Thule step stops working

[BruceM]

If it’s metal to metal then if it were me and the screws were stiff I’d blowtorch them hot - a hairdryer is not hot enough, then rapidly cool with a wet cloth. Then repeat. You’d want the screw to be almost red hot. After that bolts and screws usually undo quite easily. The same technique is commonly used on brake bleed nipples. Given that the cross head is mangled I’d use mole grips on it to unscrew and then replace all the screws with new.

[Derek Uzzell]

Peter

 

On Page 87/99 of the document on this link

 

http://www.motorcaravanning.co.uk/pdf/2017_Thule_Step_Spares.pdf

 

there’s a spare parts list and drawing of a Thule slide-out step for a 2016 Ducato. (Copy of drawing attached below).

 

My 2015 Ducato-based Rapido has a Thule slide-out step and in 2019 was damaged by ‘road furniture’, badly bending the flat metal plate through which the step slides (the part clearly shown in your photo) and totally jamming the step closed.

 

My Rapido’s step has a very different bracket arrangement to yours, but I was able to gain access to the step’s interior by removing parts from the step’s front followed by removing the ‘lower protection’ cover (Part 10 on drawing). So, if you just want to check the guts of the step, you may be able to do this without actually taking it off the motorhome.

 

(On the other hand, as you’ve mutilated one of the 5 bracket screws, it might be wise to follow Bruce’s advice and get the step off.)

 

[peterjl]

Hi

 

Thank you for your ideas.

 

I thought about a blow torch but it’s set right in next to paintwork which I didn’t want to damage. Also, because it’s set back I cannot gain access with molegrips.

 

I have also looked at gaining access with it in situ. The front plate comes off but the step has a stiff rubber seal underneath and I can’t get the plate over. There are two screws each side of the step in the vicinity of the seal but I am not sure if that releases it. It’s not shown on the diagrams on the net so I am nervous of just taking screws out.

I did wonder if it’s possible to cut a slot in the screw but I have still got to be able to move it.

 

Peter

 

[Derek Uzzell]

peterjl - 2020-11-12 7:02 PM

 

...I have also looked at gaining access with it in situ. The front plate comes off but the step has a stiff rubber seal underneath and I can’t get the plate over. There are two screws each side of the step in the vicinity of the seal but I am not sure if that releases it. It’s not shown on the diagrams on the net so I am nervous of just taking screws out...

 

Peter

 

I’m guessing that you and I have the same Thule step - the SDA 616-00 model shown on Page 89/99 of the spare-parts document I provided a link to above.

 

The “stiff rubber seal” you mention is arrowed in red on the drawing attached below and (when I worked on my step) although getting the front plate over it was not easy, it was doable.

 

Your photo doesn’t show clearly which of the three bracket-screws now has a damaged head, but if you feel you cannot protect the paintwork adequately to risk trying the blowtorch ploy, and you cannot move it (say) using a centre-punch on the head’s edge and a hammer, you’ll just have to bite the bullet and use a drill. If you are careful and start with a small-diameter drill you may be able to get the head off without overly damaging the thread of the hole that the screw goes into and (once the step has been removed) be able to get the now-headless screw out. Or, if the thread in the hole has been lost, you might either re-tap the hole and use a larger screw or use a nut-and-bolt (assuming that would be practicable).

 

In order to address the damage I mentioneed earlier I had most of my Rapido’s step apart including Parts 3, 5, 6 and 7 on the drawing. And I know I accessed the motor unit as I discovered that the end-fittings of the operating arms (Part 8 on the drawing) had been insufficiently tightened when the step was manufactured. I don’t recall having any heart palpitations when I was removing the screws (or afterwards), but if you are anxious about reassembling the step, take photos at each disassembly stage.

 

As your step’s bracket-screws are star-headed and the screw that’s stuck wouldn’t undo even though you used enough torque to burr the head, even if you manage to slot that screw’s head it’s unlikely that you’d be able to undo it afterwards with a ‘flat head’ screwdriver.

[peterjl]

Thank you Derek. That’s very helpful.

 

I had not thought of a centre punch and hammer, I will give that a go.

 

Re getting the front off over the rubber seal, because the step is in tight the seal it up tight against the plate and there is not the space to work the plate over the seal. That being said I will try again.

 

I am just off to try and source replacement screws and nuts.

 

I will report back

 

Regards

 

Peter

[BruceM]

peterjl - 2020-11-12 7:02 PM

 

I thought about a blow torch but it’s set right in next to paintwork which I didn’t want to damage.

