IsItDoneYet?
Senior Member
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 09-26-07 07:03 AM - Post#1261770
I know we have covered this before but I am going to bring it up again.
Have to rebuild my 9" after it spat the pinion out last week so now looking at what gears I should instal.
Car has a 470hp 550lbft big block backed up with a DNE 4 + 1, first gear is 3.27-1 running 29" tyres. All installed in a 56 Chevy.
Was running 3.50 but looking at either a 3.25 or a 3.73. I know if I do the maths it will give me an indication of which gear but that is no substitute for real world referance points.
Over the 1/8th car runs somewhere between 7-8seconds at around 85-90mph.
Thing is the car seems slow to me. It is fine from a standstill or rolling start but when I punch it on the motorway I am missing the big push in the back.
With petrol nearing $10 a gallon I am looking for the same thing everybody else is. 11 second 1/4's with necksnapping acceleration, the drinking habit of a Camel and a crusing speed in the 80's at 1700rpm...
Maybe 3.50's are that compromise but I can't help thinking that with all the torque at my disposal making the engine work harder withthe 3.25 might actually give me what I want. Or is it the 3.73.... Choices, choices.
In closing, I have used the calculators but would like to hear from others that have actually real world experiance of using differant gears and are they happy with their choice.
P. 
56 Bel Air Sedan, aka The Pumpkin. 28 Years and nearly done!
56 Chevy 3100 Big Window Stepside,aka The Pumpkin Patch Speed Shop! Moving under its own power at last... |
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 MikeB
"7th Year" Silver Supporting Member
Posts: 7493
Loc: Plano, TX
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09-26-07 08:11 AM - Post#1261798
In response to IsItDoneYet?
Assuming a 1:1 top gear, I would go with 3.00 rear gears. That should work well with all your engine's torque and the very low 1st gear, as well as giving you a reasonable RPM at cruising speeds.
Just for comparison purposes, my old 350, which had maybe 350 lb/ft TQ, was happy with a 2.52 low gear and 3.42 axle. Let's see, that equates to 8.6:1 reduction.
With your 3.27 low gear and a 3.0 axle, you'd have 9.8:1 overall reduction AND 57% more TQ than my 350. Heck, your engine/trans would probably work fine with an axle ratio in the high-2s. The RPMs would drop more between shifts, so quarter mile times might increase, depending on how flat your TQ curve is.
Real Hot Rods have a Clutch!
1955 210 sedan, solid lifter 327, Brodix IK180 heads, Muncie M20, Wilwood front brakes
1969 C-10 LWB pickup
My car pictures
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Tri5man
Contributor
Posts: 494
Loc: Anchorage, Kentucky
Reg: 06-26-07
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09-26-07 08:23 AM - Post#1261810
In response to MikeB
I'm not too familar with all the mathmatic calculations but after many years of Streetrods with high rear ends and overdrive transmissions, I sure do like the way my 56 Bel Air pulls with a 350, 4 speed. The only draw back is on the highway at 65 its turning close to 3000 rpm. I'm not sure what rear end it has. I believe it's the original which came with the 6 cylinder 3 speed. What rear do you think it has? Remember the "Old Day's" when you wanted a 4:11 or better yet a 4:56. But then again you never drove 4 hours or better to attend a car show.
56 Bel Air 2 door post, 350/4 speed
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MikeB
"7th Year" Silver Supporting Member
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09-26-07 08:34 AM - Post#1261814
In response to Tri5man
I believe it's the original which came with the 6 cylinder 3 speed. What rear do you think it has?
I think a 6cyl 3-speed had 3.70 gears and a 265 w/ 3-speed had 3.55. But I've been wrong before! 
Remember the "Old Day's" when you wanted a 4:11 or better yet a 4:56.
Been there, done that. Had a 57 with a 292 (+.060" 283), wide ratio Muncie and 4.56 open diff.
The biggest challenge was putting the power to the pavement in low gear, but some used 8.25 tires off my Dad's Olds helped a lot. The car surely did embarass a few 396 Chevelle owners, at least in a 1-2 block street race.
Cruising from my house to the drive-in was painful even at 60 mph. No way could I have gone on even a 50 mile cruise. 
In retrospect, 4.11s would have been a lot better.
Real Hot Rods have a Clutch!
