Performing Honda K24a3/AST5 6spd Conversion

Discussion in 'Workshop Forum' started by lookforjoe, Aug 11, 2019.

  1. lookforjoe

    lookforjoe True Classic

    I'm starting a new thread, now that I've moved from preparing for the conversion to actually performing it - only took almost a year to get to this point :D

    Preparing thread is HERE. 1st post has links and detailed info on parts / mods for the conversion.

    So, the bay is basically stripped and washed (except clutch & brake lines, not prepared to disconnect those yet)

    I verified my hoist setup works nicely, lifted the rear higher to make it easier to get into the bay

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    Cut the first section along the crossmember first. The pas side end of the cut needs a repair section where the original was rusted through.

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    Removing the pas side eng mount bracket led to this (note I also removed most of the rain pocket where the ign ECU lived at one time, I plan on mounting an AC accumulator there) :

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    I have to make a repair panel for this area

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    AFM and expansion tank brackets removed

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    Basic tools I used: Angle Grinder/Cutter, Sawsall, Spot weld drill, Hammer & Cold Chisel. Eye, Ear & Nose protection.Tried to vacuum debris as I went, to mimize amount of sitting loose metal particles. I taped/masked off the external 1/4 & rear tail section to protect the paint (not shown).
     
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  2. kmead

    kmead Old enough to know better

    Location:
    Michigan
    Was there a previous fiberglass repair in that area? It looks a bit nasty.

    Interesting on the removal of the rain water holder, do you think it has much of a structural function or just to hold the trims and electrical appliances on that side?

    Having the hoist on that secondary adjustable beam will likely pay off in the future as you get offset loads and the car wants to lean to the one side, you will be able to compensate by moving the lift point from left to right.

    Nice prep for what is coming.

    Given all the prep to the engine I am betting this will on the road again before school starts.
     
  3. lookforjoe

    lookforjoe True Classic

    Yes, there was fiberglass there.

    I don't see how the 'waffle' area of the rain tray plays any part in structural support. I'm going to try to leave the lower bridge.

    I would like to have it done before school, but I think with all the re-wiring, AC, etc., it will be more like end of Oct (if I'm lucky).

    Today I got a little more done. Tomorrow hopefully test fit the drivetrain.

    Got the large bulkhead opening cut out, used Darwoodious's pics for reference . Still have to trim the right rail.

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    Made a preliminary cut to the left rail, using FiatMonkey's last build for ref, pretty much just removed the existing scalloped area. Probably have to cut the underside back to the outer skin, but I'll wait until I test fit the drivetrain to finish that.

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    Removed the bridge between crossmember & trunk floor. Took hour & 1/2 to remove the dynamat to this point.

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    Last edited: Aug 12, 2019
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  4. lookforjoe

    lookforjoe True Classic

    Forgot to add a pic of the bulkhead being removed - this is how much actually comes off. It's less material than appears when you look at the remainder, as the end sections are more square.

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    Today I didn't get much done. I sectioned the right frame rail, using pics from Darin, I removed a pie cut from the upper & lower edge of the rail, then pushed the outer panel back in & welded it in place. I cut inboard of the outer edge, so I had the rounded edge to pein over the horizontal edge for a little more meat in the weld seam. I just had to weld something, to get a feel for how it's going to go from here :D

    Now the rail essentially runs straight back, instead of bowing inwards. About 1" narrower rail at the rear. Gives room for the pulleys, looking at other's photos.

    (Rodger's)

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    Ground back the welds, looks OK overall

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    Small hole along the bottom towards the rear where I blew through needs fixing
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    Last edited: Aug 20, 2019
  5. darwoodious

    darwoodious Darin Nelson

    Location:
    Seattle, WA
    Ahh, nice. That's a great idea. One less piece to cut and fit - just bend it in!
     
  6. lookforjoe

    lookforjoe True Classic

    Another slow day. Between the rain and working on an old Volvo for a good friend, didn't get much done. I focused on the cross member reinforcement

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    1" square tube .0625" (1/16th) wall. I had bought some 3/16" plate & tube stock, I feel that is just too heavy to use for anything on this job, so I returned it all & bought more .125" plate, angle & .0625" square tube stock for all the reinforcement areas.
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    Have to resolve this with a new top plate
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    Last edited: Aug 15, 2019
  7. lookforjoe

    lookforjoe True Classic

    Today I stripped the interior as needed, removed the throttle cable & pedal, the shifter assy & rod.
    After that I started fitting the subframe. Had to oversize the forward section outer holes and the stock subframe mount points. I cut the handbrake pulley cover, but I don't think I actually needed to.

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    My forward mount will clear the crossmember once I trim a notch in it

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    After all that, I centered the junction & welded it in place. That was a serious PITA working under the car.

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    Water pipe proximity to subframe - I have to bend them upward a tad.

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    Rear fit
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    Cut out the trunk floor

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    Last edited: Aug 15, 2019
    sub-zeroil likes this.
  8. sub-zeroil

    sub-zeroil True Classic

    Location:
    hollywood fl
    looking great sir !!!
     
  9. lookforjoe

    lookforjoe True Classic

    Thank you! How is yours running, it's on the road now?

    Spent the morning cutting out the remnants of the floor - I had to grind down the vertical lip that was welded to the frame rails and rear panel. It would have made a messy finish.

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    After that I cut the sections for the forward and rear cross bracing, the side lips & test fitted everything. I also raised the floor about half an inch or so, since I don't use the floor insert & to give a little extra room underneath.

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    The vertical lip was cut off the cross brace where the fore/aft lip needs to sit flush
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    Then I started welding the first crossbrace, and tried to seam weld the factory crossmember bracing where it meets the frame rail. That was a mess as the sealer/undercoat weeped out as I was welding, made a real mess.

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    This was a real PITA to weld - I had to stand inside the trunk to weld parts of it. I'm claustrophobic - it didn't sit well with me.
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    Tomorrow I'll move forward with getting the other two braces welded. After that, I'll go back to the lower crossmember repair.

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    Last edited: Aug 16, 2019
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  10. lookforjoe

    lookforjoe True Classic

    Before I started welding today, I made the repair section for the crossmember. My brake doesn't work for this guage Stainless. I was able to start the bend, but then had to basically hammer the angles.

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    Seam welded the upper inner lip of the control arm mount bracket, and the new panel along the top edge.

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    Have to grind back the top lip, get it nice & smooth

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    Welded the 2nd upper brace to the frame rails, and to the first brace. Seam welding the repair panel in progress below

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    Seam welded the control arm mount bracket lower edge here.

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    Tomorrow I'll get back to the trunk floor.
     
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  11. lookforjoe

    lookforjoe True Classic

    Pretty productive work today. Got the trunk floor reinforcements all set. Not going to drill & put rivnuts in until I have the insert panel ready.

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    Didn't want to lift the car from the rear unitl I had at least the PS frame rail closed off, so I worked on that. I cut sections from the removed bulkhead crossmember, I wanted the overlapped weld line to flow to the front edge.

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    Marker dots indicate where I drilled for spot welds
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    Welded the small section first, as that completes the frame rail behind the crossmember, running forward to the right rocker section

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    After that, I added the forward section; I drilled holes that aligned with the remains of the inner brace, (which I flattened in alignment with the new rail position) so I could spot weld the vertical junction for additional support. Top edge is lapped approx 1/8th" over the existing panel - I find it easier to weld the seams with an overlap.

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    Cleaned up the welds & primed

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    Hopefully tomorrow I lift the car & do the first test fit of the drivetrain.
     
    Last edited: Aug 18, 2019
  12. Dan Sarandrea (Phila)

    Dan Sarandrea (Phila) Waitin' On Parts...

    Location:
    Philadelphia, PA
    With all the extra work the four a-arm pickup points are supposed to do with the Midwest kit, would it be out of line to suggest beefing them up somehow?
     
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  13. lookforjoe

    lookforjoe True Classic

    I think all one can do, besides the extra seam welding, is add a beefy oversize washer on the offside of the mount ears to make them double-wall as are the insides where the subframe ears are already doing that. Don't forget it's also bolted vertically using the stock trans crossmember points.

    Today was a busy day. Went for about an 18 mile bike ride in the AM with my younger brother, trying to spend a little more time with him. After that (exhausting :D ) ride, I set about test fitting the drivetrain. I wanted to do it with everything attached, to make sure that works.

    A number of issues - The dollie I had the motor on didn't fit well over the engine hoist, so it was quite difficult maneuvering the mess under the elevated chassis, as I lowered it very slowly onto the drivetrain. Had to lever the motor several different ways as I lowered the chassis, in order to clear the torque mount arm & alternator, and then the throttle body (which I damaged as it pressed into the bulkhead by the gas tank), and then the trans by the left rail. Hopefully it's only the bobbin & not the shaft/butterfly. Didn't take pics during this process, it was so fiddly & I was kinda paranoid getting under the car with it suspended from the hoist.

    Anyway, it's in place and everything clears. A few adjustments will be needed.

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    Drivetrain sits level - same as chassis - very slightly lower on the left

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    Damaged bobbin. Clearance is fine once motor is in final position. I just have to install the TB after the drivetrain. Hopefully I can make the firewall pretty again :D

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    Wiring will need a little attention - as it sits right now the connectors are a little difficult to access. Plenum clears nicely on the left (right of pic)

    The harness plugs are pretty much directly behind the wiring harness aperture - which makes them awkward to access. I'll have to see if I can move the harness a little to the right for better access.
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    Plenum/runner clearance

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    Header - problems there

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    Forward mount has to be relieved for clearance, and slave looks like it may end up touching once I do that

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    trans clearance. I actually could have cut even less out at the forward end - at least a inch or so

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    Had to bend the lift hook - it was pressing into the rail. Only had to ease the outer well lip slightly (about 1/4") to give suficient clearance

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    Rearward webbing clearance off subframe with 1/8" spacer added under mount

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    Air filter & hose approximate placement

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    Reservior will likely go about here

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    Problem with header: it's angled about an inch to high at the collector, which is what I measured at the time I welded it compared to Rodgers

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    So, either I section the crossbrace or I have to redo the header. I might get away with relieving the forward brace only, I need less than an inch at the point the collector would contact the forward brace.

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    Last edited: Sep 30, 2019
    dllubin likes this.
  14. kmead

    kmead Old enough to know better

    Location:
    Michigan
    With your skills I would redo the header. The car is going to need all the structure you can offer it.

    The clearance of the web is concerning, with rocking under load, sagging of mounts, it likely will end up coming in contact with the structure.

    Bummer about mundging up the firewall and the TB.

    What’s the story about the clearance next to the Volvo based mount? It appears to be tight up to the structure, is that intentional?

    Dan brings up a good point, although it is difficult to add to the legs of the mount, one wonders if there should be a means of coupling the lower structure to the top of the box section using some projection welded areas to attach additional bracketry inside the section. Particularly as you have the right side fully opened up. Coupling the structure in that area with all the engine weight as well as the suspension loading into that area seems like a good idea to look into.

    Great to see the ongoing work. Nice job.
     
  15. lookforjoe

    lookforjoe True Classic

    Yeah. I really don't want a bulge in the floor pan to accomodate the header :D

    The rear webbing I should be able to grind back to give more clearance. I don't want to lift the motor & end up with driveshaft alignment issues.

    The Volvo-based mount has to be cut back. It's not pressing into the rail, but is up against it. Will make for nasty vibrations, besides hacking into the rail over time.

    I hope I can clean up the firewall nicely. Gas tank has to be dropped anyway before I weld the forward crossmember, so I can get behind the panel at that point & try to work the panel as flat a possible. I'm probably going to push it in a touch to make sure there is good clearance for the TB and the clutch slave below.

    My plan is to add diagonal bracing from the new upper brace to the lower crossmember, turning it into a "K" tipped over. I figured it's not providing much extra support if it's not joined to the lower member. I was thinking also about horizontal bracing to the frame rails, but I don't think that load direction is really relevant here. I'll figure that out once I start laying out the exhaust, to make sure I don't introduce additional redos.
     
    Last edited: Aug 19, 2019
  16. lookforjoe

    lookforjoe True Classic

    Plugging away at all the odds and ends that need addressing while in test fit mode.

    Removed the left front mount bracket & cut it back to clear subframe properly.

    This is the slave clearance off the bulkhead

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    Belt drive gap off frame

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    Then I worked on the shift cable routing. Tried on either side of the subframe, didn't like the angle on the left. Too close to axle & up against the motor mount that side. I would have also had to drill the subframe rear vertical to allow the cables to pass through & use the stock shifter rod location, Darin is doing something along those lines. So, I have them on the right. Temporary ties for now. Sits pretty close to the oil pan at the front corner, but I put a heat sheath over them when I'm done.

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    Drilled a new 1.5" hole in alignment with the cable routing

    Thinking about using the shift rod opening for the heater hose/pipe that needs to go up on the left side.
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    Pretty smooth arc routing up top

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    Played around with brake junction and clutch junction points. Pretty sure I'm going to have them in this general layout. Not sure about right side brake line routing yet. Clutch junction bracket will be welded to under side of rail

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    Then I fitted the torque mount & bracket, checked the drivetrain for level again, and welded it to hold until I drop the drivetrain at which point I will seam weld the bracket.

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    Then I checked the fit of the rad hoses - MANY thanks to all the measurements and pics taken by Rodger & Darin, my fittings all came out as hoped for.

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    Have to cut back the angle section off the heater tube (right edge of pic), and get a longer heater hose


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    Then I worked on the shifter. Positioned the support, and marked the location for cutting, drilled the corners and cut the inner pieces

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    Typical stress cracks can be seen here - not sure why the console flexes the sheet metal there. The forward cracks (of the four) must be from the shifter.

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    Cleaned up all the metal shavings & all set to weld tomorrow, then I can check the cable settings & make sure it shifts as it should

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    Removed the throttle cable tube as part of the process - it has to be repositioned about 10" rearward, according to the notes. The 4-rivet bracket also interfered with the shift arm

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    More tomorrow.
     
    Last edited: Aug 21, 2019
    Mechanogeek likes this.
  17. lookforjoe

    lookforjoe True Classic

    Hey Darin - question for you - did you consider cutting back the firewall where the stock harness feed through lies? There is just so little space there for harness routing by the intake support/harness junction, I'm thinking it might make sense to remove that section & increase the bay space where the harness/ wiring junctions lie.

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    Last edited: Aug 20, 2019
  18. lookforjoe

    lookforjoe True Classic

    Slow going today. All I got finished was the shifter install, and the heater feed.

    My version of the base plate differs from Rodgers - it's not a complete circuit. This became an issue when welding as it distorts easily in the open section. I tried stitch welding it with the set screws in & vice grips in a number of locations (forgot to take pics of that), but the provided set screws seize in the frame from the heat. I then put the shifter on top to act as a heat soak, but that meant sacrificing a number of the set screws, which I had to drill out & retap. I made them all M5x.08 (not sure what the provided ones were, SAE, I think) except two that I had to go oversize (M6x1) where the bit went off the center of the snapped screw..

    Anyway, finally got the frame welded in around 2pm, so I moved on to setting up the cables & check the adjustment

    I will need to revisit the open section, perhaps adding a joining plate on the outside. The reason the frame is open is because the pivot bolt head would interfere. Also found that the heim has to be set at just the right angle or it will tend to jamb once reverse has been engaged, and not want to release.

