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Plastic EA-EJ adapter plate?


Uberoo
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So I am thinking about reducing the weight of my project 78' brat as much as I can.While the EJ22 and the 5spd dr both weigh more than the original 1.6 and 4 speed single range they are needed or wanted(depending on your point of view).On the engine side of things Ive replaced steel brackets with aluminum brackets if they exist, while also drilling holes in things to lighten it up(that gram adds up,...eventually).So I did all that stuff but I keep coming back to the 1/2" steel adapter plate.What started as a 20x20 1/2" plate only has a little bit of steel at the edges. So something like 90% of its original mass is gone,even still its big and heavy. I started looking into aluminum plates, but aluminum is expensive and from a cost analysis spending 100-200+ for an aluminum plate that would save maybe 1/2 lb is kinda hard to justify.I could rework my steel plate so there is absolutely no metal where it doesn't touch the engine or transmission, and drill a bunch of holes in the plate to reduce weight even further.Seeing as the plate is just sand witched between to chunks of aluminum, the aluminum will compress long before the steel compresses,and the bolts/nuts will strip out LONG BEFORE either of that happens, so drilling a bunch of holes in it wouldn't affect its compressive strength one bit.So I was thinking,(bad idea I know) if the plate is loaded in a purely compressive state why can't some form of plastic work?Obviously the plate can't be drilled and tapped and expected to hold up,but siamezed bolts that thread into the engine and bolt to the transmission could be used. In my mind the only issues are: the plastic becoming soft and compressing under operating temps, or it would be asking the bolts to provide clamping force as well as prevent rotation of the engine/transmission.So if a plastic was used based on its working temp it should hold up to the pressure without deforming a significant amount.The rotation issue is almost on a non issue because the bolts as they come from the factory are essentially set up the same way.Sure there are a couple of little dowels that help with that to an extent,but ive seen several adapter plates without any holes for the dowels work just fine.Same with stock engines/transmissions that for whatever reason didn't have the dowel pins in.

 

However this all based on my limited knowledge(almost non-existant) of the plastics, but I know that if you put a plastic sheet on concrete and put a lot of weight on it,it wont compress a noticeable amount.Looking online tells me that plastic would be 8x lighter than steel,and 2.7x lighter than aluminum so if it could work that is a significant weight saving for not alot of money.

 

I don't know anything about the plastics other than maybe their abbreviation and what that means.. UHMW,HDPE,PVC,ABS,etc..But maybe someone who works with plastics might be able to shed some light on why this wont work or something suitable that might work?

Edited by Uberoo
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sounds reasonable.

get something auto fluids resistant.

 

to extend your question - can it simply be a series of spacers for each bolt hole that are independent of one another?  rather than a complete one piece plate?

granted there's no surface area to take the loading, the bolts would have to do it all and you'd have to cover the gap to seal it. sounds risky...

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I think I will try it anyway. HDPE is really cheap and a 24x24x1/2 sheet/plate would run me all of $24. In addition to that HDPE is used for body lifts in trucks and some suspension lifts in subarus, so if it can hold 4000lbs without failing or deforming then it can hold whatever force the 4 bolts on the engine can hold. With steel sleeves around the bolts and down pins it should hold up great. HDPE softening temp is about 250-260*F so if the engine gets that hot I will have bigger fish to fry.While the plastic might soften under the the sustained temps with the inserts it shouldn't matter. At the very least if it doesn't work I wont be out much money and will have an excellent jig for making it in metal. If it works then I would have shaved 15 lbs off the front of the car.Roughly guessing the adapter plate has 3 sides 20" long by 2" wide x.5" thick so roughly 60 in^3.steel weighs 17 lbs for that,aluminum weighs 6 lbs,and the plastic weighs 2lbs..

 

So I will put spacers in the lower bolt holes in the transmission so everything is tight and can't rotate and I guess I will see how it works out...

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HDPE will deform when warm......so I don't know about that.

 

And also the whole point of the dowel pins, and the one piece, hard steel or aluminum adapter plate......is to take the rotational load. You need the pins to locate and lock.....and you need the face of the plate to transfer the rotational force to the clamped faces.....

 

........This would be espescially important in a situation with plastic that you would not be able to torque it hard enough to transfer that force to the faces of the plate, engine, and trans.   ALL of the rotational force would now be on the dowel pins.......and they would be in plastic.   And once they start to move, the force transfers to the bolts......which have 1/2 of unsupported shaft sticking through the pastic plate......how much can half an inch of 10mm steel flex????  You'll find out.

 

My guess is that it will work fine for the most part for some amount of time.....maybe to the first clutch change time....... 

 

I will speculate that after some use.......upon disassembly you will find the dowel pins, and the edge along one side dug in by the edge of trans/eng, the bolt holes slightly ovaled to the side the engine torques and slightly bent bolts and one HAMMMERED pilot bearing.....(not to mention the input shaft in the trans)

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Lets also not forget that on a car the  wheel LUGS take the full weight of the car as well as the rotational force.Especially with wheels that have very large center bores.I would wager that the forces on the wheel while turning,accelerating,braking, or running over bumps is far more than the rotational force the bellhousing experiences especially with good motor/transmission mounts.Those lugs are close to the center of the wheel so the force exerted on them has to be pretty high to control the wheel.The bellhousing bolts are much further out so they arn't stressed as much. However, there still is the issue of 1/2" of bolt being unsupported.I'll try it an see, if after everything is connected and tight if I can rotate the engine relative to the transmission(with a prybar) then I will abandon it.With the steel sleeves in the plate I will be able to torque it down as tight as normal.

