700R4 to Saginaw 3-Speed Swap

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Colby83

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As the title states (and as some of you know), I'm swapping my 700R4 for a Saginaw 3-speed, not vice versa. I'll also let this post double as an introduction.

Hi, I'm Colby, and I'm a college student. I got my truck from my dad last April, nearly 21 years after he first bought it. He mainly used it to haul furniture and junk, which we didn't have to do very often, and I learned to drive in it. I loved riding in it as a kid. Last April, the real estate agent trying to sell the house across the street wanted the truck off the street cause it was registered non-op. Naturally, I parked it in the front yard instead. Bet that wasn't the outcome she wanted. My mom was actually going to make my dad get rid of the truck until I insisted that I wanted to keep it. Fast forward to today, and I've replaced all the broken gauge sending units, pulled the radiator and got it washed and sealed, flushed the rest of the cooling system, replaced/upgraded the entire fuel system between the tank and IP, hooked up a switch for full manual glow plug control (not just an override switch, the glow plug controller has been relocated into the garbage can), 3D-printed an intake hat for a cone filter, and installed a bed stack, among many other minor fixes and mods. Glad to be a part of this forum.

So, I spent all afternoon pulling the column and brake pedal and getting the manual pedals in. My truck's original brake pedal bracket had two studs and two holes for mounting. The hydroboost mounting bracket has two corresponding sets of holes and studs. The manual pedal set I got had four studs. I'm assuming this is just a hydroboost vs. vacuum booster difference. I ground, drilled, and hammered out the top two studs from the manual pedal bracket. The pedal bracket still wouldn't mount. I realized the holes weren't big enough, so I ground them out further. They're now about the same size as the holes on the original brake pedal bracket. They finally fit. I stopped here for today as it started pouring the second I got the pedals bolted in.

I'm going to reuse my auto column. I've seen a few people mention a blank shift bowl, GM 7812754. I tried looking it up and didn't get any hits. Does anyone have one of these floating around by any chance? If not, maybe I'll scan the current shift bowl, erase the nub, and 3D print it.

Merry Christmas,

Colby
 

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Ricko1966

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As the title states (and as some of you know), I'm swapping my 700R4 for a Saginaw 3-speed, not vice versa. I'll also let this post double as an introduction.

Hi, I'm Colby, and I'm a college student. I got my truck from my dad last April, nearly 21 years after he first bought it. He mainly used it to haul furniture and junk, which we didn't have to do very often, and I learned to drive in it. I loved riding in it as a kid. Last April, the real estate agent trying to sell the house across the street wanted the truck off the street cause it was registered non-op. Naturally, I parked it in the front yard instead. Bet that wasn't the outcome she wanted. My mom was actually going to make my dad get rid of the truck until I insisted that I wanted to keep it. Fast forward to today, and I've replaced all the broken gauge sending units, pulled the radiator and got it washed and sealed, flushed the rest of the cooling system, replaced/upgraded the entire fuel system between the tank and IP, hooked up a switch for full manual glow plug control (not just an override switch, the glow plug controller has been relocated into the garbage can), 3D-printed an intake hat for a cone filter, and installed a bed stack, among many other minor fixes and mods. Glad to be a part of this forum.

So, I spent all afternoon pulling the column and brake pedal and getting the manual pedals in. My truck's original brake pedal bracket had two studs and two holes for mounting. The hydroboost mounting bracket has two corresponding sets of holes and studs. The manual pedal set I got had four studs. I'm assuming this is just a hydroboost vs. vacuum booster difference. I ground, drilled, and hammered out the top two studs from the manual pedal bracket. The pedal bracket still wouldn't mount. I realized the holes weren't big enough, so I ground them out further. They're now about the same size as the holes on the original brake pedal bracket. They finally fit. I stopped here for today as it started pouring the second I got the pedals bolted in.

I'm going to reuse my auto column. I've seen a few people mention a blank shift bowl, GM 7812754. I tried looking it up and didn't get any hits. Does anyone have one of these floating around by any chance? If not, maybe I'll scan the current shift bowl, erase the nub, and 3D print it.

Merry Christmas,

Colby
Merry Christmas to you to sir,best of luck with your project..
 

Colby83

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Merry Christmas to you to sir,best of luck with your project..
Thank you. I talked to Peter from Steering Column Services earlier, and he gave me a few options for the shift bowl. I'm most likely just going to have them shave the nub off of my current shift bowl and fill in the hole. All the other options seemed pretty convoluted.
 

Colby83

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All done with the swap.

In my infinite wisdom, I initially installed one of those adjustable M-shaped aftermarket crossmembers as I didn't want to drill new holes in my frame. It didn't cross my mind that it would be directly in the path of the shift linkage. It also came with grade 2 fasteners despite the eBay listing claiming that they were grade 8. It was $40, so I guess I got what I paid for. Lesson learned. I ended up using the factory crossmember and moving it two sets of holes forward. I needed to drill new holes on the driver side. The 700R4 driveshaft works, but the slip yoke and center slip joint are a bit more exposed. I'm eventually going to get a single-piece driveshaft. A two-piece driveshaft with a direct drive trans and highway gears is just unnecessary (and I'll never have to waste my time fixing or replacing a carrier bearing again).

