600 Master Cyl & 850 caliper questions

[boxy02]

Hi, has anyone installed one of these dual circuit master cylinders into their fiat 600? It looks like it mounts perpendicularly to the stock master cyl orientation and uses a lever to transfer the force to the plunger. Any thoughts or experiences would be appreciated.

Uprated Brake Master Cylinder Kit - Fiat 600 | Italian Car Parts Specialists​

Also, I currently have what appear to be series 1, 66-68 850 spider front calipers installed on my 600 (PO installed). I’m calling them series one because they do not have the ears located on the ends of the pads. (Looks like these):

I think these are the series 2, 68.5-73 850 pads:

I need to either rebuild my series 1 calipers or change to the more available series 2 (‘68.5-‘73 850 sport & spider) calipers.

850 spindles and upper control arms are installed on my 600 currently.

Question: Can ‘68.5-‘73 850 front calipers/carriers be installed on an early ‘66-‘68 850 front end with no problem? And can stock 850 rotors or cross-drilled solid rotors be installed on the early 850 spindles as well?
thanks,
Mike

 

[boxy02]

Well my dual 850 master cylinder with custom 600 mounting bracket arrived today. Looks like it will fit nicely in the space above and just aft of the transverse leaf spring. Brilliant piece of kit, I think! I’ll take more pics when I install it.

 

[kmead]

Quite the construction on that unit. Looks like a typical 124 dual circuit MC or possibly the 850 one for US cars.

Personally I would look at alternative calipers as the later 850 ones (new ones are available from MWB) are less than ideal, I have not changed mine but am sorely tempted.

Ditchdigger used some motorcycle ones which are very similar to the typical Wilwood fixed calipers with floating pistons. Page three at the link below.

His story is worth the read: https://forum.retro-rides.org/thread/70073/1971-fiat-sedan-resurrection-starts

 

[boxy02]

Quite the construction on that unit. Looks like a typical 124 dual circuit MC or possibly the 850 one for US cars.

Personally I would look at alternative calipers as the later 850 ones (new ones are available from MWB) are less than ideal, I have not changed mine but am sorely tempted.

Ditchdigger used some motorcycle ones which are very similar to the typical Wilwood fixed calipers with floating pistons. Page three at the link below.

His story is worth the read: https://forum.retro-rides.org/thread/70073/1971-fiat-sedan-resurrection-starts

Thanks, I’ve read that thread as well. I’m running Cromodora CD3 13x5 mag wheels and I don’t know if the calipers used by ditchdigger would fit under my wheels. But the series 1 850 calipers I have now are definitely not inspiring confidence during braking at nominal speeds. I’ll need the do a bit of measuring on my CD3s and see what may fit better. I’d love to use a vented rotor.

 

[kmead]

Thanks, I’ve read that thread as well. I’m running Cromodora CD3 13x5 mag wheels and I don’t know if the calipers used by ditchdigger would fit under my wheels. But the series 1 850 calipers I have now are definitely not inspiring confidence during braking at nominal speeds. I’ll need the do a bit of measuring on my CD3s and see what may fit better. I’d love to use a vented rotor.

I don’t know how you drive or what engine you have but I doubt there would be much value in vented discs on most 600s. Not that I ever do things that are entirely not needed

I don’t know how much space the Tokicos take up but they are not much different from standard. If anything you might need a spacer to move the rim outward to create the space relative to the back of the rim which is where I would expect might be an issue.

 

[boxy02]

Thx Kmead. Yeah, I have a tendency to overdo. I’m running hopped-up 903 currently.
The goal is to obtain and install a slightly hopped-up A112. It’s already pretty zippy due to almost zero interior and I have a set of Mg cromodoras to replace the 124 steelies on it now.
I’ll likely look into the Tokicos & reread ditchdiggers thread.
Thx, Mike

 

[dnudelman]

Just wondering why you would not use a set of brand new 124 calipers from Autoricambi?

 

[kmead]

Thx Kmead. Yeah, I have a tendency to overdo. I’m running hoped-up 903 currently.
The goal is to obtain and install a slightly hoped-up A112. It’s already pretty zippy due to almost zero interior and I have a set of Mg cromodoras to replace the 124 steelies on it now.
I’ll likely look into the Tokicos & reread ditchdiggers thread.
Thx, Mike

I have also been looking at the front brakes for a MB Smart Fortwo as an alternative. They have a 42mm diameter piston, so moves the bias rearward. It is a modern floating caliper so more reliable than either of the 850 type calipers.

A stripped 600 with a 1050 would definitely be a hoot. Too much is never enough

 

[kmead]

Just wondering why you would not use a set of brand new 124 calipers from Autoricambi?

124 calipers are 48mm in diameter which will move the brake bias even further forward which has always been an issue with these cars as they tend to lock up the fronts.

I wouldn’t put 124 calipers without also fitting a proportioning valve.

 

[boxy02]

Just wondering why you would not use a set of brand new 124 calipers from Autoricambi?

I don’t know if 124 calipers/brackets bolt onto the 850 spindle. Also, I think they wouldn’t fit inside the Mg Cromodora CD3s I plan on running. Still doing the research for cross-fit of parts for the various models of the era. If I did use 124 fronts, would using 124 rear calipers balance it out? Or would it still require a proportioning valve? I’m guessing since that setup was used on a front-engine car, installing them on my rear-eng car would not end up with the correct bias.

