Question re front spring perches

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RGould1910
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Question re front spring perches

Post by RGould1910 » Wed Jul 01, 2020 4:26 pm

I find the front spring perches are a bit loose when inserted in the axle. perhaps .006" Both the axle and perches are replacements due to the accident I suffered a couple weeks ago. They have been sandblasted. What if anything do people do to create a tight fit? Knurl, shim, forget about it?

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Re: Question re front spring perches

Post by DanTreace » Wed Jul 01, 2020 5:59 pm

Just put new perches in axle for the '25, and they were a slip fit, and think that is ok.

If your used perch shaft isn't worn at the wishbone interface, and have great threads, then should work out.

BTW, in a few years they will be rusted in place :roll:

IMG_4023 (600x563).jpg
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Re: Question re front spring perches

Post by TWrenn » Thu Jul 02, 2020 8:37 am

Wonder if smearing some NeverSeez on the perch shafts would prevent, or at least slow down the "rusting in" process? I
would think it would.


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Re: Question re front spring perches

Post by John kuehn » Thu Jul 02, 2020 9:11 am

Another Ford part that didn’t always fit just as it should when being put together on the Ford assembly lines back in the T era.
I’ve taken out perches that were a bear to get out and others not so much.
It was probably the same when installing them at the factory. The tolerances weren’t exactly right each and every time with Fords parts just as it is with reproduction parts. Close but not exact.
But in my experience I have never been able to just press one out of an axle without using heat. Others will probably differ.
Years of rust makes a difference!


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Re: Question re front spring perches

Post by Wayne Sheldon » Thu Jul 02, 2020 10:08 pm

I have had original parts that were so loose, no apparent cutting, wear, or modification, to explain it. And I have had axles with perches in them that my big old Smith Gauge torch could not get hot enough to free them. Twenty tons of press only mushroomed the perch threads. Once the perch was ruined (not really good anyway, why I wanted to remove it), I cut it off and drilled it out to save the nice axle. No severe rusting (it was so tight there was no rust at all inside) or any other apparent reason why it was so tight.
What can I say? It happens.

Putting one together that is that loose? I know for a fact a lot of people just slip it in, and tighten the wishbone and nut really tight. And hope. Personally, I do not like that idea. It WILL begin to work a bit. WILL begin to rattle. And could eventually cause other issues (the famous Ford loose front end wiggle!).
I KNOW a lot of people consider it BLASPHEMY! The "machinist" mentality. The "we KNOW BETTER today" idea (believe me, Henry KNEW what he was doing!). But I believe that shimming to a snug press fit (takes a little finagling), and THEN tightening the wishbone a few extra foot-pounds is a decent way to go. No excessive heating to built up the surface. No cutting or grinding that may leave a microscopic flaw to develop into a future crack. If it is properly tight! And cannot work loose and rattle. It should be good for a couple hundred thousand modern road miles at least.

That is my opinion.


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Re: Question re front spring perches

Post by RGould1910 » Fri Jul 03, 2020 6:09 pm

Thanks for the input fellas. Wayne, what do you think of the idea of knurling the shafts for a snug fit. If the nuts that hold the wishbone to the perches are tight, do you foresee a problem?


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Re: Question re front spring perches

Post by Wayne Sheldon » Fri Jul 03, 2020 10:03 pm

I have never been a big fan of knurling for fit. Although I will admit to using knurled pistons a few times years ago. The problem is that knurling creates both high and low spots in an attempt to raise the surface and make a tighter fit. In reality, the high spots are not even enough unless one grinds or emery tapes the surface for a final fit, which in fact further reduces the surface from what one started out with. Knurling very often begins to wear a bit, and one can wind up with similar looseness as one stated with.
In theory, ANY indentation or cut on a smooth surface is a potential start of a stress fracture, for any item put under both stress and vibration. And spring perches are very definition of stress and vibration. It is unlikely that knurling would result in a fracture failure. In reality, knurling would probably be fine. But one of the reasons I like the "e-evil shims", is that they at worst become a sacrificial wearing surface. The material for the most part cannot work out, so therefore still help to fill the void even if they do begin to wear. Knurling leaves voids where worn material can hide and return to loose again.
Just my opinion again.

How are you doing since the accident? Still feeling okay?

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Re: Question re front spring perches

Post by TRDxB2 » Fri Jul 03, 2020 11:47 pm

There made an accessory to stabilize a loose perch/wishbone. Steve Jelf was given one for a loose perch last summer at an auction in Indiana.
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Perch - wishbone support.jpg
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Re: Question re front spring perches

Post by RGould1910 » Sat Jul 04, 2020 11:58 am

Thanks for the input Wayne. I am doing the chassis repair myself . Eric says his body and fender man can paint the new fender and splash apron when I receive them from Rootlieb. I'm doing fine after the accident, still struggling with the insurance company. It's a nice car, I'd like to get back on the road. It would be fun to come for a visit sometime after this virus thing subsides.

Frank, that's an interesting accessory. Indicates loose perches have been an issue for some time. Puzzling to me why the manufacturing tolerances were so great.
I've had the same experience as Wayne. Some perches are easy to remove, some can't be removed no matter what you do. Its not always the result of rust.


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Re: Question re front spring perches

Post by Kevin Pharis » Sat Jul 04, 2020 1:14 pm

If the perch to axle clearance was intended to be a precision fit... the perches would have had a ground shank diameter, and the axle would have had a smooth reamed bore. But instead, the axles are drilled and the perches are turned. I don’t suspect that this was ever intended to be more than a “close” fit.

