Connecting 4" clay onto 110mm plastic

[Matt182]

Got a bit of a weird problem, I'm trying to connect onto an underground clay drainage pipe (OD 122mm) that takes the rain water from the guttering's to a soak away with 110mm plastic pipe.

I purchased this adaptor Floplast underground flexible adaptor 120-136mm however when I tighten it up it bulges inside creating a lip/gap.

Was wondering if anyone has come across this before or is it just how they are? Wasn't sure if I needed something like a Flexseal AC5144 Adaptor instead for a tighter fit?

Thanks,

Matt

 

[Nige F]

Won't matter much on rainwater pipe

 

[CBW]

Perhaps too toght