Cracked rear brake rotor

[redvettx2]

So SPF 1639 had a brake squeal when I got it. On the list to sort out. It is only at very very light brake pressure that she wails. Car only has 2500 miles on it previous owner already had spent $800 for new pads. Crazy but with safety wiring the wheels up proper there is time involved which adds to the cost. Upon closer inspection on the rear rotors the passenger rear has surface cracking. Thats is what is doing all the screaming. Shop says we could machine them down and see what they look like. I just think at high temps sketchy rotors are never a good combo. I am more inclined to replace both the rears just to be safe. Recommendations? Upgrades? These should just be Wildwood correct?

[eschaider]

Your car should use OEM Ford rotors from an '89 - 92 Thunderbird. The forum has a 39KB speed limit on pdf documents, and the SPF document is 477 KB, so I can't post the document. If you would like a pdf copy send me a private message with your email.

[Mark IV]

1639 should be a Wilwood rotor, not a T-Bird.

[patrickt]

Originally Posted by redvettx2

...previous owner already had spent $800 for new pads. Crazy but with safety wiring the wheels...

That doesn't make any sense to me at all. Popping new pads in is easy. Safety wiring wheels is really easy. Surface cracks on rotors can be nothing or it can require new rotors. Rear rotors last longer than front rotors. You have to actually see it to know though. If it were me, two new Wilwood rotors are going to cost maybe around $500 for parts, so if the cracks bothered me I'd just replace them and put them on myself. But, I'm not going to say that to you after seeing a $800 bill from a mechanic just to pop in a set of pads. If for some reason mechanics are seeing your car and thinking "well I'll just price this rotor replacement job as if I had to drop an XKE's rear in the shop (even if I don't)" then there is something I'm really missing. Does your SPF not allow for on-car brake lathes? If so, I would go ahead and grind them and if the rotors are new looking and within specs I would think that would be just fine. Rear rotors can be a bit of a PITA to pull but I don't know SPF cars well enough to tell you how much. My ERA has six pin hubs back on the rear so it makes for a different job, but I don't think you have that issue so I won't belabor it.

[Mark IV]

Originally Posted by patrickt

That doesn't make any sense to me at all. Popping new pads in is easy. Safety wiring wheels is really easy. Surface cracks on rotors can be nothing or it can require new rotors. Rear rotors last longer than front rotors. You have to actually see it to know though. If it were me, two new Wilwood rotors are going to cost maybe around $500 for parts, so if the cracks bothered me I'd just replace them and put them on myself. But, I'm not going to say that to you after seeing a $800 bill from a mechanic just to pop in a set of pads. If for some reason mechanics are seeing your car and thinking "well I'll just price this rotor replacement job as if I had to drop an XKE's rear in the shop (even if I don't)" then there is something I'm really missing. Does your SPF not allow for on-car brake lathes? If so, I would go ahead and grind them and if the rotors are new looking and within specs I would think that would be just fine. Rear rotors can be a bit of a PITA to pull but I don't know SPF cars well enough to tell you how much. My ERA has six pin hubs back on the rear so it makes for a different job, but I don't think you have that issue so I won't belabor it.

We would never "grind" rotors, on car of off car, rotors from the last 20 plus years do not take well to machining. The new Wilwood rotors are not expensive ($60-70) and as you lose mass, you reduce the thermal absorption capacity of the rotor thus increasing the chances of warping/cracking, etc.

[patrickt]

Originally Posted by Mark IV

We would never "grind" rotors, on car of off car, rotors from the last 20 plus years do not take well to machining. The new Wilwood rotors are not expensive ($60-70) and as you lose mass, you reduce the thermal absorption capacity of the rotor thus increasing the chances of warping/cracking, etc.

Well that's shockingly cheap. Anything unusual or tricky to popping the rear rotors off on an SPF?

[Mark IV]

Originally Posted by patrickt

Well that's shockingly cheap. Anything unusual or tricky to popping the rear rotors off on an SPF?

Nope. Remove wheel, move the caliper, remove the adaptor and drive pins and go to it!

[patrickt]

Originally Posted by Mark IV

Nope. Remove wheel, move the caliper and go to it!

Well damn, I just checked Wilwood for 12.19 x 1.25 curved vane rotors and mine are all a good two or three hundred a piece. Redvettx2, after hearing Mark IV I would just put two new rotors on the back and not even think about it. It's an easy job and there are a million youtube vids out there on changing out rotors (that aren't 6 pin hubs that is).

[eschaider]

While I respect your opinion Mark IV (apologies, I forgot your first name), as you can see from the screenshot(s) of the SPF Authorized Service Bulletin below, SPF represents the rear rotors on cars 700 to 2636 to be '89 to 92 T-Bird rotors.

Page Header;



Brake Rotor Detailed Information;




SPF Warning / Disclaimer

For reasons I can not understand, the website will say it has uploaded the disclaimer image, but in actual fact, does not, so I have attached it as a jpg file to the end of this post.

While Timemachines may, and I suspect does, do exactly as Mark IV has described it is not consistent with long standing published SPF documentation. That said, the components Mark IV is suggesting I believe, are superior to the OEM FORD rotor approach.

