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#1 |
Registered User
Join Date: Apr 2014
Location: Sumrall, MS
Posts: 381
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saginaw 3 speed with 308 gears, Pro'/Cons
Ok guys, I need opinions on anyone that had/has this setup and how its ran for you. I currently have a little over 450 hp in my 7 bolt Saginaw running into my 373's. I do way to much highway driving and the 3000 RPM for 60 to 65 is killing me. I want to keep the 3OTT.
So please let me know any experiences if you have a nice street motor/Saginaw/ and 308's. RPMS at cruising speeds would be huge! I don't race or pull anything Will I have much problems on take offs with having to slip the clutch to much? |
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#2 |
Registered User
Join Date: Jul 2011
Location: Whitney Point, NY
Posts: 90
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
Other than a stock 307 I'm in the same boat, 3000rpm at 65 and not likeing it. I've considdered swapping out the 3OTT for a 5sp but I need to spend money on my engine first. Not sure I'd want to swap for 3.08's because I haul firewood with my truck and looking into a trailor to tow my tractor. Maybe the 3.08's and 4sp with granny gear would work out better ?
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#3 |
Registered User
Join Date: Apr 2014
Location: Sumrall, MS
Posts: 381
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
Also does anyone know how to identify if I have a 3 or 4 series carrier? Or does it have to be taken out!
Yeah mine is strictly a cruiser. I aint pulling anything lol. Pretty sure I am going with the 308's |
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#4 |
Registered User
Join Date: Apr 2014
Location: Rowlett, Texas
Posts: 20
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
Not sure how helpful this is, since my engine is pretty stock and I don't have a tach so I don't know what RPMs I'm running at. I do have a 3OTT with a 350 and 3.08 out back. Around town driving the way I do I get roughly 8mpg, however when I was in the Army driving home to Dallas from Ft. Leonard Wood, MO I would average anywhere from 20-25mpg for a tank, depending on traffic/wind at 70mph.
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#5 |
Registered User
Join Date: Jan 2003
Location: Gulfport Ms
Posts: 401
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
I have a 70 c10 with a mild 350 (RV cam) with a Saginaw 3 speed and
a 3.08 differential. It was originally a 3.73. I have had it about 35 years and tried many different things. The gas mileage was greatly impacted when I built the 3.08. It made a lot of difference. The main problem I have had is getting the speedometer corrected. It is about 15MPH slow. After a massive amount of research on the net and other sources I gave up. If I remember correctly, I needed a green gear in the housing. It was still carried in the Chevy parts dept. but was unavailable. There was a fellow in Calif. that made a unit that was guaranteed to correct it. I made a lot of measurements and ordered it. It made the speedometer 15MPH fast. I don't live far from you. If you will PM me, I will give you the mileage in distances that you will understand. BTW, Welcome to the board. EdB |
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#6 |
Registered User
Join Date: Apr 2014
Location: Sumrall, MS
Posts: 381
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
I actually have the green gear in the Saginaw and the speedo gear is green as well
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#7 |
Registered User
Join Date: Mar 2013
Location: Clifton, Maine
Posts: 86
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
Will I have much problems on take offs with having to slip the clutch to much?
Not with 450hp!! |
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#8 |
Registered User
Join Date: Feb 2012
Location: Ruskin Florida
Posts: 4,560
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
With 450hp I would start looking for my new transmission.
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#9 |
Registered User
Join Date: Apr 2014
Location: Sumrall, MS
Posts: 381
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
The Saginaw has been holding up well so far but I am already saving up for a auto gear m22 wide ratio. Going to make a 4 on the tree with a pull handle reverse. I am pretty easy on it with no burn outs or speed shifts. The motor put out about a 100 more hp than expected on the dyno. 472 hp
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#10 |
Registered User
Join Date: Feb 2012
Location: Ruskin Florida
Posts: 4,560
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
Doh! Nice.
