Welcome back folks,
In this post, we look at making one of the most crucial parts to the build, a comfy place for your arse to go!
I am of course talking about the seat. Due to all the unique modifications (butchery) that have taken place, I need to create a bespoke seat pan to fit the new profile of the frame.
This seat pan is an integral part of the build because if you get this wrong, it can end up with your bike looking a little weird. And nobody wants a bike that people go “yeah that bike looks really cool from far away, but have you seen the seat? it looks like hammered shit up close”…Not wanting to be the subject of an expectation vs reality meme (see below) I took a little extra time planning this out.
Now bearing in mind, this is the base and there will be padding and then material on top, which will change the thickness and overall profile, there is a little guesswork to be had in deciding how the seat pan mates up with the frame.
From the side on you want to make sure that that the pan is long enough and mates up nicely to the profile on the tank. From the top, you want to make sure it sits evenly on the frame.
I debated long and hard about this (with myself… in the garage…like some kind of crazed lunatic). I quite like being able to see a bit of the frame from the top down. I have seen other bikes where this isn’t the case, but I think for this build it will suit the style/really hope it suits the style. This decision comes back into play later on when trimming the seat pan.
Ok, onto the good bit, making a mess and getting itchy…sounds just like.. (I’ll leave this one). I am talking about building the bloody seat pan, get your minds out the gutter
There are several steps to building a seat pan. depending on your chosen material, these can vary. They can be built of thin steel or fibreglass. I chose the fibreglass method as my uncle kindly donated some from a leftover project.
The first steps are to get rid of the gaps in the frame to allow you to lay up the fibreglass. To do this I used some Duck tape (which was heavily discounted at B&Q….and no it’s not from my personal collection!). I wrapped tightly all around the frame. It is important that you keep it very taught, this ultimately provides the base shape so you don’t want it sagging through the frame.
Next, we want to place something between the fibreglass and ducktape. this is to allow easy removal of the mould. Robbing the kitchen of the cling film, I followed a similar process to the duck tape…although iI instantly regretted trying this outside…the clingfilm turned into a god damn kite! Once you have wrestled this on, you can polish this with some car polish. My rusty Subaru stared at me in disbelief as I used my nice polish on a piece of clingfilm rather than him. Maybe I’ll treat him to a drive-through car wash…MAYBE.
With the seat pan ready to go, I next measured out how much glass fibre I would need to make the seat pan. Always cut more than you need to and trim to size afterwards. I cut out enough for 3 layers.
It’s a good idea to do this before you start because once you mix the resin the ticking clock starts. It also tends to get everywhere, so it’s nice to do this once. On that note, this stuff is itchy….you will more than likely look like Baloo here if you get it on your skin, so be careful:
The next step is to make up the resin and soak the fibres. This bit is fun, You have a resin and a catalyst. Get an old jug, do NOT borrow the kitchen jug (note: buy a new jug for the kitchen), and mix out more than you think you will need. Stir vigorously then you are good to go.
The next step is to layer up the seat with fibre and resin. See below sped up video.
This is the method I used:
- lay matting over the entire base
- Pour resin liberally
- stab and stroke with the brush
- lay matting
- Get so covered in fibres your gloves become unusable
- Pour resin liberally
- repeat until you have 3 layers well saturated
- Clean jug and pretend it never left the house
A key thing is to make sure that there are no bubbles, so spend a bit of time making sure you can’t see any. You can also buy little roller tools to help get rid of these bubbles.
You should have something that looks like the below once done:
The next step…have a cuppa…or several because this takes a good few hours to cure, I left this overnight to set properly.
You then need to trim this to size. As mentioned earlier, it’s much easier to have more and to cut away. This part is probably the most fiddly of this little project, as there are lots of measuring, trimming, swearing and measuring again. See the gallery below for the process:
The MVP’s for this job were the Dremel with a cutting attachment and the little Makita hand sander. The sander was especially good for when you got to the final adjustments and a rogue Dremel cut would ruin the whole thing.
You then end up with a seat base that looks like the below:
So this follows the centre of the loop fairly well, and I think once you get it covered it would almost look ace…see below
There are a few key lessons learned from this:
- Make sure it mates up properly with the tank – I removed my tank and didn’t make it long enough, by probably 1/2″ (DOH). Is what I have already suitable…probably, but let’s go back to my earlier scenario of the bike looking like shit because the seat just isn’t quite right…
- Make it larger than you need – I have made a poor attempt at a seat base on my XS750 build, but I was short on fibreglass so didn’t make it wrap over the frame. This build I did and it made trimming much easier.
- Buy lots of fibreglass from a supplier rather than those piddly kits from Halfords, it costs about the same and you get way more
So I was going to talk you through how this would be mounted to the bike, but I Have a few ideas which I will cover in a later blog post. For now, I have enjoyed building this so much I have decided to do it again, this time mating up properly to the tank….ffs…
I have some big news to share next time,