K member swap and upgrades. Bergman pins

clementine

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Hellooooo FABO!
I am going through the process of swapping my 67 year only K frame for the later with the updated idler arm mount. My question is....

Where the LCA pivots fit through the K member. How tight is that supposed to be? I got the Bergman jobbies with the delrin bushings and adjustable struts and am boxing in the LCAs. With a bunch of gusseting around the steering box mount area, along with a new PST 20:1 box Im hoping to make this thing steer nice.

You will see on the drivers side the pin does not go all the way in but will probably with final torque. the drinkers side is a bit more loose. Also, I have room for putting washers on both sides given there is a bit of shank still showing even with washer on.

Not sure how to attach vid. But it wobbles about 1/6" in the hole translating to 1/8" at the delrin end of pin

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Not sure why it double posted pics #generationX

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go-fish

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My Bergman Delrin bushing pins have the same situation. It is just on a K-frame dolly and was hoping the slop would go away when it has the weight of the car on it. I’ll be watching this thread.
 

clementine

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I would just put a couple tight fitting washers welded fore and aft, but having a bit of movement in the pin, who knows exactly where to put it? I welded a washer to the last Kmember, on the torsion bar side trying to clean up some slop and ended up have a TB that did not want to go in. Upon disassembly, the pin was bent. I have not drove the car so it may have been installer error if the pin was already bent. I am just looking to not repeat mistakes.
 

74 360 dart sport

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Well I just installed these with delrin bushings from Peter Bergman but do not I repeat do not torque to the specs specifically told to me by peter he said 145 to 150ft.lbs of torque the shop did this and pulled the pin through the fing k member not pulled thru but enough to make a perfect crack in the shape of the pin I called Peter and I had him on speaker phone told him what happened and he said that's not possible he said most shops can't get them that tight because they will start to spin if we get them to 105ft.lbs is good enough I then sent him pictures of the k member he told me that he could tell someone had did a really hairy messed up welding on the k member we thought the same after looking at it but after I finally found another k member and my old 1 was taken out it was not previously welded it was from when I brushed on por 15 and it had ran and looked like a bunch of hairy stuff so do not torque to his specs torque to 120ft.lbs and everything will tighten up 3000 dollars later on me will save you the same headache
 

72bluNblu

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The LCA pins should not wobble around in the sleeves in the K frame, they should be tight.

And if 150 ft/lbs of torque cracked the K frame or the pivot tube then you needed to repair that K frame anyway, they should easily withstand that amount of torque if they’re in good shape and not damaged. That said, I reinforce the pivot tubes on my K frames as part of seam welding and gusseting the K frame.

D01BD0C4-57A8-49B3-B82D-C3ABAEAFF592.jpeg
 

clementine

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@BergmanAutoCraft

The LCA pins should not wobble around in the sleeves in the K frame, they should be tight.

And if 150 ft/lbs of torque cracked the K frame or the pivot tube then you needed to repair that K frame anyway, they should easily withstand that amount of torque if they’re in good shape and not damaged. That said, I reinforce the pivot tubes on my K frames as part of seam welding and gusseting the K frame.

View attachment 1715972917

Did you make plates? front and rear? Looks to be 1/8" thick? Then how did you locate the front of the car gusset? (nut side) I ask because that is the side that will have the most travel. Thank you for chiming in Sir.
 

72bluNblu

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The first K I did I bought Firm Feels gusset kit, the second K I just made everything myself. The LCA pivot tube gussets are on the rear only, I actually used a heavy duty washer from the hardware store when I made that particular gusset. I think it was like a 1-1/8” washer? I just sized it so it fit around the outside of the pivot tube and then cut the washer to be even with the top of the K.

On the front side the pivot tube is welded to the inside of the K and the tube doesn’t protrude out. I know @Jim Lusk opens the K and welds those from the backside. I did not do that on mine, on a clean K you can see where the factory welds are, I drilled a couple holes through the K to the tube and did plug welds on the front.