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    Cable routing will be thus:

    have to add a support bracket off the rear mount bracket to hold the cables off the crossmember / crossbrace
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    I'll figure out a nice securing bracket for where the cables run along the subframe
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    The main cable (gear select) was easy to setup. The problem for me came with the detent cable. I couldn't get it to enagage reverse unless I backed the sheath all the way out of the bracket the entire length of the threaded end

    Shown halfway through in thise earlier pic:

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    Since the cables are the same length and have the same relative offset in the shifter brackets and the trans bracket, this didn't make much sense. The only way I could get sufficient throw of the detent cable to engage reverse was to cut around 5/8-3/4" off the cable end at the trans, and shorten the heim at the detent arm by the same amount, to increase the pull. With that, I was able to secure the cable sheath in the bracket, with enough threads for the retaining nut to lock the cable. Also made sure there is just a little movement in each cable when the selector arms are jiggled, to make sure the gates were not being held out of or on the edge of proper alignment. The shifter gate feels very close - I hope it works in action as well as it feels now.

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    dllubin likes this.
  19. lookforjoe

    lookforjoe True Classic

    Dropped the gas tank today, so I could address the throttle cable / bobbin setup. Solder has cracked around the right vent tube, clearly been seeping for some time. Not enthusiastic about resoldering a gas tank. I think the deal is to fill it with water to make sure no fuel vapors remain. Have to research that.

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    With that out of the way, I routed the clutch & brake line/junction. Drilled along the lip & put bolts in from above to retain the junction and the clutch line

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    Clutch flex line junction will be over here. I'll weld the original retainer bracket to the rail. Have to fix the rust here when I do the bracket weld ing.

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    In the frame hole behind the tank, I found the bulk of the wadding that was missing from the front side of the tank. Would have a made a nasty fire when welding the swing arm mount if I hadn't checked

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    Will add this bracket to hold the shift cables off the crossmember, and possibly bolt a heat shield to

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    Shifter cables from above - detent cable was the one I had to shorten

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    EDIT - comparing my shifter cable offset from gates to brackets with Rodger's....

    The guide sleeve on his sits over the reverse lockout solenoid - mine is at least 2" rearward of that point....
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    ... I can move the entire bracket forward at least 2", maybe more. That will move the cable arc away from the rear crossmember and make the bend in the cables softer. Not sure it's worth remaking the mount bracket again. I'll have to unbolt the carriage & play with it.

    After that, I swapped out the slave cylinder for the original - but I didn't like the proximity of the banjo union to the bulkhead - was worse than the clearance I had with the revised version, so I swapped it back. Then I ran the throttle cable & sheathing to figure out routing/placement

    The supplied cable parts don't fit the K-Tuned arm, so I have to figure the best way to address that. I'll probably look for a stainless version, since this will get rained on
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    The bobbin is just too close to the bulkhead. I removed it & dismantled the TB, trying to figure out if I could rework it / flip the bobbin for more offset. After some deliberation I decided to just wallop the bulkhead.

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    Had to also indent the gas tank a touch to get it to fit nicely

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    I'll spend a little time when the drivetrain is back out cleaning this up & getting the panel as smooth as possible

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    Last edited: Aug 22, 2019
    Daniel Forest likes this.
  20. TonyK

    TonyK True Classic

    Location:
    Grimsby Ont Canada
    Welding a gas tank. I have done several over the years. Remove the fuel sender cover and let the tank breath. I have used a vacuum cleaner on blow to vent the tank outside of the garage. If the tank is dry and vented for a day, you can weld it without issue. I then plug all the openings using duct tape and put .5PSI pressure on the tank and spray the welded area with Fantastic House Hold cleaner. It will bubble if there is a leak.

    Impressive build, lots of head scratching. I thought I was the only one having issues.

    Well done.

    TonyK.

    Grimsby Ontario Canada.
     
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