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Flash's 1965 Ford Thames


Flash

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4 hours ago, Valiant said:

Gday mate. 

Re multiple belt pulleys I turned up a basic hub for my a15, then bolted a couple of old water pump pulleys I got from a wreckers yard to it.     Worked out well.

That's a bloody good idea Pete. I've got a spare water pump pulley here. I might just dig it out and see how easy it would be to do the same. Thanks for sharing.

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  • 1 month later...

Also maybe have a look at what angle the arm was in relation to the pushrod in the old setup, pedal at rest angle and brakes applied angle. My mind says they should be at right angles to each other at full brake application 

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25 minutes ago, cletus said:

In nz, for cert that design would have to be approved due to its complexity, I dont know what the rules are like over the ditch but that would be very difficult to get legal here 

Thanks for that Clint. I've just emailed my concept drawing through to the Certifier that I am using across here and will let you know what he comes back with.

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13 minutes ago, Mof said:

Have you got enough stroke on that little lever arm?

 

9 minutes ago, Mof said:

Also maybe have a look at what angle the arm was in relation to the pushrod in the old setup, pedal at rest angle and brakes applied angle. My mind says they should be at right angles to each other at full brake application 

Thanks for sharing your thoughts Mof. I'll check both out in the morning.

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1 minute ago, Nominal said:

Seems to be a lot of interest in this one in NZ

https://www.trademe.co.nz/2808126999

Yep, I've swapped a few yarns with him in the past. He was planning to do an engine upgrade a few months back and made the mistake of posting his intentions on the 400E FB page. He got so badly flamed by the Barrys on there I felt bad for him and sent him a sympathy email. Needless to say I'm keeping a very low profile on FB about what I am doing :-)

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1 hour ago, cletus said:

In nz, for cert that design would have to be approved due to its complexity, I dont know what the rules are like over the ditch but that would be very difficult to get legal here 

I couldn't agree with you more mate; hard not to dispute that the NZ LVVTA  'old boys whiskey club' would be both loud and vocal in their objections.

In my opinion  if the ratio's & engineering (i.e. design, materials and construction) were of an acceptable standard the linkage would be no more complex than many production cars (the RHD E30 or Mk 1 Escort springs to mind). 

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So you removed the spring from the Thames shifter and the lever is too heavy for the gearbox to pull it to the 3-4 position, is that what you're saying? I got a bit lost.

Does the Thames lever drop without the spring? 

Can you just shorten the length of the thames spring until the lever rests in the 3-4 position?

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Hey @Mof, thanks for checking in. I really appreciate the interest that you have shown with regards to my latest challenge. You are right it does all sound a bit confusing. I'll try to do the subject a bit more justice here. (Apologies in advance for the information overload)

So first off is the Thames column shifter and gearbox. In its original format the column shifter has two internal springs within the lever mechanism. The first spring is positioned vertically and essentially pushes the shift column to the bottom position (or gear gate) at rest. The second spring is positioned horizontally and is used when engaging reverse. To engage reverse gear you pull the handle out (towards the passenger side). This causes a pin inside the column to disengage and the first spring I mentioned then causes the column to drop even further which then allows you to engage reverse gear. 

Now we get to the 5 speed HiAce gearbox. It has two side mounted levers. The first lever I call the gate lever. Lying under the van and operating both levers by hand you get the following results:

The first lever which I call the gate lever has three positions. Pulling the gate lever towards the back of the van gets you to the gate for 1st and 2nd gear. If you let the gate lever go an internal spring within the gearbox selector mechanism returns the gate to the "at rest position" which is the gate for 3rd and 4th gears. If you then push the gate lever towards the front of the van it moves to the gate position for 5th and reverse gear. Then when you let the lever go gravity causes the lever to return to the "at rest position" being the gate position for 3rd and 4th gears. A standard HiAce van uses solid rods to link the column shift to the gearbox levers with no return springs in either the column or the rods, so the gravity return works perfectly.

So now we get to mating the Thames column to the HiAce gearbox using push pull cables rather than solid connecting rods.

The first issue is that the up down movement in the Thames column which previously allowed for two gate positions now has to suffice for three gate positions for the HiAce box.  This makes the 3 gate positions very close together and its almost impossible to "find" the middle gate position without having some sort of reference. To make matters worse "at rest" the setup sits in the 5th and reverse gear gate position (due to the vertical spring in the column). Invariably when you lift the handle to engage 3rd or 4th gear you end up engaging 1st and 2nd by mistake due to the small amount of movement.

So my first thought was to try to lengthen the stroke to give more separation between the gates. I managed that fairly easily by removing the horizontal spring which left me with a floppy handle. I then jammed the handle in the outwards position which then essentially doubled the up down travel of the column by giving me the full vertical range movement from 1st all the way to reverse (hope this makes sense). Okay so now I have separated the gates more and its a bit easier (but not much) to tell the difference between the position for each of the three gates, but the vertical spring still causes the column to drop to the 5th and reverse gate at rest. So then I removed the vertical spring in the column which left me with a "floppy" gate selector within the column. Now my theory at this point was that the shift return mechanism within the HiAce gearbox would take over and this is where things went awry.

The HiAce spring that returns the gearbox lever to the "at rest" position is just not strong enough to feed all the way back to the column handle. I suspect that this is due to some residual force within the cable (which is 3.7 meters long) as well as the ball joints that I am using on either end of the cable. To make matters worse the gravity return used when in 5th and reverse doesn't work at all. Both issues result in chronic cases of mis-shifting where either you aren't positioned at a gate correctly so you can't engage gear, or you end up at the wrong gate and then select the wrong gear.

As mentioned in my post I've tried a number of combinations of springs. I've played with the strength of the internal HiAce spring which resulted in sometimes "overdriving" the mechanism so that it then skips over the "at rest" gate. I've also tried external springs on the gate lever to assist the gravity based return. I've also tried various springs on the levers at the bottom of the column shift and whilst I have been able to improve things, the results are still inconsistent.

I could carry on fiddling about, but at the end of the day am I going to get a consistent result that will last for the foreseeable future, or am I going to constantly have to muck about with this to keep the mechanism sweet as the cables age and spring tension varies.

The goal has always been to make this van our daily driver and as much as I'd like to retain the factory look of the column shift at the end of the day drive ability is key. Whilst I personally may be able to muddle along with the inconsistent gear changes it would dilute the enjoyment of driving the old girl around. It would also be unfair on my missus who will be driving the van. I'm also concerned about how the Certifier will react if he had to deal with mis-shifts while driving the van during the cert process.

So that's kinda where I am at Mof. Again apologies for the information overload. 

As always I'm open to any fresh ideas.

Thanks again.

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