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Author Topic:   chevy rotors
Racer8c
Dirt Full Roller

Total posts: 52
posted February 03, 2003 08:14 PM
What chevy car has a 11" rotor with a 5" lug pattern that will fit a 78 caprice without having to change the spindle assembly?

ars
Dirt Full Roller

Total posts: 34
posted February 03, 2003 08:35 PM
78-79 Buick.......78-79 Oldsmobile....... 78-79 Pontiac....... 78 Buick Riviera. Both the 11 and 12 inch rotors were used on these models and have the 5x5 bolt pattern. The spindle is #774.

c21
Dirt Freak

Total posts: 346
posted February 04, 2003 10:22 AM
quote:
Originally posted by ars:
78-79 Buick.......78-79 Oldsmobile....... 78-79 Pontiac....... 78 Buick Riviera. Both the 11 and 12 inch rotors were used on these models and have the 5x5 bolt pattern. The spindle is #774.

ARS, How could one spindle hold a caliper in the proper location for both a 11" and 12" rotor? (one would think the caliper for a 12" rotor would need to be 1/2" farther from the pin)

I have never seen this 11" 5 on 5 rotor (though I would like to), I have always had to redrill 11" rotors for 5 on 5 (I hear some folks turn down 12" rotors to 11" to get that 5 on 5 pattern) ..... Maybe I've been wasting my time?

c21

Racer8c
Dirt Full Roller

Total posts: 52
posted February 04, 2003 03:56 PM
I tried a 12" rotor on my spindle and they wouldn't clear the caliper mount, I found 11" rotors with 5 on 5 from speedway motors for $60/piece, but I can get all the stuff from one on my sponsors to convert to the 12" with the spindles to match for free, but I was hoping to find 11" rotors on one of the cars he has to save alot of headaches.

c21
Dirt Freak

Total posts: 346
posted February 04, 2003 04:40 PM
quote:
Originally posted by Racer8c:
I tried a 12" rotor on my spindle and they wouldn't clear the caliper mount, I found 11" rotors with 5 on 5 from speedway motors for $60/piece, but I can get all the stuff from one on my sponsors to convert to the 12" with the spindles to match for free, but I was hoping to find 11" rotors on one of the cars he has to save alot of headaches.

If I'm not mistaken, the speedway 5 on 5 11" rotors are metric rotors (redrilled to 5 on 5) and are intended for that application only.

c21

ars
Dirt Full Roller

Total posts: 34
posted February 04, 2003 04:49 PM
c21. The info I posted came from " Street Stock Chassis Technology " book by Steve Smith, sorry for the confusion if data is incorrect. ARS

c21
Dirt Freak

Total posts: 346
posted February 04, 2003 05:01 PM
no need to apologise (we still haven't established that you are wrong, anyway).

I'll have to blow the dust off of my copy and see what 'ol Steve S. has to say about this.

However, I think that it would only be fair if his books had the following warning accross the cover:

"Warning, the information contained within is 70 to 90 percent recycled and only 85 to 95 percent accurate"


c21

widebody
Dirt Maniac

Total posts: 197
posted February 04, 2003 06:29 PM
5x5 = 12"
5x4.75= 11"
unless LT1 camaro rotors 5x4.75 12"

I think the speedway rotors are redrilled or it may be a new casting with the different bolt circle. but not a junkyard part..

The 11" rotors will fit on the 12" spindles just does not make full pad contact with rotor. The 12" rotors can be turned down to fit on the 11" rotor spindles.
Dont get nervous it can be done.!!
I see you mentioned 1978. GM used a different size outer wheel bearing. and you may have trouble matching up parts. I always look for 80 and newer caprices or ==.

Racer8c
Dirt Full Roller

Total posts: 52
posted February 05, 2003 06:35 PM
Thanks for the info guys, I'm just gonna get the 12" and get one of the guys in the tool and die dept. at work to turn them down to 11" for me.

o5racer
Dirt Maniac

Total posts: 115
posted February 08, 2003 09:38 PM
The rotors that everybody sells that have the 5 0n 5 pattern are ordered as blanks and drilled to 5 on 5.

tr14
Dirt Newbie

Total posts: 4
posted February 09, 2003 10:26 AM
78 and newer GM big cars can have either 11 or 12" ,an easy way to tell the difference is by the stud size, 11"has 1/2" studs 12" has 9/16" studs. Salvage yards are full of these cars.

o5racer
Dirt Maniac

Total posts: 115
posted February 09, 2003 12:12 PM
I think you mean 7/16 and 1/2 inch.

racer038
Dirt Roller

Total posts: 16
posted February 12, 2003 05:59 PM
In general, the '77 - mid 80's Impala, Delta 88, LeSabre, and Parisiennes (non station wagons) should have 11" rotors, 7/16" studs and the 5 3/4 pattern. The full size station wagons, Electra 225, 98 Regency and Cadillac de Villes should have the 12" rotors, 1/2" studs and 5X5 pattern. Be careful: inside vs. outside wheel bearings change during the years and can mess you up.

Racer8c
Dirt Full Roller

Total posts: 52
posted February 14, 2003 06:45 PM
Got my rotors, and had a guy in the machine shop at work cut them down, he did a really good job, I haven't been able to put them on yet to see if the bearings are the same yet(raining several days) More than likely I'll have to get over size bearings though.

Racer8c
Dirt Full Roller

Total posts: 52
posted February 18, 2003 05:02 PM
Just so you guys know and don't try the same thing and waste a set of rotors, my 12", converted to 11" rotors are useless now, I couldn't find bearings to fit it so that it would fit my spindles that originally held my 11" rotors. I have to go now and get the whole spindle assembly with the 12" rotors and calipers to get my 5 on 5 pattern.

widebody
Dirt Maniac

Total posts: 197
posted February 19, 2003 05:02 PM
Dont be so hasty.. What year are your spindles? What year rotors do you have?
Are the rotors 1" thick or 1.25" thick?

1978 had real small outer bearings on the full sizes. and 78 and older 12" rotors are 1.25 in thick.

get your self a set of newer spindles from a 11" disk car..

DONT STRESS you'll get ER figured out in time!!!

Racer8c
Dirt Full Roller

Total posts: 52
posted February 19, 2003 07:16 PM
I have to replace the spindles anyway, so I'm just gonna get the spindles that hold the 12" rotors, because the 11" rotors and spindles don't have the 5 on 5 pattern, plus if I go ahead and switch to the 12" spindles and rotors, I won't have to have them ground down to 11" everytime I ***** one up to make them fit.....but thanks for the info.

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