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  Topic Review (Newest First)
02-08-2020 05:27 PM
Big Dave
Quote:
The reason I ask is there is a lot of suppliers that list front calipers and rotors for A Bodies years 1967 - 1968.
The factory never installed them and the dealer couldn't either because the parts had not been placed into production in that time frame.


Because GM has only one part to fit every application with any new part having to be backward compatible (to prevent having two parts in inventory to fit new and old cars) then you can add more modern parts to older cars that used the same part. In this case it is the steering knuckle that on the Chevelle was the same from 1967-'72.

This one part policy was dictated Nov 1957 to reduce GM's income tax paid to Uncle Sam: as it was the number of items you held in inventory that determined what you owed. Fewer parts less money for Uncle Sam and more money to spend on bonuses for the board of directors.

This policy made GM rich, but also eventually killed it. Because people discovered that their Cadillac was nothing more than a really high priced Chevrolet after 1974. This was because there was no difference in the cars when all of General Motors divisions started using only Chevy engines and transmissions. Cadillac still had it's own North Star dual overhead four valve per cylinder engine, but it was smaller than 350 cubes in size (previous Caddy engines where 472 to 500 cubes big), and the North Star was a high priced option with the SBC 350 the base engine included with your over priced Caprice. That is what killed sales and drove GM into bankruptcy.

You need to find a Hollander for the year you are trying to build to find out what parts interchange. Alan Colvin's book Chevrolet by the Numbers also helps as it is a listing of all of Chevy engine and power train parts used from 1955 through 1970 (spread across four books). The rest comes from experience (and I have been working on cars and racing them since 1963).

Big Dave
02-08-2020 04:55 PM
unda_da_bonet
Quote:
Originally Posted by Big Dave View Post
A-body never used the four piston caliper. It had a single piston as a rare option (Y51 RPO code) starting in 1969 through 1972, they were redesigned in 1972 to use a brake compatible with the lighter Camaro and Nova cars. It was redesigned again in the eighties to go metric with an even smaller single piston metric caliper and used through the remainder of the A, F, and G body cars. In 1967 -'68 the Camaro used the same Corvette rotors and calipers as the Corvette with a special RPO code of JL8 for four wheel discs or J56 for front wheel only disc brakes).



Big Dave

Oh boy am I confused then............


Would the A Bodies have had front disc brakes as a dealer option then if they weren't a Factory fitted option?
The reason I ask is there is a lot of suppliers that list front calipers and rotors for A Bodies years 1967 - 1968.


https://www.elcaminostore.com/el-cam...1967-1968.html
https://www.elcaminostore.com/el-cam...1967-1968.html
https://www.ecklerschevelle.com/chev...1967-1968.html
https://www.ecklerschevelle.com/chev...1967-1968.html
https://www.opgi.com/brake-systems/d...t-ch31112.html
https://www.opgi.com/brake-systems/d...y-kr20106.html
https://www.opgi.com/brake-systems/d...t-ch31112.html

https://www.opgi.com/brake-systems/d...y-kr20106.html


All the links above are for A Body cars 1967-68 which is why I asked the question above.
02-05-2020 07:33 PM
Big Dave A-body never used the four piston caliper. It had a single piston as a rare option (Y51 RPO code) starting in 1969 through 1972, they were redesigned in 1972 to use a brake compatible with the lighter Camaro and Nova cars. It was redesigned again in the eighties to go metric with an even smaller single piston metric caliper and used through the remainder of the A, F, and G body cars. In 1967 -'68 the Camaro used the same Corvette rotors and calipers as the Corvette with a special RPO code of JL8 for four wheel discs or J56 for front wheel only disc brakes).

