| Author |
Message |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1111
Registered: 2-2001
| | Posted on Thursday, April 18, 2002 - 7:11 pm: | |
Humans are not perfect, that is why there are shims and funnels. Most cars built today have no front end alignment provisions either. They are made right to start with and should not change unless something gets bent. |
magoo (Magoo)
Advanced Member
Username: Magoo
Post Number: 2507
Registered: 2-2001
| | Posted on Thursday, April 18, 2002 - 5:10 pm: | |
Now guys this was my question. Is it that the shims are necessary to cover up sloppy workmanship or are the shims there to provide more accuracy and precision? Which one would it be? |
Jeff 77 GTB (Jbk)
Junior Member
Username: Jbk
Post Number: 76
Registered: 4-2001
| | Posted on Thursday, April 18, 2002 - 11:41 am: | |
As with everything else, you get what you pay for. Mercedes and Volvo make it right the first time and you see it reflected in the price of the car.... oh wait, we're talking about F cars here. Never mind. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1104
Registered: 2-2001
| | Posted on Thursday, April 18, 2002 - 11:05 am: | |
Mercedes and Volvo use the same system as Ferrari and Jaguar and no shims. They make it right the first time. |
Steve Magnusson (91tr)
Member
Username: 91tr
Post Number: 677
Registered: 1-2001
| | Posted on Thursday, April 18, 2002 - 8:42 am: | |
I have to disagree about shims being "crude" -- I'd much rather have a fixed brake caliper design requiring shims than the more usual sloppy floating brake caliper design that didn't need shims. "Inacurrate" is also too harsh IMO -- they're called "tolerances". |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1101
Registered: 2-2001
| | Posted on Thursday, April 18, 2002 - 5:41 am: | |
Ford has helped. They are using mostly GM parts on Jaguars now. It's true. |
magoo (Magoo)
Intermediate Member
Username: Magoo
Post Number: 2477
Registered: 2-2001
| | Posted on Wednesday, April 17, 2002 - 9:15 pm: | |
I guess Ford has helped out a great deal. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1099
Registered: 2-2001
| | Posted on Wednesday, April 17, 2002 - 9:00 pm: | |
Absolutely, Jaguar is just as crude as Ferrari. They are getting better though. |
Bill Sebestyen (Bill308)
Junior Member
Username: Bill308
Post Number: 160
Registered: 5-2001
| | Posted on Wednesday, April 17, 2002 - 8:54 pm: | |
When I removed my calipers, shims dropped and went everywhere. Now mind you, this was not the first time someone had worked on these calipers. I basically replaced the shims to center the caliper over the disk and selected shims to orient the caliper with the plane of the disk, by eye. I did not have a matched set of shims, because I checked their thicknesses with a micrometer. Some had rust on them, but were ok to use, after I cleaned them on a flat surface with fine abrasive paper and lightly coated them with anti-seize. There is at least one caliper with an extra shim in it, but alignment looks good by eye. By the way, if you every rebuild the calipers, be sure to orient the notch in the pistons properly. |
magoo (Magoo)
Intermediate Member
Username: Magoo
Post Number: 2471
Registered: 2-2001
| | Posted on Wednesday, April 17, 2002 - 8:48 pm: | |
Ed, Your statement regarding inaccurate machining makes me wonder if Jaq uses the same shim set up is their problem inaccurate machining also? |
Steve Magnusson (91tr)
Member
Username: 91tr
Post Number: 675
Registered: 1-2001
| | Posted on Wednesday, April 17, 2002 - 6:30 pm: | |
Mitchell -- Sorry, I misunderstood your earlier message. I thought you meant 3 of the calipers have only 1 shim at each mounting point (which would be OK) - 1 shim only one one mounting point does seem odd. |
Mitchell Minh Le (Yelcab1)
Junior Member
Username: Yelcab1
Post Number: 125
Registered: 11-2001
| | Posted on Wednesday, April 17, 2002 - 5:53 pm: | |
That is what I mean, each caliper has 2 mounting points each with one shim. And in my case, 3 calipers only have one shim on one mounting point, the other shim on the other mounting point is gone. |
Steve Magnusson (91tr)
Member
Username: 91tr
Post Number: 674
Registered: 1-2001
| | Posted on Wednesday, April 17, 2002 - 4:40 pm: | |
Mitchell -- there's no requirement to have two shims in each position. As long as each caliper has the same amount of shims at the two mounting points and the disk is roughly centered in the caliper all is OK. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1090
Registered: 2-2001
| | Posted on Wednesday, April 17, 2002 - 4:17 pm: | |
The only reason for the shims is due to the inaccurate machining of the entire system. Plain and simple. |
Mitchell Minh Le (Yelcab1)
Junior Member
Username: Yelcab1
Post Number: 124
Registered: 11-2001
| | Posted on Wednesday, April 17, 2002 - 1:02 pm: | |
My calipers (this is the first time i took them off) are like this:
1. 3 calipers have only one shim for each caliper, not two
2. 1 caliper has two shims but of different thickness.
