Hi, my adjustable pedals are not moving. When you move the joystick towards the driver, all you hear is a "thump". When you move the joystick towards the dashboard, it does not do anything nor make any sound. Either case, my pedals are not moving.

2006 S-Type R

Anyone else have a problem like this or solution?

Thanks,
Frank

 

Pedals are not adjustable on the stype

 

Jochem00 wrote "Pedals are not adjustable on the stype"

-Actually many of the late model -Types do have adjustable pedals, like in my STR.

However, I have scoured the forums and there seems to be limited complaints and unfortunately no solutions. I would hate to spend the $650 quoted to get the whole assemply repalced.

Thanks,
Frank

 

Mine has the adjustable pedals, too.

 

My STR has adjustable pedals, and are also inoperative in the manner described by OP.

I remember searching this subject as well, and read somewhere on the forums about a simple fix, (could have been one of brutals posts) I never really looked at it though as it doesnt bother me too much,

I have a habit of playing with the adjustable pedal switch from time to time; all you get is that 'thump' from the pedal box. Go figure, through enough time spent parked, playing with the adjustment over the year, the pedals started moving... now I have SOME adjustment, but seems to have a pretty small range so I figure its still jammed in some way.

 

I have investigated this.
My pedals stopped working, even though the brake adjuster is separate from the accelerator adjuster.

The brake adjuster uses a double worm drive to move the pedal forward or back. A motor separate from the brake assembly is attached by a drive cable to the double worm drive assembly. Because of this, you can replace just the motor, or just the brake pedal assembly.

Anyway, in the double worm drive, the motor spins a worm that turns a gear, that pulls a worm through itself. Additionally, the force you push on the brake pedal is transferred through the double worm drive to the rod on the brake booster.

So what happens and why does it fail?
The double worm drive does not have any limit switches, just hard stops. So when the pedal comes to the end of motion, it just loads up on the gears and motor. When the pedal is moved to the forward position to the hard stop, and then you press on the brake firmly (really hard, like slamming), you wedge the gear against the hard stop. Now it is not possible to move the pedal because the motor and first worm cannot create enough torque to unseat the gear from the stop.

HOWEVER, they do create enough torque to crack the gear, which is made of a substandard plastic.

Sadly, the gear is the only part that needs to be replaced, but is unavailable as a single part. To remove the gear you must grind off a rivet which is the rear end of the second worm. This would have to be re-riveted some way.

A temporary fix is to remove the black cover over the double worm drive (two screws) and manually tighten (yes tighten), then loosen the gear from the hard stop. Do not do this by turning the gear by the teeth as you will completely break the gear (what happened to me). Instead, turn the shoulder of the gear. Once it is loose, you can spin the gear to the mid position, put the cover back on, and leave it alone. Yes, you can adjust it now, but know that if you go to the hard stops, you might have to do this all over again. And the crack in the gear is getting bigger and bigger.

The replacement brake pedal assembly is about $200 from Gaudin, and that will be my summer project for the Jaaag.

Notes:
1. You have to tighten the gear before you loosen it, because it has deformed the rivet. You have to tighten just a very tiny amount to deform the rivet a little more to give yourself some micro-lash to enable the gear to be loosened. You have heard of slightly tightening a bolt, before you loosen it. It is an attempt to lessen or remove pre-load on the bolt.

2. The gear has a metal core with inner teeth for the second worm, and outer plastic teeth for the first worm. The interface between metal and plastic is a friction fit.

3.The thump is the drive cable slapping to one side under load by the motor.

 

FINALLY some answers..thanks for the detail heima.

Do you have an exact part number and do you know how difficult of a swap this might be ? I will be looking to fix this thing once and for all.

Thanks!!!

 

For Left hand drive its part number XR853896 and the price has gone up to $226 at Gaudin. Dammit! Knew I should have ordered it by now. Hmm, at OEMonlineparts.com its $193. That price has increased as well. Thanks Jaguar. (spoken with sarcasm)

It looks like 6 bolts/nuts secure it in place. I do not know how it attaches to the brake booster shaft. You will also have to transfer some switches over from the old assembly to the new assembly.

