carmudgeons.com - View Single Post - What the Mazda RX-8 should have been (new autocross car build)

John V · 09-23-2018, 06:54 PM

I got my engine brackets made. It took me pretty much all day Saturday to get them cut and tacked in place. It was a lot more difficult than I thought it would be. I think the first issue was that I made them out of much thicker steel than I probably should have. I bought 3/16" steel which is pretty hard to work with, especially since I don't have a professional tubing notcher. I could have made them out of square tubing but round is stronger for this application and well... it looks better.

Anyway, I started with a piece of 1.5" OD steel tubing and made a riser off of the engine mount on the subframe. I welded a bottom piece to it that I cut out of a flat plate of 3/16" steel. I drilled a hole in the bottom for the engine mount stud.

Then I notched another piece of tube to mate up with that vertical tube. This was tricky since the bracket on the engine is about three inches forward of the engine mount, and about an inch and a half up. I ended up having to tweak the notches I put in the tube quite a bit to get the angle right. Then I had to cut the other end of that tube so that it would line up with the engine plate. I cut an oblong hole in each plate for the tube to slide into so it could be welded from both sides.

Anyway... lots of words. Here is what I ended up with on the driver's side (passenger's side was too hard to get a picture of).

Ugly tack welds but my machine really struggles with 3/16" steel. On the other side I pre-heated the brackets with a torch which helped a lot and gave me stronger, smaller tacks.

I took the brackets to my buddy Larry who is an expert TIG welder and he finish welded everything. I was pleased that the gaps were all tight enough for him to TIG, and that the tacks I made had good penetration.

This week I'll clean these up and paint them so they don't rust, but I'm really happy to get this step done. The engine has been supported by a above-engine support bar and it's in the way of getting a lot of stuff done. Tack welding these with that bar in place was a bear. I ended up doing what I could from the bottom with the car on the lift, but access wasn't great under there either and I'm such a novice welder I'm nervous doing anything not on a bench.

Next up... transmission mounts and ... a turbo!

09-23-2018, 06:54 PM	#92
John V No more BMWs Join Date: Apr 2005 Carmudgeonly Ride: Ram, MS3, CX-5, RX-8 Location: Glenwood, MD Posts: 14,753	I got my engine brackets made. It took me pretty much all day Saturday to get them cut and tacked in place. It was a lot more difficult than I thought it would be. I think the first issue was that I made them out of much thicker steel than I probably should have. I bought 3/16" steel which is pretty hard to work with, especially since I don't have a professional tubing notcher. I could have made them out of square tubing but round is stronger for this application and well... it looks better. Anyway, I started with a piece of 1.5" OD steel tubing and made a riser off of the engine mount on the subframe. I welded a bottom piece to it that I cut out of a flat plate of 3/16" steel. I drilled a hole in the bottom for the engine mount stud. Then I notched another piece of tube to mate up with that vertical tube. This was tricky since the bracket on the engine is about three inches forward of the engine mount, and about an inch and a half up. I ended up having to tweak the notches I put in the tube quite a bit to get the angle right. Then I had to cut the other end of that tube so that it would line up with the engine plate. I cut an oblong hole in each plate for the tube to slide into so it could be welded from both sides. Anyway... lots of words. Here is what I ended up with on the driver's side (passenger's side was too hard to get a picture of). Ugly tack welds but my machine really struggles with 3/16" steel. On the other side I pre-heated the brackets with a torch which helped a lot and gave me stronger, smaller tacks. I took the brackets to my buddy Larry who is an expert TIG welder and he finish welded everything. I was pleased that the gaps were all tight enough for him to TIG, and that the tacks I made had good penetration. This week I'll clean these up and paint them so they don't rust, but I'm really happy to get this step done. The engine has been supported by a above-engine support bar and it's in the way of getting a lot of stuff done. Tack welding these with that bar in place was a bear. I ended up doing what I could from the bottom with the car on the lift, but access wasn't great under there either and I'm such a novice welder I'm nervous doing anything not on a bench. Next up... transmission mounts and ... a turbo!