Hmmm... Been thinking about my front crossmember and sorting it out since getting the frame sandblasted. It is currently bolted in (badly) and I am seeing suggestions in two different HAMB threads that oppose each other. a) Weld it in and b) re-bolt it in, (to retain chassis flexibility). Regardless as to the method of fixing (which IS the preferred route?) I seem to recall hearing that adding in castor at the wheels can sometimes cause spring bind. As the original front crossmember is installed vertical (effectively 0 degrees) I guess. So, am I on the right path in thinking whether I weld or bolt, I should slope the front crossmember to achieve the same'ish castor, so that when I put the front end together everything is inline with each other? Hope I explained this clearly. I am guessing this is one of about 10,000 things that you don't think of until you actually embark on building a rod. I know it never really occurred to me! Paul
You are going to get opinions all over the place on how to do it the right way, here is mine. The model a frame under my 27 has the crossmember fully welded. The frame is completely boxed, and I made custom crossmembers not only under the transmission portion, but I am also running a tubular crossmember underneath the motor. The frame has zero flex and I wanted it that way because I am running a fiberglass body and they can't handle twist and flex. The theory that Henry built them to twist was mainly because of the dirt roads of the day, where a flexible frame allowed the car to keep all four wheels on the ground. On todays roads that flex is not needed IMO. As for angling the crossmember to better match the caster angle, it is a good idea but I didn't do it on mine. There is a slight mismatch in the angle of the spring to the axle but it has never been an issue. The shackles are very slightly twisted from that mismatch, but the bushings hold up fine and the car rides better than you would ever expect. The car has been on the road for 25 years with no handling issues ever. In rod building there is the "perfect world" and then there is the "real world". There are a zillion hot rods running around with things done to them that some other people would say are not right, but somehow they go down the road and handle and perform very well. It is too easy to get hung up on this opinion or that opinion, you just have to do what seems right for you. Don
Don Many thanks for taking the time to pen that, appreciated. I have been accused of getting hung up on details on other projects in the past. I guess the issue for newbies like me is knowing when a detail is critical and when it can be ignored. I am sure there are issues like this that can safely be sidestepped/ignored and other times when failure to attend to something can result in a dangerous ride. My guess is I will test people's patience in the coming months/years by asking about each issue rather than assume. If nothing else it will hopefully provide useful content for other people scratching their heads and thinking the same question. I am sure there are many members here with thousands of posts to their name that will read these questions and think "sheesh, is he serious, it is SO obvious...". Trouble is, I suspect there are an equal number like me that just don't know and for those, this thread might help. Again, thanks. It is input from guys like you that help guys like me. Paul PS: Oh and I do agree, perfect world versus real world.
I think rule of thumb is that if you make the frame more ridgid by boxing then you can weld the crossmember in place, lots of people prefer the rivet-look. The crossmembers i have measured have the castor made into them - i did exact measurements to do the frame in autocad and that is when i learned it has 5-7degrees as part of the stamping - makes sense when you think about it. Its easy to measure it.
I hope you didn't infer that I was implying you shouldn't ask questions, just the opposite, you are doing the right thing. Even if someone has played with these things for lots of years you still learn something every day that you didn't know before. Oh, by the way, you will be trimming the back edge of the front crossmember off as it won't be needed any more and will be in the way of your new crank pulley. Just trim it so the back looks like the front. Don
Wex, My frame is also boxed and the the front member welded in. Most beam axles run at 5-7 degrees camber and depending on your tire size(s), it's best to set this with weight on the front to get to ride height. I moved the front x-mem forward since I'm adding a y-block and the frame starts to narrow and curve down a bit. I assembled my spring, axle, radius rods,x-member in the (leveled) frame and put jack stands under the axle. Carefully added an engine block on top w/ 2x8 supports doubled up to get the spring loaded. Measured, set the tilt as far as I could and measured the angle to make sure it was even on both sides. Then tacked it to the frame. Once I boxed the rails, made motor/frame mounts, Dagels x-member, set the motor, etc., I'll be at about 4-5 degrees with big and littles. Not on the road yet, but it should work. Now I've had the short block in and out of the frame about 30 times to get it so it fits (I hope) so we'll see. I think they also sell adjustable perch bolts to reduce/eliminate bind.
oj, thanks, I thought original As had zero caster. Must have read that wrong. I will go look. Don, no not at all. Didn't for a second think you were implying anything. thanks for the rear of crossmember suggestion. I was thinking the same thing. Paul edited to fix typo...caster as opposed to camber!
You might want to consider just notching the rear of the stock x-mem. They need as much strength as they can get. RB
I welded the crossmember in the Model A frame that I did back before the internet. I torched out the rivits and used a simple gravity angle finder to set the crossmember at five degrees. Now that everyone has access to the internet I have found that I maybe should have angled it back at seven degrees, that would be about five degrees for caster and a couple more degrees for "rubber rake" on the chassis. I am currently building a '32 chassis for my coupe using repop deuce rails. The repop front crossmember that I welded in my current chassis had seven and one half degrees of caster built in. You are welcome to check out the the build albums on my page if you're interested. Lots of build threads on the HAMB, learn to use search, usually less is more...
Welding is fine if you box the frame, I riveted mine back in since I'm running a flathead and didn't box the frame. If you weld the front crossmember in on a stock frame they flex and will crack the frame.
Don is correct here, there is not good reason in the world to not ask a legitimate question. I also agree with Don on welding the cross member, his logic is good and I personally prefer to weld them as to bolting or riveting. The only thing that I would add is that you are head of the game if you make sure that everything is pulled up tight prior to welding. As for angle a stock Ford cross member has the angle built into it for stock ride height. Now in a perfect world you would have your chassis set to the exact stance that it will have when completed and the angle built into the cross member will be the exact equivelent of the caster angle of the axle. That said a degree or two off is not going to cause spring bind that you will ever notice. The Ford suspension is very forgiving, it had to be as it was a mass produced automobile. Close is cool for a hot rod.
The Jalopy Journal
