1974 Tii front brake identification

[VeroTii]

Forum members,

The front brakes on my recently purchased 74 Tii are dragging slightly.  Pads and rotors look fine.  The car has been sitting a long time so I believe it is time for a caliper rebuild.  The problem is, I do not think the calipers are stock.  The rotors are vented.  The car has had lots of "typical" upgrades over the years and I am wondering whether they could be 320i calipers and rotors.  I want to buy the right rebuilt kit before pulling them off.  The stamping on the outboard housing is "71G" and the pads are marked "M4" (see pics).  Can anyone help me identify what I have?  Thanks.

[stephers]

They are probably from a big 6 car       5, 6 or 7 series from late 70's                I will double check with some calipers that I have on my shelf at the shop later      Check with Realoem on the piston size, I think that you may find that they are all the same size       

 

Thanks, Rick

[VeroTii]

Thanks.  I have looked for other markings but cannot readily see any.  One would think there would be a part number stamped somewhere.  Any help is appreciated.

[Son of Marty]

I'd take Ricks advice, almost sure to be big 6 calipers and later ones I think, as there is no spacer between the 2 sections and fit the 3.5 inch mounting ears and are branded ATE. Pull the pads and put a caliper across the piston.

[JohnS]

Do you know whether your "tii" still has the big bearing struts on it or not?  The stock tii spindles?  That's important

[VeroTii]

Don't know what is original but I will start researching what is there.  I believe the car had a pretty thorough restoration in the early 2002's where many upgrades were done (moved battery to the back, strut braces front and rear, brake upgrades, MSD ignition, Bilstiens, larger radiator, etc.).

[Mikesmalaga72]

2002 Tii rotors are 256MM diameter by13MM Tii thick

320I rotors      are 255MM diameter  by 12.7 MM  

2002 rotors     are 240 MM diameter by 10MM

[TobyB]

It's hard to tell from your pictures.

We need a bit farther pulled back, showing the whole thing.

Also, they are drilled.  Are they also vented to the center eye?

 

Those are not 320 parts, nor are they 320 rotors.

The only vented rotors that fit those earlier hubs are Turbo rotors, afaik-

everything else uses the later hubs.  However, I don't see the rotor retaining

bolts that hold the rotor to the hub...

 

They could be 5er or 6er calipers- they are not the latest version, though, 

as they are 2 circuit.  At the end of production, before going to a sliding

caliper, the big cars went to a single circuit front 4- pot.

Realoem.com does not do a good job of showing this, saying they went straight

to a sliding single caliper.

 

There are never part numbers cast into BMW parts.  The castings are 

used to make multiple parts, depending on machining, so any number

you find on castings are internally identifying the casting, or the casting date,

but doesn't ever directly number the part itself.  That caliper's a perfect example-

as a later 6er, it's 34111119021

but with a different spacer it's 34111101095 on the E12 5 series or a tii.

Same casting.

 

More pictures will help a lot.  I suspect you have turbo (or other early) rotors with a 

5 or 6 series caliper.

 

t

 

[2002iii]

4 hours ago, VeroTii said:

The rotors are vented.

I think you mean drillled.

2 hours ago, Son of Marty said:

I'd take Ricks advice, almost sure to be big 6 calipers and later ones I think, as there is no spacer between the 2 sections and fit the 3.5 inch mounting ears and are branded ATE. Pull the pads and put a caliper across the piston.

I don't think I've ever seen vented calipers without a spacer, got any pictures?

 

 

2 hours ago, JohnS said:

Do you know whether your "tii" still has the big bearing struts on it or not?  The stock tii spindles?  That's important

The e12 5/6 calipers will only fit on tii struts.

 

I think they might just be tii calipers with drillled rotors.

[bergie33]

I agree with @2002iii.  I think the rotors are drilled and not vented. Meaning stock tii pads and rotors. The dragging is probably sticking pistons. 

[Son of Marty]

Ah I see what your getting at. Does your rotor edge look like this picture or are you refering to the drilled holes?

[VeroTii]

Apologies to all.  They are drilled not vented.  I will take the group advice, pull the wheel again and take some measurements.  It is possible that the rotors were bad at some point and were replaced with aftermarket drilled ones.  The calipers are possibly original but I will measure the pistons.

[Mikesmalaga72]

Tii brake caliper pistons 40MM diameter, rebuild kit for calipers per side

 

ATE Brake Caliper Repair Kit; Front part number  34111158692 

Edited May 6, 2023 by Mikesmalaga72

[VeroTii]

All,

Thanks again for your help.  The drilled rotors measure out at 256MM diameter and 13MM thick.  The mounting ears are 3.5 inches.  Stock for a Tii apparently.  I don't want to pull the calipers to measure the pistons until I am ready to do the job but am going to assume at this point that my calipers are original.  Attached are a couple more pictures for those who requested better views.

As another thought, the flexible brake lines are stainless mesh (obviously not stock) but pretty old.  Do they go bad often enough for me to consider replacing them while I am in there?  I don't want to spend for no reason but always want things right.  Any thoughts/experiences are appreciated.

[TobyB]

Is there a thin spacer on the face of that hub?

 

There are usually 4 recesses for the inhex (Allen) bolts that hold the rotor to the hub.

 

But yeah, I think you'll be safe to order stock caliper parts for the rebuild.  The tii was

(afaik) the only car that used that rotor unvented. 

 

t