Sorry if this has been kicked about before. I have a 39 tranny and a 48 pickup tranny with the open drive line output shaft. I want to run an open drive line. (Converted 40 rear end) So to install this in a 33 that has the original closed shaft, I need to use the 48 pickup open drive line components behind the 39. I know its been done but never knew the combination. How do you use the 33 tranny mount in all of this? I would rather keep the original mount and not hack on the crossmember. Thanks
You cant use the original 33 mount if you are doing the open drive line. the original 33 mount bolts to the cross member and then the clam shell goes over it on the other side. The open Drive rear mount is required to use the 39 trans (as an open drive) and it uses the biscuit type mounts that all the trans missions use from 37 up to 48 ( 52 for trucks). you will have to modify the center cross member to take the later truck mount to use the open drive set up. or if you already have the 40 rear, you can shorten the torque tube and drive shaft and use the stock 33 rear mount with out cutting anything up. if you have the original 33 rear, you can even use a conversion coupling to go from 10 to 6 spline on the drive shaft and use the original 33 34 drive shaft in the shortened torque tube on the 40 banjo. That's how I would do it. A closed drive line is pretty nice once you get used to working on one.
Then with open drive you must add a torque arm from the top banjo bolts to pivot down at the universal joints. This arm is not needed on parallel rear springs. Believe me you do need the torque arm. Unless you were going to a T5 transmission , personally a lot less work to stay with the torque tube. Though you may have better reason to change.
I appreciate all of the info. Makes sense. I wonder why then, that a casting hasn`t been developed for the back of the 39? Really this is all about removing the stock 33 mount and provide the stock insulator a pad and incorporate a rear bushing bore and seal to hold the open drive shaft yoke.
Annoying question...if you have early Ford trans and rear, why use open drive and have to jury rig new suspension locating system and trans mount? Only reason for going that way that I can see is to swap to a trans that is stronger, cheaper, and has more speeds. Your original system is perfect for what it is and you are introducing complications that offer no benefits. If changing you should IMHO use the changes for some reason, like a 5 speed or an automatic. The changes by themselves offer no benefits that I can see.
What do you hope to gain from this vs. just taking the open drive converter off of the 40 rear and using a torque tube?
If you use the stock type parts it just makes it easier over all. If you are using an early ford style trans, it is an engineered part of the rear suspension. by using the stock components it all bolts together, articulates properly and really rides very smooth. By going to the open drive you now have to reengineer the rear suspension. The ope diff banjo's were used on trucks with parallel rear springs, there was no need for a torque tube, the springs transferred power to the chassis. by converting to the open drive banjo and using a 40 rear, you have taken all the engineereing and tossed it out. the wishbones were never designed to take that kind of force, the torque tube did. by eliminating it, you now have to either modify the wishbones into ladder bars or add a torque arm off the center of the diff. or just mount the whole thing with aftermarket or home spun ladder bars. install the mounts for the ladder bars/split wishbones, reinforce them, and you still have to convert the original 40 banjo over to open drive. If you going to do all that work, just put an 8 or 9 inch rear in it on ladder bars. it will ride the same and cost less than doing the way you are discussing. plus you don't have to worry about breaking an axle in the banjo. if you collect the right parts and pieces, you can bolt the 39 trans to the 33 isolator mount, bolt the 33 drive shaft to the 40 banjo, and the only real fab work you have to do is shorten the torque tube. Which is not tough at all to do. with all the parts in place this is a weekend project start to finish. and for way less than you might think. Plus it will bolt in and look, and work as it should.
I truly think a torquetube rearend is simpler and stronger than any other type of rear axle locating system. Why mess it up?
i agree leave it torque tube I have three cars that way , however it can be done with early ford parts but you will not have a speedo drive what you do is get the open drive housing and there are 6 bolts that hold it to the trans same as the 33 type ,you then cut the open drive housing so all you have left is the part that the 6 bolts go through and the housing and seal area it has to be made small enough to fit inside the 33 mount then get some slightly longer 5/16 unc bolts and bolt it all together ,you have to also plug the speedo drive hole and it all works belive me it works I did this with a car fitted with a 9in diff on parallel leaf spring . woops I'm assuming that you have the open drive rear shaft in the trans for a slip yoke a manual customline one fits I think
Nailhead and patmanta…..You mention "bolt the 33 drive shaft to the 40 banjo". Then I guess you would be adding spring mounts and 33 radius rods to the 40 rear end? By the way, the reason I would swap out the 33 rear for the 40 is strength vs. the 33. tub1....I have a pickup tranny with open drive parts and the 40 rear has my convertor mounted. The 39 pass trans has not been altered yet. I think I read years ago about what you described in an old rodders mag. I believe the crew was adding a 55 BOP rear. I think the emphasis was on getting a cheap strong axle with road gears or many assorted ratios. (yea I know. The tranny was still the weak link) Still like the idea of a 40 rear end even with the closed shaft. Shortening not the issue. Just need to figure out adding the axle spring perches and 33 radius rods to the 40. I never had the 40 drive shaft so more issues.
You can install a 40 Ford rear end and spring in a 33 Ford - just have to make some modifications to either the spring or the crossmember. On my 33 shown here the crossmember has been widened in the centre to accept the 40 spring. Another method is to shave both sides of the spring where it fits into the crossmember - take off about 1/8th of an inch on each side. I am sure there are other methods.
SS34 how come you don`t use a 33 spring? The curved spring would drop in the pocket better? I made the mistake years ago on first rod and trusted a guy in Gibbon who told me to buy his 36 radius rods and use the 32 spring. It was not until I put the body on that I found out he was totally wrong and wasted money and time. The tire sat wrong in the body. Tire too far forward. Rear fender wouldn`t fit. A 36 spring would also be wrong. Is yours closed drive line or open? If open, are those 40 radius rods and how did you attach at front.? Thanks for the help.
The 33 spring has different mounts on the bells and you would have to change them to use the 33 spring. The 1940 spring just needs some grinding on the sides to fit by the top of the crossmember. It works great and shouldn’t take more then a hour
Right, the basic gear is the same. Only the spline area differs. Changing spring and driveshaft length seems totally unproductive. By the way, the three different banjo rears...modelA-1932, 1932-1934, 1935-48...are all slightly different in length of the banjo and its snout. People used to machine '35-48 Ford gears for use in '32-4 housings, as supply of proper ones and ratio choices were very limited for a while. Now they are routinely reproduced, as it required very little work for the suppliers to make them from the same basic gears as the later ones. I think a lot of what is being said here can be summarized thus: Early Ford suspension is very well engineered and strong, IF its power limits are sufficient for your needs. The torque tube is a key component, and getting equal freedom of movement, control, and geometry with an open rear is not easy and cannot really be done with a simple kit unless you can accept dynamic problems.
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