Flexplate Replacement Parts (+ tangential component replacements)

[Zeb]

Parts #9 and #5 are worth replacing while you are down there. Replacing all those parts now will mean that when you go get the alignment, you won't find more worn pieces - and the alignment will "stick" and stay like they set it...

Thanks!
I mistakenly posted the diagram for a m1009 above (m1008 tie rod diagram below), but I get what you are saying. I'm ordering #10-14 from Advanced Auto Parts right now.

 

[Mullaney]

Thanks!
I mistakenly posted the diagram for a m1009 above (m1008 tie rod diagram below), but I get what you are saying. I'm ordering #10-14 from Advanced Auto Parts right now.
View attachment 855730

.
Definitely a good plan and depending on how old you are - you may never need to do anything on that part of the truck as long as you live. Excepting a spot of grease regularly

 

[Zeb]

After a longer test drive today, on both back roads and highway, with multiple stops to adjust the vacuum regulator:

• No death wobble, steering is tighter (though not as tight as I thought it was yesterday during my short slow test drive), ride is smoother
  • hoping that the CraneAxle Kingpin Spring Eliminator Kit, along with new Kingpin bushings and front tie-rod assembly will further tighten up the steering.... hope to install all of this over the coming weekend if everything gets delivered in time
• Truck still pulling hard left when I brake
  • haven't gotten around to inspecting the brake system yet, but I'm suspecting a stuck caliper or faulty brake line on the right
• I've got it shifting 1->2 at about 12-14mph and 2->3 at about 30-32mph. Shifts are firm.
  • ^That's with the vacuum regulator swiveled as far as it will go towards the radiator.
  • Paying closer attention today, with the vacuum regulator swiveled as far as it would go in the other direction (towards the firewall), it was shifting at about 8-10 & 20-22.
  • For reference, with a new regulator and modulator, my unit currently offers adjustable shift points ranging from approximately:
    • 9mph to 13mph for shifting from 1st->2nd
    • 21mpg to 31mph for shifting from 2nd->3rd
  • That range is tighter than I expected, as I'm not able to get the points up to 15 and 35 like some have suggested (granted it was meeting/exceeding those values before replacing the modulator, though was also not responding to regulator adjustments)
    • thus I am thinking something still isn't quite right
      • maybe some of that crud that I saw in the modulator got sucked up into the vacuum hard line and is impeding suction...
        • will check the vacuum pressure at all points down the line once again to make sure the readings aren't off, but I'm considering just replacing the hard line (since I've seen so many other posts from folks on this site who did that and it solved their shifting problems)
      • though with my current shift points at ~13mph & 31mph, I'm tempted to just leave well enough alone.... but a small part of me is worried that whatever little gremlin is still there will fester and end up expediting wear on the transmission.... what would @cucvrus do?

 

[ezgn]

After a longer test drive today, on both back roads and highway, with multiple stops to adjust the vacuum regulator:

• No death wobble, steering is tighter (though not as tight as I thought it was yesterday during my short slow test drive), ride is smoother
  • hoping that the CraneAxle Kingpin Spring Eliminator Kit, along with new Kingpin bushings and front tie-rod assembly will further tighten up the steering.... hope to install all of this over the coming weekend if everything gets delivered in time
• Truck still pulling hard left when I brake
  • haven't gotten around to inspecting the brake system yet, but I'm suspecting a stuck caliper or faulty brake line on the right
• I've got it shifting 1->2 at about 12-14mph and 2->3 at about 30-32mph. Shifts are firm.
  • ^That's with the vacuum regulator swiveled as far as it will go towards the radiator.
  • Paying closer attention today, with the vacuum regulator swiveled as far as it would go in the other direction (towards the firewall), it was shifting at about 8-10 & 20-22.
  • For reference, with a new regulator and modulator, my unit currently offers adjustable shift points ranging from approximately:
    • 9mph to 13mph for shifting from 1st->2nd
    • 21mpg to 31mph for shifting from 2nd->3rd
  • That range is tighter than I expected, as I'm not able to get the points up to 15 and 35 like some have suggested (granted it was meeting/exceeding those values before replacing the modulator, though was also not responding to regulator adjustments)
    • thus I am thinking something still isn't quite right
      • maybe some of that crud that I saw in the modulator got sucked up into the vacuum hard line and is impeding suction...
        • will check the vacuum pressure at all points down the line once again to make sure the readings aren't off, but I'm considering just replacing the hard line (since I've seen so many other posts from folks on this site who did that and it solved their shifting problems)
      • though with my current shift points at ~13mph & 31mph, I'm tempted to just leave well enough alone.... but a small part of me is worried that whatever little gremlin is still there will fester and end up expediting wear on the transmission.... what would @cucvrus do?