 

Re use of the blowtorch. Kitchen baking foil makes an effective heat shield if you have the space to position it. Ideally two to three layers. It’s standard to wrap the flexible brake pipes in it when blowtorching the bleed nipples if they’re too close. Wood is also a good insulator – although it will burn so wrap in baking foil first. Sometimes shocking a bolt with a hammer can be enough to loosen any corrosive binding although in my experience rapid localised heating and cooling where possible is the only reliable and least destructive approach. Failing that I’d concur with David’s approach. One thing I’d add, when you come to reassemble I suggest you grease the bolts, some future person will thank you for it.

[Brian Kirby]

I think I'd be inclined to just drill off the head of the machine screw using a drill that is slightly larger than the threaded part of the screw. As you have the other five screws it should be easy to take the size from one of these. You'll soon know when the drill has advanced sufficiently as the screw head will begin spinning on the drill. The remaining portion of the screw should unscrew with the aid of a Mole wrench once the step is out. You should be able to find similar, Torx (I think) head screws from on-line suppliers. I'd go for stainless, and replace all six - just in case.

 

Word of caution! Make sure the main step fuse is pulled before trying to do anything inside the step. It may only be 12V, but the motor is powerful and reacts quickly, and those "lazy tongs" extenders are very powerful. Think fingers, and amputation!

[Derek Uzzell]

I notice that there's a YouTube video that describes how a Thule slide-out step is fitted to a Ducato van and this shows the 6 dome-head screws.

 

 

It looks like - if the head of the reluctant screw is drilled off and the remaining 5 screws and the 2 bolts at the rear of the step are all removed - the step can then be taken off and the horizontal 'bracket' into which the 6 screws appear to go will also be easily removable. And when the bracket is off, it should be quite simple to remove the now-headless screw from it.

[peterjl]

Thank you for all your support on this.

 

I have managed to source replacement screws albeit not with a star head but a Phillips, so I shall replace all the screws with greased new ones.

 

I also sourced replacement nuts.

 

I have also seen the video which does help.

 

I now have to wait for some dry weather.

 

I will keep you posted.

 

Peter

[Derek Uzzell]

There’s actually another YouTube video

 

 

that’s a lot longer and goes into much more detail regarding how the step is fitted to a Ducato van.

 

Each screw goes through an external ‘plate’ (there are two plates and one is shown in Peter’s earlier photo). The screw then passes through a hole that needs to be drilled in the bottom of the van’s ‘skirt’, and the screw finally enters a hole in a (cast aluminium?) fitting (arrowed in attached photo below) that is bolted on to the step’s side.

 

Torx or socket button-head screws in stainless steel aren’t that difficult to source on-line (examples here)

 

https://www.westfieldfasteners.co.uk/ScrewBolt_M.html

 

https://www.ukstainless.co.uk/catalogsearch/result/?q=button%20screws&gclid=EAIaIQobChMImMXm2ZOA7QIVQ-7tCh2gmgQgEAAYAiAAEgIcv_D_BwE

 

https://www.spaldingfasteners.co.uk/m6-a2-stainless-steel-torx-button-machine-screws/

 

though delivery charges can bump the price up significantly for small orders.

[Keithl]

Halfords, Screwfix and ToolStation all stock stainless screws, washers and nuts in small quantities.

 

Keith.

[Derek Uzzell]

That’s true, but if Peter wanted exact (ie. Torx-head) replacement bolts in stainless steel, obtaining them from an on-line specialist stockist should still be fairly inexpensive.

 

For example a pack of ten M5 A2 stainless steeel Torx button machine screws with a 16mm length would cost £4.33 (including VAT and postage) from Spalding Fasteners

 

https://www.spaldingfasteners.co.uk/m5-a2-stainless-steel-torx-button-machine-screws/

 

(I'm assuming that the 6 fasteners for the Thule step are ‘machine screws' rather than the self-tapping variety.)

[peterjl]

Ok. Now you have me worried that I have the wrong replacements.

 

I assumed they were self tappers, I went along to a specialist shop, Orbitak Fasterners in Watford, and said I wanted 6 of these - showing them one I had taken out. They had some with a posidrive head. I have no idea wether the existing and new are stainless or some other material.

 

How do i tell?

 

How do I know the thread? The existing ones have pointed sharp ends like screws not flat like bolts.

 

Confused of Amersham

 

Peter

[Keithl]

Pointed ends are more likely self tappers so whoever fitted the step cheaped out and just drove the self tappers into the pinch weld of the sill instead of drilling through and putting nuts on the back. You should be ok to replace like with like.

