70 LT1 suspension resto dilemma

[Kim B.]

Re: 70 LT1 suspension resto dilemma

Dan: FYI both calipers are 5469588 with no X. Thanks to all you guys for the help!! I do want to get the car judged and heaven knows I'll need the points, but I'm leaning towards doing the car the way the original owner said it was and the way it came to me. Kim

[Joe L.]

Re: 70 LT1 suspension resto dilemma

Dan: FYI both calipers are 5469588 with no X. Thanks to all you guys for the help!! I do want to get the car judged and heaven knows I'll need the points, but I'm leaning towards doing the car the way the original owner said it was and the way it came to me. Kim

Kim-----


I assume you're talking about the casting number of one of the caliper halves on each side, probably the outer caliper half. What is the casting number of the caliper half on the other side of each caliper?

What about the rear calipers? Do you have casting numbers for each of the four caliper halves?

[Michael W.]

Re: 70 LT1 suspension resto dilemma

Another thought- if you were to remove all traces of the 'incorrect' hardware and replace it for judging purposes, the deductions for repo parts may be the same or higher than what's installed now. I'd have a tough time looking at an original 7 leaf spring and giving it a bigger deduct than a modern incorrect repo 9 leaf

[Kim B.]

Re: 70 LT1 suspension resto dilemma

Kim-----


I assume you're talking about the casting number of one of the caliper halves on each side, probably the outer caliper half. What is the casting number of the caliper half on the other side of each caliper?

What about the rear calipers? Do you have casting numbers for each of the four caliper halves?

Joe: On the front - out is 5452273, in is 5469588 on both sides. On the back - out is 5452284, in is 5452281 on both sides. Thanks, Kim

[Mike G.]

Re: 70 LT1 suspension resto dilemma

the books can be changed if you can prove the factory put the parts on there. i have seen it before. i have an 86 pace car with 20k miles. when i was getting it judged i got a deduct for not having a date stamp on the back window even though i knew it was the original top. lucky for me there was another car just like mine getting judged at the same time. the cars were built in the same month and the original owner still owned the car. his original top anso had no date code so i did not get a deduct. of course the top thing is not as big of a deal as suspension parts, it still went against what everyont thought to be true. if you cant prove it you have to take them off to get the points. i also have a 70 lt1 vert i am restoring. mine was an all original car (rough) and i guess i am lucky that all seems normal with mine. mine is a later june car with a CTK block. mine is 12551

[Joe L.]

Re: 70 LT1 suspension resto dilemma

Joe: On the front - out is 5452273, in is 5469588 on both sides. On the back - out is 5452284, in is 5452281 on both sides. Thanks, Kim

Kim-----


The front outers and both of the rear castings are exactly what's correct for a 1970. The front inner is the "oddball", but that's exactly what I would expect. You might want to "double check" the casting numbers on both of the front inners. If my recollection is correct, these castings only have one of the brake line bosses. If so, that would make them side-specific and a different casting number would have to be used on either side. However, I think the numbers might be only one digit different (i.e. 5469588 and 5469589 or 5469587). If the last digits are "8" and "9" that will make it tough to discern. You'll have to look at them VERY closely. However, if I'm correct about these castings having only one brake line boss (which you can also confirm), then the casting numbers have to be different.

As I mentioned previously, I was told that these castings were used on 1969 Camaros with 4 wheel disc brake option. However, there's absolutely no reason that they could not also have been used for Corvette. If I'm correct about the Camaro application, the "JL-8 Camaro guys" would probably pay a "King's Ransom" for them. I wonder if there are any JL-8 Camaro experts around that could confirm what I'd been told about these caliper castings' use on JL-8 Camaros?

[John H.]

Re: 70 LT1 suspension resto dilemma

As I mentioned previously, I was told that these castings were used on 1969 Camaros with 4 wheel disc brake option. However, there's absolutely no reason that they could not also have been used for Corvette. If I'm correct about the Camaro application, the "JL-8 Camaro guys" would probably pay a "King's Ransom" for them. I wonder if there are any JL-8 Camaro experts around that could confirm what I'd been told about these caliper castings' use on JL-8 Camaros?

Joe -

I don't have the caliper half casting number level of detail on the Camaro JL-8 4-wheel disc brake package (only 199 were built out of 350,000 '69 Camaros), but the JL-8 package used the standard single-pin calipers. That's about all I know about it.

[Joe L.]

