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Author
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Topic: Gearing question
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65_302
Gearhead Posts: 239
From: Bixby, OK
Registered: Jul 2001
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posted 10-02-2002 12:49 PM
   
What kind of change in 60 ft. time would you expect to see when going to a C4 with 2.43 first gear from a Tremec with a 3.27 first gear and keeping the 4.11 rear end?
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Moneymaker
Administrator Posts: 19704
From: Lyons, IL, USA
Registered: May 99
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posted 10-02-2002 01:09 PM
It all depends on traction. If you had good traction with the Tremec, then expect to lose a bunch. Like .015 or more.
If you spun a lot with the Tremec then it will improve substantially.  ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA/MCA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
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65_302
Gearhead Posts: 239
From: Bixby, OK
Registered: Jul 2001
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posted 10-02-2002 01:33 PM
Thanks Alex for the quick reply. We went from 1.78 to 1.90 (-.012) 60s, so thats about right with your .015. We had good traction with the Tremec and have good traction now with the C4. Would going to a 4.3X or 4.5X rear gear help?
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65_289
Gearhead Posts: 761
From:
Registered: Jul 2001
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posted 10-02-2002 02:23 PM
quote:
Originally posted by 65_302:
Thanks Alex for the quick reply. We went from 1.78 to 1.90 (-.012) 60s, so thats about right with your .015. We had good traction with the Tremec and have good traction now with the C4. Would going to a 4.3X or 4.5X rear gear help?
Ummm... 1.90 - 1.78 = 0.12, not 0.012.
[This message has been edited by 65_289 (edited 10-02-2002).]
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Moneymaker
Administrator Posts: 19704
From: Lyons, IL, USA
Registered: May 99
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posted 10-02-2002 02:26 PM
 ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA/MCA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
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65_302
Gearhead Posts: 239
From: Bixby, OK
Registered: Jul 2001
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posted 10-02-2002 02:46 PM
I know poor math skills is not an excuse, but maybe haste is. Gotta slow down. Sorry for the mistake. Still gotta find the lost time.
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Moneymaker
Administrator Posts: 19704
From: Lyons, IL, USA
Registered: May 99
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posted 10-02-2002 02:54 PM
Yes, 4.56 gears would help the overall ET and the 60 foot. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA/MCA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
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65_289
Gearhead Posts: 761
From:
Registered: Jul 2001
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posted 10-02-2002 06:46 PM
quote:
Originally posted by 65_302:
I know poor math skills is not an excuse, but maybe haste is. Gotta slow down. Sorry for the mistake. Still gotta find the lost time.
Very true.
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steve'66
Gearhead Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-02-2002 08:46 PM
Why hasn't anyone mentioned the converter? Did I miss something?
Oh well, what converter are you running?
It is a very important component with an automatic. Also what c-4 is it, is it a stocker, does it have a tranny brake?
SteveW
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65_302
Gearhead Posts: 239
From: Bixby, OK
Registered: Jul 2001
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posted 10-02-2002 11:13 PM
The C4 has a transbrake and valve body by Art Carr (the real one) and the converter has a 3500 stall. We talked with Mr. Carr and he agrees that the converter is a good match for the engine, rear end and drive train. We also talked with TCIs tech department and they say the converter should be a good match. That's why we ruled out the converter.
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steve'66
Gearhead Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-02-2002 11:21 PM
quote:
Originally posted by 65_302:
The C4 has a transbrake and valve body by Art Carr (the real one) and the converter has a 3500 stall. We talked with Mr. Carr and he agrees that the converter is a good match for the engine, rear end and drive train. We also talked with TCIs tech department and they say the converter should be a good match. That's why we ruled out the converter.
But, If your 60'ers are that much off and the tires aren't spinning the motor is being bogged down. .period. You need a looser converter! Will they re do it?
The converter is the key.
The gearing will help too, but it should 60 at least as well as the manual tranny did. SteveW
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65_289
Gearhead Posts: 761
From:
Registered: Jul 2001
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posted 10-03-2002 09:05 AM
The converter stalls at 3900 on the brake, which I thought meant it's a 3900 stall.
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65_302
Gearhead Posts: 239
From: Bixby, OK
Registered: Jul 2001
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posted 10-03-2002 09:13 AM
Steve'66: I am new to this auto buiness, so can you tell me what you mean by:You need a looser converter!
