Dumb ?... Brakes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

CHEVYE · 06-09-2005, 01:12 PM

i know this is gonna be a dumb ? but i'm not too informed on brakes

. i just need to know how to tell which rotors i have for drop spindles? these year trucks seem to have a few different sizes. i assume you just measure the thickness but i'm not home now and wanted to make sure before i order them, thanks, eric.

bigblock73 · 06-09-2005, 01:25 PM

measure the width (thickness) of the rotor (the braking surface actually). You will have 1" or 1 1/4".

Easy enough?

I am pretty sure all trucks with the HD leaf packs out back got the thick rotors, but not positive. I am also not sure what criteria as far as options determines the rotor thickness. The only sure way is to measure IMO.

CHEVYE · 06-09-2005, 01:43 PM

preeeeeciate it sir.

Eyegore · 06-09-2005, 02:10 PM

Hey Jeff, doesn't the engine size also determine the width? For example those with the six cylinder and 305's had the 1" and the 350's on up had the 1-1/4". I noticed that my 86 w/ the 305 had the narroer while my son's 78 w/ the 350 had the wider. Does it work that way also taking into account engine swaps?

CHEVYE · 06-09-2005, 02:24 PM

hmmmmmm..... mine was orig. with a 305, i hope i don't have the small pnes. i need them to be large.

Slonaker · 06-09-2005, 02:42 PM

Quote:

Originally Posted by bigblock73

measure the width (thickness) of the rotor (the braking surface actually). You will have 1" or 1 1/4".

Easy enough?

I am pretty sure all trucks with the HD leaf packs out back got the thick rotors, but not positive. I am also not sure what criteria as far as options determines the rotor thickness. The only sure way is to measure IMO.

I have 1" rotors and heavy duty rear springs...

Slonaker

bigblock73 · 06-09-2005, 02:44 PM

Like I said guys, I wasn't exactly sure what dictated the thicker rotors.

I did say MEASURE though.

86 GMG · 06-09-2005, 05:11 PM

imo i would say the older trucks hade 1 1/4 and newer had 1 inch this being changed when the trucks were lightened up a bit i believe this change took place in (81 ???)

MylilBowTie · 06-09-2005, 11:49 PM

My 84 Silverado (had factory 305) has hd rotors and 52in leafsprings 3 + overload with wider drums in the rear I forget the size on the drums.

Turbo85GMC · 06-10-2005, 09:25 AM

Just a hypothetical here......

Say I'm going to order drop spindles so I measure my current rotors and they are 1". If I were going to replace my rotors and calipers *anyway*, could I just order 1.25" dropped spindles and buy new matching brake rotors and calipers???

CHEVYE · 06-10-2005, 11:42 AM

Quote:

Originally Posted by Turbo85GMC

Just a hypothetical here......

Say I'm going to order drop spindles so I measure my current rotors and they are 1". If I were going to replace my rotors and calipers *anyway*, could I just order 1.25" dropped spindles and buy new matching brake rotors and calipers???

as long as the spindles are set up for 1.25" you should be able to change rotors/calipers. the spindles are the foundation and all brake sizes should stem from that.

MylilBowTie · 06-10-2005, 03:51 PM

Don't forget about wheel bearings and seals, they more than likely need replaced and are different sizes stock vs HD rotors.

06-09-2005, 01:12 PM	#1
CHEVYE my gas saver Join Date: Sep 2003 Location: Clarksville, TN Posts: 2,046	Dumb ?... Brakes i know this is gonna be a dumb ? but i'm not too informed on brakes . i just need to know how to tell which rotors i have for drop spindles? these year trucks seem to have a few different sizes. i assume you just measure the thickness but i'm not home now and wanted to make sure before i order them, thanks, eric. __________________ 85' SWB, 4.3/TH350, getting ready for paint 84`SWB, 462ci./TH400, cowl hood, 15" billet spec., flows, blazer buckets/console, flat black 71`SWB, project ebay feedback

06-09-2005, 01:25 PM	#2
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,826	measure the width (thickness) of the rotor (the braking surface actually). You will have 1" or 1 1/4". Easy enough? I am pretty sure all trucks with the HD leaf packs out back got the thick rotors, but not positive. I am also not sure what criteria as far as options determines the rotor thickness. The only sure way is to measure IMO. __________________ Jeff 73-87.com 73-87.com Facebook page 73-87 cab corner 6x9 speaker brackets for sale 67-72 cab corner speaker brackets for sale 47-54 cab corner speaker brackets for sale Last edited by bigblock73; 06-09-2005 at 01:28 PM.

06-09-2005, 01:43 PM	#3
CHEVYE my gas saver Join Date: Sep 2003 Location: Clarksville, TN Posts: 2,046	preeeeeciate it sir. __________________ 85' SWB, 4.3/TH350, getting ready for paint 84`SWB, 462ci./TH400, cowl hood, 15" billet spec., flows, blazer buckets/console, flat black 71`SWB, project ebay feedback

06-09-2005, 02:10 PM	#4
Eyegore What Hump? Join Date: Apr 2003 Location: New River AZ Posts: 2,009	Hey Jeff, doesn't the engine size also determine the width? For example those with the six cylinder and 305's had the 1" and the 350's on up had the 1-1/4". I noticed that my 86 w/ the 305 had the narroer while my son's 78 w/ the 350 had the wider. Does it work that way also taking into account engine swaps? __________________ Lil red 86 c-10 99 Sub 78 Camper Special w/ 454

06-09-2005, 02:24 PM	#5
CHEVYE my gas saver Join Date: Sep 2003 Location: Clarksville, TN Posts: 2,046	hmmmmmm..... mine was orig. with a 305, i hope i don't have the small pnes. i need them to be large. __________________ 85' SWB, 4.3/TH350, getting ready for paint 84`SWB, 462ci./TH400, cowl hood, 15" billet spec., flows, blazer buckets/console, flat black 71`SWB, project ebay feedback

06-09-2005, 02:44 PM	#7
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,826	Like I said guys, I wasn't exactly sure what dictated the thicker rotors. I did say MEASURE though. __________________ Jeff 73-87.com 73-87.com Facebook page 73-87 cab corner 6x9 speaker brackets for sale 67-72 cab corner speaker brackets for sale 47-54 cab corner speaker brackets for sale

06-09-2005, 05:11 PM	#8
86 GMG Registered User Join Date: Apr 2005 Location: Tulsa Oklahoma Posts: 943	imo i would say the older trucks hade 1 1/4 and newer had 1 inch this being changed when the trucks were lightened up a bit i believe this change took place in (81 ???) __________________ square body trucks an addiction or an investment either way they consume all my extra time and money

06-09-2005, 11:49 PM	#9
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	My 84 Silverado (had factory 305) has hd rotors and 52in leafsprings 3 + overload with wider drums in the rear I forget the size on the drums. __________________ 1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI

06-10-2005, 09:25 AM	#10
Turbo85GMC Registered User Join Date: Apr 2005 Location: Medford, MA Posts: 307	Hypothetically Speaking Just a hypothetical here...... Say I'm going to order drop spindles so I measure my current rotors and they are 1". If I were going to replace my rotors and calipers anyway, could I just order 1.25" dropped spindles and buy new matching brake rotors and calipers??? __________________ '85 GMC 1500 "Friends don't let friends drive stock!"

06-10-2005, 03:51 PM	#12
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	Don't forget about wheel bearings and seals, they more than likely need replaced and are different sizes stock vs HD rotors. __________________ 1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI



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