Re: 70 LT1 suspension resto dilemma

All-----


I went out and did a little more research today on these "oddball" inner front caliper halves today. Now, I'm not so sure about what I've been told about them as being Camaro pieces. For one thing, I cannot see any reason why the deletion of one of the brake line fitting bosses would have been necessary for a Camaro application. For another thing, these definitely look to me like an original (i.e. not converted) dual pin caliper half. With Camaro JL-8 using the single pin caliper as John reports, that would pretty much leave these out for the Camaro application.

Based upon the further research I did today, what I do know is this:

1) These are definitely a second design type caliper; there is NO evidence of piston guides ever having been included in these castings. This means they were not used before E1967;

2) The castings definitely appear like other J-56 calipers in the sense that there was a pin boss as part of the casting and this was machined off in the process of making them "dual pin";

3) There is only one brake line fitting boss on these calipers. This means that there MUST be 2 different castings---one for the left side and one for the right side;

4) There is a very unusual casting mark on these calipers. I believe it's a foundry identification mark. It's a "T" with a partially flattened bottom. However, there's also a "wagon wheel" symbol which indicates that these were a Central Foundry Division cast piece. I don't think these were cast at Danville, IL which is where other 65-72 caliper halves were cast;

6) Based on certain casting configurations, I believe these are malleable or nodular iron castings like all other 65-72 castings but unlike 73-82 castings.

It MIGHT even be that all L1967-72 Corvettes with J-56 brakes used these calipers for the inner fronts. It might also be that only some used them. Anyone out there with a KNOWN ORIGINAL L1967-72 J-56-equipped car that could check the inner front caliper casting numbers and report what they find?

The BIG question for me is WHY these calipers were ever produced. I just don't see any reason that would justify a special casting which would delete one of the brake line fitting bosses. The weight savings would amount to only a few ounces, at most, and the caliper would be no stronger. In fact, it might not be as strong. So, why this was ever done is a BIG MYSTERY to me.

Also note that this caliper half has a tiny stamping on one of the top machines surfaces. This is as Patrick Hulst has previously reported. I looked at a LARGE NUMBER of casting cores about a year ago and didn't find a single one that had this stamping. Today, I saw several with it, including the caliper half pictured. This one appears to be "53".

Some more photos of the caliper in question are seen below and in following posts:

[Joe L.]

Re: 70 LT1 suspension resto dilemma

More photos

[Joe L.]

Re: 70 LT1 suspension resto dilemma

Still more

[Dan P.]

Re: 70 LT1 suspension resto dilemma

Dan----


What are the caliper casting numbers on your car?

Joe & Kim-

The casting numbers of the inner halves of both Right and Left J56 calipers on my '70 ZR1 are 5452270. Obviously, they're identical with opposite bosses drilled to accept the brake lines. Here's a photo of one - can't see the numbers but details configuration.

Note this is how I found the car - the fellow I bought it from learned it was a ZR1 only because he couldn't find J56 brake pads. This was his solution!

[Wayne B.]

Re: 70 LT1 suspension resto dilemma

Wow, I wouldn't be in a hurry to break up that car just yet, it may very well be a piece of history that needs exploring. I've been banging away on my 70 LT-1 for a good while which keeps me reading more and more and, while I don't pretend to be an expert like many here that have studied them more and even worked the line building them, there is one thing I have come away with...I just don't trust GM's record keeping from that era, it was just too sloppy and, with only gut feeling as evidence, think there was a whole lot of "wink and a knod" dealing going on when it came to equiping Vettes back then. There seemed to be a number of dealers, being the salesman they are, that could work around any "rules" to get a car made the way they needed to make a sale (I never under estimate a slick salesman). It would really be a shame to disassemble a piece of history without realizing what it truly is. Who knows, maybe the dealer helped the Vet out and put the power windows in or conned the factory into it. Just seems worth some more digging around.

Of course I could easily be wrong, it wouldn't be my first time

[Joe L.]

Re: 70 LT1 suspension resto dilemma

Wow, I wouldn't be in a hurry to break up that car just yet, it may very well be a piece of history that needs exploring. I've been banging away on my 70 LT-1 for a good while which keeps me reading more and more and, while I don't pretend to be an expert like many here that have studied them more and even worked the line building them, there is one thing I have come away with...I just don't trust GM's record keeping from that era, it was just too sloppy and, with only gut feeling as evidence, think there was a whole lot of "wink and a knod" dealing going on when it came to equiping Vettes back then. There seemed to be a number of dealers, being the salesman they are, that could work around any "rules" to get a car made the way they needed to make a sale (I never under estimate a slick salesman). It would really be a shame to disassemble a piece of history without realizing what it truly is. Who knows, maybe the dealer helped the Vet out and put the power windows in or conned the factory into it. Just seems worth some more digging around.

