I'm putting a '69 bronco 9" in a '37 ford pickup that I'm building for my kids first ride. I'll be using a ladder bar set-up from so cal, a 2 1/2" lower transverse spring with 2"lower shackles. Up front I plan on a stock straight axle, 2" dropped spring with 2" drop shackles, and wishbones split about 8". With the offset of a few inches to the side that the early bronco 9" has, what would be the proper pinion angle be for the rear? I'm planning on dropping a small block and a turbo 350 to make it easy and inexpensive, if that matters. I'm not crunched for time at this point as it looks like I'll be trying to get this f*#king perch free from the axle for the next several months! If anyone is in the Sacramento area that might have a few minutes to look at what I have and what the plan is would be great! I'd like to send my kid off in a ride that drives decent.
I don't see where the offset has anything to do with angle. Find the angle your motor/trans is at (or will be) and do same for the rear..........................
BR is right, the offset has nothing to do with the pinion angle. Put the rear end yoke up 3 degrees and the trans tailshaft down 3 degrees and call it good. Don
As long as the engine/trans is parallel to the chassis center line, when viewed from above, and the whole axle is centered in, and square to the chassis center line, when viewed from above, pinion offset, so long as the driveshaft is not ridiculously short, is irrevalent. The transmission output shaft line and the pinion shaft line need to be parallel, viewed from above, and viewed from the side. -3º/+3º, from the side, as has been mentioned above, is a good setup.
it isn't rocket surgery ---make sure you set it at ride height---you will be able to tune it in with your ladder bars...
I'll have to respectfully disagree. The U-joint working angle is what's important, and any horizontal pinion offset has to be included in the total. This is called a compound angle. The normal maximum working angle for a single cardan U-joint is 3 degrees (for about 5500 rpm), so, for example, if the pinion is offset 1 degree from the engine/trans center line, the vertical pinion up/trans down angles should be about 2 degrees max. See pages #5 and #9 in the link below for more detailed info on this. Most vehicles with offset pinions also have the engine/trans offset the same amount, so the vertical angles are the only ones that need attention. The actual pinion offset on a 9" is about 15/16", so with a centered housing, the U-joint angle is about 1 degree or less for a normal drive shaft length, with a centered engine/trans. Where am I going wrong? http://www2.dana.com/pdf/J3311-1-DSSP.pdf
All u-joints have a minimum and a maximum recommended working angle. Most manufacturers do not recommend exceeding a 7 degree maximum angle... Your mileage may vary...
Working angle, as long is it is not extreme enough to cause other issues, is the primary factor in u-joint life span. The greater the working angles, the shorter the life span. Unless the OP is planning on building this as a extreme daily-driver, or with a super short wheelbase, or both, he should be just fine, as long as parallelism is maintained. U-joints are cheap.
I was wondering about this as well. Mine is offset to the right side. I will be running a really short driveshaft (like 18-20"). I have my angles set at 3*. Is this going to be an issue with my set up?
I wouldn't start over because of it, just might get 70,000 miles out of the U joints instead of 100,000. An offset pinion can be a godsend too, if you somehow end up with 0 deg. on each end after getting things parralell on both ends. Another way of getting some working angle into it.
If one has the option, what is the best height to set the front radius rod pivots, even with the front u-joint?
That is more of a factor of the function of the suspension than the driveshaft. As long as the driveshaft is within safe, sound operational parameters, rear suspension geometry should be considered separately. If you choose your suspension geometry to via accommodating the driveshaft, it may be far from ideal, in terms of CG, roll center, instant center, etc., and handling could be compromised, or at-least, funky.
Oh yeah, forgot about that...thanks. Putting in a T5 at the same time and was just staring at the output shaft and the pinion yoke, the 16" of space between them and what's going to happen to the U-joints. I need to go back and read up on roll center, etc. as I did a month ago before I started...
The angles will be enough to make a noticeable decrease in their overall lifespan. Sounds bad, right? It is not, really. If you had to replace them every 30,000 miles, would that be so bad? Grease them often.
I questioned the guys at Currie over this issue. I have a 9" Bronco housing under a Trifive and they foresaw no problems . Their only concern was eccessive lowering and driveshaft tunnel interference , something I don't have. I would trust their judgement .
30K, ha, takes me 5 years to do that in my daily, which I am intending this to replace btw. So yeah, I could live with that. I have to fab a new trans cross member for the T5 so I have some up and down freedom for output shaft angle. My plan is to also mount the radius rods to the cross member, so those also could go up or down a few inches. And the radius rods aren't mounted to the diff yet so the pinion angle/radius rod relationship isn't set yet either. I'm new to this so just trying to decide which component to set first and hopefully the rest will make sense.
Sweet! My daily is getting replaced with a '60 Falcon, in the works now. I think that you will find that the radius rods, when best set up, will be close to level, observed at the lower tube.
I went through this same thing on my model a and we even discussed it here a little bit. I wanted to not run a traditional 3 degree setup because I didnt like the "nose up" angle that my hemi had at 3 degrees. Being that my pinion is offset I mounted everything at 1 degree down/up and relyed on the compound angles provided by the offset pinion to give me the correct u joint lubrication
AD, are you saying 3 degrees is the traditional angle of the engine/trans from horizontal? Or from the frame rails or floor boards? Gimpy, basically for neutral handling I want a horizontal line from rear axle to radius rod front pivots, that sound right? Edit: OK, found a thread on engine angle. still reading. http://www.jalopyjournal.com/forum/showthread.php?t=740465&highlight=engine+angle
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