Uno Turbo Front Caliper Install

ng_randolph said:
I don't know how much adjustment happens on a single brake application. For the adjusters to keep up with brake pad wear certainly does not take much, but to bring the piston out the appropriate distance after having been fully depressed could take quite a few cycles.
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I have put some miles on mine since I installed the rears, so it has been a while. I just haven't used the car for a couple weeks while I was working on the coolant tank, and the weather was not condusive. When I put it all back together yesterday, I checked the pedal feel with & without the eBrake engaged and it was pretty much the same. I only drove it a few miles over winding back roads & then a couple miles on a higher speed road, however I was not conscious of any drama-inducing pedal travel as before.
 
lookforjoe said:
I have put some miles on mine since I installed the rears, so it has been a while. I just haven't used the car for a couple weeks while I was working on the coolant tank, and the weather was not condusive. When I put it all back together yesterday, I checked the pedal feel with & without the eBrake engaged and it was pretty much the same. I only drove it a few miles over winding back roads & then a couple miles on a higher speed road, however I was not conscious of any drama-inducing pedal travel as before.
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As close as I think I can get. It is apparent that the rear brake pads are not adjusted to the disk. A gap of .023" on each side presents it's self with the hand brake off. No amount of pulling the hand brake or pumping the brake pedal decreases this space. With the hand brake applied the pedal is up further. I did bleed the rear brakes again and no bubbles were bled out. Facing the task of disassembling the calipers was looking dismal. I did try and manually adjust the pistons out but was not able to decrease the gap due to the slot and where it ends up each half turn of the caliper piston. Faced with this dilemma I decided to treat the problem and forget about resolving the cause. I made up .020" spacers and installed them. At this time I cannot see any changed in pedal height with the hand brake on or off. Getting somewhere finally. With the spacers installed a .006" clearance remains.
IMG_3737.JPG
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See pictures and thanks for the help.

TonyK.

Grimsby Ontario Canada.
 
TonyK said:
Getting somewhere finally. With the spacers installed a .006" clearance remains.[
See pictures and thanks for the help.
TonyK.
Grimsby Ontario Canada.
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Basically the equivalent of anti- chatter backings found on many setups

Nice work!!

Edit - did you also use EBC pads and rotors? Curious if that a is an additional constant between us
 
lookforjoe said:
Basically the equivalent of anti- chatter backings found on many setups

Nice work!!

Edit - did you also use EBC pads and rotors? Curious if that a is an additional constant between us
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No, rotors are from Car Quest along with the brake pads.

TonyK.

Grimsby Ontario Canada.
 
That's a bit weird Tony, it suggests the self-adjustment mechanism isn't working. It further suggests you will have to add more shims as the pads wear!
 
TonyK said:
As close as I think I can get. It is apparent that the rear brake pads are not adjusted to the disk. A gap of .023" on each side presents it's self with the hand brake off. No amount of pulling the hand brake or pumping the brake pedal decreases this space. With the hand brake applied the pedal is up further. I did bleed the rear brakes again and no bubbles were bled out. Facing the task of disassembling the calipers was looking dismal. I did try and manually adjust the pistons out but was not able to decrease the gap due to the slot and where it ends up each half turn of the caliper piston. Faced with this dilemma I decided to treat the problem and forget about resolving the cause. I made up .020" spacers and installed them. At this time I cannot see any changed in pedal height with the hand brake on or off. Getting somewhere finally. With the spacers installed a .006" clearance remains.View attachment 2277 View attachment 2278 View attachment 2279 View attachment 2280

See pictures and thanks for the help.

TonyK.

Grimsby Ontario Canada.
Click to expand...

If you have any used pads, maybe pop them in and see if the self adjusting system just needs more "throw" to function?
 
Dan Sarandrea (Phila) said:
If you have any used pads, maybe pop them in and see if the self adjusting system just needs more "throw" to function?
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All good suggestions. The simple fact is that both rear brakes are doing the same thing. Driving out the wedges and the caliper is sitting there and flopping around, never seen that before. I am wondering if the hand brake lever on the caliper is retracting enough. The hand brake does not come up as high as it used to prior to the install. I also considered installing used pads, I know I have them here. Then there is the shimming question, should I make up more to add in when the pedal gets lower? I could try and change the self adjusters out of an old set of 34 MM calipers and see where that takes me as well.

Thanks for the comments.


TonyK.

Grimsby Ontario Canada.
 