 

[kmead]

I don’t know if 124 calipers/brackets bolt onto the 850 spindle. Also, I think they wouldn’t fit inside the Mg Cromodora CD3s I plan on running. Still doing the research for cross-fit of part for the various models of the era. If I did use 124 fronts, would using 124 rear calipers balance it out? Or would it still require a proportioning valve? I’m guessing since that setup was used on a front-engine car, installing them on my rear-eng car would not end up with the correct balance.

I would need to run it through a spreadsheet I picked up but my expectation is you would still have too much front bias.

The 124 caliper is not really much bigger than the series 2 850 caliper, particularly on the ‘rim’ side

You are running 13” rims right rather than the 12s? If they are 13s you should have enough room.

 

[boxy02]

I would need to run it through a spreadsheet I picked up but my expectation is you would still have too much front bias.

The 124 caliper is not really much bigger than the series 2 850 caliper, particularly on the ‘rim’ side

You are running 13” rims right rather than the 12s? If they are 13s you should have enough room.

Yes running 13x5.

 

[dnudelman]

To use the rear 124 calipers you'd have to build a bracket. I know those who did for the 850's and they really weren't happy with the results. I would use 850 drums. I think my alemano has 850 drums. The fronts are a special magnesium calipers that came with the car. Same car has the 13 inch steel wheels. If you don't have already, download a copy of Greg Schmidts Fiat & Abarth tricks.

 

[boxy02]

To use the rear 124 calipers you'd have to build a bracket. I know those who did for the 850's and they really weren't happy with the results. I would use 850 drums. I think my alemano has 850 drums. The fronts are a special magnesium calipers that came with the car. Same car has the 13 inch steel wheels. If you don't have already, download a copy of Greg Schmidts Fiat & Abarth tricks.

I do have Greg’s book, I’m actually re-reading that section right now (I need to make some notes).

I have a cardboard template for the rear 124 caliper to mount on the 600 trailing arms, I just haven’t fabricated them yet, as I haven’t decided which way I want to go.

I thought the 600 rear drums/wheel cylinders were the same as the 850. Are they?
Thanks for the ideas and discussion. As you can see, I’m still learning, but having fun along the way.
Mike

 

[dnudelman]

600 drums smaller

 

[kmead]

I do have Greg’s book, I’m actually re-reading that section right now (I need to make some notes).

I have a cardboard template for the rear 124 caliper to mount on the 600 trailing arms, I just haven’t fabricated them yet, as I haven’t decided which way I want to go.

I thought the 600 rear drums/wheel cylinders were the same as the 850. Are they?
Thanks for the ideas and discussion. As you can see, I’m still learning, but having fun along the way.
Mike

We are all still learning. Except for Jeff Stich, he does in fact know it all

I think Jeff has done or seen just about anything relating to rear engine Fiats, I never cease to be amazed at his knowledge.

My Sport Coupe is effectively stock with most of its original parts intact outside of brakes, tires, hoses and fluids. It does have a high torque starter which I put in a number of years ago. It needs all the bushings and kingpins replaced, they are just old…

In doing performance upgrades one does want to ensure you don’t do something which doesn’t improve the performance. Braking is an area where you can make real mistakes. I will find the brake system spreadsheet on my computer tonight and see if I can create more questions.

I assume your car is around 1500lbs with around a 40/60 weight distribution.

 

[boxy02]

In doing performance upgrades one does want to ensure you don’t do something which doesn’t improve the performance. Braking is an area where you can make real mistakes. I will find the brake system spreadsheet on my computer tonight and see if I can create more questions.

I assume your car is around 1500lbs with around a 40/60 weight distribution.

Thx. Looking forward to more questions.
I think your assumption is pretty accurate, when all is done I’ll corner balance and align it (get all the weight stats and such).
Mike

 

[ramona300]

I have Tokico callipers and they easily fit behind 13 X 6" alloys. They are half the weight of the Fiat items and they are all the brakes you will need.

 

[fiatfactory]

I don’t know if 124 calipers/brackets bolt onto the 850 spindle. Also, I think they wouldn’t fit inside the Mg Cromodora CD3s I plan on running. Still doing the research for cross-fit of part for the various models of the era. If I did use 124 fronts, would using 124 rear calipers balance it out? Or would it still require a proportioning valve? I’m guessing since that setup was used on a front-engine car, installing them on my rear-eng car would not end up with the correct balance.

124 uses a 48mm piston up front and a 34mm piston at the rear, exactly the same as a mid engined X19.

If a CD3 will fit over the front discs/calipers on a 124 or 128 or X19, then it will fit a 600 with discs up front too.

SteveC

 

[boxy02]

I have Tokico callipers and they easily fit behind 13 X 6" alloys. They are half the weight of the Fiat items and they are all the brakes you will need.View attachment 68723

Ramona300, what rear brakes are you using? And do you use a proportioning valve?
Would you be willing to measure the radius from the center of the hub/spindle nut cover to the furthest point on the end of the Tokico caliper? I like the idea of using the Tokico quad-piston unit over the single piston sliders.