Dodge Challenger Drag-car build.

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Mopar 440
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Re: Dodge Challenger Drag-car build.

Post by Mopar 440 » Fri 12 Oct 2012, 08:44

Managed to get my hands on other Powerglide case, and rebuilt the transmission again. We figured the case I had must have been a weak casting, as the Powerglide case in Mark's Camaro, that is also stock, lasted and he goes quicker than me. (hell, his doesn't even leak oil after 4 years of use and abuse) We re-checked the pump pressure after installation and we were withing spec between 180 to 250 psi.

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We removed the rocker shaft etc, to re-torque the heads as it been through some heat cycles. Got to love removing an intake manifold with no water passages. 8 bolts, fuel line and some wires, job done.

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WhiteRhino
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Re: Dodge Challenger Drag-car build.

Post by WhiteRhino » Fri 12 Oct 2012, 13:51

I have 2 questions just for my education. I think you might of mentioned it earlier in the tread but p[lease indulge me:

1. Why is a ford 9' diff such a sought after item?
2. What is the purpose of filling the water passages?
Ryno
-----------------------------------------
No car at the moment... Looking for a running Chev C10

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Mopar 440
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Re: Dodge Challenger Drag-car build.

Post by Mopar 440 » Sun 14 Oct 2012, 12:57

WhiteRhino wrote:I have 2 questions just for my education. I think you might of mentioned it earlier in the tread but p[lease indulge me:

1. Why is a ford 9' diff such a sought after item?
2. What is the purpose of filling the water passages?
1:
We must remember that the 9" diff was origionally designed and built for pick-up trucks, that Ford used from the parts bin to fit into passenger cars. GM had the Dana rear end that was used in the pick-up trucks, but used the lighter but weaker 10 or 12 bolt diffs in there passenger cars. Thus, in the earlier days of drag raceing, the Ford car that makes say 500hp and the Chevy guy in his 500hp car has got a greater chance of of losing due to diff failure. Now we know nobody likes losing, the Chevy guys had an option to upgrade to a more expensive Dana diff or the plenty and cheap 9", so most went for the latter.

The design of the center section of the 9" is also better as you can remove the 3rd member from the car, work on it on your workbence to repalce parts and to set pre-loads. The 10 and 12 bolt has got the rear cover, thus when working on it, you need to remove the whole diff from the car, or work underneath the car.

The 10 and 12 bolt diffs also came stock with the C-clips on the inner side of the side shafts, so when you break a side shaft, the whole wheel assembly and the side shaft comes out of the diff. The Ford 9" uses the bearing retaining clips on the outer side housing ends, so if you snap a side shaft off the wheel will stay on.

In my opion, engineers design components for a car with a safety margin worked in, but is always limited to that nasty four letter word....COST. So at stock usage, any part that came with the car is good enough, but as soon as you start adding power to any car, that safety margin on the OEM part gets exceeded and failure of any part is a given.

2:

This cross section picture of a block showing the water passages filled with Hard Block. There is two options to do this, as the picture shows, leaving the top of the water jacket open to allow for cooling by the combustion chamber where all the heat is generated due to the combustion process, or fill the water jacket to the top for complete strenth, but no cooling. Guys running alchahol engines can use this as they do run cooler, and the alchahol assists in the cooling process.

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On a high HP engine, on the power stroke that forces the piston down the bore, the force also wants to lift the head of the block (use stonger headbolts),wants to blow the head gasket out (use better head gaskets) and lastly pushes against the sleeve as well, flexing and deforming the cylinder wall that causes blow by and compression loss. So by stiffening the cylinder wall you gain horsepower.

This process also dampens harmonic vibrations.

The bottom end is also becomes more rigid and stronger, preventing the dreaded "cap - walk" between the main caps and the block.

Remember, this is a drag race option only, as the cooling is effected by this.

Hope this helps.

Simon
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Johann65
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Re: Dodge Challenger Drag-car build.

Post by Johann65 » Sun 14 Oct 2012, 20:09

Hope the other members take note about the Powerglide Box. I am a firm believer!! :D :D My Powerglide is untouched since 1965 and still on the go!!
Member No: 209
Ah! Yes I remember it well! (Only GM's!)
1966 Opel Rekord L CLASSIC SEDAN Current Project

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Mopar 440
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Re: Dodge Challenger Drag-car build.

