Make a Replacement Intake Tube
01-15-2014, 11:42 PM
#46
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I have some thoughts along those lines, but not quite that one. My first thought about that idea is that if that were an option I think one could just put the later airbox lid on the box. In fact, I think that is what might be the case for someone in this thread who says he has an 86.5 with the later 3 inch openings. I think that the limitation for the 85 and 86 cars is the space along side the intake plenum and that that is what limits the size of the opening in the air box lid.
My thought about making a different air box lid with larger openings than the 2 3/4 inches they now have is to make the opening narrow and tall and then make an air tube that is also narrow and tall at the outlet end to match. I think that might fit the space and still allow a larger air passage.
The limitation is how to make a form for the tubes in that shape since I don't have a CNC wood lathe. I might figure out a way to do it if and when I get to it.
I think my next step in this project, if this current tube idea even works, is to make a replacement for the original tubes and that will be suitable for the GTSs.
My thought about making a different air box lid with larger openings than the 2 3/4 inches they now have is to make the opening narrow and tall and then make an air tube that is also narrow and tall at the outlet end to match. I think that might fit the space and still allow a larger air passage.
The limitation is how to make a form for the tubes in that shape since I don't have a CNC wood lathe. I might figure out a way to do it if and when I get to it.
I think my next step in this project, if this current tube idea even works, is to make a replacement for the original tubes and that will be suitable for the GTSs.
01-16-2014, 08:58 AM
#47
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So I go down to the garage to document the inlet size of my original and replacement air cleaner tops. I’ve got the camera and ruler ready. I’m ready for my moment of glory. I’m going to be right about something on this forum. I photograph the part number. I hold up the ruler, with camera ready, and then what the hell. The inlet diameter is 2.75”. Surely it must be the top of my ’80. Wrong. Both my original and replacement tops have an inlet diameter of ~2.75”. Long story short, don’t listen to me for now. I will be right about something on this forum someday though.
Jerry, if the vacuum form doesn't work what about doing a 2 piece design then gluing them together. From your other posts that I have been lurking on the glue seems to be as strong if not stronger than the plastic you are using. I know this would mean another failure point but I'm thinking it wouldn't be all that bad. This would allow you to use your normal forming methods I believe. Just a backup idea as I'm by no means an expert. Just a lowly guy behind a keyboard
Anywho keep on rocking on Jerry!!!
01-16-2014, 10:41 AM
#48
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There are two basic limitations that I see on the success of this project. One of them I have mentioned before and that is the ability to get the ABS plastic to shrink down around the smallest part of the form when the vacuum is introduced, without wrinkling.
The other concern is if the "accordian" design I am going to put into parts of the tube will allow enough flexibility for the tube to bend from its cold straight shape to the curve and sharp kink it needs to fit the 85-86 cars' tube space. I wont know the answer to either of these possible issues until I have the project complete.
About the glue--Alan and Brad have expressed opposing views about the glue. The ABS glue that one buys at the hardware store is ABS plastic disolved in MEK. MEK dissolves ABS plastic. When the glue is put onto ABS plastic that does not have any wax or oil on it and which may occasionally be sanded lightly to open up its pores, the MEK in the glue starts to disolve it. Then the disolved ABS mixes with the ABS already dissolved in the glue, which fills up any voids, and then the MEK evaporates. The end result is pretty much like a weld. The glue joint will set fairly quickly, but it will not cure for some time. Even after a full day of curing the joint can sometimes be pulled apart with some force. I don't know just how long it takes for all the MEK to dissipate leaving the joint very permanent.
I think I will be forming the hand-made plastic tubes after about a day or more of curing. Then by the time a successful tube is shipped I doubt that the glue joint will ever fail, at least not because of the glue.
The other concern is if the "accordian" design I am going to put into parts of the tube will allow enough flexibility for the tube to bend from its cold straight shape to the curve and sharp kink it needs to fit the 85-86 cars' tube space. I wont know the answer to either of these possible issues until I have the project complete.
About the glue--Alan and Brad have expressed opposing views about the glue. The ABS glue that one buys at the hardware store is ABS plastic disolved in MEK. MEK dissolves ABS plastic. When the glue is put onto ABS plastic that does not have any wax or oil on it and which may occasionally be sanded lightly to open up its pores, the MEK in the glue starts to disolve it. Then the disolved ABS mixes with the ABS already dissolved in the glue, which fills up any voids, and then the MEK evaporates. The end result is pretty much like a weld. The glue joint will set fairly quickly, but it will not cure for some time. Even after a full day of curing the joint can sometimes be pulled apart with some force. I don't know just how long it takes for all the MEK to dissipate leaving the joint very permanent.
I think I will be forming the hand-made plastic tubes after about a day or more of curing. Then by the time a successful tube is shipped I doubt that the glue joint will ever fail, at least not because of the glue.
01-16-2014, 02:24 PM
#49
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Looks like you only need to make one tube with a stamped area on each side to cut a hole for the TB cover breather nozzle - marked on one side L and the other side R.
Just cut the hole for the desired side.
Maybe I'm missing something?
Just cut the hole for the desired side.
Maybe I'm missing something?
01-16-2014, 03:21 PM
#51
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I may need a set of these for my 85 Euro though I can use the bigger diameter tubes as I have a 16V..
