Im getting tired of dealing with these risers. I got some APC seats with sliders, but no risers. I thought I could make my own, but the way its looking its gonna be too tall for me (6"2). It looks like the best way is to cut the original studs the seats bolted to and drilling 4 holes (appx. 3/8") and actually bolting the seats through the raised parts of the floorpan. Meaning bolt head actually on the under side of the car. Ive heard somewhere on here that the floorpan isnt the strongest, I was just wondering if I could do this without risking a lot of structural integrity. Like I said, i tried modifying the stock risers, but its just too tall for me. With the seat sitting flat on the floorpan, its damn near perfect for me.

EDIT: On second thought, I could actually cut access holes in the raised part of the floorpan for the front 2 bolts, so actually Id only have to drill out 2 holes per seat through the floor. Does that change anything?

 

I think it's mostly a matter of opinion. Put some fender washers on both sides of the sheet metal, you should be fine.

 

I agree with fender washers however any post like this I want to clarify that I'm no expect and its just an opinion. Although if you get in an accident- even if the bolts ripped loose- you'd still be held in by a seatbelt. Drilling holes like that in the floor shouldn't cause structure problems either.

 

oh yea, not sure if you need to have your car safety inspected for insurance or anything, but it may red flag if you do it really tacky like...

 

well one down side is I have to find some 3/8" grade 8 cap screws (the ones with round alen head) cuz no other decent size bolt will fit inside the slider properly. I didnt wanna go below 3/8" bolts because the bolts are gonna need to be kinda long to go through the "hump" that the stock seat bolts up to. Didnt wanna a smaller bolt that could flex and crack under pressure. So if I can find some grade 8 cap screws, and are long enough, we'll be in business!

Oh, and some BIG A$$ washers!

 

Get the stainless steel ones, like every local hardware store will carry them.

 

allen cap screws are always L9 strength basically.

stainless would be nice, since it'll be below your car, but those are weaker (unless you get ARP ones...)

fender washers, or USS washers should be ok. (if you don't have room for a bolt head on the top, looks like no washer there eh?)

you don't have a "bolt supply" store in your city I take it? Maybe mcmaster.com if you can't find a local alternative...

 

3/8" cap screws are the only thing Ive found with a small enough head to fit inside the slider track. I got some damn big washers, and then some slightly big ones as well. Bolts I got for now are 4" long, which might be a little long but I can slways cut the extra off.

The only bolt store we got round here is Ace Hardware. They got a pretty good selection, but its not like specifically a nut and bolt warehouse or anything.

BTW: what is L9? Im not too familiar with bolt grades and strengths. All I know is grade 8 is about the best you can get.

 

cap screw means bolt. allen cap screw, or socket cap screw, means you use an allen key to tighten it.

L9 is like saying "grade 9". Grade 8 is the strongest "conventional" bolt. 150,000psi tensile. L9 (grade 9) is 180,000psi tensile. Almost everything made by ARP is L9. Allen capscrews are almost always L9 strength, by convention. (Unless stated otherwise). gr2 - low grade steel. gr5 - medium steel. gr8 - high grade steel. L9 - alloy steel.

Those 12 point head bolts with a washer built on it, (count-r-bor, are also grade 9 usually).

go to mcmaster.com and search through the bolts. then click on the "what does it mean" type of links to get more info. helpful info.

anyway, you've got a good handle on things. Gr5 in 3/8" should be plenty strong for what you're doing.

 

thanx sonix! Ive always been wondering what all that meant. Good to know what Im talking about now.

Just wanted to update. I cut off all the studs for the old seats on the floorpan, did my measurements and drilled 2 holes for the front. Worked great! Bolted just the front 2 down and its feels pretty damn strong, and everything is at the right height now. Ill get some pics up tomorrow when I get the passenger side in for future installers. Hell, I might even throw in a quick write up for those who are unsure.