A TAG Heuer Formula 1 WAH111C Grande Date Alarm arrived at Ross Watch Repairs after moisture had entered the watch. The reason was not immediately obvious from the outside: the winding and setting stem was too long, preventing the screw-down crown from closing fully against the case.
Once the fault was identified, we replaced the internal mechanism with a brand-new Swiss Ronda 4120.B quartz alarm movement, adjusted the stem to the correct length, and polished the stainless-steel bracelet. Crucially, we then tested the watch’s water resistance. The workshop test showed passing results at the displayed –0.7/+5 bar test settings.
Repair at a glance
Watch TAG Heuer Formula 1 WAH111C Grande Date Alarm
Problem Moisture inside the case
Cause An overlong stem stopped the screw-down crown closing
Repair New Swiss Ronda 4120.B movement, stem corrected, bracelet polished
Result ✓ Passed –0.7/+5 bar pressure test
01 · The fault
How an Overlong Stem Allowed Water Into the TAG Heuer
The TAG Heuer Formula 1 WAH111C uses a screw-down crown to help protect its movement. On this example, the stem was too long, stopping the crown from screwing fully down to its intended seated position. That left the crown’s sealing arrangement unable to close as designed, allowing moisture to get inside the case.
Good to know A crown that appears pushed in is not necessarily properly secured. The stem length and crown fit must be correct, particularly on a watch that may be exposed to moisture.
TAG Heuer’s official water-resistance advice stresses that crown closure and ageing seals affect a watch’s ability to resist water.
02 · The new movement
Replacing the Swiss Ronda 4120.B Alarm Movement
This Formula 1 is fitted with the Ronda 4120.B, a Swiss quartz calibre with an alarm, small seconds and a large two-disc date display. Unlike a basic three-hand quartz movement, the alarm mechanism and the additional indications make it a more specialised replacement.
Ronda’s 4120.B technical information documents the movement’s alarm, big-date and small-seconds functions.
Because this watch had suffered moisture ingress, we fitted a brand-new replacement mechanism rather than retaining the affected internal movement. The original dial, hands and case components were carefully handled during disassembly and refitting.
03 · Dial & hands
Disassembling the TAG Heuer Dial and Hands
The repair required removing the dial and hands to access and change the movement. The photographs show the distinctive black Formula 1 dial, red alarm hands, luminous hour and minute hands, and the large date display at six o’clock.
After the movement was replaced, the watchmaker refitted the dial and hands and checked the watch’s indications during reassembly.
04 · Crown & stem
Correcting the Stem Length and Crown Fit
Replacing the movement alone would not have addressed the cause of the water damage. We also cut and adjusted a stem to the appropriate length so that the crown could screw down properly against the case.
The stem must be long enough for reliable winding and time-setting functions but short enough to allow the crown to seat fully. This is a critical distinction when repairing a moisture-damaged watch with a screw-down crown.
05 · Pressure test
TAG Heuer WAH111C Water-Resistance Test: Passed
After reassembly and the crown-stem correction, we carried out a water-resistance check using our Watchmaker M+ pressure-testing equipment.
The test display recorded a pass at –0.7 bar and +5 bar, with green checks for the test cycle. This was an important final check because the original fault had involved the crown failing to close correctly.
Important The caseback of this model is marked 200 m, but the photograph documents the specific –0.7/+5 bar pressure test performed here. A pass at these settings should not be described as a full 200 m or 20 bar certification. Appropriate future water exposure should be judged against the actual testing performed and the condition of the watch and its seals.
06 · The finished watch
Full Bracelet Polishing and the Finished Watch
Alongside the mechanical and sealing work, we carried out a full polish of the stainless-steel bracelet to reduce surface scratches and improve its appearance.
The completed watch retained its distinctive Formula 1 alarm dial and stainless-steel bracelet, with a replacement Ronda movement installed, the stem corrected and a documented passing water-resistance test.
Work carried out
- Fault traced An overlong winding stem was stopping the screw-down crown from closing.
- New movement fitted A brand-new Swiss Ronda 4120.B quartz alarm movement replaced the affected mechanism.
- Stem corrected The stem was cut and adjusted so the crown screws down fully against the case.
- Pressure tested Passed at –0.7 bar and +5 bar on our Watchmaker M+ tester.
- Bracelet polished The stainless-steel bracelet received a full polish.
Advice
Can a TAG Heuer Crown That Will Not Screw Down Be Repaired?
Often, yes. The issue might involve an incorrectly sized stem, worn crown threads, a damaged tube, deteriorated seals or other components. The correct repair depends on assessing the actual crown and case, not simply forcing the crown closed.
If your TAG Heuer crown will not screw down fully, avoid wearing the watch in water until it has been professionally inspected. You can read more about our TAG Heuer watch repairs, full watch servicing and individual watch part repairs.
Free assessment
Crown won’t screw down, or moisture under the glass?
Bring your watch to The Shard or Canary Wharf, or send it to us by post. We assess watches free of charge and confirm the cost before any work begins.
Visit or post
TAG Heuer Repairs in London and Across the UK
Ross Watch Repairs offers free assessments for TAG Heuer watches, including crown and stem problems, movement faults, moisture ingress and water-resistance testing.
The Shard / London Bridge
Ross Watch Repairs, 306 The Shard Retail Arcade, London Bridge St, London SE1 9BZ.
Canary Wharf
Ross Watch Repairs, Unit 4B, Cabot Place Shopping Centre, Canary Wharf, London E14 4QT.
Postal repairs You can also use our UK postal watch repair service. Send your watch to our Canary Wharf branch by Royal Mail Special Delivery and include your name, telephone number, email address, return address and a note describing the problem. We assess watches free of charge. Payment is taken on completion. A £15 postage and packaging charge applies to postal repairs under £50, assessment returns and warranty returns.
FAQs
Frequently Asked Questions
Why would a TAG Heuer crown not screw down?
Possible reasons include an overlong stem, damaged crown or tube threads, or other fitting issues. In this repair, the stem was too long and prevented the crown from seating correctly.
What movement is used in the TAG Heuer WAH111C?
This Formula 1 Grande Date Alarm uses the Swiss Ronda 4120.B quartz movement, which provides an alarm, small seconds and a big date indication.
Does a 5 bar pressure-test pass mean the watch is waterproof to 200 metres?
No. A test passing at the displayed –0.7/+5 bar settings confirms the result of that specific pressure-test cycle; it does not, by itself, certify performance at 20 bar or 200 metres.
Do you repair TAG Heuer watches by post?
Yes. Customers across the UK can send watches to our Canary Wharf workshop for a free assessment using Royal Mail Special Delivery.
