Steering knuckle/trunnion question

[MarkH]

Does anyone know if the large trunnion late model steering knuckles have different diameter threads at the bottom end than the early model small trunnion knuckles?

The upper trunnions didn't change so the threads at the top of the steering knuckle had to stay the same, but not having one in hand, I don't know about the bottom.

[R-Sargent]

I cannot answer that question yet but over the next few months i have a 53 and a 54 aero to do trunion replacement on . If the early style do not work on the 54 then i will be looking for parts again.  I was under the impression that all they changed was the angle on the trunion to get more camber in 54 but no where can i find if the bolt size stayed the same or not.

[MarkH]

I cannot answer that question yet but over the next few months i have a 53 and a 54 aero to do trunion replacement on . If the early style do not work on the 54 then i will be looking for parts again.  I was under the impression that all they changed was the angle on the trunion to get more camber in 54 but no where can i find if the bolt size stayed the same or not.

 According to a Willys service bulletin, the early '52 trunnions were 2 1/2 degrees off of a straight 90 degree cross to provide friction to the steering support threads. Later in '52 they went to the 90 degree trunnions and stayed that way. Rareparts.com has a supply of the early trunnions kits, and the upper trunnion kits.

There's definitely a large bolt trunnion, from what I've heard for the late model cars with the 226 engine. The early control arms & trunnions use 5/8" bolts, the larger trunnions use 3/4" bolts, with lower control arms threaded for the same. I have a small trunnion car and an NOS set of large trunnion control arms, the only difference being trunnion bolt size. I'm in the process of having some new trunnions machined and am wondering if they'll not only work to retrofit large trunnions to an early car, but also be a direct fit for the late model steering knuckles. I just don't have any knowledge about the steering knuckles on the later cars.

[Aeroman]

Mark H has it correct.
803009 is the part number for the 1952-1953 steering knuckle support (between the two trunnions).
910959 is the part number for the 1954-1955 steering knuckle support.
The parts books don't give me further info.

[MarkH]

Visited my brother this past weekend and picked up the new trunnions he helped make. He'd been waiting for a left hand threading tool to come in so they could be done. I just finished tapping in the zerks & cutting the bolts to length, thought I'd post a pic.
He machined them extra thick so I could tap the zerk in the bottom and skip drilling & tapping the bolts.

[Barnum]

Looks like really nice work !

[Aeroman]

Things of beauty! What type of metal are they made from? Does your bro want to produce a run of bolts?

[MarkH]

Things of beauty! What type of metal are they made from? Does your bro want to produce a run of bolts?

They're regular steel, I can't remember the Rockwell number but my brother's machinist buddy said it's comparable to a factory trunnion I sent along. I've got to get them coated pretty soon, some rust is starting to show.

He never got interested in the bolts and I was so happy about the trunnions that I said I could "make" the bolts. They're 3/4 coarse thread x 1 1/2 in grade 8 with a couple threads cut off. Factory bolts are 1 1/4 inch length and are a couple threads short of filling all the trunnion cross threads, which aren't that many to begin with. Small trunnion cars would take 5/8ths coarse thread.
I tried to order some 1 3/8ths bolts but only 1/4 inch increments are available which is why I cut some down, and maybe why the factory opted for slightly short bolts.

Since I don't need drilled bolts I didn't explore what it would take to drill down 1 3/8 through grade 8 or grade 5 bolts, or even what the hardness is on the factory bolts.

[kaiserfrazerlibrary]

Take a look at this .pdf file.  It's a service document issued in 1955 and covers additional information on the Aero front ends, all model years as noted.

It's already been added as part of the update package for the next release of KFOCI HANDBOOK

[MarkH]

Take a look at this .pdf file.  It's a service document issued in 1955 and covers additional information on the Aero front ends, all model years as noted.

It's already been added as part of the update package for the next release of KFOCI HANDBOOK

This is interesting, I have an incomplete set of service bulletin copies but haven't seen this one. It appears to confirm that the trunnions I have would only work for what I'm doing, mounting '54/'55 large trunnion control arms to an early steering knuckle.

If I'm reading this right, it also looks like the late model cars used one 4" through bolt with a nut in the trunnion rather than 2 short bolts.

Any of you late model guys want to weigh in on this?

[vettelang]

I just took off my lower control arm and the bolt is a single long one. FYI