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Weight reduction tips.

26K views 53 replies 16 participants last post by  WBIRYUZQIRIQV12 
#1 · (Edited)
Hello.

What do you suggest to reduce weight on my car?

I'm looking for normal tips like if there are different hood, fenders, wheels, tires, trunk hatch, etc. makes, rating, sizes or model year differences in parts to replace.

Like, did the facelift hood, for example, come in different weight? What about other parts?

I replaced the tandem steering/hydraulic pump with a normal one. I hope that made a difference. Hmm... guess I can remove the hydraulic fluid reservoir too... that slipped my mind.

I'm also not looking for crazy ideas like ditching the spare tire or removing the rear and front passenger seats. I don't think me losing weight is practical too.

Also (and the reason why I didn't just go for it practically before asking), do you think it would make a worthy difference in acceleration and fuel economy? Let's says we manage to free ~40kg (hopefully), is it worth it?

By the way, I remember the hood in the W126 we had felt heavier than that of a 1998 W140's I once looked at. Is is possible they changed the material? If yes, could it be the same with pre- and facelifted W124's?

Purpose of thread:
Losing weight to improve acceleration and MPG. I weigh ~91kg, if you're interested (or if that's important).
 
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#4 ·
Hey, I found something interesting. 1 liter of gas weighs 976 grams. On 300E's like mine, this means a full tank of gas puts 61.32kg on the car. It could be a good idea to use as less gas as possible (like maybe a little more than a quarter full tank) on the track to have better chance of winning, specially if coupled with other weight reduction. Could also be not a bad idea to always keep the tank between quarter and half full when driving in city.



Step 1: get one of these.
Like these?



Good call. 40lbs looks like a good start.



Step 1: get one of these.
Look ma, I'm a lumberjack!
 
#7 ·
I have no idea what those are, btw.

Never mind me :D
 
#6 ·
Well ah... consider my goal getting rid of weight that turned out to be not necessary in the original design, of got revised after these ~25 years. I'm not really looking for out of the box fabrications or inventions. That wheel point earlier was a good tip, for example.

That W126 vs W140 hood weight difference was noticeable to me, and I don't think that part of the body makes a difference to the car in this difference.

But you do make an understandable point and following it seems like a logical course of action. What I'm asking for could be a real hassle.
 
#9 ·
Hmm... my taste does not disagree with them that much, so I guess it's okay. I'll see if they they are available here when it is time to replace mine. Two of mine were already machined and require careful adjustments to run fine at high speeds (+90mph).

Come to think of it, I've seen some cars come with weird and pathetic looking thin compact spare tires instead of the same size of the rest four. I wonder if there are tires like those for W124.
 
#12 ·
The engine. You forgot the engine.

I really don't see many options with the car itself aside from removing interior pieces. You could permanently close the sunroof and remove all the gear for that. You can remove any unused electronic things (factory amps, phone, etc.). But really, the wheels and tires are your best bet, because they reduce the unsprung weight and makes it easier for the drive train to turn them. So, you should get a little extra performance and mileage there, though I don't know that it would be noticeable anywhere but on a track. I think you would have to shed quite a lot of weight from the car body to get any significant gains.
From the replies so far, this seems to be the case alright; i.e. wheels wise.
 
#11 ·
I really don't see many options with the car itself aside from removing interior pieces. You could permanently close the sunroof and remove all the gear for that. You can remove any unused electronic things (factory amps, phone, etc.). But really, the wheels and tires are your best bet, because they reduce the unsprung weight and makes it easier for the drive train to turn them. So, you should get a little extra performance and mileage there, though I don't know that it would be noticeable anywhere but on a track. I think you would have to shed quite a lot of weight from the car body to get any significant gains.
 
#13 · (Edited)
My 95 E320 weighs around 3,600 lbs and it has 217 hp. Compared that to my former 2014 VW GLI manual at 3,200 lbs and 210 hp, it's not so bad. The turbocharged GLI would smoke it with a time of 6.9 sec vs 7.9 sec.

