PONTIAC ZONE TECH FORUMS
 

Go Back   PONTIAC ZONE TECH FORUMS >
Engine Tech
> Grape Vine - General Discussion
User Name
Password

Grape Vine - General Discussion Shop Talk - Bench Racing, No political or religious topics are allowed.

sponser links

Reply
 
Thread Tools
Old 12-17-18, 11:43AM   #1
72lemans400
Whipersnapper
 
72lemans400's Avatar
 
Join Date: Nov 2005
Location: chesapeake, va
Posts: 74
Default Gear Vendor or Ford 9 Inch??

Guys,

Got a good problem to solve... what to do next to my 72 Lemans.

Ive got a fairly mild 455 (9.5 CR with big valve factory heads and a mild cam) in it backed up with a TH350 and a 10 bolt out back with open diff and highway gears. Has 275 drag radials as well.

Mostly a fun street car that I want to take on a few trips this year.

so.... Gear Vendors or a Ford 9 Inch with 3.25 and track-loc? Ill wind up doing both, but which one should I go with first?
72lemans400 is offline   Reply With Quote
Old 12-17-18, 02:22PM   #2
Gach
Administrator
 
Gach's Avatar
 
Join Date: May 2003
Location: ....
Posts: 18,676
Default

I’d do to Ford 9”. 10 bolt is a weak rear. With 3.25 gear you’ll had no problem cruising.
__________________
The things they hide, the way they spin things, the excuses that they make and the things they omit.
Gach is offline   Reply With Quote
Old 12-17-18, 07:50PM   #3
JSPONT
Registered User
 
JSPONT's Avatar
 
Join Date: Feb 2014
Posts: 1,414
Default

rear 1st but you have to consider gear ration now. 3.25 with od you need a motor to make power at 1200 rpm or it will be a bucking bronco in OD
JSPONT is offline   Reply With Quote
Old 12-17-18, 08:33PM   #4
Hooter
Goatroper
 
Hooter's Avatar
 
Join Date: Dec 2007
Location: Springfield, IL
Posts: 268
Default

In my 65, I have a 3.70 gear in a 9” with a gear vendors. The 3.25 will be pretty high after you add the OD.
__________________
63 Lemans Drag Car - Endless money pit.....(SOLD)

65 Lemans - 521, T400, 3.70 gear, 3770 lbs. Street car.
Hooter is offline   Reply With Quote
Old 12-18-18, 10:32AM   #5
sprint250
Moteesuh
 
sprint250's Avatar
 
Join Date: Jul 2002
Location: La Jolla , California
Posts: 3,576
Default

Figure what the rear end ratio is gonna be in final drive with the GV OD & that'll give you your cruise RPM/MPH (GV can help you with that). With a 3.23/3.25 ratio in OD it may be in a low to mid 2 series .Remember std economy rear axle ratio for a lot of cars was 2.73.
In the late '70s and into the '80s the manufacturers were even putting 2.23 rear gears in 'em .The Pontiac V8 engine will be somewhat forgiving with the broad torque curve they are notorious for.

With the OD you can get away with a deeper gear on the street + split gears that's the advantage.
So unless you have the 160mph or faster speedo & plan on going to UTAH and running on the salt for top speed.........?

But put the niner in there first. Those are EZIER to change ratios on.
__________________
Step Away From The KOOL AID !
sprint250 is offline   Reply With Quote
Old 12-20-18, 10:43AM   #6
72lemans400
Whipersnapper
 
72lemans400's Avatar
 
Join Date: Nov 2005
Location: chesapeake, va
Posts: 74
Default

Thanks for the input. Hoping to get enough cash to get both in by the april rod run in Pigeon Forge. about a 5 hours cruise from here. Not sure I want to be running at 70 for that long in anything taller than a 3.25 without some sort of OD.


Anyone ever had experience with the Quick performance 9" packages?
72lemans400 is offline   Reply With Quote
Old 12-20-18, 02:43PM   #7
Hooter
Goatroper
 
Hooter's Avatar
 
Join Date: Dec 2007
Location: Springfield, IL
Posts: 268
Default

Quote:
Originally Posted by 72lemans400 View Post
Thanks for the input. Hoping to get enough cash to get both in by the april rod run in Pigeon Forge. about a 5 hours cruise from here. Not sure I want to be running at 70 for that long in anything taller than a 3.25 without some sort of OD.


