Strut tower brace
03-12-2012, 06:16 PM
#22
I've owned F-bods since 1976, in other words, 2nd, 3rd, and 4th get cars. The 2nd gen cars had 2 flex issues, the flex of the suspension itself, within the subframe, along with the weight of the engine right in the middle, potentially causing the frame to "sag" over time; and secondly, the longitudinal flex between the subframe and the rear floor pan of the car. Keep in mind, only (4) 7/16" bolts held the subframe in place.
Noted GM suspension engineer Herb Adams started a suspension parts business around '76-'77, after he retired from GM. He specialized in 2nd gen parts. One of the structural parts he designed was a brace that attached to the firewall in two places, and one of the upper a-arm mounting bolts. This was to triagulate the front structure, and add some rigidity.
The 3rd and 4th gen cars are very similar structurally, just different in that the 3rd gen cars had upper struts, and the 4th gen cars had upper a arms. Both the struts and a-arms are bolted to a strut/shock tower that is part of the front unibody structure. This structure sees the loads of the front suspension, so if one car would benefit from a :tower brace", so would the other.
If you guys think these braces are something new, Ford started using them in the early 60s, on the Falcon/Mustang/Comet, first as a triangulated brace that went between the firewall and the shock towers, and later, as an additional left-to-right engine compartment brace, in the '64 Falcons that raced in the Monte Carlo Rally.
Noted GM suspension engineer Herb Adams started a suspension parts business around '76-'77, after he retired from GM. He specialized in 2nd gen parts. One of the structural parts he designed was a brace that attached to the firewall in two places, and one of the upper a-arm mounting bolts. This was to triagulate the front structure, and add some rigidity.
The 3rd and 4th gen cars are very similar structurally, just different in that the 3rd gen cars had upper struts, and the 4th gen cars had upper a arms. Both the struts and a-arms are bolted to a strut/shock tower that is part of the front unibody structure. This structure sees the loads of the front suspension, so if one car would benefit from a :tower brace", so would the other.
If you guys think these braces are something new, Ford started using them in the early 60s, on the Falcon/Mustang/Comet, first as a triangulated brace that went between the firewall and the shock towers, and later, as an additional left-to-right engine compartment brace, in the '64 Falcons that raced in the Monte Carlo Rally.
03-12-2012, 08:06 PM
#23
The 3rd and 4th gen cars are very similar structurally, just different in that the 3rd gen cars had upper struts, and the 4th gen cars had upper a arms. Both the struts and a-arms are bolted to a strut/shock tower that is part of the front unibody structure. This structure sees the loads of the front suspension, so if one car would benefit from a :tower brace", so would the other.
You couldn't be more correct. That platform was a floppy piece of junk ... but they look great!
And I've built a couple 3rd gen race cars. What I've noticed about the 3rd and 4th gen platforms ...
The sub frame structure on a 3rd gen follows the trans tunnel. 4th gen front sub structure turns outward and ties to the rocker. Much more stable and adds significant rigidity to the front half.
The 3rd gen has a large hole cut in the top of the inner fender along with slotted holes to accomodate the strut and movement for front end alignment.
4th gen has a solid and thicker, layered material structure on the inner fenders.
While both platforms have the upper mount attachment points at the same place, the 3rd gen direct attachment applies forces almost vertically and directly to the structure.
4th gen upper a-arm pivots in parallel yet different lengths to that of the lower a-arms, connected by a coil-over shock. this uneven movement help dampen suspension travel and shock.
Back in my day, the big innovation was laying down the rear shocks on our motocross bikes. Twice the travel, same shock length, more control. Similar theory.
Big side benefit is that loading isn't vertical, rather more lateral due to the cantilevered knuckle attachment. As the upper pivots up, the force tries to pull the upper out, not up, all the while laoding is dampened by the coilover.
God Bless Herb Adams.
03-13-2012, 05:33 PM
#24
At least my car had the TA 6.6 litre engine. I found out a couple of months too late, that the 455 was being dropped after the '76 model year, so I was unable to put in an order for one. You couldn't do an "internet dealer inventory search" back then, so I took a couple days off of work, and spent them driving to Pontiac dealers all over western NY, looking for a black, "stripped", TA with a 455 and 4 speed. No such luck, wound up ordering the '77.....
Of course, stupid me, I should have bought a '74 with the 455 SD engine. I didn't know about the upcoming SD engine, and bought a new car (Grand Am) in '73, and figured doing a 1 year trade wasn't a good deal, economically. So I thought I'd wait and order one in '75. Yeah, right......
03-14-2012, 09:30 AM
#25
TECH Junkie
iTrader: (17)
Join Date: Aug 2006
Location: Rapid City, SD
Posts: 3,161
Likes: 0
Received 0 Likes
on
0 Posts
I can understand the argument of a valid chassis stiffening component, but thinking that it looks good is different. They clutter the engine bay and do not offer any visual appeal, IMO.
I bought my old 97 with a tower brace, and gave it away because I thought the car felt better without it.
I bought my old 97 with a tower brace, and gave it away because I thought the car felt better without it.
