Olds rear axle housing/trailing arms question

Ive been thru the Olds/Pontiac rear axle tech section and my searches have come up empty on this one...
Im wondering if there are any differences between 1950-1955 Olds leaf spring and coil spring rearend housings.
The coil spring trailing arms that Ive seen clamp around the axle tubes and I have a later (1959-64) housing which has flat spots on the top and bottom of the axle tubes which I ***ume keep the housing from rotating in the arms. Can anyone tell me if the earlier coil spring housings have similar flat spots?
I recently picked up a pre 1956 Olds (or Pontiac) rear with no brackets and the axle tubes do not have these flats, so Im wondering if it’s a leaf spring housing?

Im in the process of restoring a Model A coupe that my late brother owned in 1967-1968. Unfortunately, all of the drivetrain (except the front axle) is long gone.
I remember my brother saying the car had a ’50 Olds rear end, but the guy I recently got the car from (he owned it since 1969 or 1970) says it was a buggy sprung ’55 Olds rear. When I blow up this old photo I can see the trailing arms, so Im pretty sure a coil spring housing/trailing arm setup was used.
If the trailing arms wont work with this housing, Im thinking Id be better off looking for an entire stock coil spring rear end ***embly.

 

Dave50 has a buggy sprung 32 with a 49-50 Olds rear, with modified early Olds trailing arms.

I have a buggy sprung 32 with a 55 Olds rear with 35/36 rear arms.

On a Model A, he could have gone either way I suppose. That car is pretty high in the back, but that still does not help tell what it had, and if it was buggy, exactly where he mounted the spring. (above or behind)

I could be wrong, but I doubt he could have put coils on top of the axle tubes, as I don't think there is enough room even though that car is high. If he did, by cutting the coils, it would ride like solid mount IMO

 

Aren't those "flat spots" nothing more than welded on pads? I would certainly think either rearend would work-just use or modify the pads to suit the app. Setting he coils on the arms will improve vertical spacing but, as somebody said: the arms will work with a transverse spring.a

 

plumbid...Ive been taking some photos as I go and will start a build thread soon. I wanted to have enough pics to keep the thread from lagging in spots since I work slow.

F&J...The previous owner is certain that it was a transverse spring and I have no intention of going coils, my concerns were the mounting points of the arms to the axle since I have nothing for reference. The car will be solid lifter SBC/stick shift like it was way back when, so '35-'36 bones scare me as I may get carried away once in a while. I hope to find a pair of Olds trailing arms locally, but if not, Ill probably have to buy them sight unseen so Id like to know the differences...ie, round axle tubes vs. flat ones.

Dale...there are definite formed flat spots on the later axle tubes, something that would be difficult to replicate on the earlier housing. Ill post a pic in a bit.
If it comes down to flat plates on the housing, Im golden, but I don't have access to an original car to determine this.

 

There was a Tex Smith article in a late sixties PHR about installing a pre-'57 Olds rear in a '34 with the original trailing arms, I cant remember if he used the coils or a transverse leaf, but it may be helpful either way. I have it fairly close at hand, will try to dig it out on the weekend and post it.

 

George...that would be very helpful...I have lots of old magazines, but very few PHR in the pile.

 

I have a 49-50 olds trailing arm housing laying outside. The brackets are welded on, not clamped so I can't see any reason for any flat spots. Can't say if later ones were that way or not but this one is.

 

Here is a shot of a 9" Ford housing, with 50 Olds arms installed. I don't remember any flat spots on the Olds housing. The brackets on the Olds housing are welded on as Rootie says, and they are a pain to remove and install on another housing, you have to slit the vertical sleeves that the pads index in. I would find a complete 49-50 rearend if you can.

 

Pretty sure the flat portion of the housing was for the snubber to seat on. You can just make it out between the coils of the spring in this pic. The springs would be just inboard on a welded on tab, forward of the axle.

 

This is a 50 olds rear stock hope this helps, theres more on my thread and on the changes the builer and i did to my car aswell

 

Pic #1 is of the flat in the later ('59-'64) axle housing...I was mistaken, the flats are only on the top side which leads me to agree with landseaandair that this is the frame snubber contact point.
Dave50...your photo clears up a lot...thanks for posting it. Ill look for your build thread.
I knew there were rubber bushings involved which is where I got the idea that the trailing arms clamped to the housing.
I can now clearly see what Marty Strode meant when he said the stock bracketry would be a pain to remove and reinstall on another housing.
Now Ill either try and find a stock '50 Olds housing and arms, or possibly cheat a bit and use a set of '60's GM Pick Up trailing arms on the pre-'56 Olds/Pontiac rear end (pic #2) that I just picked up.
Thanks to everyone for their input!

 

I get the feeling you want to do the arms like was done on that car...but, since you will never know; How about skipping those 4 sets of bulky rubber isolators, and use the exact same setup that Chevy trucks arms have? A beefy U bolt, diagonal which means a bit bigger ID U bolt?

I suppose a rodder might have taken the easy way out back then and used all the Olds mounts,...

but then again, on a short rear deck car like an A or a bobbed 32, all that Olds stuff would have looked like **** so close to the back of the car? So, would they have just used a single U bolt to clean it up?

