Rotor Thickness?

Ooooner · 07-11-2007

I just measured the thickness of my front brake rotors after they were turned. One of them is .388 and they other is .370. Harold Collins looked up the minimum thickness for the rotors on GT's and it said the minimum should be .394.
I was just wondering if you think the rotors are too thin now or maybe they should still be OK until the next time then I would have to replace the rotors. By the book, Harold said that if it was under .394, the rotors should be thrown away. These numbers seem to be close enough for at least one more use.

hrcollinsjr · 07-11-2007

Roy,

I forgot to ask you, did someone turn them for you? If so and lack of brakes can be blamed for your demise, keep the receipt. I have an answer to, "Whos yo Daddy?" Roy Bell is! I always wanted to have a little extra income and not have to work for it.

Harold

markandson · 07-11-2007

Got figure that the Opel engineers had a margin of safety built into that minimum number, so I would say go for it. The result of the too thin rotors will be increased fade on hard stops and possible rotor warpage.

hrcollinsjr · 07-11-2007

Seriously, Jeff is probably correct, especially if your driving style doesn't include practicing for autocrosses everytime you get behind the wheel.

Harold

Ooooner · 07-11-2007

Jeff and Harold,
That's about what I thought. I'm not going to be driving on a race track any time soon so I thought it would be OK. Doesn't hurt to ask... Thanks for your inputs!

Paul · 07-11-2007

The other POTIENTIAL problem thin rotors can cause is the caliper piston coming out of the bore when the pad wears down to the backing....

So keeping these issues in mind, no hot and heavy braking or letting the pads wear completely down, you should be okay...

markandson · 07-11-2007

Originally Posted by Paul

The other POTIENTIAL problem thin rotors can cause is the caliper piston coming out of the bore when the pad wears down to the backing....

So keeping these issues in mind, no hot and heavy braking or letting the pads wear completely down, you should be okay...

I think you are talking some serious cheating in order for this to happen

Paul · 07-11-2007

Originally Posted by markandson

I think you are talking some serious cheating

Oh what are you refering to... the HOT and HEAVY?

Lindsay · 07-11-2007

Just checked old rotor that is stamped 10 mm (.394 in) min.

For some reason Bembo paper spec. is different?
Brembo Solid Brake Disc: buybrakes.com
Brembo 25002 Rotors:
Type: Solid Disc
Overall Diameter: 238mm
Minimum Thickness: 8mm (.315 in)
Overall Height: 55.5mm

GTJIM · 07-12-2007

There - that horrible, fearsome word again ......

If you have an accident and cause damage or injury and the insurance companies find out you knowingly used rotors turned undersize .....

Say no-more ....

Start looking for some NEW Opel disc rotors - they are remarkably inexpensive and by far the best way to go with stock brakes.

yellaopelgt · 07-12-2007

I think Parts america has them(Brembo)....I replaced mine a year ago and it was like $70.00 for both. And to have them turned down around my neck of the woods was like $16 or $18 bucks a side. I opted to just replace them and not worry about it for quite some time. But...to each his own I guess. After all, I've got SOOO much money sunk into this car I'm not gonna start getting cheap especially with the brakes!!! BTW new rotors and a set of Green Stuff pads, STOPS ON A DIME!!!!

Joe

yellaopelgt · 07-12-2007

Almost forgot.... its a good time to clean off all the 35+year old grease and re-pack those bearings with some GOOD quality high temp stuff while your in there!!!Replace that old cotter pin too................
HTH Joe

hrcollinsjr · 07-12-2007

Originally Posted by yellaopelgt

Replace that old cotter pin too................
HTH Joe

With another metric cotter pin. If the old one is loose you can bet it is an SAE cotter pin. If they call it a "carter pin" you might not want to ask about a metric one.

Harold

briarrose · 07-12-2007

What kind of greese did you use? I was reading about that in the emergency kit stuff and all we have doesn't look right to me. The can reads kluberlube nbu 18 but it looks like lard or something and is kinda white. Is this the right stuff? Sorry if this isn't right, but was reading the one about emergency kits and was looking at what we have here.

hrcollinsjr · 07-12-2007

Originally Posted by briarrose

What kind of greese did you use? ... it looks like lard or something and is kinda white. Is this the right stuff?

Sounds like you have a can of lithium grease. It's used for a lot of things, hinges and linkages come to mind but NOT wheel bearings.

Harold

soybean · 07-12-2007

Brembo, isn't listed at Parts America anymore, which is where I got mine too.
Beck/Arnley and Raybestos Brake Rotor: PG Plus are listed now. Raybestos has the following listed : New Surface Thickness .43".
Discard Thickness: .396"
Beck/Arnley has no specs listed. Hth, Jarrell

briarrose · 07-12-2007

On the canister it says it's a high temperature high RPM synthetic grease made in Germany. So this isn't the right grease to use? I just want the emergency kit to have all the right things if we ever go on a long drive in it.

Paul · 07-12-2007

You can't go wrong with RedLine CV-2 Synthetic...

