Custom Motor Mount build

[buening 63]

I posted this on other forums and figured I'd stick it on here as well. I've always liked the Ron Morris motor mounts and everyone else seems to as well, but I just didn't want to fork out $225 for about $20 in steel and $20 in bushings. I also am not a fan of the urethane bushings used, so my design will utilize stock rubber bushings made for the rear shackles of our cars. The urethane bushings transmit too much vibrations to the body of the car, whereas the rubber will not. If I find that the rubber wears too quickly or the bolt pushes through the rubber, I can always buy the urethane shackle bushings to replace these rubber ones or get rubber with a higher durometer (stiffness). This may get a little wordy, but better to have too much info than not enough.

 

Initially I wanted to mimic the Ron Morris design but I wasn't a fan of the motor mounts being of 3 sections: the top plate, the intermediate section consisting of a top plate/angled plate/bushing housing, and the shock tower brackets. Too many sources of bolt slip or possible failure. I wanted to combine the top plate and bushing housing into one, similar to the TCP mounts but I didn't want to lose the option of sliding the engine back (which is the reason for these mounts). I decided to try to make the top plate have long slotted holes and make the front to back motor adjustments through those two bolts that go into the engine. The oil filter is in the way up front on the drivers side and there is a drain plug in the way on the front passenger side. Because of this, I conceded to try and mimic the Ron Morris mounts. My plan is to first make the motor mounts at the stock height to make sure everything lines up, and after that I will adjust my CAD drawings and will make shock tower plates that have 1/4", 1/2", 3/4", and 1" drop. The drop is needed to get the proper driveline angle for my T56 conversion, because at stock height is has 5° of driveline angle.

 

Here is what I have to take measurements from:

 

 

 

 

 

 

 

 

I used a caliper and plumb bob to take the measurements and below is what I came up with, drawn in Autocad:

 

 

 

 

Using these dimensions, I drew up the shock tower brackets. I used 1/2" edge distance from the edge of bolt hole to edge of plate for 7/16" bolt holes (two for shock tower) and 5/8" edge distance for 1/2" bolt holes. I wanted to keep the cutting easy, so the top edge is flat. Due to the different edge distances from the two different bolt hole sizes, the hole centerlines are not inline as seen below:

 

 

 

 

The above drawing started out with pointed corners, and then I started drawing up circles that would make the rounded edges. Below is the result:

 

 

 

 

I also put in the bushing housing and started to draw up the top plate. Below is next step completed:

 

 

 

 

I established the bolt hole locations for the intermediate plate. The long line going at an angle is 45° from the centerline of the bushing. Its just a reference point so that the angle of the plate welded to the bushing housing doesn't get greater than that angle. The next step was finalizing the intermediate plate as seen below:

 

 

 

 

The final step was to draw in the angled plate that connects the bushing housing to the intermediate top plate.

 

 

 

 

The above view is the completed side view of the motor mount assembly. Next week I plan on drawing up the top view showing the width of the bushing, bushing housing, and details of the top plate and intermediate plate. I'm waiting on my rubber shackle bushings to come in the mail. When finalized, I will break up each part so that they can be transferred to steel plate to be cut (cut plans). I plan on dimensioning everything and posting it on here so that other DIY guys can mimic my mounts...at your own risk of course More to come later!

 

Also, when finished I'll be transferring these drawings onto cardboard for mock-up rather than going straight to cutting steel. Just in case something is off! Hope you see that this really isn't rocket science :tongue_smilie:

[buening 63]

More progress on the drawings. I took a guess at the bearing sleeve length and bearing shoulder thickness. Good enough for cardboard mockup at this point

 

Below is the picture of the end view (as looking from the shock tower towards the side of the engine.

 

 

 

Next is to bring up construction lines to complete the top view

 

 

 

Now its just a matter of bringing all lines up and over from side view as well as end view to create the top view. I decided that I had no need to be able to move the engine forward as allowed with the RM mounts. I chose to end the slotted hole at the factory location, and bring the hole forward 1.5" that would allow me to move the engine back 1.5". A quick measurement of my shifter location with the trans in mock-up shows about an inch is needed, but I went with the extra just in case. Below is the end result with all three views finished. Nothing spectacular about them because there is a ton of lines and I got lazy making the linetypes correct for hidden lines. Next up is creating cut sheets to be transferred to cardboard tomorrow and eventually steel

 

[Cruzzar 22]

I did the same thing that you are doing. One suggestion that I would make is to not cut out the hole for the motor mount bolt in the tower brackets. Wait until you get the other brackets done, installed and engine mounted in the car and then you can postion the motor as low as possible (without interferring with steering linkage, etc.) Then you can transfer punch where the bolt hole should go and then finish cutting the metal to center the radius around this hole. You may or may not find that the hole is any different than stock but lowering the motor can help if your putting a TKO trans in, adjusting for header clearance, running an Edelbrock AipGap manifold as well as lowering the CG for better handeling. Here's a pic of one of mine, its since been power coated.

