I want to take a tube axle and cut it down and pivot it on the front corner of the frame with coil overs and 4/bar and a rack and pinion steering. Think it can work?
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I want to take a tube axle and cut it down and pivot it on the front corner of the frame with coil overs and 4/bar and a rack and pinion steering. Think it can work?
No.
Don
One of the "biggies", Fat Man, tried marketing that design a few years ago with a resounding thud. By shortening the length of each axle the camber issue only increases. It also move the roll center and not for the better. Think of the rear end of an early VW and that's what you have with that design. Now, if you were to take the Ford Twin 'I' Beam design, that can be made to work reasonably well.
It's too bad that it doesn't work well as it is interesting looking
The only way to avoid the extreme camber changes is to extend the swing arm as long as possible to attach to the opposite frame rail as used in the Ford twin I-beam or to lower the pivot point below the axle centreline as used in later (early 70's) Mercedes Benz. Shortening the axle and attaching to the near-side frame rail will result in a raised roll centre, extreme camber change and possible 'tuck-under.' Also remember the early Corvair.
there is going to be 3" of up travel and 2" of down travel. This is being determined by the length of travel allowed with my schocks. Do you still think I have a problem? Thank you for everyones input.
Travel isn't the problem, it's the short axle segments. I guess I prefer something that's been a proven design like this TCI IFS rather then a design that's been a problem shown belowQuote:
Originally Posted by modelb
Sorry it wont load so double click on the link
http://i70.photobucket.com/albums/i8...d/DSC_0028.jpg
Might want to do some studying on all the geometry that goes into the design of a suspension system... There's a lot goes into a good system.
Travel has little to do with it, other then any problems with the geometry will only be magified by more travel. Can't think of any good reasons to have 5" of suspension travel on the front unless you're building an off road 4X4 rig....
For understanding IFS, this is the best book to read. Trust me, I have been through most of them and they left me wondering how to do it. Carroll Smith was the crew chief for Ford Motor Company when they went to LeMans in '65 and whipped the Ferraris. Understanding his explanations is key to building an IFS that works....
http://www.carrollsmith.com/books/tune2win.html
Didn't Leonard Lopez of Dominator Street Rods build a twin beam front suspension similar to the Ford twin 'I' beam? It was called the Dominator Front End and used to be in the Flaming River ads in the monthly magazines but I couldn't find it on their web site. Maybe the reason it wasn't there is because of lack of sales, might have looked good on a show car that never gets driven but didn't work very well on a daily driver. :confused:Quote:
Originally Posted by IC2
Mike
The Twin I Beam setup doesn't work all that well either! Ever seen one backing up? the wheels lean in on top like they are gonna fall over. If you back up and hit the brakes hard they'll hardly get going ahead again. If the shocks get a bit weak they will "jack" the front end one way or the other on big bumps, sometimes 2 feet before you catch it. I much prefer the older trucks with a single I beam under them.
Sidney Allard used the same setup in the '50's on his race cars, and he put the inboard pivots as low as possible. That way all the camber change is the same way, in more on top, and more predictable. Still didn't work though, even with a monster sway bar forcing the wheels to move more or less together. Just not a good setup for handling.
It might work if your frame was 8 feet wide.....
Old Ford frames are too narrow, making the links too short as
everyone said above. Even on the twin I beam setup, the links
are too short.
And dont forget that the Ford pickups with twin I beams usually
ate shocks and tires.
mike in tucson
I have had Ford pickups since 1970 and probably 50,000 yearly---In 1974 had to change drag link at 7,000 miles---- in 2007 had to do ball joints on my 1999 with 350,000 miles- no problems with shocks or tires--however I have seen many on the road that needed some attention and most were probably owner induced or un/underqual repaired at some cheapass tire store
I believe the twin I beam is one of the best suspension systems on the planet, especially for lite/medium trucks---but believe that the move from k-pins to ball joints was a step off a cliff.
Quote:
Originally Posted by jerry clayton
Just be thankful it isn't a Dodge with their front end problems. That makes a set of MOOG greasable ball joints cheap:LOL::LOL:. A friend just bought a low mileage D2500 and is now paying the "price" tho he does love that Cummins engine
When I first got my 70 Ford pick up a couple years ago, in about two weeks I could see it was eating the front tires up. I took it to a place that had a machine to bend the axle's if they needed it. They told me that the bushings were bad and the wheel bearings need replaced and wanted to charge me to the tune of over 2 grand to do this work. I knew the whole front end was brand new but thought the axles may need a bend adjustment, which was not the case at all. I took it to another shop that said the front tire were pointing at each other. They aligned the truck and my front tires still look like new after two years. And the other shop was going to try to stick it to me on a new front end, Oh and I did complain about it to to the manger which probably did no good.
