Suspension 2 point k-member brace vs. 4 point

[derek1993]

Picked up a 2 point MM k-member brace, thinking more on this i wonder if i should sell that and get the 4 pt as this is a convertible. Weekend cruiser so won't be doing anything crazy, but will add power to it later and knowing the convertibles can benefit from all the chassis stiffening available just has me thinking..
What say the experts of the board... (or even those who claim to be experts..)

Thanks.

 

[General karthief]

I've had/worked on many convertibles and the issue with them is cowel shake, there is literally no support for that area, a 2 point brace down on the k member will have little effect on this area, the verts actually already have a brace that ties the radiator support, k member and the front section of the frame rails so unless you're road racing that 2 point brace is nearly usless.
A 3 point or better yet, 4 point brace in the dog house would be better money spent.
JMO and based on personal observation, not scientific fact.

 

[Monkeybutt2000]

Hopefully you have subframe connectors. If not,get them. Then,get the MM strut brace and the 4 pt lower brace. I have this on my vert' along with FMS C springs and Koni oranges. Best handling Fox I've ever owned.

 

[derek1993]

Hopefully you have subframe connectors. If not,get them. Then,get the MM strut brace and the 4 pt lower brace. I have this on my vert' along with FMS C springs and Koni oranges. Best handling Fox I've ever owned.

I have full lengths going on, strut tower brace with FMS B springs and Bilstiens.. glad to hear it's worked well for you!

 

[eppd00]

I purchased my 83 GT convertible new. It is pretty much original, always garaged no rust etc. Of course I have been dealing with cowl shudder since day one. Years ago (20+) I installed the Global West sub frame connectors and their strut tower brace. I did not install their supplemental subframe equipment. Their instructions require the removal of the rear portion of the factory x brace concoction, which I still have minus the attaching screws and rivets. I had the car out last week after it had been stored for a few years and of course the cowl shudder is still there with the top down. Not so much with the top up. I was considering modifying the x brace mounting plate by cutting it ,screwing the side that attaches to the rocker panel and welding the other side of the plate to the sub frame connectors. I stumbled on this forum and was considering the Max. Motorsports 4pt K member brace. Based on your experiences, do you think this will resolve the problem, and do you think reattaching the rear portion of the factory x brace is a waste of time? Thanks

 

[General karthief]

Convertable cowel shake should have been mostly stopped with a strut tower brace if properly installed in the engine compartment.
how bout some pics?

 

[eppd00]

I made several pics. As you can see this is a 2 piece unit. The cross bar in front of the air cleaner is removable to get to the distributor

 

[7991LXnSHO]

That’s a good looking engine bay.

 

[ebone84]

I have a 91 convertible strut tower brace and the four-point lower brace makes a big difference tightens up my car incredibly.........

 

[eppd00]

I noticed the Max.Motorsport shock tower brace is a 4 point attachment rather than the 3 point style I have. (The only problem I would have with the Max.Motorsport tower brace is they want you to move the a/c line over the air cleaner snorkel on the passenger side rather than its original routing under the snorkel). I don't think that would be a good idea after 38 years and the original a/c lines still in place. I'll try the 4pt k member support and see what happens in a few weeks. Does anyone think reattaching the rear portion of the x member and welding the modified attaching bracket to the subframe feasible, or just a waste of time? I'll attach some phot os of the car

 

[eppd00]

I installed the 4 point MM k member brace and it appears to have tightened up the cowl shudder a good bit with the top up. It was a little too chilly to put the top down. I will try that the next time the weather warms up enough so the original top isn't damaged. I ask again from some of you fox convertible owners, do you think reattaching the rear portion of the x brace and welding the rocker panel bracket to the sub frame connector will improve anything or is it a waste of time? You have to remember this is an early GT convertible, #489 of 1001 built in 1983 (documented by the old 83 GT Convertible Registry). It does not have any of the full length rocker panel supports the later fox verts had. It only had the small support plates screwed and riveted in front of the rear wheels(which we successfully welded to the rear portion of the subframe connector) and the small plate behind the front wheel that attaches to the rear portion of the x frame.
Suggestions?
Thanks

 

[General karthief]

Look what they did to the newer fox verts, they did it for a reason. If you have subframe connectors already then those cast aluminium side braces I think would be unnecessary, I would but the X brace back underneath.
JMO

 

[eppd00]

Thanks for the response. What I will have to do to replace the rear portion of the x brace, is cut the rocker plate and weld it to the subframe connector. When we installed the sub frame connector, it covered the area of the subframe itself where the plate was riveted in. The rocker panel side can be screwed back into it's original location without any issue. I just wanted to confirm this was not going to be a waste of time. I appreciate the info. In my case old age is clouding my judgement with second guessing what I need to do.

 

[General karthief]

If it is a 'cut and weld' deal to install the rear portion of the X brace I would just install the front portion and call it done. I'm not convinced the rear part does much bracing. I have an aftermarket X brace on my hatch, beefier than that weeny vert part from the factory.

 

[Monkeybutt2000]

If it were me,I would go with the Stifflers "fit" system. I believe @a91what has this kit. It ties your subframes to the rockers,which is the strength of the car on a vert'. I will be doing this to mine in the coming months.

 

[a91what]

I do, it made a huge improvement on how the car handles and drives overall. Much more planted and stable.

 

[eppd00]

The front half of the factory x frame is in place per Global West sub frame instructions. As far as the Stifflers system, that sounds similar to the supplemental Global West system. This supplemental system is square tubing welded to the rocker with several round tubes welded between it and the subframe connectors. The reason we did not install the supp. kit was the fact it would be welded to the rocker...sheet metal. I'll take a look at the Stifflers system and come to a conclusion. General Karthief Tell me about the aftermarket x brace you have on your coup.
Thanks for the info.

 

[a91what]

The front half of the factory x frame is in place per Global West sub frame instructions. As far as the Stifflers system, that sounds similar to the supplemental Global West system. This supplemental system is square tubing welded to the rocker with several round tubes welded between it and the subframe connectors. The reason we did not install the supp. kit was the fact it would be welded to the rocker...sheet metal. I'll take a look at the Stifflers system and come to a conclusion. General Karthief Tell me about the aftermarket x brace you have on your coup.
Thanks for the info.

The factory subframes are also sheet metal, the pinch weld carries a significant load

 

[Mustang5L5]

Yup. On convertibles the entire structure connecting front and rear is through the rockers essentially.

I’m planning on installing the Stifflers X-bracing myself when I can get to it. I originally bought an MM 4-ppint brace until I bought an MM k-member. The aftermarket k-member does us a brace in the same location, which does suggest there is something to gain by supporting the K-member there. I’ve heard Jack Hidley claim this as well, mostly stiffness in side loading when cornering, but don’t quote me on that

 

[General karthief]

It ties the core support to the K member and the frame rails. It need powder coating and some new nuts and bolts. I got two of them.
don't recall where they came from