Last edited by Mrmerlin; 01-16-2014 at 04:02 PM.
01-16-2014, 03:22 PM
#52
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Yes, Randy, you are missing something. You are missing the end of the first sentence in the second paragaraph of the opening post in this thread where I said ". . . and to do it by designing one tube that will functioin on either side of the engine."
However, what I intend to do is design a tube with a flat on one side of the place where it fits over the outlet from the timing belt cover, and that flat will have a hole in it. I am hoping that my design will end up flexible enough, as mentioned above, to be able to bend left or right to the shape needed on either side of the engine. If so, it will not need to have two holes in it.
However, what I intend to do is design a tube with a flat on one side of the place where it fits over the outlet from the timing belt cover, and that flat will have a hole in it. I am hoping that my design will end up flexible enough, as mentioned above, to be able to bend left or right to the shape needed on either side of the engine. If so, it will not need to have two holes in it.
01-16-2014, 03:49 PM
#53
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Before I came to the office this morning I went out to the shop and checked on the epoxy. It is pretty well set, but is still a little sticky feeling. That's probably because it is so cold out there. I took all the clamps off and then brought all the sticks into the house and set them over one of the heat outlets to see if that will help. In any case I think the glue is set enough for me to finish the milling of all the wood.
At lunch time I went out to HF and bought a set of 25 inch long drill bits with one of them 7/16 inch which I think will work well for the long hole through the center segment of the form. Then, after I get out of here I'm going to change the chuck in my metal lathe to my 4-jaw and use that to set up and drill the long hole. That's after I finish up the milling of the wood, or at least the center segment. But, I'll probably do all the milling first.
I also bought another trim router which I plan to set up with some jigging to be able to mill the bevel on the long edges of the ABS sheets I plan to work with. I like to set these routers up and then leave them set for a specific purpose in order to minimize the set-up time on any given project. Then I just go buy another one for the next project.
I also went to visit with one of my plastics forming experts to consult about the concern of the plastic shrinking to the smaller diameters in the forming process. He hasn't done that kind of forming before but seems confident that it is going to work just the way I am hoping, but maybe only with the massage technique and careful application of vacuum.
At lunch time I went out to HF and bought a set of 25 inch long drill bits with one of them 7/16 inch which I think will work well for the long hole through the center segment of the form. Then, after I get out of here I'm going to change the chuck in my metal lathe to my 4-jaw and use that to set up and drill the long hole. That's after I finish up the milling of the wood, or at least the center segment. But, I'll probably do all the milling first.
I also bought another trim router which I plan to set up with some jigging to be able to mill the bevel on the long edges of the ABS sheets I plan to work with. I like to set these routers up and then leave them set for a specific purpose in order to minimize the set-up time on any given project. Then I just go buy another one for the next project.
I also went to visit with one of my plastics forming experts to consult about the concern of the plastic shrinking to the smaller diameters in the forming process. He hasn't done that kind of forming before but seems confident that it is going to work just the way I am hoping, but maybe only with the massage technique and careful application of vacuum.
Last edited by Jerry Feather; 01-31-2014 at 11:30 AM.
01-16-2014, 04:40 PM
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01-16-2014, 04:41 PM
#55
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01-16-2014, 04:47 PM
#56
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What about an intake tube that is not flexible, but can be attached by standard couplers/reducers on either end?
01-16-2014, 05:05 PM
#57
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Happy to point you in the right direction!
01-16-2014, 06:22 PM
#58
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I milled the sticks that had cured pretty well and now have them into a bundle that will make up the form. I have two hose clamps on them now, but I have not put the wax paper in the bundle yet. The reason for the wax paper is because I kind of intend to finish the form with a coat or two of epoxy after it is turned to final shape and I am pretty sure that without wax paper in between the seperate pieces of the form they will end up stuck together.
The bundle is a little less than exact, but I think with all the hose clamps on it and getting turned to shape the gaps will not show in the final product. Or, if they do it will only be on the inside.
The bundle is a little less than exact, but I think with all the hose clamps on it and getting turned to shape the gaps will not show in the final product. Or, if they do it will only be on the inside.
01-16-2014, 09:14 PM
#59
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Well, that worked pretty well. I did what I said and got a nice 7/16 inch hole drilled all the way through the center segment longways. Now I'm working on fitting a small face plate to one end of the bundle so I can start turning the form.
I have some tooling to build first, and I need to do some measuring in the 85 to be sure of the proper dimensions. The tooling is some kind of mechanism that will allow me to use a trim router with a 3/8 inch round cove bit to make the channels in the accordian sections of the form for the new design. I hope to work something up that will allow me to do these channels very precisely, much moreso than I will be able to do freehand, I think. I have a rough idea of how to make something that I can clamp onto the tool rest on the lathe and then move it one notch at a time and cut with the router.
I have some tooling to build first, and I need to do some measuring in the 85 to be sure of the proper dimensions. The tooling is some kind of mechanism that will allow me to use a trim router with a 3/8 inch round cove bit to make the channels in the accordian sections of the form for the new design. I hope to work something up that will allow me to do these channels very precisely, much moreso than I will be able to do freehand, I think. I have a rough idea of how to make something that I can clamp onto the tool rest on the lathe and then move it one notch at a time and cut with the router.