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As a matter of fact I do.I'll PM you because I am interested in seeing what your friend has to say.Even better if he could whip something up on the printer.Not only would I have a plastic adapter, but I would have a 3d printed adapter! :wub:

 

EDIT: clean out your inbox txakura.The software wont let me message you.

Edited by Uberoo
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Lets also not forget that on a car the  wheel LUGS take the full weight of the car as well as the rotational force.Especially with wheels that have very large center bores.I would wager that the forces on the wheel while turning,accelerating,braking, or running over bumps is far more than the rotational force the bellhousing experiences especially with good motor/transmission mounts.Those lugs are close to the center of the wheel so the force exerted on them has to be pretty high to control the wheel.The bellhousing bolts are much further out so they arn't stressed as much. However, there still is the issue of 1/2" of bolt being unsupported.I'll try it an see, if after everything is connected and tight if I can rotate the engine relative to the transmission(with a prybar) then I will abandon it.With the steel sleeves in the plate I will be able to torque it down as tight as normal.

 

The lugs hold the wheel tight.....it's the vertical faces of the wheel and the hub being squeezed that takes the force.  the lugs just keep them tight.

 

If you were to put a half inch of washers/spacers on each lug....then bolt the wheel on so the faces don't touch.........the wheel would not stay true, and could wobble loose or even break a stud.........And wheels don't get hot like engine does.

 

The problems will really become evident when the engine is hot.......espescially on a hot day.....under hood temps can exceed 200 degrees.

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I once assembled a 2 post "Rotary" brand lift, and it came with a bunch of nylon blocks to level it with. I was thinking, "youve got to be kidding me", figuring that nylon was in no way going to be able to bear all that potential weight. Well guess what, it works just fine, and is impervious to petroleum products.

 

If reducing weight were that important to me, i would totally do it and not give it any more time worrying about it.

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Max temperature for HDPE is 180*F:

http://www.mcmaster.com/#hdpe/=tvp66t

 

You might find something better at McMaster-Carr for material.

Multipurpose Garolite(G-10) is expensive but has the tensile strength & impact resistance you'd want.

Glass-filled plastics have the impact resistance but you have to machine them with carbide tools, adding to the expense.

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As a matter of fact I do.I'll PM you because I am interested in seeing what your friend has to say.Even better if he could whip something up on the printer.Not only would I have a plastic adapter, but I would have a 3d printed adapter! :wub:

 

EDIT: clean out your inbox txakura.The software wont let me message you.

Oops. Yeah.

 

Hey, this is more expensive but... how many adapters could be made of one sheet?

 

http://www.usplastic.com/catalog/item.aspx?itemid=34424&catid=679

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  • 2 weeks later...

Lets also not forget that on a car the  wheel LUGS take the full weight of the car as well as the rotational force.Especially with wheels that have very large center bores.I would wager that the forces on the wheel while turning,accelerating,braking, or running over bumps is far more than the rotational force the bellhousing experiences especially with good motor/transmission mounts.Those lugs are close to the center of the wheel so the force exerted on them has to be pretty high to control the wheel.The bellhousing bolts are much further out so they arn't stressed as much. However, there still is the issue of 1/2" of bolt being unsupported.I'll try it an see, if after everything is connected and tight if I can rotate the engine relative to the transmission(with a prybar) then I will abandon it.With the steel sleeves in the plate I will be able to torque it down as tight as normal.

 

Yep, you're right. That's a fantastic example.

 

 

 

Now, make some plastic 1/2" wheel spacers that are in no way hub-centric, and tell us how those work. And those probably wouldn't have the same heat to deal with (yes, brakes generate heat. But you have to be going pretty hard to exert temperatures for an extended period of time into the hubs like the engine bellhousing experiences).

 

Refer to GLoyale's post. The studs are the clamping force, that clamping force makes it possible for the surfaces to transfer energy via friction. Bellhousing is the same.

 

 

 

I completely believe Scott's number of 7 lbs. That's so very little. You could loose that somewhere else soooo easily. Lightweight battery. Plastic/lexan windows. Bumpers. Sound deadening. Dash. I mean, if you really are building a no-compromise race car.....

 

 

Then you mention cost. Yes, plastic is cheap. But if that thing deforms almost at all. It's going to very quickly put some weird loads on the pilot bearing and input bearing of the transmission, even the main bearings of the engine. What's that going to do to your budget? How about if it gets so deformed to the point that it begins twisting the bolts in their mounting holes. Remember, lug studs are going into steel. While I agree that the bolts won't break, they are threaded into/through aluminum. It's not out of the realm of possibility that they would break out of the bellhousing on one side of the other.

 

 

No way would I do it. I just don't have the time to source and replace an engine block or transmission case just because I tried to shave 5 lbs and $100......No way.

 

 

But, the more I think about it, the more I can picture a broken transmission housing, with a mangled plastic adapter plate, with 4 bolts sticking through it, still with a little chunk of aluminum bolted around each one hanging off the back of your engine. 

 

Something like this one:

566987d1293408550-4-3-coming-soon-700r4-case.jpg

 

 

So....bring a camera!

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Thank you Numbchux. This is not smart. It'll be cheaper in the long run to buy a aluminum adapter plate.

 

But if you serious about this plastic, I will gladly give you my PVC printed adapter plate, I made a while back. Just need to glue each piece together. Lol. Make sure you take a lot of photos after words, I would love to see the after math!

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