I run both. Mac and SPOHN. I like both. Inners are beefier and tie the front subframe directly in a straight line to the rear subframe. The outer style has a tube run along the rocker that is stitch welded along the rocker (I've jacked the car from these and they work really well) and then there's a tube that connects the front part of the outer tube to the front subframe, and the rear end of the rocker tube has a small tube that tie into the rear LCA mount part of the frame (not the beefy rear subframe). So, the inners and outers tie in different parts of the subframe/body/rocker..

Also, yeh I've been looking for those KB pieces for a couple years now.. No luck

 

Thanks for your input. Yeah I think I have a pretty good idea now of the inner and outer design, just not sure which one is better or for what application.. Anyways prolly gonna get both as said
Which ones are those KB pieces?

Does anyone know if you can stitch weld the UMI boxed ones to the rocker rails or are they too far away to do that? Summit has a 2 weeks backorder on the GlobalWest :/ I kinda have to get the SFCs from Summit because of shipping options..

 

The KB bolts into the front subframe near the front of it (sort of like under where the tranny and engine meet) and ties in both sides of the frame under there.

 

I just welded in the Spohn connectors for my 91 convertible. Not many options for a vert. I screwed up and ordered the powdered coated ones. I didn't realize that I would have to sand it off to weld it in. I'll let you all know if they do whet they are advertised to.

 

I bought my "alstons" back when Saleen sold them w/ Areo Camaro labeling.Been on the car 20yrs now.Bolted on first, then welded.

Nice thing about these they fit coupes/verts & single/dual cat exh.

 

FueledSoul, is there any chance you would be willing to make and sell me a set of those connectors?

 

After reading this entire thread and searching every thread I could find on every subframe connector still offered I have but one solid piece of info. Nobody agrees as to which is best. S&W looks like a better kit than most, but the cross bar hangs really low. Looks like going with the perimeter style along with the alstons is the best bet.

Is there anyone running a Mufflex 4" system with ANY of these connectors?

 

Its very easy.

Alstons take a very pricy hydro from machine to build and shape the tube.

All the rest you can make at home with square stock and a welder.

 

I run the UMI perimeter ones with my 4" Mufflex. Also had purchased and trial fit the TDS ones to add but used them on my firebird instead. Now I just purchased a set of MAC's inner ones to install. They all clear just fine

 

I have a set from UMI

 

you dont say..

 

I tried to mount the MAC inner ones on my camaro today. Camaro already has UMI perimeter ones on it and found they wont install if you run a spohn t56 crossmember. already ordered a Hawks crossmember for the Firebird so will check when it arrives. Might have to buy a second one

 

Any difference with the subframe connectors versus without?

 

I noticed more when I put the perimeter ones on my camaro than I did when I put the inner ones on my firebird. But the camaro had bad door hinged and was overall in a loose and rattle prone compared to my firebird which was tight and doors closed perfect. In short, yes they make I big difference. But you can only run perimeter if you have any aftermarket crossmember due to a trans swap. Inner won't clear hawks or spohn T56 or 4L60E. I tried them both on both cars

 

I have MAC inners and SPOHN outers but was hoping one day to do an LS1 swap.. That kinda sucks, I guess I would have to cut the inners out or something.. Wouldn't a 4L60E fit in the 700R4 stock crossmember? Doesn't the 4L60E have the same external dimensions as the 700R4?

 

The LS 4L60E is set back just like my LT1 T56 in my camaro. Only thing I notice is the bellhousing is different on the ls. I have to cut out mine on the firebird to use the hawk crossmember. Actually going to try to modify it to still work. Just bought a set of BMR perimeter for the Bird cause my goal was to run both on both cars.

 

I went back and double checked my facts. Yes the ls 4l60e had a different mount location than the 700r4 & lt1 4l60e but the over all length is the same

 

BMR perimeter w/TDS aka Alston inner will work with minimal modifications using a hawks crossmember. UMI perimeter will also work it's the Mac inner ones that seen se be the problem.

 

I too have a 83 Z28. (LG4) a local club member basically gave me a pair of the Mac's (for a beer).

Do they fit the 82-85 cars?
Sorta.

