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Subframe Connectors on a 67 convertable

sbc subframe bmr

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4 replies to this topic

#1 jbleeg

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Posted A week ago

Doe anyone have experience with BMR subframe connectors on a 67 convertible?  I am trying to eliminate some of the Cowl Shake associated with these (convertible)  cars and am wondering if these will help reduce Cowl Shake. I have done most of the usual things on the car like Shocks, Front and rear Heavy Duty sway Bars, Rubber front suspension bushings, and recently updated the rubber body mounts to Urethane body mounts by Energy Suspensions. My car is a cruiser with a 326 and a turbo 350 AT. It does not see drag racing, or Track days, but does see some spirited driving. I am just so annoyed by the shakes and probably spoiled after driving my modern era BMW.

 

https://www.summitra.../model/firebird

 

 



#2 NOT A TA

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Posted A week ago

If you're going to put sub frame connectors in you need to put solid body mounts in. Do you have the cocktail shakers in?


John Paige

Lab-14.com


#3 jbleeg

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Posted A week ago

Yes to the original Cocktail shakers. Why solid mount?. Seems the uerathane body mounts I just installed should be plenty stiff. I am not trying to race the car. It is just a cruiser and I am trying to lessen cowl shake and shudder. Anyone have a opinion? Do this help convertible and cowl shake?



#4 Brownie1981

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Posted A week ago

The solid bushings really work best with sub frame connectors since they eliminate body flex, something that rubber and poly do not do as well. Some will tell you if you go bolt on SFC you can go poly, if you go weld in SFC then go with the solids.


--------------------------
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Link to build: http://www.speedtech...prod/prd287.htm

#5 NOT A TA

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Posted 6 days ago

I've done poly with bolt in connectors the past and doesn't work over time. Initially they seem like they're OK but over time/miles they fail. The polys deform and rather than rebound like rubber they stay deformed (pic below). You'll keep tightening the sub frame bolts when checking over the car and finding them not up to 90 lb ft.   Eventually you'll probably get creaking from the bolt in connectors.

 

Cowl shake can be caused by a number of different things. Shifted tire belt, wheel balance, axle bearing, wheel bearing, bad shock, driveshaft balance, control arm bushings, control arm mounting points, rear spring bushings, U-joint, and things like worn engine and trans mounts can all cause shake. Sub Frame connectors are more likely to enhance any mechanical issue rather than cure it.

 

Some things occur that can cause a shake you wouldn't think might occur. As an example; I've had tires rotate on the rim from hard braking and drag type launches. That threw off the balance of the wheel/tire combination enough to cause a slight shake. I now mark the tires/wheels on the inside so I can see if a tire rotated.

 

20161123_162516_zps1vyxg07y.jpg


John Paige

Lab-14.com





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