Haven't done SFC's yet - need to, and will soon. Wanted to know the verdict on the theory of bolt-ons and the elongating bolt holes after use - so anyone that installed the bolt-ons years ago, still has them, and has looked lately - what's the verdict on elongating holes after use?

 

hi , i have bolt on sfcs....i always planned on having them tack welded here and there but never did...i have these sfcs for at least 5 years...i sometimes look at the bolt holes and try to tighten the bolts a little ,,but they haven't moved yet..i think it's good to bolt them on and then have them welded in certain areas,,but if your like me who doesn't drive his car much ..there is no problem..with the SFCs & strut tower brace and wonder bar,, my car hanldes really well..It's funny ,,i was looking at your car's specs...we have a few things in common..the 350 ..edelbrock carb etc...good luck..

 

bolted on SFC will always move more than welded ones. The holes will elongate slightly over time and you will loose some of the effectiveness of the SFC.

Bolt on ones are good however, because they usually have a larger mounting area, and you can install them yourself, then drive the car to the shop to have them welded in.

Its kinda like getting new tires and not puting air in them, sure you have new tires, but they wont be very useful.

 

ya , your right...they were a breeze to bolt on ...and i always planned on having them welded on a few spots to make sure they don't move....but so far so good and like i said i don't drive too much...one day i will get them welded..

 

even with bolt-ons you should weld them down the middle against the pinch weld in the car to get the full effect of sfcs. So if you are going to weld anyways, why not just get weld ins?

 

I think the biggest benefit to bolt-ons, is what has been said already.....

You can bolt them on at home & drive to a shop to have them welded. Saves you the $$ of their labor for the install of even holding up weld-ons to be welded in place.

And it might have a lot to do with HOW you drive the car. Simple daily driver, to & from work? Bolt-ons may be perfectly fine & never elongate the bolt holes.

But for a track car or very spirited street driver, I'd go with welding them on.

All that being said & thinking about it....I might just sell my KBDDs, get some bolt-ons & weld them on when I can.....

 

my car isn't a daily driver ,,i use it on the weekends 1-2 times a month in summertime...in 5 years my sfc 's haven't moved or enlarged any holes...but if i would drive it more i would of got the weld on type sfcs....i still plan on having them tack welded to the floor and other areas,,just haven't got around to it...the benefit of bolt on sfcs are that you can bolt them on at home ...while i installed mine ...i removed and changed the carpet and seats...i completely painted the floor with flat tremclad paint from the firewall -pedals to the rear seats...then bolted the sfcs on and used lots of large washers to make sure the holes wouldn't enlarge too much..it was a winter project and i took my time...this winter i just converted my rear drum brakes to disc brakes with 1989-92 pbr brakes...last winter it was my auburn posi ...i try to have something to do on the car each winter since the winters here are long and cold...later.

 

Movement is going to be really hard to see unless you closely inspect all the parts. If you did not take the bolts out and inspect the bolts and the holes, no way to know if things are elongated or not. Even the bolt not having come loose isnt going to tell you whats going on with the connection. TDS sells nylock nuts with their Alston SFC's so chances are they will be just as tight as they were originally since the only way a nylock really would allow there to be less torque is if the distance between the flanges on the SFC decreased.

I have seen inadequately bolted connections loaded to the point of failure of the members it attached to and visually without disassembling the bolted connection it looked ok. Upon inspection the shoulder portion of the bolt was damaged, along with the threaded portion (that was easiest to see) and the holes clearly mic'd as being oblong. The most suspect place to check first is where the threads on the bolt touch one of the flanges on the SFC and the frame. If the threads are smashed down, pretty clear its moving. A bolted connection requires a certain number of properly torqued bolts to function as a solid connection. The Alstons, it appears, use two bolts on each flange. Thats marginal, at best. Given that its a u-flange attached to a thin box steel 'frame' I would be really skeptical that any adequate torque can be applied without things bending. I've bent frames on these cars from a lot less than a torqued bolt.

I'm curious what sort of torque value you were able to obtain as I've never tried it or used bolt on SFC's on these cars. Have a number to post up?

 

these SFCs i got run along the rockers front to back...at the front they start from right under the firewall (kick panel) and go all along the rockers to the back bolting on the bars...each SFC has 8 bolts total...7 huge nylock bolts and one bolt which is on the car already for the rear bar that is hooked to the diff....made from solid square tubing steel...like i said, even if they don't enlarge the holes,,i will get them tack welded all along the floor for extra strenght,,,i paid $180 with shipping .

 

In reality if you wanted a proper bolt in job you should drill the hole bigger and weld in a cross piece of pipe for the bolt holes. Given the forces they can be subject too. That would be smart in the long run.

Still gotta weld but they can bolt in and never need to worry about the holes.

 

"Now THAT"S usin' yer dipstick, Jimmy!"

 

What bolt on SFC's are you guys running?