Front brake option

[Dr.Jeff]

In another 'brakes' related discussion I mentioned something about the possible adaptation of front brakes from the "New 500" onto the "X". The new 500 has larger, vented rotors with larger calipers.

Please, before this gets side-tracked...this discussion is NOT about the merits/faults of upgraded brakes, the X's stock braking potential, unsprung weight, balancing front to rear brakes, or other such issues. I am simply curious about the ability to actually adapt the 'new 500' brakes; specifics on what is required, what fits or does not fit directly, etc. [Sorry, I don't want to sound offensive but I'd like to focus this discussion on the mechanical aspects only. Feel free to start another thread elsewhere if you are compelled to discuss other aspects.]

Dan S posted references to kits offered by Allison and Vicks. I believe those kits use the rotors from the new 500 but not the calipers? From what I can tell, Allison's kit for the 124 uses the rotors and calipers, as seen here:

But the Allison's X1/9 kit only uses the rotors with Wilwood calipers:

I'm not certain about Vick's kit, are those 500 calipers?

Do the 500 rotors directly fit the X spindles, are the mounting dimensions the same, are modifications required?

And what about the calipers? Obviously some sort of adapter bracket is needed between the X's mounts and the 500 caliper. But are there other issues, perhaps with the 500 calipers design? Are they intended for direct hydraulic action or do they have various interfaces for ABS, speed sensors, etc that would preclude that? Naturally wheel clearance would need to be addressed. How about strut (or other structures) clearances?

As with any brake system change, the master cylinder's capacity must be considered.

Has anyone attempted this yet? Honestly I'm not planning to build such a kit but am very curious about it. That's why I put it in the "discussion" area rather than "workshop" [Mods, feel free to move it there if desired.]
Thanks

 

[kmead]

Mark Allison's kit uses 500 rotors.

The Vicks kit uses Bosch calipers which are used on a variety of newer European cars. I believe they use the rotors from the 500 but am not sure.

Hussein (look for joe) has the Prima kit from Vicks on his upgraded X. The Prima kit calipers have the same piston diameter as a standard Fiat caliper thus there is no change relative to the master cylinder.

I don't know what the new 500 caliper piston diameter is so can't speak to their effect on the master cylinder fluid changes would be.

Another alternative you haven't asked about is the Uno Turbo front caliper system which uses a floating caliper and a bracket that bolts directly to the X front upright. The last set I saw (front and rear with brackets was on ebay for 400). This is a solution that Bernice has on her early X.

As Bernice will happily tell you the way to really improve the performance of the whole system is to increase the rear braking performance. This is done by increasing the rear brake piston diameter by going to rear calipers from the Fiat 125. This does increase the travel at the pedal a small amount but increases the amount of effective braking that can be done by the rear wheels. This changes the bias which can make the car a bit more dicey in wet weather. Both Hussein and TonyK have installed this solution and have run into some problems due to the newer calipers having some differences in the adjuster mechanism which causes more runout and even more pedal travel.

 

[Dr.Jeff]

Thanks Karl, lots of good info.

The 500 components are interesting because they can be readily found new, not too expensive, and have lots of pad options available. Especially if the rotors are a direct fit on the X hubs (as it appears). Mounting the caliper should not be too difficult by machining an appropriate adapter bracket. When compared to locating scarce components like from a Uno Turbo, or the cost of aftermarket stuff like Wilwood, or rebuilding old parts for a mix-matched arrangement, this might be a viable option.

Any more specific info on what those Bosch calipers are? I don't recognize them.

 

[fiatfactory]

In a similar way that back in the 70's most Fiats used the same Bendix front calipers, these days a lot of the modern Fiats use Bosch made calipers, 500/Punto/Panda (the three models we have in Australia) all (for the base models) use the same front caliper, which looks a lot like the caliper shown in the Vic's kit.

this ebay Italy ad shows the caliper fits 500/punto alfa mito and quite a few others including an opel corsa/holden barina (which shares the same suspension struts as my grande punto too)
http://www.ebay.it/itm/PINZA-FRENO-...732829?hash=item3ae462075d:g:LKIAAOSwn-tZGamg

SteveC

 

[Dr.Jeff]

Thanks Steve. That got me looking at part numbers, cross references, and supplier listings. The US spec 500 seems to use a different caliper from the many other models with a common Bosch caliper (like in Steve's listing). The US 500 calipers that look like this:

View attachment 3376

Definitely not the same as the Bosch item used in Vick's kit, but certainly the same as in Allison's 124 kit (but not the X kit with Wilwoods).

 

[fiatfactory]

Must be a difference between the Mexican assembled Fiats and the European assembled Fiats ... possibly something to do with 'local content'??

