Replacing the Fuel Gauge Sender Float

I've refitted the sender. it's the thing in the tank that tells you how much fuel you have left in the tank. the cork that makes up my float was cracked and I believed would become saturated and heavy if fitted as it was. So I fitted a new float.

The first thing to say....is that you can buy replacement modern fuel gauges with a modern, sealed float.

Modern reproduction fuel level sender for a DS

However I've read very mixed reviews of these. Some of which point to poor build quality and others that point to accuracy - though that could be as much to do with how they are set up when fitted. No. that wasn't for me. I intended to re-use my original jaeger-branded sender. I just had to find a suitable float.

I've seen some fuel gauges that were badly corroded - outside and in. I'd taken a look inside my Jaeger to make sure it didn't look like this.....

No. it looked to be in good condition. I gave the wound wire and moving contact arms a gentle clean. They are both quite delicate.

The float on the original jaegers is a rectangular box with a flat bottom. The arm hangs down in the tank and the cork floats on the fuel. As the fuel level lowers, the float lowers, altering the electrical signal back to the gauge on your dashboard.

When I removed my fuel tank I stuck an endoscope camera inside and did some tests to see how the arm and float of the sender behaved when fitted. Videos like this....

VIDEO: fuel gauge sender arm inside fuel tank

As you can see, when the arm is hanging at its lowest position ('empty' on the gauge) it REALLY is at the bottom of the tank. So 'empty' really does mean 'empty'. And I though the flat base of the float was probably significant to giving an accurate fuel level reading too.

My float was cracked and some of its shellac coating was coming off. I thought abut repainting with shellac but had read that it's not resistant to the ethanol in modern fuels. I thought about coating it with epoxy - but thought that would add weight to the float and alter its buoyancy. So I was on the lookout for a float solution.....

I'd seen plain, uncoated cork used.

(Credit: Jarno Muona)

I'd seen people replace the float with bits offcuts of closed cell foam - and that seemed to work.

Float made from closed cell foam

The Jaeger float is held on the arm only because of a wobbly section at the end and so a piece of foam is perhaps a good substitute if you're keeping the original arm.

And I'd seen some carefully made metal floats.

Homemade metal float (credit: Buttercup Bob)

Several years ago someone on Facebook found a cheap float on eBay and used the float off that. 

Modern plastic float (credit: Simon Broadhurst)

I bought one as well and squirrelled it away. More recently, I thought it wouldn't hurt to see if I could find a different sender float of about the same shape and size as the old Jaeger - with a flat bottom. And I found one! The float was about the right length.

And it was about the right depth. And used a slot in the end to stabilise the float - just like the cork original.

I thought about trying to bend and re-shape the long arm that came with it for use on my Jaeger, but found it just too thick to pass through the hole in the sender.

So I also bought some more sprung steel wire - the same size as my Jaeger arm - to make a new arm. Removing the Jaeger arm and cork was just a matter of opening up a couple of crimps. They were all that held it on.

I was careful to engineer the new arm so that - when fitted to the Jaeger, it hung down the exact same amount as the old cork float. 

Setting the arm length and height

I was really pleased with the result. But I'd forgotten one tiny detail..... the float was too big to fit through the hole in the fuel tank! It was too wide! So, ultimately, I've had to resort to using the 'barrel' float that I'd bought previously. 

Again I was careful to set the arm length and height so that 'empty' really does mean 'empty'.

I've refitted it in the tank now. New seal and a good earth contact.

The sender will end up sealed in the 'time capsule' under the seat, but I suspect I will still keep my eye out for a suitable modern sender unit - but with a smaller float.

Setting The Height Corrector Linkages

Unfortunately, at this stage of the restoration I couldn't fully complete the adjustment of the ride height the car. That has to be done up on a lift or down in a pit - measuring  - and adjusting - the road clearance from the underside of the car. It's dangerous to do without a lift or pit. More importantly, it has to be done with a full weight car - including (according to manual 518) its spare tyre, tool kit and 5 litres of fuel in the tank! My car hasn't yet got doors, bonnet, boot lid, roof or seats - so I'm not at that stage yet......What I could do though, was 'pre-adjust' the heights and set up the manual height linkage. So I did!

In very simple terms, the height correctors help to maintain the vehicle road clearance at a prescribed (set) height. They play no part in maintaining the Ds legendary smooth ride over lumps and bumps. Those movements happen too rapidly for the height correctors to play a part.

I wrote about my understanding of height corrector operation HERE. A key point to take away from that earlier post, is that there is a ball on the end of the height corrector slide valve.....

Operating ball on a height corrector

It is screwed to the end of the slide valve that moves within the height corrector. When the height correctors are fitted to the car, those balls sit in cradles - or forks -  attached to rods that are connected to the anti-roll bars. 

