Ok so I recently picked up an 08 erc getting my first look at it tonight and I am already stump. I run a 16 1/2 seat.as I put my seat in the tunnel seemed to keep it from dropping in all the way. I took out the tunnel just to see and my seat Wil go down fine could space it up but I am thinking I will still run into the first problem.

So how are you guys mounting your seats in? Is there a trick?

Pictures? Not sure I completely understand what issue you're having.

If you want to spend some money and do it the absolute best way, go buy yourself a SCI seat mounting kit from kaedingperformance..... Expensive but super safe, and well worth every penny.

Another cheaper option is to have some delrin spacers milled up for the seat, a helpful trick is to do the right side 1/2 inch higher than the left to make the seat tilted- when you enter the corner it will even your seat out and reduce driver fatigue; canting your seat just a tad to the left is also very helpful.

I had two ERCs and had to forcefully jam my 15 in seat in them. They're pretty narrow cages compared to some of the other frames.

We have an 07 ERC and nothing bigger than a 14" seat would fit in it unless I really narrow up the chain guard.

You may need a different seat, seat manafactures have seats especially made for mini sprints that are squared off in the bottom. VS halo works well.

Actually I have done some mesuring. I can shave a 1/4 inch off my tunnel or chain guard and I can get a 16 down in the chassis. It was 15 3/4 measured for the inside of the frame rail to the chain guard