Shift points are going to vary depending on your driving habits. Quick acceleration or slow acceleration will change your shift points. Sounds like you are in the right range. The cheaper modulators I'm not a fan of. I like the best modulator you can afford. Also, I'm not a fan of the adjustable ones, that's just me. The vacuum pump pods are available on Amazon for a reasonable price if you think your vacuum pump isn't performing properly. You don't need 15-35 shifts, 13-31 seem good enough. No stress.

 

[Zeb]

Shift points are going to vary depending on your driving habits. Quick acceleration or slow acceleration will change your shift points. Sounds like you are in the right range. The cheaper modulators I'm not a fan of. I like the best modulator you can afford. Also, I'm not a fan of the adjustable ones, that's just me. The vacuum pump pods are available on Amazon for a reasonable price if you think your vacuum pump isn't performing properly. You don't need 15-35 shifts, 13-31 seem good enough. No stress.

Thanks, that’s a relief to hear. I’ll be glad to move on to the next CUCV project and leave the transmission stuff alone for a while. Do you have a specific modulator you recommend? I didnt put much thought into it, and went with the Pro-King Automatic Transmission Vacuum Modulator, Part # MD-48 for $16 at Advanced. If it’s worth the trouble, I’ll put a better one on and just keep the $16 one as a backup

 

[ezgn]

Thanks, that’s a relief to hear. I’ll be glad to move on to the next CUCV project and leave the transmission stuff alone for a while. Do you have a specific modulator you recommend? I didnt put much thought into it, and went with the Pro-King Automatic Transmission Vacuum Modulator, Part # MD-48 for $16 at Advanced. If it’s worth the trouble, I’ll put a better one on and just keep the $16 one as a backup

I'll check it out for you. Yeah, I think I would do the same thing.

 

[ezgn]

Thanks, that’s a relief to hear. I’ll be glad to move on to the next CUCV project and leave the transmission stuff alone for a while. Do you have a specific modulator you recommend? I didnt put much thought into it, and went with the Pro-King Automatic Transmission Vacuum Modulator, Part # MD-48 for $16 at Advanced. If it’s worth the trouble, I’ll put a better one on and just keep the $16 one as a backup

Amazon has a B&M adjustable modulator for $37.96 #20234 pre-set for factory specs. with fine adjustment point for 2-4 mph at the modulator. They have other ones listed under 1984 k-30 6.2 diesel, check out the better ones.

 

[cucvrus]

OK. You ask for my opinion. I was a GM Service technician back in the late 70's and early 80's. I was not the transmission guy. The dealership I worked in we had guys that did transmissions and we had guys like me that did general service work, warranty and factory recalls. I did Pennsylvania state inspections also. Very few mechanics in the shop were a do all technician. Thus I learned to take certain items to qualified people. Transmissions being one of them. I had a transmission guy that did all my transmission adjustments and transmission work for 35 years. I saved money and took the guesswork out of the equation. Saving money sometimes involves spending money up front. I also found that doing it right the first time has a slight sting but the sting goes away long before the issue arises again. I do and did a lot of preventative maintenance in my lifetime. To my own stuff. I had alternators, starters, transmissions and engines gone over before they failed. It has always worked out. And I recall few times walking home or away from a stranded vehicle while being used for the intended use. I had a few failures off road and under extreme conditions. A few. But that was not the norm. Get the transmission to a reputable shop and have it checked and adjusted by someone you trust or a friend recommends. Then drive on. Sometimes the diagnosis is not what you want to hear but if it is what it is you can decide from there. I think the TH400 is the best transmission for the CUCV. That is my opinion. And hundreds of thousands of miles have proven that to me. Good Luck and Be Safe.

 

[ezgn]

Personally, I would junk that cheap modulator and replace it with the B&M quality modulator. Getting your transmission checked out would be the best alternative, but for my choice, even after getting it checked out, I would junk the cheap modulator.

