Lowering the rear of my model a. I knewed i can put a model T Spring in it and even revers it. Now i read that it lowers the rear even more if i put a model T rear crossmember in it ? Is this true and does it have the same lenght ? What is involved to do this crossmember swap, besides drilling out the rivets and put now ones in it?
I'm not sure you can swap a T crossmember into an A. Not wide enough. The best way to lower an A, in my opinion is to 1) adjust rear spring and reverse eyes 2) frame height step of the rear frame. (Aka Tardel step) I personally think it would be about the same work to step the rear crossmember vs. Trying to make a T crossmember work.
On my 30 Sport Coupe I stepped the frame using the Tardel book and removed a couple of leaves out of the springs and had to add the leaves back because the wishbones hit the frame. My avatar also had a stepped frame and was running 7:00 16's on 35 wires. The 30 has an 8BA flathead, 41 pickup transmission and a stock rearend with 3:54 gears, I'm running 2:35 75 R15's and you can see how low this got the rearend. I had to raise the rear of the transmission an inch because the rearend was higher than the back of the transmission causing the oil to drain out of the rearend into the torque tube.
Too many variables without more information about what you have got right now, what you are willing to change and how low you want to go.
You can BUT it needs to be a '26/'27 T cross member. If you see them side by side, the '26/'27 T crossmember looks similar to a Model A rear crossmember. This with this crossmember & T rear spring, it lowers the rear by 3"-4". Reverse the main and remove some leafs for even more lowering. I used this set up in my '28 AV8 on '32 frame.
the problem is, in switzerland it is ilegal to step the frame, this would be the best way i know. Even thought about to get a second frame and swap it everytime i have to go to the swiss dmv lol thank you, this was the answer i looking for
Another option without stepping the frame is to use a rear spring from Millworks Hot Rods. This spring is shaped like a Model T Spring (great for a future quick change) but designed for a Model A frame rear crossmember and shackles. I just checked their web page and they are currently on sale. https://www.millworkshotrod.com/collections/chassis-and-suspension/products/av8-hrs-narrowed
So you can swap the crossmember, but not step the frame? That's essentially the same modifications from a "what does it take to do" standpoint.
I also used a '26/'27 T rear crossmember on a model A frame and if memory serves me right, you only need to drill one additional rivet hole. The rest line up with the frame rail "tabs at the back of the Model A frame. I'd assume it could be done without anyone really knowing it was changed.
I just looked and the link and it says out of stock. T rear springs use to be all over swap meets. I always look for them since they are a bear to ship.
Are you allowed to shorten or lengthen the frame? If so, you can run a spring behind the axle. You have different spring and perch options and it can be set up to lower the car. Some have swapped the axle ends around, shortening the frame and the spring is in front of the axle. Mostly, though, people like the spring in back. It's a softer ride.
As Brent said ..... or are you allowed to make a rearwards facing suicide style top spring mount attached to the original A cross member? If so you could then use '35/36 rear wishbones that will lower the chassis position because the shackles are now behind and lower than the original A shackles position. Not ideal engineering wise because of the torsional loads imposed on the original cross member and chassis attachments ..... but .....
I am not an expert in T rear springs nor am I trying to throw shade on Millworks, but I'm not seeing how the spring in their picture is a Model T style with Model A width. The T spring I have in my car looks like a U in the middle and the main leaf sitting a lot flatter. Maybe T rear T springs were different through the years? I dunno know. I don't think the Millworks one just needs to be spread. The overall shape seems different and more Model A like. The one in the Millwork picture looks just like a normal Model A spring. What I am missing? The one in the Millwork picture looks just like a normal Model A spring. What I am missing?
OP, if you go with the '26/'27 T rear spring & crossmember, make sure to get the two forged U spring clamps for it. The T spring is 2" and the Model A is 2 1/4" so it won't work as is or you'll need to shorten and weld the Model A ones which I'd try to avoid.
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