structural to the frame.

Change the rear end into independent rear... that will save a ton of weight and allow you to lower the ride height more. This would not be easy to do though...

make up a set of aluminum door cards this will save a little weight when you remove all the foam and plastic that comes with it and replace the handle with rope.

On the mk2 in europe they sell rear window panels that are metal. IIRC they are lighter than the glass and I may go with them to save some weight down the road. maybe you could a similar set for the golf?


Water, Fuel weight is around 8pnds a gallon! cut your coolant system down and fuel to the minimal! A nice thing with the tdi is that at 35mpg tracking you should be way ahead of the next guy in fuel weight... I should show you my nice new fuel cans...

Also, do they have tules on fuel for alternatives? Biodiesel doesn't burn for beans.... I am planning on seeing if I can run a smaller cell in cabin since the fuel is considered non harardus

 

[IndigoBlueWagon]

Thanks for the tips. I'm at least twice your age so the pounds come off that much more slowly. However, I've done this before so I can do it again.

Interesting tips on the steering rack. I ordered a MKII new TRW rack today, short money. I'm excited to compare it to the MKIV, and I can harvest whataever I need from the rack coming out of the car.

I'm not swapping out glass yet. And what do you mean about the front bumper brace being structural? If that's true I'll change my approach. I could cut the brace off outside the points where it bolts to the frame rails.

Regarding class, I think I'd be in SCCA Street Modified. I'm in what my club calls Street Prepared, and not competitive there (modified STIs and Evos are the competition). They let me run in a group where I am competitive, and it's a kick.

PS: You have a PM.

 

[GuyGuy]

I know this is small stuff but you could also remove the three glow plug coolant heater coming out the driver side of the head.

 

[whitedog]

I know this is small stuff but you could also remove the three glow plug coolant heater coming out the driver side of the head.

Actually could probably just install the coolant flange from an Automatic trans.

 

[GuyGuy]

Actually could probably just install the coolant flange from an Automatic trans.

good one!!

 

[IndigoBlueWagon]

This showed up today. It's from an MKII Golf.

I need to get it side-by-side with an A4 rack and see what I need to change. It seems to be 4 turns lock-to-lock. Not real quick. Guess I need a small wheel. I'm thinking this.

Sorry for the big picture. And I want something less slippery than leather for a finish.

 

[Farfromovin]

Actually could probably just install the coolant flange from an Automatic trans.

Hey, I need one of those!!!