[buening 63]

So you built your own like the RM mounts to? Did you have a thread on it? Thanks for the tip. I'm installing a T56 and need to drop and move the engine back.

[Greenbay stang 10]

If you decide to go the easy rout and buy the RM mounts, I have a set that I was going to put on Ebay in a week or so.

[Cruzzar 22]

I also looked at the RM mounts and decided that there wasn't anything that I could add to an already great design. I didn't post my results because I felt that I didn't have anything to add to his work. I actually felt funny just copying his design but I have a mill, lathe, tig welder and all the raw materials already in my shop except the bushing which I purchased at a 4 wheel drive shop for about $18.

[buening 63]

Yeah I was a bit hesitant since it looks similar to the RM mounts, but these aren't an exact copy. As shown above, I started with the stock hole dimensions and made it my own. In the end it will appear similar to RM, but not a carbon copy. Must be nice to have access to a mill and lathe! I'll probably be cutting this steel plate with a 10tpi metal blade and jigsaw :(

 

BTW, what thickness of steel did you end up using? I'm thinking about going with 3/8" for all plates. I have 5/16" sitting in front of me but wonder if its a bit thin. But, I guess it is what RM uses for all plates but the motor bracket IIRC.

[Cruzzar 22]

For the 2 motor plates that bolt directly onto the engine block and have the slot for front to back adjustment I used 5/16".

For the 4 tower brackets and the 2 rectangular back up plates that mount on top of the adjuster slot on the motor plates, I use 3/16".

All of the other pieces, I used 1/4".

I believe that these are the same thicknesses that the RM mounts use.

All bolts are grade 8

4-3/8 x 3 1/2 NC

4-3/8 x 1 1/4 NC

2-1/2 x 3 1/2 NC

Here are two pics of the finished project.

If I were to make these again, I would not make the slot in the motor bracket that long. You could probably make it half that length. I should have checked this distance when I mocked up my motor in my '70 but didn't and therefor made it similiar to the length of RM's.

Edited April 12, 2010 by Cruzzar

[buening 63]

Thanks for the info. 5/16" eh? Wow thats some thick stuff.

 

Yeah if you look at my last CAD picture I didn't make the slots as long. I have the end of the slot for the factory position and then elongated it so I could slide the motor back 1.5". You did a nice job on your fab, hopefully mine turns out half as good

[buening 63]

I ended up making two different sets of shock tower brackets. The first set is set up for a full 1" drop, and shims were made if needed to shim up the motor between the top motor plate and the intermediate assembly. The second set was set up for a 1/2" drop and the same shims can be used. I didn't feel comfortable using 1/2" or more worth of shims, but others could if they want to save some fabrication time. They could make the set with the full 1" drop and then shim up as far as they want.

 

I ended up using a metal chop saw for the large sections and a 3" air cutoff saw for the finer work. My father's workplace had some extra steel plates and those two saws, so I did the work there. I will say that even with those tools it was not easy getting nice cuts since the chop saw was a smaller one and many times I had to rotate the piece to cut the other half, resulting in not-so-straight cuts. The most difficult part of this whole job was cutting the slotted holes in that thick of steel with round cutoff discs. I drilled holes at the ends of the slotted holes and used the 3" cutoff to cut between the holes. Lets just say they didn't come out as good as I hoped. I started at 10:30am on Saturday and finished all the cutting and drilling at 4pm. That doesn't include cleanup of the edges and holes with a debur bit on my die grinder.

 

I'm still waiting on the DOM tubing to arrive in the mail. I paid $20 shipped for a 1 foot long section of 1.75" OD x 3/16" wall thickness tubing. Not exactly cheap but nowhere within 60 miles carried tubing for some darn reason, so I bought it off of ebay. Once that gets here I'll be welding everything up and then painting it all up pretty.

 

So with the free 3/8" and 3/16" thick steel plates, I will only have the $20 in tubing and $20 in bushings and bolts I estimate that I had about 1sq ft of 3/8" steel plate and 1.5sq ft of 3/16" steel plate total, which from my local prices came up to about $25 total for both plates. With that, one could make these for around $65 not including your own labor time and tools.