Racer Parts Wholesale Home Page

07-11-2007	#1 (permalink)
Ooooner Moderator Join Date: Mar 2002 Location: Concord, North Carolina Posts: 1,118 Real Name: Roy Bell	Unanswered: Rotor Thickness? I just measured the thickness of my front brake rotors after they were turned. One of them is .388 and they other is .370. Harold Collins looked up the minimum thickness for the rotors on GT's and it said the minimum should be .394. I was just wondering if you think the rotors are too thin now or maybe they should still be OK until the next time then I would have to replace the rotors. By the book, Harold said that if it was under .394, the rotors should be thrown away. These numbers seem to be close enough for at least one more use. __________________ Roy Bell 1973 Opel GT 74 Manta Rallye Concord, North Carolina Carolina Opel Club OMC

07-11-2007	#5 (permalink)
Ooooner Moderator Join Date: Mar 2002 Location: Concord, North Carolina Posts: 1,118 Real Name: Roy Bell	Jeff and Harold, That's about what I thought. I'm not going to be driving on a race track any time soon so I thought it would be OK. Doesn't hurt to ask... Thanks for your inputs! __________________ Roy Bell 1973 Opel GT 74 Manta Rallye Concord, North Carolina Carolina Opel Club OMC

07-11-2007	#6 (permalink)
Paul Member 1000 Post Club Join Date: Mar 2002 Location: Ft Smith, Arkansas Posts: 1,481 Provided Answers: 1	The other POTIENTIAL problem thin rotors can cause is the caliper piston coming out of the bore when the pad wears down to the backing.... So keeping these issues in mind, no hot and heavy braking or letting the pads wear completely down, you should be okay... __________________ Paul

07-11-2007	#9 (permalink)
Lindsay Opeler Join Date: Jul 2003 Location: San Diego, CA Posts: 508 Provided Answers: 1	Brembo Rotor Spec Just checked old rotor that is stamped 10 mm (.394 in) min. For some reason Bembo paper spec. is different? Brembo Solid Brake Disc: buybrakes.com Brembo 25002 Rotors: Type: Solid Disc Overall Diameter: 238mm Minimum Thickness: 8mm (.315 in) Overall Height: 55.5mm

07-12-2007	#10 (permalink)
GTJIM Old Opeler Join Date: Jun 2003 Location: New Zealand Posts: 5,686 Provided Answers: 12	Liability ..... There - that horrible, fearsome word again ...... If you have an accident and cause damage or injury and the insurance companies find out you knowingly used rotors turned undersize ..... Say no-more .... Start looking for some NEW Opel disc rotors - they are remarkably inexpensive and by far the best way to go with stock brakes. __________________ GTJim Opel Owner since last Century! Copyright © 2000-2009 J D Henry All Rights Reserved

07-11-2007	#2 (permalink)
hrcollinsjr 2200 Post Club Join Date: Jan 2003 Location: Chapel Hill, TN Posts: 2,267 Real Name: Harold Collins Provided Answers: 14	Roy, I forgot to ask you, did someone turn them for you? If so and lack of brakes can be blamed for your demise, keep the receipt. I have an answer to, "Whos yo Daddy?" Roy Bell is! I always wanted to have a little extra income and not have to work for it. Harold

07-11-2007	#4 (permalink)
hrcollinsjr 2200 Post Club Join Date: Jan 2003 Location: Chapel Hill, TN Posts: 2,267 Real Name: Harold Collins Provided Answers: 14	Seriously, Jeff is probably correct, especially if your driving style doesn't include practicing for autocrosses everytime you get behind the wheel. Harold

07-12-2007	#11 (permalink)
yellaopelgt No....its not a Buick.... Join Date: Feb 2005 Location: IL. Posts: 1,042 Provided Answers: 1	I think Parts america has them(Brembo)....I replaced mine a year ago and it was like $70.00 for both. And to have them turned down around my neck of the woods was like $16 or $18 bucks a side. I opted to just replace them and not worry about it for quite some time. But...to each his own I guess. After all, I've got SOOO much money sunk into this car I'm not gonna start getting cheap especially with the brakes!!! BTW new rotors and a set of Green Stuff pads, STOPS ON A DIME!!!! Joe __________________ What ...we got here...is........failure......................... to communicate.... Some men,you just cant reach...so you get what we had here last week...which is the way he wants it. Well, he gets it...I dont like it, any more than you men...

07-12-2007	#12 (permalink)
yellaopelgt No....its not a Buick.... Join Date: Feb 2005 Location: IL. Posts: 1,042 Provided Answers: 1	Almost forgot.... its a good time to clean off all the 35+year old grease and re-pack those bearings with some GOOD quality high temp stuff while your in there!!!Replace that old cotter pin too................ HTH Joe __________________ What ...we got here...is........failure......................... to communicate.... Some men,you just cant reach...so you get what we had here last week...which is the way he wants it. Well, he gets it...I dont like it, any more than you men...

07-12-2007	#14 (permalink)
briarrose No Access Join Date: Jul 2007 Location: at home Posts: 31	What kind of greese did you use? I was reading about that in the emergency kit stuff and all we have doesn't look right to me. The can reads kluberlube nbu 18 but it looks like lard or something and is kinda white. Is this the right stuff? Sorry if this isn't right, but was reading the one about emergency kits and was looking at what we have here.

07-12-2007	#16 (permalink)
soybean Moderator Join Date: Nov 2002 Location: Reidsville N.C. Posts: 2,160	Brembo, isn't listed at Parts America anymore, which is where I got mine too. Beck/Arnley and Raybestos Brake Rotor: PG Plus are listed now. Raybestos has the following listed : New Surface Thickness .43". Discard Thickness: .396" Beck/Arnley has no specs listed. Hth, Jarrell __________________ You lose your dreams, you lose your mind. (The Rolling Stones) Last edited by soybean; 07-12-2007 at 08:36 AM. Reason: URL link doesn't come up

07-12-2007	#17 (permalink)
briarrose No Access Join Date: Jul 2007 Location: at home Posts: 31	On the canister it says it's a high temperature high RPM synthetic grease made in Germany. So this isn't the right grease to use? I just want the emergency kit to have all the right things if we ever go on a long drive in it.

07-12-2007	#18 (permalink)
Paul Member 1000 Post Club Join Date: Mar 2002 Location: Ft Smith, Arkansas Posts: 1,481 Provided Answers: 1	Wheel Bearing Grease You can't go wrong with RedLine CV-2 Synthetic... Racer Parts Wholesale Home Page __________________ Paul

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