[tyl604]

Guys - installed a new brake caliper and rotor turns freely. Put the wheel back on and cannot rotate wheel - at least by hand. This is the second caliper - first one did the same thing so I took it back.

But I am wondering - is it necessary to bleed the brakes first and get some brake fluid in the caliper for it to work? And for the wheel to turn by hand? Is that maybe all I need to do?

PS - this is for my Mercedes but assume answer is same for most any vehicle.

 

[redtruck12]

Is this a front or rear caliper?
If it is a rear, there may be an alignment piñon the back of the pad that needs to line up with the groove in the piston ( assuming it is a piston actuated e brake)
Bleeding should not come into play at this point.

 

[tyl604]

Good thought but no. Is front left side - driver side. Is it possible that I may not have it torqued enough? Say only 70 instead of 85 - and if I torque it to 85 it would pull the outbound side of the caliper in enough to clear? I see no way that there could be that much give - but wondering. With wheel off the rotor moves freely so it is not binding there.

I am more thinking that Mercedes changed the design slightly during that model year and the parts guys did not know it. Ie wrong caliper. But I have measured it every way from Sunday and see absolutely no difference.

 

[Chubbs878]

Good thought but no. Is front left side - driver side. Is it possible that I may not have it torqued enough? Say only 70 instead of 85 - and if I torque it to 85 it would pull the outbound side of the caliper in enough to clear? I see no way that there could be that much give - but wondering. With wheel off the rotor moves freely so it is not binding there.

I am more thinking that Mercedes changed the design slightly during that model year and the parts guys did not know it. Ie wrong caliper. But I have measured it every way from Sunday and see absolutely no difference.

Pull up a tech guide or service manual and double check that you installed the parts properly. i have never had anything like that happen before on brake service of various vehicles.

 

[tyl604]

Yes, I actually printed off the entire process and studied it. There is no way to install it improperly. It is wheel specific and has only two bolts which connect it to the vehicle. It fits, brake pads go in great, and it works until you bolt on the wheel; then it binds on the wheel.

I am convinced that Mercedes had another stock number caliper for my car and Pep Boys agrees and is finding the caliper. Will see if it looks any differerent. In fact it is so easy to install, that I will just pop it on for grins and try it. If, of course, they actually find one with this mysterious new parts number.

I am now also convinced that torquing it down more will not give enough clearance to make a difference. I have not pushed in any brake fluid but that would not make a difference; the caliper is wide open now and the brake pads are slightly clear of the rotor.

 

[redtruck12]

Are you also replacing the rotors? Could it be a rotor fit issue? What is hitting /rubbing when it is all assembled?

 

[number9]

Have you used a light and inspection mirror to see WTF is preventing rotation?
......

 

[gurunutkins]

what type of mercedes? for eg. if you mistakenly fitted the brake calipers for a w210 e320 wagon to a w210 e320 sedan the calipers will hit the standard 10 spoke wheel and jam the wheel - remove the wheel and everything spins freely. Mercedes in particular is very touchy on the caliper sizes particularly for the more modern series (after 1996).
If everything is spinning freely before the wheel goes on then it pretty much has to be interference of some sort. Did you compare the old calipers to the new? have you checked part numbers on the EPC at startek.com they ask for a credit card number bu US addresses get yearly access to the Mercedes database for free and if you enter your vin the part numbers it kicks out will be correct.
just some thoughts
cheers
Barri

 

[gurunutkins]

just looked at the pictures again and making the assumption that one is the new one (cleaner) - it may be me but whilst they appear to be identical one is actually a mirror image of the other so one looks like the left and the other the right? can you put in a picture of one on top of - or rather above -the other with the bolt holes on the same side rather than comparing them side to side and then look at the hollow where the rotor runs.
cheers
Barri

 

[gurunutkins]

Im going to stop playing now - but put one above the other as in the new compilation from your pics then whilst they look the same next to each other put like this with the bolt holes on the same side they are actually mirror images of each other.
time to switch off
cheers
Barri

 

[PTSchram]

When dealing with ANYTHING Mercedes (or German for that matter) it is critical to use the VIN to get the correct part.

Mercedes (and most German manufacturers) are VERY specific about when changes were made. If they say it was up to 2000-01-01, you can damn well bet a car made on 2001-01-02 had the different part.

When specifying which coil springs (as a crazy example) to order, the MB factory parts catalog assigns a point to silly things like whether the car has a CD player or cassette player!

I was astounded to learn this when I was a parts manager for an indy import shop.

 

[tyl604]

Vehicle is 1981 300SD and I am original owner. Yes, I ordered by VIN number and double checked by using Mercedes parts number too.

The calipers are side specific and cannot be switched. I took photos and then turned both calipers over and took more pics.

There is not enough clearance inside to see with the naked eye what is touching; the caliper is very close to the wheel at the back and you cannot see down inside what is touching in the front. However from the scratch marks on the wheel I am convinced that the tip of the caliper itself is touching when lug bolts are installed.

Rotor turns fine but the tire and wheel do not feel right when I hoist them up and the bolt holes do not match like they should. Lug bolts go in but do not feel right and when tightened the wheel will no longer turn.

Am going to jack up the other side and look. Please confirm that it cannot just be that I am torqued low - say 70 compared to spec of 85. I will never believe that some additional torque could make the difference.

 

[gurunutkins]

Am going to jack up the other side and look. Please confirm that it cannot just be that I am torqued low - say 70 compared to spec of 85. I will never believe that some additional torque could make the difference.

No you are right - torque from 70ft lbs to 85 ft lbs will not make a difference in this instance. Check that there is not grit, metal burrs or similar between the caliper to knuckle mating face. Mercedes calipers generally fit very closely to maximum space in the wheel rim so the smallest thing can throw them off.
good luck
Barri

 

[tyl604]

Resolved

Hurrah; it is resolved. It was the jackstand. I had it too close to the wheel. When I put the wheel back on, it hit the jackstand and went catywampus. As soon as I tested this by moving it back, the wheel went on perfectly and in three minutes I was ready to bleed.

All done and good brakes now.

Thanks for the help.

 

[redtruck12]

Ha ha ha
Bet you feel a little silly on this one!
Glad you got it figured out

 

[tyl604]

Worse than silly.


Arrgh.

 

[redtruck12]

I guess experience has a lot of value