Anyone ever had experience with the Quick performance 9" packages?
That’s the same 9” I run. Also bought Wilwoods from them.
__________________
63 Lemans Drag Car - Endless money pit.....(SOLD)

65 Lemans - 521, T400, 3.70 gear, 3770 lbs. Street car.
Hooter is offline   Reply With Quote
Old 12-21-18, 02:27AM   #8
Gach
Administrator
 
Gach's Avatar
 
Join Date: May 2003
Location: ....
Posts: 18,676
Default

Plus their much heavier. Maybe that’s why they take 12 hp more.
__________________
The things they hide, the way they spin things, the excuses that they make and the things they omit.
Gach is offline   Reply With Quote
Old 12-21-18, 09:28AM   #9
JSPONT
Registered User
 
JSPONT's Avatar
 
Join Date: Feb 2014
Posts: 1,414
Default

I think it has to do with the offset pinion. I do not think it is 12 hp. I have an article from one of the magazines, does a full comparison of the 12 bolt, 9 inch, and dana60. Has there weight loaded and all. If my memory recalls is was way less than 12. Once you start making high H.P. the 12 bolt is the last one you should choose. Look under all the real fast cars, what do you see.
JSPONT is offline   Reply With Quote
Old 12-21-18, 11:04AM   #10
Mb125
Registered User
 
Mb125's Avatar
 
Join Date: Mar 2005
Location: AZ
Posts: 4,084
Default

The shortfall for a 12 bolt is the limitations in the axle diameter because of the smaller inside diameter of the differential bearings.
Plenty 12 bolts in 8 second cars.
The real fast cars are using a 10 inch ring gear inside the 9 inch housings and 40 spline axles.
__________________
You can shear a sheep many times, but you can only skin them once.
Mb125 is offline   Reply With Quote
Old 12-22-18, 12:19AM   #11
sprint250
Moteesuh
 
sprint250's Avatar
 
Join Date: Jul 2002
Location: La Jolla , California
Posts: 3,576
Default

The venerable BOP 9.3 from the good old days '57 thru '64 was the CHIT but it disappeared when GM quit producing it and all the good cores got scrapped.
They were putin' 'em in everything form gassers to fuel dragsters.
Fabcraft in Texas offers parts for them.
Summers Brothers used to make axles for them.

All the pro-mod on up cars are using STRANGE ,Mark Williams or = housings & components
__________________
Step Away From The KOOL AID !
sprint250 is offline   Reply With Quote
Old 12-22-18, 01:18AM   #12
Gach
Administrator
 
Gach's Avatar
 
Join Date: May 2003
Location: ....
Posts: 18,676
Default

Quote:
Originally Posted by Mb125 View Post
The shortfall for a 12 bolt is the limitations in the axle diameter because of the smaller inside diameter of the differential bearings.
Plenty 12 bolts in 8 second cars.
The real fast cars are using a 10 inch ring gear inside the 9 inch housings and 40 spline axles.
Yup, my buddy with Camaro runs 8.20’s with 12 bolt. Welded Chrome Molly axle tube..axle tube braces, and after market rear end cover. Have same 12 bolt rear set up, it was in the car when I bought it. With Mark Williams axels... spool with Pro Gears.

But I agree if your making 1000-1200 hp the inside bearing diameter is weak link.

It’s probably cheaper to buy Ford 9” all made up to fit your car then to build a 12 bolt like mine.

But I’m wouldn’t be afraid to run my set up making 800 plus HP
__________________
The things they hide, the way they spin things, the excuses that they make and the things they omit.
Gach is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Switching to 3.23 from 3.55 gear on Pontiac 10 bolt 8.2 inch gear vicgto Suspension - Brakes - Tires 1 02-22-12 11:49PM
"Ideal" Gear Ratios? Paul Cramm Transmission TECH 16 03-26-11 07:58PM
effective gear ratio vs. equivalent ratio?? jeffb Suspension - Brakes - Tires 0 01-05-11 11:57AM
Low Oil Pressure At Idle In Gear LFSADRG Engine Tech Discussion - Street or Strip 14 07-10-08 03:03PM
2.20 First gear admin Transmission TECH 1 04-08-03 09:59PM


All times are GMT -3. The time now is 08:57AM.

Featured Ads
Ken's Speed & Machine
Mayhem Turbocharging

Carter Cryogenics.  What can we freeze for you?

Pacific Performance Racing

Central Virginia Machine Service.  Home of the Injun Engine!

All Pontiac Engine Kits

Larry's Auto Machine.  Full serivce auto, marine machine shop, domestic and foreign.

Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
2001 - 2007 PontiacZone.com
Page generated in 0.08910 seconds with 38 queries