jranaudo

Looking to mount my lap/sub belts to the frame.

Has anyone done this? I would prefer not to install a roll cage as this is just an HPDE 6x per year car.

If you have done it can you send pics? What happens with sub belt mounting since floor of C5 is balsa wood? Any shops in Northeast/NY Metro area (willing to drive)?

Thanks!

Quickshift_C5

You'll have to secure a metal brace underneath and thread the eye bolt into that or use an SFI approved backing plate to distribute the load, then thread the eye bolt in there. You'll still need to attach the backing plate to a secure brace, as I wouldn't trust it with sheet metal/wood floor. If you just simply put it through the floor, it'll likely rip out in an accident. A few of the seat brackets available have provisions for sub belt mounts.

Lap belts seem like a mess. This is where I've been struggling. It makes the most sense to use the factory frame location on the door sides where the OEM lower belt tensioner is mounted. It's at a great angle. Secure, pulls at the right angle, puts the belt at the right length. However, I've been struggling with the darn bolt size. I thought it was 1/2-13 course, but I bought a bolt to test and it doesn't even begin to thread in. However, the 7/16-20 fine eye bolt I have from my harnesses is too small. I've been looking for confirmation on this bolt size. But...you SHOULD be able to thread an eye bolt in there with a lock washer or a couple wavy washers and threadlocker and clip in.

The trans tunnel side is tough. I simply don't have room to mount an eye bolt ANYWHERE...so it'll depend on what seats you go with. I secured that side to the seat bracket, but I'm not happy with it at all. If you can get the clearance, going through the floor makes the most sense. Behind the seat makes the belt pull on the back of the seat, side of the seat, hardware, etc. On the side of the bracket makes the belt go across hardware and pull at a bad angle through the seat opening, depending on how the seat is mounted to the bracket.

jranaudo

what a pain in the ***. SOMEBODY out there must have accomplished this.

aaarrggghhh!

fatbillybob

Less than Ideal solution but this is what I did when I 1st tracked my car to see if I wanted to race a C5Z.

Assumed seat bolts are strong enough because driver and seat are retained by them. 50G crash is what is considered survivable in a streetcar today. Make angle iron drilled 6 holes. 2 captured under rear retaining seatbolts. 2 outboard holes for lap belts at right angle for me. 2 inboard holes for sub straps run as parachute style 6pt harness. harness bar for shoulders. I think most dual use cars are very questionable for safety. Most data comes from stock oem safety gear and full racecar cage setups. Once I was done with this setup I went to a full race cage etc... Think seriously about dual use set-ups. It is much harder than you think and in my mind impossible.

jranaudo

I know there are people who say I am being obsessive about it.

I know HPDE is relatively safe but I am just being uber cautious.

Honestly I could keep it stock but the stock seats are HORRIBLE. I spend most of my driving effort on holding my *** in place.

Quickshift_C5

jranaudo

Pretty sure the racers mount it to the cage they install. I would prefer to keep my C5 cageless.

Maybe I'll just get a friggin slow & fun miata. FML

Quickshift_C5

If they have a full cage with side bars, definitely. I'd sure like to avoid attaching mine to the seat bracket, as it rubs against the seat hardware when pulled tight.

Every other belt, there is a solution if you can find an eye bolt that will thread into the frame on the door sides. Seat brackets will give you proper sub mounts. Then you just need to find a harness bar that is at the right angle for your seats/passengers. My brey krause is too high for my passenger seat.

mellojoe

I know this is a week or so old, but I wanted to chime in. I was under the impression that you DON'T want to go through the floor into the frame by itself. In an accident the body and frame can move separately which can cause sheer and basically cut the seatbelt loose of its mounting. This is why you need a full backing plate under the body. It secures the belt to the body, but strong enough by spreading the load out. I'm pretty sure this is what QUICKSHIFT_C5 was referencing. Adding lapbelts or harnesses aren't as simple as just running an eye-bolt into a frame. It isn't quite the same as, say, mounting something securely in a house frame. Because of the way vehicles respond in accidents, you have to take into consideration all the moving pieces, and how the frame moves separate from the body panels, and what parts are designed to crumple vs those that are part of the passenger rigid cage.

