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Messages - rich69rs

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The question is why are the U-joints out-of-phase?

The answer is for reducing vibrations.
Graph the power through a single U-joint and a sine wave is drawn. The joint speeds up, positive arc, and slows down, negative arc.
Add another U-joint and its power graph will have the same sine wave.
Add the two sine waves, if they are in-phase on the same shaft, and amplitude doubles, meaning the resultant twist is noticeable.
By offsetting one joint by 30į, decreases the amplitude of the associated twist, less vibration.
Now, driveshaft's having been built forever, and 1st Gen driveshaft's are different from typical design, may be due to the extreme angularity of drivetrain design on Camaro, i.e., wheelbase, length of shaft, OD and wall thickness, and critical speed of driveshaft.

Critical speed is important - it is rocket science.

I have to disagree - thatís not how a double Cardan joint (U-joint) works.  Refer to page 3, 3rd post of this thread and search : driveshaft, rich69rs for other posts where this has been discussed previously.

I have my theory as to why Chevy did this - but since the forum hasnít pursued the question seriously,  I havenít either.  Of all the driveshafts built by all the auto makers, over all the years, Ď69 Camaro, SB, TH350, manual, and Powerglide got offset yokes, yet, as I recall BB w/TH400 transmissions didnít???

As far as critical speeed (resonance) goes, offsetting the yokes will definitely stiffen the driveshaft and shift a natural frequency(cies) up - but at the expense of proper operation of a double u-joint system which is designed to keep the included angles of the driveshaft equal at all times.

With offset yokes, the included angle between the differential and the driveshaft will be different at all times from the included angle between the driveshaft and the transmission.  Stiffer driveshaft system? Undoubtedly.  Ideal for loading on either the diff or tans?  Not so much.  I modified my driveshaft to in line yokes back in 1991. 

Restoration / Re: complete brake booster for drum brakes: parts numbers
« on: September 08, 2017, 01:45:08 AM »
I would concur with the suggestion to check with NAPA for a rebuild kit.  That is where I got my rebuild kit.  Disassembly is easy.  A little air into the port in the bottom of the reservoir will push both the primary and secondary pistons out if they are stuck.  I was lucky with mine - did not require resleaving.  Just a clean up and light honing of the cylinder with a brake cylinder hone.

Biggest issue was "gunk" which was the result of moisture entering the system.  I am a very big fan of DOT 5 silicone brake fluid.  Eliminates that problem and if you happen to dribble a little on a painted surface, no problem.  Pic shows my master cylinder after disassembly.  Also, don't forget that there are check valves behind the brake line connections to hold some pressure in the lines when your foot is off of the brake - keeping the shoes just barely in contact with the drums.  That way when you push on the brake pedal, the shoes don't have to move as far to fully engage the drums.

Good luck


Restoration / Re: complete brake booster for drum brakes: parts numbers
« on: September 06, 2017, 06:18:07 PM »
These might be helpful - booster and master cylinder p/n, etc. given in an embedded link in the first link.  2nd link has other forum links that may be helpful.


Restoration / Re: Norwood stickers
« on: September 05, 2017, 11:00:10 PM »
Looks like a door glass warranty adjustment sticker:

Another example from my passenger side door - 69RS; 01C Norwood build

Originality / Re: trunk lid rear emblem with factory D80 spoiler
« on: August 28, 2017, 07:25:29 PM »
I believe also that this spoiler was added, especially on an RS. I'm just wondering if yes or no, I'll put a rear "Camaro" emblem forward of the spoiler.

Rear spoiler on my '69RS was a dealer (or someone) installed item after the car left the factory.  During the body/paint work fall 2013-spring 2014, I had the shop doing the work add the deck lid "Camaro" emblem.  IMO adds a very nice touch.


Garage Talk / My First Camaro - What was Yours?
« on: August 17, 2017, 11:40:54 PM »
Cleaning out some old documents today and came across this.  It is the dealer invoice copy of the first Camaro I owned - a 1976 sports coupe.

