Changing the Lower Control Arms on a !941 Cad

[Mike Wenrich #1666]

I have been a member for a long time and saved articles on changing the front coil springs and control arms but one part of the advice seems to be missing.  The "Chilton" way of changing the arms seems to be supporting the inner end of the lower arm, removing the four bolts that hold the inner shaft to the front crossmember and then lower the jack until the spring is free of the arm.  What is not mentioned is whether the spring needs to be controlled in some way to prevent it from coming free of the assembly before tension is relieved.

Has anyone done this and would this be a good way to remove the spring and then change out the arm?  My lower arms were rusted and then a plate welded to the bottom.  I have replacement arms to use that are in better shape.

Mike Wenrich

[Brad Ipsen CLC #737]

The proper method to remove the lower control arm is given in the 1941 Shop Manual on page 13. 

[Steve Passmore]

Its supposed to be done by removing the threaded bolt at the bottom of the knuckle support then lowering the jack and the bottom arm until spring tension is released. That way the springs always contained.

[Bill Ingler #7799]

To add to what Steve has said, picture below is my 41 jacked up just before I started to change the left control arm. Jack the left front of the car, on the side you want changed, so that the left front tire is about 3 inches off the ground. Place a floor jack under the left frame just back of the wheel well. Block the rear wheels from moving, remove the left wheel, brake drum, brake shoes and backing plate. Place a  floor jack under the knuckle support and jack up the control arm to put some compression on the spring but not enough jacking to raise the car off the jack under the frame. Remove the treaded bolt from the knuckle support and then slowly lower the jack under the knuckle support until the spring is free of any compression. You then should be able to roll the floor jack out from under the control arm and remove the spring. Reverse the procedure for putting the control arm and spring back in the car. Once you have the new control arm attached to the frame and prior to putting the spring on the control arm, bring the control arm up to the knuckle support to see if the knuckle pin will thread through the control arm and knuckle support. You may need to adjust the shaft on the rear of the control arm to align the control arm with the knuckle support allowing the seals to fit between the knuckle support and the control arm.     Bill

[Mike Wenrich #1666]

Thanks for the replies.  I guess the Chilton way is not recommended.  Seems either way would be the same for lowering the arm but I want to go with the safest way. 

As an afterthought, I believe these are original springs.  I know they have been there for 40 years.  The car sits level but would changing the springs be advised and if so, can we obtain new springs?  I would hate do this job and then drive it ten miles and have one break.  Right now the front end is off the car and everything is easy to access. 

[Bill Ingler #7799]

Hi Mike: If you are going to keep and drive the 41 and especially if you believe everything is original to the car, then I would put in new springs. I would also price out a new front end kit to replace bushings, king pins, shafts and seals. Since you have the front end off the car. what better time to replace parts. I replaced front end springs in both my 41 and 47. A good place to get the springs is Eaton Spring, web site below. Bill

https://www.eatondetroitspring.com/

[Mike Wenrich #1666]

Thank you for the link.  I see they have them and also the rear springs.  I was concerned about those as well because I need shackle bushings but I will have to call about the rear mounting kit and what comes with the shackle kit.  Could not tell if the additional $359 for a mounting kit included the leaf springs.  I would certainly dislike being on a tour with this car and have to drive it with one side low in the rear or front.

I already have the mounting rubber and previously did the king pins so hopefully that will be all I need.

[Paul Phillips]

Mike
If you need pivot bushings then try Rare Parts. I think they supply many of the resellers.  Anyway, their stuff is good quality.

Another thought to consider on front springs is to use a spring compresser that works from the inside of the coil.  The jacking method isn't too bad for removal, but I found it fussy to install the new springs that way. The lower arm is at a very open angle when there is enough room to get the spring in, and trying to install the rubber cushions, guide the spring into the seats, and compress it is a challenge.

Paul

[Jay Friedman]

Another aid to installation and even removal is to follow a Jack Hoffman recommendation.  This is to wrap a chain a couple of turns around the bottom of the floor jack used to compress the spring at one end and around the top of the frame member over the spring at the other end.  This way the spring cannot push up the car.  I did this when changing the shocks and springs on my '49 which has a similar chassis.

[Mike Wenrich #1666]

Paul...I borrowed an inside spring compressor and due to the bulk of the tool, it could not grab the coil firmly on all four arms.  I was certain this was going to be the safest way to control the spring and was disappointed when I could not get the tool to work.  It was after that, I posted my questions about how best to do this.  If the body of the tool was about an inch less, I might have been able to use it.  And then it was going to be difficult to tighten after it was installed.  Maybe impossible.  There are likely proper tools out there but this one was not it.

That is when I revisited the Chilton suggested method and that method was also suggested by a mechanic I know.  He did say that the engine had to installed due to the problem of the spring pressure lifting the car.  My engine is in the car.