My point is there's nothing you could shave off weighting 400 lbs, apart from the engine, that would reduce that 1 sec difference in acceleration. Now, adding a turbocharger might help.

Yeah the stock Benz might be slower but it does take you there in timeless style and luxury.


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#14 ·
There is fuel economy too, but I guess even that can't be changed that much.

Yes, heavy-ness is there for a reason/compromise after all. There is always a fair trade, Fullmetal Alchemist-kun.
 
#19 ·
my 1989 GLi got about 30 MPG and I drove the pee out of it. FWD transverse engine has lower mechanical friction, resulting in higher efficiency. 1.8L 4 cyl motor has lower friction, higher E. 5 speed stick shift and smaller cross section body, all lowers friction/drag. I think the 89 jetta had about 2200 lbs curb weight, 3200 lbs gvwr, so it was a LOT lighter than the equiv year W124.
 
#28 · (Edited)
I know what you mean. Prior to the 2014 Jetta I just sold in order to make my E320 a daily driver, I had a 2000 Jetta S 2.slow 5 speed manual. Yup, the one with the agricultural 2.0 liter 8 valve engine pumping out 115 hp. But, that car was so much more fun to drive because it was tossable. It only weighted 2800 lbs, and the manual tranny was close ratio. At 5th gear it was screaming at 2,500 RPM going 55 MPH. And it still wanted to be pushed all the way to 5,000 RPM. It was a car you drove by planning ahead and keeping momentum.

The GLI was a lot faster, but the 6 sp manual was not made for street driving. The gap between 2nd and 3rd was too wide and going around a corner at 2nd gear lugs the engine. Plus, there's the dreaded upshift rev hang that the ECU and electronic accelerator partner up to sour the driving experience. No such rev hang was exhibited by my former MK4 Jetta as it had direct cable linkage to the throttle. Revs just drop when you let go of the accelerator.

That's part of the reason I'm giving up on modern manual transmission with my E320's slushbox. Gone are the days of direct throttle linkage and predictable clutch bite points. One thing I like about the W124's 4 speed auto is the gears are close. I can still get the car to cruise at 55 at around 2,200 RPM. It's a momentum cruiser with power to back it up using the kickdown switch.







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#21 ·
I just answered my own question. A stock W201 190E 2.6 weighted around 2,866 lbs vs a stripped down DTM version at around 2,400 lbs.

LCG, you're right! You can reduce the weight of a W124 down by 400 lbs if you took out those things you mentioned.


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#22 ·
Unlike most world wide local dealers I know of, German import W124's come in many trims, including custom chosen options. Mine is of the latter. It actually does not have electronic front seats. That must reduce the weight a little. I also think it does not have an engine oil cooler.

Fun fact:
I once saw a W140 with manual front seats here. Yes, it was a German import.
 
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#25 ·
Since you seems to be seriously thinking about getting better acceleration out of your car with weight reduction, it would actually be interesting to know how much in real life you will gain if you do all the things that have been mentioned.

Do a baseline run in stock trim and another one once you have completed the disassembly. I'm sure there are some people who would be interested in knowing how much they can expect to achieve by ditching the creature comforts.

While you are at it, I'm sure people would like to also know how much weight you are actually removing.
 
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#27 ·
There is just one thing I’d like to point out. The m102 is a lethargic dog of an engine & as a direct result it won’t save you very much fuel because it will be maxed out most of the time. Converting back to a m102 in any w124 would be a mistake. Manual trans or not the m102 is a horrid engine full stop.

For best fuel economy I would just ensure you keep the tyres at the correct PSI, keep the engine well serviced & use a high quality synthetic motor oil. Maybe even Octane Booster / Injector cleaner lubricant also if you like.

When my E220CDI gets near service time the MPG starts to drop. (Long Service intervals) so I usually service it sooner & the results are immediate with a marked improvement in MPG for a few months after.
 
