73 SB Spreader Bar Concerns
 

Purchased a spreader bar for my 73 SB.Have figured out the install.With the stock fan in place i'll have to lower the mounting brackets for the bar about 1/4" off the flat bar .Read a few threads on cracks showing up on the towers after the install of the spreader bars.Any one have any thoughts, my car is a DD no racing no motorcross.Is it worth the possible trouble. Only looking for a better ride with some improved handling. Thanks for the info

I installed one on my 69 BB vert, along with the rebuilt front suspension it has made a difference, less cowl shake, and the car seems to track better on the road.
In my opinion, a worth while investment.

If you can tell the difference on a car being driven anywhere close to legal limits, you've probably got a weak frame.

well, my 70 coupe used to push like a dump truck untill i put a spreader bar on. now it's silly loose in the back.almost looped it a while back getting on it in a corner.i'm gonna losen it up a little to correct this. worthwhile investment. YES.

The spreader bar just stops most of the flexing at the top of the frame where the upper A arms attach. This can be significant but the whole frame flexes a lot. With your car running turn your steering wheel back and forth and watch your engine move. This is because of the frame rails moving, you see it at the engine mounts even with a spreader bar. The spreader bar is not going to crack your frame. My guess is the people you found cracks already had them. My suggestion is to tighten the bar by pulling the frame inwardly, not pushing it outward. This should help a good frame not crack in the future. Also on a race track this reduction in flexing of the frame is very noticeable.

Any time you can strengthen a body on frame car with additonal support you will notice the difference from a variety of perspectives, not just in racing. Corvette bodies offer no real structural support to the frame like a true body on frame steel car-the reason for the very heavy frame-however, attempting to prevent frame flexing through essentially one plane-horizontally in the case of the vette (the passenger compartment as well vertically)is only going to be of limited success. The front tip of the frame is pretty much only tied to the main frame through the lower horizontal brace. It will flex under any normally driving-road bumps/irregularities, engine torque, and suspension movement-at legal speed limits! Why do convertibles flex more than coupes-no upper cross bracing. How do I know this?

Every car I have owned in the last 10 years I installed some sort or strut tower brace or in the case of the 1994 Mustang GT convertible (subframe connectors underneath the car). Today's unibody cars are MUCH stiffer than the 63-82 framed vettes and even on my 2001 pontiac grand prix and 2008 Chrysler 300, adding strut tower braces significantly changed multiple characteristics of these cars:

1. Car is generally tighter (less squeaks)
2. Handling noticeable improves since there is less chassis flex before the suspension can react.
3. Steering reponse noticeable improves.
4. The car rides better-less flexing of the chasiss

These changes are on new cars guys! Think what it will do for your vette.

I can't say that mine made a great deal of a difference but honestly I just cruise in-city and on the highway. It can't hurt (I have never heard of frame damage attributed to one).

http://img.photobucket.com/albums/v1...reader-004.jpg

spreader bar
 

Hi Paul I see you installed a bar with stock fan.I am considering the same on my 74 with a stock fan.can you still change belts with out removing the bar? John

Good question! I hadn't thought of that and my car is not at home so I can't check the clearance, bar to fan housing. But in any case one side can be unbolted in less than a minute and the bar dropped down

Don't mean to hijack but I must have read the directions upside down. Anyway I have my Vette on the ground and tighten the spreader bar so it pushes against the towers not pulls them in.

Am I doing it the wrong way ? :cheers:

Me too. I have installed 3 of them this way. Am I doing it wrong also?

Are you saying that you can move (pull in) the towers by adjusting the bar?

For you guys like Paul that installed a spreader bar on small blocks with the OEM mechanical fan, I have a had a VBP spreader bar for years and have never put it on my 78 since i am just not real comfortable having the 90 degree mounting brackets welded to the straight steel piece that connnects to the upper control arm-the clearance to the fan blades and other accessories seems too close for comfort. How close is it on your cars with mechanical fans and how did you get the measurement perfect and welded so that there were no clearance issues? Thanx.

I pulled the frames together to increase the amount of negative camber, got another .5 degrees. Once the bar is tightened it probably doesn't make much difference, it just becomes a support.
I ran my bar with both stock fan and electrics. I had it welded lower for clearance, doesn't need much.

With respect to VBP I could not figure out their installation with stock fans so I went with another product (a Forum sponsor as well) that did not need welding. Since my choice is a Forum sponsor I can post a link.

http://speeddirect.com/index.aspx?nodeID=183

http://img.photobucket.com/albums/v1...derarm-009.jpg

Things are close but I did not have a problem in 2010.

http://img.photobucket.com/albums/v1...barD-001-1.jpg

If you are installing the tie bar with a stock fan and shroud, a 3/4 in dia. bar needs to be centered approx. 1in,below the bolt centerline of the upper control arm mounts. It should also be slightly foreward of the same two bolts front to back. This puts the bar in close proximity to the fan pulley, but any torque from the engine will be rotational, and twist the pulley away from the bar.
The commercial welded units I have seen have the bar centered vertically with the a-arm mounting bolts and mounted over the front mount bolt. They can't be used with a stock fan and shroud.
Mine is home made, is close to the pulley, but I have not had any issues since its install 4 years ago.
As to its effectiveness, I did find that it helps take some of the front end flex from the car when crossing dips, bumps ect.
http://i42.photobucket.com/albums/e3...e/100_0296.jpg
http://i42.photobucket.com/albums/e3...e/DSCN0044.jpg

If a sponsor, how about a name?

No I can't even jack up the back wheel without the front wheel coming off the ground.

The spreader bar on mine is installed so it pushes against the shock towers instead of pulling them in and I would like to know which way you are supposed to do it. :thumbs:

Thanks Paul for posting. I did not know that there where bolt on solutions for stock fan setup which is why I have not installed a spreader bar. I'll take a closer look at this solution.

I've very sorry. I do not know what you mean. I just tightened up the bar against the A-arms and left it at that. Nothing will move in or out in that configuration.