0.023" gap between the pad backing and caliper is huge. 0.005" range is typical. Could the rotors be warped or not running true? Put a dial indicator on the rotors, check their run out, typically in the 0.003" range. If the rotor run out is excessive and the self adjusters in the rear calipers are not functioning properly, these problem need to be corrected before braking assignment can be made. The brake pads could be non-uniform thickness between the backing plate and pad friction material. Given the questionable CCO of parts today most anything problem is possible. Removing the rear calipers, taking them apart to assess what the problem could be appears to be a given as the shims are not going to compensate for pads wear. If the pistons do not self adjust, the gap might increase with pad wear making this aggravating this problem.

If rear calipers for parts are needed, got more than a few of the 34mm piston or stock variety. Be happy to send them to you as needed.


Bernice
 
probably a timely reminder on the internal workings of the rear caliper adjuster... a good cutaway presentation can be found here (thank you Bjorn if you drew this up - great work)

What goes wrong with the self adjuster, is the spring 'tail' snaps off so the whole spring rotates (the red part in the drawing) this is pretty obvious but I don't think this is the problem with Tony's calipers... I have also seen the spring slipping on the 'nut' (blue part in the drawing) ... obviously it is supposed to slip in one direction, as it turns the coil is being unwound and loosened so allowing the nut to move and adjust.. but in the other direction the spring should wind tighter onto the nut, and prevent rotation (adjusters backing off) I have seen the springs damaged and spread so they wouldn't grip in one direction... and think something like this is the issue internally in this case.

I don't know why people are so put off by the disassembly and reconditioning of these rear calipers... if you make a simple tool it becomes very easy... My tool is made from a modified Vee block clamp, which fits into the groove that holds the rear dust boot on...that's how the factory tool for the job functions...and then a modified socket that allows the wedge to be slid into place while the belville washers are compressed.

https://www.google.com.au/search?q=...2jj9HTAhWLv7wKHUaqADwQ7AkIMw&biw=1536&bih=798

SteveC
 
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Rupunzell said:
0.023" gap between the pad backing and caliper is huge. 0.005" range is typical. Could the rotors be warped or not running true? Put a dial indicator on the rotors, check their run out, typically in the 0.003" range. If the rotor run out is excessive and the self adjusters in the rear calipers are not functioning properly, these problem need to be corrected before braking assignment can be made. The brake pads could be non-uniform thickness between the backing plate and pad friction material. Given the questionable CCO of parts today most anything problem is possible. Removing the rear calipers, taking them apart to assess what the problem could be appears to be a given as the shims are not going to compensate for pads wear. If the pistons do not self adjust, the gap might increase with pad wear making this aggravating this problem.

If rear calipers for parts are needed, got more than a few of the 34mm piston or stock variety. Be happy to send them to you as needed.


Bernice
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Thanks for the offer Bernice, I should be okay for now. I have a lot going on in my personal life that is consuming my time. Had septic problems which have me shovelling most of the weekend to find a settled main line plugged. That is fixed but the front yard is a mess. My son is getting married at the end of the month, then there is a stag party this Friday night. My 40th anniversary is coming up in June and I trip to Fiji for 2 weeks, then FFO 2017. Now that I know what the problem is and I have it under control I will deal with it.

So to be clear that clearance of .023" is static without driving the car down the road. When I brought the car into the shop and removed the wedges the calipers were flopping around. I then put the calipers back on the car and the hand brake holds the disk doesn't matter how much pumping or hand brake I use .023" is the return spring clearance. Again possibly the nut is not turning and locking in the piston or the springs are just too strong and draw the piston back. The rotors are the same as was on the car with the stock Fiat calipers so if it was the rotors then I should have had this problem before. .003" of rotor run out is huge and the pedal would be pulsating this was not the case.

The week after the wedding Bob Martin will be here and I have the week off and will be working on his car. If I have time I will pull the rear calipers and disassemble the rear pistons. At least I have Bob to help me bleed the brakes which is a big help from doing it alone. For now I can drive the car without being afraid the pedal is too soft.

Thanks for the replies.


TonyK.

Grimsby Ontario Canada.
 
fiatfactory said:
I don't know why people are so put off by the disassembly and reconditioning of these rear calipers... if you make a simple tool it becomes very easy... My tool is made from a modified Vee block clamp, which fits into the groove that holds the rear dust boot on...that's how the factory tool for the job functions...and then a modified socket that allows the wedge to be slid into place while the belville washers are compressed.

https://www.google.com.au/search?q=...2jj9HTAhWLv7wKHUaqADwQ7AkIMw&biw=1536&bih=798

SteveC
Click to expand...

Do you have a pic of the tool in use? I'm trying to visualize it. Where is the wedge?

Piston_assy_zpsb7ba1698.jpg
 
TonyK said:
A few pictures of what you request. I think I have the problem figured out
TonyK.
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I assume this is what you did to compress the Belleville springs when removing the parking brake shaft and pawl. In your setup you are applying pressure to the piston, which is dicey. You risk doing damage to the self adjuster mechanism.

