Weekend Project Step notching a 51 Chevy

How wide is the inside of that notch?? Ya the only solution I would say is just lop that sucker off and link it. set your ride height, weld the rear to the frame so it dosent move and lop those babies off. then set up your links. You cant pull that torque tube back by redrilling the perches it wont move back its on a piviot ball. It will move around but wont move back. You were gonna link it anyway right? go for it, Its winter !!

 

Ya I want to link it. The notch is 4 nches wide, jsut like the frame. The winter thing doesnt really apply in So-cal. I will play arround to see if there is ANY amount that I can pull the axle back. But linking it is looking better and better.

Can I just make a link out of some channel? The links would have to have quite a bit of kick up in them.

 

I'd play it safe and cut away the notch as needed. Then probably weld more material to the front of the notch to get back the strength. Moving the drive line could bring some new unexpected problems to solve. I think you always get less surprises modifying something that doesn't move compared to something that does.

 

Sorry, but that notch gives me a bellyache, maybe weld some rebar in the trunk for extra support or at least some fireworks for when that thing snaps under stress.

The best rods are always a combination of engineering design, craftsmanship, creativity and balls. At least you have one of those qualities going for you. There are so many good tech posts on chasis work and so many people willing to share their wisdom here, I hate to see someone take the "ratrod" thing to mean sloppy thinking and sloppy work. It wouldn't matter much to me, but if you lose your rearend at speed, we've all got loved ones on the road behind you.

 

You make a good point. I am going to get back there and measure EVERYTHING again, I think there is plenty of room as it is , if I link it.

 

If it were me, (and I don't know shit) I think I would re-notch the frame, seems you didn't allow for the upward arc of the rear end when you did the placement of the notches.
If you were to move the axle back, it wouldn't center the wheel at ride height, and open a can of works as far as the torque tube goes.

 

once again Blown240,don't trip!!it's all good.just slow down bro.if your gonna link it later,just put a bump stop in it for now,so it don't hit metal to metal.you're already lower than you were before.think of it as only temporary.but....if you have to have it further down,the cheapest thing to do is to cut the pivot brackets off the rear end,re-drill the centering hole,position the pivot point directly underneath the axle,weld it back up. and your good.dont move the rearend back.it looks like your axle is pretty centered in the notch already.once you link it,there wont be anything inside that notch area.pm if you want to rap about it.and you're right......we cruise all year long in South Califas!!!!

 

I'll send you a big bottle of "Pepto Bismol".you're stomach might feel better if you were a little less negative."Have A Nice Day"

 

Thanks for the encouraging words laid55. I am going to unbolt the axle from the blocks and get it where I want it. Then I will figure out the best way to attach it.

Is there any reason that I couldn't just get some regular round u bolts and run them over the axle instead of having these square ones gettin in the way?

 

I got to agree with eroc. but tried to express my dismay in a more positive way. it looks to me like you did not plan this out at all, and now you are in big trouble.

you can not move the rear end back. for too many reasons to go into here. so ignore everything said about that.

if you brought that to me to fix I'd start all over. get some sturdy 2x3 tubing and tie up the front and rear frame halves together and cut out the whole thing. then rebuild the notch much lower, and of course, have the front part as far ahead as possible.

set the frame up level on jackstands. use a plumb bob to go straight up from the spring pivot which is causing your problem... add a bit for the slight arc that the rear travels due to being anchored at the front u-joint.

either build your notch as a box without the overlap, or better yet use square tubing instead, that is not the strongest way to weld a box tube together.

measure everything 3 times... think of all posssible clearance problems you may encounter through the whole range of travel your suspension will have.

and jeeze loueeze... do it with a 220 welder.

 

Is there any reason that I couldn't just get some regular round u bolts and run them over the axle instead of having these square ones gettin in the way?

the axle needs to pivot since it is a torque tube, if you bolted the axle to the spring solid it would bind. evntually something would break.

 

once again!!!he ain't asking for advise on how to do it over!!Help the dude out!!


Blown240.49ratfink is right in that you can't put u-bolts over the axle.it has to move freely on that pivot point.

one thing I would "suggest":run one piece of flat stock on the bottom of the front half of the frame,up into the step-notch,and onto the rear section of the frame.to tie it all together.at least 3/8" thick.

