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[FONT="calibri" ]On the drop out 8.2 10 bolt rear end the carrier break is 3.70 and numerically lower which is a 2 series carrier and 4.11 and numerically higher which is a 3 series carrier. So if you are taking out a factory GM 4.11 gear set which would be a 3 series gear set and carrier you will have to change the carrier to a 2 series carrier in order to run a 2 series gear set of 3.55 or 3.08 ratio. [/FONT]
[FONT="calibri" ] [/FONT]
[FONT="tahoma" ]From:[/FONT][FONT="tahoma" ] odessa.design@telenet.be [mailto
dessa.design@telenet.be]
Sent: Wednesday, July 01, 2020 9:43 AM
To: Brown, Johnny
Subject: Re: Richmond Gear - TECHNICAL SUPPORT FORM[/FONT]
[FONT="verdana" ]I think so yes, its a pumpkin type with 10 bolt diff house.[/FONT]
[FONT="verdana" ]There is a posi traction inside but the housing is for a non posi differential I learned from the NCRS.[/FONT]
[FONT="verdana" ] [/FONT]
[FONT="verdana" ]regards[/FONT]
[FONT="verdana" ]Geert[/FONT]
[FONT="verdana" ] [/FONT]
[FONT="verdana" ]Van: [/FONT][FONT="verdana" ]"Brown, Johnny" <jbrown@midwesttruck.com>[FONT="verdana" ]
[/FONT]
Aan: "odessa design" <odessa.design@pandora.be>
Verzonden: Woensdag 1 juli 2020 16:06:25
Onderwerp: RE: Richmond Gear - TECHNICAL SUPPORT FORM[/FONT]
[FONT="verdana" ] [/FONT]
[FONT="calibri" ]Geert,[/FONT]
[/FONT]
[FONT="calibri" ] [/FONT]
[FONT="tahoma" ]From:[/FONT][FONT="tahoma" ] Richmond Gear [mailto:sales@richmondgear.com]
Sent: Wednesday, July 01, 2020 6:38 AM
To: salesRG
Subject: Richmond Gear - TECHNICAL SUPPORT FORM[/FONT]
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CONTACT US FORM DATA
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Name: Geert Waem Email: odessa.design@pandora.be Phone: 0032 470 182771 Type of Inquiry: technical How can we help you?: I would like to replace the 4.11 pinion gear in my differential by a 3.55 or 3.08.
My engine is a stroker and somewhat over powered for the 4.11 what makes it revving high and a bit nervous which is not in line with the rest of the car :-)
The posi inside is a 4 series.
So it seems not possible to mount a 3 series ring on the carrier.
Do you have this available to make it possible to mount a 3 series on my posi?
Hereby also the stamped codes FYI
Posi: 23618X 9 16 63 8
Ring: GM 3733908 / 9 37 (gears) 12 63
Diif house: 3789812 A274
Also would like to know if you should have these parts where I can purchase them(needs to be shipped to Europe)
thx
regards
GeertModel Year: 1959 Manufacturer: chevy-gmc-cadillac Vehicle Model: Corvette Axle Model: Solid axl with posi-traction in the pumpkin, probably from 1963/4 Current Traction Type: limited-slip-posi-factory-original Current Gear Ratio: 4.11 Transmission Model: Powerglide Comment
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Re: C1 pinion gear ratio
If your end goal is a car to drive mostly on road tours you are not going to be happy with 4:11 gears unless you have a six speed with two overdrives. Before you go wasting money think about what rpm you want to be turning at what highway speed you want to run comfortable at. If you look at todays cars most will cruise at 70mph at somewhere between 1800 and 2200 rpm. It will be very difficult to achive that with a 4:11 rear gear. There are plenty of rpm calculaters out there on the web (Silver Sport Transmissions) to help you with this. If you are seriously now considering a tranny change you need to decide which one before you decide on rear end ratio. I run a 383 stroker in my 62 and went from a 3:70 down to a 3:36, can still fry the tires in first but cruise at 70mph at 1900 rpm. Just my old two cents!Comment
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Re: C1 pinion gear ratio
Terry,
Have been doing some calculations as you suggested.
It indeed seems to be the better option to change the gearing as well as the tranny.
With the powerglide it will be difficult to get the revs down even with a 3.36 or 3.08 pinion gear.
This will be result ofcourse in an even higher budget I will need.
The 700R4 looks a reasonable option to me.
So probably now first change the gearing to 3.36 and start the search for a transmission.
What concerns the originallity I would like to maintain it as much as possible but the fun in the driving is quit important to and since I do not have the original motor....
Thanks a lot for your insights on this.
regards
GeertComment
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Re: C1 pinion gear ratio
If you have a cast iron powerglide and are not completely happy with that transmission, maybe the better option for more originality is an aluminum powerglide? At least it is a two speed, you can choose the converter to perform in the manner desired, and it is similar. Be certain to get the version that has the same overall length and you will not need a different driveshaft.
JoeComment
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Re: C1 pinion gear ratio
Joseph, please explain how the converter on a powerglide is going to help with lower rpm at cruising speed!Comment
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Re: C1 pinion gear ratio
That comment was not about rear ratio. He needs to decide what rpm he want at cruise speed and select a ratio.
Remember the application. A loose converter will not be a good choice for road tours.Comment
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Re: C1 pinion gear ratio
I'm not sure what you mean by loose converter, please explain! And again with a powerglide with a 3.08 rear gear at 2000rpm he is going 52mph. hardly cruising speed. He would be doing 2700rpm at 70 with the glide.Comment
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Re: C1 pinion gear ratio
hi- i can't speak to the details inside these rear ends or the exact rpm you would achieve with different ratios but can offer some info on how the car might perform. i recently swapped out my non-posi 3:08 for a posi 4:11 in my 270 h.p. 1959 with t-10 4 speed. the 3:08 had sluggish acceleration and the 4:11 are much more like you would want from a corvette. however, the car almost never goes on highway road trips and i agree the 4:11 revs too high for cruising. i don't know how much torque your stroker has but if it is a 383 like terry's and you change to a 4-speed i think a 3.55 might be a nice compromise. jim oComment
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