Spreader bar geometry, alignment, etc
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,655
Likes: 19
Spreader bar geometry, alignment, etc
I've got a 68 convertible, it has the well known cowl shake, probably made worse by the elimination of one of the few dash supports by adding Vintage Air.
It's also lowered about two inches, springs cut by previous owner. So now there are almost no shims in order to get the correct camber. Probably some frame sagging issues contributing too.
So I'm considering a spreader bar to help in the cowl shake and prevent further sagging an no capability to correct the camber.
So my questions:
Will a spreader bar help with cowl shake issues? If not the offset upper control arm cross shaft will give me the alignment adjustment I may need.
Are the spreader bars designed to have compression stress while the car is static? If so, how are alignments done with shims?
My car also has an LS swap, so if I add a spreader bar it will need to be forward of the upper control arm shaft mounting bolts centerline by about 1.5" to clear the LS1 water pump pulley. All the spreaders I've seen are centered. Will having the spreader off center significantly affect caster/camber during deflection, compared to a centered one?
It's also lowered about two inches, springs cut by previous owner. So now there are almost no shims in order to get the correct camber. Probably some frame sagging issues contributing too.
So I'm considering a spreader bar to help in the cowl shake and prevent further sagging an no capability to correct the camber.
So my questions:
Will a spreader bar help with cowl shake issues? If not the offset upper control arm cross shaft will give me the alignment adjustment I may need.
Are the spreader bars designed to have compression stress while the car is static? If so, how are alignments done with shims?
My car also has an LS swap, so if I add a spreader bar it will need to be forward of the upper control arm shaft mounting bolts centerline by about 1.5" to clear the LS1 water pump pulley. All the spreaders I've seen are centered. Will having the spreader off center significantly affect caster/camber during deflection, compared to a centered one?
Safety Car
Joined: May 2004
Posts: 4,363
Likes: 1,588
From: los altos hills california
The spreader bar should mitigate camber changes under load. Hard to imagine that an offset bar would cause much caster change. What is your thermostat cover like? The hose needs to go around the bar somehow. Check this picture
Having adjustable upper arms means shims are not required so you don't have to adjust the spreader bar with each alignment change.
Don't know what causes cowl shake but it seems unlikely a spreader would make it worse.
Having adjustable upper arms means shims are not required so you don't have to adjust the spreader bar with each alignment change.
Don't know what causes cowl shake but it seems unlikely a spreader would make it worse.
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,655
Likes: 19
Yeah, looked at the adjustable upper arms. Is the spreader bar under compression at rest?
My thermostat is a clockable aftermarket. The issue is I'm running truck spacing with the standard plates. So the bar would have to fit between the pulley and fan.
My thermostat is a clockable aftermarket. The issue is I'm running truck spacing with the standard plates. So the bar would have to fit between the pulley and fan.
