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Username Post: rear end ratios        (Topic#142188)
mlrailguy 
Senior Member
Posts: 427

Loc: Moses Lake,WA USA
Reg: 12-30-02
10-13-06 12:23 PM - Post#1017528    

I am nearing completion of my 67 Camaro. The rear seems sloppy to me by grabbing the pinion and twisting by hand. Lots of clunking. Any way, I have changed to 335 hp 327 and close ratio M21, and wondering what would be a good gear choice for all around driving and maybe some Saturday night racing?



 




artak 
Valued Contributor
Posts: 4008
artak
Reg: 05-22-05
Re: rear end ratios
10-13-06 12:30 PM - Post#1017529    
    In response to mlrailguy

The gear has to match up with your power band. What does the engine's power curve look like?

Casting Numbers


 
1FATGMC 
Senior Member
Posts: 336
1FATGMC
Loc: Southeast Utah
Reg: 04-29-04
Re: rear end ratios
10-13-06 12:40 PM - Post#1017530    
    In response to mlrailguy

Quote:

I am nearing completion of my 67 Camaro. The rear seems sloppy to me by grabbing the pinion and twisting by hand. Lots of clunking. Any way, I have changed to 335 hp 327 and close ratio M21, and wondering what would be a good gear choice for all around driving and maybe some Saturday night racing?




I just put up spreadsheets on my site that can help you (HERE ).

Download the 4 speed car one. Then input the 1st, 2nd, 3rd, and 4th gear ratios (2.20, 1.64, 1.28, 1.00 for your transmission). Next input your tire size. Then you can input different rear gear ratios and see the rpm in each gear and also the rpm drop when you shift from one gear to the next.

Using this you can try and choose a rear gear that will work best for your driving requirements and the torque/hp range of your motor.

c ya,

Sum

1FATGMC Lakester Construction


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17111
grumpyvette
Age: 69
Loc: FLORIDA USA
Reg: 03-16-01
Re: rear end ratios
10-13-06 01:45 PM - Post#1017531    
    In response to 1FATGMC

FIRST, THANK YOU IFATGMC!!!
THATS VERY USEFUL, IF YOU DON,T MIND ILL MAKE THIS A STICKY

http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html

HERES OTHER INFO LINKS

http://www.wallaceracing.com/reargear.htm

http://users.erols.com/srweiss/calcmph.htm

http://users.erols.com/srweiss/calcrpm.htm

http://users.erols.com/srweiss/calcrgr.htm

http://users.erols.com/srweiss/transc.htm#tabtop

http://users.erols.com/srweiss/transc.htm#Auto



 
MikeB 
Ultra Senior Member
Posts: 10058
MikeB
Loc: Plano, TX
Reg: 08-28-03
Re: rear end ratios
10-14-06 10:58 AM - Post#1017532    
    In response to mlrailguy

If you rotate the pinion shaft and it clunks, that's not necessarily bad. My pickup's 12-bolt has done that since I bought it in 1989. However, you should not be able to move it up and down or from side to side.

It's a fairly simple task to remove the cover and check ring/pinion backlash using a dial indicator and magnetic base. That will also give you the opportunity to visually inspect all the gears.

I can tell you that a 327 w/ close ratio Muncie will like a 3.70 axle ratio. First gear in that trans is VERY tall. In fact, first gear in my M20 is a bit tall even with a 3.42 axle.


1982 C10 SWB pickup: Unmolested base truck, original paint. Originally had 250 six and 3-on-the-tree
Now has 355 with Vortec heads, RamJet roller cam, LS6 beehive springs, TH350
Retired, but working part-time on 50s-70s cars & trucks.


 
mlrailguy 
Senior Member
Posts: 427

Loc: Moses Lake,WA USA
Reg: 12-30-02
Re: rear end ratios
10-14-06 03:39 PM - Post#1017533    
    In response to MikeB

I think this was clunking more than it should. Took cover off and all looks great. 2.56 so think I will go with some 3.08's I got for good price.

Just DUNE it


 
MikeB 
Ultra Senior Member
Posts: 10058
MikeB
Loc: Plano, TX
Reg: 08-28-03
Re: rear end ratios
10-16-06 05:41 AM - Post#1017534    
    In response to mlrailguy

Plan on replacing the pinion bearings and races. (The rear race is not much fun to install unless you have a perfectly sized driver.) If you're lucky, you'll be able to use the original pinion shim(s) and crush sleeve.

