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 Post subject: 2 speed shift rpm drop
 Post Posted: Tue Mar 10, 2009 9:57 am 
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What kind of rpm shift drop do you guys have with your 2 speed glide combo's, and what 1st gear ratio do you have???? and what do you shift at per your rear gear and tire size? What is an average drop in rpm also? Thanks.

John

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 Post Posted: Tue Mar 10, 2009 10:44 am 
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Not exactly sure what you're looking for here but here goes.

Tire rollout is 106 inches. Rear gear is 5:14. Planetary is 1:80. Converter flashes to about 5900+/-. Gear change is 7600RPM (2.39 seconds into the run) and that falls back to just over 6200RPM at the shift (2.7 seconds into the run) and engine RPM is at 7200 at the stripe and is 126+ MPH.

Which means that my car probably needs a 1:65 planetary and a 5:57 rear gear with this tire I'm running now. Scott's car is trapping around 7600 with the same gear and stuff but with a 101 inch rollout tire. Yeah, it makes that much of a difference!

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 Post Posted: Tue Mar 10, 2009 3:31 pm 
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I am looking for the rpm drop between the 1-2 gear change Ken, and looks like yours drops 1400 rpm's, THAT'S what I'm looking for, Thankyou sir =; =; =; How tall a tire do you run??

I was looking at Billy Shope's calculator page and was playing around with it a bit, cool stuff, but like his comments say, the et may and will be off due to the calculation used, but it get's you close, but not in my case O:)
I am trying to decide which rear gear to go with running the 33 tall tire, my 1.80 first gear and my engine that can rev to 7800 or higher, well, when it had the 4.88 gear and 30 tall tire, and since I got my conv. reworked, it dropped about 200 rpm's with just that work done, than I changed the rear gear from a 4.88 down to a 4.56 and went about 7200 at the stripe, so I have more engine to use and the higher rpm's is where my engine likes to eat at \:D/

The shift point really makes a change on his calc. page when you start changing it, and also the gear ratio, so I am trying to match the gear, to the new tire size to get around 7600 rpm's or higher when I cross the stripe. I have close to a little over 700 ponies at the wheels, and not sure on the torque by the time it hits the trans, but on my pc dyno info, it shows around 650ftlbs at around 5000 rpm's where my conv. stalls at, so it's either a 4.88 and shift above 7000 rpm's or the 5.13 and shift a little lower, but I can play with both variables to get where I want to be.
Thanks for your reply Ken. ;-)

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 Post Posted: Tue Mar 10, 2009 6:53 pm 
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Tire is marked as 33" dia but if you do the math for 106 rollout it comes up larger than that.

106/3.1416=33.740 dia. A true 33 inch tire is about 104" rollout. 33x3.1416=103.672

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 Post Posted: Tue Mar 10, 2009 6:57 pm 
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Ken0069 wrote:
Tire is marked as 33" dia but if you do the math for 106 rollout it comes up larger than that.

106/3.1416=33.740 dia. A true 33 inch tire is about 104" rollout. 33x3.1416=103.672




Just got my DO6's and mounted them up and I asked for a short set if they had them and when I measured them with
8psi in them it was 104 1/4 for one and 104 3/8s for the other....Im happy with that..Now we need some nice weather
so I can go =; =; =; ...............

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 Post Posted: Tue Mar 10, 2009 7:32 pm 
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Mine shifts at 6700 and drops to 6000 on the shift. I run 4.88's with basically a measured 30" tall tire and 1.76 planetaries.

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 Post Posted: Tue Mar 10, 2009 8:41 pm 
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16x32 tire
5.0 gear
Glide with 1.80 first
Converter flashes to 6750, shift at 7600 falls to 6950 cross the 1/8th mile stripe at 7600, cross the 1/4 at 8100


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 Post Posted: Tue Mar 10, 2009 10:22 pm 
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What MPH is that thing running Scott? Did you ever figure what % the DS RPM is of the engine RPM? Converter slip %?

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 Post Posted: Tue Mar 10, 2009 11:19 pm 
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Didn't do the math.

I'll pull up some logs tomorrow.


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 Post Posted: Wed Mar 11, 2009 6:48 am 
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us7race wrote:
Mine shifts at 6700 and drops to 6000 on the shift. I run 4.88's with basically a measured 30" tall tire and 1.76 planetaries.


What stall convert. and diam. do you run????

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 Post Posted: Wed Mar 11, 2009 7:26 am 
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Ok guys, Poll question without the poll,
Which gear ratio, with my 33 x 16 tires, and 3600lb chassis will give me the best 60 ft's and et/s with my 1.80 gear ratio, 5000 stall 9" conv., and now being able to launch closer to my stall at around 4800 rpms????? and I have 2 choices on gears, 4.88, or the 5.13. Thanks again for your input guys also. =D> =;

John

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 Post Posted: Wed Mar 11, 2009 10:24 am 
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Hummm, my 3459lb Studebaker with a 5:13 and the "good" engine along with a 33" tire was trapping at around 7600 to 7700 @134MPH. Prolly needed a 4:88 for quarter mile but since I most always ran eight mile I just left it with the 5:13. 4:88 would be too high for eight mile and actually 5:13 wasn't low enough for the short tracks. Prolly could have run a 5:57 in eight mile only but who wants to be setting up a Dana 60 every time I switched track lengths? NOT ME! So the 5:13 was kinda in between and I could run both if I wanted.

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 Post Posted: Wed Mar 11, 2009 5:07 pm 
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Elkyman wrote:
us7race wrote:
Mine shifts at 6700 and drops to 6000 on the shift. I run 4.88's with basically a measured 30" tall tire and 1.76 planetaries.


What stall convert. and diam. do you run????


My converter is a 9.5" and it will hit 6000 if I pull the limiter out.
Do you think this is bad?

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 Post Posted: Wed Mar 11, 2009 9:30 pm 
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us7race wrote:
Elkyman wrote:
us7race wrote:
Mine shifts at 6700 and drops to 6000 on the shift. I run 4.88's with basically a measured 30" tall tire and 1.76 planetaries.


What stall convert. and diam. do you run????


My converter is a 9.5" and it will hit 6000 if I pull the limiter out.
Do you think this is bad?


Badd A$$ if you ask me \:D/ \:D/ \:D/ , wow though, a 9.5 diameter???? I would have picked your truck to have at least an 8 inch in it!!! How much does your truck weight???? and you run a small block right ?? Now I could see your truck with a 8 inch easily, or, maybe a 9" if your over 3000lbs, but what do I know :- I know my 3600LB elky loved an 8" when I tried one from a friend and went 2 tenths quicker than the Elky had ever been, so why don't I have an 8"? cost right now, and if I had another $1000. I would buy a 7" and let er rip, but then I would need 2 more convertors, one in the trailer, and one in for repair as I am sure I would eat them up almost every couple of weeks with my weight =P~ but do they work in a heavy car ;-)

Thanks for your input and your truck launches very well if I might add, nice job. =D> =D> =D>

John

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 Post Posted: Thu Mar 12, 2009 5:10 am 
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Yes a small block 422 weight is 2865 I bought this converter from Edge racing. They tell me you can't get the effeciency out of an 8" verses a 9 or 10" converter. I don't really buy that now but the converter has done me pretty good. I wish I had a 8" to test the threory of which one runs a quicker E.T..

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6.07@110 on Alcohol Injection with a 4-link 4-6-12
Best 60' 1.2537 Alcohol Injection 4-29-11
Thru the Mufflers!!


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