From Rebuilding and Splitting an ATE Brake Caliper I'm guessing the same as the rear. This is for Ate, so Bendix might be different.

 

Thanks the rears were done to 25llb/ft but unable to find front bendix torque

 

If ti's the same bolt (diameter and thread) in the same application than the same torque should be fine. It depends more on the bolt and application (shear vs. tension) than anything else.

 

bolts on te rear caliper take a 10mm socket and are thinner the front calipers take a 17mm socket but told by two brake companies to thighten front and rear bolts the same to 35 to 40nm which is what i did

 

bolts on te rear caliper take a 10mm socket and are thinner the front calipers take a 17mm socket

Don't make the mistake of confusing the socket size with the bolt size. What matters is the diameter of the shank of the bolt.

It says if there is leaking then torque is incorrect,

I agree if it leaks (with new o-rings) then the torque is not correct, but if it doesn't leak that doesn't mean it's right. When you apply the brakes the pistons try to force the halves apart. The torque (tension) on the bolt has to be enough that the hydraulic force cannot make the halves separate. The total pressure exerted by the pistons (psi x area) has to be less than the tension in the bolts (psi x cross sectional area x number of bolts)

 

Here is the PDF on rebuilding Teves Bendix front calipers from my MBCDs.

They go at it entirely differently apparently.. special tools & all....

MBL

 

thanks couldnt see any torque settings it says not to seperate,will see how i get on once plumbed in
It says if there is leaking then torque is incorrect, i put new o rings between the calipers and they were raised slightly before joining the calipers together

 

The bolt size is much thicker on the front than the rear i have been trying to find this torque figure for the front and told by a brake company the torque figures are the same for front and back

 

Can you give me the diameter and thread pitch of the bolt? Are there any markings on the head of the bolt, like 10.9?

 

the bolt says 11.9 on it, diameter is 9.85mm, i dont know the pitch but will try put up a pic approximately threads are 1mm apart

 

the bolt says 11.9 on it, diameter is 9.85mm...

Well, sounds like you have a 10mm bolt there. I've heard of grade 10.9 and grade 12.9, but never 11.9. Are you sure? Common thread pitches are 1.25 and 1.5, so, since you're estimating 1.0, most likely yours are 1.25. Can't make a recommendation, though, without knowing the grade.

 

 

You'll need to put a thread pitch gauge on it for true accuracy.

They usually reside in any METRIC Tap & Die set... Perhaps even, a local hardware store or European auto repair shop local to you.

Hang in, and stay safe!

M

 

OK, I did a little research. European markings are a little different than SAE markings. Bolts could be made to an 11.9 spec if the manufacturer wanted them to be. The appropriate torque would be slightly less than midway between 10.9 and 12.9. Those bolts were cad plated when new, but the plating has worn off, so, my recommendation would be to oil the threads with engine oil (don't get any in the brake cylinders themselves) and torque them to about 50 ft-lbs or 68 Nm.

 

Hi so I made a post about the torque specs for the rear caliper bolts on my 97 E420. I separated them to remove/install new pistons and seals but wasn’t aware that I wasn’t supposed to split the calipers. The bolts say 11.9 so should I apply red loctite and torque to at least 40 foot pounds like you mentioned? And also are each caliper half the same for the rears? Because when I split them I mixed them up if that makes sense.

 

I will have a look at the bolt again i had them shotblasted then plated so possibly 10.9
50 sounds a fair bit
If i bolt them to the car can i toruqe them then prob is u used threadlock at 25 do i need to open and clean all the bolts again

 

If you had them plated then the torque is different (more, actually). I suggested oiling them to eliminate variables, but if they're newly plated then they should be installed dry. Liquid thread locker probably puts you back in the same ballpark as oiled.

25 ft-lb is way to low for a 10mm bolt loaded in tension. The tension in the bolt has to be greater then the hydraulic force trying to push the halves apart. If they're 10.9 then about 45 would be good.

