Brake disc specs?

[hanknum]

No one knows the min thickness? Anyways, I had some rear rotors that I'm putting on the front, turned down to 25.05mm thickness. Looks like they still have plenty of meat on them.

Another quick question I(MLAUTO)... Does anyone know if there are any compatible rotors that are larger than the 310mm?

Thanks,

Henry

 

[ML Auto]

The only rotors that are similar thickness are Cobalt SS rotors with the Brembo calipers, and they are only 315mm rotors. The hub center needs to be enlarged to work. I did one set but didn't think it was worth the effort over the 308mm Saab rotors that fit right on.

The min rotor thickness should be 24mm, which is what the Lotus is.

 

[hanknum]

The only rotors that are similar thickness are Cobalt SS rotors with the Brembo calipers, and they are only 315mm rotors. The hub center needs to be enlarged to work. I did one set but didn't think it was worth the effort over the 308mm Saab rotors that fit right on.

The min rotor thickness should be 24mm, which is what the Lotus is.

Thanks ML... knew you'd know. Yeah, I'd have to agree, I don't think having to bore out the hub center would be worth the additional 2.5mm in brake radius torque.

I figured that I was safe with it turned down to 25mm... but, it is interesting that at that thickness, the material removed went down below the chamfer on the drilled holes.

 

[jnordeng]

The Saab 9-5 Aero also came with 321mm discs

 

[ML Auto]

The Saab 9-5 Aero also came with 321mm discs

They are 28mm thick, Just the 9-3 has the 25mm ones

 

[hanknum]

OK, here's something interesting. I installed a left rear rotor on the left front. I installed 5mm spacers under the caliper mounts to account for the larger rotor, AND I replaced the OEM pads with the Carbotech AX6 pads. Now the pads outer edge extends about 2mm past the edge of the rotor. Apparently, the friction material of the Carbotech pads are positioned further out from the center than OEM. I like how it goes all the way to the edge (and over) to increase brake torque, but losing a bit of swept area of the pad. I will try a thinner spacer, but have to keep in mind the clearance of the caliper with the edge of the rotor.

One thing to keep in mind is is the Carbotech pad material has a much higher C of F than the used OEM pads... at least to my unscientific finger tips. On initial bite, it also much more aggressive.

I'll try and post some photos later.

 

[hcsharp]

One thing to keep in mind is is the Carbotech pad material has a much higher C of F than the used OEM pads... at least to my unscientific finger tips. On initial bite, it also much more aggressive.

I'm using AX6 pads and I agree on the much greater C of F. They're not so good when the weather gets cold but you don't have to worry about that in sunny So Cal LOL. Next time I might try the 1521s. They're even better with titaniumdave's rotors but I like the idea of increasing the diameter.

 

[hanknum]

I'm using AX6 pads and I agree on the much greater C of F. They're not so good when the weather gets cold but you don't have to worry about that in sunny So Cal LOL. Next time I might try the 1521s. They're even better with titaniumdave's rotors but I like the idea of increasing the diameter.

Hi Henry,

Yeah, if I lived in a colder climate, I'd consider the 1521's... don't think I have much to worry about here in Santa Barbara. It seems like EBC pads are getting popular now.

I thought about TitaniumDave's rotors, but decided they were a bit too rich for my blood. My mods are the budget upgrade. I should be getting my new 4mm spacers on Thursday and will give a final evaluation afterwards.

Henry, lmk when you come to SB... we got to get together (I mean after the CV-19)

 

[hanknum]

Here's a couple pictures. The first is the positioning of the friction material of the OEM pad to the Carbotech pad on the right. The second picture is the finished product... 310mm rear rotor, rear wheel (on the front), Carbotech AX6 pads, and yellow painted caliper. I will have more detailed pix as I do the other side.

 

[drewski]

Here's a couple pictures. The first is the positioning of the friction material of the OEM pad to the Carbotech pad on the right. The second picture is the finished product... 310mm rear rotor, rear wheel (on the front), Carbotech AX6 pads, and yellow painted caliper. I will have more detailed pix as I do the other side.View attachment 527990 View attachment 527992

Looks good!

Does the regular front wheel clear the caliper & disc? Or was using the rear wheel needed for clearance?

And did you paint the caliper yourself?

 

[hanknum]

Thanks Drew. I'm not sure if the OEM front will fit, but pretty sure that it will... I'll check and get back to you.

Yes, the caliper paint was something I bought off of Amazon. It is a brush on and actually looks real good. It is glossy and very comparable to powder coating. If you want, I can find the brand for you.