When you replace it, you will most likely be lying on your back looking up under the dash.

The part is 1 in this picture. The arrow is pointing at the double worm drive and the tip of the arrow is where the drive cable from the motor inserts.

 

Thanks for the details. Anyone else have access to electronic shop manuals that might explain how to do this swap?
Thanks,
Frank

 

One quick question, what do you mean by the shoulder of the gear, exactly?
Thanks,
Frank

 

The gear is a two part assembly. The metal core with inner teeth, the outer plastic "ring" with outer teeth. To manufacture this gear, the metal core was made first, then the plastic outer was molded on.

The metal core is wider than the plastic outer, so it has a "shoulder" in comparison to the plastic outer.

When I first saw the gear, I mistakenly thought the metal core was the hard stop. It wasn't until I spun the plastic outer on the metal core, discovered the crack and saw the metal core in the crack that I realized the gear was actually two pieces.

I used a pair of needle-nose vice grips to grab the metal core of the gear at the shoulder, tweek it tighter, then loosen the gear.

 

Jag944 - there's JTIS on here. If you're expecting anything to go into this sort of detail then you're headed for disappointment since they probably expect any shop to replace the whole assembly.

There's also jag's TOPIx and other sites such as AllData / Mitchell.

 

Mine are non opt too. They just click once in each direction. I've hardly ever used them so it's not an issue but I find it rather improbable that they're actually mechanically broken given such little use.

I don't really care but I always though it was some sort of a lockout feature that's permanently stuck on? Maybe it mistakenly thinks I'm driving the car and doesn't want me to operate them?

The ones on my 2001 Sable with 150K miles still work and I hardly use those either.

 

You are probably correct.

I believe mine broke under this scenario:
Owner has long legs, so pedals are adjusted all the way to the front of the car. The gear is against the hard stop.
On repeated occasions, the owner slams on the brakes. Each time, the gear is forced even tighter against the stop.
Owner sells car to me. I have short legs. I try to bring pedal closer, but just hear a thunk in one direction, nothing in the other. I dismantle the double worm drive and see that the gear has deformed the rivet.

You know the rest.

 

Guys, I have the issue , I did write about it on another thread https://www.jaguarforums.com/forum/x...p-64906/page3/

But basically on my XJR X350, the gear is METAL, no plastic on it, and it cracked also. The worm drive is only able to go one rev, either one or the other way, it means the pedal moves back and forward but only like 1". I took the plastic cover off, and turned the gear manually , because my KNEE hurts when the pedals are not all the way towards front. I then assembled the plastic cover back again.

 

If someone has a picture of this pedal gear, I may have the fix. I make a gear to repair Ford Panther platform cars and it fits the XJ8, so it's possible that it will fit the S type as well.

 

Yes all STR's had adjustable pedals and if you have long legs and put the adjustable pedals all the way forward towards the firewall they will break and lock up solid.

It's a well known problem due to the cheap plastic gear assembly as posted above.

I think heima has covered most of this in his post but attached is the instructions/explanations from the Lincoln LS side which of course suffers from the same problem. Might even be the same post?

It does look like Jaguar fixed this because my newer 2014 XJR does NOT have adjustable pedals and it has just about everything else possible!
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The gear does not crack due to slamming on the brake pedal. If you take the brake pedal assembly all apart you can see that the only thing the gear does is set height of the pedal, the pressure from your foot does not directly affect the gear. It breaks due to the difference in thermal expansion of the plastic around the outside of the gear and the steel threads on the inside. It always cracks at one of the three dimples left from the injection molding process. At any rate, my gear would eliminate both issues. If I can help you guys out with this issue, I'd love too!

 

Years out of date thread. Problem seems extremely rare.

 

Well it does seem that they only get stuck if you run them all the way adjusted forward and leaved them there. But that's where I have always had them too.
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