Advice on header collector ball flange bolts ...

[LateApex]

I am using the FFR SS headers with the ball flange. The bolts and lock nuts are what also came with my kit. This collector to side pipe fastening system is ALWAYS loosening, not because the lock nut is loosening; rather because either the bolts are stretching or the ball flange itself is changing shape with the thermal cycling of the exhaust system with each run.

I have tightened those three bolts on each side maybe 6 times since I started driving the Coupe in earnest this Spring: More often than I check my fluids :-) Today, I pop open the bonnet, and I can spin one bolt by hand on each side pipe.

I know they are loosening when I start getting a "Pop" or backfire through the pipes on deceleration. A little residual fuel vapor in the exhaust when I drop the throttle mixed with nice fresh O2 leaking through the ball flange, ignites quite well with the heat of the sidepipes, and immediately tells me the damn bolts are loose again.

So, stainless steel is not a great fastener material, as it is weaker than steel. I believe the bolts are stretching. Stainless is a good material for corrosion resistance, but maybe not appropriate for this application. Thoughts?

Thanx in advance ...

[Jeff Kleiner]

You are correct. Use hard bolts and deep brass (AKA "Coupling") nuts.

https://www.poolsupplyunlimited.com/Products/Product2/106588_0_2017117112718.jpg

Jeff

[LateApex]

Thank you Jeff! What do you mean by "hard bolts"? Grade X Zinc plate?

[Jeff Kleiner]

Thank you Jeff! What do you mean by "hard bolts"? Grade X Zinc plate?

Grade 8

Jeff

[LateApex]

As forecast, again I am dealing with loose ball flange bolts/nuts. I fire up and I hear a rattle. As the engine comes up to temp, the rattle dissipates. I get back to my garage, and the ball flange is loose, again. It does not matter how much torque is applied to those fasteners

I am quite certain that the bolt / nut combo is not unwinding; rather the ball flange is morphing with every heat cycle. Are others having this issue? Is there a cure (aside from spending ~$3K on Quiet Pipes or building your own exhaust system?) The ball flange approach is lame and is no more than a patch of a design that reflects poor "Geometric Design and Tolerance" consideration in the frame / engine mount / body cutouts and manufacturing variance. This should not be on the price list! DO NOT BUY THE FFR EXHAUST!!

Grrr!

[DW66]

I used grade 8 bolts and double nutted them. Haven’t moved in 7500 miles?

Dave

[LateApex]

I used grade 8 bolts and double nutted them. Haven’t moved in 7500 miles?

Dave

I have grade 8 bolts and have have tried both lock nuts and brass header nuts (as suggested in a previous post) I know the fasteners are not loosening. There is something going on with either the ball flange shape or the "stainless" metallurgy. From your photo, You may have a different exhaust vendor (you have built a roadster ? - mine is the Coupe). Next time my side pipes are off, I will figure out what grade SS is in play in the parts I received from FFR.

Thanks Dave for your reply. Best ...