I’ve been looking at lots of photos of slimline frames and they all have the raised brackets for the rear seat locating ‘pegs’. (The brackets are welded onto the inside of the rear shock upper mounts). My Domi 99 slimline frame is a 1960 frame but it doesn’t have those brackets. There’s also no evidence of the brackets ever having been there as I’ve stripped the frame and there’s no evidence of any welding. So did some frames (early ones?) have a different seat base that didn’t require the brackets to locate the rear of the seat? I’ve also seen some spring clips (they’re like ‘Terry clips’) on the RGM web site that say they are for the rear of a slimline seat and rubber bungs that fit into the seat pan, so it looks like there were at least two different seat bases for slimline frames. The seat that came with my bike has the two forward rubber bungs that push over the prongs on the frame near the back of the fuel tank and two long pegs that point downwards near the rear of the seat. I believe they are supposed to locate into the brackets that I don’t have on my frame. My seat pan has no rubber bungs either. My seat also has a Dzus fastener at the rear to fix it to the mudguard.
I’d appreciate any information that help me understand this odd situation (or prove that my frame is ‘odd’).
I once had a 1960 Domi 99 back in the mid-sixties. If I remember correctly, the frame had two prongs and rubbers under the saddle in the front. In the rear, I'm certain it was two spring clips. Reason I'm shure is that the seat came loose when I did a 20 metre jump on a hump bridge.
You could have a DL frame that has been part converted . Should have a DL seat to go with it (terry clips etc) ,Easier to get the frame altered to take your seat. DL seats are rare. Its possible that there were some std twins made for the 60 season with the clip down seat ,but I don't remember seeing one. Mot inspectors don't like them as seats are supposed to be securely fixed.I strap mine down. My first 88DL was badly damaged and I rebuilt it just as your bike is. Its now been "converted" into a genuine 88SS . Whatever that means!
Thanks Mikael and Robert. It doesn’t surprise me that my 99 is a bit of a mongrel - it belonged to a farmer who almost rode it into the ground before chucking it into a barn for 35+ years.