Hey guys,

Right now I have MAC subframe connectors on the car. They attach on the inside of the frame (not like the Spohn ones, which are outside the frame rail).

The car's chassis stiffened up SO MUCH when adding the MAC connectors, that it felt like I was on rails afterwards (when changing laned it was incredible!)

I was wondering if I could add a second set of frame connectors on the outside of the frame rails (such as spohn, UMI, etc.)? Spohn tells me there will be a night and day difference... My mechanic says that it won't change anything but make the car heavier (spohn is about 15lbs a set i think). I know that the outboard frame rail connectors are a good way to jack up the car too...

Is it worth getting both of them? I'm not making crazy power either, but i am making decent power (271hp, 354 tq)... Will adding a set give me better handling, stiffness (too stiff?).

What are your thoughts/opinions?

Thanks,
-Marc

 

Alot of people get UMI, Spohn, or BMR connectors, which run along the outside of the frame rail and the Allston ones which connects the rear and front subframe. I have no experience with the MAC ones but im assuming that they connect much like the Allstons. There are benifits of having both set, you chassis will be very rigid, better in corners etc.

 

Yeah they're pretty much the same as the alston ones from what i've seen... They do hang low like the alstons too, but from what i hear these ones do offer the best rigidity... But if you say this then having inner AND outside frame rail connectors will improve even more then i guess it is worth the 240$ for black PC ones.

Also, is it normal that when my car is on the lift it seems as if the front is hanging more and the doors are difficult to open and close? This is WITH the mac connectors... If I install the Spohn's then will this make my car not bend when on the lift?

Also, do the Spohn's have to be welded to the floorboards and does that actually make any improvement? That seems useless considering the floors are weak metal anyway... right?

 

I have t tops and was wondering if this would be a good idea for me. I have the TDS frame connectors but Im not sure if its enough. Especially because I plan on swapping in a 350.

 

TDS connectors are the same as MAC (inside the frame rails, connect near the crossmember to the back) so we're in the same boat. I would think that it would give better rigidity but i would like confirmation (for example if it only helps if you have 1000hp and are launching the car, etc.. then i won't bother to install a second set)

 

Ive had Spohn...and I now run UMI. Spohn's are harder to weld on only in the respect that its tubular steel. Also I didnt love how the fronts of the SFCs welded on. The UMIs are easier to weld on, because there are tabs. You burn the tabs on and thats it.

That being said...the Spohn pieces were much stiffer in my opinion. You weld those along the pinch seam, and I welded mine to the floor as well. I got ZERO creaking, and hardly any chassis flex with those. Also with the car jacked up, the nose didnt seem to sag to the point where the doors hang up.

With the UMIs....they are further away from the pinch seam as well as the floor. So welding them there takes more work. Also when i have jacks under the front subframe, the nose will sag enough to make the doors not close correctly. Im not sure that this is directly related to the subframes though. It might just be something we have to live with, unless we add more tubing elsewhere.

Im my opinion, if you can fit two SFCs under there, go for it. Im still thinking about making a set of Alston style connectors for mine. I want to make a set that fits a bit different.... more of a reinforcement than an SFC really. The stiffer the better with these cars. Again..just my opinion.

J.

 

Then I think I will indeed go with the Spohns! Nose sag is just terrible to look at when it's on the lift... I'm just imagining it splitting from the car and falling off! (I know that's probably impossible, but just the creaking when going up the lift is enough to scare me!). Even with the MAC (like the alstons) connectors, the nose sags still and it creaks going out my driveway, although it is 20 times better than without it, i can definitely see improvement. I called Spohn and they said their connectors are 15lbs a set, that doesn't seem too bad since the weight is low and in the middle of the car, not in the front, and i will offset that weight by putting in 4th gen seats, so it shouldnt be that bad.. Anyone know if they are indeed 15lbs a set? And when welding on the Spohn's i will take it to a professional garage to do this, so do they have to take out the interior carpet to weld it? I've heard stories where welding these on melted wires and carpets inside the car, any truth to this?

Thanks!
-Marc

 

Is weight really that important to you? If they are 15lbs or 20lbs... The benefit of having a stiff chassis will out weigh the minimal gain in weight. If you have a car that runs well, it wont notice the extra weight...but it will notice the stiffness. Ive found that building a performance car is a give/take type situation. Sometimes the parts you add add weight, but give you a nice performance gain. Sometimes they loose weight and add performance... Its a fun game. haha.

