8 cylinder front engine iconic vehicle
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By ChrisZ
#85864
So I've been working a good bit with my new 3d printer and it's time to make something useful: On my 86 928S the front bushings that go on the front of the jackscrew closest to the motor assembly are gone and as a result the screw flops around in the metal shaft. Anyone know what the dimensions are for that bushing in terms of inside diameter, outside diameter, length, and length between where it goes from large diameter to smaller?

Worst case I can measure myself and do trial+error to find the right size but it's gotta be somewhere. PET is no help as the seat rails are sold as a complete assembly.

I'll put the dimensions on Thingieverse. First I'll print it in PET plastic to test, then print it in Nylon for strength.
Last edited by ChrisZ on Sun Jun 20, 2021 5:51 am, edited 1 time in total.
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By sh944
#0
I'll ping El Jefe and see if we can get permissions set up to allow print files to be posted somewhere. Do you have a preference on file type? I usually go with .stl when I go to print but we can settle on STEP, OBJ or 3ML if anyone has a strong preference.
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By jschiller
#85873
You might want to peruse this thread at the other place if you haven't already searched out some answers. It may save you some development time.
https://rennlist.com/forums/928-forum/1 ... hread.html

And this one:
https://rennlist.com/forums/928/874290- ... ow-to.html
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By Geza-aka-Zombo
#85950
I don't recall there being a plastic bushing at the front of the power screw on mine. At the front there were plastic coated thrust bearings, where the plastic degraded and broke off. See the attached for what I did for my fix.
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By ChrisZ
#85989
Thanks everyone! I'll take the seat out again this weekend and measure/print up some things. Once I figure it out I'll upload them to Makerbot's Thingverse so other people can just print them out and go.
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By ChrisZ
#86010
Thanks for the links! Helpful but it looks like the 85 and 86 seats are different from the 87>. Here are pics from my car:

Image

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Left side, you can see the spacer is shot

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Right side, spacer still there.

I printed up a test spacer, once I get those seat bolts off I'll try to put it on.
Image
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By Geza-aka-Zombo
#86020
Oh yes, that is definitely different than my '87. Looks like the thrust bearings are separated, one at the front and one at the back of the power screw. Good luck.
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By ChrisZ
#86039
It might be a significantly easier repair: The trick is how to get that bolt off the top barrel so I can remove the thrust bearings, clean them, and put the new spacer in place. I'll work on it tomorrow and see how things go. Best part about the 3d printer is I can whip up a new part in 15 minutes if the current one doesn't fit :-)
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By ChrisZ
#86118
Ok, got the bottom bolt off and started working on that side. These seats have the same spacer on both ends, which does make things a bit easier. And the bottom spacer was undamaged so I got good measurements.

Building a new spacer is a bit tougher than I thought: You have to have a slightly larger than 10mm hole so the shaft can turn, and a slightly smaller rim so the washers and thrust bearing can mate up properly. So after about 6 prints I got the right sizes and everything fits.

Image

Next up I'll try it in the car. Since the front bolt is harder to get off I think I'll try putting the new bushing on the back and put the back one on the front. There is little to no damage on the front bushing; I wonder if it breaks when someone jumps into the seat or something like that. Anyway once I know it fits I'll post the files to thingiverse.

Because you know I don't have to worry about copyright ownership here unlike Rennlist where they would own all of this work......
Bertrand Daoust liked this
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By Don Smith
#86137
Nice job!
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By ChrisZ
#86372
Ok, I now have a perfect one for inside diameter and ride for the thrust washers. Also printed in PETG so it is much stronger and resistant to high temps. The bushing rides inside of it with no slop yet turns with a feather touch.

I installed that one on the back of the jackscrew, now I have the front off. I'm printing the next one with an additional .1mm wider at the seat end of the bushing as the rear one had a tiny bit of movement and perfect should be perfect. So instead of a 12.8mm outer diameter I bumped it up to 13. Will see how it looks, and take some final pics.
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By ChrisZ
#86398
All done!

