Brakes for a Fiat 131 rally car

Non-engine, eg: aerodynamics, gearboxes, brakes, suspension
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miro-1980
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Brakes for a Fiat 131 rally car

Post by miro-1980 » Mon May 18, 2009 9:19 pm

HI,

I have been told that RS 9112 calipers ( aluminum ones ) fit into 13 " wheels.

For my new engine I will need to make the breakes much stronger . The rear will have original abarth diff and suspensin with
disc brakes , but the front ones must be upgraded big time.

Can anybody confirm this before I spent lots of euro's to buy them and learn about it the hard and costly way ?


Miro
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Walezy
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Re: RS 911 calipers for 131

Post by Walezy » Tue May 19, 2009 6:25 am

I used to have those brakes(actually the ones that have been used in 131 Abarth cars - ATE calipers) and it was nothing special. Much better(and cheaper) will be brand new Wilwood calipers or some Brembo 4 pots from Fiat Coupe for example. If you fit those ATE calipers then remember that works cars had balance bar with 2 separate master cylinders and no brake booster.
Last edited by Walezy on Tue May 19, 2009 9:09 pm, edited 1 time in total.
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Re: RS 911 calipers for 131

Post by Guy Croft » Tue May 19, 2009 10:18 am

My friends in Fiat brakes - Jon Logan of MidWest 124 and Jim Fierst of Whoa:

http://www.midwest124.com/Whoa_Brakes.htm


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Re: RS 911 calipers for 131

Post by miro-1980 » Tue May 19, 2009 11:36 pm

Tome, You say :
Walezy wrote:...... If you fit those ATE calipers then remember that works cars had balance bar with 2 separate master cylinders and no brake booster.

Ok , this sounds interesting , but what does it mean in practical terms?

Miro
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miro-1980
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Re: RS 911 calipers for 131

Post by miro-1980 » Tue May 19, 2009 11:41 pm

Guy Croft wrote:My friends in Fiat brakes - Jon Logan of MidWest 124 and Jim Fierst of Whoa:

http://www.midwest124.com/Whoa_Brakes.htm


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Guy,

The problem is I have 13" wheels ( actually three sets of them with slick and semislick and "rain" tires) and have no intention to change them for 14" or 15 " wheels , and it looks like they do not have calipers to fit my wheels.

Will call them to confirm tomorrow to confirm this and post the result.

M iro
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mickwood
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Re: RS 911 calipers for 131

Post by mickwood » Thu Jun 04, 2009 1:44 pm

RS 911 calipers certainly fit inside 13" rims - they were standard Group 4 fitment on Works 124 Abarth using 20mm Vented brake discs of around 256 - 260mm dia from memory. They then carried these calipers over onto early 131 Abarth G4 cars, running 15" rims which allowed 300mm discs.
I have used them on both cars and found they were fine.
That said, 4 pot calipers on the same discs were an improvement. Works 131 and possibly (I believe) some very late Works 124's were fitted with the AP lockheed 4 pot calipers as on G4 escorts - I have these on my 124 and they are as good as you are likely to need. They are readily available new from many suppliers as they are the DB in historic rallying. Just choose the right pads for the use you intend for the car.

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Re: RS 911 calipers for 131

Post by Jon_Logan » Sat Jun 06, 2009 1:48 am

The 131 kit MAY fit under the 13" rims. I know that the Series 1 124 kits did clear some of the 13" rims (I believe the stock Cromodora Iron Cross type but not the Speedline made ones. With my current 124 Spider, I have a full 14" Series 2 kit on with my 13" Cromodora rims and the caliper itself took only a little bit of radius grinding at the outer edge to make it fit fine under the 13" rim.

It is possible that the 131 kit just might work for you. I know there is a "jig" that Jim Fierst worked up to test fit the clearance in your rim. I could have you take some measurements and see if the kit would work for you.