If you plan to do it yourself, here are some decent instructions: http://www.ringpinion.com/downloads/yukoninstman.pdf


1982 C10 SWB pickup: Unmolested base truck, original paint. Originally had 250 six and 3-on-the-tree
Now has 355 with Vortec heads, RamJet roller cam, LS6 beehive springs, TH350
Retired, but working part-time on 50s-70s cars & trucks.


 
coolvelle 
Senior Member
Posts: 54
coolvelle
Loc: Colorado
Reg: 09-08-06
Re: rear end ratios
10-16-06 03:21 PM - Post#1017535    
    In response to MikeB

I may be wrong here, but I thought you could not swap ring and pinion form a 2 ratio to a 3 ratio without a new carrier.

1972 chevelle 383 stroker/ 425hp, holley750 4150, Th350 3000 stall 3:90 gears MSD all the way! Living a childhood dream! http://www.picturetrail.com/uid6740038


 
jb2wheeler 
Valued Contributor
Posts: 4340

Loc: Louisville KY
Reg: 05-09-04
Re: rear end ratios
10-18-06 11:04 AM - Post#1017536    
    In response to coolvelle

Coolvelle, I may be wrong here, but if we are discussing the 10 bolt, 8.5 rear, then I am under the impression that if you already have a 2.73 or lower ratio (numerically higher) that they interchange, but the smaller carrier, 2.41, will not take the larger gears. Anybody concur? JB



 
MikeB 
Ultra Senior Member
Posts: 10058
MikeB
Loc: Plano, TX
Reg: 08-28-03
Re: rear end ratios
10-21-06 02:12 AM - Post#1017537    
    In response to jb2wheeler

Quote:

...if we are discussing the 10 bolt, 8.5 rear, then I am under the impression that if you already have a 2.73 or lower ratio (numerically higher) that they interchange, but the smaller carrier, 2.41, will not take the larger gears. Anybody concur? JB



For the 7.5" 10-bolt there is a 2-series carrier and 3-series carrier. If you use 3.xx gears with a 2-series carrier, you need to buy a R+P set with a "thick" ring gear. I'm not sure where the cut-off is for 8.5" and 8.2" rearends. Simply check with the gear vendor. I recommend Randy's Ring and Pinion for competitive prices and great tech support.

After a few internet searches, its seems the two 8.5" carriers are "2.56 and down" and "2.73 and up." Can't find much on the 8.2" rearend, but did see a carrier for "3.08 and up."



 
squidley63 
Member
Posts: 517

Loc: Ar
Reg: 09-23-04
07-21-07 09:54 PM - Post#1213786    
    In response to MikeB

Does anyone know what the physical difference is between 4 series and 3 series carriers is on a truck 12 bolt. I'm trying to get around 3 to 3.48 gears in the rearend of my truck from 4.10 gears and not sure where I can get the proper carrier.


1963 Chevrolet C-10 Fleetside SWB
400 sbc 3 speed manual

95 Chevy Suburban 5.7TBI 4X4


 
raycow 
Honored Member
Posts: 27084
raycow
Loc: San Francisco, CA
Reg: 11-26-02
07-22-07 04:37 AM - Post#1213852    
    In response to squidley63

  • squidley63 Said:
Does anyone know what the physical difference is between 4 series and 3 series carriers is on a truck 12 bolt. I'm trying to get around 3 to 3.48 gears in the rearend of my truck from 4.10 gears and not sure where I can get the proper carrier.



The difference is the location of the flange that the ring gear bolts to. As the numercal ratio increases, the pinion gets smaller in diameter, so the ring gear needs to be closer to the pinion centerline.

As for actually finding one, if you want the factory type open carrier you will need to locate a used rear end with 3.42 or taller gearing. This can be any truck 12 bolt up to the end of production. If you want posi, new ones are readily available from the aftermarket.

http://www.tomsdifferentials.com/catalog.asp?pg=12

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
shawnlee 
Senior Member
Posts: 459

Age: 47
Loc: so.cal
Reg: 06-19-06
07-22-07 10:03 AM - Post#1214049    
    In response to raycow

The 3 series is just that ,the 3 series ratios.....The 4 series {which you have}is for the 4 series ratios........You need a ring that has the t after the part number ,meaning it is a lower ratio intended for a larger carrier.
If you look closely at the ring gears it will say in the details which one fits which carrier.you could put 3.73 in there as thats the cut off for a 4 series carrier or use the ring gear with the t in the part number and go all the way down to 3.00 in a 4 series case.

Its gunna cost more and take longer,trUst me!!


