1939 Buick Special lower control arm bushings

[Guest joetunick]

With regards to the lower front control arm bushings, the 1939 Buick manual shows two bushing types: a rubber bushing and a brass bushing (supposedly with grease fitting). I have the brass bushing but without a grease fitting. The manual alludes to removing the rivets holding the control arm together in order to access the shaft and bushings. Is this the only way? I bought a kit from Kanter, which uses the later multi-piece design. Since I'll no longer need the old shafts (and they're beat anyway) I guess I can cut them out and not have to worry about the rivets. Does anyone have any experience they could share about this?

Many thanks,

joetunick

[danhar1960]

Joe,

What car are you working on and which bushings do you want to replace?? Is it a series 40 or 60 or a series 80 or 90.

There are no brass bushes on a series 40 or 60 but there is on a 80 and 90.

Given you say you have the brass bushing type, it sounds like you have a 80 or 90.

If you are replacing the lower inner bushes and shafts, rubber or steel, on all models, you will need to remove the rivets and replace them with some high tensile bolts.

If you are replacing the upper and/or lower outers then it is not necessary to remove the rivets.

Maybe a little more specific info on which model and which bushing and we can give a better answer.

Danny

[Guest joetunick]

Hi Danny,

It is definitely a 40 series. I have several '39 Buick Specials (mostly parts cars) and they all have brass bushings on the inner lower control arms where they attach to the frame. There is no mention of this in the manual, only rubber. I think the rubber ones were short lived and the fix was to rip them out and pound in brass ones from the outside as there is no evidence that the rivets have been replaced. However, in most applications they were fit too tightly, didn't use a grease fitting, and then wore out or froze up with time. My good '39 moaned and groaned with suspension movement. I've got the entire front end apart now (steering box was shot, too). The brass bushings were definitely the problem-You could barely move the control arm by hand.

What I have found is that the '39-'41 40 series used this set up. In early '42 they went to the threaded metal bushing set up but they used a shaft that had the same bolt spacing as the '39: 2 5/16". The bushings were the same as later '42 through '56-ish. Late '42 changed to the same set up as '46 and later 1 7/8" arm bolt spacing. But even if I could find this early '42, they won't fit the control arm since there are no provisions for the threaded bushing in the '39 control arm. If I could find a complete early '42 control arm I'd be set-but there's only a slim chance of that. So here's my plan. I will make new shafts and use polyurethane bushings with steel inserts. I will use the stock mounting brackets. If I design it correctly I will only have to cut out the old shafts, the new shafts should be able to slip on from the inside and the bushings will go in from the outside. I can tell you that it won't look stock so this isn't for 100 point show cars. Is anyone out there interested if I make these?

I took one control arm apart by removing two rivets. I'll use grade 8 hardware when I put it back together. Hopefully I won't have to take the other one apart.

Comments more than welcome!

Joe

Joe,

What car are you working on and which bushings do you want to replace?? Is it a series 40 or 60 or a series 80 or 90.

There are no brass bushes on a series 40 or 60 but there is on a 80 and 90.

Given you say you have the brass bushing type, it sounds like you have a 80 or 90.

If you are replacing the lower inner bushes and shafts, rubber or steel, on all models, you will need to remove the rivets and replace them with some high tensile bolts.

If you are replacing the upper and/or lower outers then it is not necessary to remove the rivets.

Maybe a little more specific info on which model and which bushing and we can give a better answer.

Danny

[danhar1960]

G'day Joe,

Never seen or heard of brass bushes in there before and it's definitely not right. It would be interesting to see a few picks of them.

I've wrecked 6 '39s and the some had the rubber bushes and some had the earlier/later type steel nuts.

You can get these from Bob's :

http://bobsautomobilia.com/shop/suspension-and-steering/lower-inner-aframe-shaft-1937-57-see-list-li-373.html

They should do the job for you. Check a set of your A frames as the arms may already have the thread for the nut type shafts.

My spares are a few hundred klms away to look.

I went original rubber but still had to remove the rivets to replace them. I'm trying to stay original (mostly . )

Buick obviously thought it wasn't a great idea as it was a 1 year only thing.

Let us know how it turns out.

Danny

[Guest joetunick]

Hi Danny,

Thank you for the link to Bob's Automobilia. He indeed does have the bushings. However, the shafts I have are in poor shape and must be replaced. If I had a set I may be tempted to use the rubber bushings but since I will have to make my own I may as well improvise.

Here's a few pictures. The large washer was used over the end of the bushing-I forgot to put it back in place for the photo. The bushing was definitely hammered in from the outside. The ID of the control arm is not threaded and measures about 1.309/1.310" ID. The widths vary from 0.984" to 1.009 ".

