We are trying to expand on our line of products and haven't seen this anywhere
They would be built out of .25" 6061-T6 square tubing and .3125" flat bar
Ballpark $500. We already have the jig built for the few steel repros we've made, so this could happen next week if it's found to be a worthwhile endeavor.
Thoughts? This isn't about weight savings. It's for people who need an '88 cradle or a modified cradle. Less weight is just a bonus
I appreciate the comments on the issue of welding with aluminum. I have a BS in Mechanical Engineering from UNLV and have been welding for 30+ years, with all the WABO certs to go along with that experience
Since you have the jig, can you make them up on request? This is prob one of those things that you may only sell a handfull of, so you may not get the number you need to make big money on it, but if you can do them adhoc it may work out. Have any pics of the others you have made? Can you change up the design? Like remove the hump for the exhaust. If you run a 3800 you may not need the exhaust hump.
Since you have the jig, can you make them up on request? This is prob one of those things that you may only sell a handfull of, so you may not get the number you need to make big money on it, but if you can do them adhoc it may work out. Have any pics of the others you have made? Can you change up the design? Like remove the hump for the exhaust. If you run a 3800 you may not need the exhaust hump.
Rob
Edited the above but, yes, it would be no problem to change them as long as we get detailed drawings. The last one we built was some 15 years ago so I might have a couple photos I can scan. I have no problem even just throwing one together just for pics.
Ballpark $500. We already have the jig built for the few steel repros we've made, so this could happen next week if it's found to be a worthwhile endeavor.
How much for the one of the steel reproductions? Any pictures?
If you plan to use 1/4" wall square tubing for the cradle, you will have a difficult time hitting those weight targets. It will take about 11.5' of material to make the basic side rails and crossmemebers (not including the rear uprights to connect to the chassis. My Ryerson book doesn't list 1/4" wall on anything smaller than 3x3, but if you could get some 2 x 2 square with 1/4" wall, it would weigh about 2.1 lbs/ft = 24 lbs. without factoring in the mounting pockets, sleeves, the rear uprights for the attachment to the chassis, and engine pad.
Now if you switched to round tubing, then a 2" OD with 1/4" wall is 1.62 lbs/ft = 18 lbs and much more likely to hit the desired weight target.
We are trying to expand on our line of products and haven't seen this anywhere
They would be built out of .25" 6061-T6 square tubing and .3125" flat bar
Ballpark $500. We already have the jig built for the few steel repros we've made, so this could happen next week if it's found to be a worthwhile endeavor.
Thoughts?
Remember that welding ruins the T6 heat treatment...
Why are you using 6061-T6? As soon as you weld it all the strength related to the heat treament is lost. Unless the design is such that the welded joints are stressed very little (not the stock cradle configuration) you are relying on a soft condition 8000 PSI yeild strength. If you were to utilize an alloy such as 5052 the soft condition yeild stregth is 13000 PSI The alloys in their full hard configuration have similar strengths 5052-H38 is 37000psi and 6061-T6 is 40000. 6061 can be re-aged to gain back strength, 5052 cannot. 5052 is also less flexible at full hardness than 6061. The fatigue strength for 5052 is also higher in all conditions
I am just wondering what made you decide on 6061-T6, since it's strength is derived from age-hardening and heat treatment. Something that is lost during the welding process.
[This message has been edited by FieroWannaBe (edited 09-28-2012).]
I like the idea of making changes to relocate the suspension links, to accommodate a lowered suspension. I also might suggest that you design a cradle to accommodate all the changes necessary to install a Northstar. The most notable being the relocated front crossmember, in order to clear the oil filter.
I'm sure there are other changes that may be desired/necessary. Those are just the two that come to my mind.
Heck... I'm not even sure that aluminum is necessary. Just something useful for us potential swappers who don't have that kind of fabrication experience.
The whole reason for 6061 is cost and availability. The original was already thoroughly tested in Cosmos so I just changed the material to 6061-T6, making adjustments for the weld points of roughly 50% yield strength in the HAZ, which is still lower than T4, but everything should still be AOK
If we find any problems we will simply reheat and quench. Our oven will heat upwards of 1000* so it won't be a problem. We have a couple hundred feet of 2x2x1/4 that I would like to get rid of
You may want to design it to use the '84-87 rear cradle bolts. The shorter '88 bolts are not plentiful.
Just a thought.
