Brake upgrade

[FrankBelgium]

The "winter job" is just finished on my car:
-Eibach springs (Koni's were already on the car)
-Super pro bushings
-Whiteline ARB
-Rear tie rods from the january group buy
-Sway bar end links from TwoRus
and my car feels razor-sharp again except from the brakes.
I flushed the brake fluid and to be honest it was already a big difference! But I read a lot about the ST165 calipers upgrade and started looking for some calipers in Belgium. I managed to find a guy who is selling a pair with brackets and went to his workshop today to buy them. The workshop was Celica heaven but then the dark, dirty version! Celica's, engines, suspension parts everywhere ... It appears the guy's job was preparing and renting Celica for the rally. He asked me why I need the parts and I explained him the whole story.
He explained me the modification would almost give no added value, and I could better safe some money and buy some EBC Yellowstuff and new brake discs.
I already checked and the Yellowstuff pads aren't available for a Mk1a. So I'll have to buy the Redstuff.
And in both cases I 'll have to buy new discs.
The guy works more then 30years with rally cars, so I guess he knows what he is talking about! And from my point of view, the best way to upgrade brakes is to put larger discs and calipers but I want to stick to the original 14" rims.
So I would like your point of view because I'm a little confused!
Is it worth the modification? Did someone could compare the two systems?
Is the fact you refurbish the ST165 calipers and put new oil give you the feeling it brakes better than the old system?

Thanks!

Frank

[PW@Woodsport]

He explained me the modification would almost give no added value

He's wrong, your stopping distance will be reduced using the Celica calipers alone, proven countless times over the last ten years and not just by me.

[kevin..in]

it is a fact that braking force is dictated by the size of the master cylinder
a master cylinder of X size can only produce X amount of force at the slave cylinders (calipers) increasing brake pad/disc surface area will only spread the same force over a wider area
all of the above can be proven by using maths
the unknown (but proveable by experimenting) element in the equasion is how efficient std. and upgraded calipers/discs are at transforming the available force into braking
so if the celica set up is more efficient at using the available force you will see a decreased stopping distance for any given speed over the std set up
there is another upgrade using a bigger master cylinder from a MK2 this Will increase braking force at the discs no matter which caliper you use

Both the rally technician and Paul woods are correct even though they seem to dissagree
Paul has experience of the unknown element of the equasion the rally technition seems to be talking about just pure theory
then there is always the placeobo effect of any mod i.e. put a TRD sticker on and you gain 20 BHP thats a fact

[PW@Woodsport]

Yep, there's no substitute for real world first hand experience.

It's a nice upgrade and it works, that's all i know. By the way Kev i got 25bhp from my TRD badge

[kevin..in]

Yep, there's no substitute for real world first hand experience.

It's a nice upgrade and it works, that's all i know. By the way Kev i got 25bhp from my TRD badge

yeah but i've got a TRD horn push so while I have only gained 20 BHP its a loud 20 BHP!
further gains are to be had for those who can correctly spell Placaebo

[stenky]

i have done some vague calculations of different brake setups for mk1 and with certain setups (celica calipers + mk2 22V) you can gain up to 35-39% (depending of celica caliper used) more stopping power over stock mk1b (which is even more over mk1a) while maintaining near stock force distribution. i hope my calculus was right i am gathering the parts already and also i am about to try the Megane disc setup for the rear, which i've found may work better than clio, mk1b or corrado disc.

[elbon50]

i am about to try the Megane disc setup for the rear, which i've found may work better than clio, mk1b or corrado disc.

Hope you will let us know how you get on with that Stenky

[FrankBelgium]

Yep, there's no substitute for real world first hand experience.

That was exactly what I wanted to hear! Thanks guys!
For me the real world experience is far more important than maths. And you guys did a lot of conversions. I was confused because the rally guy didn't earn any money at giving me the advice.
I think the problem is that our reference is different. He makes conversion to his rally cars, lot of BHP and really big racing brakes.
My idea is to keep the car as stock as possible.
In his eyes, the difference between a stock system and ST165 brakes is nihil compared to the difference between stock and a 2000euro race setup...
Anyway, thanks for the advice and I think I 'll give him another visit!
I'm preparing for the rolling eyes and 'I told you...' the rally guy is 60years old!

cheers,

Frank

[stenky]

i am about to try the Megane disc setup for the rear, which i've found may work better than clio, mk1b or corrado disc.