I suspect both components work. If you are doing the service you should explore both alternatives and select the one you feel best meets your objectives.

[patrickt]

Well that's interesting. And they actually call for machining of the rotors.

[Mark IV]

That service bulletin is over 20 years old. Again, machining is possible but not the best choice. The cost of new rotors is not much more than the cost of having them replaced.

[eschaider]

You are right, Mark IV; that is why I described it as, 'long standing published SPF documentation." While I suspect SPF may have published newer documentation since 2002, I am also certain they did not retrofit any brake systems on previously sold cars, which means that their, notwithstanding dated, service bulletin must be correctly identifying the brakes used on those cars built in years past.

I am sure your suggestions as to the Wilwood calipers produces a suitable and safe service alternative; it is just something that postdates the service bulletin, which itself postdates the car in question.

After your Wilwood suggestion for the rotors, I spent some time on the Wilwood site last evening looking for those rotors. The Wilwood rotor listing is impressively long. I gave up before finishing the search. For the benefit of those of us who own SPF cars, could you identify the Wilwood rotor you were speaking of as a replacement rotor?

[patrickt]

Ahhh, wouldn't it be nice if there was a simple straightforward source for a service manual that was complete with part numbers, repair procedures, and made note of the differences in car numbers and that was free to the SPF owner.
See: Just bought a Superformance

[Mark IV]

Originally Posted by eschaider

You are right, Mark IV; that is why I described it as, 'long standing published SPF documentation." While I suspect SPF may have published newer documentation since 2002, I am also certain they did not retrofit any brake systems on previously sold cars, which means that their, notwithstanding dated, service bulletin must be correctly identifying the brakes used on those cars built in years past.

I am sure your suggestions as to the Wilwood calipers produces a suitable and safe service alternative; it is just something that postdates the service bulletin, which itself postdates the car in question.

After your Wilwood suggestion for the rotors, I spent some time on the Wilwood site last evening looking for those rotors. The Wilwood rotor listing is impressively long. I gave up before finishing the search. For the benefit of those of us who own SPF cars, could you identify the Wilwood rotor you were speaking of as a replacement rotor?

https://www.summitracing.com/parts/wil-160-5839

I believe this is the rotor, I am not home and do not have my parts list with me so this from memory so do not order these until I can confirm. Yes, it is more than I said; the prices have risen since I last purchased them. Still a better repair than machining the rotor.

Yes, a proper parts manual would be very nice. The factory would provide one if the distributor would request it and pay for it.

Most dealers have gathered a parts list based upon experience gained over the years and will freely help any owners who inquire. We for example, provide parts that are proprietary to SPF and also non-proprietary parts that we can sell at the common price point. When the part is a common item that we cannot provide at competitive prices, we supply the common part number so the owner can procure the part(s) locally at a good price and without additional shipping costs. Honestly, we would make $2.00 on something like a radiator cap and then need to add $5-8.00 shipping when you can get it at the corner NAPA store. We don't need the $2.00 that badly.

[eschaider]

Originally Posted by Mark IV

https://www.summitracing.com/parts/wil-160-5839

I believe this is the rotor, I am not home and do not have my parts list with me so this from memory so do not order these until I can confirm. Yes, it is more than I said; the prices have risen since I last purchased them. Still a better repair than machining the rotor. ...

Thanks Mark IV.

The rotor in the summit listing is one of Wilwood's two-piece designs with a diameter of 10.75 inches and a thickness of 0.810". The original OEM rotors that SPF provided on the car were 12-inch diameter in the front, with a machine-to-maximum disc thickness of 0.980" and a minimum thickness of 0.865". The Wilwood rotor at Summit does not match the SPF rotor size or thickness specifications for a front rotor. Additionally, because the rotor is a two-piece design, the correct Wilwood hat part number will be required so the rotor is properly positioned in the caliper. When you confirm the rotor suitability, could you also include the hat part number required to properly fit the rotor to an SPF front spindle?

Thanks again for the alternative replacement rotor choice.

[redvettx2]

Mine is an early SPF before Wilwood brakes. Sounds like the rear drums are just 89' to 92' Ford rear Thunderbird drums. Most likely just replace both.

[patrickt]

Originally Posted by redvettx2

Mine is an early SPF before Wilwood brakes. Sounds like the rear drums are just 89' to 92' Ford rear Thunderbird drums. Most likely just replace both.

Drum brakes? Or was that just a typo.

[eschaider]

Originally Posted by redvettx2

Mine is an early SPF before Wilwood brakes. Sounds like the rear drums are just 89' to 92' Ford rear Thunderbird drums. Most likely just replace both.

My SPF service bulletin shows cars 1-699 using '89 - '92 10" Thunderbird rotors in the back. The caliper listed as being used is the OEM T-Bird caliper for the same year. There is no mention of drum brakes ever being used anywhere.

[Mark IV]

Originally Posted by redvettx2

Mine is an early SPF before Wilwood brakes. Sounds like the rear drums are just 89' to 92' Ford rear Thunderbird drums. Most likely just replace both.

The "T-Bird" rear brakes are the "Super coupe" discs, not drums.

[eschaider]

Any updates on the Wilwood part numbers for the Front Rotor and corresponding Hat, Mark IV?