 

Same is true if a four link is installed. The rearend pivots at the transmission at the universal yoke at the transmission. If you built your four links long enough that they would pivot in the same place (inline with the universal yoke), you would be fine. The shorter your four links get, the more shear stress is going try to rip the links apart. The reason that the stock system works is because the axle is allowed to pivot on that horizontal bolt that passes through the tabs on the rear end.

You have mentioned that you want to four link it many times. Unless you plan on converting it to an open driveline or create a mount on the axle that allows the rearend to pivot independent of the four links (which I don't recommend), I would forget that idea.

If that were my car and I didn't want to convert to an open driveline, I would redo the notch so that the rearend can freely move and I would consider creating a wishbone type arrangment similar to the the early Fords where the wishbones are attached to the rear axle out toward where the leaf springs attach now. They would extend from those two points as far forward as possible and attach to the actual torque tube. Then I would add as long of a panhard rod as possible to control the side to side motion. If the wishbones were positioned and shaped correctly, I think that you could install them so that very little if any interference would occur with the floor or frame.

Picture unceremoniously stolen from an ad by 8thdaycr8.

 

ok I went and got some pics of exactly what I am up against. It acutall isnt all that bad....

The axle is exactly where it should be and its staying there. I am not going to try to move it. And I would not 4 link it, it would be a 2 link. That should work, as I have seen it done before on these cars.

Anyway, Here are some pics of exactly what hitting:



another angle:



Really all I need to do is figure out the best way to leave the axle where it is, and move the blocks back, under the axle or 2 link it. That would solve all the problems and the car would lay out.

As far as redoing the notch, that isnt an option, I know I can get this one to work. But the idea of a 3/8 plate on the inside is a good one...


Heres a fun little pic of the wway the previous owner ran some brake lines....

 

Sorry, I guess I read that wrong. Same issues apply as far as length and pivot points though. The closer you can get your front pivot points to the universal yoke, the more you lessen the stresses on the link mounts and the yoke itself.

 

Cool, good to know.

 

Blown240, sorry if i came on a bit strong with my comment. Good luck with the project, i do want to see how it turns out and what the stance looks like when you've got it dialed in.

 

Thanks. Dont worry about it, everybody is entitled to their opinion.

 

Sorry about the post hi-jack, but what bags are recommended for this application? How much travel can be expected? We are planning on bagging my son's 52 in the next couple of months. It looks like to get the rockers on the ground with the bags deflated, the ride height with bags completely filled still seems pretty low. I would assume the ride quality might not be the greatest with the bags inflated enough to get the height.

 

once again!!!he ain't asking for advise on how to do it over!!Help the dude out!!..

I've come to this post 5 times to help him out. he's getting all sorts of shitty advice, move the rear end??? WTF are you guys thinking

And I would not 4 link it, it would be a 2 link. That should work, as I have seen it done before on these cars

just cause you've seen it done does not mean it works. a two link with a torque tube would be like a 4 link with an open rear... except one set of links is welded solid to the rear end and they are 6(?) feet long.. while the others are 3 feet long or so.

all your ideas about modifying the part that is hitting is a big bunch of work. then not only is your notch poorly welded, but now so are the brackets that hold the rear end to the spring

 

so your saying that if you move those perches directly under the axle,and run two links from the stock front leaf hangers,that won't work? I hope that's not what your saying.
to run links from the from the front of the torque tube pivot point is ridiculous.this aint a baja racer it's a lowrider.how much travel do you think you need?and why are you guys so sure that the welds are going to be shitty and not hold up.I personally know of a few cars that have had all their suspension work done with a 110 welder that have thousands of miles on them without a single problem.mine included!

 

you are absolutely right. a 2 link with a torque tube is a great idea. the two conflicting arcs from the two pivot points spaced 3 feet apart will not cause any binding at all.

the person building this car is an obvious craftsman with the tools and knowledge to get the job done right the first time. I mistakenly thought he came here for advice or opinions when actually it was a tech thread showing the rest of us how to do it.

the weld pac welder is a great tool, otherwise home depot and sears would not sell them. 110 volt welders are so good you don't even need to clean the metal, I can't for the life of me understand why people would spend more than the bare minmum when that one will work just fine. you don't even need experience. just plug and go.