 

[Zeb]

OK. You ask for my opinion. I was a GM Service technician back in the late 70's and early 80's. I was not the transmission guy. The dealership I worked in we had guys that did transmissions and we had guys like me that did general service work, warranty and factory recalls. I did Pennsylvania state inspections also. Very few mechanics in the shop were a do all technician. Thus I learned to take certain items to qualified people. Transmissions being one of them. I had a transmission guy that did all my transmission adjustments and transmission work for 35 years. I saved money and took the guesswork out of the equation. Saving money sometimes involves spending money up front. I also found that doing it right the first time has a slight sting but the sting goes away long before the issue arises again. I do and did a lot of preventative maintenance in my lifetime. To my own stuff. I had alternators, starters, transmissions and engines gone over before they failed. It has always worked out. And I recall few times walking home or away from a stranded vehicle while being used for the intended use. I had a few failures off road and under extreme conditions. A few. But that was not the norm. Get the transmission to a reputable shop and have it checked and adjusted by someone you trust or a friend recommends. Then drive on. Sometimes the diagnosis is not what you want to hear but if it is what it is you can decide from there. I think the TH400 is the best transmission for the CUCV. That is my opinion. And hundreds of thousands of miles have proven that to me. Good Luck and Be Safe.

Sometimes the best advice is what you'd rather not hear. But I plan to get this m1008 running reliably well ASAP, and keep it running well for as long as I'm able to drive (hopefully at least another 60yrs). So I'll take your advice, and have the TH400 inspected by a trustworthy transmission shop in the near future (before the m1008 moves the farm in July, but after I get these other components replaced... will probably get it looked at in Feb/March).

Personally, I would junk that cheap modulator and replace it with the B&M quality modulator. Getting your transmission checked out would be the best alternative, but for my choice, even after getting it checked out, I would junk the cheap modulator.

Just placed an order for the B&M #20234 modulator. I have a hard time junking anything...even junk... so I'll probably list it on eBay for $5 before I throw it in the metal scrap pile. Thanks for the suggestion on which modulator to get!

 

[Zeb]

Swapped the cheap vacuum modulator out for the recommended B&M #20234 modulator over the weekend. Small, but noticeable, difference in shifting. Now reliably shifting 1->2 at 15mph (with exception of first shift after cranking, which is closer to 20) and 2->3 at 30 (also with exception of first shift after cranking, which is closer to 35). That about exactly where I wanted my shift points, so thanks @ezgn for the recommendation!

Also replaced the tie rod(s) and kingpin bushings/springs. Steering is MUCH tighter. Almost no drift in the steering wheel now, and haven't experienced even a hint of death wobble since replacing the drag links. Very happy with these results. However, the truck still has a mild shake at speeds around 40-55mph, pulls right if I let go of the steering wheel at speed, and still pulling hard to the left when I brake.

Had the front end aligned yesterday at a local shop.... guy said I wasn't far off on the tie-rod spacing when I brought it in, but they did have to do some adjusting. No noticeable improvement in shake, veering right at speed, or veering left while braking after he was through with it. Said HE thinks the veering left while braking has something to do with the suspension...maybe a loose component?
I was leaning towards something with the brakes....but when I checked over the weekend both front calipers appear to be depressing equally and the lines appear intact. I remember hearing a loud pop/snap on the front right side of the truck less than a minute before the leftward braking started... maybe that was something with the suspension...didn't notice anything other than the injured drag link (located front left of truck) when I looked at that time, but will more closely inspect the suspension as soon as I can. Thinking maybe a tire balance will help some with high speed shake, but not expecting that to improve leftward/rightward pull.

I did give drag-link adjustment a shot to help with steering wheel alignment (has been cock-eyed to the left since I hit a BIG hole last year), and had the alignment shop try to center the steering wheel as well.... but not much improvement seen by either of our efforts. Seems like after getting it centered, it returns to leftward lean after hitting the brakes.

 

[cucvrus]

Did you check the outer axle U joints? Is one of them bound up. I had it happen several times. Good Luck.

 

[Zeb]

Had the tires balanced a few days ago, and high speed shake improved a little bit... but shop manager said all 4 tires are out of round, so figure residual shake could be from that... but the shake isn't consistent....so thinking it may be something other than tire balance or front end alignment issue...

Did you check the outer axle U joints? Is one of them bound up. I had it happen several times. Good Luck.

Yes, but maybe not to the degree I should have... Visually they look good, no cracks or warping noted. They feel tight/firm (by hand, with the truck sitting on the ground). None of the nuts appear to have backed off or loosened (didn't take wrench to them though).
....should I jack the front end up and check for loose Ubolts with weight off of the springs? Or is inspecting on the ground sufficient?

Given the intermittent shaking at high speeds and persistent leftward braking, on top of a sagging front suspension (relative to the back), I'm considering replacing the front lift springs, shocks, ubolts, and bushings.

 

[cucvrus]

Had the tires balanced a few days ago, and high speed shake improved a little bit... but shop manager said all 4 tires are out of round, so figure residual shake could be from that... but the shake isn't consistent....so thinking it may be something other than tire balance or front end alignment issue...



Yes, but maybe not to the degree I should have... Visually they look good, no cracks or warping noted. They feel tight/firm (by hand, with the truck sitting on the ground). None of the nuts appear to have backed off or loosened (didn't take wrench to them though).
....should I jack the front end up and check for loose Ubolts with weight off of the springs? Or is inspecting on the ground sufficient?

Given the intermittent shaking at high speeds and persistent leftward braking, on top of a sagging front suspension (relative to the back), I'm considering replacing the front lift springs, shocks, ubolts, and bushings.

I am referring to the outer axle U joints. They can become tight and not return to the straight-ahead neutral position on one side and make all sorts of things happen. I had them front axle U joints bad on a 1984 M1028 and the 1984 M1028 had a different rear cab crossmember. It had just cab perches on each frame rail and was connected with a small piece of steel angle. My U joints were so tight I could steer but it would continue to go in the direction I was going and then I would force it back and it would over steer. I heard a cracking sound every time this happened and discovered the noise was coming from that small rear cab mount angle. I jacked up the front end and I could not steer the truck with the engine off. The power steering was whining when I was on the road. Long story short I would jack up the front end and steer stop to stop with it manually with the engine not running. Report back. Also check the slides on the calipers and make sure they are clean and greased. Both the calipers and the knuckle slides. Grease, not spray lube. Good Luck.

 

[Zeb]

View attachment 857108
I am referring to the outer axle U joints. They can become tight and not return to the straight-ahead neutral position on one side and make all sorts of things happen. I had them front axle U joints bad on a 1984 M1028 and the 1984 M1028 had a different rear cab crossmember. It had just cab perches on each frame rail and was connected with a small piece of steel angle. My U joints were so tight I could steer but it would continue to go in the direction I was going and then I would force it back and it would over steer. I heard a cracking sound every time this happened and discovered the noise was coming from that small rear cab mount angle. I jacked up the front end and I could not steer the truck with the engine off. The power steering was whining when I was on the road. Long story short I would jack up the front end and steer stop to stop with it manually with the engine not running. Report back. Also check the slides on the calipers and make sure they are clean and greased. Both the calipers and the knuckle slides. Grease, not spray lube. Good Luck.

Sorry, misread your previous post. Thanks for clarifying, and explaining how to check these! I'll check em this weekend.

 

[Zeb]

Did you check the outer axle U joints? Is one of them bound up. I had it happen several times. Good Luck.

Just had all 7 Ujoints replaced:
-high-speed shake has almost completely resolved (I assume the little bit left is due to out-of-round tires)
-the leftward pull while braking has not improved at all

Also, since picking the truck up, there is more steering wheel wander when turning against higher resistance (e.g. at low speeds, making sharp turns, or turning while braking). When turning against low resistance (e.g. changing lanes at high speeds) there is almost no play/wander.

In the last few months I've replaced the king pin springs & bushings, the drag links, tie rods, steering stabilizer, and Ujoints.

So I'm thinking the problem has to be with the steering box (play in the output shaft, or maybe internally?) or pitman arm (prior owner installed a drop pitman arm for the 6" lift, and I had to retighten the bolt holding it to the steering box output shaft last month... maybe it's loosened up again). Plan to inspect these today by having somebody turn the steering wheel while I'm outside of the truck watching the pitman to box connection. Any other tips on how to rule out a problem with these components? Or any other thoughts on what else might be causing the leftward braking issue?