 

[drewski]

Thanks Drew. I'm not sure if the OEM front will fit, but pretty sure that it will... I'll check and get back to you.

Yes, the caliper paint was something I bought off of Amazon. It is a brush on and actually looks real good. It is glossy and very comparable to powder coating. If you want, I can find the brand for you.

that would be great - both front wheel fit & caliper paint. did it come with two colors or you got both black & yellow?

 

[hanknum]

that would be great - both front wheel fit & caliper paint. did it come with two colors or you got both black & yellow?

Here's the paint info. I did not need black... the black is just the natural color of the caliper. Also, I'll check the fitment of the OEM front later today.
https://www.amazon.com/gp/product/B00XKTU2ZQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[hanknum]

Yep, the OEM front will fit w/o any issues.

Also, a couple more of the finished right side... note the tight clearance between the caliper and rotor.

 

[drewski]

Yep, the OEM front will fit w/o any issues.

Also, a couple more of the finished right side... note the tight clearance between the caliper and rotor.View attachment 528906 View attachment 528907 View attachment 528908 View attachment 528909 View attachment 528910

cool, thanks!

that's with a 5mm spacer or did you decrease the spacer to get more pad contact?

 

[hanknum]

I went with a thinner spacer... 3.7mm. The caliper clears by about 0.5mm or 0.025" and the top of the pad just extends above the rotor about the same. I found a place on ebay that advertised 4mm washers, but said their tolerance was +/- 0.4mm. A bag of 10 was $5 delivered. So I ended up with a range and was able to pick and choose which ones fitted best.

BTW, the painting was a piece of cake. Other than masking off the "AP racing" part, you can be pretty careless, because the rotor hides the back of the caliper, and you only view it from the top anyways.

Painting the rears now... though I've never been a fan of painted sliding calipers. It's one step away from the people who paint their whole brake drums... if you have drums, i don't think you want to draw a whole lot of attention to those.

 

[hanknum]

Getting some brake noise... does anyone know what is best to use? I've got some lube, but the old pads were glued on with some adhesive.

 

[titaniumdave]

I have adhesive I have been supplying with my pad/rotor sets available plus .5 mm shims for the caliper radial mount bolts if those would help with fit up. Did you put in longer bolts for radial caliper mounting?

 

[hanknum]

I have adhesive I have been supplying with my pad/rotor sets available plus .5 mm shims for the caliper radial mount bolts if those would help with fit up. Did you put in longer bolts for radial caliper mounting?

Hi Dave,

I did not use longer bolts... I checked and IIRC, they threaded in 13 - 14 turns, which came out to 1.4 - 1.5 times the diameter.

A couple things that I'm a bit concerned with...

- After bedding in the pads per Carbotech (multiple hard stops, and multiple moderate stops), I noticed a lip on the outer front rotors. I did not expect that. It is not huge, but it is noticeable. There is definitely more bite with these, but I'd hate to eat through the rotors that quick.

- The rear pads had some sort of pin cast into the back plates of the pads. There was one on each pad and it was not centered. If I installed like that, the pads would be slightly angled. I decided to file each of them down so that they would be flush with the piston. I also reused the thin plates that were glued to the rear pads... not sure if I needed to or should have.

Lmk what you think.

Thanks.

 

[titaniumdave]

Hi Dave,

I did not use longer bolts... I checked and IIRC, they threaded in 13 - 14 turns, which came out to 1.4 - 1.5 times the diameter.

A couple things that I'm a bit concerned with...

- After bedding in the pads per Carbotech (multiple hard stops, and multiple moderate stops), I noticed a lip on the outer front rotors. I did not expect that. It is not huge, but it is noticeable. There is definitely more bite with these, but I'd hate to eat through the rotors that quick.

- The rear pads had some sort of pin cast into the back plates of the pads. There was one on each pad and it was not centered. If I installed like that, the pads would be slightly angled. I decided to file each of them down so that they would be flush with the piston. I also reused the thin plates that were glued to the rear pads... not sure if I needed to or should have.

Lmk what you think.

Thanks.

I go with 2 diameters for the bolt engagement, I have 75mm bolts I had made for a big rotor kit I made for Lotus Elise/Exige cars if you want longer bolts for peace of mind.

Don't worry about a little overhang on the pad going past the outside diameter of the rotor, it's pretty normal for these cars.

The rear calipers are a single piston with a sliding bracket, it's common for manufactures to create a wedge shape on the backing pad to counteract the tendency for the pads to wear in a wedge shape. This allows the pad to wear down to the back plate with consistent pad material.