------------------ Jonathan 23K mile '85 notchie - Still under construction https://www.fiero.nl/forum/Forum2/HTML/121056.html I'm not a mechanic but I play one in my garage - me Power tends to corrupt, and absolute power corrupts absolutely - Lord Acton Those who hammer their guns into plows will plow for those who do not - Thomas Jefferson The tree of liberty must be refreshed from time to time, with the blood of patriots and tyrants - Thomas Jefferson
It would be cool to have a lower weight cradle, and I agree of the suspension changes would be great, but one problem with aluminum alloys is the bulk modulus is half of steels, or in other wrords how stiff or resistant the material is to deflection. So typically with aluminum to get a similar stiffness you need to have larger tubes than comparible steel which is a bonus as it increases strength. Also as has been mentioned you will change the heat treatment at the weld site, a problem welding any material, also the chemistry of the weld rod is also important. A clever way of creating butt joints would be cool since you would not destroy the heat treatment. Steels have a similar problem willl upset the microstructure (think of it like a heat treatment) as well but with a low carbon steel it is not as much as a problem as it is for the heat treated steels. Again the rod chemistry is important to also understand. I am interested!
[This message has been edited by montage (edited 09-28-2012).]
Seems like 11 kpsi is a good figure for residual strength. You certainly should re-heat treat, but it is a long process - about 10-12 hours at 900 or so, then quench, then another 10 hours at 350 or so if memory serves. Might be interested, would prefer adjusted suspension pickup points, but how would you handle the hump?
I appreciate the comments on the issue of welding with aluminum. I have a BS in Mechanical Engineering from UNLV and have been welding for 30+ years, with all the WABO certs to go along with that experience
I've got it covered
I'll go ahead and have one built this next week and post some pictures
Sounds like you got it covered, have you considered aluminum uprights too? Haha. But you have my interest, I would like to see a completed unit as well.
Sounds like you have peaked our interest in your aluminum cradle idea FriendOfYours. I agree that 6061-T6 is suitable for this application. We used hundreds of thousands of pounds of 6061-T6 every year in our shipyard and its a great alloy to work with. You may consider a few extra gussets strategically placed. I look forward to seeing your final offering.
Hell yeah. We have been needing a modular cradle for years. This would make swaps so much easier. Can you imagine all the extra room we would have around the drivetrain? Plus, its just a matter of adding the correct mounting points for the various drivetrain combinations. The possibilities... WOW Ring ring.. yes, I need a cradle for a 88 running an L67/F40 or 4.9/4T60 or ECOTEC/F23..... Oh my ! I'd be in even if it was just tubular steel, actually, I'd prefer it.
[This message has been edited by BV MotorSports (edited 09-28-2012).]
I dont see enough of a weight savings to justify the cost.
Now, if someone were to make the entire frame out of aluminum...
It isn't about the weight savings. It is about cost and availability. For people that are 84-87 who want to upgrade won't have to find an '88 to tear apart either
Aluminum tube is significantly cheaper than steel right now and we have a surplus at the shop
Like mentioned above, the ability to install an '88 cradle in a pre-88 Fiero without destroying an 88 Fiero in the process may be worth it. Plus, he said he can make custom cradles, if we supply detailed drawings. That, IMO, is pretty freaking cool. I can think of some good uses for that service, already. (Northstar swap, custom suspension geometry, etc)
Like mentioned above, the ability to install an '88 cradle in a pre-88 Fiero without destroying an 88 Fiero in the process may be worth it. Plus, he said he can make custom cradles, if we supply detailed drawings. That, IMO, is pretty freaking cool. I can think of some good uses for that service, already. (Northstar swap, custom suspension geometry, etc)
The only thing that really has to be dealt with as well is the 88 upright, anothe rhard to find part. I think a well designed aluminum replacement piece has it's merits as well.
I would worry about the tabs that the control arms bolt to. I think having a repo steel one is great news. I would have bought one for my LS swap if it had been out and was exact repo of the original in steel.
Aren't the 88 uprights swappable with uprights from another car?
Nope...
There are several from W-body's and some toyotas that are similar in shape/concept, but the axle center-line is much closer to the lateral link pivot bolt... which if anything you want the replacement to have that bolt further away from the axle center-line.
Why stop at the cradle? The biggest project I'll be lucky to get around to is painting the frame. If I don't all the other work will likely be wasted. With CAD/CAM an alloy space frame should not be out of the question.
There are two aluminum space frames in existence. Alcan made 2 back in the late 80s from the steel dies. They used a combination of adhesives in some areas and welded in others. They were supposed to be torsionaly stronger than their steel counterparts and weighed less. Now if we could get our hands on one of them???
Subscribin' to this. I would REALLY like to get info and feedback about this. I got an 88 cradle that has rust damage literally the size of the Grand Canyon.
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