The Driver side is a perfect fit (just protect the gas and brake lines prior to welding). The issue on the passenger side is not the transmission mount/crossmenber, or what have you. The issue on the older cars is the "massive" pellet style catalytic converter used in many of these cars. If you plan to keep the stock exhaust and the stock catalytic converter then there is not enough clearance. but if you swap in new OE cats or smaller aftermarket cats then it will fit your 83 just as nice as an 86-92.

 

I figured i would upload my home-made sub-frame connectors, iv had them on the car for about a year now..passenger side is not complete yet though..All the driver side needs is to have a plate that boxes in the rear LCA mounting location...i used Square tubing and an arc welder.. 1"x1"x5/16" square tubing.

 

Not to be an as.s, but I would take it to a shop or anyone with a mig welder and lay a hot bead over the welds already there, maybe grind them down a little. Kudos for DIY Just trying to provide some advise, not meant as an a hole comment

 

The welds look worse than they are, i used 6013 3/32 rod for pentration which does go all the way through because where each tube meets i did a V notch and did multiple weld then grinded down then did a one pass over with the 7013 1/8" and only grinded down where it meets the floor pan no need in making the welds look 100% perfect on top of the metal,for as noone knows i have them until i tell them..although i will be taking it to a muffler shop to have them welded into place on the pinch area and on the from subframe.

 

see , that sinks their ship . as far as im concerned. im looking for SFCs that just plain fit. but i guess its same as with headers. "some hacking required" and , really ? F that !!

 

Does anyone have the S&W subframes installed?
I would love to see a picture on car before I order them.
Along with the torque arm, this might be a great setup for my LS3/80E swap!

 

Just a heads up, JEGS has the umi subframe connectors on sale for $177.09 with free shipping....

http://www.jegs.com/i/UMI+Performanc...400-R/10002/-1

 

Wow! Those look really nice for $177!

I might have to buy these..

 

The only thing I hate about those is that stupid seperate tab, it means grinding the powdercoat and welding, making for an ugly finish. It's done to clear the stock exhaust. They might as well have built it to be bolt in.

 

What tab are you referring to??

 

The little bar with tabs for the passenger side front. Its in the pic

 

Is this the piece your referring to?

http://umiperformance.com/catalog/im...2400af_LRG.jpg

 

Yes

 

Adding my 2¢.Global West along side my pre-Alston SFC.I went with GW because they tuck away really nice, but mostly cause they are tubular...as well.

 

Dang, and I thought I got a deal at $206 shipped.

 

Did you have these stitch welded or just on the mounting points?

 

It's only $29 difference. I'll confirm they are 177.09 shipped. Ordered mine yesterday.

 

Bought a set of UMIs and was wondering if I should coat everything with weld thru primer since I have to get to bare metal on both the car and sfcs? Don't want any rust to invade later on.

 

That's what I do and priner top coat and urethane sealer like for body panels and windshiwlds afterwards. Finger dipped in soap let's you smear it out to a clean bead

 

Thanks. Have never used weld thru primer before, is one any better than the other? How does it affect the welding process, any different than welding bare metal?

 

Hard to tell from the pics, but i did both.As per GW instructions, which are crappy btw.

 

They seem to tuck well, any interference with the floorboards?

 

None at all.Almost like that space was made for them.

 

I bought the Alstons, but didnt get them installed yet. I like that they tie in the subframes directly. How about jacking? From what Ive seen they would provide good jack points for the rear, but how about the front? Or can I jack up both wheels if I put the jack in the middle between the wheels?

 

Yeah, I don't even have a third gen yet, but I've been presearching. So the inners are either Mac or Alston? I can find the Alstons from TDS and Hawks,can't find the Macs period.
I really like the theoretical strength advantage of outers that require cutting through parts of the floors, but what about carpet fit?
I'm also liking the outers that connect to multiple points at either end, but these seem to call for a more traditional exhaust routing, right?

 

Looks like we are in the vast minority in that there aren't too many people on here running the GW SFCs. I love mine. Tucked up under there nice and tight. Fit perfect and they blend in nicely with the undercarriage.

 

are those close enough to be welded to the rocker pinch?

I designed and fabbed my own and added welding tabs so I could do just that. a little dirty from sanding dust etc from paintjob