Raybestos ST43 Front Brembo pad slop

[hsteel]

Installing some ST43 (that I purchased from a member on here) into the GT PP brembos. There is noticeable slop when the pad is in the caliper. The bad plate of the pad is smaller by ~2.5mm. Is this normal or do I have the wrong pads? The pads appear to have ST43R1291T16 on them, which when I search comes back as a Mercedes’ pad. The pad shape is close, but not identical

 

[thelostotter]

My ST43 and ST45 pads are more sloppy than the stock pads. I just measured the ST45, they are 7.375" in length.

Do you have the box? They should be RC1792 or AP1792 pattern. Porterfield could also probably confirm for you if you are unsure.

 

[hsteel]

Thanks for the measurement. Mine are the exact same 7.375". Are yours also missing the "ears" with the square cutout in?

The box does say RC1792, but there is no mention of 1792 on the back of the pads. The profile of the pad is identical everywhere else but the length and ears. It is interesting that it calls out the pad length as 7.469" on Porterfield. I will try giving them a call.

Should I be pulling the shim off my stock pads and running it on the back of these? Or did your pads come with the shim?

 

[thelostotter]

Thanks for the measurement. Mine are the exact same 7.375". Are yours also missing the "ears" with the square cutout in?

The box does say RC1792, but there is no mention of 1792 on the back of the pads. The profile of the pad is identical everywhere else but the length and ears. It is interesting that it calls out the pad length as 7.469" on Porterfield. I will try giving them a call.

Should I be pulling the shim off my stock pads and running it on the back of these? Or did your pads come with the shim?

They did not come with shims but I do run titanium shims with them.

 

[hsteel]

Thank you very much for the information. Looks to be the exact same back plate profile. I guess I will give them a go!

 

[JAJ]

My ST43 and ST45 pads are more sloppy than the stock pads. I just measured the ST45, they are 7.375" in length.

Do you have the box? They should be RC1792 or AP1792 pattern. Porterfield could also probably confirm for you if you are unsure.

I got curious about this information exchange about brake pads so I did some digging. My understanding is that the GT350 and the GTPP pads are the same width - 189.7 mm - and just a different depth. But 7.375" wide is only 187.3 mm, which is 2.4 mm (roughly 3/32") shorter than spec. I looked at Pagid Racing and at Porterfield and the only pads I could find in that size range were all 189-ish mm pads (no 187-ish pads). So, yes the pads in the photos are smaller than spec. That may be on purpose to make them easier to change or something. Thing is, I have 189.7 mm race pads from different manufacturers stacked up in my garage, and none of them are that sloppy a fit. I'd contact the supplier and ask them what's going on. If they'd been shipped to me, I'd have rejected them as defects.

 

[thelostotter]

Good point. I just went and measured my stock PP pads and they are 7.475" which is actually a little larger than the 189.7mm spec shown for the RC1792.

I've had a set of ST45 on backorder at Porterfield since November, I'll reach out with this finding and see what they say.

 

[hsteel]

Called Porterfield. Turns out they are modifying a Raybestos pad to work for our application. This is the longest pad that Raybestos makes, so the slop, while it isn't meant to be there to this extent, is to be expected.

In the future, these pads will come with no markings on the back and only the box will be labelled RC1792. If you have issues with these pads, call Porterfield directly, as they are technically no longer a Raybestos (at least by design) pad.

The people at Porterfield were very helpful. Quality customer service!

 

[thelostotter]

Called Porterfield. Turns out they are modifying a Raybestos pad to work for our application. This is the longest pad that Raybestos makes, so the slop, while it isn't meant to be there to this extent, is to be expected.

In the future, these pads will come with no markings on the back and only the box will be labelled RC1792. If you have issues with these pads, call Porterfield directly, as they are technically no longer a Raybestos (at least by design) pad.

The people at Porterfield were very helpful. Quality customer service!

Wendy just emailed me back and she said the same thing. Interesting. It appears we are getting Mercedes pads modified for our calipers, based on what you dug up in the OP.

 

[hsteel]

Wendy just emailed me back and she said the same thing. Interesting. It appears we are getting Mercedes pads modified for our calipers, based on what you dug up in the OP.