__________________
70 swb 4x4 406sbc 700r4 203/205 d60/14blt locker yadda yadda http://67-72chevytrucks.com/vboard/s...88#post6935688 Yeller 72 Blazer 2wd conversion project "No Daggum Money" http://67-72chevytrucks.com/vboard/s...d.php?t=550804 LS1-T56 3.73 LSD super budget build Blanco-2014 Sierra SWB https://67-72chevytrucks.com/vboard/...d.php?t=810350 |
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#11 |
Hittin E-Z Street on Mud Tires
![]() Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
You seem to have two problems.
1. You want a lot of power. 2. You want lower RPMs. Those don't normally play well together, that's why we have OD transmissions. If you go from a 3.73 to 3.08 you're going to lose a good bit of the off line acceleration you're used to (why have all that power if you can't "make it go?") But if you don't, you'll have the truck screaming at you. If you don't care about the "power loss" then a 3.08 is a good option. If you want to keep the power you have, you're only real option is some form of OD.
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Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride ![]() American Born, Country by the Grace of God ![]() 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! |
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#12 |
I am a Referee of life.
Join Date: Jun 2000
Location: Greensboro N.C.
Posts: 13,993
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
I agree with Redneck. And I wouldn't even consider a swap to the 4 speed.You would only gain a lower gear and a shift since all the transmissions of the era were a 1:1 final ratio or less.I would love to see an option where I could lower the RPM's and keep the TOT without selling my house.I even did a little research on the GV OD and didn't find an adapter for it. Most claim the 700R4 or 200R4 does well with the 3:73 and that makes sense since the non towing package for most was a 3:42 and the 3:73 would give just a touch more grunt at the line.But it's not offered for the original carriers in the 1/2 tons. So far I haven't come up with an option that works for me. Don't forget to consider tire diameter with calculations for speed/RPM when coming up with your plan.
BTW That screaming of the higher RPM's usually stems from people who have been driving the newer vehicles with od and lower Rpms.It was pretty normal back when these were "late model" trucks. Still would be nice to have better mpgs and higher cruise speed.
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The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil" |
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#13 |
Registered User
Join Date: Apr 2014
Location: Sumrall, MS
Posts: 381
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
giving up the power is not a problem for smooth cruising to me, Again the motor made a great deal more power than I anticipated anyway. I am going to try the 308's
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#14 |
Registered User
Join Date: Apr 2014
Location: Sumrall, MS
Posts: 381
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
anyone know what tranny color gear sets to use for 308's?
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#15 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,602
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
Look here for speedo gears.
http://www.transmissioncenter.net/sp...n_______va.htm If you really do have 450 plus hp your motor won't be happy at a lower rpm. But you'll find that out soon enough. |
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#16 | ||
Vintage 4x4s
Join Date: Sep 2010
Location: Prior Lake, MN
Posts: 4,305
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Re: saginaw 3 speed with 308 gears, Pro'/Cons
Quote:
Quote:
Although more work for stevo,since it involves swapping to 3.08 and trans change, once installed a non granny 4spd may be just as good (if 1st is low, but not granny low) as a trans with overdrive and 4.10 especially and probably 3.73. You gain more than an extra shift (if going to 3.08), you gain closer ratios while having almost the same final drive ratio as an OD truck. I don't know about keeping the column shifter though.
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67 GMC K1500 Custom- 305V6 SM420, PTO, Ram Assist, yellow (the outcast) (project period correct upgrades) 67 GMC C2500 351V6 TH400, AC, PS, PB (can't decide what to do with. Update, decided to keep and will restore ![]() 86 CHV K30 502 th400, apple red NEW 71 CHV K20 350 SM465, ochre (saved work truck) 71 CHV K20 292 SM465, white, tach, PTO, (future project) 72 CHV K20 350 350th, medium blue (project stocker) 01 CHV K2500hd crew, indigo blue ^3 dont run and the others don't see winter either '86 K30 Cummins "Fireside" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=649649 '71 K20 "get driveable" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=590642 '72 K20 Build Thread: http://67-72chevytrucks.com/vboard/s...=493477&page=6 Last edited by Vintage Windmills; 08-02-2014 at 02:09 AM. |
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