Gearbox springs

[worzel]

Hi

Any ideas on this one? For those who've tried in the past, finding an means of "biasing" the gearlever to the 3rd/4th plane on a modified Type 9 box isn't too easy. I know the AV conversion works but looks like it involves a lot of internal mods to the innards. I know of a few other ways of achieving this but they all fit in such a way that if problems develop the engine/box assemble has to come out

I (think) I've come up with a really simple idea that involves the use of a spring loaded plunger (not my own invention I'll admit since I've lifted the idea from the Toyota box fitted to late Excels). The advantage is that removal is easy and leaves the transmission in place

My problem is I don't have access to a suitable Excel box so I can check what the spring rate might be. If I use too soft a rate in the custom plunger I've had made it's going to be too easy to slot from 2nd to 5th inadvertently. Too stiff a rate and it might be a struggle to engage 5th.

I know some might say just fit it and see how it feels since it is easily removed -but- the initial fitting still requires the box out and I want to be 100% sure it works the way I envisage with the right feel.

If they're thinking of doing a T9 conversion. What I really need is some info on the likely spring rates required.

Regards

John

PS It's not just for my own benefit since I'm quite happy to let others use the idea if they want

[CBUEB1771]

I know the AV conversion works but looks like it involves a lot of internal mods to the innards.

John,
I'll apologize in advance for not answering your question. I am currently installing an Alan Voights T-9 conversion in my +2. If you are referring to the spring loaded plunger he adds to the top cover, this has nothing to do with biasing toward the 3-4 plane. The function of this device is to provide a strong bias away from the reverse plane. If you remove this device altogether the converted T-9 still has a light, but very perceptible bias to the 3/4 plane. I am pretty sure this comes from a spring in the gear lever assembly itself, much as in the Cortina-derived four ratio gearbox. At this point I am planning to discard the Voights anti-reverse biasing system because it is very heavy and notchy. The reverse and 1/2 planes are far enough apart that I think it would be tough to select reverse in error. I'll be completely dismantling my converted T-9 after completing my trial fitting to the +2 and will report on anything else that might contribute to a bias toward the 3/4 plane.
Russ

[worzel]

Hi Russ

Very interesting.

I'm pretty sure the gizmo in the lid works on a ramp/cam- probably(possibly) a spring plunger that sits against the large interlock washer- when you try to select reverse it probably moves the washer to the point where the ramp meets the plunger head and provides resistance against reverse. The washer has probably been ground down about a tenth of an inch along its upper surface for about one inch. The only reason I say this is that long before AV got their kit to market I had them machine an item on my own converted box.

Mine uses a cam arrangement but it's not so noticeable and sits much lower in the lid. I didn't design the reverse lockout system on my own gearbox so I'm not claiming the credit but I'm pretty sure AV "adopted" the idea for their own use since at that time they were trying to figure out how to provide a lockout for reverse.

I'm interested in how your gearbox biases the lever rightwards- you say there is a spring mechanism- is this actually on the lever itself ie outside of the internals or have they modified the original Ford item that was originally located forward of the gearlever and instead somehow located it behind the lever- in the round tubular section just behind the lever?

As I said in the earlier post I know of a couple of ways to achieve this bias but some are bulky because they have to be fitted to the lid- I'm hoping mine is both easily adjustable for the level of resistance (by altering the springs) and can be replaced easily if the springs lose their strength without taking the box out.

Regards

John

[CBUEB1771]

I'm pretty sure the gizmo in the lid works on a ramp/cam- probably(possibly) a spring plunger that sits against the large interlock washer- when you try to select reverse it probably moves the washer to the point where the ramp meets the plunger head and provides resistance against reverse. The washer has probably been ground down about a tenth of an inch along its upper surface for about one inch.

John,
You are correct in your description of how the AV anti-reverse bias device works. There are problems with the design and manufacture. The plunger is a piece of round stock that has a ramp ground onto its end to engage a recess and corresponding ramp cut into the interlock disc. Unfortunately there is nothing to control rotation of the plunger and the ramp can move out proper orientation with the mating ramp in the disc. This of course results into a "driving into a wall" situation rather than a nice cam action. If the bottom of the plunger was ground to a hemisphere and not an angled plane this problem would not occur. Another problem in my gearbox is that the recess cut into the disc is too short (circumferentially) such that the plunger has to start to lift long before you get to the reverse plane and actually prevented me from getting into the 1/2 plane. Seems there wasn't much testing done before my converted 'box shipped. As I said yesterday by removing the plunger assembly I can select all gears very nicely. I'll report more on how the 3/4 plane bias is accomplished when I take the 'box apart.
Russ

[worzel]

Hi Russ

Thanks for the info- I'd definitely be interested in seeing how the lever "springs" back to the 3rd/4th plane.

I'll try to describe the system on my own car- I did take photos last year but unfortunately the only copies were on the hard drive and I had to replace it when a fault developed. The plunger on mine is actually the same as the one from the forward end of the box that is retained with a hexagon driven grub screw- it also uses the same springs.

Looking at the lid of the box from the rear approx 1.25 inches inwards from the edge of the lid and in the same plane as the interlock "D" washer is welded an internally threaded tube of about 1.75 inches. This is at an angle of roughly 45 degrees to the horizontal/vertical. This tube effectively fits between the parallel walls of the "guide" that holds the "D" washer in place- the walls are drilled only part of their length so that the actual plunger cannot fall into the box.

Using trial and error a shallow recess of about 3/4 inch is ground in the edge of the "D" washer to provide resistance to reverse- on my car this recess also acts as a resistance against 5th. The plunger can rotate but it doesn't matter since the end is left as a dome anyway so it always sits correctly against the "D" washer. By altering the angle of the ramp the resistance against reverse is made greater than against 5th (or can be achieved by fitting weaker springs). The system works very well with 5th easy to engage and reverse a fair bit harder for obvious reasons.

Regards John

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