1955 210 sedan, solid lifter 327, Brodix IK180 heads, Muncie M20, Wilwood front brakes
1969 C-10 LWB pickup
My car pictures
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 No_Dice
"9th Year" Silver Supporting Member
Posts: 13557
Loc: San Jose, CA
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09-26-07 08:45 AM - Post#1261821
In response to MikeB
11 second quarters and 1700 RPMs at 80MPH? Two different cars. You have one foot in a race car and one foot in a street car. I have similar numbers in my car with respect to HP, tire height, 6 speed, etc and my 3.0 gear is perfect for my driving style - street only. If I were to go to a deeper gear it would be a 3.7 and I would assume that I would change it from time to time.
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55chevy383
Senior Member
Posts: 1018
Age: 42
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09-26-07 08:49 AM - Post#1261826
In response to No_Dice
3.73's should give you the grunt you're looking for at the track and with an overdrive shouldn't be to harsh at freeway speeds.
Phil
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1957_BelAir
Junior Contributor
Posts: 737
Loc: San Marcos, Texas
Reg: 11-26-02
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09-26-07 09:25 AM - Post#1261860
In response to 55chevy383
I have a similar 57 with a BB, Jerico 4 speed and a gear vendors overdrive. I run a 3:89 and with the OD it is OK on the highway, though it still turns some RPM. Without the OD it is too steep and you have to cruise down at about 60.
Performance wise, it cooks in first and second, but actually could use more gear in third and forth. I wouldn't go to a lower numerically ratio unless you are ready to give up some performance to get the better economy, or want to downshift a lot.
Good luck,
Jay
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MikeB
"7th Year" Silver Supporting Member
Posts: 7493
Loc: Plano, TX
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09-26-07 09:30 AM - Post#1261863
In response to 55chevy383
I thought that DNE trans had a 1:1 5th gear. 
Real Hot Rods have a Clutch!
1955 210 sedan, solid lifter 327, Brodix IK180 heads, Muncie M20, Wilwood front brakes
1969 C-10 LWB pickup
My car pictures
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Edited by MikeB on 09-26-07 09:30 AM. Reason for edit: No reason given.
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raycow
Ultra Senior Member
Posts: 13841
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09-26-07 11:30 AM - Post#1261930
In response to MikeB
I think a 6cyl 3-speed had 3.70 gears and a 265 w/ 3-speed had 3.55.
A 55 or 56 3-speed would have had a 3.70 rear with either engine. In 57 this changed to 3.55, probably because of the smaller OD of the 14" tires.
Ray
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Limey Tri Chevy
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09-26-07 11:42 AM - Post#1261939
In response to raycow
tire height x rpm x 0.002975 divided by rear end ratio = speed.
Paul play with it mate. My 4 speed auto wagon will have a 3.70 posi gear I have sitting here. The F150 H/D lightning also has a 3.73 gear which is fantastic on both punch and legs. Aim to have about 23mph per 1000 rpm and you should be in the 'zone' on both counts.
'57 Bel Air 4dr wagon
'57 210 2dr
'55 Bel Air 2dr
'02 H/D Lightning
'08 Anniversary Custom 1200 Sportster
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IsItDoneYet?
Senior Member
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09-26-07 03:04 PM - Post#1262066
In response to No_Dice
11 second quarters and 1700 RPMs at 80MPH? Two different cars. You have one foot in a race car and one foot in a street car. I have similar numbers in my car with respect to HP, tire height, 6 speed, etc and my 3.0 gear is perfect for my driving style - street only. If I were to go to a deeper gear it would be a 3.7 and I would assume that I would change it from time to time.
Ah Mr Dice....
As I said I want my cake, to eat it AND get change from a £1......
We have had this discussion before, think teh only way to get it settled is to jump on a plane and test drive the DiceMobile
Promise I won't break it any worse than I break my own..................................
P.
56 Bel Air Sedan, aka The Pumpkin. 28 Years and nearly done!
56 Chevy 3100 Big Window Stepside,aka The Pumpkin Patch Speed Shop! Moving under its own power at last... |
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Limey Tri Chevy
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09-26-07 03:07 PM - Post#1262069
In response to IsItDoneYet?
[quote from Paul the pumpkin pulveriser!!]
"Promise I won't break it any worse than I break my own.................................."
So that would leave No Dice with a few winter projects then eh 
'57 Bel Air 4dr wagon
'57 210 2dr
'55 Bel Air 2dr
'02 H/D Lightning
'08 Anniversary Custom 1200 Sportster
'07 Fat Boy
'30 Model A sedan
My pics
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IsItDoneYet?
Senior Member
Posts: 1084
Age: 46
Loc: Covered in Oil N' Burnt R...