I am kind of surprised this kind of information is only just coming to light! I feel more comfortable about running the pads now at least

 

[JAJ]

I am kind of surprised this kind of information is only just coming to light! I feel more comfortable about running the pads now at least

So, if you're going to run them, check that the end of the pad makes full contact against the inside of the pad pocket. Looking at the setup from the side, you're most concerned about the upper edge of the pad, since the rotor is rising and pushing the pads upward as it passes through the caliper. If the pad can't reach the side of the pocket because the retaining pins are stopping it from going that far, running them could damage the caliper. The pins are there to keep the pads from falling out - they're not really intended to take the full side-load of a 1 G stop. The load bearing part of the caliper is the side of the pad pocket and it can take that kind of load all day long.

On the other hand, if the pad is snug against the end of the pocket and it's slack on the pins, it'll probably be a bit noisy, but it should otherwise work ok.

 

[KazarS197]

I keep reading through this thread and keep going - What?!? There are 2 different things here. The pad material size ( it's important but not as important as the back plate size) and the backing plate size (It needs to be the spec size to prevent movement in the caliper) I attached a photo of what the measurements of the backing plate should be ( borrowed from Pagid) I also did some research on the Mercedes pad - the back plate is also supposed to be 189mm. From my eyes the back plate on the Raybestos Product is completely wrong. When I'm driving a 3500lb vehicle 130+ MPH and braking down to 70 MPH I am going to make sure the things slowing my Mustang down are fitting perfect. Just me - If I received those pads and they were off by 2.4-5 mm I'd be irritated and feel I didn't get what I paid for, would get a refund and go in a different direction. I defiantly don't want something banging around in my calipers. They are aluminum - who know if continued hitting in the slot will eventually open the slot to where no pads fit correctly - will that result in a need to replace the calipers. I have 6 piston PP G-Loc and EBC pads and both measure OEM spec and back plates are the exact shape as OEM. Just my 2 cents.

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[JAJ]

Found it!!! Didn't use the find pads by size search the first time. Here's the pad spec that was delivered:



The issue of whether it'll work properly is still open, but at least it's not a manufacturing defect. It's just a different spec than Ford's spec.

 

[KazarS197]

Found it!!! Didn't use the find pads by size search the first time. Here's the pad spec that was delivered:

View attachment 75655

The issue of whether it'll work properly is still open, but at least it's not a manufacturing defect. It's just a different spec than Ford's spec.

Yes. It's a spec size pad. The question is which vehicle application is it really used for. It's not matching Ford or Mercedes. They are trying to retrofit a different pad size to Ford instead of using the correct Ford back plate and manufacturing a pad. The statement " .... longest pad Raybestos makes...". Is what sits bad with me. It's like indirectly admitting it's not correct.....

 

[TWF]

I keep reading through this thread and keep going - What?!? There are 2 different things here. The pad material size ( it's important but not as important as the back plate size) and the backing plate size (It needs to be the spec size to prevent movement in the caliper) I attached a photo of what the measurements of the backing plate should be ( borrowed from Pagid) I also did some research on the Mercedes pad - the back plate is also supposed to be 189mm. From my eyes the back plate on the Raybestos Product is completely wrong. When I'm driving a 3500lb vehicle 130+ MPH and braking down to 70 MPH I am going to make sure the things slowing my Mustang down are fitting perfect. Just me - If I received those pads and they were off by 2.4-5 mm I'd be irritated and feel I didn't get what I paid for, would get a refund and go in a different direction. I defiantly don't want something banging around in my calipers. They are aluminum - who know if continued hitting in the slot will eventually open the slot to where no pads fit correctly - will that result in a need to replace the calipers. I have 6

Yep, plate needs to be exact fit. Not only it will wear out caliper but pins as well. With that much play pins are probably only thing holding them and all braking force going in to pins.
No way I would use those.

 

[hsteel]

So the pad doesn't rest against either end of the caliper. It sits central held in position by the spring, which is held by the guide pins. This does seem like a lot of stress to put on those pins.

On the other hand there does seem to be a number of people running these on the forum. I am surprised no one has ran into issues.

 

[JAJ]

So the pad doesn't rest against either end of the caliper. It sits central held in position by the spring, which is held by the guide pins. This does seem like a lot of stress to put on those pins.

On the other hand there does seem to be a number of people running these on the forum. I am surprised no one has ran into issues.

Yes, it's a lot of stress for the pins. If you take the spring out, does the pad reach the end of the pocket? There's enough force on the pad under braking that any positioning effect from the spring is overcome and the pad will move as far as it can.

 

[hsteel]

Yes, it's a lot of stress for the pins. If you take the spring out, does the pad reach the end of the pocket? There's enough force on the pad under braking that any positioning effect from the spring is overcome and the pad will move as far as it can.

Without the spring and calipers loosened off, the pad can move freely up and down