I have also attached a page from my 1946 Buick shop manual supplement to the '42. Figure 3-2 shows the shaft bolt spacing different between 1942 and 1946 with the '42 spacing being the same as the '39 (2 5/16"). It says that the threaded bushings are the same. This implies that the '42 arm was threaded. The '39 was not so the '42 shaft will not fit the arm although it will fit the chassis. Please note that Figure 3-1 is a little contradictory. It shows a fabric bushing not a threaded steel bushing. Maybe 1942 was a transition year.

You mentioned that you removed the rivets. I removed the heads of two of them and slide one side of the control arm out of the flanges. I thought I'd be able to push the rivets out but NO WAY! I'll have to drill them. How exacting were you when you removed yours? I plan to have the shafts in place on both ends prior to bolting them together so the alignment is right. Any suggestions?

All the best,

Joe

G'day Joe,

Never seen or heard of brass bushes in there before and it's definitely not right. It would be interesting to see a few picks of them.

I've wrecked 6 '39s and the some had the rubber bushes and some had the earlier/later type steel nuts.

You can get these from Bob's :

http://bobsautomobilia.com/shop/suspension-and-steering/lower-inner-aframe-shaft-1937-57-see-list-li-373.html

They should do the job for you. Check a set of your A frames as the arms may already have the thread for the nut type shafts.

My spares are a few hundred klms away to look.

I went original rubber but still had to remove the rivets to replace them. I'm trying to stay original (mostly . )

Buick obviously thought it wasn't a great idea as it was a 1 year only thing.

Let us know how it turns out.

Danny

[danhar1960]

Yes Joe, I had to drill the old rivets out and yes to assembling the shafts before bolting the spring saddles back on. Easy enough on the '39 with the rubber bushes. I've seen the reference to fabric bushes before. Not sure what that's all about. Probably were going to change to it but then thought better of it and just went back to the '38 style. The books were probably printed before they changed their minds in '40 and the mistake was never corrected. (sounds like a good theory anyway :) ) It wouldn't be the only thing wrong in the manuals.

I did my '38 lower inner "A" frame shaft with metal bushes which is the same as the later type.

I recorded the distance from the inside of the arm to the centre of the bolt, screwed the bushes into the arms, then screwed the shaft into one side bush, then wound the other arm around on the shaft until it was the right distance. Both sides should be reasonably even. It wasn't perfect but close enough. I think the page above may even gives some dimensions (too small to read). Too far one way or the other and the shaft wont rotate.

Just make sure that the measurements between the arms at the outer end are close to what the were. There is a little latitude there but the closer the better. The bolt holes in the spring saddles and arms should be reasonably close to lining up if all is well although they may need a little opening up. Just make sure the bushes don't bind on the shaft.

The real fun part is finding someone competent enough to do a good wheel alignment on it when you're finished. The majority of people these days wouldn't have a clue on how to do it on one of these old beasties. You'll probably have to take along the workshop manual for him. Adjusting the upper outers is a trap for young players. I bought the old time stuff on Ebay and do it myself.

Hope it all works out.

Danny

Edited March 16, 2014 by danhar1960 (see edit history)

[trp3141592]

Hi,

I may have to make some suspension parts also, so I am curious about the material you will use for the shafts. I can turn the shafts easily enough, but I don;t know squat about the steel to be used. My guess is that the shafts have to be hardened, which I can have done locally. Do you have a spec for the type of steel to be used?

Thanks,

--Tom

[Guest joetunick]

Hi Tom,

For once I can be useful since I'm a metallurgist! In fact, just moments ago I measured the hardness of the shaft that I need to make. The hardness of the OE 1939 Buick shaft in the bushing section was RB (Rockwell 100. This value is slightly above the normal RB scale but it was also below the minimum hardness for RC scale. In any event, this puts the shaft around the hardness of a Grade 5 bolt: tensile strength in the vicinity of 100 ksi. Incidentally, a grade 3 (cheap) bolt I had sitting there had a hardness of RB 72, which puts us in the vicinity of 60 ksi in tensile strength. I had an old grade 8 bolt that came in at RC 33 or about 150 KSI while new grade 8 bolts came in at 28 RC or 130 ksi. In any event, the shaft does not need to be made out of anything really outrageous. A run of the mill 1035 or 1040 steel will do. If you want to get exotic a 4140/4142 steel in the hot rolled form will do. In any case you won't have to heat treat it. Do not use anything with an "L" in it. These contain lead for easy machining but are bad for suspension components or anything in any cyclic or fatigue environment. Sometime ago someone was selling steering balls (for drag links, etc.) made of 12L14 and they were failing in the shaft under the ball head. Very bad.