In 1963 The Corvette got IRS and Disc brakes on all four corners. They licensed Girlings design. The Full size Chevy which shares part with the 'vette, got a set of four piston calipers in 1967 using the rear caliper off of a 1965 'vette (the rear rotor was thinner than the front disc on a 'vette so it was chosen even though the rear rotor on a 'vette has shoes inside the hat that acts as a drum on the rear rotor). The Impala hada unique two piece fron rotor with a special wheel bearing that rode in the one of a kind hub. In 1968 the caliper was changed to accept the thicker front rotor of the 'vette; but retained a unique steering knuckle and front hub that bolted a rotor to it. In 1969 the single piston full floating caliper in a unique size that only fit 196'and 70 cars (can be retro fitted to the 1965-'70 bodies with the correct parts). In 1971 through 1984 GM used a caliper off of a light truck with a five stud rotor that fit on the drum brake spindle so that you can more easily upgrade to discs on the 1971-'76 body years. Can't remember the year disc brakes up front became standard.

There fore you have part number changes by year and model which is why there are so many different castings out there. No they do not interchange as piston diameters differed as well as the distance between the pads (rotor thickness). You will need an assembly manual for each year and model to cross reference part numbers, or look at a book such as Alan Colvin's Chevrolet by the Numbers 1965-'69.

https://www.ecklerscorvette.com/chev...E&gclsrc=aw.ds

My mom's 1968 Caprice 9C1 copo car had front disc brakes and a 360 horse 327 with a TH400 tranny and 12 bolt rear. I owned two J56 optioned 1968 Camaros (one SBC and one a 427 BBC Baldwin Motion phase III RS/SS car that had a motor built by Don Yenko

Big Dave
02-05-2020 04:23 PM
unda_da_bonet You are No help guys...............



I mean no disrespect, but a blind man can see the difference between the cars.
Its "My Bad" if I didn't explain myself better, sorry.



If you had a look at the link it shows calipers with what looks like the same part numbers on the actual replacement calipers as the ones on my car.


What I wanted to know is that correct did they use the same caliper?
Bigdave you always talk about interchangability between models and Makes, thats all.
I can't find any information about part numbers on the A body front disk brakes for the Pontiac cars of that era. That information seems impossible to find.



Thanks.
02-04-2020 01:48 PM
Deadwolf
Quote:
Originally Posted by Big Dave View Post
800 pounds of sheet metal, and the size of the parts (example the Impala B-body uses a 5/8"-18 RH thread on it's tie rod ends to adjusting sleeve and the A-body uses a half inch (which is smaller and won't fit).

GM engineers designed parts for vehicles according to their top speed (with a faster vehicle creating more stress on parts and there by they are made bigger and stronger, and the gross vehicle weight with barges like the full size sharing parts with the light pick up because six AMERICAN adults and golf bags in the trunk is about as much weight as a half ton pick up can handle.

Big Dave
Not to mention a lot of full size owners would tow campers on the weekend with their car. Heck I've seen some use the family Impala to tow the race car to the track. You didn't find many A-body cars expected to work like that.
02-03-2020 07:23 PM
Big Dave 800 pounds of sheet metal, and the size of the parts (example the Impala B-body uses a 5/8"-18 RH thread on it's tie rod ends to adjusting sleeve and the A-body uses a half inch (which is smaller and won't fit).

GM engineers designed parts for vehicles according to their top speed (with a faster vehicle creating more stress on parts and there by they are made bigger and stronger, and the gross vehicle weight with barges like the full size sharing parts with the light pick up because six AMERICAN adults and golf bags in the trunk is about as much weight as a half ton pick up can handle.

Big Dave
02-03-2020 06:36 PM
unda_da_bonet
Are These Any Good ?

Hello all,


Any help would be great, thanks.


I have found these at OPGI


https://www.opgi.com/brake-systems/d...h31112-pr.html


Would they fit my 1967 Impala?


I know they are listed for A Bodies but is there a difference?


Thanks.
01-09-2020 08:52 PM
unda_da_bonet
Interesting Reading

Thanks Big Dave,


A lot of good information there.
I have since found a lot more information on that site re converting the front to C3 disc brakes.


My only problem with that is we don't have to many wrecked C3 corvettes in this part of the world and the freight cost would be the same for new parts as well as second hand parts shipped to Australia.


Ecklers have a good array of new C3 front end stuff to convert my 67.


Not to mention there is always Wilwood.............


Still weighting up my options.


