Home
Fixes - LAD

LAD Adjustment


Tips und Tricks zur Niveauregulierung


Woran erkenne ich, dass dieselbige eingebaut ist?

Die Niveauregulierung erkennt man daran, dass an der Hinterachse Druckspeicher (sh. Bild) verbaut sind welche das Öl für die Stossdämpfer beinhalten.


Wie kann ich die Niveauregulierung neu einstellen?

Am Stabi der Hinterachse gibt es einen kleinen Regler (sh. Bild),



der das Spiel der Niveauregulierung steuert. Wenn das Heck nach hinten geht, verändert sich die Stellung dieses Metallstücks und es wird Öl in die Dämpfer oder aus den Dämpfern gepumpt, das Heck hebt sich oder senkt sich, bis der Regler wieder in der Ausgangsstellung ist.
Das bedeutet für uns, dass wir durch verändern der Stellung dieses Reglers das Heck liften oder senken können.
Am einfachsten ist es, wir fahren über eine Grube, und lösen die zwei Schrauben leicht. Dann starten wir den Motor, da die Regulierung nur bei laufendem Motor funktioniert. Und jetzt wie gewünscht den Regler leicht nach vorne oder nach hinten drücken um das Heck zu heben, oder zu senken. Dabei nicht übertreiben und den Regler nur langsam bewegen, da die Niveauregulierung äusserst schnell reagiert. Hat man nun die Stellung, die man sich wünscht erreicht, kann man den Regler wieder festschrauben.
Allerdings muss ich darauf hinweisen, dass ein Höherlegen des Hecks eine Veränderung des Fahrverhaltens nach sich ziehen kann, daher bitte nicht übertreiben und lieber zweimal einstellen.

Niveauregulierung ausbauen?

Wer statt der Niveauregulierung z.B. ein Gewindefahrwerk einbaun will, der kommt nicht drumherum die Niveauregulierung auszubauen. Ich kann allerdings nur vom Hörensagen erzählen, wie es in etwa funktioniert, da bei mir die Niveauregulierung noch eingebaut ist.
- Ölkreislauf der Servolenkung und Niveauregulierung öffnen und Öl ablassen.
- Dämpfer abschrauben und die Löcher am Druckspeicher verschliessen (Radmutter).
- Servopumpe tauschen (sonst ist der Öldruck zu hoch).
- Und natürlich wieder Öl einfüllen



Suspension Warning

It is the control rod for your suspension leveling regulator valve. The valve controls the flow of fluid to the struts. As the stabilizer bar moves, it moves the control rod which in turn moves the arm on the regulator valve which then either lets fluid into the lines to the strut, or lets fluid out of the strut. Once the regulator arm comes back to the home position, fluid bypasses back to the reservoir.
You most likely get the error message because the regulator is out of adjustment. This means that you would have to adjust it. To do this, you really need to have the car up on a lift, with the weight of the car on the tires. You then need to load the trunk with 440lbs of stuff and then check the height of the fender above the bottom of the wheel. If the height is not correct, then you need to disconnect the control rod from the regulator and move the valve either front or back to get the desired height. Move the arm forward to raise the car, aft to lower it. Once the ride height is correct, you put a pin through the regulator body and the arm, this holds it in place in the bypass (no movement) position. Then reattach the control arm. You may need to make an adjustment to the clamp that holds the control arm to the stabilizer bar so that it fits properly into the regulator.
A poor man's way of doing this is to cheat a bit. Measure the car height (information in the Bentley on how height it should be) and then get under the car and disconnect the control arm from the stabilizer bar. Move the bar in the direction necessary and then re-clamp it. Start the car and check the height. If it is right (or close enough) then you are done, if not, try it again.
----------------------------------------
the best way to adjust the ride height in the rear is to back the car onto ramps..also the safest.
Loosen both 10mm nuts on the U-bolt on the stabilizer bar. Start the car...raise and lower the car to find the ride height you like by traversing the rod fore and aft..then tighten the U-bolt. Will take some trial an error. The good news is the LAD cannot tell if the car is on level ground...by design...so having the car on ramps will not affect the relationship of the body relative to the suspension...what you want during the adjustment process...the key being the distance from the lower lip of the road wheel to the top of the fender opening.
Congrats...your journey has almost ended.
LAD is a wonderful rear suspension.

----------------------------------------------
Re: Rear Self Level Adjustments.

I used a 10-mm wrench under the car to adjust the clamp; a couple of turns is enough to loosen the clamp. Mark a point on the clamp to the stabilizer bar as reference. The clamp only needs to be shifted 1 mm away from the reference to see a couple of inches difference in ride height.
I jacked up the car in my garage to perform this adjustment iteration, in between driving the car around the block so the rear tires regain their correct camber angle. When the car is lowered, the rear tires are jammed in a wrong camber angle so the ride height measurement is wrong.

