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GM B-Body Forum, 77-79 Caprice/Impala Forum

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    700R4 in a '79 Caprice?

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    solo79
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    Posts : 457
    Join date : 2013-02-06
    Location : Kentucky

    700R4 in a '79 Caprice?

    Post  solo79 on Wed Jan 29, 2014 7:49 pm

    Ok, so I've been thinking about doing this and I'm wondering how difficult it would be to do. The newer cars have 700R4s in them, but my 79 has no computer at all. Would I have to have a computer out of a later car to engage the lockup converter? Would my stock cross member work? I'm assuming the drive shaft would have to be changed, but other than that I'm unsure. I put a TH350 in my first Caprice after the stock transmission locked up which I think was a 220 Metric and the 350 bolted right in. My current car had a TH350, but the owner sold it before I got the car.

    I was original going to put a TH350 back in it, but it sure would be nice to have 4 speeds for highway driving. I'm not looking to build much performance in this car, I have my 82 Trans Am for that performance itch.


    _________________
    1979 Caprice Classic Carmine Metallic 2-door 350/TH350 -under slow frame off restoration!
    1982 Pontiac Trans Am Black T-Top 327/TH350 -Knight Rider KITT replica
    1989 Pontiac Firebird Black T-Top 305/700R4 -nice sunny day daily driver
    1997 Chevrolet Silverado Ext. Cab 3rd Door White Vortec 350/4L60E
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    Sweet Seventy9
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    Join date : 2013-11-03
    Location : Upstate NY

    Re: 700R4 in a '79 Caprice?

    Post  Sweet Seventy9 on Fri Jan 31, 2014 1:39 pm

    solo79 wrote:Ok, so I've been thinking about doing this and I'm wondering how difficult it would be to do.  The newer cars have 700R4s in them, but my 79 has no computer at all.  Would I have to have a computer out of a later car to engage the lockup converter?  Yes and No..... You can use the factory or an aftermarket control module, but you can also just use a non lockup converter   Would my stock cross member work? No.  Use one from a 94-96 Impala SS.  It allows dual exhaust too.  I'm assuming the drive shaft would have to be changed, but other than that I'm unsure.  Use one out of a B body that has a 700r4 in it.  I put a TH350 in my first Caprice after the stock transmission locked up which I think was a 220 Metric and the 350 bolted right in.  My current car had a TH350, but the owner sold it before I got the car.  

    I was original going to put a TH350 back in it, but it sure would be nice to have 4 speeds for highway driving.  I'm not looking to build much performance in this car, I have my 82 Trans Am for that performance itch.

    Your speedometer will be off but there's info out there on how to fix it.
    Your column shifter will no longer be usable.  You can either switch steering columns and dash pods to overdrive ones to keep it factory looking, or simply pull the pin and remove the column shift lever and use a floor shifter.

    The TH700R4 prior to 1986 is weak in the 3-4 clutch area, later ones are better but could be made better still. Best thing is to repack the 3-4 clutch to use 8 plates instead of 6 - this requires a replacement clutch piston which is thinner to provide clearance for the additional two plates.



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    1979 Impala Coupe x2
    1979 Caprice Coupe x7, Landau x4, Estate Wagon x1
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    solo79
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    Posts : 457
    Join date : 2013-02-06
    Location : Kentucky

    Re: 700R4 in a '79 Caprice?

    Post  solo79 on Fri Jan 31, 2014 6:41 pm

    Thanks for the info. I was thinking about an Impala SS crossmember because the factory one I have, the previous owner beat it into submission to clear dual exhaust and it looks terrible, so I was going to replace it anyway, but didn't want to get a factory one if it wouldn't work with the 700R4. Definitely going floor shift with a console on this car and was planning on using a shifter assembly and shifter cable out of an 83-92 Firebird or Trans Am. I deal a lot in those parts, so getting those is easy. In fact, I already have the shifter assembly, actually I think I have two of them and a cable somewhere. They are nice trouble free simple 4 speed shifters that will accept numerous knobs. I just have to see if the cable will reach depending on where I mount the shifter to the tunnel.



    _________________
    1979 Caprice Classic Carmine Metallic 2-door 350/TH350 -under slow frame off restoration!
    1982 Pontiac Trans Am Black T-Top 327/TH350 -Knight Rider KITT replica
    1989 Pontiac Firebird Black T-Top 305/700R4 -nice sunny day daily driver
    1997 Chevrolet Silverado Ext. Cab 3rd Door White Vortec 350/4L60E

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