I've searched for an answer to this and contacted everyone I can think of about this without any luck. I feel I must have just missed seeing it somewhere here because I know it's been done lots. Or am I just over thinking it? If you're running a banjo axle with torque tube will the torque tube and drive shaft need to be a different length if you remove the centre section of the banjo and add a closed driveline quick change? There was a time when I could do the math and figure that out but that day has long since passed. I do realize the input/torque tube angle will change so I've already accounted for that with some transverse leaf spring mounts adjusted 5 deg. I know everything could be learned with a simple mock up but my shop is so small I can't do that until the spring when I can push the car out and spin it around. Also V8 torque tubes and driveshafts are kind of hard to find where I live. If it's something I need to worry about I have time to search but if it's not an issue I won't bother. Thanks, Shawn
Shawn, all I can tell you is, when building a track roadster for a friend, we used a banjo center for setup and fit the torque tube and rear arms. When we installed a quick change, the torque tube was 3/8" too short. We simply machined a spacer that fit between. Luckily, we hadn't shortened the drive shaft.
I would think you’d have some variation from Quick change to quick change I’m sure there’s all a little different seems the easiest thing could be measure axle center line to torque tube flange on both the quick change and the banjo.
Oh wow ok, that's good to know. Thanks Marty! I think I could probably make up the 3/8" at the coupler when I drill the pin hole position in the lower shaft. I could do the spacer like you did then move the radius rod mount on the torque tube. A second option would be to make it up at the axle spring mounts too I suppose. Most would probably pull it together without noticing the 3/8" I'm sure lol. Stuff to think about.
Yes and you have to also take into account the angles of the torque tube in both cases. The quick change lower shaft is 3" below the original pinion and the angle changes around 5 deg. There is a way to figure it out with math.
Yeah but you don’t see people changing torque tube lengths when they drop a car 3” I guess mock it up and find out. The math will probably just drive you cross eyed and not even be correct when you bolt it together.
I mentioned why the "bolt it in and see what happens" wasn't my first choice. I'm just trying to tap into the knowledge from guys here who've done this to their cars. Maybe everyone's running open drivelines these days or maybe they built their car right from the start with a closed driveline quick change? I know the answer is out there on the hamb somewhere. I really think if it was something to worry about people who sell this stuff would know that it would definitely be a problem. They tell me they just don't know. Right now that's what I'm going with.
I am unsure if this information may help. with a model A when you install a series 101 quick change you are supposed to change the radius rods on the rear axle side for side. Apparently this changes the angle of the pinion and move the pinion face slightly closer to the transmission. Unsure what year of rear end you have and subsequently what radius rods are in use and also if your spring perches are behind the axle or have been converted to over the axle.
Oh really, I've never heard that before. So you're mounting the radius rods on the opposite side so that means they're mounted on the top of the axle then I guess? I wouldn't be able to run that with my setup. I think I'd sooner start from scratch and make new radius rods to fit or I might be able to move the mount on the torque tube. You've got me thinking more about the radius rods though. Those might be an issue that will need to be modified. Their position in relation to the torque tube will change. We'll see I guess. A 1940 axle is in the car now and the quick change will be basically the same thing but 39 bells and axles with 40 brakes again. 39 or 40 shortened radius rods and torque tube. I can't remember. Spring over axle.
I have a build , Olds Powered 29 Roadster, on page 13 it shows modifications to the arms, to match the torque tube angle change.
You build some really nice stuff Marty. Yes that's probably exactly what I'll have to do to match the torque tube angle. Thanks
On my Model A RPU with a S10 4x4 5speed I kept the torque tube to a Halibrand 101 QC. I had to shorten the torque tube and drive shaft, I also swapped the radius side for side and flipped them to compensate for the pinion angle
You were running a stock Model A Banjo with that trans then added the QC after and had to shorten the torque tube again then? Interesting to hear about radius rod swap again. That must be the stock Model A radius rods is it? Cheers,
Yes I used stock model a radius rods, had to swap them due to different pinion angle, also moved the front mounting lug to the stock length of the arms.
Ok thanks, I'm not using any of the stock A stuff. I wanted to be clear that you weren't using the later rods. That's not going to work for me so I'll just modify them for the angle change. Did you need to shorten the torque tube? Not with the initial install of the transmission, I get that but after you were running the stock banjo and put the quick change in? I'm wondering about the torque tube length difference between the stock centre and the quick change? Marty replied above that he found his was 3/8" short. Cheers,
When I built my AV8 coupe I swapped out the stock A rear to a winters with ‘40 rear and shortened the torque tube I can’t remember exactly the amount but the 3/8’s mentioned above would have been about what mine was too( seems like I remember it being about the thickness of the flange on the end of the torque tube) . I also had to change the angle on the rear rods slightly as mentioned above as well.
The model A radius rods mount in the two leading holes at the end of the axles housings. By turning them upside down the camber of the axle changes to the camber required with the lower mounting on the torque tube with the quick change center section.
Thanks! Ya it's been years since I had any of the Model A drive line stuff so I forgot they were mounted on the front of the axle. For years I've bought every good set of the V8 ones I come across so that's just my default now I guess. Cheers,
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