 

Keith.

[Alanb]

I am surprised that Ebay has not been suggested, as a source of supply.

 

10 off M5 x 16mm Torx Pan Head £2.80 delivered, see here.

 

The Omnistep on my PVC is mounted by means of a length of aluminium angle (50x50x4), which is secured to the sill by 3 x M6 coach bolts, and to the step by an M6 bolt at each end. The inboard end of the step cassette is further supported by a vertical hanger from a chassis cross member. Quite a simple arrangement, with no special fitting cradle.

 

All nuts and bolts were changed to stainless steel and greased when the vehicle was new.

 

A possible way to heat the screw would be to use the red hot poker technique. While not as effective as a torch, it would be less hazardous.

 

Alan

 

 

 

 

[Derek Uzzell]

Keithl - 2020-11-14 6:36 PM

 

Pointed ends are more likely self tappers so whoever fitted the step cheaped out and just drove the self tappers into the pinch weld of the sill instead of drilling through and putting nuts on the back. You should be ok to replace like with like.

 

Keith.

 

If you look at the photo attached to Peter’s posting of 12 November 2020 2:44 PM, compare it to the image attached to my posting of 13 November 2020 6:39 PM, and wade through the YouTube video I provided a link to in that posting, you’ll see that the step ‘kit’ fitted to Peter’s Globecar is a Thule SDB 613 (Page 104/120 - SLIDE-OUT STEP 12V 2016 DUCATO on following link)

 

http://www.etriddiough.co.uk/pdf/12.pdf

 

The 6 screws that Peter has referred to pass through two plates (3 screws for each plate) then pass through holes that the installer must drill in the Ducato van’s sill. On the inner side of the sill opposite each plate a spacer (that is eventually clamped against the inner side of the sill) is placed. The screws pass through the spacer and then enter pre-drilled holes in an L-shaped fitting bolted to each side of the step’s cassette. (Fittings arrowed in image attached below)

 

The reason I queried whether the 6 ‘screws’ were machine screws or the self-tapping type was because - if the 3 holes in each of the two L-shaped fittings had been internally threaded to accept machine screws - the manner in which the installation had been carried out on the YouTube video would have seriously risked damaging those threads. So (having thought about the You Tube video more carefully) it seemed much more likely that self-tapping screws would be used.

 

As Peter has been able to remove 5 of the 6 original screws and has now described them, it’s clear that they are self-tappers. Orbital Fasteners (OF) were given sight of the original screws, so should have been able to match their dimensions (and should be able to provide Peter with that information). Stainless-steel button/pan-headed Posidriv self-tapping screws are available, but OF may well have not supplied stainless screws unless specifically asked. To confirm if the screws OF supplied are suitable, Peter can just try (carefully) screwing one into one of the 5 ‘empty’ holes in the sill.

 

The guy in the YouTube video said that he drilled 6mm-diameter holes through the sills, so the screws MIGHT be Number 12 size that have a 5.5mm thread diameter - or they MIGHT be Number 10 size that have a 4.8mm thread diameter.

 

https://www.spaldingfasteners.co.uk/no-12-a2-stainless-steel-pan-torx-self-tapping-screws/

 

https://www.spaldingfasteners.co.uk/no-10-a2-stainless-steel-pan-torx-self-tapping-screws/

 

Long-term, stainless screws (well greased) would be best and a Torx head better than a Pozidriv one, but as long as the OF-supplied screws match the originals and are well greased when the step is put back on, they should be adequate and (if so wished) could be replaced with equivalent stainless Torx screws at some time in the future.

[peterjl]

Hi. UPDATE

Two steps forward one step back

 

Following Brian’s suggestion I drilled the head off the screw and removed step.

 

Nothing obvious jamming the step.

I looked at the wires, two are fairly easy to access and two are v difficult ( these two go into a box where the step retracts onto a pressure switch.

The two I could access, the wires were tightish and not sure how to access, remove. See photo one

I moved the wires when looking, then reconnected power and step worked briefly. Waggled orange wire and step worked. I had my wife operates switch whilst I waggled wire with pliers and step worked all the time. After a while I still could not replicate fault. Ie step is working. The orange wire had been touching one of the arms that move so I have moved it away.

 

Next I tried to remove the remains of the screw see photo 2.

 

You can see part of the thread for whole length of the screw so it is easy to dowse in penetrating (3:1) spray.

Tried mole grips, to get it tight a used pincers on the tightening screw, but no luck. It’s well and truly stuck.