#31 ·
There is just one thing I’d like to point out. The m102 is a lethargic dog of an engine & as a direct result it won’t save you very much fuel because it will be maxed out most of the time. Converting back to a m102 in any w124 would be a mistake. Manual trans or not the m102 is a horrid engine full stop.
I had both M102 and M103 powered W201s at one point. I kept the M102 because it was quicker and more fun to drive.
 
#29 ·
my 1989 GLi had the 1.8L 16V DOHC engine, which was CIS-E. I am thinking it was 130HP, something like that. very free revving, pulled hard up to about 6500 rpm, with a redline around 7200. 3000 rpm was 60mph in 5th. i had that car up to 125 MPH a few times, and it was quite stable and sure footed.
 
#30 ·
Manuals were fun to drive back then because the cars were lighter and driver input was directly connected to the powertrain. Today, the computer filters out everything for the sake of emissions and protecting the life of the clutch. Today's compacts were the midsize cars twenty years ago. They increase in size, then compensate with more power.


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#33 · (Edited)
Just read this thread since I had not kept up this forum. Contrary to the common belief, reducing the weight of W124 will not give you a better maximum acceleration. It will give you slightly better gas mileage, but not the maximum acceleration. Because W124 is a rear wheel drive car, the maximum acceleration is determined by the maximum tractive force on the rear tires, which is in turn determined by the maximum static friction times the normal force acting on the rear tires.

During acceleration, there is a weight shift to the rear. Without going into the details of derivations, the maximum acceleration is not affected by the total mass of the car as long as the engine is powerful enough to give enough torque for the maximum tractive force. This is called traction limited acceleration. This is also the case we have for W124. You can prove this by flooring the gas pedal and your rear tires will spin, indicating the maximum engine torque is higher than the maximum tractive force times the wheel radius. A more powerful engine will allow you to get to a higher top speed, but not a higher acceleration. You are simply more prone to spin the tires to burn them with a more powerful engine.

Within such constraints, an effective way to increase the acceleration will be shifting the weight to the rear, such as adding a bag of salt to the trunk. The added weight will not reduce acceleration because the total weight is irrelavent as long as the engine is powerful enough (i.e., acceleration is traction limited). However, this will change the steering characteristic of the car, making it more prone to oversteering. Porche does this with its mass center very close to the rear tires, but you need to know how to drive it safely.

Believe or not, according to the equation, if you add some weight on top of the roof to move the mass center of the car higher, you can have a higher weight shift to the rear, thus higher acceleration. Therefore, instead of cutting weight, you actually add weight, either to the trunk or to the roof, if you want higher acceleration, but not too much weight to exceed the limit of the engine. Finally, you can change your rear tires to race car tires to get a higher static friction coefficient, but when it rains you are in trouble.

Finally, the above analysis is for the maximum acceleration. Reducing weight will give a sense of better acceleration because if you press down the gas pedal for the same amount, the same engine torque gives you the same tractive force but higher acceleration with a lower mass of the car. But this acceleration is lower than the maximum acceleration you can achieve.

In conclusion, try it out to see if Sir Newton lied to us.

jftu105
 
#37 ·
Actually the reason I made this thread was because of expected gas price increase. It happened. 1-1-2018 gas priced increased by +83% for 91 RON (~89 PON) and +126% for 95 RON (~92 PON). And that's after returning the original prices we had 8 years ago. Been thinking of replacing the wheels with lighter ones and higher profile tires to give more mileage on the highway I often take but ended up with the latter only.



About acceleration, is the 6L M103 powerful enough to keep the same acceleration if let's say extra 250-300 kg worth of people is on board (that's just a random number, BTW)?

And a 4 wheel alignment to check things like thrust angle.
Regular maintenance to keep the car in shape? No worries here, I always take care of this.

^This and remove any extra weight from the car you don't really need. This can be anything from bottles of water, baby seats, boxes of paper, extra car parts, to who knows what.

Also putting the driver on a diet can only help.
Check!

Only the bazooka sub-woofer is in the truck.

If your car has power seats, switch them out for manual ones. Those mechanisms are heavy.
You might be able to find that in Saudi.
They are manuals already :(

Good to know this turned out useful in the end.
 
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