This photo (of a rear height corrector) shows the rod, its upright fork and the ball on the height corrector. The front configuration is essentially the same though looks a little different.

Control rod fork on height corrector ball

Note also the rod linkage above the ball of the height corrector - at the top of the fork. The settings of the height correctors can be varied in two ways. Firstly there are the control rods to the anti-roll bars of the car. Movement of these directly cause the fork sides to press on the height corrector balls and so move the slide valves.

Secondly there is the manual height lever in the cabin. Through an arrangement of rods and links....

Manual height control linkages.....

.....the lever artificially moves the forks to press on the balls to force the height corrector slide valves into different positions. This then causes the suspension - and the height - to react.

The height lever moves a system of rods to the height corrector forks

Although when you move the lever in the cabin you move it maybe 12cm top-to-bottom/ high to low, the actual movement the rods and forks cause to the slide valves is only a tiny bit by comparison - just a few millimetres of slide valve movement are needed - as this photo of the grooves on the slide valve shows. 

The slide valve moves, and the grooves allow or prevent fluid flow

Setting the height is all about the accuracy of setting up those forks - front and back - relative to the height correctors and about the accuracy of setting up the manual lever linkage.

Pre-Adjusting The Suspension

The first job was to pre-adjust the front and rear heights. The instructions for this can be found at operation D.430-0 in volume 1 of manual 814. You will need to make something that passes as tool MR 630-51/3.......the drawing and measurements for what that looks like can be found in the 'special tools' section at the back of volume 1 of 814.

Basically, the tool is two straight rods of a certain length, and you measure the distance between them.The proper tool is made of 14mm diameter steel. The shorter tool is taken down to 12.5mm diameter for 15mm length. the longer tool is taken down to 13.5mm for a minimum of 100mm. 

I hunted around and found some tube that was the right diameter for the shorter rod and found a long thin rod which - with a sleeve made from a piece of fuel hose - came up to the right diameter. I used red tape to mark the critical lengths.

My version of Special Tool MR 630-51/3.....

This is the technique I followed for pre-adjusting the front suspension. The car was already supported on axle stands and with the front wheels removed. Under the car - within the tunnel across the engine bay - I loosened the clamp on the control rod on the anti-roll bar. My clamps still have screws with special heads - but I have a special socket that fits.

Control rod clamps on the right - with special headed screws....

Anti-roll bar - with the control rod and it's clamp attached

I had loosely assembled the manual linkage back to the height lever area - but the height lever wasn't fitted yet. If that linkage is all connected up, you need to put the height lever in its 'high' position. I used a screwdriver blade to push the ball on the height corrector spindle fully forward. 

Using a screwdriver to lever the slide valve fully open

It's important to be careful not to tear the rubber on the height corrector when you are doing this! In this position, the height corrector is in its 'fully open' position - consistent with the height lever being put in the 'high(est)' position. This next step was where the tool I made got used. On the right hand side of the car, I fitted the short tool in the round hole in the middle of there hub....

Short tool inserted 15mm in the hub hole

....and I fitted the long tool in the hollow bolt that is used to fit the steering relay to the chassis. The fuel pipe sleeve on my homemade tool was just the right size and the tool was a snug fit. It didn't hang at an angle.

Long tool inserted 100mm in the steering relay bolt

I used a jack under the bottom hub ball joint to raise the hub - and so the arms - and so the anti-roll bar - until the gap between the two tool parts was 185mm.

Using a jack to raise the hub

Measuring the distance between the two tool parts - 185mm

I left that jack there and then moved the tool parts to the left hand side of the car. I fitted the tool parts as before and used a second jack to raise that hub until the gape between the tool parts was also 185mm.

Measuring the distance of the left hub

It's very hard to tell, but I made sure that there was a small (1mm) gap between the back of the fork of the control rod and the ball of the height corrector slide valve - back where the blob of grease is in this photo.

The ball should not touch the back of the fork

Fork of the front height corrector control rod

Basically - the back of the fork shouldn't interfere with the ball. If they do touch, then the control rod on the anti-roll bar needs to be slid a fraction inwards. Happy that there was a very small gap, under the car I tightened the clamp of the control rod on the anti-roll bar in that position. That was it - and the jacks could be removed. 

Just as well - because I needed them again. The rear is easier to set. Again, with the rear of the car on axle stands, and the control rod clamp on the anti-roll bar loosened....

Clamp for the rear control rod

...I used the jacks to raise the two suspension arms such that the gap between the flat face of the bump stop plate and the rim of the cup that holds the bump stop rubber was 35mm. I found it easiest to use a strip of card to make a 35mm wide gauge  - and used that to check the gap on both sides.

