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MG MG Y Type - YT windscreen rubber

After 21 years of ownership, it's time to replace my YT's bottom seal on the windscreen. Dunno how old it is but the seal against the cowl is terrible and being caught in heavy rain means wet legs and instruments.
Can the brains trust tell me what's involved to replace the rubber seal between my folding windscreen and the scuttle cowling? Do I need to dismantle the windscreen frame to do this? What's the method that least disturbs the windscreen assembly ?
R Ades

Have you acquired the new seal yet?

Step one is to acquire the right seal of the right length and depth to the correct T profile. I believe I bought mine from NTG. It is deeper than a TD Screen seal from memory and longer too.

Step two, remove the complete screen in the frame from the car and completely remove all traces of the old seal from the bottom of the frame. Make sure the channel has no debris left behind. You may need to remove one of the side arms to do this so consider replacing the rubber the side arms sit on too. Dont forget to release the wire for the wiper motor from behind the dash switch and pull the wire out of the body. This is a good opportunity too to check the grommet around the wire to the body and again, replace as necessary.

Step three, use Lanolin to liberally spray the seal and the channel then gently feed the new seal into the channel applying more lanolin as required.

Step four, leave the seal in the screen frame on the bench for about a week to allow the rubber to naturally shrink back into place before mounting the screen frame back onto the car before doing the final mark ups for trimming the edges of the seal. When you trim the strip, make sure you allow for a large overlap per the picture attached to this reply. You can always cut more off: you cannot cut material back on once you have cut it off!!


Paul Barrow

Thanks Paul,

So the windscreen frame itself doesn't need to be dismantled? Removing the windscreen from the car is relatively easy. I have a few more wires to remove with the spotlamp, but there're small bullet connectors inside the cowl for this and the wiper motor. Side mirrors will need to be removed too. Wind-wings should be ok.

I haven't ordered the replacement rubber yet, but this pic shows why I need to. This rubber was a bit wavy when I bought the car and has only got worse.

If it just slides out as you've described, I'll be happy.

Regards,
Rob


R Ades

Should do Rob, if not then using a sharp box knife you can cut it along the channel edge. Be very careful cutting towards yourself so you dont slip.

How old is that strip? Looks like it has been subject to a fair degree of heat almost?
Paul Barrow

Thanks again Paul,

There was a little more dismantling than my description above. Wind wings had to come off (easy) and whole RHS frame-end eased off the glass corner at bottom RHS to expose the end of the channel. Not a big deal, but did mean disturbing the glass sealant in that corner. May require a drop of new sealant upon reassembly.

Worryingly, the wavy condition of the old rubber seal isn't due to heat. It's because the channel in the bottom of the windscreen is curved and the rubber extrusion is straight. The curve has the effect of compressing the outer/bottom edge of the extrusion, which it doesn't want to do, so a wave is created. When the old extrusion is pulled out and laid flat, the wave disappears.

I doubt that the NTG spare is extruded with a curve to match that of the bottom of the windscreen. How then does a new straight extrusion avoid the same wavy problem when bent into a compressed curve by the curve of the channel? Is there a trick to this?
R Ades

No trick. Where did you get that seal or was it on the car when you bought it?
Paul Barrow

...the old rubber was there when I bought the car 21+ years ago. It wasn't new then, so I don't know how old it is or where it came from.

I see the dimensions on on the NTG part are given as T-section 8mm x 2.5mm x 36.5mm deep, and this seal is stated as common for TD & YT. The old seal on my car measures as 9mm x 2.5mm x 45mm. Your note above says the YT seal is deeper and longer than the TD, so maybe this makes sense and NTG have rationalised their offering? Or, the 45mm old seal is too deep and that's why it doesn't like being curved?

It had a wave in the bottom edge as long as I've owned the car but has got worse over time. I try not to drive the car in heavy rain so haven't been too concerned. In long-distance touring mode we've sometimes added a strip of race tape to seal it to the cowl, useful in thunderstorm conditions. Other times we lay a towel on the top of the scuttle to collect water blowing in. In a recent club run, we were caught in very heavy rain with neither tape nor towel. Everything got wet, including us, the GPS, the rally instructions. Time to replace it. Hopefully the new rubber sits flat, despite being curved by the channel.

I've found a locally available T-section EPDM seal that's 8mm x 2.5mm x 38mm. It's not expensive so I'll pick up a length this week and see how it fits. If I'm not happy, I'll order the NTG version. Either way, car needs to be reassembled for a club Xmas run next weekend.
R Ades

Hi Robert

I will measure mine when I am back from work on Tuesday morning if that helps. Shoot me an email before you go to bed your time on Tuesday night and it should be on here and in your email for when you get up.

Paul
Paul Barrow

...so, I collected my new windscreen rubber and fully removed the old one.

First revelation was that the old rubber is 52mm deep. No wonder it didn't want to be curved back on itself on the bottom edge! That's a lot of extra material.

Second revelation is that the old T-section was over 10mm wide, much wider than the 8mm width of my replacement extrusion (same as the NTG part). This means the new T-section by itself is very loose in the channel and tends to pop out when bent over.

My solution is to run a longitudinally sliced 3mm PVC tube into the channel with the rubber extrusion. This packed out the space and can't easily be seen. Rubber extrusion now firmly held in the channel.

Looking at the first picture attached, the new 38mm deep rubber extrusion immediately formed a wave when forced to follow the curve of the windscreen bottom channel. Rather than leave this wave to set on the bench, I elected to fold the windscreen up into position so the shape of the cowl stretched out the wave. As can be seen in the second picture, the wave largely disappeared once this was done. I'll let the rubber memory set in this position for a while before I fold the windscreen again.

The shorter rubber depth 38mm vs 52mm can be seen in the paint condition on the scuttle cowl. Still, looks like a better seal. Next thunderstorm on the highway will be the test!





R Ades

This thread was discussed between 26/11/2025 and 03/12/2025

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