 

I am thinking that I might try a blow torch next cos, whilst I haven’t disconnected I ca move it from vehicle.

 

Peter

[Derek Uzzell]

peterjl - 2020-11-15 2:57 PM

 

..Next I tried to remove the remains of the screw see photo 2.

 

You can see part of the thread for whole length of the screw so it is easy to dowse in penetrating (3:1) spray.

Tried mole grips, to get it tight a used pincers on the tightening screw, but no luck. It’s well and truly stuck.

 

I am thinking that I might try a blow torch next cos, whilst I haven’t disconnected I ca move it from vehicle.

 

Peter

 

If I were attempting to remove the headless screw (and assuming the bracket that holds the screw is alloy) I’d start by filing/grinding a couple of ‘flats’ on the part of the screw that protrudes from the bracket so that it becomes possible to get a really firm grip on the screw with a mole wrench.

 

I’d warm up the part of the bracket where the screw is stuck and then twist the screw sharply clockwise with the wrench to break its grip on the bracket (rather than initially try to ‘undo’ it by turning it anticlockwise). Once the grip is broken, undoing the screw should be straightforwrd.

 

I’m aware that you said earlier that you’d been able to remove the nut from the bolt holding the bracket to the step’s cassette (arrowed on image attached below) but still could not separate the bracket from the cassette. There MIGHT be adhesive between the bracket and the cassette, but I suspect that - now you’ve managed to get the step off the motorhome - it should be practicable to lever the bracket off the cassette to make the bracket easier to work on. There was a risk that removing the bracket would make tightening up the nut tricky when the bracket was refitted, but that shouldn’t be a problem now as you’ve obviously gained access to the cassette’s interior.

[Derek Uzzell]

The image below provides specification details of the 6 screws being discussed above.

 

They are said to be DIN 7981 TX25 5.5 x 32 mm and a pack of 10 in A2 stainless steel are advertised here for £1.80 (delivery cost included).

 

https://www.amazon.co.uk/Stainless-Tappers-Tapping-Screws-7981-10/dp/B07W8TCVHC

[Brian Kirby]

It may seem a bit defeatist, but have you explored getting a replacement bracket? The problem is almost certainly bi-metallic corrosion between the aly bracket and the (presumed) BZP steel self-tapper.

 

If the brackets as supplied are un-tapped then, when re-fitting it (whether you manage to retrieve the screw or just replace the bracket), it might be worth - even with s/s bolts - inserting and removing the s/t screw a couple of times, so that the threads are cleaned, and then fitting plain s/s bolts in lieu of self-tappers. If doing this, I think I'd go for plain steel s/t bolts to cut the thread (assuming you don't have a set of taps) as my experience of stainless bolts is that they aren't as strong as "regular" steel. The last thing you want is a stainless tapper that shears part way in!

 

Once the thread is good, then use a plain s/s bolt and place a split anti-vibration washer under its head, so the it can't unscrew itself in use.

[Derek Uzzell]

Replacing the bracket that has the now-headless screw stuck in it was something I considered as a last resort. However (and I did research this fairly carefully) the only way to obtain a new bracket seems to be to purchase Thule Part Number 1500603120 (for a 400mm-wide step) that is a ‘frame’ comprising the set of components shown on this Dutch advert

 

https://www.vorselaarsrecreatie.nl/index.php?item=thule-frame-slide-out-12v400-2016-ducato---1500603120&action=article&aid=6715&lang=nl

 

A 2019 Thule price-list quotes €72.90 (+ VAT) for the 1500603120 frame (with respectively €93.70 and €114.50 for Parts 1500603121 and 1500603122 for the larger 550mm and 700mm steps). I found one UK advert for the frame that quoted a £102.53 price.

 

http://campingequipmentshop.co.uk/thule-slide-out-step-ducato-2016-frame.html

 

(Rose Awnings probably could advise on bracket avalability.)

 

https://www.roseawnings.co.uk/product-category/thule-steps/

 

Even if the stubborn screw refuses to undo using the heat/wrench method I mentioned in my 15 November 2020 5:34 PM posting, Peter’s photo of the bracket with the screw in it suggests that it may still be removable by cutting the screw off flush with the bracket and then drilling down the screw’s centre. It also looks like there might be sufficient space within the bracket to get a hacksaw blade in and saw through the screw lengthwise.