And IIRC, the accessory “support clamps” pictured above were intended to prevent the wishbone from falling off should the perch nut ever come loose or be lost. These clamps could not have corrected any clearance issues between perch and axle. But would be good insurance if you had stripped threads, or didn’t believe in cotter pins or tie wire


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Re: Question re front spring perches

Post by RGould1910 » Sun Jul 05, 2020 6:54 pm

Update. I always enjoy someone telling me how their posted problem turned out, so here goes.
I first tried to shim the loose perches in the axle. No luck. The shims refused to stay put, in one instance they tore. I decided to knurl the shafts with a knurling tool on my lathe. It turned out good and the perches fit with a light press fit . No movement. I didn't care if the knurling made a tight fit because the high spots would compress under pressure.
20200705_154309.jpg

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Re: Question re front spring perches

Post by DanTreace » Sun Jul 05, 2020 9:35 pm

Thanks Richard for the update. Your knurl method seems practical and it worked. Good job. ;)

Once got a used set of spindles from a vendor, and the inner bearing surface was lightly knurled. Probably as the used ones had the inner bearing cone spun on it for a while. The knurl did help the new bearing seat as it should. Plus it is still able to pull that large bearing for grease on occasion.

That large inner tapered roller bearing should only spin between the spindle shaft and the hub inner race, so that the bearing cone doesn't spin on the spindle shaft, nor the large inner race spin in the hub.

knurl bearing surface spindle.jpg
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Re: Question re front spring perches

Post by Wayne Sheldon » Mon Jul 06, 2020 2:51 am

Sounds good Richard G!
W2

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Re: Question re front spring perches

Post by Mark Nunn » Tue Jul 07, 2020 8:41 am

What measurement will you use to set the caster? I find the published caster measurements confusing. In the MTFCA axle book the drawing shows placing a framing square against the axle, not the spindle bushings, and it shows a gap at the top of 1/8". But the text says 3/8". This book and the Ford Service Manual state 5.5 degrees of caster. The service manual shows placing the framing square against the lower spindle bushing and measuring the gap at the upper bushing. It states that the measurement should be between 1/4" and 5/16".

I used this method to check my caster and the upper gap was 9/16". Mine is way out of spec! However, I did the math and found a problem. The spindle bushings are 6" apart. The gap at 5.5 degrees should be .575", or about 9/16". If the gap is 1/4" to 5/16" the caster range is 2.4 to 3 degrees.

Perches are made for an angle of 5.5 degrees and wishbones need to be from the proper range of years to set caster. Wishbones for '26 and '27 have less of an angle where they attach to perches to work in the lowered chassis. Using a '21-'25 wishbone in an improved car would increase the caster 2-3 degrees.

All of this is confusing to me and I am interested to know what your plan is.


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Re: Question re front spring perches

Post by jab35 » Wed Jul 08, 2020 11:45 am

Has anyone out there measured the actual caster angle built into an original Ford NOS front spring perch? Is it 5.5 degrees or something less? I asked this question previously when this same topic was discussed. Mark is correct, the recommended linear measurement values do not give 5.5 degrees caster. drive careful, jb

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Re: Question re front spring perches

Post by RustyFords » Wed Jul 08, 2020 4:13 pm

The worn out, original perches on my 24 Touring were such a bear that I gave up on them and took them to Ross Lilleker.

He was able to remove them, but even he said that they were some of the most stuck ones he'd ever seen. The replacements were somewhere between a press fit and slip fit.
1924 Touring


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Re: Question re front spring perches

Post by RGould1910 » Wed Jul 08, 2020 9:02 pm

Mark you raise some interesting points. I didn't know the wishbones on 21-25 cars were different than the 26-27. I do see the earlier perches are longer above the axle than the 26-27 by about 1/4". That was a surprise to me. I thought they were all the same. The replacement pieces I am using on my car are probably pre 26. The wishbone, the axle and definitely the perches. I may well have more caster than the car had from the factory. But in my case the car was made up from parts so it probably was not correct before the accident.

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Re: Question re front spring perches

Post by Mark Nunn » Thu Jul 09, 2020 8:31 am

I have not compared wishbones in person but this thread has a lot of measurements of wishbones and describes the different angles of the lugs that attach to perches. Early lugs are bent 13 degrees and '26-'27 are 11 degrees.

http://www.mtfca.com/discus/messages/17 ... 1318687549

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Re: Question re front spring perches

Post by TRDxB2 » Fri Jul 10, 2020 1:49 am

I have to wishbones with different attachment lugs and tube construction. see photos. They also appear to be the same size etc. The picture of the gray attachment lug is one that is so worn that the coned nut couldn't tighten against it resulting in a loose perch
perch 2.jpg
perch ends.jpg
perch comp.jpg
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Re: Question re front spring perches

Post by Wayne Sheldon » Fri Jul 10, 2020 2:21 am

Frank B, et al, I believe that odd one may be a very early version of the under-axle wishbone. Mostly late 1918 on TTs and early 1919, the first under-axle wishbones used a flat bottomed nut, and may have been used mostly on the early TT trucks. They developed looseness issues early, and were replaced by the common coned type after only a few months. I have read of these, but never had one myself

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Re: Question re front spring perches

Post by TRDxB2 » Fri Jul 10, 2020 11:26 am

Wayne Thanks for the input. Also the need for a good cone to nut match to tighten down the perch.
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Re: Question re front spring perches

Post by RGould1910 » Fri Jul 10, 2020 8:16 pm

On many wishbones I examined before choosing the one I have for replacement, I saw the imprint of a hex nut from wear on the bottom of each arm where the perch nut rides.

From prior experience I discovered one way to smooth out the contact with the cone shaped nut is to make a copper washer to be placed between the bottom of the perch arms where the hex wear is present and the cone of the nut. The washer compresses into the arm recess and keeps the cone nut from bottoming out on the hex recess before fully tightening the perch. I initially tried a brass washer but it tended to disintegrate . The copper I used was better suited

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