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Thread: Any advice on a 4 speed conversion?

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    New Guy
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    Any advice on a 4 speed conversion?

    I recently read a comment that a 4 speed conversion could be done using 3 speed linkage, the reverse was engaged using a separate cable assembly. I was hoping that maybe someone had advice and maybe pictures detailing this conversion?

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    Certifiable Vanatic
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    Welcome to VCVC! I have seen posts on this subject, try the Search function. What year van do you have? We love pictures...

    I want to replace my 66 three on the tree with a 200R4 or TH350 one of these days....

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    VCVC Member EZ Cool's Avatar
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    No pictures but it’s a simple deal. Hook the shifting rods up to the four speed just like they came off of the three speed. That makes first gear where reverse was on the tree. Second is where first was third takes the place of second and fourth is where third was. Instead of three on the tree plus reverse you now have 4 forward gears on the tree. Use a separate push pull cable for reverse.
    1970 Chevy Van 90 Three on the Tree with OD
    1938 Chevy Coupe
    1950 Chevy Sedan delivery
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    Welcome Aboard.

    Welcome Macbre-Improv
    As previously posted, it is a pretty straightforward retrofit. The original linkage is re-used and installed exactly as with a 3 speed. Since the column "spaces" would be filled up with the four forward gears, you can run a cable to engage reverse. Simply put the column shifter in the neutral position and then pull on the cable. There's several options on where to place the handle, like under the dash or on that doghouse bulge where the choke handle lives. I would advise a marine type cable since the push/pull effort can be stiff. The good marine type cables will have a thick center cable and a housing that has strands that run parallel to the cable. Stay away from the less expensive spiral wound stranding that you see on choke cables and small engine accelerator cables. When securing the cable, be sure to have the routing as smooth as possible (of course) and pay special attention to anchoring the cable from any movement. I'll try to post a pic of what I mean. With the significant pull required to engage reverse, over time the cable housing can move. If this movement is excessive, the pull on the cable handle will just move the cable housing and not engage reverse. I imagine that you'll be running a Saginaw 4 speed. This is the easiest retrofit since the main case and extension housing is the same as the 3 speed. If you haven't already picked out your 4 speed, keep in mind the 4 options available as far as internal ratios. This can be easily identified by the rings on the input shaft.

    A 4 speed can be a great way to add additional gear range to your VCVan. Done correctly, you can configure your van for better low-end around town and hauling capability or make it better on the high-end highway travel mode. Personally, I favor the 3 ring Saginaw 4speed with R10Q-1 overdrive. That combination gives me the widest ratio with 1st gear (3.50) and the highest ratio in OD (0.70). Now I need a 2 series carrier and a 2.73 or 2.54 gear set for my differential. I'm shooting for 1,500 rpm at 65-70 mph. That should give me some better fuel economy than the stock 3.36 rear axle ratio I have now.
    108VanGuy...
    1969 Chevy Panel, 250 CID, 3 ring 4 Spd. with OD, 2.73 "WedgieVan" Daily Driver
    1967 Chevy Panel, 230 CID, 3 Spd. 3.36 "UtiliVan Owned since 76
    1964 GMC Panel, 194 CID, 3 Spd. "CrunchoVan"
    1965 Chevy Panel 350 CID, 3 Spd. "RustoRoof" Runs but wiring bad
    1969 Chevy 108 Display 307 CID THM 350 Power Brakes 3.73 Posi
    1965 Chevy Panel, V8, 3 Spd. "Gold Hills Van"
    1965 CamperVan, V8, 3 Spd.
    1969 G20 Shell

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    New Guy
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    thanks for the info everyone! I am new to the community, and still learning about these vans. Living in the midwest, I plan to drive it a lot on the interstate for camping and other rural destinations. Just trying to raise some mpgs and lower noise. I have searched this sight and couldnt quite find what i was looking for right off the bat, plus i figured I could get a more experienced answer if i started a thread. When I find a saginaw 4 speed, I'll make sure to post pics.

