you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Now we all know that the 73-87 front crossmember and suspension components can be swapped into the 60-72 trucks. The 73-80 Chevrolet C10 pickups used a 1.28 rotor. Then in 81-86 GM switched to a 1" rotor. I did a bit more digging and found that the calipers are different for the 1" rotor but use a common bolt pattern with 73-80 so, it looks as if the 91 Camaro rotor will work on the 73-86 spindles if the 81-86 calipers are used as well. Also the flexible brake line will need to be changed if you have the 73-80 caliper as one of the calipers uses American standard thread and the other uses a metric thread. The parts house could not tell me which one used what thread but that they were different. I will figure that out when I purchase the parts. I have not done this yet but it does look like it will work. fones1966 a member here PMed me telling me about this possibility and I want to thank him for that. I just thought I would post this information in case there were others that could use it. Olympic Brake here in Washington is who provided this information. One note I want to point out is the specs that I have all show the same bearings on all three rotors. I was told by fones1966 that the 73-80 1.28 rotor used a A-5 inner bearing so that bearing would have to be replaced when switching to the Camaro rotor but, what I found was the 73-80 heavy duty 1.28 rotor used the A-5 inner bearing and the 81-87 light duty rotor used the A-6 as shown in the specs I have provided. I hope this information is helpful. Here are the specs on both the truck and Camaro rotors:

73-80 Truck rotor specs are:

Height 4.88
Diameter 11.85
Min. Thickness 1.220
Hub 3.06
Outer bearing A-3
Inner bearing A-5
Seal Part # 8871
Bolt Circle 5X5

81-86 Truck rotor specs are:

Height 4.63
Diameter 11.86
Min. Thickness .96
Hub 3.20
Outer bearing A-3
Inner bearing A-6
Seal Part # 8871
Bolt Circle 5X5

91 Camaro 1LE Performance Package rotor specs are:

Height 4.65
Diameter 11.85
Min. Thickness .97
Hub 2.78
Outer bearing A-3
Inner bearing A-6
Seal Part # 8871
Bolt Circle 5X4.75

Re: Do you want to change you 5X5 bolt patern on 73-87 front disc to 5X4.75
 

The Camaro rotor will work on the '81-up 1" spindle. It will not work AFAIK on the 1.25" early spindle...

Re: Do you want to change you 5X5 bolt patern on 73-87 front disc to 5X4.75
 

Well after much research and comparisons this is what I have come up with. I would like to thank gringoloco he helped me out here. The 73-87 2-1/2 drop spindle from CPP uses the A-5 inner bearing that has a 1-3/8" bore. This spindle uses the 1-1/4 rotor with the 5X5 bolt circle. This is the same size spindle as the OEM as well. Belltech has a 3" drop spindle that uses the A-6 inner bearing that has a 1-1/4" bore. This spindle uses a 1" rotor and there for can either be used with the light duty truck 1" 5X5 bolt circle rotor or the Camaro 1" 5X4.75 bolt circle rotor. There it is. This is the only way that I found to switch from the 5X5 bolt circle to the 5X4.75 bolt circle using the OEM rotors. Hope this helps

Re: Do you want to change you 5X5 bolt patern on 73-87 front disc to 5X4.75
 

good to know

Re: Do you want to change you 5X5 bolt patern on 73-87 front disc to 5X4.75
 

why would you want smaller brakes and smaller bolt pattern?
just curious.....

Re: Do you want to change you 5X5 bolt patern on 73-87 front disc to 5X4.75
 

There is no advantage with the smaller bolt circle, there is an advantage with the Camaro brakes. Even though they are a 1" thick rotor, they can be had in a much larger diameter as well as bigger calipers.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

ahhh, I see :thumbs:

Re: Do you want to change you 5X5 bolt patern on 73-87 front disc to 5X4.75
 

If you notice in the first post the Camaro rotor is almost identical as both the 1" & 1.25 truck rotors. The advantage is the 5X4.75 bolt circle in my case. I have a new set of 18X8X4.5 with the 5X4.75 bolt circle Billet Specialties wheels that I want to use on the front of my truck and because you like pictures Joe....:lol:

