Shock question

jak said:
Just to help give some additional information to help you make a decision. Bratton's is the manufacturer of the US shocks on the market right now. I ran a quick count in my system since April 2022 we have sold over 2,000 shocks all over the world. We have been making this shock since 2016. In the 11 years that we have been making and distributing this shock the last unit that was returned for any sort of warranty work was about 4 years ago. And that actually turned out to be damage resulting from an accident rather than a manufacture defect.
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I thought Bratton's was closed, what did I miss?
 
This is the main roll a shock absorber:

"Shock absorbers are pump-like devices which keep your vehicle’s tyres in contact with the road surface by controlling the reboundof its suspension springs.
As long as your vehicle’s tyres remain in contact with the road, steering, road handling and braking response will be optimal, helping to keep you safe."
https://monroe.com.au/what-are-shocks/shock-absorbers-explained/

A friction shock is unlikely to control the rebound of a spring when it lets go on a good bump.
This is due to the linear resistance, as stated.

However ... there is already a fair bit of friction in a leaf spring, especially if it is rusty.
The main problem with tube shocks is mounting and looks and picking the right ones.
Clean, well lubed springs will need more shock resistance to control the rebound.
 
The other parts sources all offer replacement rotary hydraulic shocks that are who-die copies. None of them give a real good description of these units. Mike's does state that they are sealed and can not be serviced with oil but they are the only ones that state that. All are at the same basic price per unit, ($295.00 give or take) so I have to assume they are all of the same manufacturer, but I have no evidence. Only the sources know for sure. None of them come with the arms, links, or hardware so they are about as expensive as any other similar part such as Rotoshim types.

The tube shock conversions will always be the least expensive way to go in money and time spent. They are obvious if you look under the fenders. Original who-die shocks are generally played out in corrosion and wear. It's getting harder to find any good cores. Any repairs will cost time and energy to fabricate sleeves or weld and re-machine worn out parts. The needle valves, filler plugs, and seal kits are about the only thing folks can purchase for them.

If someone made quality wing shafts and main housings that fit together well, it would solve a lot of problems. These old who-die units were sold for pocket change back in the early Ford era. They never even thought about repairing them.
 
My Fordor came to me with modern tube shocks and 16” V8 wheels with bias ply tires, and the rear spring is wrapped with a leather gaiter. The ride is pretty stiff (but compared with what?). I’ve read on this forum that the appropriate tube shocks must be not be too restrictive, which makes the integrated kits worthwhile (said the poster).
I’m thinking the next step to improve the ride of the Fordor will be to lubricate between the spring leaves. I’d that doesn’t help much, they may need to have rust removed.
 
Reading about early racing cars that had friction shocks (think Bugatti Type 35), they had two potential drawbacks. First, the resistance to compression and rebound were not separately adjustable. Second, their resistance, being based on friction, changes with temperature. As the friction plates heated up the friction (thus resistance) declined. Very tight initial adjustment to cope with eventual heat rise could make them way too stiff in the early stages of the race. I have no idea how much any of this factored into race setup. Supposedly the Bugatti T35’s frame flex was considered an integral part of the suspension system anyway.
 
I have driven Model A’s from my first one in 1967 (‘30 Briggs Town Sedan) until 2020 when I installed restored Houdaille shocks on my ‘31 Deluxe Roadster. I was very surprised at the difference the shocks made - a huge improvement in ride stability and handling.

Since the, I have found 2 more sets of original functioning shocks and have installed one set on my ‘29 Sport Coupe.

I’m a firm believer in using shocks on a Model A, and prefer the original style hydraulic ones.

Jim
 
cars2cool said:
I thought Bratton's was closed, what did I miss?
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IIRC, when Bratton's announced that they were closing, they said they would continue their parts manufacturing.

I was only aware of the reflectors that they were making, not the shock absorbers. Maybe I'll disconnect my links over the winter and see if the shocks actual work. I wasn't bothering, since I didn't know new ones were available.
 
sconnors said:
Would you make this investment in your car? Is there a huge difference in ride quality ($1500 difference) that you will notice when driving versus driving with the friction shocks?
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Yes. And yes.

I have three sets of Rotoshims - and I'm about to get a set for my '34.

Ran some repro A shocks for a while, not sure who made them as they came from a UK supplier - one started leaking the day after I fitted it. The other started locking up. Used to use some uprated MGB lever arm shocks too when I was racing the Tourer. Used various tube shocks and old Houdialles over the years.

And the Rotoshim are night and day different. Mind you, I do press on a bit so your mileage may vary...

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cars2cool said:
I thought Bratton's was closed, what did I miss?
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Bratton's Closed their retail parts business. We are still behind the scenes making parts and suppling them to the other vendors in the market place. Exactly what A&L Parts is doing.
 
Rotoshim has a pretty good web site that gives a good description of how they work. It also frequently states that they are "out of stock". This indicates that sales are on demand since they don't really have a big sales network. A person may have to wait a while to get them.
 
The shims are basically just relatively thin washers that act like a diaphragm. The washers flex like a bellville washer as pressure is applied. This flex allows fluid to flow through the control plate orifices. The shims can be varied in number and thickness to tune the flow. It eliminates having to have an adjustable needle valve and can allow a less viscous hydraulic oil to do the job more efficiently. Rotorshim also applies a pressure to their fluid in order to force it to flow better and provide a balance of pressure in the unit. I have no idea what that pressure is since most of the design is proprietary. It looks like they have a spring loaded ball valve on the back side but I can't tell for sure. It's likely how they fill them but they don't give up their proprietary info for good reason. Otherwise, the Rotoshim works about the same way as a who-die shock with a wing shaft and a housing assembly.
 
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