NUBODI Automotive - Manual gear knob on an auto

Nubodi Automotive · #1 25th March 2016, 19:04

Fitting an aftermarket gear knob on an automatic car with 'lock out'

Nubodi Automotive · #2 25th March 2016, 19:04

I apologise if the following instructions are a little long winded for the more experienced builders on the forum but it’s aimed at everyone, some with little fabrication knowledge.
I wanted to be able to use an aftermarket (nice) gear knob on my automatic car. The problem with some automatic gear knobs is they incorporate a ‘lock out’ mechanism to lock the lever in the ‘park position. Some older designs have a disc you can lift to move which allows the gears to be selected. However most do not have this design. The usual auto gear knob is generally plain or boring. The example here is a BMW Z3 automatic gear lever on our demonstrator 250 SWB Kalifornia. To select reverse you have to press a button in at the front of the knob which lifts a plastic rod which allows the lever to come out of park. This is an age old problem and one which there does not seem to be a simple solution to. So I have devised a solution I think works well and is simple to replicate.

Nubodi Automotive · #3 25th March 2016, 19:06

First I had to remove the gear lever. Select ‘drive’ without the engine running. Pull up hard on the knob with a slight twist at the same time. It should come off. It’s only a force fit so it may take a couple of goes. Don’t hit yourself in the face when it does release! You are then presented with a forked end. I found an M12 large repair washer and carefully filed it till it went over the end of the shaft with a sliding fit. An identical washer was also made.

Nubodi Automotive · #4 25th March 2016, 19:07

A spring was then fabricated from some garden wire. Obviously you can buy a spring ready made and cut it down if it needs it.

Nubodi Automotive · #5 25th March 2016, 19:07

Because we removed the plastic lockout shaft we have to fabricate a replacement. I found a very long M10 bolt that fitted into the hollow shaft of the lever. The threaded end was ground down to copy the end of the plastic one. The head was then cut off with an angle grinder. Just make sure the bolt does not protrude from the end of the hollow shaft or it may foul the new knob fitting.

Nubodi Automotive · #6 25th March 2016, 19:09

With the bottom washer on the shaft drill a 5mm hole just above the washer through the centre of the shaft as shown in the picture. Once you have drilled through to the other side slide the bolt back into the hollow shaft. Mark the bolt with a marker or the drill. Remove the bolt and drill a 4.5mm hole through the centre. Tip: grind a small flat on where you want to drill the hole on the bolt to stop the drill bit slipping on the round surface.

Nubodi Automotive · #7 25th March 2016, 19:09

Then with the 5mm drill bit elongate the hole you drilled earlier by carefully applying pressure upwards. The slot needs to be around 12-14mm long. You can tidy it up afterwards with a small rat tailed file.

Nubodi Automotive · #8 25th March 2016, 19:11

Find a suitable M4 bolt (about the same length as the diameter of the bottom washer) and cut the head off. Put an M4 nylok nut on one side and thread it through the hole in the shaft and through the bolt too. Place another M4 nylok nut on the other side. Fasten them equally but not too tight. You need the same amount of thread sticking out each side and loose enough so the bolt moves easily in the hollow shaft.

Nubodi Automotive · #9 25th March 2016, 19:14

Grab the washer and lift up, it should slide easily upwards releasing the lock out mechanism. If all is well, then add the spring and then the top washer.
The aftermarket gear knob can now be added to the top of the shaft.

Nubodi Automotive · #10 25th March 2016, 19:17

Without the engine running check the lock out stops you selecting any gears when the ignition is turned on and the foot brake applied. If so lift the bottom washer with a finger either side of the washer, upwards and then pull back on the gear lever, you should be able to select reverse.
I found that I could actually use this method without the spring and top washer as the weight of the bolt was enough for gravity to return the bolt without a spring. However for safety’s sake it is a good idea to leave it in. This works through a gaiter also which is also a bonus.

For vehicles that are a lookalike or replica and never came with auto boxes a knob with a manual shift pattern can be added to create the illusion of a manual box.

Paul L · #11 26th March 2016, 07:21

Richard - Great post.