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

good info,i ran into the same problem, bought some nice cheap 20s and adapters but they wouldnt tuck, so i took my rotors to a machine shop and they knocked the studs out and redrilled the rotors to 5x 4.75 and put my stock studs back in for $100 for the front, and if i ever wanted or needed to go back to 5x5 all i gotta do is knock the studs out and put them back in the factory holes, i took my axles and drums and had them done too for $100

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

I researched this route(in my case it would have been 25.00 per rotor plus studes) but was afraid the redrilling could compromise the integrity of the rotor as part of the webbing on the back of the rotor hub has to be removed in order to redrill. Not to mention the hassle of replacement parts. This way all replacement parts are OEM and available at your local parts store.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

The rotors on my 74 were re-drilled to car pattern & the snout of the hub was turned down to car pattern as well (they were stock Raybestos GM 1/2 ton 1.25" 5x5 rotors). They've seen daily use since '02 w/no issues (been turned one time).

The use of 1LE rotors on LT duty truck spindles would work for a limited use application. But one of the first upgrades made to F-bodies is bigger/better brakes (rotors) that don't warp as easily as the stockers would/could.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Can you explain on the upgrade? I had a 87' SWB and the warping was an issue. Maybe I would be better off redrilling the 1.25 5X5 rotors?

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

The thicker surface area of the 5x5/1.25" thick style rotor is less prone to warping vs. the thinner 5x5/1.00" Lt.Duty rotors. The warping is usually evident in heavier vehicles or those that see harder than normal use (think performance vs. basic passenger transportation).

It also has a lot to do w/factory rotors vs. an aftermarket supplier as not all parts are created equal.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Most F-body guys upgrade to the 1LE brakes. There are kits out there to upgrade to a '98-'02 F-body front brake(12x1.25 -basically the same as your truck brakes) or C5/6 brakes which are 13x1.25. There are upgrades from there to Z06 or Z51 brakes but the parts get spendy...

I've been researching this a little. It looks like the aftermarket C5 upgrade brackets might work on the light duty spindles. That is, if the dust shield/backing plates interchange between big car/light truck, then a bracket may already exist to adapt the 'Vette stuff.

More to come when I get some time...

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Ahhhh . . .... Not a bad idea. Get ride of the problem rotor & keep the spindles w/the appropriate bearing dimensions.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Keep us posted on this.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

So ALL '73-'80 half ton 2wd trucks have the 1.25" rotor?

Thanks!!

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Yes. '71-'80 actually. Around '81 was the start of the light duty brakes.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

And you should be aware that not all '81 up 1/2 tons have the light duty brakes. My 87 1/2 ton has the bigger brakes because it's a diesel (and thus very nose heavy).

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

I was just wondering because the '73-'80 trucks are much more common in my area and I'd rather have the heavier-duty rotor anyway.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

OK, how do I get the 4 3/4" pattern for my rear disc brakes and camaro calipers with Glock's brackets? I haven't been having a lot of luck with this one.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Re-drill rotors/axles is a no brainer. Maybe cross-reference the F-body 1LE rear rotors & see if they'll swap.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Yeah that's what I was finding I was gonna have to do.
The rear f-body hats aren't tall enough. I was hoping someone might have tried some different front options. Maybe s-10 or van or something. I'll keep looking and measuring.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Hhmm.... The S-10 would be my first choice. I might have an S10 rear rotor in my possesion (I had a rear disc set-up for my G-body/pro-tour ride). What measurement would you need?

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

If I remember correctly, :rolleyes: The measurement is from the wheel contact surface to the back of the disc, basically furthest outside point to furthest inside point.
'94-'96 Impala - 2.335" (the brackets are specifically made to work with these but they have the 5x5 bolt pattern)
'89-'92 Camaro rear- 1.97"
'93-'97 Camaro rear- 1.81"
mid '90s S10 I think front - 2.87"
The calipers are from a '97 Camaro because they have the e-brake built in and, of course, work with the brackets.
I can probably use spacers to make some of these work, I'm just not sure how much spacing I want to do and how much is safe.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Ahhh.... The numbers may not mean anything then (because of the different calipers). The set-up I have is OE S10 (11" rotors IIRC) w/OE rear emergency brake.

I have everything minus one rotor that my buddy mis-placed some where along the line. I'll try & grab a rotor & put it inside a wheel & measure from the wheel 'pad' to the inside rotor surface (right?).

