4.11 F**d 9 In. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chevjayfsd · 11-13-2002, 09:42 PM

How much do you think a 4.11 geared 9 inch posi would be, and how hard is it to put this into my 72??
and if my truck runs 14 flat right now how much would it improve my times

jmanz69 · 11-13-2002, 10:01 PM

I don't know about cost, but it would take a little work to get it in there. Not hard though, some of the vendors have kits for this, I believe ECE makes a kit. 4.11 would make your times a little better, but it really depends on your engine, if it can handle the extra RPM it will get earlier with the lower ratio, and the traction you have. The Ford 9" is good but you don't really need it if you aren't going to have huge HP. Your 12 bolt will take a lot of abuse. If you already have posi, and just change gears, it would cost about $200 or so to have them set up. Of course the cost of gears too. If you have an open diff, then it will be more. Maybe see if you can find a different rearend out of one of our trucks. Would be an easier swap. I have thought about going with a 9", but changed my mind since my engine isn't going to be wild.

Good luck in whatever you decide.

Jason

crazy longhorn · 11-13-2002, 10:16 PM

Did you know that because the pinion is lower on a 9 " Ford(yea i said the bad word), it takes more power to turn it than the 12 bolt chevy? Im runnin Richmond 4.10s in the 12 bolt thats under my longhorn......it will take all the guff that the 383 will give it. Its a fast gear tho, that 383 has seen 7200 in low a couple times , just because the 4.10s wind it that quick! (yea the old man is gettin slow).........

bigjimzlll · 11-13-2002, 10:23 PM

longhorns right...they do use more power...the dodge 83/4 is better yet....

mikep · 11-13-2002, 10:36 PM

Lets talk cost effectiveness ...

I dont know how handy you are with welders and stuff like that but you can get a Dana 60 with 4.10 gears and a posi or locker setup for usually under a hundred bucks. At least thats what I paid for the last 3 Iv'e bought including the donor of the detroit locker unit in my current truck. You can get semifloater axles made up for about $400 and then its just a question of welding new housing ends on the dana tubes and reusing all your brake components. That way you end up with a dana 60 with practically bulletproof axles in the bolt pattern of your choice . Total expenditure under $600.

Thats not bad if you consider what a good 31 spline Ford 9 inch rear end setup will cost you especially after you factor in the cost of having the bolt pattern changed. Ford wasnt very generous with posi carriers in their trucks or cars for that matter either so theyre hard to find in good ratios and with the good strong parts. 28 splined carriers are more common but theyr'e somewhat anemic. Last set up 9 inch 4.11 geared 31 spline TracLoc carrier assy I bought I paid over $500 and that I considered a bargain at the time. That was just the center section. I sold the 4.56 geared 31 spline Detroit Locker carrier that was in that car when I got it for $900. See where I'm going with this. And those werent even Nodular or double ribbed case carriers. Everybody wants the 9 inch so supply and demand is in effect big time. The Dana 60 will be as strong or stronger and cost a lot less.

Truckstr · 11-13-2002, 10:42 PM

longhorn is very right. Your sig says that you have a 355ci engine with turbo 350 auto trans, right? Then to tell you whether or not the 4.11 would help or hurt in the quarter, one would have to know the cam, carb, headers or not, weight, tire size, etc. (see where I'm going with this?). Then that info can be loaded into DD2000 and Drag 2000 to compute what kind of times you should turn.

I built a virtual '67 Chevy truck in Drag 2000 with 383 engine and 700R4 trans. I actually had better times with a 3.54 gear than with a 4.11 - but that was with the engine combo that I had loaded in. It all depends on the combo.

Cars (and trucks) should be built as a "system" to allow all of the parts to work together. The combo that works for me, may not work for somebody else. It all depends on what one is looking for at the outset.

Post somemore details and I'll be glad to load 'em into DD2000 for ya.

chevjayfsd · 11-13-2002, 11:06 PM

I have the engine uploaded into DD2000, but how do you setup the gears??? i dont see where to do this...

Project1970 · 11-13-2002, 11:28 PM

Gear setup requires Drag2000 - aka Desktop Dragstrip. It's a separate program, but IIRC it can take Desktop Dyno files and use those for the power curve. You also give it things like weight, vehicle measurements, stuff like that (not 100% certain since I've never used Desktop Dragstrip in particular)...

Truckstr · 11-13-2002, 11:33 PM

Project 1970 is correct, you will need Drag 2000. Shoot me PM and attach the DD2000 file and I can do it for ya. I'll use the data that I have set up for my '67 - it should be close. If you are sticking with the turbo 350, then the variable is the weight and distribution of the weight along with the tire size.

