can i remove my power brake booster for racing?
 

i was reading about a car that he removed the power brake booster for racing purposes. anybody know if this would work on a 1984 123 280e euro?

this is for a car to be used exclusively on autocross tracks so please don't bother the lectures on safety.

it it is feasible i will just take it off and try it out and if it doesnt work back on it will go.

i seem to remember on older cars the bolt pattern was the same for the booster as the mc so you could just unbolt it and take it out.

tom w

The bolt pattern is half the job. You also have to make the pushrod fit properly. That's the hard part, unless it happens to be the right length already (which I doubt). The easy part is making new lines to fit the new position of the cylinder outputs.

Disconnect the vacuum to the booster and see how drivable it is. I would think the booster would be an asset for racing as it improves your brakes. Some of the best cars were known not just for their acceleration and cornering capabilities, but for how good their brakes were.

You will have to use both feet on the pedal to stop the car, I would leave it in there. You can, I suppose, fit a modified (smaller bore) MC for racing, but otherwise you will have to priovide MUCH higher pedal pressure for equivalent braking.

Safety is much more important in racing that on the street -- you are going faster, working the car harder, and likely have much less effective manouvering room! Don't wait until you break your neck to think about it.

Peter

It weighs what, 7 pounds at the most? Your stopping distances will be longer no matter how strong your legs are.

Have you gutted the interior and trunk? You'd probably be better off doing that and getting some lighter rims and tires. My 14" bundt and 195/70 series tire weighed 25 pounds... decent but definitely room for improvement in the unsprung weight category.

Are you using the stock schoolbus steering wheel? Go for a 14" or a 15" aftermarket wheel like a Nardi (if you like wood). You will be amazed at how much more responsive it will feel with the smaller wheel, plus without all the vinyl/rubber material like on the OEM wheel you will feel a lot more through the wheel.

I wonder why people have to play around with the brakes (as I recall my studies at MB germany, brakes are made to stop a vehicle at the least possible distance and less effort on the driver) WHY MESS AROUND WITH IT? Short of saying you can just drive the car over the cliff just to commit suicide. WOW were are you guys from?

France

I FULLY expect that when removing the brake booster for racing purposes, they are using a master cylinder with a different size bore to make the brakes usable.

In the days of power brakes being an option, the non power brakes had a different size master cylinder.

Why do you want to remove it?

are you saying the bolt pattern is the same?

thanks for responding with an answer to the question that i asked.

tom w

thanks, larry. i knew that.

tom w

thanks to everybody for your kind thoughts and concerns. it is autocross so if the experiment doesn't work i am not likely to die.

finding a smaller diameter cyl may be a good option. but i am curious to find out how much more effort is required without it.

on my old caddies and pontiacs i routinely removed and discarded the power setups and found the brakes worked really well without them.

i fully expect a mercedes to have a better balance though between pedal effort and braking results.

i intend to fit a smaller diameter steering wheel if i find the hub is the right size. i have a very nice sport wheel from a saab of the eighties.

tom w

I auto crossed a 280E for 3 years in SCCA events... no real reason to disconnect or remove the booster..Use front brakes from a late W126 chassis with ceramic pads...you will have a GREAT feel that way.

Disc brakes need boosters
 

Drum brakes were "self-energizing".

In theory, yes. In practice, almost none. I have never seen such a system on a car, although I did own a motorcycle with self-energizing front drums.

No, I'm not saying that as I don't know. But it is quite possible.

Now THERE'S some good, been there, done that advice!

To see what it feels like without the power booster. Pump the brakes about 10 times with the engine off to exhaust the reserve left over and step on the brakes. Either that or disconnect the vacuum supply to the booster. Do not do this on a public road the first time. At best, try it on your driveway as long as it is not inclined very much.

If you keep the same size master cylinder, you will find there will be a tremendous difference in pedal effort required to stop a car with disk brakes wth no power booster. I would bet it requires significantly more than 10 times the pedal pressure. As an abover poster stated, you will literally need both feet on the brakes to even notice that you have applied the brakes.

how much help do you think that throwing 10-20lbs overboard will give you when racing versus the security of good brakes?stripping the doors would surely be of more value.

If you are trying to gain all the power from your Eng. with little or no lose from vacuum at the power plant,then you might think of a vacuum pump to run the power brakes.But what do you do for all the other possible vacuum leaks? Now a days people are using power steering thats a drain on the engine too,Find another way to do it, you will need to drive in hard and have good slowing power for the turns in order to be competitive,JNT

Does the booster affect pedal effort if it is disconnected from the vacuum source?

Yes.

thanks. actually this car came from the factory that way. and i plan to put it back one of these days as the vented rotors have been removed along with the larger calipers.

tom w

this is what i thought. i am wondering how much percentage of boost is actually used.

as i stated above, on a 52 cadillac the master cylinder is the same boosted or unboosted and the pedal pressure with the boost is way too low and too easy to lock up the brakes.

if it is easy to do i want to just try it and see how much different it is.

i have had benzes with power and no power steering and the difference is slight except at low speeds and the feel with manual is much superior.

tom w

I've felt what it is like on cars such as the W202 and W208 with no boost at very low speed. I don't think I would be able to stop the car with both feet on the brake from any amount of speed. As a wild ass guess, I would dare to say you would be looking at required pedal forces well into the hundreds of pounds to stop the car. I don;t know if I may be exagerrating but I am sure it takes significantly more than 10 times the pedal effort. Maybe at least 25 times or more the pedal effort with no boost.

You can give it a very, very catious and low speed no one around try and see what you think. I honestly think on a car with disk brakes and no booster, you will forget you even thought of the idea when you see what it feels like with no boost. It is probably downright scary.