Setting the gap at 35mm

Once I had the gaps on both sides of the car at 35mm, I pushed the fork forward to put the height corrector in its 'fully open' position. No need for a screwdriver here - you can just use your fingers. Press hard.

Pushing the rear corrector into it's 'fully open' position

With that done, I tightened the clamp on the anti-roll bar. The jacks were removed and that was the process for pre-adjusting the suspension. At this point, I should have moved on to the final and more accurate setting of the height - the bit involving pits or lifts and a fully laden car. I couldn't do that, so just took my initial 'pre-adjustment' set up as the start point for the next step - setting up the height lever and mechanical linkage.

Connecting The Manual Height Lever Linkage

Whereas the 'pre-adjustment' was done with the car in it's 'high' position, the linkage is then set up with the height lever in the 'normal' height position.

There are two link rods connected to a relay lever under the height lever. A short link rod runs forward through into the front wheel arch and a very long link rod passes rearward through the sill to the rear wheel arch. The link rods are adjustable: at the lever end, both rods have flattened ends with a series of holes through them. A pin clip goes eventually goes through both rods (and the height lever).....

A pin clip locks the two link rods together

.....to hold the rods in what ever combination of holes is appropriate relative to the  'normal' height position of the lever. So what combination is appropriate?

Attaching the Height Lever. In the cabin - and being a Pallas car -  I first threaded the end of the height lever through the Pallas trim and then through the quadrant (the curved part with slots and marks for the height positions). And THEN, through the pinch bolt hole of the relay lever.

Then I locked the forked end of the relay lever over/ around the height lever, and then located the end of the height lever in the two holes in the side panel bracket.

The lever locates in a second hole in the side panel
(credit: Emanuele Ragnetti)

With the height lever in place, I located the relay lever pinch bolt over the bracket of the side panel...

....and tightened it so that the height lever could not pull out of its hole. With the height lever fitted, I set it in the 'normal height' position. I then moved on to tackle the two link rods.

Rear Link Rod. I threaded the long link rod for the rear height corrector in from the front of the car. I fed it through the hole in the bulkhead (where the shorter rod will eventually go), and down through the tunnel into the sill beneath the height lever.

Tunnel on the sill face - beneath the height lever

From there I guided it through some white nylon guide bearings high up inside the sill. 

Front to back - rear link rod passing through a greased bearing

The threaded end went as far as just inside the rear wheel arch, where I reattached the threaded yolk.

Yolk  - for the end of the link rod

The yolk connected to a 'Z' shaped torsion rod. I fitted that and temporarily secured it in the yolk with a new bifurcated rivet.

Torsion rod connected to the yolk

The torsion rod rests in two cradles and is held there by a folded tab. 

A folded tab keeps the torsion rod in it's cradles

Viewed from above, the other (top) end of the torsion rod and the control rod connected to it, need to be in line with the slide valve and ball running through the height corrector.

The short rod (centre) needs to be in line with the height corrector

To adjust the angle of that rod, there is a collar with a pinch bolt on the torsion rod to set and lock it's side-to-side position.

The collar and pinch bolt set the sideways position

So.... with the torsion rod in place, to decide which hole to use at the height lever end, the end of the 'Z' shaped torsion rod at the height corrector end needs to be set such that there is a gap between the torsion rod and the rubber dust cover of the height corrector - this gap here.

The gap needs to be about 8mm to 9mm. Don't forget that this is being done with the height lever in its 'normal' position. That gap ensures that when you move the lever to it's lowest setting, the torsion rod doesn't touch the height corrector and prevent the slide valve fully moving to it's 'exhaust' position.

Anyway, to adjust that distance, I removed the bifurcated rivet from the lower yolk joint - the one on the link rod, disengaged the torsion rod, and wound the yolk on or off as necessary, then re-engaged the torsion rod. 

Now....if trying to remove or adjust that yolk as just described, be warned: that threaded end of the link rod gets very rusty. I tried to unscrew that yolk to remove the rod for sill repairs and snapped the yolk and end of the long rod off! You can see what I did to repair it HERE. I had to ask my mate Peter to make another yolk.

My yolk was so rusted that it snapped off!

To hold that gap at 8mm to 9mm, I temporarily slipped something of that diameter in the gap. Back in the cabin I pulled the rear link rod forward to take up any slack, and then chose whichever hole in the flattened rod end best lined up with the height lever/ relay arm (in it's 'normal ' position remember) and temporarily pinned it like that. 

Pin clip temporarily fitted to (both) link rods and relay lever

Do NOT be tempted to fold the pin clip completely around the rod. You still need to fit the front link rod and - even after that - are bound to need to remove it again and it will only take so much bending and straightening. 