Plus I got charged $80 bucks for the to tell me a bunch of lies.
Kurt
Thanks Gentlemen for destroying my "apparently" dumb and unworkable idea on splitting a tube axle. As someone said, if you do not see it done somewhere it probably did not work. Really guys I appreciate the input, saved me a lot of work for nothing.
The aftermarket did indeed try it, but inevitably it failed.
here is an idea you may be able to use http://www.hotrodders.com/forum/jour...ge=5&reverse=1
I did mock up a split axle using wood. The camber change with 3" of wheel travel was in my opinion, unacceptable.
I met Bret the owner of Fatman at a Goodguys show and discussed it with him. He said it worked fine on his '34 Ford but he severely limited wheel travel. He did not push the product
Just because he built it doesn't make it a good idea, we've all seen examples of bad engineering.Quote:
Originally Posted by Matt167
Mike
The camber change doesn't relate to wheel travel, but to the level of the pivot point--on the ford twin I beam its the opposite frame rail
nothing wrong with that setup. just modified 1981 F-150 to fit the frame. the pivot points were measured out and are the same as what was originally on the F-150. if you look at all his work, you'll note that he doesn't produce shoddy workQuote:
Originally Posted by Mike52
hey guys check out tri c enginering, they are doing the split axle project on one of their cars right now, check it out. just google their name.
dont get too bummed about ideas, it woud be neat, but they would have to be very long or else the tires would tip in and out like crazy. Im not shure how it would handle if you hit a hard bump on one side my thoughts would me it would be pretty jumpy.
Modelb, don't despair. I've ridden in a bucket with the Fat Man split axle and it worked fine. I'm going to split mine next winter. But anchor the axles at the middle, not the frame ends, to minimize the camber change.
Attachment 48803
have you ever had it want to bump steer or go where it wants to during rough roads or chuck holes? How much Travel do you have in the shocks. I have been told to minimize the amount of travel of the shock. But how much is reasonable and still get some ride out of the car?
Most Hot Rod type coilovers have 3" of travel. Correct spring rates and shock valving have a lot more to do with ride and handling quality then the amount of travel the system has...
What kind of car are you going to put this system on? What works on a T Bucket would not be the correct setup for a longer wheelbase heavier car.
It wasn't my car, so can't comment much other than it seemed to be OK and the owner was happy. My bucket has frame-mount R&P, with minor bump steer and I expect even less with the split axle. I don't run shocks now, but plan to use QA1 adjustables to fine tune ride. And you need a steering damper with R&P, or it'll twist your wrists. I'll be posting my work on tbucketeers and maybe here too.
the car is a 1929 model A roadster pick-up with no bed. the wheelbase will be around 103". It has an olds quad4 with a c4 and quick change rear-end. It also has a track style nose. it has 4 wheel coil-overs that are adjustable for ride comfort. this is a hot rod and I do not expect it to ride like my 1952 chevy.
You'll truly minimize the camber impact if you pivot them on the opposing frame rails vs the middle.Quote:
Originally Posted by Potvinguy
Should work out ok on a nice light car like that if you get the geometry correct. Will you be running coilovers? Selecting the right spring rates and shocks becomes even more critical with a lighter car, not much room for error to make the suspension (any style) work correctly and handle good!Quote:
Originally Posted by modelb
I've played with the old Ford Twin I Beam front ends some. They can be made to handle respectably when set up correctly, biggest problem with them from the factory is too much travel and too big of changes in geometry as the suspension moves up and down....
yes I am using coilovers. I am going to weigh the car on each corner with some race car scales a friend has to determine correct springs. As I said before everybodies help is much appreciated. How much do you think the axle should travel from up from ride height. What do you considre the correct settings for caster camber and toe-in? Thanks again.
For a light car, the standard 3" travel coilovers will be fine. Caster should be in the 5 to 7 degrees range, toe in 1/16". Camber is the booger with the twin beams, going to change with the wheel travel..I'd just go for zero with the car at full weight. Easy enough to correct just by changing your coilover height....