Jon
Jon W. Logan
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http://www.midwest124.com
parts@midwest124.com
1979 Fiat Spider 2000, 10:1, Twin IDFs

miro-1980
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Re: RS 911 calipers for 131

Post by miro-1980 » Sun Jun 07, 2009 3:46 am

Hi Jon,

Thanks a lot for your reply

I have two cars :

- 124 CS0 , 1980 2.0 fi on original 14 " Cromodora CD 30 four spoke wheels- no modification to suspension, wheels, brakes, etc.
[ CORRECTION : THESE ARE BWA SPOSTRSTAR 14X 6 WHEELS !]
12 4 ORIGINALS .jpg
12 4 ORIGINALS .jpg (35.53 KiB) Viewed 8722 times

- 131 abarth rally replica based on 131 coupe body on 7" Smoor wheels ( 205/60/13 tyres) in front and same but 8" in rear.
SMOOR .jpg
SMOOR .jpg (60.58 KiB) Viewed 8722 times
I have two full sets of such Smoor wheels with tyres on them and two spare wheels. So naturally I would like to keep using them. I was actually planning to buy a set of CD 66 replicas to race on them , but cannot do this until I resolve the brakes issue.

In the future I will look to get original Cromodora CD 68's ( 15 " ) , but because of their cost and the fact these will be used , their use for sport is out if the question (show only !)

(There are supposed to be CD 68's replicas on the market later this year , but this actually may be delayed and I expect them not to be available until Q2 2010.)

I also have original set of Cromodora CD 66's
131 cromodora 13s.jpg
131 cromodora 13s.jpg (69.3 KiB) Viewed 8723 times
The 131 has 41 mm distance plates (see pictures, below)

1/
distamce plate 1.jpg
distamce plate 1.jpg (70.13 KiB) Viewed 8723 times
2/
distamce plate 2.jpg
distamce plate 2.jpg (45.22 KiB) Viewed 8725 times

The reason I am giving you all this informnation is two fold:

One : so you see I really need brakes to fit a 13" wheels
Two : so you see if the KIt we are talkonmg about really cannot be made to fit my 131 I can install it in my 124 ( which is good news of reduced risk if they do not fir 131).

Bottom Line : what measurements do I take to see if the KIT fits ?

Miro

PS : currently, as an immediate brake remedy we are planning to install Uno Turbo calipers with 240 rotors (or the larger rotors 257,5 rotors as used on the same calipers in Fiat Cinquecento Kit Car). These are one piston brakes ( 48mm - same size as in 131) but the disks are larger not 227 but 240 or 257,5- of we cam fir them - and are ventilated) But this is only a temporary solution as these these brakes will not stop my 131 on GC 180+ hp engine ).
Last edited by miro-1980 on Fri Jan 01, 2010 7:45 pm, edited 2 times in total.
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miro-1980
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Re: RS 911 calipers for 131 (interim brake upgrade)

Post by miro-1980 » Sat Jun 13, 2009 1:16 am

Gents ,

Awaiting my new GC engine completion I will use my current engine for what looks like most of this season. So I have decided to run a budget upgrade of the current standard calipers and cross cut and drilled Zimmerman 227 disk (which are still insufficient with this engine). This is an interim upgrade (before we actually fit the willwoods).

Here is the new setup we will start installing this coming Monday:

I am planning to install Unto turbo 240 mm diameter vented (20 mm thick cross cut) disks and calipers using Uno turbo mounting brackets. They should fir straight in. We will also change brake pump from standard 131 dia 19.5 mm to 20,6 mm (from an unknown Fiat model - i.e. this size used in Regata, 127 and others ) as well as put in steel braided flexible brake linkage. Note: my brakes in the back are still standard drums.

To make the data complete :
- front springs are actually stock rear 131 springs ( front has adjustable Bilstein shocks and the rear ones are none adjustable sport Bilstein shocks)
- the rear springs are modified stock front 131 springs cut off about two coils
- the car is on 13" wheels 7" wide ( 20 offset) front and 8" wider 0 offset in the rear with 205x60 Toyo R888 tyres.