As for welding, I highly recommend removing the passenger seat and both door sill covers before taking it somewhere. Then get some pieces of 2x4 to jamb under the carpet to keep it off the floor. As long as they pay attention to what they are doing, you'll be ok. They should have some spray bottles to quench any hot spots too. Anytime you weld to the floor you will make the other side of the floor super hot. If anything is touching that spot..it'll melt and possibly burn if on too long. So why not take the extra steps to make it less of a chance. Only takes a few minutes to pop out the seat and the sills. You can leave the driver's seat in...I seem to remember Spohn's crossbrace welding up in the footwell area more.

If you are getting the SFCs in raw metal, Ide spend a few bucks and get some GOOD weld-thru primer. Spray them real good...that way when you paint, the areas you cant get to are atleast protected. I painted mine with Por-15...since there was a bunch of welds, and bare metal areas. Just globbed it on.

J.

 

I don't mind the weight so much, I know 15lbs is not much but if it is for nothing then i wouldn't bother, but if you say that adding a second set like this will make it stiffer and give the car a more rigid chassis then i'm all for it, no matter what the cost. This car is important to me and i treat it with lots of respect.

So I'm gonna take out the seats, the door sills and pull up some carpet as well before I bring it... What about wires? Will I have to watch out for those too?

And I will be getting the black powder coated ones. An extra 50 bucks and i don't have to worry about rusting.

 

I cant say for 100%...but Im guessing you'll feel atleast alittle difference. Like I said, my Spohn SFCs made more of a dramatic change than my UMI ones.

The only wires are over on the driver's side. I didnt have any issues with mine that I can recall. Again...the shop should use their common sense and make sure the wires are ok during welding. Unless you want to pull the wires up and prop them out of the way.

I wouldnt pull too much of the carpet up..just slide the 2x4s under the carpet to keep it away. Of course...they should still keep an eye on it.

Its really not too big a job. I couldnt find a shop that would reasonably do the install and that had a drive on lift. So I welded them in myself with some heavy tack welds, then took it to an exhaust shop for final welding... They put it up on a finger lift and burnt them in the rest of the way.

J.

 

Bump! Try a triangulated strut bar like the ones from Spohn and edelbrock.

SFC's only extend upto the foot well / firewall area so you cant expect them to support the entire nose section alone, it's a huge amount of weight acting through a lever to distort the floor, rocker boxes and SFC's. And that leaver effect works both ways, a tiny bit of deflection at the firewall/foot wall area equates several times the distance measured at the nose.



I also know of several imports that use a triangle shaped piece that goes under the fender. It attaches to the hinges and to the frame horn somewhere over the wheel.

 

Hey Is Six,

A triangulated strut bar from my understanding would be to have less strut tower flex (from side to side) during a turn... Edelbrock's strut tower brace looks weak where it connects to the firewall.. Those small little bars don't look like much and they don't connect to the frame, they connect to the strut tower no?

There must be a way to fully connect our car's frames together... I think I will go with the Spohn's... Has anybody one here done these two together before and was there any difference?

Thnx!

 

Sure...there's a way to connect the front and rear SUBframes together. It just takes a welder and lots of metal. A unibody car is meant to work as a whole. Trying to make a unibody car act like a full frame car takes a lot of modification. You basically build a chassis to compliment the factory chassis.

In my opinion...there isnt much need for it.

However...the idea of running SFCs along the pinch seam and welding to the front and rear subframe areas (spohn) along with running a SFC inside of those (alstons) is a good idea. People have done it. They've reported the being VERY stiff afterwards. You can also get really good results from a good cage that incorporates the SFCs. Not always practical for street driving.

For most of us, one set of SFCs is plenty. If you really want to add the extra metal, then running two sets will certainly stiffen things up. But thats as far as Ide go for a street car. Unless you are doing wheels up launches all weekend long...but then you already know what you need to do to stand up to that abuse.

All depends on what you need your car to do really. Just be honest with yourself. Sometimes overkill isnt a good thing.

J.

 

Cool cool... So I think I will get the Spohn Connectors then.. From what I understand they will make the car stiffer but be good for the street... If that's the case then I will get them and weld them all along the car for optimum rigidity...

Today I was pulling out of the driveway and there's alot of creaking when going in and out and since I go diagonally in and out (so that the car doesn't rub on the pavement) there's a scary sounding creaking coming from all around the car...

I hope that this will help in stiffening the car more!

