Front Axle / Front Suspension: Delrin Bushings

[Skybolt]

For those of you who have installed Delrin bushings in the control arms, lowers in particular, what spacers, if any were used to fill the gap between the end of the shaft and the outer face of the bushing?

I ask this because the original rubber/steel bushings use the inner steel sleeve to hold pressure against the shaft and the outer washer. As the Delrin bushings work in a slightly different way, they let the shaft turn freely inside the bushing, there is a gap, however, between the end of the shaft and the outer face of the bushing, which is usually taken up with some sort of spacer, bush, or standoff.

I have different sets of Delrin from different vendors and one set I procured, in a parts lot, was missing some spacers. I can make some quite easily from an old control arm shaft that has been bent from an accident and is no longer serviceable. After drilling the thread out and cutting small slices I can have as many as I wish.

The question is, that I was wondering, how other vendors package these bushings, with spacers, o-rings etc... and if they are of different materials and dimensions.

Any information would help before I cut the shaft incase there is an easier way or an off the shelf part.

I have no idea who the original manufacturer of the set of bushings I am currently working with so I can not go that route. All I ended up with was the Delrin and no other parts.

Len

[Alan]

Len, Without seeing the parts and checking against others I couldn't give you a good answer. I have a set from Collins in AZ. I use UHMW plastic on my cars and machine my own, but I build to each car and every bushing is different. I also tighten to feel and safety wire all bolts. I could make you new spacers if you need. I owe you a favor or 2 so let me know what you want to do.

[Skybolt]

Len, Without seeing the parts and checking against others I couldn't give you a good answer. I have a set from Collins in AZ. I use UHMW plastic on my cars and machine my own, but I build to each car and every bushing is different. I also tighten to feel and safety wire all bolts. I could make you new spacers if you need. I owe you a favor or 2 so let me know what you want to do.

I'm okay for spacers, as I mentioned I can make some from an old shaft. The other spacers I have for a different set are aluminum. Also I am making sure the arms have the specified 10 3/4" inside spread and setting the shaft as close to center as I can then measuring the leftover gap to the bushing outer face. This set has a bit of a gap between the inside bushing face and the heal of the machined part of the shaft. I did wonder if there was supposed to be a washer/spacer there to take up that slack, but it is not a concern if I can hold the shaft central with the spacers on the outside end. Though sometimes I wonder if that is a good idea.

Alan, when you safety wire the bolts for the control arm shafts what do you wire them to, the control-arm, and if so do you drill a hole somewhere? Do the bolts turn with the shaft, as I have seen with other non rubber bushings? Do you use an outer large washer, of sorts, to cover the outer bushing face and to keep the lube inside? Do you use an o-ring, as I have seen on some sets?

Len

[bezhawk]

No, the space is eliminated when you tighten the bolts. Even with rubber bushings, the space is there until you tighten the bolts. The control arm has a certain springy-ness and will deform enough for it to not be a concern. One would only need spacers IF the inner part of the bushing hits the shoulder of the shaft BEFORE the outside bolt is all the way tight.

[Skybolt]

No, the space is eliminated when you tighten the bolts. Even with rubber bushings, the space is there until you tighten the bolts. The control arm has a certain springy-ness and will deform enough for it to not be a concern.

Not possible to pull the arm in and still stay within the 10-3/4" space for spread with these bushings. The inner distance between the arm is 10-3/4". If I were to tighten the bolts enough to pull the outer of the bushing to the ends of the shaft it would pull it in too far, another 1/4". If this is not a concern then I will do it.

I'm basing the 10-3/4" if anyone knows it should be different please let me know.

Len

[Alan]

Yes, I drill a .045" hole in the a-arm lip and in the bolt head, but I am an old A&E mechanic and that is standard procedure.

[Skybolt]

I had a 1975 BMW 3.0 setup with all the suspension bolts done the same way. I often think about that on my Studes, can't be too safe. While I have everything out that sounds like a grand idea.

Len

[bezhawk]

Come to think of it, the rubber bushings do have an inner steel sleeve that bottoms out on the shoulder of the inner shaft. I presumed it also took up the space between the end of the shaft, and the end of the inner sleeve when the outer bolts were tightened. if not, then you are correct in that you don't want the delrin bushings to hit the shaft shoulder before the bolts are tight. Ideally they should be close to the same length without binding when tight, so it is free to rotate on the shaft. I get my Delrins from Chuck Collins, and never had a problem with them. Some GM bushings are close to Stude specs, but are just slightly different in length, and have serrations on the inner sleeve. Correct Studebaker rubber bushings do not nave these, and rely on proper torque of the outer bolts to keep them from rotating on the shaft.
You do not want stock rubber bushings to rotate on the shaft. The rubber takes all the suspension movement in a twisting force, not a rotational movement of the bushing on the shaft. Delrin bushings however DO rotate on the shaft.

[mbstude]

George Klutkowski sent me an email a minute ago.. Probably more info than anyone wanted, but here it is..

