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Tii Vs Volvo Caliper Question


bnam
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While looking at this picture in another post, it struck me that the reason the volvo calipers accommodate vented disks is because the "nubs" in the circled areas are machined down widening the opening vs. those on the Tii caliper.  So, can one achieve the same result by machining the Tii caliper?

 

img2769e_zpsbb377590.jpg

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I agree.  But, I was trying to understand if there was more to it.  I have a Tii, so is machining the calipers a viable way to get vented discs.  And for standard 2002, could one machine that as well to get vented discs?  Or are there other differences.  Perhaps Volvo pistons are bigger or have more clamping power?

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Interesting idea. Hard to know if the structural rigidity would be compromised, as all the meat would have to come off of the outer nubs. The 528i calipers (E12) for the 2002tii vented conversion simply add a spacer between the two tii halves to get the width. One could wonder if BMW considered just machining the nubs as suggested, but decided not for either safety or cost reasons. The spacers and O-rings are likely cheaper than machining already made parts. So another idea is to put together a spacer, O-ring, and longer bolt kit. Some people say never split the calipers, but I have done it before and don't see why not. But fabricating a nice flat spacer to the right dimensions is likely more hassle than getting just 528i calipers when using tii struts.

 

--Fred '69 & '74tii (both with vented rotors)

Edited by FB73tii
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I don't think the nub is structural, but I think I now see what could be the real issue -- if the nub were machined off, the disc brake slot would be nearly flush with the outer pistons.  It would not have the space that the Volvo pistons have --where it slot looks like it had the nubs machined off, but there still is a gap to the pistons.  

 

More reason why a spacer would have be needed.

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no, Byas has it right- the room is all needed for pad thickness and the nubs are critical to hold the

backing pads in place- those nubs transfer the load from the brake pad to the caliper.  That's 

quite a bit of load.

 

And yes, you can find spacers (and bolts) to widen the tii caliper, AND some of the Volvo/528 calipers

(but oddly, not all) are done that way.

 

t

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W+N does sell complete parts to widen tii calipers. Not really cheap though if all prices added up.

 

Some Volvo models had same type of calipers for non-vented, solid rotors (at least EURO). Those are a bit smaller. But it seems Volvo didn´t go the way with the spacers - caliper halfs machined differently.

 

For tii strut it might work out with late E12 calipers. From 76 on dimensions on caliper halfs were changed and thicker brake pads were mounted in E12. If you take a late E12 caliper for solid rotors and fit it on tii strut with the thinner tii brake pads there might be enough room to install a vented disc. Never tried myself though. Maybe vented disc isn´t centered then.

 

Best regards, Lars.

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