Should you upgrade brakes when you upgrade power

[Zuban]

Sorry this is a bit random but today i was involved in a discussion on another forum where the reasoning given that when a cars power is upgraded, engine transplant in this case, that the brakes dont need upgraded because the stopping distance between the car pre and post upgrade is the same as the weight hasnt changed, which in this instance it hasnt. And that only if its going to be used on track they should be upgraded. so both cars travelling at 100mph take the same time to stop, so therefore the brakes dont need upgraded.

now personally, i'd have thought it depends on so many factors, what the stock brakes were like, how much power is being added, where and how its going to be driven that to make a statement like that is pretty ludicrous, i can think of a few reasons why i think its a pretty stupid thing to say but would like to see what others think as i seem to be the only one that thinks its a bit short sighted!.

 

[Clarkey]

Depends how much you're going to use the power doesn't it. Make proper use of it and yes of course you'll need an upgrade to retain the same braking. The extra energy is going to end up in the braking system unless the cornering speed has also been dramatically increased. For motorway cruising, not going to be needed.

 

[Mucky_Pup]

Depends how much you're going to use the power doesn't it. Make proper use of it and yes of course you'll need an upgrade to retain the same braking. The extra energy is going to end up in the braking system unless the cornering speed has also been dramatically increased. For motorway cruising, not going to be needed.

Pretty much this, me hurling my car round Silverstone, or on a tight and windy B road my standard brakes were meh, but cruising along the motorway or round the doors at 30mph they were more than adequate. But I have upgraded to 6 piston AP's and now they're not meh in either instances.

 

[Gaygle]

It's not about the stopping distance due to the weight of the car. Often it's because fast cars, are normally driven faster and can reach higher speeds easier and quicker - hence higher speeds are more likely to be used meaning big brakes needed.

Ie. a 204bhp 325d that weighs 1525kg has 300mm front brakes, whereas a 335 with 306bhp has 350mm brakes despite weighing only 75kg more.

 

[Greboth]

It would always be on my mind that if my car was suddenly 2 times as quick that I couldn't stop quicker. However it does entirely depend on the use of the car as braking is entirely based upon speed so for road driving where everyone obviously sticks to the indicated speed limits then it doesn't matter if you have 100bhp or 1000bhp 30mph - 0 will still take the same time.

Edit: I meant to say, as said above, that if you are a car nut enough to drastically increase the power of your car it is likely that you are going to use the extra power so I would say it is sensible to increase brakes along with power however it isn't, in the truest sense, necessary.

I remember reading (can't remember who or specifically which car) that a garage giving an evo a 2.2 stroker engine wouldn't do it until the owner upgraded the brakes too which is sensible as they are good for sooooooo much power.

 

[miniyazz]

So if you're just using the extra power to accelerate to the speed you would be going anyway, just getting up to speed more quickly, nope

 

[Greboth]

Exactly, because we all obey the law and never under any circumtance ever break the speed limit or drive in any way which may be considered in the slightest bit dangerous on public roads.

 

[naefeart]

Maybe I'm being too simplistic, but in it's simplest terms: Force = Mass x acceleration.

If you increase the power of the car, but maintain weight, assuming you use this increased performance (why change the engine if you're not going to) this will still lead to an increase in effort for the braking system to slow the car. Doesn't matter if you still cruise at the same speed as you did before the engine transplant.


My answer, if there is a reasonable increase in power - new brakes please

 

[Maccapacca]

Was reading JC's new book the other day and he says that the reason for a 155 mph digital limit on most cars that can exceed 155 is that they can't fit / afford the brakes they would need.

 

[Clarkey]

Maybe I'm being too simplistic, but in it's simplest terms: Force = Mass x acceleration.

If you increase the power of the car, but maintain weight, assuming you use this increased performance (why change the engine if you're not going to) this will still lead to an increase in effort for the braking system to slow the car. Doesn't matter if you still cruise at the same speed as you did before the engine transplant.


My answer, if there is a reasonable increase in power - new brakes please

What if the brakes are perfectly adequate to begin with? For example, brakes on my 328i are the same you would find on a 318i.

 

[Jonnycoupe]

1/2 mv^2 is more relevant really.

The speed you are going gives the car kinetic energy. When you stop the car with brakes you have to turn that kinetic energy into heat.

No difference with the power, just more power will tend to mean you need to go from a higher V to, for example, 40 for a corner .... and so on on a B road blast.

It right that you dont need to, but if you are making a car more capable then you should really take a holistic view to all attributes.

My Wilwood 4 pots on my DC2 were amazing for that.

 

[Zuban]

well i agreed it isnt actualy needed, it was the reasoning i had a problem with, it seems a very simplistic point of view, and one that really only applies to one set of circumstances, and makes too many assumptions.

 

[233]

really depends on the car in question

some cars are woefully underbraked as standard.

the wifes focus diesel has poor brakes. whilst their fine for the 99% of driving it does if you hoon it they really are not up to the job.

the Cupra R on the other hand came with Brembos as standard, took that up to nearly 300 bhp and never gave a moments thought to uprating the brakes in any way as no amount of driving like a *** could induce any concern regards stopping.



of course if you have concerns you can always buy some "proper" braking

fitted these to my golf and the difference was night and day.

 

[Dr Who]

really depends on the car in question

some cars are woefully underbraked as standard.

This.

Some cars have terrible brakes Early UK impreza's to name but one.

Some cars have exceptional brakes, ie Impreza STi's Brembo Brakes but you may wish to improve the pads, lines, fluid and discs anyway. Lots of car brakes are more than adequate for increased power but will suffer from fade, disc overheating, fluid boiling and other ill effects when used on the track.

So starting point and intended use it what is important. not how much additional power you put into it.

 

[Zuban]

really depends on the car in question

some cars are woefully underbraked as standard.

well I've cooked the brakes on 2 models of the cars in question, although the statement didn't seem limited to just those cars but any, one with uprated pads in which case I think it was the fluid that became the issue, which according to the same person doesn't happen and will only happen on track with or without increased power lol. I managed it on the backroads near my house... but never managed to cook those same brakes going round castle combe!

 

[#Chri5#]

This.

Some cars have terrible brakes Early UK impreza's to name but one.

2 pots terrible? Give over

My MY99 Scooby had four pots but I had them upgraded with Group N discs, DS2500 pads and braided lines. I ran out of bottle long before the brakes.

 

[Mucky_Pup]

My 362mm 6 Pot AP's omnomnomnom

Got them for a decent price, but haven't had to replace the discs and pads yet, I'm sure my eye's will water at that time

 

[jon.bda]

IMHO if your modding a car like that, brakes and suspension should be the first thing to be upgraded, ready for whatever extra power...

 

[Dr Who]

2 pots terrible? Give over

My MY99 Scooby had four pots but I had them upgraded with Group N discs, DS2500 pads and braided lines. I ran out of bottle long before the brakes.

They used to scare me at the best of times

4 pots with braided lines and kevlar pads worked great on my Forester S/Tb tho

 

[MOOGLEYS]

High power cars have bigger breaks to bleed off speed quicker. If you increase the cars ability to accelerate it makes sense to increase its ability to deselerate as well. There is a lot of Kinect energy in a car accelerating hard and if that energy is suddenly needed to stop bigger breaks with a bigger friction contact area will be an advantage.