 

I definitely agree that replacement screws should be greased and carefully inserted/removed on a ‘trial basis’ before refitting the step to the motorhome, though I don’t see any genuine gain in attempting to ‘rethread’ the brackets so that machine screws (bolts) could be used instead of self-tappers, particularly as the design of the bracket (clearly intended for self-tappers) does not lend itself to that type of conversion.

 

It’s got to be practicable to remove the stuck screw without damaging the bracket to the extent that a new same-size self-tapping screw could not be used. An A2/304 stainless-steel self-tapping screw should have a significantly higher tensile strength than that of a carbon steel equivalent, so the chances of snapping a stainless DIN 7981 TX25 5.5 x 32 mm screw would be minimal unless KIng Kong were tightening it up.

[BruceM]

peterjl - 2020-11-15 2:57 PM

 

Hi. UPDATE

 

I am thinking that I might try a blow torch next cos, whilst I haven’t disconnected I ca move it from vehicle.

 

Peter

 

Re blowtorching; heat the exposed end of the bolt until it glows, rapidly cool with water, repeat. Then clamp mole grips on to the bolt super tight and work the bolt gently back and form until it frees up. Looking at the picture it should unscrew easily. If the mole grips slip they’re not clamped tight enough.

[peterjl]

Hi

 

UPDATE ......SUCCESS

 

Thanks to all the advice on this forum the screw is now out,!!!,

 

I have ordered the stainless screw replacement Derek found on Amazon. Thank you Derek.

 

I will finish putting back tomorrow, using the 5 old screws, well greased, and then replace them when the ones from Amazon arrive Saturday.

 

Thank you all once again, that’s a big load off.

 

Peter

[Brian Kirby]

Derek Uzzell - 2020-11-16 8:48 AM..............................................................

Even if the stubborn screw refuses to undo using the heat/wrench method I mentioned in my 15 November 2020 5:34 PM posting, Peter’s photo of the bracket with the screw in it suggests that it may still be removable by cutting the screw off flush with the bracket and then drilling down the screw’s centre. It also looks like there might be sufficient space within the bracket to get a hacksaw blade in and saw through the screw lengthwise.

Drilling down the screw would be a job for a bench drill, I think, as it needs to be kept on line with more precision than I think I could manage to avoid accidentally straying into the bracket/threads in the process. But, there are a lot of small engineering firms around, some of whom maintain a "tea fund" for small jobs. :-) Maybe a possibility Peter could usefully explore? Might also be worth exploring drilling through the centre to leave the shell of the screw in situ, and then sawing through the remaining shell lengthways as you suggest and folding that in to disengage the threads with minimal damage?

 

I definitely agree that replacement screws should be greased and carefully inserted/removed on a ‘trial basis’ before refitting the step to the motorhome, though I don’t see any genuine gain in attempting to ‘rethread’ the brackets so that machine screws (bolts) could be used instead of self-tappers, particularly as the design of the bracket (clearly intended for self-tappers) does not lend itself to that type of conversion.

My fault. I wasn't clear. I wasn't thinking of re-threading the brackets after the existing screw had successfully been removed, but of threading a new bracket on the assumption one could be obtained at reasonable cost. (BTW, Hill View Awnings might also be worth asking about a bracket, as they seem to be able to get stuff via their wholesaler that isn't generally advertised. I've always found them very helpful.) But, I hadn't then realised that the screws were "regular" self tappers. I had assumed they'd be one or other kind of self tapping machine screw. Peter will have to take a little care to ensure the replacement s/t screws engage with the original threads in the bracket when starting them off.

 

It’s got to be practicable to remove the stuck screw without damaging the bracket to the extent that a new same-size self-tapping screw could not be used. An A2/304 stainless-steel self-tapping screw should have a significantly higher tensile strength than that of a carbon steel equivalent, so the chances of snapping a stainless DIN 7981 TX25 5.5 x 32 mm screw would be minimal unless KIng Kong were tightening it up.

True, but torx drives are very good in terms of not "camming" out as cross-head types do, which means it is much easier to apply high torques with no warning before they shear - often, seemingly, just below the head. These are longish screws, so the force required to drive them will rise as they feed in, albeit there is already a thread present. I'm assuming the bracket has been designed to ease a bit as the screw enters, as well as to clear the swarf as it cuts, so I'd anticipate the new screws will still need a bit of driving. However, I was primarily thinking of trying to drive a new s/s s/t screw into a new bracket. Perhaps I've been a bit unlucky with stainless steel screws, but I've been surprised that several sheared just below the heads as the resistance has risen. Albeit wood screws into hardwood - with an electric driver. But, if Peter can just get that seized screw out without mishap, he should be fine.