*Update a few hours later:
After observing the steering gear box and pitman arm while my wife turned the steering wheel:
-arm appears tight
-output shaft moves vertically up and down about 1/2" at start of turns
-input/steering shaft appears to spin quite a lot more than I would expect before I see output shaft response

Think I will replace the steering gear box and go from there

 

[ezgn]

Just had all 7 Ujoints replaced:
-high-speed shake has almost completely resolved (I assume the little bit left is due to out-of-round tires)
-the leftward pull while braking has not improved at all

Also, since picking the truck up, there is more steering wheel wander when turning against higher resistance (e.g. at low speeds, making sharp turns, or turning while braking). When turning against low resistance (e.g. changing lanes at high speeds) there is almost no play/wander.

In the last few months I've replaced the king pin springs & bushings, the drag links, tie rods, steering stabilizer, and Ujoints.

So I'm thinking the problem has to be with the steering box (play in the output shaft, or maybe internally?) or pitman arm (prior owner installed a drop pitman arm for the 6" lift, and I had to retighten the bolt holding it to the steering box output shaft last month... maybe it's loosened up again). Plan to inspect these today by having somebody turn the steering wheel while I'm outside of the truck watching the pitman to box connection. Any other tips on how to rule out a problem with these components? Or any other thoughts on what else might be causing the leftward braking issue?

*Update a few hours later:
After observing the steering gear box and pitman arm while my wife turned the steering wheel:
-arm appears tight
-output shaft moves vertically up and down about 1/2" at start of turns
-input/steering shaft appears to spin quite a lot more than I would expect before I see output shaft response

Think I will replace the steering gear box and go from there

Can you distinguish if the actual brakes are pulling from the rear or the front or both? Or does it feel more like a suspension problem? Have you had the brakes exposed to inspect any problems? Are the rear brakes stopping evenly when you hit the brakes real hard, or is one side locking up? Are all of your spring bushings in good shape? Are your U-bolts all tightened down evenly with the proper torque? Are your shocks all working properly?

 

[cucvrus]

Have you had the front end alignment checked on a machine that has a qualified operator? No tape measure alignment and guessing. These issues are hard to resolve with things being misaligned, out of round or unbalanced tires. Adding a lift kit and other questionable suspension modifications just makes diagnosis more of a problem. Good Luck. Be Safe.

 

[Zeb]

Problems solved! ...for now *knock on wood*

Turns out there were multiple issues leading to my steering/braking problems:

• replaced the steering gear box with a reman from AAP -> no change whatsoever.... the original gear box was obviously working just fine, so I'm holding on to it just in case this reman doesn't work out (found mixed reviews about these remans in the SS threads)
  • of note, I also attempted to replace the steering coupling assembly while I was in there, but failed due to the part I ordered not fitting. So heads up, the Dorman Steering Coupling Assembly sold by AAP (PN 31011) does NOT fit despite the AAP website saying it will fit a 1985 K30
• after replacing the gear box, I had my wife jump back in the driver seat and turn the wheel while parked -> realized the front driver side leaf springs were sliding back and forth on the front axle a good 5-6" each direction as the steering wheel was turned lock to lock!!!
  • I centered the springs and tightened the u bolts down (they were terrifyingly loose) -> immediately solved the problem of steering wheel resetting it's center while driving/turning
  • I am appalled that my dumb*** missed such a simple and dangerous issue for this long. And am so thankful that I didn't lose control of steering and wreck or kill somebody. I'm almost second-guessing my qualification to own/drive/work on a CUCV at this point, as that awful oversight could have had serious consequences.... Just gonna have to be more thorough/careful in the future. Lesson learned
• after all of that, I finally got around to replacing both front brake calipers -> leftward braking solved
• lastly, replaced the old out-of-round tires -> rides almost smooth at high speed now

Finally feel like I'm at a point now with my CUCV that I can take a breath and enjoy it again! Hopefully this honeymoon period lasts long enough for my bank account to recover.

 

[Zeb]

Have you had the front end alignment checked on a machine that has a qualified operator? No tape measure alignment and guessing. These issues are hard to resolve with things being misaligned, out of round or unbalanced tires. Adding a lift kit and other questionable suspension modifications just makes diagnosis more of a problem. Good Luck. Be Safe.

I did have an alignment done by a backwoods mom/pop shop recently, but to be sure I'm taking it into town today to a place with a machine operated by a qualified individual. I prefer the backwoods most of the time, but will be in the city today anyways and figure after getting everything else taken care of I should get this redone too.