 

Ok thanks will do 45 calipers willl
Be going on in 5 weeks can i just nip upto 45llb/ft or do i need to undo the bolts clean and then tighten

 

Do they have Loctite on them? If so, you have to break them loose before you can retorque them. What I would do is remove one bolt. Clean the loctite off with acetone and swab the threaded holes out with a q-tip soaked in acetone. When it's dry, apply new loctite and reinstall it with 25 ft-lbs if that's what you used before. Then, repeat with the other bolt. Torque that one to 45, then torque the first one to 45. If you're concerned, use 40 ft-lbs, but I wouldn't go lower than that.

 

Do you mean one bolt at a time

 

Do you mean one bolt at a time[?]

Yes. Isn't the caliper back on the car? You don't want to split it again, do you? Just don't let anyone push on the brake pedal while you have any bolts out...

 

The big difference between left and right is where the fluid inlet is and where the bleeder is. When the caliper is mounted the bleeder should be up and the hose down. Start there and work your way though. The side with the mounting ears may be the same left and right.

I would not use red loctite. Blue is more than enough.

If you've split them you need to replace any seals between the two halves

 

Ok thank you, and I have all of the the crossover seals that seal the fluid passage inside the caliper but they’re flat due to them being inside the caliper a while. They didn’t leak at all even with them being flat, should I run them again or should I find the same size seal brand new maybe from a hardware store and install them?

 

Sounds like you're saying they are original. The likelihood of them all working correctly second time around is pretty low.

I'm assuming you split the caliper to overhaul it. Didn't the overhaul kit include the o-rings? If you have to buy them separately, make sure you get EPDM rubber, unless you're using DOT 5 (silicone) fluid, in which case you need silicone rubber seals. I doubt you will find either one at a hardware store.

If it was not your intention to overhaul the caliper, but, especially if you've pushed the pistons out of the housing, you are sort of committed now.

 

Yeah they’re completely original, I don’t think they’ve ever been split before I did it unfortunately. And yeah I split the calipers to overhaul them, new pistons, seals, brake lines and brake fluid but I didn’t know that the rear calipers had crossover seals (small o rings) that I had to make sure were in place. And unfortunately the caliper repair kit didn’t come with them I guess because some manufacturers don’t sell them like regular brake parts?? And I’m using DOT 4 so no issues there, genuine Mercedes fluid too. And yeah you’re right!, the car was sitting for so long so I don’t mind a full overhaul it’s just some parts are hard to find or NLA which makes things trickier.

 

https://www.theoringstore.com/store/index.php?main_page=index&cPath=368_2278 You'll probably have to buy about 15, but they're only about 15 cents each. The shipping will probably be more than the o-rings.

Is there a recess in one half of the housing for the o-ring, and a flat, flush surface on the other half? Measure the OD and the depth of the recess. Find a cross section (CS) about 1/3 larger than the depth of the recess. Multiply that by 2 and subtract the result from the OD of the recess to get the ID of the o-ring. Your resultant OD should be about the same as the OD of the recess, and the depth of the recess should be about 75% of the CS.

 

Thank you for the site, that’s a huge help!! And yes there is but I only have a caliper tool that can measure the width of things I don’t think it’s the right tool to measure the depth of anything. Would I get an incorrect reading if I measure the old o ring? Also thank you for letting me know how to measure everything to get the right size!!

 

I don’t think it’s the right tool to measure the depth of anything.

Does your caliper have a little pointy thing (depth blade) that extends out the end when you open the jaws? If so, that's for depth.

You could measure the thickness of the old one, but bear in mind that the new one won't be flattened, so your measurement will be short. If you measure it the other way, cross section OD minus ID, your measurement will be too big. Maybe average the two? Either way, there are a finite number of CS measurements available, so, hopefully, the best one will be obvious. (Also, if you measure the ID of the old o-ring, it will be smaller than when new.)

[Edit] Oh, if your housings are recessed on both halves for the o-ring you need to measure the depth of both sides and add them together.

 

Ok thank you, I just saw that the caliper has a way to measure depth with the skinny pointy thing that comes out of the back of the caliper once you move it. And ok I’m guessing it wouldn’t read like a newer o ring would due to age and the amount of wear it has now? And I’m doing the measurements now, the only thing I’m confused about is finding the cross section that measures about 1/3 larger than the depth of the recess. Other than that I think I’m doing pretty good on measurements right now!!