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    Administrator smiley's Avatar
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    Quote Originally Posted by Macabre-Improv View Post
    thanks for the info everyone! I am new to the community, and still learning about these vans. Living in the midwest, I plan to drive it a lot on the interstate for camping and other rural destinations. Just trying to raise some mpgs and lower noise. I have searched this sight and couldnt quite find what i was looking for right off the bat, plus i figured I could get a more experienced answer if i started a thread. When I find a saginaw 4 speed, I'll make sure to post pics.
    The 4-speed isn't going to get you lower RPM or noise, nor better gas mileage. Final drive on all transmissions is 1:1, unless you have an overdrive.
    1966 Chevy Display, "Southern Belle"
    1968 Chevy, "Blue Overdose"

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    VCVC Member EZ Cool's Avatar
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    I installed a Saginaw App speed overdrive in my van. I was real happy with it. They’re pretty ha d to find now days.
    1970 Chevy Van 90 Three on the Tree with OD
    1938 Chevy Coupe
    1950 Chevy Sedan delivery
    www.ezcool.us
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    EZCool-What is an "App Speed Overdrive"?

    Here's some pics of the cable setup I'm using on the WedgieVan.

    Click image for larger version. 

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    This shows how busy the WedgieVan choke area can get. On the left is the reverse pull cable. Next is the choke cable, then comes the OD cable and of course the park brake handle.
    Click image for larger version. 

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    Here's a shot of how I am securing the cable housing. There's one retainer on the bell housing and another on the transmission bolt. I fabricated a small mount to fit the transmission bolt hole and then put a 90 degree twist in it so I could mount a 1/4" retainer.
    Click image for larger version. 

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    This shows the routing of the reverse cable and another cable retainer, yup, good ole zip ties. It's just temporary I hope.

    So that's my current solution for cable routing on a 4 speed with OD. Hope that helps.
    108VanGuy...
    Last edited by 108VanGuy; 03-09-2020 at 11:29 PM.
    1969 Chevy Panel, 250 CID, 3 ring 4 Spd. with OD, 2.73 "WedgieVan" Daily Driver
    1967 Chevy Panel, 230 CID, 3 Spd. 3.36 "UtiliVan Owned since 76
    1964 GMC Panel, 194 CID, 3 Spd. "CrunchoVan"
    1965 Chevy Panel 350 CID, 3 Spd. "RustoRoof" Runs but wiring bad
    1969 Chevy 108 Display 307 CID THM 350 Power Brakes 3.73 Posi
    1965 Chevy Panel, V8, 3 Spd. "Gold Hills Van"
    1965 CamperVan, V8, 3 Spd.
    1969 G20 Shell

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    VCVC Member EZ Cool's Avatar
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    Meant 3 speed overdrive.
    1970 Chevy Van 90 Three on the Tree with OD
    1938 Chevy Coupe
    1950 Chevy Sedan delivery
    www.ezcool.us
    Facebook Page

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    New Guy
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    yeah I noticed that the 4 speed has the same final ratio as the three speed. But maybe the range of the 4 speed means I can put in a taller diff gear? Are there any suggestions for ring and pinion ratios? Thanks again for pics and advice.

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    Ring and Pinion

    I had a 3 speed with OD in the WedgieVan running a 3.08 and it was great on the highway. I got over 20 mpg with that 250 w/1bbl. I changed out the rear axle because I had a problem with it. I only had a 3.36 available at the time. That change knocked my fuel economy down to about 17. The 3.08 is easier to obtain and can be used with our typically existing 3 series carrier but I am hoping to run a 2.73 or 2.54 if I can get it. That's probably going to be too tall for the 250 engine so my plan is to run a 292. The goal is high mpg for long distance travel. BTW, the tires I'm running are 215/70 15 Michelins on all 4 corners. I give up the raked look by having the same size tires but gain the ability to rotate the tires for longer life.
    108VanGuy...
    1969 Chevy Panel, 250 CID, 3 ring 4 Spd. with OD, 2.73 "WedgieVan" Daily Driver
    1967 Chevy Panel, 230 CID, 3 Spd. 3.36 "UtiliVan Owned since 76
    1964 GMC Panel, 194 CID, 3 Spd. "CrunchoVan"
    1965 Chevy Panel 350 CID, 3 Spd. "RustoRoof" Runs but wiring bad
    1969 Chevy 108 Display 307 CID THM 350 Power Brakes 3.73 Posi
    1965 Chevy Panel, V8, 3 Spd. "Gold Hills Van"
    1965 CamperVan, V8, 3 Spd.
    1969 G20 Shell

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