 

More pics of that upside down rear, was a 50 Olds wagon. and 2 pics of chevy arms

 

F&J...I like how you think...
I had to ***ume that the car used the Olds arms as it was an established car when my brother bought it in 1967, but other than myself (and everyone who reads this on the HAMB) who will really know the difference?
A pair of grungy Chevy truck arms showed up in my yard today (its good to have friends) so it looks like the decision has been made for me!

 

I'm using the OEM trailing arm set up from my 46 Olds with a 9" in a friends 42 Chebby PU. Need to step up the frame and add coilovers in lieu of old coil springs. Bushes and rubber pads are still available.

 

Where do you guys get pumpkin parts (gears, bearings and seals) for Olds rears of that vintage? I did wheel bearings on a 54 and could not find anything for the pumpkin which needed work.

 

Back in 58-59 I put a 50 Olds rear in my 31 A using the stock transverse spring. I torched off the upper coil mounting hdwr and left the lower trailing arm mounts. I used the trailing arms by cutting diagonally and welding them back together so I could mount the front portion via the stock rubber bushings in brackets hung down from the frame rails just below the rear of the doors. The rear portion was mounted the way it came from the Olds with two biscuits and bolts each side.
The rear is still under the car, still has the same buggy spring, however I did make some parallel tube bars ala P&J tied to the cross member under a T10 I installed in 76 or so.

 

The article wasn't where I thought it was, but I am still looking. Bear with me...

 

No problem, I appreciate you looking!

 

I have run across the Olds Trailing Arm / Coil suspension in two different projects over the past years.
The first was a 48 Anglia (ex-g***er ???) that I biught in the 80's and the second was a 40 Olds Coupe that I helped build in the late 80's. In either case, I did not find trailing arms welded to the axle housing. Both simply unbolted.
On the 40 Olds we swapped in a GM 10-bolt by using the factory trailing arm / coil springs. Tube shocks were installed and a cross member was installed for upper shock mounts.
Does anybody know exactly what years Olds used this set-up. I would like to find a pair of the trailing arms to use on a 33 Chevy Truck project. I am almost 66 years old and disabled so any information would help. I anybody has a good pair of this type trailing arm for sale please shoot me a PM.......... Thanks, Jeff

 

FINALLY found that article. What threw me off was that it was in June '64 Hot Rod, and Tex Smith did another article in PHR in '68, and used some of the same photos. Dunno if this is still of use to the OP, but here it is.

 

cool read.


"****tersville at the digs"

 

http://www.fabcraftmetalworks.com/ Will help out with internals, bearings, etc. I have had and still have Olds/Pont. rears in my cars. Never seen the flat spot you mention. As far as the trailing arms go I would use the Chevy PU arms.

Pat

 

Actually that article uses the pre '57 rear, same as the op's car originally had, as far as I know, fabcraft makes virtually nothing for it, which is unfortunate, because the early rear was used in hot rods more than the '57 up rear. The '57 up rear was used primarily in race cars.

 

Take the bearings out of the rear, side and pinion. Get the numbers off bearing shells and take to Napa. They can cross match to new bearings. Also my 37 has a 49 Olds. rear with setup shown in Hot Rod, only I did that back in 62. With those Olds. trailing arms the car has always hooked up well coming off the line.

 

I would think the Olds arms will hook a LOT better than the chevy PU arms, as they are a fair bit shorter, will move the instant center back closer to where it should be with the Model A wheelbase, and have some anti-squat.

 

I appreciate you staying with it and posting the article...looks like there's a lot of useful info.
Since the '55 Olds rear axle I bought had previously been stripped of all the trailing arm mounting brackets, Im going with the Chevy truck arms.
I do like your thoughts on instant center, and will look into shortening the Chevy arms to approximately the Olds length.

1934coupe...the flat spots were on a later wide '59-'64 housing. It was mentioned earlier that the flat spots were intended as a spot for the frame rubber snubbers to contact the axle.

Thanks to everyone for their input!

 

I picked up a '39 Olds with the rubber bushed arms clamped around a modern rear end. There was no way to prevent housing rotation. I ***ume because the original was a torque tube which handled this. I was thinking of adding an upper arm from the top of an axle tube to one of the original arms near the front pivot. Or is there a better way?

 

It is only the very early Olds that had those arms. I do not know what year the arms were phased out, but was in the early 50s. Your 55 rear was leaf when new.

Just mentioning this in case someone uses this thread for a future build and parts hunting suggestion.

 

That was one of the initial questions I had when I started this thread, thanks for the clarification!

Phil1934... The early coil spring Olds housings had welded brackets which prevented them from rotating in the arms.
Since you said the arms are clamped on a later housing it sounds like these brackets were wrongly omitted...look closely at the photos in the article FalconGeorge posted, it doesn't look like it would be too difficult to make something similar...not sure which year rears were torque tube.
I wouldn't trust the arms just being clamped to the housing, besides rotation, there is too much chance of the housing moving side to side.