Reg: 12-14-05
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09-26-07 03:08 PM - Post#1262071
In response to Limey Tri Chevy
Adam,
Lee's gears ended up being 3.89 which was just too high. Looks like I am going to get an after market case and pinion support, use a set of 3.25 gears and the locker I already have.
Using your maths 3K would give me 80mph. Hell if it is too slow I will just have to bolt on the injectors that are sitting in the shed!
P.
56 Bel Air Sedan, aka The Pumpkin. 28 Years and nearly done!
56 Chevy 3100 Big Window Stepside,aka The Pumpkin Patch Speed Shop! Moving under its own power at last... |
|
No_Dice
"9th Year" Silver Supporting Member
Posts: 13557
Loc: San Jose, CA
Reg: 04-23-01
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09-26-07 03:14 PM - Post#1262078
In response to IsItDoneYet?
think teh only way to get it settled is to jump on a plane and test drive the DiceMobile
Promise I won't break it any worse than I break my own..................................
P.
Quick...smellin salts...open a window....he is hallucinating and speaking in tongues.
 You are welcome anytime to be a PASSENGER in my car.
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Limey Tri Chevy
"5th Year" Silver Supporting Member
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09-26-07 03:50 PM - Post#1262107
In response to No_Dice
Paul, just make sure your main cruising speed (100mph+ for you!!) is around your peak torque rpm. That will give you the best mpg, the 476 cubic inches will take care of the G's.
Spoke to Russ and he can 'assist' you in your search when he is over there next week.
'57 Bel Air 4dr wagon
'57 210 2dr
'55 Bel Air 2dr
'02 H/D Lightning
'08 Anniversary Custom 1200 Sportster
'07 Fat Boy
'30 Model A sedan
My pics
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IsItDoneYet?
Senior Member
Posts: 1084
Age: 46
Loc: Covered in Oil N' Burnt R...
Reg: 12-14-05
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09-27-07 01:45 AM - Post#1262379
In response to Limey Tri Chevy
Adam,
Using your calculator.....
My crusing speed would be 106.1mph with the 3.25, so spot on in terms of where I want to be
Mind you top speed is a bit off at 153....
Will give you a call over the weekend with regards to Russ.
P.
56 Bel Air Sedan, aka The Pumpkin. 28 Years and nearly done!
56 Chevy 3100 Big Window Stepside,aka The Pumpkin Patch Speed Shop! Moving under its own power at last... |
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 rj_ly
"4th Year" Gold Supporting Member & Tri-5 Calendar Creator
Posts: 16335
Loc: Southwestern OH
Reg: 11-15-02
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09-27-07 10:12 AM - Post#1262613
In response to IsItDoneYet?
Most of my '57s have 3:55 gears in the rear.
At 70mph the car tachs about 2800rpms or close.
An overdrive to get the rpms lower would be great. If I could afford one.
57 Hrdtp(mine for 38 years July 10)
57 210 4-dr Sdn(35 yrs Aug 10)
57 Hrdtp(30 yrs Jan 10)
57 windowed S. Delivery(28 yrs Oct 09)
57 150 Wgn(22 yrs Mar 10)
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IsItDoneYet?
Senior Member
Posts: 1084
Age: 46
Loc: Covered in Oil N' Burnt R...
Reg: 12-14-05
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09-27-07 02:21 PM - Post#1262772
In response to rj_ly
RJ,
3K was giving me a shade over 70 with my 3.50's
I can loose 400rpm with the 3.25 for the same speed.
Looks like my mind has been made up, that and the fact I have a set of 3.25 gears already......
Maybe I will ask Santa if he will bring me a gearvendors overdrive for Christmas...
P.
56 Bel Air Sedan, aka The Pumpkin. 28 Years and nearly done!
56 Chevy 3100 Big Window Stepside,aka The Pumpkin Patch Speed Shop! Moving under its own power at last... |
Edited by IsItDoneYet? on 09-27-07 02:21 PM. Reason for edit: No reason given.
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rj_ly
"4th Year" Gold Supporting Member & Tri-5 Calendar Creator
Posts: 16335
Loc: Southwestern OH
Reg: 11-15-02
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09-28-07 09:47 AM - Post#1263405
In response to IsItDoneYet?
If I could locate a 5-speed I could afford I would probably go to a higher rear gear set.
57 Hrdtp(mine for 38 years July 10)
57 210 4-dr Sdn(35 yrs Aug 10)
57 Hrdtp(30 yrs Jan 10)
57 windowed S. Delivery(28 yrs Oct 09)
57 150 Wgn(22 yrs Mar 10)
57 210 2-dr Sdn(5 yrs Oct O9) |
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Alex Ross (4)