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

I just put the rotor hat down on the counter at the parts store and put a straight edge across the top. That is how I got the measurements and they are the same as stated in dimension info.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Will do.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

If you want to convert to the car bolt pattern with factory parts, check with a wrecking yard that uses the Hollander Interchange books. I found that a 71-72 (if I remember the year correctly) G-10 van had the same upper and lower control arms as a C-10 truck, but used the car 4.75" bs rotors. Just score the spindles and for a bolt on conversion. I used this setup years ago to convert a 73 C-10 that I pro-streeted. I had 15X3.5" weld drag lites and they didn't make them in 5X5 bs.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Welcome to the forum Grip we appreciate your input. I am a bit confused as I have always known all GM 1/2 ton trucks, vans, Burbs etc to have a 5x5 pattern.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

not to confuse things too much....
i want to do the opposite camaro clip with 5 on 5 bolt pattern...[56 sub]
so all i need is 81+ 1" rotors using the camaro spindle? caliper?
or do i still need to use the truck caliper brakes?
can i put a truck spindle on the camaro a-arms w/ truck bj's?

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Were there's a will there's a way...Try A&A mfg or UB machine. They both make weld in ball joint bushings that take common Moog ball joints. Just figure out the taper of your ball joint holes in the spindle and adapt your a-arms using the correct weld in ring.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

N2TRUX, Thanks for the welcome. I have been trolling for quite a while but finally decided to sign up. I grew up in a wrecking yard and it was 1987 when I last did the spindle swap. I called my dad who still runs the yard. He is going to look up the interchange # for me. I'll post it as soon as I hear back from him.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

More info...I looked up the rotor for a 71 G-10 and found this on Napa's website:

It list a BUNCH of cars that are 4.75 bs as interchange

Rotor & Hub Assy - Front - Premium

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Front

Part: NB 4885542
Product Line: NAPA Brakes Rotors & Drums


List Price
Your Cost
Unit
:
:
:
93.16
62.80
Each

Qty

Features & Benefits
NAPA Premium Rotors Are Designed To Improve Stopping Distances, Minimize Brake Fade & Extend Pad & Rotor Life.; The Non-Directional Finish On NAPA Premium Rotors Reduces Noise & Braking Roughness.; Vane Configuration Reduces Temperatures & Improves Performance.

NAPA Brakes - Complete Line-Up

Attributes
# of Bolts : 5
Bolt Circle Diameter : 4.75"
Brake Rotor Diameter : 11.005"
Brake Rotor Discard Thickness : .965"
Brake Rotor Thickness New : 1.035"
Brake Rotor Type : Disc Brake Rotor & Hub
Height : 4.639"
Includes ABS Inner Sensor Ring : No
Includes Inner Bearing Cup : Yes
Includes Outer Bearing Cup : Yes
Maximum Lateral Runout : .004"
Mounting Type : Type J - 1 Piece Or Integral Hub & Rotor Assembly. Rotor & Hub Are Cast As A Single Unit. Wheel Studs Are Pressed Into The Rotor. See Diagram For More Information.
Vented / Solid : Vented

Warranty
12 Months or 12,000 Miles Whichever Occurs First

Warranty PDF

Material Safety Data Sheet (MSDS)
There is no MSDS for this item
Application Information: 1971 Chevrolet Truck G10/1500 1/2 Ton - Van
Per Car Qty: 2