I also liked the way you used the ash tray to hide some switches.

Next time I get a chance to update the Useful links thread I'll add this to it.
( You are turning out SWB 250s so fast I can't keep up!

)

Cheers, Paul.

Nubodi Automotive · #12 26th March 2016, 07:44

Hi Paul
We don't just churn out 250's. There was a rumour going around that I slept occassionally...obviously that's nonsense!
Heres a Kobra we finished recently for a customer. He is making it into an AC Ace style one with chrome wires and period accessories. When its finished I'll upload more photos.

DaveP · #13 26th March 2016, 08:35

Oooooh I like ! and great to see Cobras getting a look in still...

The red is a great colour on the Kobra/Cobra. I also like them without the centre stripe once I a while too.

And the use of the square lucas rear lights is still to be appreciated. Shame we, as road users, have to keep to the law and have additional indicators though. But we do what we are told.

But back to the other part of the thread. Thanks for the pictures of the gear stick mod Richard. Ingenious !

Dave

WorldClassAccident · #14 26th March 2016, 09:53

I like the conversion you have done but my interior is already trimmed so the gaitor won't cover the washers etc so I am trying to think of alternatives. First can I share what understand about the mechanism to see if that is right.

1) At the bottom of the hollow gear stick there are some notches that the plastic shaft (or bolt in your conversion) get stuck against preventing you moving the gear stick out of Park.

2) The button on the auto knob or the washers on your conversion move the shaft/bolt up so it is no longer stuck against the notches and the gear stick can move.

3) When you let go of the button/washers the shaft/bolt drops back down and locks the lever in place again. There are no notches between Drive and the lower gears so even with the shaft/bolt in the lowered position you can slide between these gears but there is a notch to stop you sliding forward into neutral or reverse by mistake.

If these assumptions are true - please correct me if they are not - there are a couple of possibilities that spring to mind.

A) Remove the shaft and just hope I never hit Reverse when travelling forward. High risk but easy.

B) Fix a shaft / bolt to to bottom of a nice heavy manual gear know and then simply lift it over the notches allowing the weight to drop it afterwards. Just need a heavy knob and some way of fixing the shaft to the bottom of it.

I will see what appears at the autojumble on Monday

Nubodi Automotive · #15 26th March 2016, 12:28

1. correct
2. correct
3. correct
a/ not advisable
b/ Yes but the shaft has to be the correct length. Measure the old one and it will give you a 'ball park' figure.

WorldClassAccident · #16 26th March 2016, 14:26

WCA's Version

Get a bit of threaded steel. Drop it down the middle of the gear stick until it stops. Thread a bolt on to show where the top of the gear stick is.

20160326_140748 by WCA!, on Flickr

This is how much the shaft has to lift to get over the notches. This is resting on the stop between Park and Reverse. Surprised how little rise is required.

20160326_140809 by WCA!, on Flickr

And the news is in. The shaft has to be 11cm to reach the notches plus what ever you want to stick proud of the top of the gear stick. That is the bit that the gear knob will fix to.

20160326_140951 by WCA!, on Flickr

To be continued when I have whittled a gear stick

Nubodi Automotive · #17 26th March 2016, 14:49

That works
You may find the gear knob may move too much and be a bit floppy though.
I have a nice knob you may like
I'll bring it with me

lancelot link · #18 26th March 2016, 15:57

Quote:

Originally Posted by Nubodi Automotive

I have a nice knob you may like

chortle ...snigger ..

WorldClassAccident · #19 26th March 2016, 15:56

How to make a knob

Start with a bit of hardwood pallet

20160326_150543 by WCA!, on Flickr

Do a bit of chisel work

20160326_150549 by WCA!, on Flickr

Sand and shape it to form a delicate gear knob shape

20160326_150558 by WCA!, on Flickr

Apply some fake tan/ coloured varnish

20160326_151223 by WCA!, on Flickr

The hole in the bottom is the right size to fit snugly around the gear stick shaft while still allowing it to be lifted up as required.

The next step is to cut the threaded metal to length and then glue it to the inside of gear knob.

More photos when the varnish dries.