I took a look at the inside set of spacers, and both of them were pretty badly worn. So I got the wrenches out (there is a 10mm flat spot on the back of the jackscrew, use that to counterpull the 17mm bolts) one at a time. The trick to doing it without removing those allen bolts is to loosen the back one, then move the jackscrew forward, then take the back one off, then start taking the front one off, pull back on the jackscrew, and eventually the front bolt will come off and it will slip off the adjusting cable without having to touch the front cable holders.

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Once off I took pictures of the spacers, as you can see they were.... sad.

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New spacers went on, closed it up, tightened the bolts. No slack, no moving back and forth or side to side on the jackscrews. Hint: The trick to keeping the jackscrews in sync is to never let them turn. Mark the inside of the flat spot on each one, then loosen the bolts. You can move them a bit with the 10mm wrench to help get the 17mm on but as long as you don't turn them 180 degrees and set them back when putting the front cables back in they will stay in sync.

Here's the seat all assembled.
Image

When I put it in the car and hooked it up to power it was a bit tight. So I loosened the back bolts *slightly* and sure enough it's perfect now. It's possible that the spacers are .1mm too thick on the middle part, but they will probably wear, and to be honest I'd rather have a snug fit as opposed to the seat moving. Another option is I noticed there was an extra washer on the front of each jackscrew assembly ahead of the bearing and washer, behind the bolt. That might have been a PO attempt to tighten the loose screws, not sure. If anyone can take their seat apart and check I would appreciate.

So we're done. I'll print another set for the driver's side just because, and will do that another weekend. Then we'll see how long they last, my guess is years since they're not really used a whole lot and I'm guessing the older bushings cracked up due to age.

Never dull.
Hey_Allen liked this
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By worf
#86698
What he wrote —^.

Great job.
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By sh944
#87816
In addition to posting it on Thingi, perhaps we should start a thread here archiving useful Porsche part files. It might make Open Road a better technical resource.
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By ChrisZ
#87824
Not a bad idea, how can we set up a download section for stuff like this?

Next up is a top for the little levers that you use to put the armrests out. I've wanted one of those for awhile now. Hm. Might just get my calipers tonight and start measuring........
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By ChrisZ
#88269
Ok, I just printed a really nice set of little buttons that go over the metal latch on the door armrest levers. Now I can push down on the button gently and use the armrests.

Anyone want one? More to the point, what other kinds of plastic things have we always wanted but Porsche ditched out on production? I wonder if it's possible to print some of those ABS/brake sensor wiring grommets. That would be *really* handy for a lot of people. Hm.

Other suggestions?
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By worf
#88310
ChrisZ wrote: Mon Jun 28, 2021 5:49 pm I wonder if it's possible to print some of those ABS/brake sensor wiring grommets. That would be *really* handy for a lot of people. Hm.
The rubber retainer grommets for the ABS/RDK/BPW wheel well harnesses:
- need to be flexible; not sure if you can 3d-print rubbery stuff? (If you can, we need NLA engine bay hoses...)
- *are* available in a kit for all four corners. Jeannie at 928 Specialists has them.
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By Hey_Allen
#88312
I'm definitely curious as to what you're describing on that last latch cover item.
As to things people print, as least one person was working on reprinting the center blanking plate for the seat switches on early cars.
I'm thinking about printing some replacement covers for the ends of the grab handles on the ceiling, as one or two are missing from my car.

As to printing grommets, I know you can print in TPU of various densities, but I don't know how well it withstands automotive environmental influences (eg: fuel, oil, coolant, heat...)

Not a stock replacement part, but I'll most likely end up printing a light holder for my hatch, since the whole trim panel across the top of the hatch went missing somewhere along the car's life before it came to me. Once I get some decent tint in the rear window, I'm not going to worry so much about rear visors and the top trim, so...
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By hilton
#89509
Nice - what material did you print the seat bushings from? PLA? The crumbled bit I found under one of the seats in my '89 looked like they used to be pliant?