Post by Mopar 440 » Tue 16 Oct 2012, 09:08

Johann65 wrote:Hope the other members take note about the Powerglide Box. I am a firm believer!! :D :D My Powerglide is untouched since 1965 and still on the go!!
Thanks Johann

Yes, we also like the Powerglide, but I just had real bad luck with mine. Stay tuned to what we ended up doing.

Simon
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Mopar 440
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Re: Dodge Challenger Drag-car build.

Post by Mopar 440 » Tue 16 Oct 2012, 09:16

Finally fitted the side windows. On any build there is one item that you know is a kak job (because it has no door frame and is curved), so you procrastinate till the bitter end. This was it on my car, but it really came out well.

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zahistorics
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Re: Dodge Challenger Drag-car build.

Post by zahistorics » Wed 17 Oct 2012, 03:39

Mopar 440 wrote: ....The design of the center section of the 9" is also better as you can remove the 3rd member from the car, work on it on your workbence to repalce parts and to set pre-loads...
This means the front of the diff unbolts off the axle complete with the crown wheel like so:
9inch.jpg
9inch.jpg (24.28 KiB) Viewed 1674 times
Also quite nice if you are a circuit racer and want to change the final drive ratio.

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Mopar 440
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Re: Dodge Challenger Drag-car build.

Post by Mopar 440 » Thu 18 Oct 2012, 20:14

Correct, thanks John.

Entered my first Nationals. Was nervous as hell so we decided that I do a warm-up run with no burn-out and on a unprepared track. Ran a calming 13.8sec @ 180km/h.

My first run and proper burn-out followed. I was amazed how quick the car revs up and the ease it turns those rear tyres whilst standing still. I think I overdid it a bit, but they were warm after this.

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I launched of the trans-brake and did a 11.41sec @ 204.20km/h, the car felt strong and stable, but as I went through the lights, the car suddenly started to vibrate excessively.

The normal pose of a new drag racer after a run.

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Once again the transmission cracked on the reverse side (exactly as previous), but the major concern was that I bent the prop shaft and broke the transmission tail housing.

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This is were I was absolutely amazed with the help and advise of fellow Drag racers, really trying to solve our problem, as we were a bit confused as how this could have happened.

This is when Gavin Wilkins, the old master of his craft told me: Check your pinion angles, something is wrong, and with that a new can of worms was opened.
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Mopar 440
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Re: Dodge Challenger Drag-car build.

Post by Mopar 440 » Mon 22 Oct 2012, 15:52

We always assumed that on a drag car, the pinion angle is 2 deg down, and we all know what assumption does..... Most of the internet sites agree with this , but none of them says why??? The biggest problem is that pinion angle is interpreted differently, i.e. angle of pinion relative to what, the floor, the prop shaft, your cars stance, the angle of the engine and gearbox, the type of suspension, i.e. stock, slapperbars, ladder bars or four link????? After a couple of days trying to find that answer, as it is very difficult to explain verbally, I reverted to Google images and found this picture that just explains it.

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My car transmission angle was 3deg down and the diff was also 2deg down, and this caused the prop shaft to skip like a skipping rope, bending it when the inertia became too great. We could no change my transmission angle because of space constraints , so we moved the diff angle to 1 deg up and that sorted that problem out.

Oh, and why do most people say that a drag car pinion angle is 2deg down, is because when you build a tube type race car, you will mount the engine level (0deg),
but this is a back halved car, so that rule does not apply.
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Bigblock496
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Re: Dodge Challenger Drag-car build.

Post by Bigblock496 » Mon 22 Oct 2012, 18:50

It was amazing to me that no one I spoke to fully understood pinion angle and its effects! The "2° pinion down no matter what" rule that you always read in magazines can be confusing,and it caught us out! We set the car level and set the pinion at 2° down relative to the floor,not knowing that the engine should now have been at 0°,but the engine was at 3° down! Had this been a street car with normal leafsprings,we would have been spot on,because a streetcar gets set up at 4° down pinion angle,and under load,a leafsprung car will would have given us our 2° up,matching our gearbox down angle! Simple,no? :(
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