Thanks!
-Marc

 

hellz_wings... howd it work out? did u get the second set of sfc's and have them welded in?

can u post pics please.. i have been running the alston ones for 3 yrs now.. but only bolted in, i pulled the carpet and interior out of my car today, and plan on taking the car to a chassis shop to have the alstons welded in, but when i stumbled on this post, i thought about getting a second set and having them put in. (umi or spohn) but wanted to see how it went for you. please post pics, remarks, and cost of the project, and the results.

thanks!

 

Hey,

The install went great... Brought it to a shop tho.. They did a wonderful job. The pieces are a great fit and finish. They really do not show like my mac ones do (you can see them from the side of the car). They tuck right under there and do not intrude anything but are very close to my y-pipe near where it connects to the car (I have edelbrock headers). They don't touch tho... And i've yet to hear it vibrate on it.

Performancewise, they do make it stiffer. Turning, definitely! It feels so snug in the corners and not creaky.. More responsive. I have t-top car tho. No rust at all. Creaks less when going up diagonally over a sidewalk into the driveway. Still a bit of creaking going on that i can hear from the top of the car but it's a t-top car so you can't do much! I guess only a roll cage would 'fix' that but who cares it's not a big deal. It's hardly noticeable now and it's very stiff now. And you can rest assured that no twisting will happen.

Here are some pics:

https://www.thirdgen.org/forums/susp...-subframe.html

Go to post #46 I have about 5 pics posted of how it looks under my car. You can see the two of them side by side... Got those snapped quickly when i brought it to the alignment shop. Will take more next summer.. I'm gonna coat the whole underbody with black paint.. Detail it a bit and get rid of any rust there is.

Later,
-Marc

 

here are mine


2frame.jpg?t=1252622441

2frame2.jpg?t=1252622506


2frame3.jpg?t=1252622561

2frame6.jpg?t=1252622689

 

i'm running the UMI/MAC SFC setup, i can tell you that the umi are stiffer than the spohn SFC due to material size shape and weight, but the fact that they are so heavy and are a bit of a pain to run pinch welds down the sides make it a toss up, the nose will sag when jacked up from the middle, unless you run pinch welds along the length of the connector. i Don't think the UMI's connect the passenger side SFC into the front of the subframe as well as the Spohns due, i still nedd to make some custom braces to tie the passenger side SFC into the actual inside fraim rail of the car. but it's hard because thats where the CAT/exhaust is.
the pinch welds made a hudge difference then after i added the MACS i can nowlift 3 tires of the ground with the jack anywhere under the car, steering response improved greatly. i'm now looking into adding a "X" brace between the mac conectors,



even if the SFC weighed 75 pounds the benefits would still far out weigh the the added weight.

 

chassis flex is by far the worst 3rd gen fault...
-fixed mine back in 1994-95: built stout sfcs from 2x3"
3/16 wall steel tubing(had a little clearance trouble at
the RH front with the exhaust),boxed the tranny
x-member,added extra gussets at the lower front of
door openings,welded the door opening seams from the
added gussets to halfway up the A pillars. Also the front
structure of the thirdgen is prone to "matchboxing" just
drive a third with the hood off and watch the radiator
support jiggle independent of the cowl as you drive over
rough ground Made some struts out of 1"tube from
the corners of the radiator area to the shock towers,
3/4x2 1/2 struts from the towers to the firewall seam
which was reinforced,an extra crossmember was added
under the fan shroud(those with electric fan could add
a stout x-member between the frame rails just behind
the fan to eliminate delection) Really nice to have a
rigid chassis!

 

88fastgta has the UMI/ALSTON combo, whereas I have the SPOHN/MAC combo...

They both look good IMO. As to which one is better, well, that's probably impossible to know. I know mine was stiffer when I added the Spohn (I started with the MAC one welded on).

Also, I agree with the above statement that added stiffness on our cars is worth the extra 20lbs or so.

Later

 

i have bmr/alstons.... yes they do add weight but i just removed my front bumper support which is heavy so that takes care of my alstons......

 

Oh, the steel front support? How much did that weigh? I heard that some cars (I think the 82-84 cars) came with the aluminum support? I'm assuming with or without this the car will still crumple in a crash? Great idea to get rid of weight over the nose!

I'm doing battery relocation and removing spare, as well as 4th gen seats so that should equal the weight for both frame connectors!

I'm curious about the front bumper support tho..

 

i used to have the Alston Racing inner connectors and was moments away from ordering an outer set from UMI, BMR, or Spohn.. but when i took my car to a pro chassis shop, they showed me a S&W racecars kit. i went with that.

for pics and info click the link below
https://www.thirdgen.org/forums/susp...rame-into.html