Hey guys. I'm planning to put a front and rear driveshaft loop in my Model A frame. Could use a dimension recomendation for the opening width of the loops. Here's what I know so far... - should be within' 6-inches of front u-joint - constructed of 7/8"x.0625 min. tubing or 1/4"x2" min. flat bar Was figuing I would put an oval shape loop in the rear with an inside height dimension of about 9-inches and about 10 inches from the rear u-joint so I can still get the damn shaft in/out and the loop up front would be round or close to round. Any thoughts on these dimensions? I'm going to be right there with the driveshaft since things will be tight. If something comes loose, would be nice to not my right side beat up or my floor destroyed from a whipping driveshaft. Thanks guys! Scooter
That doesn't sound too crazy to me. I just measured my driveshaft hoop on my 37 and it's about the size you quoted (rear). I don't have a hoop at the front. Stu
I made mine out of 3x3/8 flat bar, about 3 3/4 wide inside. Do you think it will have enough clearance, most driveshafts are 3" diameter, I believe.
I have a NOS Harwood loop kit that I just measured for ya. The loop is 5 1/4 inches across inside and is adjustable top to bottom either 9, 8 or 7 inches. These were made to go at the front, I think, so you need to take your suspension travel into account in the rear, but you knew that already.
By the way, the Harwood bolts together so you can remove the bottom of the loop to get the shaft out, if necessary.
WHEWEEE! That's pretty tight brotha! That only gives your frame 3/8" on either side to twist or the suspension to move. Be careful! If all that's tight you might be able to squeek by. Another concern might if the u-joint gives for some reason, depending on how it breaks, if the drive shaft wants to go tangentially horizontal, you may destroy the yoke on your axle and maybe even damage the carrier bearing related to that yoke if it doesn't have a place to go. Just thinking out loud though. May not be a big deal.
This is in the rear, the tabs in the upper right(near the yellow jackstand) are for the 18" long trailing arms, which mount with poly bushings and 9/16" grade 8 bolts. Maybe I should section the loop by cutting vertically through both curved parts and putting in a couple inches of flat bar, making a rectangle shaped loop, with 4 round corners(confusing?) I'd have to cut my crossmember again, and I've finish welded the loop since the photos, too. I was hoping to keep the driveshaft from tearing stuff up inside the car (there will be a 16 ga tunnel)if the u-joint let go.
Hopefully someone will chime in with an answer for you. Don't start cutting just yet. Maybe it's not a big deal. I'm trully not the pro in this area. Someone is though and I'm sure if they see this thread they will tell you. For now, I think I will shoot for 7-1/2" ro 8" wide opening based on the Harwood kit mentioned.
Will do. I only made mine this wide because the "round metal"(O.K. it's schedule 80, or Extra Extra Heavy(yes, that really is an industry term)pipe) I had was this size.
Mine's about the same as the Harwood one shown here. Saved my *** one night, when the trans case broke into three pieces, while going over the finish line at 127 MPH. Sounded like the end of the world happening, an inch from my right leg! At the moment, my focus was on slowing down, while driving through ****** fluid (I thought I'd blown a slick and then broken the wheel). When I looked under there and saw what happened, I ran back and shook the hand of the tech guy that had given me a hard time just hours before. You'll never hear me complain about safety ules...
Exactly the pipe I have made my last two loops from. First one we didnt even cut the pipe, it only had 1/2inch clearance right round the driveshaft it was cloes to the front of the driveshaft and the hotrod had very "tight" rear suspension ie very little up/down travel.The second one had a bit more up/down clearance as per the pic in this thread. The best way to check driveshaft loop clearance would be to raise the car on the ch***is and let the rear suspension hang this will allow you to get the clearance for the bottom half of the loop. Then pull your shocks and springs out and push the diff up on to the bumpstops(as so the car has completly bottomed out on the suspension) this will give you the clearance for the top half of the loop. Take out any panhard or watts links that control side to side movement and push the inside of one wheel against the fender well or ch***is then vise versa to the other side, this will give the sideways clearance should a panhard or watts link break it will not destroy your driveshaft against the loop at the same time. Oh and if you are one of those "street rodders" a drivesahft to an IRS needs hardly any clearances as there is no up down or sideways movement in the diff center.
just thought that id add that the importance of a front hoop isnt in my mind so important to not beat up the floor but to keep you from pole-vaulting your car. which, seems to me would ****
My ch***is has both front,and rear loops.Rear loop opening is 8 1/2 " x 11"with a suspension travel of 3" vertically.
or, there's the easy way out, Richard... run a smaller diameter driveshaft. I mean, what is that car gonna weigh fully loaded and wet? (full of fluids) 2200 pounds? how wide are your rear tires? and what are you running for motor? is an extra 1/4 inch of driveshaft gonna make that big of a difference? for an example- I recently worked on a merc with NO driveshaft clearance...it hit everything it could. vortec 350, heavy car. (kustom) looked at the driveshaft- it was a 3 1/2 inch shaft! we replaced it with a 2 3/4 inch driveshaft. it then broke the not-so sound welds loose at the axle perches! turned the pinion ange up till it finally hit the floor. but it didn't break the driveshaft. and I suspect he has alot more tire than you will.
Holy crimeny Batman! What are you containing with that thing, a gas turbine impeller? Well, no one's going to ask you "where's the beef."
Car will weigh less than 2000, with 10" slicks. I plan to shorten an existing driveshaft, or combine two different makes, as I will run a Chevy 350 trans. and an 8.8 Ford rear. Do you know of any 2.75" shafts that I should be looking out for?
I'm going to resurrect this thread because I'm wondering if there are any other methods to determine the clearance. The more pics the better.
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