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Above axle wishbone

Posted: Mon Jun 10, 2019 2:53 pm
by Rayoung
Can anyone tell me what parts need to be replaced to convert to a bottom mounted wishbone? Or am I better off just adding a wishbone support from one of the vendors?

Thanks
Ray

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 3:05 pm
by Steve Jelf
Mechanically you'll need a different wishbone ((2733B) and nuts (3821B). Aesthetically you want different perches (3818B & 3819B). That's for just switching to the later wishbone.The accessory support is a good idea, but I'm not sure what extra parts it requires. I expect the parts dealers can answer that.

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 3:13 pm
by Rayoung
Is there any difference in the axles between top and bottom mount wishbone? The car is a 23 but has the older style wishbone. I’m starting to wonder how many cars went into the making of mine.
Also, thank you for the quick reply Steve.

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 3:49 pm
by Oldav8tor
I don't think there is any difference in the axle. My 17 had the upper wishbone so I bought a bracket on ebay and fabricated an accessory wishbone from steel rod with later model eyelets welded on. Looking at other cars, folks have fabricated many different solutions to this problem that seem to do the job.

clamp: https://www.ebay.com/itm/Model-T-Ford-f ... XQDjhQ5wIi
Ends: https://www.ebay.com/itm/Model-T-Ford-l ... ctupt=true

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 4:18 pm
by Wayne Sheldon
With a pre 1919, I would recommend an added brace to keep the car correct (not enough '17 to '18 Ts still have the right style as they have been changed out over the years.
However, anything after 1919 should have had the under axle wishbone, so I would recommend replacing with correct later parts. (How can you argue against stronger and safer when it is also more correct.
The only parts that need to be replaced are the perches, nuts, and wishbone itself. However, changing perches in the axle can be a tough, annoying, and often damaging project. I would recommend getting a later axle with good perches or an axle with no perches and install the later perches. Unless yours is really nice or already rebuilt, now would be a good time to rebuild it. If yours are really nice, you can use your spindles and peripheral pieces on your replacement axle.
The bonus is, that the earlier over axle wishbone and perches are considerably more valuable than comparable later pieces. And you may want to check if the axle itself might happen to be a Dodge Brothers stamping. The Horseless Carriage crowd goes crazy over those.

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 4:29 pm
by Erik Barrett
The early perches are not long enough to properly attach a later wishbone. When we build double wishbone speedsters and race cars I mill the axle 1/8” on top and bottom so the perch protrudes through the lower wishbone far enough to use the correct conical nut and cotter pin.

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 5:45 pm
by Russ T Fender
I was able to add the lower wishbone to all my early cars using a '26/'27 wishbone and the thinner drive shaft pinion nut. No modification required other than removal of the wishbone ball.

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 7:23 pm
by Mark Gregush
I don't think using the flat driveshaft nut when using the later wishbones is a good idea. The hole in the wishbone is conical for a reason, to keep them centered when installed. Just because you add them as under braces (?) does not mean they are not going to work back and forth reducing their usefulness a brace. While maybe not ideal as you will loose some thread on top, I would cut back that later nut and cut new slots. You would center the wishbone and actually there would be a little more thread then using the driveshaft nut.

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 8:03 pm
by Scott_Conger
Mark

you're right
FWIW, early 1919 radius rods were flat and had flat bottomed nuts (there was no spherical surface). Not many people know this and it is highly unlikely that Val used one of those...just thought you and others might like to know.

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 8:09 pm
by Mark Gregush
"I would cut back that later nut", should read; I would cut back the later wishbone nut.

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 8:24 pm
by Retro54
My dad did the double wishbone with his '16... but if you are lucky as I am with my '15, you might also run across something like this. An uncommon accessory spring, perches and wishbone mount... many ways to skin the proverbial cat.

Re: Above axle wishbone

Posted: Mon Jun 10, 2019 9:22 pm
by Rayoung
Thanks for all the replies. Gives me lots to think about. I’ll likely start searching for the proper wishbone. Does anyone know of anybody in southern Ontario that might have a decent wishbone for sale?

Ray

Re: Above axle wishbone

Posted: Tue Jun 11, 2019 12:17 am
by Steve Jelf
If the car is a 23 I agree with Wayne. Forget the brace and just go with the later wishbone and perches. As for changing the axle, it may be easier to find an axle with the later perches already in it rather than changing just the perches. Sometimes removing perches is easy, but often it's the job from Hell. The parts book shows the same axle for all years, so I think the only thing that changed on axles were the markings.

Re: Above axle wishbone

Posted: Tue Jun 11, 2019 1:15 am
by kmatt
If you have the straight steering arms that go with the 1918 and earlier over axle wishbone you will need to change them to the later type offset arms
to clear your new under axle wishbone.

Re: Above axle wishbone

Posted: Tue Jun 11, 2019 9:15 am
by Russ T Fender
I guess I should have mentioned that I took a light radius cut on the nut when I used the later wishbones. I did not contour the nut to be flush with the concave contour of the wishbone however, just enough to seat it in the contour a bit. I have not had any movement on any of the ones that I did and I run down some pretty rough dirt roads on a regular basis.