I had graduated from college in late Aug 1975 and took my mechanical engineering degree to my first job in Deer Park, TX (Houston suburb - on the industrial/ship channel corridor).  Within a month I had purchased my first Camaro from Timmers Chevrolet in Pasadena, TX - a 1976 Camaro Sports Coupe - and although from a performance standpoint, she couldn't get out of her own way - she was mine - all mine, my first Camaro.  I clearly remember that I had negotiated an out of the door total cost (car, tax, title, license, etc.) for $5,000 - and I felt pretty good as a brash 22 yr old.

The poor car had a horribly detuned, EGR equipped, 305 CID engine with a Rube Goldberg assortment of hoses and vacuum lines running all over the place - early attempt at emission controls.  The heat riser valve was actually operated via a vacuum canister mounted up on the passenger side of the engine that either left the valve closed or opened it based on vacuum to the canister.  What a mess.  The 305 was rated at 140 HP at the flywheel, and if I got 90 to a 100 HP at the rear wheels I was lucky.  Top speed, flat out, pedal to the metal, long straight run of highway was 90-95 mph.  The mid to late 70's was not the high point of Detroit manufacturing prowess to say the least.....but she was mine all mine.  A pretty car, by mid-70's standards with Firethorn Red Metallic paint.

I kept that car until mid-1988 when a growing family and other transportation needs dictated that it was time to sell - which I did via a private sale to a lady for $1500.

When I sold the car, the door hinges were in need of replacement.  That car had some big, heavy doors on it and by 1988 the hinges were showing the strain of supporting those heavy doors.

All good fun.



First attachment is from the 1969 Camaro Factory Assembly Manual, Section UPC12, A7.  It shows the routing for the wire from the temp sending unit.  It is a single break out lead from the main engine wiring harness. 

Second pic is from 2004 when I was finishing up the front sub-frame, engine & trans on my '69 RS.  You can see the wire to the sending unit.


General Discussion / Re: 1969 Camaro Over Heating issue
« on: July 22, 2017, 12:28:41 AM »
I'm just throwing this out there as it happened to me.  My car started running hotter than its regular norm and started dying at a stop and being really hard to restart.  It usually didn't restart until it sat and cooled down awhile.  It turned out that the heat riser valve in the passenger side exhaust manifold had frozen shut. 

My suggestion is that you throw the heat riser valve out in the snow and replace it with a "donut" in order to avoid the very problem you mention.  I got rid of mine a long time ago. Only thing I do to compensate is a few more seconds at idle after starting cold.

Heat riser valves you get today from anywhere are junk IMO and you are just asking for trouble if you install one.

Maintenance / Re: Temp too hot?
« on: July 12, 2017, 02:10:41 AM »
The following links discuss where I made a few simple mods to improve the cooling especially in stop and go traffic, especially at altitude (4500 feet), especially with today's gas, especially with marginal cooling systems from the factory originally (ask anyone who has or has had a mid-year big block Vette), etc....

Originality / Re: Pulley diameters - anyone have these pulleys
« on: March 31, 2017, 02:43:52 PM »
The list of "the missing" is definitely getting shorter!

General Discussion / Re: RS Head Lamp Covers
« on: March 23, 2017, 09:32:19 PM »
....and this Word doc.

General Discussion / Re: RS Head Lamp Covers
« on: March 23, 2017, 09:26:29 PM »
This topic has come up several times in the past.  If you search the site, you should find more than one post which addresses this topic with various diagrams, etc.

As a starting point, see attached and following post below.


Originality / Re: Pulley diameters - anyone have these pulleys
« on: March 23, 2017, 09:19:34 PM »
3956664            69
 1969 SB Base V8; CF code
6-3/4" OD, by tape

Originality / Re: Pulley diameters - anyone have these pulleys
« on: March 23, 2017, 09:18:58 PM »
3956664                   69
 1969 SB Base V8; CF code
6-3/4" OD, by tape

Garage Talk / Re: A Beautiful Day in Northern Nevada
« on: March 02, 2017, 08:28:05 PM »
....a beautiful day continued

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