So, I have to conclude that the bonehead who did this before just lost some of the shims and did not care enough to get replacement, and just put them back. I guess I better get some new ones now. |
magoo (Magoo)
Intermediate Member
Username: Magoo
Post Number: 2461
Registered: 2-2001
| | Posted on Wednesday, April 17, 2002 - 11:15 am: | |
Sounds like overkill but if it works I guess thats all that matters. Does it align the pad to the rotor better under heavy brake application? There must be a reason for getting the pads precisely aligned. |
Jeff 77 GTB (Jbk)
Junior Member
Username: Jbk
Post Number: 72
Registered: 4-2001
| | Posted on Wednesday, April 17, 2002 - 6:34 am: | |
I believe when I removed my calipers the thin shim was between the caliper and hub, and the thicker shim was under the head of the attachment bolts. Maybe it was the other way around, but they both were not between the caliper and hub. The parts diagram shows them separate as well. Which ever ones center the rotor in the caliper properly should be the correct ones. Just make sure you use the same thickness for both attachment points. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1086
Registered: 2-2001
| | Posted on Wednesday, April 17, 2002 - 5:29 am: | |
Jaguar also uses them. |
magoo (Magoo)
Intermediate Member
Username: Magoo
Post Number: 2442
Registered: 2-2001
| | Posted on Tuesday, April 16, 2002 - 10:56 pm: | |
Shims, Is Ferrari alone in this setup? |
Verell Boaen (Verell)
Junior Member
Username: Verell
Post Number: 85
Registered: 5-2001
| | Posted on Tuesday, April 16, 2002 - 10:41 pm: | |
Mitchell,
My car has a thick/thin shim pair per caliper bolt. Both front calipers seem to have identical pairs, so I believe that the hub & caliper tolerences must be pretty good.
See my post under the following thread for the EASY way to deal with the shims & some other 308 brake service tips:
"Euro 308 QV Brake..."
http://server.ferrarichat.com/~ferrari/ferrarichat.com/discus/messages/112/4360.html
I just used my eyeball & a steel scale to verify that the rotor was centered in the caliper opening. Just measure the gap on each side of the rotor at the top & bottom of the caliper. It's probably more important that the top & bottom gaps on the same side are equal than it is for the front & rear gaps be the same. (ie: The caliper must be parallel to the rotor, but being slightly (off-center by a few mm is not as critical.)
Good luck, this is one of the easiest service jobs once you know how to deal with the #$\% shims. |
Steve Magnusson (91tr)
Member
Username: 91tr
Post Number: 672
Registered: 1-2001
| | Posted on Tuesday, April 16, 2002 - 10:06 am: | |
Mitchell -- don't panic. The feeler gauge stuff is for setting the rear pad -to- rotor spacing. Centering the disc within the caliper itself is not that critical (and can just be eyeballed) -- all you're trying to do is make sure that when (new) pads of equal thickness are installed that the opposing pistons roughly protrude the same amount from the caliper housing. It's more important that you don't mix-up the shims and have different total shim thicknesses under the 2 mounting bolts (which would mess up the parallelism between the piston faces and the rotor surfaces). |
Mitchell Minh Le (Yelcab1)
Junior Member
Username: Yelcab1
Post Number: 123
Registered: 11-2001
| | Posted on Tuesday, April 16, 2002 - 9:53 am: | |
OK,
So now I am in a little trouble. Can someone provide some specifications as well as procedure? I do have
1. factory workshop manual
2. feeler guages
3. enough wrenches to fill a garage
Do I remove the brake pads to get a better view of the caliper piston for measurements? |
Steve Magnusson (91tr)
Member
Username: 91tr
Post Number: 670
Registered: 1-2001
| | Posted on Tuesday, April 16, 2002 - 9:29 am: | |
Mitchell -- the purpose of the shims is to (roughly) center the disc within the (fixed) caliper opening. Also, the ends of the caliper pistons should be parallel to the disc surfaces so I think you should make sure that the total thickness of shims is the same under the 2 mounting bolts for each caliper (and that the mounting surfaces and shims are "clean" when reassembled). |
Mark C. Gordon (Markg)
Junior Member
Username: Markg
Post Number: 164
Registered: 2-2001
| | Posted on Tuesday, April 16, 2002 - 9:23 am: | |
Yes, the factroy has clearence tolerances between the caliper, pads and rotors; you need a feeler gauge and factory specs to set caliper spacing correctly. |
Mitchell Minh Le (Yelcab1)
Junior Member
Username: Yelcab1
Post Number: 122
Registered: 11-2001
| | Posted on Tuesday, April 16, 2002 - 9:05 am: | |
I was taking off the brake calipers and I notice that there are shims (one or two) of different thickness between the caliper arms and the mounting on the hub. FIrst time I see that.
Other than being a b@#$H to put back, what are they for? To align the caliper to the hub? If so, I am afraid I may not have put all of them back in the right positions. |