Buyers Guide
Make Model Engine Year(s)
Buick Apollo 1975 - 1975
Buick Century 1973 - 1977
Buick Estate Wagon 1977 - 1978
Buick Lesabre 4.9 L 301 CID V8 1977 - 1978
Buick Lesabre 5.0 L 305 CID V8 1978 - 1978
Buick Lesabre 5.7 L 350 CID V8 1977 - 1978
Buick Lesabre 6.6 L 403 CID V8 1977 - 1978
Buick Regal 1973 - 1977
Buick Skylark 1975 - 1978
Cadillac Seville 1976 - 1976
Chevrolet Camaro 1970 - 1978
Chevrolet Caprice 1977 - 1978
Chevrolet Chevelle 1973 - 1973
Chevrolet Impala 1977 - 1978
Chevrolet Malibu 1973 - 1977
Chevrolet Monte Carlo 1973 - 1977
Chevrolet Nova 1975 - 1978
Chevrolet Truck El Camino 1973 - 1977
Chevrolet Truck G10/1500 1/2 Ton - Van 1971 - 1974
GMC Truck G1500 1/2 Ton - Van 1971 - 1974
GMC Truck Sprint 1973 - 1977
Oldsmobile Custom Cruiser 1977 - 1978
Oldsmobile Cutlass 1973 - 1977
Oldsmobile Delta 88 1977 - 1978
Oldsmobile Omega 1974 - 1978
Oldsmobile Vista Cruiser 1973 - 1975
Pontiac Bonneville 1977 - 1978
Pontiac Catalina 1977 - 1978
Pontiac Firebird 1970 - 1978
Pontiac Grand Am 1973 - 1975
Pontiac Grand LeMans 1975 - 1977
Pontiac Grand Prix 1973 - 1977
Pontiac GTO 1973 - 1973
Pontiac LeMans 1973 - 1977
Pontiac Parisienne 1977 - 1978
Pontiac Phoenix 1977 - 1978
Pontiac Ventura 1975 - 1977

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Well, you are correct on this... In addition to 71-72 there is also 73-74 G-10 vans. These (71-74 G-10) use the 70-78 camaro rotor & caliper. So, there are numerous outlets for big brake kits. Bear, SSBC, etc...
There is a difference between 71-72 & 73-74 G-10 Spindles, the outer tie rod mount is different. It's thicker where the taper of the outer tie rod goes thru the spindle.
As far as the outer tie rod ends used:
71-72 G-10 is same as 71-72 C-10
73-74 G-10 is same as 73-74 C-10
If I remember correctly, the 73-74 tie rod hole is thicker top to bottom.
In 75 G-10 went to 5 on 5 bolt pattern.

I have a set of each 1) 71-72 G-10 van spindles complete & 1) 73-74 G-10 van spindles complete.
My plan was to build a race truck style build and use cross drilled rotors that are commonly available for 70-78 camaro rotors as well as aftermarket race caliper (wilwood, strange, etc...) I actually had them mounted on a rolling frame for awhile with 15x7 ralley's for about a year before I changed my vision for the project.


P.S. yeah, I've worked in auto parts for 22 yrs, 5 yrs of that at NAPA, so, had lots of time to research stuff like this...
If you wanna talk using stock parts to come up with 6 on 5-1/5" disc brakes PM me, I've researched that as well, If I remember SCOTI helped me on that deal... that was awhile back, If SCOTI doesn't remember helping out, I'll take FULL credit for the research.... Just kidding SCOTI.
Bryan

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

67 swb cst,

What is the "Height" measurement in the specs measuring?
Is that how tall it is from rotor hat to the rear disc surface?
If it is, I'm trying to find something that's much closer to 2.335.

Thanks,
Jim

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Thanks for the info Grip and 67 cst swb. I always hear guys talking about running van rallies on the front because they are narrower than truck rallies. I had never heard that there were specific years that were not 5x5.

And now I know "the rest of the story"...;)

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Yes on the rotors. Use '81-up 1" truck rotors or B-body(Caprice)- same part number. They will still use the car calipers.

On the spindles- not that I'm aware of, but I seriously doubt it...

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Sorry if I caused confusion...
The area that is thicker is where the outer tie rod mounts to the spindle (the tapered hole on the spindle). It is the same on the 73-74 G-10's as the 73-79 C-10. (I will edit this info above)
The 71-72 G-10 tie rod end mount thickness is the same as 71-72 C-10's.
BUT, 71-72 years are different than the 73-later (73-later being the thicker of the two)...
Check back to this thread later, as soon as I can I will get you the measurments.

Re: you want to change your 5X5 bolt pattern on 73-87 disc to 5X4.75
 

Ok, this has also sparked my interest...
What year camaro clip/subframe/rotor are you currently using? I may have a simple fix for you, but I need more info.
If it's easier for you... Call me at work 605-348-3850 M-F (9-6 MT)

I think I know how you can get a bolt on 5 on 5 bolt pattern rotor to go onto a stock camaro spindle (depending on year spindle used).