Brass Bushing Clearance - 1965 Volvo 122s Steering Box

[hensh_ma]

I'm having a machine shop take a look @ my steering box with the rebuild kit I purchased from VP Autoparts. He took some measurements before doing any replacement.

He said my cap bushing is ovaled out - difference from shaft to bushing anywhere from 3.5-4.5 thousands of an inch. There are two bushings inside the steering box body - one is at 2.5 thou clearance, other is 3 thou.

Idler arm bushing was completely shot, he replaced without measuring, estimated to be 6-8 thou. He redid them and set the clearance to 1 thou.

My question - does anyone know what these clearances were from the factory? The service manual doesn't have these numbers, it just mentions to use SVO Tool 2225. Trying to figure out how far these are out of spec.

 

[dl242gt]

Are the bushings pressed into place? Usually there is deformation from being pressed in and then the bushing is honed to fit. Similar to kingpin bushings are honed after pressing in.

 

[hensh_ma]

@dl242gt Yes, they're pressed into place and reamed/honed to fit. That's what the machinist did when I say he "set" the clearance to 1 thou for the idle arm bushings

What I'm trying to understand is if there is a factory spec for what "fit" means in terms of an actual measurement

 

[mikep]

When i worked at ford and gm dealers we set them as close to zero as possible, like half a thousandth. This is not a spinning shaft, it just needs to move freely.
On mg/triumph before that we never measured, just honed a wee bit at a time until it went in.

Don’t forget to throw it in the parts washer and then dishwasher. Any grit will stay there until it wears stuff out.

 

[dl242gt]

@dl242gt Yes, they're pressed into place and reamed/honed to fit. That's what the machinist did when I say he "set" the clearance to 1 thou for the idle arm bushings

What I'm trying to understand is if there is a factory spec for what "fit" means in terms of an actual measurement

That's a measurement you'd have to get from ZF archives would be my guess.

 

[hensh_ma]

That's a measurement you'd have to get from ZF archives would be my guess.

following up here, just for the sake of it. Was able to get things sorted but didn’t end up finding much in the ZF archives.

Machine shop was also able to replace brass bushing in the Steering box cap, which was originally cast in (see photo where the holes In the bearing were used to mesh with the aluminum during casting), which I thought was interesting although I’m sure already known in this forum. To get the fit right, he just took off a skiff more than it took to get an “interference fit” with the top cap installed.

Additional findings: idler arm “bolt” was severely pitted and corroded, but only in one spot (the “empty” space between the bushings filled with water, probably) and the new bushings were all 100% brass, while the originals from ZF were steel-backed brass. Something about “strength and rigidity”

It’s all play-free and smooth and silk now.

 

[dl242gt]

Well done. Glad you have a good machine shop to help you fix this kind of issue. Sort of like the issue with the top cover on the trans. When that bushing needs replacement. You need the good machine shop as one method to repair that.

 

[blkaplan]

If you can get an actual round hole, .0005" Clearance should provide a nice sliding fit.

 

[hensh_ma]

@dl242gt fair point. Although based on my recent M40 findings, that may be solved through a T5 swap. Time will tell.

@blkaplan could be, but I just agreed with what the machinist said, which was 0.001". His security system consisted of a pump action shotgun with the words "WATCH DOG" painted on the side, and the trigger was connected with a string from the trigger to the door. So I didn't push it.

 

[283SD]

They have to be line bored just like kingpins otherwise you will not get the proper fit. [001to002"]. Trust me, been doing this for years. Have over a dozen pilot reamers just for that reason, 9/16" to 1&1/4, cost 1K+ for all of them.

 

[hensh_ma]

@283SD Yes, that is what was done. The brass bushings sent in the replacement kit are oversized, so when they're pressed in, you can't get the shaft and throughbolt to fit without reaming. He followed what he said were general specs for kingpins - 001 per inch of material

 

[dl242gt]

Funny you mentioned king pins. Years ago I bought the reamer you need for doing the air cooled Beetle version. A cool reamer they make is adjustable. I bought one of those to do rocker arm bushings.