1969 Z/28 proportioning valve

[VI009DZ]

I have an early '69 Z (10C).  Nowhere on the car do I find a proportioning valve for the rear brakes.  From what I have read, they were all on the subframe rail under the drivers seat.  This car does not have one, and also shows no signs that any brake lines were tampered with in the past.  There is a remanufactured master cylinder on the car.  Did all '69 Z's, (or all disc brake cars for that matter) have the porportioning valve on the subframe, or was it a later addition to 69's?  Thanks.

[rsatz28]

http://www.camaros.org/TopicsofResearch.shtml

I have a 11A 68 built and I do not have.

A portion from the link:

Usage of the valve was not consistent. 1967 Camaros receiving the valve were all models with C60, all SS396 models and NOR-built Z28s (at least the later ones). However, the 1967 LOS Z28s did not get the valve. At the start of 1968 the C60 rationale was dropped and the application of the valve generally changed to all models with 12-bolt axles. One exception is that starting in mid-1968, NOR Z28s stopped using it for a year, starting again in mid-1969. And note that usage of the valve on 67-69 Camaros was apparently not related to J52 disc brakes.

Different opinions have been expressed on whether or not it was effective at reducing stoping distance but CRG has not seen any comparison braking data. If it was effective, why wasn't it used on all models, and why was Z28 usage irregular?

Several have suggested that this valve might have been a reaction to a consumer lawsuit in prior years, and therefore, it's application on vehicles may not have been entirely rational. This remains undocumented speculation. In the meantime, we are searching for more data on this valve and on cars that have it (and don't).

[crossram]

I think the reason they got them in 1967 with the C60, was because of the addition weight in the front end. I have a 1967 with the valve on the subframe with A/C.

[sam]

I have an 11 D car with original lines and no valve.

[x77-69z28]

i have an 05A nor x77 car. it has the valve. a friend of mine has a 01A nor x77 car. no valve. i always wonderted about that myself.

[VI009DZ]

Thanks for the info fellas.  I was wondering.  Everything else on the car points to a true Z, so this had me a little puzzled.  It's one of those things that the less informed people point out and say "clone" unless the car has it.

[jdv69z]

I have a 10B 69 Z with no proportioning valve. I replaced orginal brake lines myself, and there was and is no valve under the front seat. Who says they all had the valve? Probably the same ones who say they all had tachs and guage package!! And that they never made a Rally Sport Z!! And that there was another gunman on the grassy knoll!!!

Jimmy V.

[KurtS]

Jimmy,
Yup, that's why that's on the site.
One exception is that starting in mid-1968, NOR Z28s stopped using it for a year, starting again in mid-1969.

[3Zs]

I would have sworn there was a gunman on the grassy knoll.

[RamAirDave]

The disc brake cars were inconsistent about the usage of the valve.

Have there been any original front drum cars that had it?

[KurtS]

Yes. Some drum brake 10 bolt cars have had it too!

[RamAirDave]

Yes. Some drum brake 10 bolt cars have had it too!

Very intersting, Kurt.  I guess that pretty much shoots down the valve as being any kind of "tell-tale".

Ive seen front disc cars without, but not a front drum car with.

[69 4 Speed]

Yes. Some drum brake 10 bolt cars have had it too!

My O2B NOR drum brake 10 bolt car has the proprotioning valve.

[HokieZ28]

Just For Your Records My 03B 69Z With Front Disc Has The Valve .
Thanks Ben

[68Zproject]

My 05D 68Z does not have the valve under the driver's door.  I had a 68ss that did and it had non-power drums all- around.  I can't remember when it was built, but guessing it was a lot earlier than the Z.