Quickshift_C5

mellojoe

Gotcha. I didn't realize he was talking about using the same OEM mounting points. I was concerned he was going to drill through the floor in a different location and hit the frame. My experience is not so much with the Corvette but with other off-road style projects where you have a metal body on a steel frame, usually. And in those cases, yes, you do have a plate between the body and frame.

_BlueZ06_

I have my belts mounted through the seat rails and eyebolts. For the lap belts, I drilled a new hole and have added material to the backside for reinforcement. I used the eyebolts and belt clips to push the belts further out to keep from rubbing against anything. The sub belts are mounted to the seat rail further up front with eyebolts and a backing plate. I drilled the hole to a close tolerance so there isn't any play.

Quickshift_C5

Which seats do you have? My seats just don't give me the clearance for an eye bolt on the trans tunnel side. Did you do something particular on that side to get the eye bolt to fit?

crimlwC6

I had a rod bolted or welded to the race seat for sub belts and I've also used the strap mentioned in above post. The metal strap under the car is, imo, necessary when you are running a race seat to spread load. Bolt with eye hook for the trans tunnel. Momo seat and aluminum seat have been in car.

KEZ06

I didnt mount it to the frame, but i did use the vetteworks lap bars for my 6-pt harness. They are bolted down at the rear seat bolts. I did do an rsd bolt in rollbar and the shoulder harness attached to it.

jranaudo

Just wanted to clarify.

The rob you bolted or welded to the race seat. You mean you bolted it to the seat mounts correct? vs the strap which is mounted to the frame to spread the load. Is my assumption correct?

I get the bolt with eye hook for trans tunnel but where did you mount the left hand side to?

Sorry if I seem confused. I am lol

crimlwC6

Your confusion makes sense; I wasn't clear. Rod bolt was welded to the seat. I also have used the strap method under the bar between the factory seat bolts for sub belt mounting and the spread the load for the race seat. I have run a few different setups in the car.

Quickshift_C5

I'm still not sure I follow. You're running another bar underneath the car between the two straps/bars that the seat studs are mounted to, to spread the load of the sub belts. Right? Like this? So, you're basically removing the load of another set of belts off the seat rails, so the only ones attached are the lap belts.



I've been wanting to do this with ALL the belts, but I can't find a way to get an eye bolt anywhere on the trans tunnel side...neither attached to the seat bracket or on the floor. There simply isn't enough room, unless I use different brackets that allow me to move the seat side to side.

crimlwC6

Straps run the other way on my car and they, to my recollection, run to the factory bolt locations both at the front and rear. I have run sub belts that just run to the rod that is welded to the seat. I have also ran the sub belts to the factory frame bolt mount holes with the strap ran under the car.
I just re-installed an old seat.The right side rear belt attaches the trans tunnel. Mine uses an eyehole bolted through the trans tunnel. I don't recall if this was done with the torque tube moved but I think it was done with the TT in the car. I know it is frustrating to not get a 100 percent answer on the forum but a race shop will have the answer. More than 1 way to skin a cat and guys have been tracking these cars for 20 years.

Quickshift_C5

Yeah, it's quite the puzzle. All C5's have the factory "straps" run the same way, as in the photo. So I'm not understanding what you're talking about. When you say "strap", you're referring to the crossbar spanning the width of the floorpan that the seat studs are mounted to, right? Unless you're talking about the bars you added for the sub belts, and you ran them parallel to the existing bars, opposite of my photo.

No idea on the eye bolt in the trans tunnel, can't shoehorn something in that simply doesn't fit. What I've been attempting to do is figure out how people got the clearance between the seat brackets and trans tunnel to even get an eye bolt in there. I'll have to go with completely different brackets to do that...I wish I could.

There are no race shops here in the middle of Iowa, but if I want to change my setup, I may have to find something.