Looked at the forum for a minute and noticed something that needs correction...you can post it.. Thread on the Delrin A arm bushings..
I have installed a couple dozen sets... You can quote me if you want..

The bushings must use spacers or the control arms will be distorted and the whole mess won't move correctly. I use a couple lock washers or
small spacers on each end and it works fine. The original rubber bushings do NOT 'compress' the A arms as stated; the outer large washer bites into the toothed inner steel sleeve locking it on the shaft. The rubber 'edge' does compress..

BUT...that is why you must always final tighten the rubber bushings after the car is on the ground and bounced and couple times. The rubber bushings 'wind up' in use but must be 'unwound' when you tighten the center bolts. The Delrin bushings when assembled on the arms and shafts should be free enough to let the arm pivot. I check all of this with the A arm in a vise and get it all correct before the arm goes on the car. You (Matthew) have seen me do this many times. The bolts get torqued with the arm off the car in the vise. The Delrin bushings pivot on the shaft but are a light press fit in the arms. Some of the Delrin's I have been getting are not cut correctly and need touching up on a lathe on the outer diameter to fit the control arms correctly. They are too tight and pressing them in ( I knock them in with a large socket) will crush them too much and they won't pivot on the shaft. This is the same setup used on GM stuff for a long time and I have done hundreds of these. If you put this stuff together incorrectly your suspension will not work worth a poop.

If anyone has installed the Delrin's without spacers they need to correct that. The large washer supplied with the Delrin kit should be pretty much even with the end of the bushing when everything is assembled and torqued. It's also important that your shafts be in good shape and deburred as the bushing rides on the shaft. That is where the grease should be and why there are small grease channels cut in the bushings. The control arms should be deburred also so the bushings will go in without too much fuss. Since I chatter gun out the old ones, there is always a couple of dingers in there that need attention. I have yet to get a set of Delrin's that don't need the spacers even though I have bellyached to the supplier to correct this...

Sorry if this isn't a real 'technical' response with 'numbers' but I recon after 45 years of doing this stuff you know when it 'feels right'...<G>.... I could write a whole story on this.. this is the 'short' version.

[Skybolt]

Matthew,

What you posted is what I understand to be true. All the past sets of Delrin have allowed the shaft and outer large washer to rotate and the bushing to remain seated in the arm. They have also had an o-ring between the bushing and the outer large washer keep any grease in and keep dirt out, as the shaft/washer/bolt assembly have some clearance from the bushing. To accomplish this with the set I have I will have to make some spacers. With the gap it could be that a washer with a large enough hole might work.

Len

[Skybolt]

It does appear that Studebaker part number 167772 is the exact size I need for the spacer. It turns out that the main cap bolts use a washer that has a 1/2" id 7/8" od and is 1/8" thick. I have a quite a few spare so I'm good for the spacers/washers.

I still think the inside face of the bushing should centrally locate the shaft so I might have to remove the bushings and start again.

Len

[Skybolt]

Made some spacers for the inner gap between the shaft heal and the bushing inner face out of some drilled out washers. Will install this week and see how it all goes.

I also made a replica of the Kent-Moore J-2044 Upper and lower outer trunnion tool. I will post some pics when I have the last bolt. I made it from some 1" 1045 square steel bar stock. The two pivot plates came from scrap, the two bolts were in my stock of stainless hardware I had, but the last part was a 1/2"-20 x 1-5/8" bolt, I tried Studebaker part number 526765, upper control arm to frame bolt, from a parted out Stude but the shoulder of the bolt was not the same diameter as the threaded part so no go with cutting a thread on that. I will pick up an appropriate one tomorrow. All up I guess the Kent-Moore J-2044 replica will total about $20, not accounting for labor, so at today's prices and my time, priceless.

Len

[Skybolt]

Just another thought here because of the the Kent-Moore J-2044 tool. Has anyone welded a brace across the lower side of the outer upper A-arm, or the lower A-arm, to help prevent distortion? I have often placed some plate across the A-arms to see where I would make them more rigid, like boxing them in. Of course there is the added weight but the strength and lack of distortion might pay off later.

Just a thought.

Len

[Alan]

Some thing like this, Len?

[/URL]

Notice that there is a crack on the right side near the end of the plate. Here is a pic a little farther along.

[/URL]

[Skybolt]

Not quite Alan but I can see where you're going with that.

I was thinking more like boxing it in but still using the original parts. For instance, with the lower A-arm, were in your second photo it shows the sway bar slotted tab between the spring pocket and the inner shaft, using a 2" or 3" wide plate from one side to the other, basically bracing behind the spring. This would stop any, if there is in fact any, flex in the A-arm. Using angle in there would be even stronger but maybe not necessary.

I do recall at one time you, or someone else, posted similar photos when we were going over the front suspension. I still have a few idea about that and will continue later but for the time being I have to get this Lark back on the road.

Len