Cheers,
Chris.
01-09-2020 11:27 AM
Big Dave One other option that I would consider if it were my car would be to substitute reproduction Corvette brakes off of a 1968-'82 (C3) brake system. You need to swap the steering knuckles and everything that bolts to it as the spindles differ in size.

People have been doing this swap (and other Corvette parts onto to their Chevys) for years:

https://www.chevytalk.org/fusionbb/s...hp?tid/337227/


It will look stock when done and everything should fit as the factory intended if you get one year for all of the parts.


Big Dave
01-08-2020 11:40 PM
unda_da_bonet
Conclusion

Well I've done some more investigating (anybody would think I have nothing better to do) and found Rockauto has both Impala and Corvette pistons.
They are in fact different.


Impala Piston :2.057"

https://www.rockauto.com/en/moreinfo...21478&jsn=2248


Corvette Piston :1.87"
https://www.rockauto.com/en/moreinfo...=2221&jsn=2221


So in conclusion the Front disk brakes on a 67 and early 68 Impala are a year/model specific option and not as interchangeable as I first thought.


I'm now leaning towards replacing them with Wilwood.


Cheers,
Chris.
01-08-2020 10:14 PM
unda_da_bonet
Update

[QUOTE=unda_da_bonet;227484]

Can I use that kit once I have sleeved my calipers? Apparently Not!

That is I'm believing my 67 Impala calipers to be the same internally? Not If my measurements are correct?


I've taken my original calipers apart and did some measuring of the bore size and the size of the piston and here are the measurements :


Internal bore size is 2 and 1/16th or 52 mm


Piston diameter is 2 inch exactly or a smidgen under 51 mm


Haven't got a reply from the corvette people yet.
I did some digging on the web and found most or general consensus says the C3 Corvette piston size for the front is 1 and 7/8ths


I only hope I'm measuring it correctly and if anyone has a Impala front disc piston lying around and cares to measure it for me to confirm that would be great.

I don't hold much hope of that happening though..............


Should I here back from the Corvette people I'll keep you updated.



Thanks,
Chris.
01-07-2020 05:29 PM
unda_da_bonet Thanks for the advise Big Dave,
Especially about the brake fluid, some thing always over looked me included.
I did go to a Corvette site before posting here and look at previous posts, the general consensus was the o'rings were better
That is after the stainlees steel sleeving had been done.
I'll see if I can post on a Corvette site and get their opinion as well and report back.

Cheers,
Chris
01-06-2020 01:36 AM
Big Dave I would retain the lip seal cups. With stainless steel sleeves you should no longer have corrosion problems. Just remember to change the brake fluid with a full flushing of system every two years or so to get rid of any moisture the brake fluid picks up.

Since the Girling style brakes were used on the Corvette from 1965 through 1982 a Corvette board will have the definitive answer to your question as to the pros and cons of modifying the brakes.

Big Dave
01-05-2020 10:29 PM
unda_da_bonet
Factory Fitted Caliper Help ?


I have factory fitted 4 piston calipers on the 67 and are on the second rebuilt set in 4 years.
I have found out the hard way that having the car sit round doesn't help them either (Rust in bores).


I'm now getting a set stainless sleeved at a cost of $110 Aus a half (X 4 = $440) Yes expensive.........
My question is, can I use o'rings on the pistons or do I have still use the old lip design seals?
Do I need to change the pistons to newer one to use the o'rings?


I found on the Ecklers Corvette site a kit to change 65-82 year caliper to o'rings,


https://www.ecklerscorvette.com/corv...1965-1982.html


can I use that kit once I have sleeved my calipers?

That is I'm believing my 67 Impala calipers to be the same internally?


I know some of you would suggest just changing the whole front brake system over to Wilwood or the likes, but.
I have disk brake front spindles I'd need to change for new (CPP $159 pair) or second hand, wrecking yard (Aus - Nil, USA very few)


The new Wilwood brake kit is 140-12022 Summit Racing $902 USD ($1300 Aus + freight $3-400)
Affordable, yes but not original.


There is nothing wrong with the factory setup when working right, I'm more than happy to keep them.
I just need some advise if anyone can help,


Thanks,
Chris.

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