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Thread: trans swap

  1. #1
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    Default trans swap

    I kno this has been beatin to death but im starting to save up to swap out my 88's 4+3 to a t5 mainly becasue im paranoid do to the bad reviews. Anyway even if i buy a t5, a new clutch, throw out bearing, pressure plate and the cbeam adapter my local corvette shop still wants $1,500 to do the swap which seems steep to me, anybody know of any place in NJ that can do it cheaper?

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    1500 to do a transmission swap seems "steep"?! I'll admit it's not cheap but it's also not a rip.

    Ask you self...after you've spent all the money for the trans, clutch and etc, do you really want cheap installation.

    Also, if durability is of any concern, the T5 is marginal strength-wise in a stock C4 and, if the engine is modified, it's lacking in torque capacity.

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    yea ive heard the t5 is not going to handel the torque of the vet but at the same time the t5 is only a $350 trans so if that goes, once the vet is set up for a t5 I can swap it out myself

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    $1500 seems step to me considering they only have to swap the trans out and
    install a pre made adapter. The driveshaft shortening is the only variable

    From anesthes's excellent T5 swap page
    1984-1988 Corvette C4 T5 Swap

    Answers all your questions

    4+3 to T5 Swap Minimum parts list:

    1) T5 transmission from 1983-1992 V8 Fbody (Camaro/Firebird) ($100-250 used)
    2) Cbeam adapter from PRO STREET CorvettePage ($175 NEW)
    3) T5 hurst shifter OR mustang shifter ($50 used)
    4) Electronic VSS out of an 86-90 Firebird #10456087 ($20 used)
    5) Driven speedo gears for your rear end ratio ($20 NEW)
    6) Misc Materials - Fiberglass, screws, electrical tape ($30-40)


    Swap can be done for $400 - $600

  5. #5
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    Quote Originally Posted by Hib Halverson View Post
    Also, if durability is of any concern, the T5 is marginal strength-wise in a stock C4 and, if the engine is modified, it's lacking in torque capacity.
    I'm not trying to rain on your parade but you may be swapping out more T-5's than you think. I have exploded like 5 of these things in various mustangs. 2 with stock 225 HP 300 FTLBS engines. Ive built several in the garage.

    Third gear is CAST metal. THe teeth fly off this thing with a single missed shift. I dont care if its brand new, they still come apart.

    at least consider a stronger world class T-5 or ultimately the Tremec may live.

    The L98 could split the case on this trans with no problems.

    In my opinion if you go back with a stock ( $350) T-5, your going to get real familiar with changing them.

    If durability is your issue, your changing a stronger trans out for a weaker one. Why do you think GM never put a T-5 behind the L98 to begin with ?
    It was used in the 305 Z-28. However, no 350 ever had one.

    THere is a reason for that.

    One final comment, if you get a T-5, never ever nail the gas in reverse Its gauranteed to break that way

    Just my 2 cents.

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    thanks for the feedback..what manual trans mission was used in 350 fbodies during the 80's than? and will that fit into my vet?

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    Also this one shopthat specializes in 4+3 transmissions, there called SK transmissions (they have a website) keeps warning me about a "1st bearing" that goes bad in the 4+3 what is this bearing and how do i kno if mine is bad??

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    Quote Originally Posted by Oldskool153 View Post
    warning me about a "1st bearing" that goes bad in the 4+3 what is this bearing and how do i kno if mine is bad??
    The trans is just a BW Super T10 ; a durable well proven if old design gearbox.
    The problem area is the O/d unit. If not serviced at the recommended intervals 12K , then potential problems combined with design faults in the early years.

    The bearing you refer to is in the O/d unit.
    Nash Overview

    Read for background info
    Corvette 4 + 3 Overdrives
    Ken Stapel's Corvette Obsession - Doug Nash Information

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    Member JimBobC4's Avatar
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    Quote Originally Posted by Oldskool153 View Post
    thanks for the feedback..what manual trans mission was used in 350 fbodies during the 80's than? and will that fit into my vet?
    From like 1967 to 1981 the small block F body had a T-10 or a super T-10, I think. (except for the 302 Z28 and Lt-1 Z28 which had a Muncie)

    Been a while but I've owned six F bodies '67, '70, '74, '75 , '93 and '96

    Same trans as the Vette without the OD.

    If your 4+3 is working great now I say drive the thing !

    I have personally abused this transmission beyond what any normal human would ( Hey it was my buddies 1987 coupe and we were at the strip ! )

    We did tear the center out of the clutch once, but the OD and the gearbox stayed together. The car was sold with 168k HARD miles on it.

    Same gearbox.

    if you must change to T-5 keep in mind that 5 or 6 version exist.

    Dont pay 350 for a trans of unknown origin. It could be from a 4 or 6 cyl. 'Stang. Make darn sure its a world class late model ( from 1989 to 1998 I think) The best one is the T-5 that was put in the Cobra.

  10. #10
    MBDiagMan
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    Do I understand you correctly? You are saying that you are replacing your 4+3 because you think that it MIGHT give trouble?

    If so, this just doesn't sound like a prudent thing to do. I've had my 4+3 Vette 16 years and 122,000 odd miles. I have replaced a switch at the bottom of the shift lever and replaced the coil inside the transmission pan. I have also replaced the filter and changed the fluid twice.

    I would say that is pretty trouble free driving. If driven reasonably and maintained properly, these are tough units.

    It just sounds like a waste of money to replace it because it MIGHT give trouble.

    If it is working properly right now, change the filter and fluid, check the lubricant in the gearbox and enjoy!

    My $0.02,

    BTW: Are oldskool and I the only ones on this forum with unmolested 4+3's? Doc

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    Quote Originally Posted by MBDiagMan View Post
    . If driven reasonably and maintained properly, these are tough units.

    Properly being the operative word.
    Because the O/d was different ,many mechanics treated them like a regular automatic and did not do the scheduled fluid/ filter changes.

  12. #12
    MBDiagMan
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    oz,

    Yes, that's not the only thing that was misunderstood about them. This was an item that brought out the lack of technical understanding present in many techs. Unfortunately there are too many techs that are nothing more than parts changers, with no theoretical understanding.

    The 4+3 is DIRT simple! There is a switch, a connection from the ECM, a connection at the transmission, a coil inside the valve body that operates a check ball and everything else is just a component from other cars of which any tech should be intimately familiar.

    One switch, one electrical connection at the transmission, one coil and one check ball proved to be way too much rocket science for most of them to handle. As a result these transmissions earned a bad reputation that they did NOT deserve.

    One simple electrical circuit and a filter and fluid to change is ALL that makes this any different than other transmission components.

    A fluid and filter change every once in a while along with tracing of one simple circuit occasionally is ALL it takes to keep these things going.

    End of rant!

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    lol yea, i have done alot of rescearch about the 4+3 and the more i learn the more I like it. I posted a thred yesterday becasue I noticed when im in 2cd gear with the OD off right as im about to upshift the rpms somtimes jump from 25 to 35...i dunno what could cause that becasue it only does it in 2cd

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