 

Below are some pics but are nothing too exciting since they are bare steel and still need cleaned up. I did check for waterjet pricing in my area and only found two places that have the capability. One wanted $150 and the other wanted $225 for all 18 pieces. My mounts may not look as pretty as one from a waterjet, but paying those prices would not have saved me a dime.

 

These pics are for one motor mount only. The other set looks identical obviously. The lower right and lower left pieces are 3/8" as well as the triangular piece, while the rest is 3/16". The lower right plate probably weighs about 5lbs by itself....definitely bulky! I only had time to make a single 3/16" shim for each side. If more shims are needed I will make them. The shim is to the right of the lower left 3/8" piece and didn't come out exactly like the 3/8" bracket, so I'll take a grinder to get them closer to the same size.

 

I just need to get out the die grinder and get to work cleaning up these edges! Will report back whenever I get the tubing and everything welded and edges all cleaned up.

 

 

 

[buening 63]

I should probably update this thread and give it a good closing, since it's all painted and installed.

 

One of the pictures below shows the stock rubber leaf spring bushings next to the final version. I had to grind down the dome so that it is close to being flat, and then had to cut down the bushing length since the width of the steel tube is narrower than a standard leaf spring. Cutting that thick of rubber and making it look nice is a challenge. Thankfully the ends will be covered inside the tube housing.

 

One mistake that I made was that I forgot to include the weld width in my intermediate/Tplate, so I have very little clearance to the weld for the locknut. I plan on using nylok nuts, but there isn't room for any kind of washer there. I'll be changing the CAD files so that the holes are slightly further apart, so that others won't run into the same issue.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Well I finally got time to take the mounts out of the car and get them painted up. Below are pics of the final assembly. For those that want the CAD file or the PDF to print out for a cut-sheet, send me a PM or reply to the thread and I'll send it to you. A few things I learned from this process is that moving the engine back 1" is about the safe maximum before you get into clearance issues, not only with the motor mounts but other things like heater core tubes or PS lines. I went with 1.25" but it required modifications to the mounts and the previous two items. Also, dropping the motor 1" is the max you can go with these mounts without issues with the bushing housing and the shock towers, as well as steering drag link clearance issues with the oil pan. They are still really close and may find that I have vibration/clattering issues with the motor running. If I have problems I'll report back.

 

 

 

 

 

 

 

[buening 63]

 

 

 

And here they are installed on the car:

 

 

 

 

 

 

[juit 34]

did you ever made this for selling?

[buening 63]

Nah, I don't have the time to make these to sell. These were done by hand and a bit time consuming to make large batches. All shops around my area want an arm and a leg to make them in their laser/water jets.

 

I see I still need to fix the pictures on this thread. Damn picture hosting site crashed and lost all the links!

[juit 34]

nice job

[phlegm 10]

buening may not be interested in selling them.. but I am. At least 3 sets of them.

Custom Motor Mount Plates $75 (including shipping) -- 1969stang.com FS section

 

The only catch is that I don't want to provide the round tubing or the welding. These I had plasma cut at work. I do IT work for a company that builds semi trailers.

 

Its all held together by grade 2 bolts just to show a completed product. This one happens to be using the 1/2" drop brackets.

 

 

Just the plates required to build them.

[RPM 1,190]

Good idea Phlegem. Me thinks you should include the tubing to make it more attractive to sell. Then the only steps the buyer would need to do is the welding, and buy the bushings and bolts. Increase the price if needed. This advice is worth what you paid for it :)

 

Bob

[phlegm 10]

Thought about it, probably should. And maybe I will. But not right now. I figured anybody that had a welder or was having theirs welded by somebody would know where to source that cheaper locally.

 

The problem is that I'm an IT guy, not a fabricator and my shop is a mess, perpetually. Last summer I LOST a total of 3ft of 1.5"OD x 1 3/8" ID that had been cut into 3" long pieces; that had been cut, chamfered (beveled) and was on a wire to hold it all as a loop I had it hanging in the garage. Then, poof, gone. Either my wife or father in law moved it to "where it belongs" and I haven't seen it in a year.

 

For my own build in the attached pictures, I used 1 1/2" OD x 1 3/8" ID CREW (1/16" wall). Probably undersize for what Buening would like to see used, but what I had on hand.

 

Then again I have a 220hp SBF backed with a C4, rubber insulated 2pc driveshaft and an open differential, I doubt the thick/thinness of the bushing housing for the motor mount will ever be a problem.

 

I may order up a couple feet of the DOM buening spec'd in the drawings just in case people would rather not have to search.