Edited by shawnlee on 07-22-07 10:03 AM. Reason for edit: No reason given.

 
squidley63 
Member
Posts: 517

Loc: Ar
Reg: 09-23-04
07-22-07 05:11 PM - Post#1214311    
    In response to shawnlee

Appreciate the information guys...I was secretly hoping it was the other way around so that I could shim behind to get the proper gear mesh. Looks like I'm going out to the junkyards


1963 Chevrolet C-10 Fleetside SWB
400 sbc 3 speed manual

95 Chevy Suburban 5.7TBI 4X4


 
raycow 
Honored Member
Posts: 27084
raycow
Loc: San Francisco, CA
Reg: 11-26-02
07-27-07 06:58 AM - Post#1217855    
    In response to squidley63

Unfortunately, you can't do it that way. The thick ("T") ring gears or the spacers are made so you can run 4-series gears on a 3-series differential case. There is nothing you can do that will let you run 3-series gears on a 4-series case because the 4-series case flange is too close to the pinion cennterline.

http://www.tomsdifferentials.com/catalog.asp?pg=10

If you want to run 3-series gears (3.42 or numerically lower) your only choice is to install a 3-series differential case.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
68zz502fi 
Forum Newbie
Posts: 49

Loc: usa
Reg: 10-13-07
08-31-09 12:45 PM - Post#1763893    
    In response to raycow

there are now a few 3 series gears that fit 4 series carriers available through a few manufacturers.3 series gears specificly made for the 4 series carriers



Edited by 68zz502fi on 08-31-09 12:46 PM. Reason for edit: No reason given.

 
4dr 57 
Valued Contributor
Posts: 4494
4dr 57
Loc: Texas Hill Country
Reg: 11-10-04
12-04-09 10:10 AM - Post#1817681    
    In response to mlrailguy

  • mlrailguy Said:
I think this was clunking more than it should. Took cover off and all looks great. 2.56 so think I will go with some 3.08's I got for good price.




hey..I had a 3:08 in a 57 w/a 301 anna 4sp. out of a corvette at one time. I remember it would go 10 mph for every 1000rpm. 72 mph in first gear! By the top of 3rd I was walking past the 327 with the 4:56 but he got me by a length right off the roll.

It's all good. mostly




 
PoppaBill 
Forum Newbie
Posts: 8
PoppaBill
Loc: Austin, TX
Reg: 06-05-09
01-14-10 09:44 AM - Post#1842216    
    In response to 4dr 57

My '60 El Camino has the original 283 with 4bbl in it. T5 5-speed and either 3.73 or 4.11 rearend. Have been thinking about 350 crate in the 300-350 hp range. I'm kind of a newby and would appreciate thoughts/observations as to suitability of current rearend with the 283 as well as with possible swap to 350.



 
jb2wheeler 
Valued Contributor
Posts: 4340

Loc: Louisville KY
Reg: 05-09-04
01-14-10 10:09 AM - Post#1842233    
    In response to PoppaBill

  • PoppaBill Said:
My '60 El Camino has the original 283 with 4bbl in it. T5 5-speed and either 3.73 or 4.11 rearend. Have been thinking about 350 crate in the 300-350 hp range. I'm kind of a newby and would appreciate thoughts/observations as to suitability of current rearend with the 283 as well as with possible swap to 350.


If you are determined to use a small block, I would consider a 383 crate engine for that extra torque for a big car like your 60 Elky. I would keep the present rear end. JB


If you can't hum it, it ain't music! http://www.picturetrail.com/gallery/view?p=999&am p...


 
stefanP 
Forum Newbie
Posts: 22
stefanP
Loc: southington,Ct.
Reg: 05-24-10
05-25-10 05:22 PM - Post#1920632    
    In response to jb2wheeler

My 2 cents,If you consider driving on the highway at all,I wouldn't go any lower than 3.73 ratio.If you just plan to be in town or on roads with a 40mph speed limit,you could go a little lower.But this will also depend on what you have for a rear tire size.My for exsample my fiend had a 65plymouth satilitewith a 440/automagic and 4.11 gear and 55mph was just about max for a sustaned high speed.(sorry for the non chevy car).Good luck.
stefanP

If it's not broke,"DON'T FIX IT"


 
kitabel 
Contributor
Posts: 291

Reg: 11-28-09
05-29-10 09:48 AM - Post#1922396    
    In response to stefanP

3.08 + 2.20 flies like a bird with one wing below 40 mph.