The procedure we will follow is this:

- first: to install steel braided flexible linkage - to see what effect it has on the current brake system. I am hoping the brake pedal to become a bit stiffer.
- second change the pump and see the effect. I am expecting the pedal travel to be shortened just a bit and require more force but feel harder. (We will test this on existing broken-in brakes as this will be easier to test it in real driving conditions, than on newly installed not broken-pin brakes which we will install later )
- second we will install the new brakes with the same newly fitted 20.6 pump and see if it works to our satisfaction
- third (optional , if the result is not satisfactory: if the travel of the brake pedal is short and or the force required to brake too big -we will change back to the original 19.5 pump and see the effect.

Based on local racing experience these (240 mm vented) brakes and this ( 20,6) pump ( not the Uno Turbo 22.2 mm pump !) is the best low budget combination for 13 " wheels on Fiat 131.

We will see what happens , once we install it.

Will post the report on this after June 25th after we have raced the car on an air field track day with the new brakes for a day.

Miro

PS: Once the front brakes work to our satisfaction, we will adjust the rear brakes compensator to match the new set up.
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Walezy
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Re: RS 911 calipers for 131

Post by Walezy » Sat Jun 13, 2009 6:13 am

Check the brake booster and firewall for flex and try to make it stiffer. I have a flex of about 1cm there.
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miro-1980
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Re: RS 911 calipers for 131

Post by miro-1980 » Sat Jun 13, 2009 8:09 pm

Walezy wrote:Check the brake booster and firewall for flex and try to make it stiffer. I have a flex of about 1cm there.
Sorry Tomek .

Polish please (I am not shure what you mean ?)

Do you mean: bending of the firewall ( ugięcie ściany rozdzielającej komorę silnika od przedziału pasażerskiego) or is there a flaxible seal under the booster (pod servo jest jakaś elastyczna uszczelka)?

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miro-1980
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Re: RS 911 calipers for 131

Post by miro-1980 » Fri Jun 19, 2009 11:43 pm

Just done!

Ok, we are ready to race , the Uno Turbo calipers are installed ( perfect fit - no installation issue) and work fine. We had to readjust rear brakes (drums) to increase the braking of the rear.

The brakes feel fantastic . For the first time I was ble to block the front wheels on 205 semi-slics on dry tarmac.


The difference is really significant , and this should allow me to exercise much more control on entering curves and going out of them.

I have also bent the accelatrator pedal bar to make it lower. Now, I can brake with my right foot toes and accelerate with the heel. Accelerating after downshift should start at much higher RPM giving more torque and power on curve exit.

More detailed report once we complete the track day.

Miro
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miro-1980
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Re: RS 911 calipers for 131

Post by miro-1980 » Mon Jun 22, 2009 12:29 am

Gents,

The difference in event driving was even bigger than I expected. No braking problems, and much later braking .

I can decklare this a success !

Miro

PS still loooking to test if the 257 disks will fit. (There is never enough braking power )!

M
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achy
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Re: RS 911 calipers for 131

Post by achy » Wed Jul 08, 2009 7:44 am

Dear Miro

Well done with uno brakes. This is an improvement in comparison with the (useless) factory 227 disks but in my personal opinion they have not enough braking power. I had them for almost 10 years on my 124 sedan with 1800 engine and are not enough. You can use the 911 rs calipers with 257 disk as abarth did (although you will not find the right disk-the closer to specifications disk is Lancia delta HF turbo 257 mm ) which is surely much better than Uno, but the calipers are rather difficult to find (at least in logical prices) or you can try another mode I made . You can use Lancia HF 257 mm disks with the 4 pot calipers from Rover Metro which are dead cheap and can fit in 13 inches rims. This is a much cheaper solution and is equal effective in braking power (if not better).

Achy
124AbarthRallyeCorsa

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Re: RS 911 calipers for 131

Post by miro-1980 » Thu Jul 09, 2009 2:30 am

Dear Achy,

Thanks for this. This is very important , as what I have now (240 from Uno turbo)is very good for now but it will be far too little to stop the car with GC 190 hp engine.

I have access to reasonably priced 911 RS calipers. I know there is an issue with the disks.. From what you are saying I could use 257 ones from Lancia delta HF integrale?

Miro
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