If the pivot pin fits tightly at the back of the tube the side with the LCA should carry the majority of the load. And with that side welded solid the front shouldn’t go anywhere
 

clementine

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If the pivot pin fits tightly at the back of the tube
If i have play on the LCA side, what do you suggest? I have seen folks run weld around here, but I left it until I got my pivots. Now that I have them (the pivots) I know they are a smidge longer and I have a little length to play with. I did make a mistake by welding on the LCA side previously and am a little shy to mess with it (LCA side) but I am open to suggestion. the driver side is tight.....the drinkers side has 1/32"+ of play...on the LCA side. Also, when welding the front side washer on there, how did you locate it to be center? I feel like putting the whole deal together and in the car with the torsion bar in place I could make sure it was easy in/out?

Thanks for the help.

EDIT: I see you have welded the LCA side in your pic. so front and back ....correct? wait, I re read the post....just on the back side. copy that. I wont change my post as it may add light to the situation.
 

Syleng1

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Don’t forget the the washer welded in is a great idea to fix an oblongs hole BUT it will affect caster. Sadly it is a great fix to save a worn out k frame.
 

go-fish

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When you get the weight of the car on them can you tighten them up further? Mine are at a point where they only tightened so much and the pins just spin in the Delrin.
 

clementine

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When you get the weight of the car on them can you tighten them up further? Mine are at a point where they only tightened so much and the pins just spin in the Delrin.
Haven't gotten to point of install.....It will be a week based on my upcoming schedule
 

72bluNblu

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If i have play on the LCA side, what do you suggest? I have seen folks run weld around here, but I left it until I got my pivots. Now that I have them (the pivots) I know they are a smidge longer and I have a little length to play with. I did make a mistake by welding on the LCA side previously and am a little shy to mess with it (LCA side) but I am open to suggestion. the driver side is tight.....the drinkers side has 1/32"+ of play...on the LCA side. Also, when welding the front side washer on there, how did you locate it to be center? I feel like putting the whole deal together and in the car with the torsion bar in place I could make sure it was easy in/out?

Thanks for the help.

EDIT: I see you have welded the LCA side in your pic. so front and back ....correct? wait, I re read the post....just on the back side. copy that. I wont change my post as it may add light to the situation.

When you inspect the pivot tube is there a place that is clearly worn or out of round? If there is then you can weld that area to add material. But you’ll have to either file it back to round (difficult to do accurately) or have it machined.

Your other option would be to replace the whole tube, but, you’d need a tube with the correct inner diameter which also might require machining to make it that way.

I’ve been fortunate not to have to do this repair yet, I wonder if @Jim Lusk has any other tricks or suggestions

When you get the weight of the car on them can you tighten them up further? Mine are at a point where they only tightened so much and the pins just spin in the Delrin.

You have to hold the pin from the backside to get them torqued properly, I honestly don’t think setting the car on its wheels will help the spinning situation since the bushings rotate on the pins when everything is assembled.

And I’m not sure you’re going to get the result you need anyway, if the shoulder of the pin is sitting flush against the pivot tube it’s not going to move any further to eliminate play. And you should be able to see that when you slide the pins in. Now, if there’s still a gap between the pivot shoulder and the tube it might tighten up a little more when the nut pulls the pin all the way forward

Don’t forget the the washer welded in is a great idea to fix an oblongs hole BUT it will affect caster. Sadly it is a great fix to save a worn out k frame.

It should not effect caster, the LCA bushing should still sit against the original pivot tube shoulder. The weld should go around the outside of the tube and not effect the mating surface.
 

74 360 dart sport

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The LCA pins should not wobble around in the sleeves in the K frame, they should be tight.

And if 150 ft/lbs of torque cracked the K frame or the pivot tube then you needed to repair that K frame anyway, they should easily withstand that amount of torque if they’re in good shape and not damaged. That said, I reinforce the pivot tubes on my K frames as part of seam welding and gusseting the K frame.

View attachment 1715972917
I find your comment funny there were no issues with the k member you state there must have been a issue prior and they should withstand 150ft lbs then why are you beefing yours up if it will withstand that
 

72bluNblu

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I find your comment funny there were no issues with the k member you state there must have been a issue prior and they should withstand 150ft lbs then why are you beefing yours up if it will withstand that

Simple, I didn't gusset the LCA pivot tubes to withstand the torque applied to the pins.

