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Adjusting front end heigth with shims

Started by Bob Hoffmann CLC#96, February 12, 2008, 04:00:06 PM

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Bob Hoffmann CLC#96

 I have a car with coil springs in the front that sets uneven. It's low on one side by 3/4"  How thick a spacer is needed on the coil to raise  the car level?  I remember some ratio but can't remember where I saw it. Thanks, Bob
1968 Eldorado slick top ,white/red interior
2015 Holden Ute HSV Maloo red/black interior.
             
Too much fun is more than you can have.

Bill Ingler #7799

Bob: Moog made a kit which has the spacers pictured. These are marked 1/2 inch which I believe if placed between the A arm and the spring would raised the car 1/2 inch. I used a similar spacer on my 47 until I decided to replace with new springs. Moog probably made them in different thickness but I have only seen the 1/2 size. I am not familiar with a ratio.

Whit Otis, 1188

Bob,
I had a sagging front spring problem on my '40 formal sedan.  I simply measured what should have been the correct height.  If memory serves correctly, I was short something like 3/8".  However, most limo's always sat high in the rear until you fully loaded them with passengers.  Since I seldom have a full load, and a more level appearance is important when the car is being viewed or driven with two people in the front seat, I took 1/4" pieces of conveyor belt and cut them to fit the upper and lower spring perches raising the car 1/2" and the car looks great.  Bottom line, decide how you want the car to look under the majority of circumstances and shim for that. 
Regards,
Whit
Whit Otis -
1941 6219D Custom
1941 6219D
1940 7533F
1986 Mercedes Benz 560 SEL
1999 Bentley Arnage
2019 XT5
Drawing of AP Sloan Custom by Terry Wenger

Frank Starr

Roughly a 2 to 1 ratio.  A 1/2-inch spacer would typically raise the car 1-inch.  You can do the measurements on the A-arm to get the exact ratio.  It may be low on one side from old collision damage which pushed the frame up a little bit at the coil spring mount on that side.  I happen to have a 64 Studebaker that is exactly that way.  The frame was 1/2-inch high at the left coil spring mount, causing the car to sag 1-inch, enough to notice when you followed the car down the road.  A 1/2-inch spacer cured it.  It lowers the upper coil spring seat 1/2-inch, exactly the same as straightning the frame back to original spec.

Frank Starr
Seattle

Warren Rauch

 You didn't tell us which car your working on or where your measuring the 3/4 inch. So you will have to do the calculation yourself. Measure on a perpendicular line from the lower cross shaft of the A- frame to the center point of the spring, this length a. Now continue on that same line to the point you are measuring the height at ( include  length a ) this is length b.
   Shim thickness = a/b X (error in height)
   If you are working on a 1941 check Serviceman Oct1941 page 39. They tell that a variation of up to 3/4 inch is OK measured at the front cross member. (a later correction says 3/8" on any car side to side) But, that could still be ok if yuor measuring at the fender. Warren

Bob Hoffmann CLC#96

Thanks to all that answered. Warren, the car is 3/4" low on the right  measured from a level floor to the frame just behind where the a-arm bolts in. The suspension has been modified. The difference becomes worse at the fenders & much worse at the tip of the king bee mirrors. It HAS to be corrected. What does a/b mean? Thanks, Bob
1968 Eldorado slick top ,white/red interior
2015 Holden Ute HSV Maloo red/black interior.
             
Too much fun is more than you can have.

Glen

Glen Houlton CLC #727 
CLCMRC benefactor #104

Warren Rauch

 I know I would not try to correct this problem with shims.  This sounds like a bent frame or other parts in the front end. If you do try to correct with shims they would have to space the lower shaft down from the frame. This would likely cause a suspension that can not be aligned or at least not stay in alignment.Warren

Warren Rauch

 I got to thinking on this. If the coil spring is broken on the low side, it could drop it the inch or more it is off at that point. Just  a weak spring isn't likely to sag that much. Warren