Hope you will let us know how you get on with that Stenky

i have just cleared the payment for a pair of decent 22V rears, so i will try that out very soon

In his eyes, the difference between a stock system and ST165 brakes is nihil compared to the difference between stock and a 2000euro race setup...

even the mk1b conversion is worthwhile for a mk1a. mk1b+ ST165/185 twinpots simply has to be by far better than stock mk1a.

[elbon50]

Hope you will let us know how you get on with that Stenky

i have just cleared the payment for a pair of decent 22V rears, so i will try that out very soon

What exactly are 22v rears please Stenky ?

I don't understand about that

Are they some sort of Mk2 rear caliper

I have some ST185 twinpots to go on my 1b

Will probably need to upgrade the rears to get balanced braking

[stenky]

22V stands for SW20 rev2+ (or was it rev3+?) rear caliper size used over 22mm vented discs (rev1 used 16V-> 16mm vented)

http://www.imoc.co.uk/forums/viewtopic.php?t=159352

according to my calculations, twinpots front and 22v rars should increase the stopping power of a mk1b by 39% and you don't need to touch the bias valve. brake force distribution should be near stock 70:30 front to rear i havent tried this yet. with my car on jackstands, i am just another theory guy, but once i try it i'll write that up. brake upgrades on mk1 are quite often discussed these days. there are bits of information in every topic but some sum-up would help a lot

[PW@Woodsport]

I was confused because the rally guy didn't earn any money at giving me the advice.

I don't earn any money from it either, not a kit i supply or anything, it's just one of my discoveries.

[FrankBelgium]

I don't earn any money from it either, not a kit i supply or anything, it's just one of my discoveries.

No money Paul ... but you have my eternal gratitude all the way from Belgium! + a fix road assistance adres if some of you guys gets stucked again in Belgium with his car!

[MartG]

I want to stick to the original 14" rims.

Frank

the ST165 twin pots fit under the standard 14" wheels

I have some ST185 twinpots to go on my 1b

Will probably need to upgrade the rears to get balanced braking

Gutting the bias valve will give you the same braking balance as standard front to rear with the ST165s on the front and standard 1b calipers on the back ( worked out when I was fitting them to my track car )

[BarronMR]

I get the feeling I'm going to regret this post

The only reason I can see switching to st165's, resulting in a car stopping in a shorter distance over a straight line, single stop is from a change in brake bias from front to rear.

Good technical article here:
http://www.stoptech.com/technical-suppo ... -selection

[MartG]

single stop

There's your problem

If all you're ever going to do is stop once, then you don't need to upgrade your brakes. In the real world however, especially on track, upgraded brakes give the ability to stop quickly repeatedly without the brakes overheating etc.

[MrLuke]

Are the discs the same size on the st165 setup? If not you will have a larger leverage effect. It may be the same force but applied at a greater distance from the pivot, moving the earth and all that.

[MartG]

Same size disks, but larger pad area and higher clamping force as the two cylinders are greater area than the standard single one

[BarronMR]

single stop

There's your problem

If all you're ever going to do is stop once, then you don't need to upgrade your brakes. In the real world however, especially on track, upgraded brakes give the ability to stop quickly repeatedly without the brakes overheating etc.

Indeed lol, I was just trying to say that more piston area ie bigger calipers will *not* shorten your stopping distances, purely because you have more brake force. But a bias change will.

Also Im just not sure everyone needs to go straight for the bigger setups.

Start logically and give the standard ones a good overhaul and pop some performance bits in.

If I was cooking my brakes on the track, on a perfectly good stock system with all the reasonable upgrades, pads, quality fluids etc...

Then i'd look at perhaps bigger brakes.

Although upgrading stock stuff may not look good value for money, but when you consider like for like this adds no weight.

I've only got experience of the mk1 ST185/tubby setup, but that added over 10Kg's of unsprung mass and a % of that was rotating mass

And the stock setup has allowed me to lose another 30kgs of rotating mass from the wheels (17's to 14's) lol.

Anyone know if 13's will fit over rear stock setup

[MartG]

Indeed lol, I was just trying to say that more piston area ie bigger calipers will *not* shorten your stopping distances, purely because you have more brake force. But a bias change will.

Not necessarily - in the standard setup the rears aren't providing as much braking as they could thanks to the bias valve. With ST165 front calipers and the bias valve gutted the bias is approximately the same as standard, but overall braking is improved whilst still having the safety of the fronts locking before the rears.

And don't forget that in most cases cars with upgraded brakes will usually also have more overall grip than standard as they'll probably be running bigger modern tyres with more grip than the OEM ones back in 1985 so are less likely to lockup with the higher braking forces IYSWIM