 
Thadd 
DECEASED Member
Posts: 11178
Thadd
Age: 78
Loc: Rolling Hills, Ca,
Reg: 12-30-01
10-09-10 04:10 PM - Post#1987027    
    In response to PoppaBill

PoppaBill. Don't worry about that 60 rear end. The street cred is that the third members from 55 to 64 (55-62 Vette)interchange, and someone will say that that is the rear that those Super Stock 409's ran, so a mild street engine should survive forever.
FWIW, I run a 57 rear end. It has had 3.55 open, 3.70 posi, a 4.56 posi and a 4.11 open in it since I have had it. It has had a Super T-10 4 speed, two T-5 5 speeds, and a 700R4 4speed auto in it. My current engine is a 355 86 Vette with aluminum heads, Blower cam, A B&M 142 blower at about 8 pounds boost, etc etc. Knock on wood, after many many years of street driving, drag racing and just plain showing off, the rear has never had a hiccup. I suspect that you won't subject yours to any more abuse than I have
I am shortly (maybe next week) going to take out the 4.56 posi and slip the 3.70 in there. It really leaves hard with the low gears in both the trans and the rear, but I am trying to quiet it down and make it a little more traffic friendly.


Proud member of the BABY BLUE T-SHIRT BROTHERHOOD


 
USMCVietVet 
Very Senior Member
Posts: 2369

Loc: Enterprise Oregon USA
Reg: 05-22-02
07-31-13 06:04 PM - Post#2368148    
    In response to Thadd

My 67 Camaro has the 308 it came with 150 thou and going strong on it's 3rd engine --now a 302 out of a Z/28 (69)--4 speed Sag--runs well--you will like the 308's i think..

I was--glenn's 3rd 55 previously
55 chevy 210 2 door 350/4L60 RIP(gone)-and missed!!

-1967 CAMARO--red Z-28 /4speed

02 dodge diesel pickup chipped and no muff 6 speed
13 Honda Ridgeline
06 Honda Ridgeline
14 Honda CRF 250 L


Edited by USMCVietVet on 07-31-13 06:05 PM. Reason for edit: No reason given.

 
pdq67 
Member
Posts: 470

Loc: Columbia, MO, USA
Reg: 08-31-02
05-02-15 05:13 PM - Post#2544171    
    In response to USMCVietVet

'67 Camaro:

3.08, 3.36 and 3.70 are for a stock '67 10-bolt.

The 3.07, 3.31 and 3.73 are for a stock '67 12-bolt.

A wide ratio Muncie with a 2.52 1st gear really likes a 3.36, (10-bolt) and 3.31, (12-bolt).

A close ratio Muncie with a 2.20 1st gear likes a 10-bolt with a 3.70 and a 3.73 in the 12-bolt!

Now if you want to turn your tires and ta heck with gas mileage, install a 4.11 in the 10-bolt and a 4.10 in the 12-bolt.

I ordered my '67 350SS/RS Camaro wide ratio Muncie with a 3.31 posi.

pdq67





 
Broo102 
"3rd Year" Silver Supporting Member
Posts: 459
Broo102
Loc: RANCHO CUCAMONGA, CA.
Reg: 09-30-14
11-16-15 11:07 AM - Post#2589276    
    In response to 1FATGMC

Can you tell me where the ratio code is on my T-10?
I cant tell if I I have a super T-10 or?
my casting #s are: 13-04-065-904
built 11-31-81
thanks!
Bru

Thanks!
Bru
John 3:16
32 Chev. 5 Win. Sports Coupe
47 Chev. convertible in progress


 
pdq67 
Member
Posts: 470

Loc: Columbia, MO, USA
Reg: 08-31-02
11-17-15 04:09 PM - Post#2589646    
    In response to pdq67

Back again, I forgot that the '55 to '64 rear ends have a "pumpkin" like Ford's 9" has.

Makes for way easy rear end gear changes in the Tri-5's because you can pull a pumpkin in like 30 minutes once your car is up.

A side note!

The Tri-5's stick trannies hang off the bell-housings so the guys don't have to bother with removing a tranny cross member!

I knew a kid that I worked with way years ago on the RR that said he could drop a 4-speed out of a Tri-5 in like 5 minutes!!

He ended up in Reform School because he got caught by the po-po sliding one out.. He, He!!

And the 8.5 is a Corporate rear end that replaced the 12-bolt. Same input shaft dia. but only an 8.5" dia. ring gear vs the 12-bolt's 8.875" dia.

Now, this is way cool IF you can find it on the Boards?? Somebody documented reworking a truck 12-bolt rear end so that (I THINK???), it would take 12-bolt car gears.

I had it saved but lost it a while back...

pdq67



Edited by pdq67 on 11-17-15 04:14 PM. Reason for edit: No reason given.

 




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