For squishy or oil resistant locations, its possible to print in nylon with some effort (especially on keeping the filament dry). I recall Colin was printing nylon oil separators at one point (may still be?) as part of his crankcase breather/vacuum kit.

And on the topic of the ABS harness grommets - I had the same thought and saved a half a one last time I rebuilt a front harness in my '87.. but looking at them, it'll take some creativity to make two halves which clip together so you can get them onto the harness in the first place, given the barrel connector on the end of the wire prohibits sliding them on?
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By worf
#89524
hilton wrote: Sun Jul 04, 2021 10:43 am … it'll take some creativity to make two halves which clip together so you can get them onto the harness in the first place, given the barrel connector on the end of the wire prohibits sliding them on?
Exactly.
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By ChrisZ
#89807
Not really: For the rubber ones I got I simply slit them open, put them around the wire, then glued them with a drop of CA glue. No problems since. For a plastic version I could do them in 2 parts, then assemble on the bracket and glue it there or something. They cost a *lot* when bought by themselves, and to be honest their main job is to hold the wire in place at key points, not to provide compressive force.

I'll work on it in the next few weeks. Right now I'm just happy with the little buttons on the armrests. It's the simple things in life that mean so much....
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By ChrisZ
#89817
hilton wrote:Nice - what material did you print the seat bushings from? PLA? The crumbled bit I found under one of the seats in my '89 looked like they used to be pliant?
They should be solid. For fitting purposes I printed them with PLA but I don't think it would hold up under use. So I instead printed them in PETG, which does require higher temps to print (not a big problem) but also holds up under stress and higher temps. It's billed as Nylon equal with less smell when printing.

So far they seem to be holding up fine with lithium grease.
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By sh944
#89837
I'll ping El Jefe and see if we can get permissions set up to allow print files to be posted somewhere. Do you have a preference on file type? I usually go with .stl when I go to print but we can settle on STEP, OBJ or 3ML if anyone has a strong preference.
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By Hey_Allen
#90078
sh944 wrote: Tue Jul 06, 2021 4:52 pm Do you have a preference on file type? I usually go with .stl when I go to print but we can settle on STEP, OBJ or 3ML if anyone has a strong preference.
Personally, I look for stl files to print, and step, sldprt, or similar if it's something that might require editing.

As to places to host the files, thingiverse is common if you don't mind the open world seeing the parts.
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By ChrisZ
#90087
STL is probably the best format, people can edit it, and set the parameters for slicing as they see fit.

Meantime here is a picture of the armrest button, it looks really good and fits well.

Image

It's the little things that can make life so much nicer.
Bertrand Daoust liked this
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By checkmate1996
#92555
Kevin from Atlanta was working On this issue. Different seats from different years have different requirements as I found out working with him.. The best solution atleast for the my seats in my 85 euro would be to make a two part “snap-in” solution so you only have to remove the seat and nothing else. What I did is make a spacer with a pie shaped cut out and snapped them in. it’s worked just fine over the last couple of years. Work with roger and he can maybe get these mass produced . This has been a nagging problem that needs to be solved.
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By ChrisZ
#92712
Waiting on a reply from Roger on it, but in the meantime I'd say if you want a set let me know and I'll print them up. They *really* make a difference, and I have to pull the driver's side and switch those out.

It's not too bad to get the bolts off, the biggest pain is removing the seat, and you really want to at least clear out the old grunge and stuff and clean/lubricate those thrust washers. Just make sure to take off the circlips and mark the position of the worm drives so the seat runners don't go too far out of alignment.

So what other little annoying things are there that I can print? Someone mentioned over on the other forum that their spur gear for the climate control sheared teeth, that should be a pretty simple thing to print up.....
checkmate1996 liked this
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By checkmate1996
#92727
Very cool Chris! Thank you!
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By ChrisZ
#101622
Well I have been doing more tweaking and can now print 4 at a time using PETG. I'll print up a bunch for Frenzy, how does $40 for a set of four sound? $20 for a set of two of the armrest lever buttons.

If you want a set let me know and I'll earmark them for you.
Bertrand Daoust liked this
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By worf
#101660
Aren’t the arm rest buttons still available new?