SteveC

 

[Dr.Jeff]

I'm not very familiar with the new 500 but seems like its very different from the 500 the rest of the word has. Apparently the US variant was developed independently, per Wikipedia:
"The North American 500 is marketed in Pop, Lounge, Sport and Turbo trim levels with market-specific modifications including increased body strength; revised suspension; changes for reduced noise, vibration and harshness; BiHalogen projector headlamps and amber front and red rear sidemarker lights and reflectors on each wheel arch edge to comply with FMVSS 108; new four-wheel anti-lock disc brake system with new front calipers; larger 10.5 US gal (40 L; 9 imp gal) fuel tank; upgraded heating and cooling system; revised front seats with an armrest and seat cushion; easy entry system designed into the driver's seats; revised steering wheel controls and revised steering; a Bose branded audio system as well as a more rounded center grille and a plastic lip that wraps onto the bottom of the spoiler. FCA offers the North American 500 with either a 6-speed automatic transmission with a driver-selectable mode as well as a 5-speed manual.[119]"

Just for comparison with the 500 images above, the familiar X caliper:

Obviously no way of knowing how the mounting bracket adapter would look unless you had all of the components on hand to take measurements. But it can't be any more complicated than the procedure PBS outlined in the "Project X1/9" book; use rear Lancia Beta rotors machined to fit axle flange, modify wheel spacers, modify Lancia caliper brackets, fabricate caliper mounting brackets and weld to modified Lancia brackets, use X calipers with Lancia pads. Sheesh!

 

[fiatfactory]

ATE brakes vs Bosch brakes... it looks like... some models of 500 use an ATE caliper that looks like the one listed in the rockauto catalogue.

http://www.ebay.it/itm/FIAT-NUOVA-5...348764?hash=item54058c87dc:g:USQAAMXQC-tTDyDo

I haven't done any work on a multiair 2 cylinder 900cc powered 500.... but it looks like those calipers possibly found their way onto the US spec car

SteveC

 

[Dr.Jeff]

Steve, I also see US spec Abarth 500 has calipers that "look" like the ones you referenced earlier (Bosch style), but I found them with Mopar P/N's:

The Abarth calipers are listed as 54mm, but I don't find a size spec for the standard 500 (US) caliper.

 

[BEEK]

vicks rotors are 239mm diameter v/s 257.3mm for the fiat 500

 

[Dr.Jeff]

Thanks Beek, that's interesting. I did not find any specs on their site but it read as though they use 500 components. Is this on your X? Maybe you can offer more images / details to enjoy?

I also noticed on Vick's site another image of the calipers included with Vick's Prima kit. These do not appear to have the wide mounting bolt locations as on the Abarth calipers (and I believe the Bosch Euro spec 500) * [Edit, see later post for correction]:

[Edited: Removed comment I made that was corrected in later post.]

One design feature I like when utilizing all components from a common application is they are known to be compatible with one another. For example the caliper / pad dimensions will be correct for the rotors (width, arc, thickness, etc). Not that other calipers won't be compatible, but it offers that much less development frustration when you know they are. [Assuming you get the adapter brackets to locate the calipers correctly.]

A consideration when designing the mounting adapters / brackets for the calipers would be completely replacing the stock "supports" rather than adding adapters between the stock support and the new caliper. By "support" I am referring to item #21 in this diagram:

That's what it looks like Allison did for the 124 kit with 500 calipers:

 

[motoTrooper]

On my Scorpion, I have fit the 500 Abarth front calipers to the stock front hubs and am working on the rears. The bolt spacing is the same but I had to enlarge the mounting holes on the hub. I have then measured and subsequently fitted a 260mm disc. I am waiting for some pads (ordered) to make sure I am right in all measurements. It was on my list of things to shoot for a video series that I am creating.

 

[Dr.Jeff]

MotoTrooper, that's excellent! I assume the calipers would need to be located further out (greater radius from center) in order to use the larger rotors? Please tell us more. The 500 rears was my next thought if the fronts worked out. Allison has a kit to put the 500 rears (like the fronts) on a 124, but I see nothing for the X rears.

I think I've found my confusion above. Looking at the Euro style / Bosch calipers (Mopar US Abarth) without it's standard bracket, the caliper appears to have very wide mounting locations. But seeing the complete caliper (with standard bracket) the mounts are the same narrower locations. These are the REAR (US spec) Abarth 500 calipers, but you can see both sets of holes...narrower below and wider above (better perspective). I was mistaking the pin's holes for the mounting bolt holes:

So the Vick's Prima calipers (like the yellow image from Vick's catalog, above) may be Euro spec 500 calipers. Perhaps smaller diameter rotors where chosen to keep them within the confines of the 13" wheel (as stated in the listing).
Thoughts?

 

[motoTrooper]

Nope, I temporarily mounted the driver-side caliper with smaller bolts and washers initially to figure out what radius the distance was before I ordered rotors. I have mounted 15" wheels as per my build thread (which we'll all have to rebuild when photobucket crashes from it financial death spiral)
https://xwebforums.com/forum/index....new-scorpion-owner-1553-restomod.28514/page-2
I happened upon a deal for some 260mm rotors so I grabbed them 270mm may be better but I gambled and will soon know when the pads come in.
The rear caliper bolt spacing doesn't match (smaller) so I will have to fab some adapters, I ordered some 257mm solid rear rotors so I can figure out those dimensions. Also the 500 mounts the rotors behind the hubs and our cars (the X1/9 and Scorp) have them mounted in front so the calipers need to be swapped side to side and the e-brake cable clevis(s) need re-clocking on the calipers.
I just decided to go my own way despite the arguments and will mount a pair of master cylinders and adjust them proportionately. I figure I'll work it out and regardless I'll have some good mechanical advantage with the larger rotors and modern calipers and rotors. And some spendy Hawk pads, let's not forget those.
Also I'm moving the fuel tank to the frunk so that'll help in theory...

 

[BEEK]

 

[phillips82]

As to the original post and the question about what is a direct fit or not...

No modern brakes are a direct fit. You're stuck with sliding wedge calipers and solid rotors.

Thanks to things like a CNC milling and 3D printing you can make anything work as long as you have the time to design it and money to make it. Our kit uses some spacers and adapter brackets and custom hoses. Could we make a "better" kit? You bet! Give me enough money and I'll put together a kit with a new spindle holding 4, opposing 8 piston calipers. Throw in another chunk of money and I'll design a new pedal box with quad master cylinders so you can dial in brake bias based on corner weight. What can be done is mainly based on money.

In case someone wants to mention how they built a brake kit for a nickle I will remind you that your time isn't really free. A nickle investment and 9000 man hours of work isn't the same as a nickle in my pocket.

 

[BEEK]

i appreciate the vendors who take the time to bring us great options for our vehicles. Could i make a bracket and adapt a caliper and rotor. sure can but they have done the research and taken the time to make an affordable kit.

Thanks.

 

[fiatfactory]

I think my Grande Punto S has the same brakes as the European 500 Abarth (without the brembo option)... mine runs 285mm discs up front and 257 discs on the rear...next time I have the wheels off and a caliper handy I'll check the mount spacing, but from what Mototrooper says they could well be the same spacing as the X19

Actually there are other varieties of pin mounted calipers that suit the same identical spacing as the run of the mill Bendix caliper and bracket, from the early/mid 80's there are a big bunch of models that actually used the very same stub axle/ hub as the X19, and they used pin mounted calipers, so no we are not stuck with a sliding wedge caliper at all. Most models only used a solid disc, but going up to a 257mm x 12 disc makes for a worthwhile upgrade and a decent increase in stopping ability ... anything from a ritmo/regata definitely does the job, fits straight on with zero mods except using a caliper banjo bolt with the correct thread pitch.

Quad master cylinders ...lol

SteveC

 

[Rupunzell]

Been discussed:
https://xwebforums.com/forum/index....rket-brakes-front-and-rear.25925/#post-216672

https://xwebforums.com/forum/index....rket-brakes-front-and-rear.25925/#post-215897


Definition of "upgrade" is key here. IMO, the stock brakes as delivered on the exxe is good, very good for real world road conditions including rain, snow-ice to warm sunny days. Given the ability of the stock power train, it is quite sufficient. What might bother some is the pedal effort which IMO, is absolutely fine and in many ways better than the far overly power assisted brakes on the modern production passenger car.

Most aftermarket brake kits focus on the front brakes, which are already prone to lock-up. Increasing the rotor diameter can reduce pedal effort, increased caliper piston diameter will reduce pedal effort trading off pedal travel. Once the brake pedal travel has been increased, the brake pedal position relative to the throttle pedal will change altering the ability to toe-heel (IMO, not acceptable in any way as the stock set for toe-heel is good). To properly modify the brake system on the exxe, it must be done as a system that considers not only rotor size, brake calipers, the modifications must take in consideration brake bias front to rear and brake pedal position during brake application. It is a complex system that should not be broken up into individual elements and tinkered without consideration for the whole.

One example of a proper brake system upgrade:
https://xwebforums.com/forum/index.php?threads/ultimate-brake-upgrade.32467/

The 74' went the Fiat Uno Turbo front brakes (48mm pistons identical to as stock exxe) and 38mm piston rear calipers from the Lancia Scorpiacarlo,Fiat 125, Fiat 132 and etc route. These are OEM Fiat, with all worn parts replaced and tested for proper function before install.
https://xwebforums.com/forum/index.php?threads/uno-turbo-front-caliper-install.31249/#post-262850

While this did NOT decrease brake pedal effort my much, the overall brake balance front -vs- rear is significantly improved with this 74' stopping a LOT better and increased heat capacity. Pedal travel is essentially much the same as stock, maybe a few mm more due to the 38mm rear pistons.


Bernice

 

[Rupunzell]

BTW, for those interested, have a set of Fiat Abarth 500 front brake calipers (Bosch) brackets with aero-craft spec hardware modified to fit stock exxe uprights with hosed made to fit. These were for the LeMons racer that did not work out. Will post pix if interested.


Bernice