TVR Scott (Forum Supporter) said:What's up with that ass-flavored weld bead on picture 3? You promised me better!
Meh, cleaned up, it'll look as good as most factory welds.
TVR Scott (Forum Supporter) said:What's up with that ass-flavored weld bead on picture 3? You promised me better!
Meh, cleaned up, it'll look as good as most factory welds.
In reply to nocones :
Good catch! Yes, crush tubes are part of the plan, but I didn't have them fitted when I took the pix.
In reply to nocones :
fun note: the crush tubes are made from the shift stabilizer rod that was still attached to the trans when I got it.
With engine mounts fully welded, I need to get the powertrain in position fore-aft, side-side, and the inner CVs have to be centered in their available space. To pull this off, I need to revise the R&R cart to have the height adjusters attach to the front mounts. It's an easy mod, just a couple minutes with the death wheel.
so I moved on to pondering trans mount. Adapting the Audi mount to the C5 cradle would crash with the rear bar, so I think I've figured out a good way to mimic the load distribution across existing threaded bosses in the case. The new mount will be above the trans, attached to a bolt-in crossmember as shown in the sketch below:
shouldn't be too bad to make. I'll use old-school sway bar end link bushings at first, though they might be too stiff. Says the guy with solid engine mounts. While I was fiddling around with ideas, I raided the red solo cup of C4 fasteners. That car continues to give.
so here's what I'm aiming to accomplish in the next 2 days. Some of these will take minutes, others will take hours.
But when this list is complete, the powertrain will be fully supported by the car. And I'll probably drink a beer at that.
Here's where we were at the end of the night Thursday:
Yesterday at 5PM I had an eye exam including dilation, so I didn't do anything in the garage last night. 
Before the eye exam, I stopped at an atypical parts house called Hobby Lobby:
this is an RTV silicone product that cures to a 45A hardness, which is kinda squishy. The OE trans mount is also pretty squishy, so I hope this comes out close. Cure time is 8-18 hours. Mama gave me a 40% off coupon, so $18 plus tax instead of $30. Will pro-rate for actual weight used, because Challenge.
This AM i started actually making the trans mounts. Using a chunk of cattle fence gate for the outer shell, I got a reasonably straight death wheel cut by using a hose clamp as a guide:
then cleaned up both faces on the lathe. Used the same technique for the inner sleeve. To clean up the inner surface of the outer shell, I chucked up a wire wheel in the drill press:
and the result passed my stringent QC checks. With inner and outer bits clean, I did the math to figure out how much silicone to mix:
Figured a good bit would stay inside the mixing cup, so used 1.5x the required volume of each ingredient. Measured, mixed, poured, and curing:
Cost per part:
$2.06
i hope this E36 M3 works!
Good luck Patrick. 45 Shore A is pretty soft so watch for tearing
In reply to AngryCorvair (Forum Supporter) :
I love how you did all those calculations to figure out the volume of the trans mount then said berk it I'll wing it and add 50% more cause hell we know that's what NASA did when they sent a man to the moon.
I used 60A from McMaster-Carr and it worked quite well for the 944 transaxle mount.
Hopefully the 45 works, but I know that those transaxles aren't terribly happy with lots of twist from soft bushings.
I'm thinking there won't be a ton of movement since the engine mounts are solid. I'll have one of these home brewed mounts on each side, hanging from above, with bolts horizontal. Primary loading will be about 150 lbs per mount, compression below axis and tension above:
and here's my NASA fudge factor:
which has 0% consequence to the space flight since it is an excess to the manufacturing process, not an excess to the component.
In reply to Stampie (FS) :
Not gonna lie though, the idea of a NASA Rocket Scientist just saying "berkeley it, add 50%" made me smile.
Update: the stiffness of the cured material feels fine, but since it's a mold-making formulation it didn't have sufficient bite on the center sleeve, which twisted right out with very little force. 
In reply to AngryCorvair (Forum Supporter) :
Next iteration- weld some pins on the center that will get encapsulated by the goo?
Pins? Like clip off a bunch of mig wire on it before? Maybe more like hair...
I haven’t look at your inner pin/sleeve but mechanical interlocks like pins would be helpful. Better would be through holes if possible. I also think you need a higher durometer material for this application.
Can you press fit a hockey puck into your steel outer sleeve with a center bore for that inner sleeve?
wawazat said:Can you press fit a hockey puck into your steel outer sleeve with a center bore for that inner sleeve?
Lathe hockey puck to tiny oversize, freeze, put some adhesive on the warm sleeve and push it in, let it expand into place? I got a 12 pack of pucks cheap from Howie's Hockey Tape
Fill the mounts with the cheapest Window Weld knock-off you can find?
In reply to Patrick (Forum Supporter) :
I think a stickier batch of goo is the answer here. This stuff is a mold material, and it seems like it's got mold release built in. I think the durometer would be fine, but I was able to push the cured material out of the shell with my thumbs. It didn't stick at all. 100% of the rubber came out intact.
Give it something to mechanically cling to
Urethane Shore 80 from Reynolds Advanced Materials is what I use. Very grippy/sticky with no mold release built in. Mold Making & Casting Supplies from Reynolds Advanced Materials
It's hot in the garage today, and I'm still dehydrated from yesterday. Thinking about putting it on CL. I mean, I know what I've got, and it's pretty obvious that all the hard work is done.
In reply to AngryCorvair (Forum Supporter) :
Yeah, that is a pretty nice ladder. Good money to be made there.
In reply to TVR Scott (Forum Supporter) :
You must be new to CL. I'm obviously talking about the hand saw.
Since trans mounts are on hold for a couple days, I'm knocking out a few things at the front of the car. Bolted up the pedal assembly so I could install brake master and start plumbing that system.
I can also figure out how to mount the clutch master and modify the pedal for correct travel ratio.
Clutch MC stroke is 1", and pedal swing is 5". So I need to measure the length of the clutch pedal, from center of pivot to center of pad. Divide that by 5, and that's the distance from center of pivot to center of clutch MC pushrod attachment. There's plenty of space behind the dash to hide all this. I like to apply the sleeper philosophy as much as possible. ;-)
but do you want to use the entire stroke on the MC? I think I'd shoot for 3/4 of the stroke or something. Also you need to consider your slave volume and movement distance requirement before you drill that hole. I'm sure you're already planning that
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