[Mjohnson23]

Ok I have accumulated everything to do the swap in my car with the exception of the frame bracket for the Z bar which I can fab in our shop no problem but I do have a question about dimensions. Like distance from frame edge to the 90 degree turn up the the Z bar attaches to and the height off the frame to the slot. I can position it correctly and tack it in place with everything in place and trans set. I also have another auto trans shifter plate i cut all the stuff off of and got a Early GTO shifter cup im gonna marry into it (Wish me luck). The last question I have is on the flywheel. The set up I bought which had everything from a 69 GTO, Bellhousing, M-21 muncie, Shifter, Z bar assembly with the GTO frame bracket, Pedals and floor board perch in perfect condition. He gave me two flywheels, both with the 2 3/4" center hole and I wondered how do you identify and date them? Do they all have the small offset in balance made into them? I know Pontiacs are internally balanced and 0 at the crank but they had to have my auto flywheel to balance it dead on as the rear counter is a little off and thats why the flywheels only go on one way. So do they all have the small counter balance drilled out of them? i noticed one flywheel has 3 or 4 drill marks where as the other only has 1 drill mark. Just wanna make sure i clean up and surface what will work for sure lol.

[north]

The frame bracket is a bolt on, the holes should be present in the frame. As for the flywheel just send it out to have it cleaned up and balanced. The drill marks are from either factor or later balancing processes.

One thing to consider is if the flywheel is drilled for a 10.4 or 11" clutch, earlier flywheels typically are only drilled for one or the other (Fbird - GTO 10.4" and fullsize 421-428 11") while later ones are drilled to receive both.

[Mjohnson23]

Yes I realize its a bolt on but I dont have one nor can it be bought from what ive read and heard on this forum. The GTO frame bracket is completely different and I guess I could drill holed in the top of the frame and use it but looks like it would need spaced up to be as high as the factory GP piece. Thats why im asking if someone has one can the shoot me some dimensions and ill make one to use.
Thanks, M. Johnson

[north]

I had a 4spd 69 GP back in the 90's and I checked last night if I had any photos of that area but no luck. I would avoid welding on a frame at all costs, the holes should be there (I see them on the frame of my current automatic 69 GP) and build a bolt on bracket that gets the z-bar horizontal and perpendicular to the length of the car.

I think if I ever found a nice console bezel and cup I'd make mine a 4speed. I even have an NOS 69 GP only 4speed shift knob.

[wldthng72]

Hope this helps

[wldthng72]

and this

[Mjohnson23]

wldthng72 thank you so much!! Thats exactly what I was looking for to reference. That gives me all i need dimensionally to fab one. Thank you!

[69GP428HO4SP]

Started having some of these made, had to make final adjustments for the correct Z bar height.

[Mjohnson23]

How much 69GP? Would save me a lot of time, trial and error lol

[Doug]

Originally Posted by Mjohnson23

Ok I have accumulated everything to do the swap in my car with the exception of the frame bracket for the Z bar which I can fab in our shop no problem but I do have a question about dimensions. Like distance from frame edge to the 90 degree turn up the the Z bar attaches to and the height off the frame to the slot. I can position it correctly and tack it in place with everything in place and trans set. I also have another auto trans shifter plate i cut all the stuff off of and got a Early GTO shifter cup im gonna marry into it (Wish me luck). The last question I have is on the flywheel. The set up I bought which had everything from a 69 GTO, Bellhousing, M-21 muncie, Shifter, Z bar assembly with the GTO frame bracket, Pedals and floor board perch in perfect condition. He gave me two flywheels, both with the 2 3/4" center hole and I wondered how do you identify and date them? Do they all have the small offset in balance made into them? I know Pontiacs are internally balanced and 0 at the crank but they had to have my auto flywheel to balance it dead on as the rear counter is a little off and thats why the flywheels only go on one way. So do they all have the small counter balance drilled out of them? i noticed one flywheel has 3 or 4 drill marks where as the other only has 1 drill mark. Just wanna make sure i clean up and surface what will work for sure lol.

Typically, a stock automatic flexplate would have 3 "balance" holes drilled in it roughly opposite the narrow-spaced mounting bolt space. It sounds like when you had your engine built you used your STOCK automatic flexplate when they balanced your engine.

It appears that your engine is balanced just like a stock factory engine. (UNLESS, the machinist modified the stock automatic flexplate's balance.) This indicates that a STOCK manual flywheel would be needed.

Typically, a stock manual flywheel has "balance" holes drilled in it roughly opposite the narrow-spaced mounting bolt space.

Typically, stock manual flywheels have a "date code" on them similar to other engine components. It's location and marking should resemble the picture below. I assume the additional number in the picture is a part/casting number.

Posting pictures of your flywheels would be helpful.

Mid-60's Pontiac "big cars" used "long tailshaft" trannys. 69 GTO's used short tailshafts. I don't know what a 72 Grand Prix used but it may be something you want to check out.

I have read that, in 1968 GM went back to cast iron cases for most Muncies, with aluminum cases used primarily for high-performance models--such as most Corvettes, Pontiac Ram Air models, Olds W-30 cars, etc. I assume that a "regular" 1969 GTO would have a cast iron case. Which is yours?

['ol Pinion head]

Originally Posted by Doug

Mid-60's Pontiac "big cars" used "long tailshaft" trannys. 69 GTO's used short tailshafts. I don't know what a 72 Grand Prix used but it may be something you want to check out.

I have read that, in 1968 GM went back to cast iron cases for most Muncies, with aluminum cases used primarily for high-performance models--such as most Corvettes, Pontiac Ram Air models, Olds W-30 cars, etc. I assume that a "regular" 1969 GTO would have a cast iron case. Which is yours?

All Muncie 4spds will have an aluminum case & alum tail shaft housing. The 4spd '69-71 GrandPrixs used same case & tailshaft housing Muncie 4spd as same year GTO. With the correct shifter handle & shifter, linkage, Z-bar, & shifter mtg plate, once you fab the z-bar mtg bracket to attach to the frame you should be on the way.

[Doug]

Originally Posted by 'ol Pinion head

All Muncie 4spds will have an aluminum case & alum tail shaft housing. The 4spd '69-71 GrandPrixs used same case & tailshaft housing Muncie 4spd as same year GTO. With the correct shifter handle & shifter, linkage, Z-bar, & shifter mtg plate, once you fab the z-bar mtg bracket to attach to the frame you should be on the way.

Thanks for the commentary about the Muncie cases.

I had some question about the "cast iron" case when I read about it in an article in the old PONTIAC magazine. I cut the article out and saved it when I read it quite some time ago. I don't know what issue the article was in but part of the article is as shown below. The part about the cast iron case is the last paragraph on the page which reads:

"...In 1968, however, GM went back to cast iron for most of the Muncie gear-case production. In the 68 to 70 period, the aluminum cases were used primarily for high-performance models--such as on most Corvettes, Pontiac Ram Air models, Olds W-30 cars, etc...."

[Mark Stephens]

Have you made progress on your conversion? I'm planning a conversion on my 72 as well.
Thanks
Mark

[brucee70]

Originally Posted by 69GP428HO4SP

Started having some of these made, had to make final adjustments for the correct Z bar height.

All the pics in this thread are very nice ...!
8 or 10 years ago when Steve Newman from Michigan was doing the complete resto on his Black 70 HO 4spd he borrowed the extra bracket I had picked up from a junk yard 4 speed car and had a handful of copies made ....somewhere in my shed I have a few "extras" as part of the deal he gave me a few ...:-)