The entire corner weight of the car is supported by two things on a torsion bar car - the LCA pivot pin in the K frame and the torsion bar anchor in the transmission crossmember. The corner weight on these cars is in the range of 800 lbs give or take a bit, which means that just sitting on the suspension the LCA pivot (and therefore the K frame and pivot tube) is probably holding ~400 lbs of force. And that's before the suspension moves.

On a car with factory torsion bars, the wheel rate is about 100 lbs/in, with about 2.5" of compression travel possible, so, add another 250 lbs to split between the LCA and the anchor. On MY car, with 300 lb/in bars and the same 2.5" of compression travel, add another 700 lbs of force to split between the two. And of course if the suspension bottoms out more force than that can be applied in both cases.

So, yeah, the torque on the pins only applies a minimal load to the K frame compared to what it has to carry with the suspension loads. So if a 150 ft/lb torque caused the pivot tube/K frame to crack, well, it's probably a good thing it happened then because it probably would have failed later anyway when the suspension was loaded. Or worse, when someone was out driving.

And the wildcard is the factory welding, which was all over for quality. Some K frames have really terrible factory welding, so, those welds can crack if they weren't done properly. If everything is in good condition then the 150 ft/lb torque shouldn't be an issue. But not all 50+ year old K frames are in good condition, so they need to be checked. And if you build your car with better tires and stiffer suspension than the factory did, well, you should plan on having more force exerted on the K frame and torsion bar crossmember than the factory did. So gusseting the K frame is just good practice IMHO. Either way, if a 150 ft/lb torque cracked the welds, the pivot tube or the K member, well, it needed repair anyway, since it would never have withstood the suspension forces which will be much higher.
 

74 360 dart sport

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Simple, I didn't gusset the LCA pivot tubes to withstand the torque applied to the pins.

The entire corner weight of the car is supported by two things on a torsion bar car - the LCA pivot pin in the K frame and the torsion bar anchor in the transmission crossmember. The corner weight on these cars is in the range of 800 lbs give or take a bit, which means that just sitting on the suspension the LCA pivot (and therefore the K frame and pivot tube) is probably holding ~400 lbs of force. And that's before the suspension moves.

On a car with factory torsion bars, the wheel rate is about 100 lbs/in, with about 2.5" of compression travel possible, so, add another 250 lbs to split between the LCA and the anchor. On MY car, with 300 lb/in bars and the same 2.5" of compression travel, add another 700 lbs of force to split between the two. And of course if the suspension bottoms out more force than that can be applied in both cases.

So, yeah, the torque on the pins only applies a minimal load to the K frame compared to what it has to carry with the suspension loads. So if a 150 ft/lb torque caused the pivot tube/K frame to crack, well, it's probably a good thing it happened then because it probably would have failed later anyway when the suspension was loaded. Or worse, when someone was out driving.

And the wildcard is the factory welding, which was all over for quality. Some K frames have really terrible factory welding, so, those welds can crack if they weren't done properly. If everything is in good condition then the 150 ft/lb torque shouldn't be an issue. But not all 50+ year old K frames are in good condition, so they need to be checked. And if you build your car with better tires and stiffer suspension than the factory did, well, you should plan on having more force exerted on the K frame and torsion bar crossmember than the factory did. So gusseting the K frame is just good practice IMHO. Either way, if a 150 ft/lb torque cracked the welds, the pivot tube or the K member, well, it needed repair anyway, since it would never have withstood the suspension forces which will be much higher.
Thank you and I agree with your opinion
 

clementine

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alright alright alright....mocking up this small block K frame (67 barracuda 383 4 sp) with trans dapt 4698 mounts (sb K to BB) and its going pretty good, but I'm wondering if i need a different oil filter bracket? Or.....push engine forward a smidge...(only have 1/2" until fan pulley hits.) Or shim.... (was hoping to avoid major shimming, one of the reasons to try the swap from previous K)...or cutomize either the mount or the K member. If customizing the K/ mount is your choice, please include measures you would take to make sure engine is in car in the right spot (stick location, shifter rod location, Pittman, idler.... yknow stuff like that so i don't mis anything)

Thanks FABO

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