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mustangboy
Gearhead Posts: 652
From: Ont, Canada
Registered: Mar 2002
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posted 10-03-2002 12:17 PM
I'm confused here.I take it 65-289 and 65-302 are the same guy right?  Anyways I would try to figure out whats with your low trap speed 97ish mph before I did a whole lot of other changes.I hope I'm talkin to the right guy.------------------
1968 mustang j-code sprint.13.69@101 1963Falcon waiting for a rebirth.
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65_302
Gearhead Posts: 239
From: Bixby, OK
Registered: Jul 2001
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posted 10-03-2002 12:31 PM
Mustangboy - its a son/father act. I thought that was a given. Sorry about confusing you. The trap speed was 99.xx with the Tremec and the et was 13.47, with a 1.78 60 ft. launching at 5200. After changing to a C4 it went to 97.xx mph, 13.51 with a 1.90 60 ft, launching at 3000 on the brake and we are sure traction was good. The 60 ft time seems to be the key. Everything in the C4 is supposed to be good stuff. Right down to an Art Carr all billit aluminum, reverse manual valve body, with transbrake. We know we may be choked off a little at the headers (do for a swap this winter), but that does not explain the loss in 60 ft time.
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65_289
Gearhead Posts: 761
From:
Registered: Jul 2001
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posted 10-03-2002 12:44 PM
quote:
Originally posted by mustangboy:
I'm confused here.I take it 65-289 and 65-302 are the same guy right? Anyways I would try to figure out whats with your low trap speed 97ish mph before I did a whole lot of other changes.I hope I'm talkin to the right guy.
The car used to have a 289, hence my user name. The car now has a 302, hence his user name.
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kid vishus
Gearhead Posts: 4538
From: middle of NC
Registered: Oct 2000
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posted 10-03-2002 01:07 PM
Pull the chip once and leave right off the convertor. See if the 60' times pick up. It wont hurt anything (if everything is all good stuff), I ran an entire season without a 2 step using my 'brake, and I had a 4800 rpm convertor then. I think the convertor is too tight also. But, since the et didn't drop much in relation to the 60' loss, it cant be too far off.
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steve'66
Gearhead Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-03-2002 01:40 PM
quote:
Originally posted by 65_302:
Steve'66: I am new to this auto buiness, so can you tell me what you mean by:You need a looser converter!
Looser converter will stall higher and keep your engine in its torque curve.
Try what KV suggested, it'll help get your 60'ers down as long as you aren't spinning.
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mustangzrule
Journeyman Posts: 87
From: Orion, MI
Registered: Sep 2002
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posted 10-03-2002 02:54 PM
Do you have the 60 ft speed? And what is your current shift RPM?
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mustangboy
Gearhead Posts: 652
From: Ont, Canada
Registered: Mar 2002
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posted 10-03-2002 11:19 PM
Ok got the father/son thing figured out. ------------------
1968 mustang j-code sprint.13.69@101 1963Falcon waiting for a rebirth.
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65_302
Gearhead Posts: 239
From: Bixby, OK
Registered: Jul 2001
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posted 10-04-2002 08:15 AM
No 60 ft speed. Shift point is 5600.
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mustangzrule
Journeyman Posts: 87
From: Orion, MI
Registered: Sep 2002
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posted 10-04-2002 09:51 AM
Shift at 42 and 71 with the C4 and 4.11 diff @ 5600RPM. Max speed would be 105.Assuming your Tremec is geared 3.27,1.99,1.34,1,.68:
Shift at 32, 52.5, 78, and 105 MPH with the Tremec and 4.11 diff @ 5600RPM. Max speed would be 154. You might lose top speed with the C4. If you increase your gear from a 411 to a 430, your top speed would be reduced to 100MPH and with a 4.50 you would max out at 95. Fascinating tradeoff. Top speed for ET. I'd love to know how this affects your ET.
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65_289
Gearhead Posts: 761
From:
Registered: Jul 2001
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posted 10-04-2002 12:23 PM
quote:
Originally posted by 65_302:
No 60 ft speed. Shift point is 5600.
5900. And mustangzrule, I can't shift at a particular mph, since my speedo is "off". 
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65_302
Gearhead Posts: 239
From: Bixby, OK
Registered: Jul 2001
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posted 10-04-2002 01:05 PM
Thar U go again, changing things on me between the pit and the line Anyway, it will have to wait until next weekend. We have got to find the lost .12 sec of 60 ft time.
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