Also, despite multiple reading I never get the idea of what Bentley tried to tell me about making adjustment with control arm in neutral position and using a rod to keep it at that position, etc. Down under the car the LAD valve is positioned so high up I couldn't see it well and could hardly reach it with my arm.

Jump to top



BMW 735i LAD suspension leak.


When my right rear shock left an oil puddle on the garage floor, I found out what new ones cost. Apparently they are not repairable.
The price of one shock is equal to the market value of the whole car.
Alternative is to convert to normal shocks, but also not cheap, as softer springs are needed.

So I decided to look into, to repair them myself. I did get all the information I could get and was trying to get another old set to experiment on.
When the left one also started leaking, I jacked up the car and took one of mine out to open up and see, what was the best way, to seal the shock absorber rod, where the oil was escaping from.
There is a light blue seal backed by an O-ring. The wiper seal would not be so important to replace, the O-ring was no problem, I did have identical ones in my assortment box. This light blue seal could be made out of PTFE and I did not know where to get this one, If I could give this seal more pressure that would do the trick. So in my box I selected another slightly bigger O- ring in section, but not to be too tight -- I would have to machine something out of the retainer.
That’s what I did on both shocks, I also had to replace the two accumulators which I bought from Febi, also the hydraulic fluid, Type M6162. at half the cost of BMW prices.

The car is on the road again and so far no leak and a much softer ride because the diaphragm of the accumulators had ruptured, the hydrogen had escaped so the accumulator was full of hydraulic fluid.

The total mileage is 285 000 Km, I have the car already for 16 years and will now drive it for many more years.

Many thanks to Erich (Schogun) he was very helpful and when I had a Question in the evening, I had an answer next morning from Japan.

The new O-ring I have used is OD 25 mm x 3.0 mm, the old one was 2.6mm in section.
I modified the retainer from 24.50 mm to 25.00 mm in diameter, depth unchanged
at 3.20 mm. That gave me 0.80 - 0.50 = 0.30 mm more pressure, it cannot be made any tighter, because the seal O-ring assembly won’t fit.

I hope this will help same other BMW owners to do the same, if they have this problem.

Regards

Roland Gehring

Jump to top



1988 750iL replace rear bump stop and dust boots.



Shogun was being bothered by an intermittant knock from the rear suspension. Since the bump stops had never been replaced we decided to spend a great spring day doing an easy task. Note: this work did not eliminate the knock but later we fixed it by replacing the left-side dogbone.

Time taken: 3.5 hours
Tools: regular hand tools, 14 mm flare wrench, spring compressors
Manpower: 2.5 guys

Start by removing the back seat squabs. Shogun has electric rear seats so each squabs are mounted on two hinges secured to the rear bulkhead by two 10mm bolts.
We found that we had enough clearance that once the squabs were removed, all three 13 mm nuts and the spring retaining nut 19mm, on top of the shock rod could be accessed.

First, pull the L/R head rest assemblies out.
Remove the 10 mm nut holding the center seat fill cushion and remove the cushion.
Remove the plastic trim pieces around the head rests -- on Shoguns car there were two phillips screws on the inner end. The outer end has a plastic clip --- you need to push the outer end of the trim piece down and then lift the plastic tongue inwards to release it.
Pull the seat belt out and slide the trimpiece down the belto that ti is not in the way.
Remove the two 10mm bolts holding the seat back.
Drive the seat bottoms foward and remove the bottoms to release the squab,
Drop the squabs foward to gain access the the top of the shock.
Remove the stiff rubber cap and then the soft rubber cap.
Secure the car, jack the rear end up and place on jack stands.
Remove the rear wheels.
Clean all areas around the high pressure nut into the lower body of the shock.
Remove the 14 mm nut and catch what ever Pentosin leaks out.
Remove the 22 bolt holding the lower end of the shock to the hub.
Put a small jack under the hub and raise the hub slightly.
Remove the three 13 mm nuts holding the top of the shock body to the mounting plate inside the car.
Slowly lower the jack while supporting the shock and then remove the jack.
Push the lower end of the shock inwards until the mounting tube clears the hub.
Lower the shock and remove from under the car.
Put the spring compressors on and compress the spring.


Remove the 22 retaining nut while holding the top of the shock rod with an 8mm open wrench.


Remove the steel plate and the top spring bearing cup with rubber pad -- mark the cup to ensure that it goes back on the same way.
Remove the compressed spring.


old versus new


Clean the shock rod and check carefully for scoring or pitting.
Reassemble and reinstall.
Start the engine and check the level of Pentosin. Top up if necessary.


Shock from the other side

Jump to top