 

now that's what I like to see.someone with a sense of humor.Take note everyone.I told you "Fink"was good for something

 

Ok, hear me out. I know alot of people have been throwing a lot of ideas your way, but let me throw something out here. If you don't like what I have to say, then you have every right to to tell me to piss off. First of all, maybe I'm wrong, but it looks like you are doing bags with the leaf springs. I would NOT recommend this. It causes way to much stress on the leafs and they will eventually break. I would strongly suggest doing a 2-link. You're already under there and have the car torn apart, why do it again?

I helped my friend (happy hoppy here on the board) redo his rear air bag setup. It had been done by someone else and the execution and workmanship was not great. It was not designed right. The axle would come up and hit the shock, not allowing the car to go all the way down, one of the notches was further forward than the other, etc, etc. We made some mounts on the inside of the framerail and used 2-link bars that were about 40" long which helped make a nice gentle arc and didn't pull the axle too far forward. We used Firestone sleeve bags on top of the axle which give plenty of lift and a very nice ride. We made the panhard bar as long as possible and set it up so that it was parallel to the ground at ride height. He's been driving with setup for over a year and hasn't had any problems. If you want any pics, let me know. Good luck!

 

I've been following this thread with great interest! Here's how Evil1 did his 2 link rear and I'm thinking about doing mine the same way.

 

That works, but with those short trailing arms I bet he gets a lot of arc as the axle moves up and down. The longer the trailing arms the better.

 

It isn't so much about having mega travel as it about having the rear axle (which is solidly attached to the transmission via the torque tube) able to move freely without binding.

If the "2 links" pivot at exactly the same spot as the torque tube (at the transmission yoke) and are solidly mounted under the rear axle (no pivot), the rear axle is free to move in any direction with zero restrictions. In this scenerio you would have run a panhard bar (or equivelant) to control the side to side motion.

Now if all you did was to move the links out away from the transmission but kept them the same length, still pivoting in line with the transmission yoke and solidly mounted to the axle, the rear axle would be free to move up and down (with both wheels moving up and together as in going over a speed bump) completely free of any binding. If one wheel moves up or down, there will be some binding introduced but probably not enough to cause any damage if use with rubber bushings. A panhard bar (or equivelant) should still be used for sidways control although it will has a slightly less critical role in this scenerio.

Now lets say you shorten the links so that they mount at the front leaf spring brackets and they are still solidly mounted to the axle. When the rear axle raises, the short links are trying to move the axle forward (in a fairly tight arc) at a MUCH quicker rate than the torque tube. This in turn is trying to drive the torque tube forward into the transmission causing a bind.

The longer a pivot point is away from an object, the larger its arc. As the arc become shorter or smaller (however you visualize it), the more the object moves forward toward the vertical centerline of the pivot. When you have two different link lengths as you would get when you combine two short links with one long link (torque tube), the two different lengths will fight with each other as the they both want the object (the rear axle in this case) to move in THEIR arc, not the other guys arc. This is what creates the bind.

 

Take a look at this picture:



The axle is still mounted to it's original, rubber bushed pivot and the front of the link has a large rubber bushing. The two rubber bushings will absorb some of the bind that can occur with this type of set-up. With limited travel, this set-up probably works out just fine as it has very close to the same engineering principals as the original leaf spring set-up. Although not ideal, it's not dangerous either.

The big difference in case is leaving the original pivot on the rear axle and running that big bushing at the front of the link.

Blown240, I hate to say this, but I really think you should redo at least the front portion of your notches to make things right. Trying to get away with reengineering the rear axle mount is just not a very efficeint way to go about fixing the problem. Lil' John Buttera said it himself, "Don't be afraid to scrap something and do it over." (or something like that). It will always turn out better the second time.

 

I am pretty much leaning towards doing a 2 link. I would really like to see pics ofthe mounts you built and the panhard bar. Heck any pics would be great. Thanks for your imput.

This is sort of what I would do. I still plan to use a large rubber bushing. Either the original, or perhaps one from a newer car. Volvo 240's have a rear upper arm that usses large rubber bushings on both ends. I was thinking of designing something like that. But I also like the idea of a really long arm.

I dont want to use the leaves. Its amazing how far they have to flex to get this low. I am sure one would break eventually.

 

It would look something like this. With a large rubber bushing at both ends: