38mm Piston Rear brake Caliper install

Discussion in 'Workshop Forum' started by Rupunzell, Oct 29, 2016.

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  1. Rupunzell

    Rupunzell Bernice Loui

    Location:
    California
    These started out as a pair of rear calipers from a 76' Lancia Scorpion.
    Quite icky directly from the Lancia. They were washed in an industrial hot water & soap washer then abrasive particle blast cleaned. This is what the brackets look like after being primed with Tempo zinc phosphate primer (the aircraft stuff out of a rattle can). The M10x1.25 x 20mm long socket head cap screws were painted at the same time and they masked off the threaded holes.
    [​IMG]

    Same applied to the brake calipers:
    [​IMG]

    Calipers were rebuilt with new seals, boots and all. Krytox was used as assembly lube for the pistons. Swepco 101 was used on the outer parking brake wedge lever. There are the finished brackets and calipers installed with new EBC rotors (painted black as delivered).
    [​IMG]

    EBC green pads installed:
    [​IMG]

    The Facom brake piston expander tool, works good:
    [​IMG]

    New calipers, EBC rotors and Green pads done:
    [​IMG]

    Top view:
    [​IMG]


    Air purge from the brake calipers then took the exxe out to bed the new pads. Brakes have better front to rear balance so far. I'll know more once the new pads have settled with more driving. If needed, the front limiter valve can be adjusted to tweak in the from to rear brake bias.


    Bernice
     
  2. lookforjoe

    lookforjoe True Classic

    Very nice! Are these Hen's Teeth, or can they be sourced as reman units? Are they applicable to other models that would make a search easier?
     
  3. kmead

    kmead Old enough to know better

    Location:
    Michigan
    They are usually available rebuilt on European ebay sites, generally as Fiat 125 units as I recall they are the same. Pretty certain a seller in Germany usually has them.

    Do check the application as my memory could well be faulty...
     
  4. Rupunzell

    Rupunzell Bernice Loui

    Location:
    California
  5. lookforjoe

    lookforjoe True Classic

    That's funny - I messaged Mr. Fiat about those, and his reply was that he thought they were stock - since it doesn't mention piston od I was hesitant. Knowing the pn's for the 38mm piston version helps :)

    Edit: To clarify- the stock slider and rotors work with these, or do I need different parts for those. It's not specified in the main post....

    EDIT - did a qucik search using the casting # from the first post - 4249992 - seems all brackets are the same, so depth of the caliper ears for the wider pads must be the only change (in addition to the piston of course). Correct me if I'm mistaken.
     
    Last edited: Oct 31, 2016
  6. fiatfactory

    fiatfactory Steve Cecchele

    Location:
    Western Australia
    34mm piston calipers have 124 cast into the body and a fiat part number... 38mm calipers have 125 cast into the body and a fiat part number.

    Fitted to Fiat 125 (all models) Fiat 132 (those models with disc brake rear) and Lancia Beta Montecarlo/Scorpion...

    Those calipers from mrFiat look to be reconditioned... I can see lots of pitting on the alloy body.

    The calipers from Chris Obert that Bernice pointed to are new... he also stocks reconditioned 38mm ones
    http://www.fiatplus.com/RT-R-CALIPER-141.75-CORE.html
    http://www.fiatplus.com/LT-REAR-CALIPER-141.75-CORE.html
    at $85 a side plus a $100 core charge

    SteveC
     
  7. lookforjoe

    lookforjoe True Classic

    His listings are confusing. The first one you referenced from Rachel's post, also says $100 core charge, so it is unlikely that they are new although 299 per is rather steep? Dunno.

    The remans end up being more than those from MrFiat with the core charge factored in, esp. with shipping costs cross-country, I tend to only buy lighter weight items from them, as their adjusted shipping costs can be steep to NY.
     
    Last edited: Oct 31, 2016
  8. ArtBasement

    ArtBasement Erwin Timmers

    Location:
    DC
    Some questions...

    I have to rebuild the rear calipers on mine, as they started to leak with pitted pistons. Very tough to find new 38mm pistons. I'm taking your write up as my guide.
    Questions: How come the discs are black? Is that a paint? Does that come off?
    You didn't use any pad springs. Is there an advantage I'm missing?
    I thought the scribed line on the piston face had to be up to help the bleeding. Did you turn the piston 180 deg after pic?
     
  9. lookforjoe

    lookforjoe True Classic

    Ordered the calipers from MrFiat, and EBCpads/rotors from JCWitney :) I hope they help with the larger wheels/tires...
     
  10. Rupunzell

    Rupunzell Bernice Loui

    Location:
    California
    More road time on the revised brake caliper set up, works GOOD.

    If the front calipers are 54mm pistons with a stock 3/4" master, the brake pedal will be slightly lower due to the increased volume of brake fluid required by the 38mm pistons in the rear calipers.


    Bernice
     
  11. Rupunzell

    Rupunzell Bernice Loui

    Location:
    California
    Do a search on line to see if any brake parts suppliers in the EU, UK and else where have replacement pistons for these 38mm rear caliper. If the chrome to base metal pitting is not severe, it is possible to have the chrome plating removed, pits lapped smooth then re-chrome plated (not your typical re-chorme plating shop job).