Why didn’t you copy the factory arm rest button’s shape?
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By linderpat
#101739
ChrisZ wrote: Sat Jun 19, 2021 3:03 pm
Once off I took pictures of the spacers, as you can see they were.... sad.

Here's the seat all assembled.
Image
Chris - looking at your seat, I see the same thing that I saw with my driver's seat (MY 85). The rails and bolt holes do not line up with each other. I had removed my seat to repair switches (didn't work by the way; seat still doesn't recline). When I went to put it back in, the one rail was extended a little bit farther than the other rail. I could not push it to align it either. I did not look at it when I removed the seat, so I do not know if they were equal to begin with on both sides, but I know I did nothing to move the seat on the rails when it was out of the car. I had a bitch of a time bolting that last bolt in. I see your rails are just like mine are.
Is that how these are supposed to be?
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By FLInstigator
#101741
Chris I have a FormLabs 3L SLA printer if you want to try printing them with a different technology. I currently have gray and black material to play with. I don't need the buttons or spacers but can definitely print you a few sets to try out.
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By ChrisZ
#102179
worf wrote: Wed Sep 01, 2021 10:26 pm Aren’t the arm rest buttons still available new?

Why didn’t you copy the factory arm rest button’s shape?
Oddly enough I've never seen an arm rest button and when I did a quick Ebay/Google image view I didn't see one. The one I made has the right size slot, feels about right, and has a slight offset so it fills the space, is comfortable to press, and doesn't hit the door card.

How much does a real one go for?
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By ChrisZ
#102180
linderpat wrote: Thu Sep 02, 2021 11:31 am Chris - looking at your seat, I see the same thing that I saw with my driver's seat (MY 85). The rails and bolt holes do not line up with each other. I had removed my seat to repair switches (didn't work by the way; seat still doesn't recline). When I went to put it back in, the one rail was extended a little bit farther than the other rail. I could not push it to align it either. I did not look at it when I removed the seat, so I do not know if they were equal to begin with on both sides, but I know I did nothing to move the seat on the rails when it was out of the car. I had a bitch of a time bolting that last bolt in. I see your rails are just like mine are.
Is that how these are supposed to be?
Really? My holes lined up right on the money, you can take the cables off on the front and turn one or the other to align them if they are off. Also if they were off I would expect a lot of binding in the mechanism when the seat tried to move.

How far off were yours? Maybe a PO did something and threw them out of whack?
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By fpena944
#102646
Just a reminder if anyone does want to share any type of 3d print file that is not copyrighted then head over to the "Parts Mill" forum and they can be uploaded right there. Please start a new topic for each individual file so it can be discussed if needed:

Parts Mill
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By ChrisZ
#102823
Texas993 wrote: Mon Sep 06, 2021 9:51 pm I'd like to buy a set of the seat bushings. How can I contact you? (don't see a direct message function on this forum)
PM is fine, I don't get notifications. I sent you my email address, just drop me a check or bitcoin/litecoin, let me know your address and I'll send out either 1 or two sets.

This is fun, I'm actually building something for people :-)
C
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By ChrisZ
#104142
Did the driver's side this weekend with a set straight off the printer. One was a bit of a snug fit, but I realized the old plastic was smeared on the bolt. Cleaned off bolt and all was well. 3 out of the four original bushings were destroyed, so these are definitely a wear item.

This time instead of lubricating and cleaning everything I just slapped the new bushings in as is and snugged everything up. Only cleaning was the one rear bolt which was coated in old bearing paste, other than that I left all the grime, dirt, and junk under there. I figured it would be interesting to do a worst case torture test on them. The motors are under a bit more load than the passenger side, I'll demonstrate at Frenzy. The trick with using the 10mm wrench to hold the screw while loosening the bolts is great, and as long as you wait till everything is loosened before removing the drive wire the screws will turn together and stay in relative alignment.

I'll pack a couple of sets for sale at Frenzy, if anyone else wants a set PM me and we can do Paypal for now.

C

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