Of course I could easily be wrong, it wouldn't be my first time

Wayne----


I agree. I have a strong feeling that the J-56 brake set-up on this car is original to it. I don't think it was added. Unless the car was used for racing purposes sometime during its life, I don't see why someone would add J-56 and F-41 to a car. If it was used for racing at some point, there ought to be other modifications, the vestiges of which would so-indicate.

Also, 1971 seems to be a year that quite a few "strange things" occurred as far as Corvette builds were concerned.

[Joe L.]

Re: 70 LT1 suspension resto dilemma

I bought a 70 LT1 last year with an interesting history. It was a special order by a California dealer for the original owner who was a Viet Nam vet at the time. He ordered the car Laguna grey and bright blue interior with what he called the ZR1 package in his letter. Now I'm sure the car is not a ZR1 ( car has a radio and electric windows), but I am curious about the suspension. In the original owners letter he talks about the special brakes, etc on the car. The car came to me with dual pin brakes ( #5469588 ), heavy duty sway bar (15/16) rear spring ( 7 leaf ) and HD front springs. I only have a p.o.p. and no way to prove HD suspension other than the letter, so should I ditch all this stuff and just do the resto with standard parts? I want to do as well as I can with this car because the drivetrain is all there and the color combo is rare. What do you think?

Kim----


There are a few other things I'd like for you to check for us on this car so that we might all learn some more about it:

1) What radiator is in the car? Is it the copper/brass with integral filler on the right side tank and using a plastic fan shroud? Or, does it have an aluminum radiator with external aluminum supply tank and a round metal or no fan shroud? If it's an aluminum radiator, what part number is stamped on top of the radiator?

2) What bellhousing is on the car? The part number will be embossed on the side of the bellhousing. It will be either 3899621 or 3858403;

3) This one will be tough to check but it will be VERY important. Check the forging numbers on the lower rear shock mount shafts. These are lightly embossed and may be difficult to discern. They will be on the unmachined portion of the shaft. A photo of a typical shaft with the APPROXIMATE location of the forging number is shown below;

4) Please check the casting numbers on each of the 2 inner front calipers as I have previously described. Pay particular attention to the last digit. Also, check to confirm that there is only one brake line fitting boss on the calipers as shown in the photos of the caliper half I have pictured above.

If you can get the above information, I think we'll know more about this car.

[Wayne B.]

Re: 70 LT1 suspension resto dilemma

A radio and power windows can be installed easier than dual pin brakes, heavy duty sway bar, 7 leaf rear spring, and HD front springs. What indications do you have that it is NOT a ZR1. Does it have the original engine? If so, what is the suffix? If not, what is the suffix from the POP?

I can see this scenario. When you consider that the ZR1 had nothing in the way of creature comfort but had a desirable power package I could see someone bugging a dealer to get the windows and radio added on. Those cars carried some nice profit margin and I seriously doubt Chevrolet would turn down an order over a radio and power windows. Think about it "we can leave off power steering, radio, air conditioning, etc and still charge the fools more!". Again, that gets into my distrust of GM record keeping. I could see someone in the office just fill the order as a special order car without bothering to check off that it was a ZR1. I don't think for one second that an office full of order clerks would care two cents about cross referencing what was on the car vs what was an "official" ZR1 to make sure the tally for ZR1's going out the door was correct...especially to accomodate a bunch of restorers forty years down the road. To them it was just another special order, another folder in their "in pile" to get moved across the desk to the "out pile" before five o'clock and happy hour. How hard could it be for a dealer? Start with an LT-1 order sheet and just check off the upgrades individually that make the ZR1 package adding ammenities like a radio and power windows. Presto! No ZR1 forms to get cleared by GM.

I'll bet dollars to donuts that wouldn't be the only time that happened either. Now I can see the argument that a ZR1 is defined by the exact package that it called for but I'll bet there are more out there that dealers skirted the "rules" on to make a sale. That's why I've always thought that the incredibly low number of ZR1's reported to have been produced might be "technically" correct but I wonder what affect dealer shenanigans would have to inadvertently make a whole different tier of cars. When I was in high school I had a friend whose father owned a large Pontiac dealership and I spent enough time there to know those guys are pushing tin (or in this case fiberglass) and not about to let anything get in the way of a sale...rules? what are rules? We're only interested in sales! And of course there is a very large manufacturer that is more than happy to take the extra cash.