I do this only after the piston has been removed (or before it has been reinstalled). This is from when I rebuilt the calipers a few years ago:

DSCN1175.JPG
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I had to modify the C-clamp a bit to get it to fit at the back end of the hand brake plunger. I think I got the idea from this post by Yves. His photos show the C-clamp modification more clearly than mine.
 
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Modified C-clamp or similar tool should be used to install the manual brake (E or Parking brake) lever. Know there are two bushings pressed into the aluminum casting. These steel bushings are bearings for the lever. If too much side force is applied while the lever rod is installed, the bushings will be knocked out of place causing a significant problem. If the bushings are scored or damaged during installation, the lever can and will hang up causing a different set of problems.

The lever is not difficult to install with the proper tool and understanding of how it all works and what conditions are mandatory.


Bernice
 
lookforjoe said:
Where is the wedge?
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The wedge that fits into the hand brake plunger shaft rounded groove (at the top of the grey shaft), and also fit's into the groove in the handbrake lever's shaft (which pushes thru the two bushed holes)... that transmits the rotary force of the hand brake lever to a linear force in the hand brake plunger. (not shown in the above pic)

Tool is made from a vee block clamp like this
clamp.jpeg

but with a semi circular plate welded to the 'feet' which slips snugly into the handbrake boot groove in the caliper body, a steel sleeve like the one Tony has pictured
IMG_3726.JPG
(which I made from an old socket) gets pushed on by the screw thread... well the Vee block clamp I used has a swivel foot (like a G clamp has) which pushes on the back of the sleeve...to compress the belville washers and allow the handbrake shaft and wedge to be inserted. I just copied the factory too which I saw a picture of... no juggling with things in a vice or damaging anything.

SteveC
 
Like most things in the car, it is self evident once you actually have it apart - looking at Yves' (linked) pics with the parts laid out I can see how the mechanism operates - I've never had one apart or even removed the boot to inspect. I can see now what you mean (SteveC) about clamping in the groove so that the load is not on the piston.
 
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fiatfactory said:
The wedge that fits into the hand brake plunger shaft rounded groove (at the top of the grey shaft), and also fit's into the groove in the handbrake lever's shaft (which pushes thru the two bushed holes)... that transmits the rotary force of the hand brake lever to a linear force in the hand brake plunger. (not shown in the above pic)

Tool is made from a vee block clamp like this
View attachment 2303
but with a semi circular plate welded to the 'feet' which slips snugly into the handbrake boot groove in the caliper body, a steel sleeve like the one Tony has pictured
View attachment 2304
(which I made from an old socket) gets pushed on by the screw thread... well the Vee block clamp I used has a swivel foot (like a G clamp has) which pushes on the back of the sleeve...to compress the belville washers and allow the handbrake shaft and wedge to be inserted. I just copied the factory too which I saw a picture of... no juggling with things in a vice or damaging anything.

SteveC
Click to expand...


Okay the pictures of compressing the spring washers on the old seized caliper piston in the vise was to remove the springs to see if I could swap them out. Normally I remove the piston first then compress the springs with a section of flat stock across the caliper body.

The problem is LASH. Sadly these calipers have a piston made from cold rolled steel, not plated nor finished. Surface imperfections are apparent and they will rust. This leaves me to either remove them and send them out for finishing and plating or make new pistons from Stainless steel stock. The self adjusting mechanism uses a 4 start threaded rod rather than a 5 start threaded rod like OEM. That .023" or more return clearance is the lash between the nut and the rod threads. The solution of adding the shim works and should continue to work for self adjustment. Another solution is to remove the self adjuster from the OEM piston and install it into this caliper. For now I really don't feel like removing the aftermarket calipers as the shims should work for the time being. I could find thicker sheet to decrease the lash even more.

Here is a picture of the internals of the self adjuster. I removed the piston from the caliper on the car and took it apart for investigation. I did not pull the wedge and cam out to look at the threaded rod.

TonyK.

Grimsby Ontario Canada

IMG_3745.JPG
 
Tony, thanks for the investigations. I will have to pull mine & check the lash/play on my calipers. You have posted two of the same pic, and since there is a threaded rod in it, I have to assume this is the layout of a stoock caliper?

very saddening to hear they used untreated mild steel for the piston, that is not good at all :(
 
I think we have established that the rear calipers that both Tony and Hussein purchased were from the same supplier....in the interest of full disclosure could you guys name names so that folks can make an informed decision if they are in the market for the 38mm rear calipers?
 
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