Re: Above axle wishbone

Posted: Tue Jun 11, 2019 4:30 pm
by Wayne Sheldon
A lot of good advice here.
And Kevin M, Good catch and call about the spindle arms!

Re: Above axle wishbone

Posted: Tue Jun 11, 2019 7:44 pm
by Rayoung
It’s surprising how changing one part can lead to so many parts. Glad I asked and thanks for all the advice.

Re: Above axle wishbone

Posted: Tue Jun 11, 2019 10:33 pm
by JEC
Can someone point me to a link that describes the problem with the early axle/wishbone?
I have a 15 runabout that probably should be looked at in reference to this.

Re: Above axle wishbone

Posted: Wed Jun 12, 2019 7:28 am
by George Mills
John C.

Don't know of a clean link...but here's the meat....

Triangles and pins were the science of the day when it came to designing. In an engineering sense, you know where the load goes exactly without worry of what is called load sharing and where it might go or how it is split. The Model T is loaded with triangular systems, some visible, some you have to look for.

When the T was designed the decision was made to have the front axle resist reactionary road loads by running a triangular frame (wishbone) from the top of the axle to the ‘pin’ (wishbone ball). This kept the axle square in a 'bump' and provided resistive force to keep the front pocket frame forging from seeing a very amplified load due to its distance above the road surface.

This got by for a while and somewhere along with the introduction of ‘concrete’ and paved roads there are stories of instances where the front end ‘knuckled under’ in catastrophic manner. (Read…banging into chuck holes, potholes, gopher holes, etc.). I’m not sure of how many or how often these did occur but the lore goes that Henry was out on one of his team adventures and the car they were driving wound up ‘knuckling under’ the front end. (No mention of why, it just did. It could have been the ball cap falling off…could have been loose perches…could have been a host of things in combination). What is reported is that Henry apparently said something on the order of “Fix the darn thing so that doesn’t happen again!” and they did…by moving the wishbone mounting point to below the axle.

What did that do? In an engineering sense for the same disruption at the road, it halved the load that the perches, and spring mounting forging ‘saw’. Places like Western Auto and others then came out with retrofit kits for a double wish-bone, the original remained in place over the top, the new kit mounted from below. Not as straightforward in the statics and dynamics side of engineering…but because of another 'design' triangle formed in both planes much greater stiffness was actually attained and it didn't matter which set handled the real load (kind of like belt and suspenders).

Re: Above axle wishbone

Posted: Wed Jun 12, 2019 9:30 pm
by Oldav8tor
I quote Kmatt "if you have the straight steering arms that go with the 1918 and earlier over axle wishbone you will need to change them to the later type offset arms to clear your new under axle wishbone."

I have a 1917 with an over-axle wishbone. I've fabricated an auxiliary under-axle wishbone which I have yet to install (engine isn't back in yet either.) Do I need to install different steering arms? That's the first I've heard of anything like that.

Re: Above axle wishbone

Posted: Wed Jun 12, 2019 11:59 pm
by kmatt
NO you don't, the era accessory under axle wishbone brace meets up with the stock over axle wishbone in a way that it is not necessary to change the steering arms, in fact they were designed and used long before Ford's later design. I have a era accessory under axle wishbone brace on my 1916 express. When Ford designed the later under axle wishbone of 1919, because of the way it curves up to pan with very little bend to keep it as straight as possible they had to change the steering arms to the later type.

Re: Above axle wishbone

Posted: Thu Jun 13, 2019 5:37 am
by Wayne Sheldon
Yes, the after-market wishbone braces preceded the improved wishbone by several years. I have seen advertisements and photographs dated as early as 1912 showing the wishbone braces.
One of the weaknesses of the over axle wishbone on modern roads and modern speeds, is oscillation, which can be caused by many factors of the road surfaces, bumps, potholes, etc, then a speed/time/cycle factor kicks in. Once oscillation begins, it can be difficult to break the cycles, and disaster can be imminent. The added brace helps prevent oscillation from getting started.

Re: Above axle wishbone

Posted: Thu Jun 13, 2019 4:59 pm
by Oldav8tor
Thanks - I looked at my steering arms today and they are not the straight version as on earlier cars (see attached photo.) I think I'll be OK.

I got the idea to install an auxiliary wishbone after reading an account from the period of Henry Ford being thrown from a Model T not far from where I live when his speeding T his some soft sand and the axle knuckled under. Apparently it still took a couple of years for the wishbone to be changed as Henry had to use up the stock he had on hand. Obviously it was a known deficiency because people were adding under wishbones for years before the design changed.
arm.jpg

Re: Above axle wishbone

Posted: Thu Jun 13, 2019 10:43 pm
by Angmar
I switched mine over just to be safe. My front axle was very worn out so it seemed like a good idea to do it while I had it out.