I ordered the shift linkage stuff (frame and bellhousing ball studs, ball seats, and springs) from both USA1 Industries and Classic Parts of America. The USA1 frame ball stud didn't fit the Z bar bracket I got (needed oversized washers), but the Classic Parts ball stud fit perfectly. Also, the USA1 clutch fork return spring was funny. I was able to force it into the hole in the frame where the stock return spring goes, but it was definitely overstretched. They called it a firewall clutch fork return spring. What? Anyway, for anyone else interested in doing a manual swap without a donor truck, I'd recommend buying the clutch linkage from Classic Parts of America. You might still have to buy the frame ball stud retainer spring clip from USA1 though. I don't remember seeing it on Classic Parts. Also, does anyone know what size the Z bar grease fitting is? I just left the hole empty for now.

The Saginaw 3-speed will probably last quite a while behind the anemic 6.2, but I'll need a Muncie 330 to put behind the Optimizer 6500 (AM General's bulletproofed 6.5) I plan on swapping in eventually. I guess I'll cross that bridge when I get to it. Why a 3-speed? I just think they're cool. Power band? Get an Allison if that's what you're worried about :Big Laugh: It takes a certain level of eccentricity (and stupidity) to put a 3-speed behind a diesel. I'm that stupid eccentric.

Cheers,

Colby

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I guess I'm a weirdo because I absolutely love what you have done, lol.

I'm not sure about the grease fitting, I'd guess it could be different from stock, if the z-bar is aftermarket.
 

Colby83

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I think you were the first to show interest in this swap. Thanks for the support man.

I'll worry about the grease fitting over the summer. I'm flying back to college later tonight.
 

mcarlo86

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There is just something cool about a 3 speed on the floor. I like seeing threads like this with guys doing interesting and different things besides the typical LS swap or swapping out a manual for an automatic. Well done!
 

Colby83

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Appreciate it! I'm not a fan of LS swaps either. I'm not exactly a purist (I was looking up ways to mate a Ford toploader to a Chevy engine earlier), but something about putting a late model engine in a classic truck rubs me the wrong way. Half the appeal of old trucks to me is the lack of computers. The last thing I'd do is add computers to one. And don't get me started on the hideous chrome donk wheels and rubber band tires that usually accompany those swaps. I guess I'm not one to talk. My bed stack isn't a mod most would consider tasteful :Big Laugh:
 

JBswth

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Merry Christmas to you to sir,best of luck with your project..
What is your rear end ratio? With a manual trans, you need shorter gearing, or else it will be "boggy" and gutless feeling. With a straight manual transmission, I would put a 3:73 or 3:55, depending on how and where you want to drive it.

J. B.
 

Colby83

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What is your rear end ratio? With a manual trans, you need shorter gearing, or else it will be "boggy" and gutless feeling. With a straight manual transmission, I would put a 3:73 or 3:55, depending on how and where you want to drive it.

J. B.
It is indeed boggy with the current 3.08 gears. I only got to drive it for a couple days before having to leave for college, but I did have to slip the clutch quite a bit from a stop. My dad has been driving it on the weekends, and he's had the same complaint. I'm actually hoping for 4.10 gears in the 14 bolt semi floater I'll be swapping in (dad's coworker is parting out a junk 6.2 diesel C20) when I'm back home for the summer. I'm sure most people would complain about 4.10 being too low without OD, but I'm fine with cruising at 55 on the highway. It's not like an NA 6.2 is capable of going any faster uphill with 3.08 gears, LOL. This means I'll have to keep my two piece driveshaft, which I've learned is much heavier duty than a single piece driveshaft anyway. Also, I'll be doing a lot more than just an 8-lug conversion following the 14 bolt swap... stay tuned.

-Colby
 

JBswth

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It is indeed boggy with the current 3.08 gears. I only got to drive it for a couple days before having to leave for college, but I did have to slip the clutch quite a bit from a stop. My dad has been driving it on the weekends, and he's had the same complaint. I'm actually hoping for 4.10 gears in the 14 bolt semi floater I'll be swapping in (dad's coworker is parting out a junk 6.2 diesel C20) when I'm back home for the summer. I'm sure most people would complain about 4.10 being too low without OD, but I'm fine with cruising at 55 on the highway. It's not like an NA 6.2 is capable of going any faster uphill with 3.08 gears, LOL. This means I'll have to keep my two piece driveshaft, which I've learned is much heavier duty than a single piece driveshaft anyway. Also, I'll be doing a lot more than just an 8-lug conversion following the 14 bolt swap... stay tuned.

-Colby
Yes, you can use 4:10, as long as you don't mind staying in the slow lane. There is also 3:73 gears and 4:56 gears.
 

Ricko1966

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Was reading some of your previous posts. There was more than 1 saginaw 3 speed and they had different gear spreads and gear ratios. I know for sure there were 3 I think there maybe 4. So you might compare what gearing you have now to what the factory offered for gear ratio with your engine and rear gear. As for a 1 piece drive shaft vs a 2 piece drive shaft they used 2 piece to prevent vibration. The longer the drive shaft the more support it needs to not whip. Looked some stuff up for you. Looks like a 2 line would be a good fit.
 

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