INCIDENTALLY, I happen to have some of the shafts for the threaded end type. A 1950's replacement shaft had a hardness of RC 50! This was probably made of 1040 steel that was heat treated. However, a new replacement shaft sold by many has a hardness of RB 96. I'm a little surprised. I'm sure it won't break but it probably won't last as long as the original. I think the replacement parts companies justify this because the cars won't see 100,000 miles after being restored.

My dilemma at this point is how to make the shaft for the '39. The '39 shaft is held in by two stamped brackets that slip onto the shaft and hold it in place at a shoulder on the shaft. It is clear that this allows some axial movement in the shaft as the brackets were deformed. I would also like to design a system that can be installed without taking apart the control arm. This kind of implies that the brackets slip on over the side of the shaft rather than over the ends of the shaft. I.e., the brackets would not be captive to the control arm. As for the bushing my R&D effort (Rip off and Duplicate) tells me that the bushing design used by Global West is pretty good. I'll use nylon 6/12/or 6/6. They will go in from the outside.They will be a press fit into the control arm with a radial hole to line up with a zerk fitting to be installed in the arm end. I'll put some spiral groves on the ID for greasing. It will be flanged but I'll use a large flat washer and a castle nut and cotter pin. There really isn't anything going on on the inside part of the bushing but I may use a thrust washer just the same.

I'll report when I come up with a decent design. In the meantime, if anyone has any ideas please share them.

Regards,

Joe

Hi,

I may have to make some suspension parts also, so I am curious about the material you will use for the shafts. I can turn the shafts easily enough, but I don;t know squat about the steel to be used. My guess is that the shafts have to be hardened, which I can have done locally. Do you have a spec for the type of steel to be used?

Thanks,

--Tom

[trp3141592]

Hi Joe,

THANK YOU for this information!! I'll make the parts I need with confidence.

Thank you again!

--Tom

[Guest joetunick]

Tom,

Are you planning on duplicating the original shaft? It's not a trivial cross section. There's a large flat for registering on the frame. There are shoulders for the brackets to locate and fix the shaft. The brackets mate with the radius opposite the flat. If you're planning on using the original brackets then you'll have to duplicate the cross section of the shaft entirely; not impossible but not trivial.

My plans are to come up with a system that can be installed without taking the control arm apart. This means a new bracket system. I'm working on it... slowly.

Joe

Hi Joe,

THANK YOU for this information!! I'll make the parts I need with confidence.

Thank you again!

--Tom

[Guest joetunick]

Okay, folks, here's an important update:

I was talking to Glen at RareParts. They make a lower control arm shaft for the '40 series 40 (and same # through 1942) that has the same bracket spacing as the '39. It's part # RP15419 and it uses the threaded trunnion ends. This WILL NOT FIT cars that originally came with the rubber or fabric bushings because there are no threads in the inner ends of the control arm. However, RareParts also makes a complete lower control arm for the '40 that has threaded bores (part # RP15440). I'm pretty darn sure that this will fit the '39. So, the fast fix is to purchase the shafts and control arms. They have a clever control arm design. It looks almost like stock except that it will fit either side since the stamping for the stabilizer bar attachment extends in both directions.

Also, in an early post I mentioned that I had two shafts for the threaded trunnion end design. The new replacement was very soft and the old replacement was Rc 50. Glen tells me that the replacement parts made at RareParts are heat treated to higher hardness than the new replacement ones I have.

[Guest joetunick]

Finally, it's all done!  Here's the bottom line: There were no screw/threaded bushings used on the 1939 Buick Special lower control arms. Cars that have them are not made with left over '38's as those parts won't bolt on since the shafts have a different bolt spacing. Rather, someone replaced the control arms with later units. '39-'42 used the same spacing of 2 5/16" x 8.5" (center to center). However, 40 and later used the screw bushings. Therefore, if one could get the control arms from a 40-42 Buick we'd be set. And replacement parts are still being made, which I find really surprising.

The parts I used were made by Rare Parts. I can't thank them enough for all the time they spent trying to figure out how to convert my '39. And then, they tell you to buy them from www.carpartsdiscount.com since they are one of their largest customers. The parts I used:

Lower control arm: RP 15440

Lower control arm shaft: RP15419

The original control arms are specific to side since the sway bar link only bolts to one side. The replacement has a flange that allows the control arms to be switched side-to-side.

I did a very comprehensive rebuild: every part was replaced or rebuilt. I put some aftermarket springs that were slightly stiffer (10% or so). The front end is incredibly smooth and the car doesn't sound like a rusty screen door as it goes over bumps.