    The EBC rotors arrived painted black. I'm guessing this is their way of preventing near instant rusting of cast iron rotors without using a petro based product. The paint wears off quick and acts as a brake pad to rotor seating indicator.

    The anti-rattle springs/clips did not fit with the EBC pads, so they did not get installed. There are two styles of anti-rattle springs, one that sits along the length of the brake pad, the other is a clip at on the ear of the brake pad. They are intended to take up the gap between bake pad baking and caliper bracket preventing them from knocking when the pads engage the rotor. If the pad backing is a snug fit, these anti-rattle springs are not needed to prevent the pads from knocking when the pads engage the rotors.

    Brake caliper piston slot sits horizontal parallel to the road surface. In theory, they self-adjusting manual brake mechanism will function fine either direction, difficulty with the slot sitting vertical is installing the brake pads as the pads have a bump on the steel backing that engages the slot allowing the self-adjuster to work.


    Bernice

     
  12. ArtBasement

    ArtBasement Erwin Timmers

    Location:
    DC
    Thanks for your feedback. The pits were pretty deep. I found new pistons from www.biggred.co.uk. These are not OEM, but are newly machined. Just arrived today. 1 week from UK, not bad.

    It may help the delay rust on the surfaces that are not in contact with the pads. Do you think it will delay bedding in time?

    Gotcha

    I meant the machined line just parallel to the slot. It indicates the side where the back of the piston has some relief machined into it, making it easier to bleed. On my new piston this relief is negligible, but on the OEM FIAT pistons it is more substantial. Wondering if it even matters...

    So where do you use caliper grease when you put the caliper together? Can this be on the piston where it touches brake fluid? or just where the piston pokes through the seal, under the dust boot? I've never used grease before when putting a caliper together, just brake fluid.
     
  13. Rupunzell

    Rupunzell Bernice Loui

    Location:
    California
    Good to hear replacement pistons were found. Like many items Fiat, what was officially imported to the US market was limited in many ways. Given the ability to use the web, world wide shipping and ability to move funds, finding and purchasing bits from else where is easier today in many ways.

    That paint on EBC rotors comes off in nothing flat, has nil effect on initial pad seating at all. It does help to give some indication of how the pads are meeting the rotor initially, but once the pads have gotten happy with the rotors, none of this matters at all.

    As for the line, don't think it will make much if any difference at all.


    Bernice



     
  14. TonyK

    TonyK True Classic

    Location:
    Grimsby Ont Canada
    Ordered Calipers

    I ordered rear calipers from Mr. Fiat, looking at the add again I cannot say if they are 124 calipers or 125 calipers. I have sent an email and see what the reply is.

    TonyK.

    Grimsby Ontario Canada.
     
  15. lookforjoe

    lookforjoe True Classic

    Mine arrived yesterday - they are both and new castings. Piston appears to be 38mm,based on measuring the seal area. I can take pics Tomorrow- when I emailed him, he didn't know if they were stock size or no. I assumed larger, since they also list an x1/9-124 caliper....
     
  16. TonyK

    TonyK True Classic

    Location:
    Grimsby Ont Canada
    Casting number

    What is the prefix casting number 125 or 124?

    You will have to remove the dust seal and push the piston out a bit to take a measurement. I certainly hope Mr. Fiat knows as much about these calipers as we do.

    Looking on other sites they all want the old calipers sent back.
    Three years ago the Canadian dollar was 3 cents higher than the US dollar.

    Currently that is not the case and the calipers selling for $349 plus shipping to Kentucky is $495 CND.

    I did explore modifying for installation Mini Cooper combination Calipers but they appear only to be 36MM pistons and VW Passat which has 41 MM pistons. The big issue is the manual brake cable location which appear to be correct for our use. The X uses leading calipers like the cars above but many manufactures use calipers installed on the trailing side of the wheel disk which causes the hand brake mech. to be unsuitable for the X. The time required to modify installation is why chose Mr.Fiat's listing. Still not sure if he has it right.


    TonyK.

    Grimsby Ontario Canada.
     
  17. myronx19

    myronx19 True Classic

    Location:
    Toronto, ON Canada
    Black Rotors

    Do you think that's paint?

    I would have guessed E-coat or black zinc, but not paint. Coated rotors are a nice idea - I can't stand rust trailing off the hats. :)
     
  18. lookforjoe

    lookforjoe True Classic

    They only have the Fiat PN's that Bernice listed - 418971 & 418972, there is no other marking.
     
  19. lookforjoe

    lookforjoe True Classic

    Installed my calipers yesterday - however I found I ordered EBC front pads :( I'll have to put new rear pads in next week. If anyone wants EBC front green pads cheap, LMK[​IMG][​IMG]'][​IMG]']
     
    Last edited: Nov 21, 2016
  20. kmead

    kmead Old enough to know better

    Location:
    Michigan
    So does it take the same rear pads as an X or are they the pads used on a Scorpion/125? Or?
     

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