Front Link Rod.  The short front link rod has a hooked end (top of the photo below) that connects to the top end of a 'Z' shaped torsion rod by means of another collar and pinch bolt. 

Hooked end of the link rod and collar (top)

Detail - the collar traps the torsion rod on the link rod

With my suspension and pipework already fitted, I was just about able to wiggle that torsion rod and yolk into place around the hydraulic pipes and onto its cradles.

Cradles and folding tab to secure front torsion rod

Like at the rear of the car, a folded tab then keeps the torsion rod in place. 

A folded tab secures the torsion rod in it's cradles

At it's other, lower, end that torsion rod has a threaded yolk fitted. It's held on by a bifurcated rivet. The lower end of that torsion rod and the yolk are tucked away right down the back behind the suspension unit. Nearly impossible to see. 

Nearly impossible....

Yolk on the lower end of the torsion rod

As you can see in the photo below, the yolk has to line up with (in fact pass through) a hole through the suspension unit. 

The yolk enters a hold in the suspension housing

Another collar and pinch bolt on the torsion rod (at the bottom in the photo below) sets the side-to-side position of the torsion rod - and so helps you line up the yolk with the hole.

The bottom pinch bolt sets the position of the torsion rod

In deciding which hole of the short link rod to use at the height lever end, the task is to set the gap (as measured at the yolk) between the torsion rod end and the suspension unit. This gap here.

It needs to be about 8mm. The gap is necessary so that when the height lever is put at it's highest setting, the torsion rod does not contact the suspension arm and stop the slide valve fully opening.

I set that gap by resting something of 8mm diameter (I think it as a socket extension?) in the gap above the yolk and then  - from within the cabin - pulled the torsion rod against it to take up any slack. I then chose whichever hole in the short front link rod lined up best with the height lever when in it's 'normal' position. If finding that position would mean having a gap of less than 8mm, then you can instead slightly alter the position of the quadrant - in other words slightly alter the position of the 'normal' height position.

The quadrant is secured in slots -
meaning there is some adjustment to the gold relay lever if needed

Be aware though that if you now move the quadrant.....you may need to go and check that the gap at the rear height corrector is still 8mm to 9mm. And may need to adjust the yolk on the rear link rod again....

Once I was happy with the front gap (and still happy with the rear) I temporarily refitted the pin clip through both rods and the relay lever again.

Pin clip temporarily over the relay lever and link rods

I resisted the temptation to bend the tab around the clip to close it until I completed the rest of the set up process. Nearly there now......

Setting The Linkage At The Rear Height Corrector. The rear torsion rod has a short rod connected to it that passes over the top of the height corrector and through the hole in the fork of the control rod. The end of that short rod is threaded and has a special nut/ sleeve and locking nut.

Special nut and locking nut

When the height lever is in it's 'normal height' position, and when the fork (and so height corrector slide valve) are pressed fully forward, that nut and lock nut should be adjusted so that there is still a small gap between the locking nut and the fork. In other words, the position of the locking nut should not prevent the fork/ slide valve moving fully forward.

Similarly, when the fork lever is pressed fully back, there should be a small gap between the fork and the hex of the special nut - the position of the special nut should not prevent the fork moving fully back. I fiddled with the nut and locking nut until I was happy they met these conditions then tightened the locking nut.

Setting The Linkage At The Front Height Corrector. Setting the front is similar to the rear but a bit more fiddly due to restricted access. A short rod is threaded through holes in the suspension arm and joins to the yolk of the torsion bar with a lock nut.

A short rod joined the yolk

That rod needs to be centred in the holes - which is where that earlier bit about centring the yolk in the hole comes into play. The forward end of that short rod passes through a hole on the fork of the front control rod where there is a special nut and lock nut.

Special nut and lock nut on the front fork

When the fork is pushed fully forward, there should still be a small gap between the fork and the hex of the special nut - the special nut should not prevent the fork being pushed fully forward - and so the slide valve fully opening.

And when the fork is pushed fully back, there should be a small gap between the fork and the locking nut. The position of the locking nut should not prevent the fork being pushed fully back. 

That was just about it. I put the wheels on the car and let the hydraulic pressure build. Then, for the first time since what? 1999? I moved the car through its five height positions. Much to my relief - and great surprise - it responded correctly and set itself in the five positions. I needed to put the car on jacks again to adjust the special nut on the front corrector - just so that I was happy with the clearance of the nut on the fork, but other than that I considered it 'job done'.

That isn't really the case of course, as I haven't yet fine-tuned the vehicle height fully-laden and over a pit etc. That might mean I need to tweak the set up a little. for that reason I haven't fully split the bifurcated rivers on the yolks, and I haven't finally folded over that tab on the clip at the height lever.......