11-13-2002, 09:42 PM	#1
chevjayfsd Project 7dos Join Date: Aug 2001 Location: Abilene, Texas Posts: 876	4.11 Fd 9 In. How much do you think a 4.11 geared 9 inch posi would be, and how hard is it to put this into my 72?? and if my truck runs 14 flat right now how much would it improve my times __________________ 7DOS - 1972 C-10** 350/350 Porterbuilt/Accuair 20x8.5/20x10 Ride Low or Die PSSST - Yes it's bagged. 7dos build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=610290

11-13-2002, 10:16 PM	#3
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	Did you know that because the pinion is lower on a 9 " Ford(yea i said the bad word), it takes more power to turn it than the 12 bolt chevy? Im runnin Richmond 4.10s in the 12 bolt thats under my longhorn......it will take all the guff that the 383 will give it. Its a fast gear tho, that 383 has seen 7200 in low a couple times , just because the 4.10s wind it that quick! (yea the old man is gettin slow)......... __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

11-13-2002, 10:23 PM	#4
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	longhorns right...they do use more power...the dodge 83/4 is better yet.... __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

11-13-2002, 10:36 PM	#5
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	Lets talk cost effectiveness ... I dont know how handy you are with welders and stuff like that but you can get a Dana 60 with 4.10 gears and a posi or locker setup for usually under a hundred bucks. At least thats what I paid for the last 3 Iv'e bought including the donor of the detroit locker unit in my current truck. You can get semifloater axles made up for about $400 and then its just a question of welding new housing ends on the dana tubes and reusing all your brake components. That way you end up with a dana 60 with practically bulletproof axles in the bolt pattern of your choice . Total expenditure under $600. Thats not bad if you consider what a good 31 spline Ford 9 inch rear end setup will cost you especially after you factor in the cost of having the bolt pattern changed. Ford wasnt very generous with posi carriers in their trucks or cars for that matter either so theyre hard to find in good ratios and with the good strong parts. 28 splined carriers are more common but theyr'e somewhat anemic. Last set up 9 inch 4.11 geared 31 spline TracLoc carrier assy I bought I paid over $500 and that I considered a bargain at the time. That was just the center section. I sold the 4.56 geared 31 spline Detroit Locker carrier that was in that car when I got it for $900. See where I'm going with this. And those werent even Nodular or double ribbed case carriers. Everybody wants the 9 inch so supply and demand is in effect big time. The Dana 60 will be as strong or stronger and cost a lot less. __________________ No truck :-( Last edited by mikep; 11-13-2002 at 10:39 PM.

11-13-2002, 10:42 PM	#6
Truckstr Registered User Join Date: Nov 2002 Location: Lebanon, Tennessee Posts: 1,372	longhorn is very right. Your sig says that you have a 355ci engine with turbo 350 auto trans, right? Then to tell you whether or not the 4.11 would help or hurt in the quarter, one would have to know the cam, carb, headers or not, weight, tire size, etc. (see where I'm going with this?). Then that info can be loaded into DD2000 and Drag 2000 to compute what kind of times you should turn. I built a virtual '67 Chevy truck in Drag 2000 with 383 engine and 700R4 trans. I actually had better times with a 3.54 gear than with a 4.11 - but that was with the engine combo that I had loaded in. It all depends on the combo. Cars (and trucks) should be built as a "system" to allow all of the parts to work together. The combo that works for me, may not work for somebody else. It all depends on what one is looking for at the outset. Post somemore details and I'll be glad to load 'em into DD2000 for ya. __________________ Jeff '67 short Fleet; my ongoing project. '66 long Fleet; my original "baby." Live life or bust trying. Last edited by Truckstr; 11-13-2002 at 11:34 PM.

11-13-2002, 10:01 PM	#2
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	I don't know about cost, but it would take a little work to get it in there. Not hard though, some of the vendors have kits for this, I believe ECE makes a kit. 4.11 would make your times a little better, but it really depends on your engine, if it can handle the extra RPM it will get earlier with the lower ratio, and the traction you have. The Ford 9" is good but you don't really need it if you aren't going to have huge HP. Your 12 bolt will take a lot of abuse. If you already have posi, and just change gears, it would cost about $200 or so to have them set up. Of course the cost of gears too. If you have an open diff, then it will be more. Maybe see if you can find a different rearend out of one of our trucks. Would be an easier swap. I have thought about going with a 9", but changed my mind since my engine isn't going to be wild. Good luck in whatever you decide. Jason

11-13-2002, 11:06 PM	#7
chevjayfsd Project 7dos Join Date: Aug 2001 Location: Abilene, Texas Posts: 876	I have the engine uploaded into DD2000, but how do you setup the gears??? i dont see where to do this... __________________ 7DOS - 1972 C-10 350/350 Porterbuilt/Accuair 20x8.5/20x10 Ride Low or Die PSSST - Yes it's bagged. 7dos build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=610290

11-13-2002, 11:28 PM	#8
Project1970 14.1 @ 96MPH Join Date: Jul 2001 Location: Mesa, AZ Posts: 2,811	Gear setup requires Drag2000 - aka Desktop Dragstrip. It's a separate program, but IIRC it can take Desktop Dyno files and use those for the power curve. You also give it things like weight, vehicle measurements, stuff like that (not 100% certain since I've never used Desktop Dragstrip in particular)... __________________ Project1970 - LS1 Swap Complete!

11-13-2002, 11:33 PM	#9
Truckstr Registered User Join Date: Nov 2002 Location: Lebanon, Tennessee Posts: 1,372	Project 1970 is correct, you will need Drag 2000. Shoot me PM and attach the DD2000 file and I can do it for ya. I'll use the data that I have set up for my '67 - it should be close. If you are sticking with the turbo 350, then the variable is the weight and distribution of the weight along with the tire size. __________________ Jeff '67 short Fleet; my ongoing project. '66 long Fleet; my original "baby." Live life or bust trying.



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