My Custom Motor Mount build thread

[Shaun]

Looking good.

Have you put any thought into up and down adjustments? If you built them as low as possible, you could use spacer plates between the motor bracket and the bushing bracket for height adjustment...

 

[65fast]

That looks really good Jeremy! I am glad they worked out good so far. Are you making these with a 1" drop or standard height?

Can't wait to see the finished product.

 

[buening]

Looking good.

Have you put any thought into up and down adjustments? If you built them as low as possible, you could use spacer plates between the motor bracket and the bushing bracket for height adjustment...

Thanks! I will be detailing different shock tower brackets that will each lower the motor 1/4" at a time. I'm shooting for only 1/2"-3/4" drop in order to get the proper driveline angle. While your idea would work, you are essentially making the moment arm larger by using spacers and that location is IMO the weakest spot of the mount. I could be wrong though. The reason my triangular piece is so short is because I was trying to minimize the height of the intermediate "T" section, which also minimizes the distance from the motor to the bushing bolt.

 

[buening]

That looks really good Jeremy! I am glad they worked out good so far. Are you making these with a 1" drop or standard height?

Can't wait to see the finished product.

Thanks! and thanks for the help As stated above I'll be doing multiple shock tower brackets not only for me to use but to give other's their own option if they choose to build their own.

 

[Shaun]

Thanks! I will be detailing different shock tower brackets that will each lower the motor 1/4" at a time. I'm shooting for only 1/2"-3/4" drop in order to get the proper driveline angle. While your idea would work, you are essentially making the moment arm larger by using spacers and that location is IMO the weakest spot of the mount. I could be wrong though. The reason my triangular piece is so short is because I was trying to minimize the height of the intermediate "T" section, which also minimizes the distance from the motor to the bushing bolt.

I don't think a few 1/4" laser/water cut plates that mimic this piece would cause an issue once the clamping force of the bolt is applied:

 

[buening]

I'll look into it Shaun. I'm a structural engineer, so I can run some calcs to actually see how much spacers affect it.

 

[Shaun]

I'll look into it Shaun. I'm a structural engineer, so I can run some calcs to actually see how much spacers affect it.

Just a thought... Then you could move the motor in 3 axis if needed.

 

[buening]

Well Shaun I took your advice. 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 plan on taking pictures this evening, so have patience

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 bj

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 :5 I estimate that I had about 1sq ft of 3/8" steel plate and 1sq 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.

 

[70_Fastback]

I'm anxious to see the pictures.

 

[buening]

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. 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", 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.

 

[B67FSTB]

The way you did this took a lot of work !!!!! Respect!

I don't give any remarks on a job like this because of the hard work you put into this but if I may :

Those two plate in the lower left of the pics , I would make them longer so they support/reach more towards the engine
There is room for this .IMO

 

[buening]

The way you did this took a lot of work !!!!! Respect!

I don't give any remarks on a job like this because of the hard work you put into this but if I may :

Those two plate in the lower left of the pics , I would make them longer so they support/reach more towards the engine
There is room for this .IMO

Thanks for the compliments! There is room for it and for those worried about it can definitely do this when they build their own. You have a somewhat fixed connection at the motor-to-top plate and a reaction/force from the bushing bolt that is a few inches away, so you create torsion (or moment/couple) at these plates. The part of this plate that is towards the engine/oilpan is actually not as critical as the part that is away from the engine, as this part is what sees more bearing pressure or bending force. For ease of mind one could definitely make that pad larger though, but you have to be careful not to make it to big to interfere with the engine bolts on the top plate when slid all the way back. Keep in mind these plates are 3/8" (THICK!) and definitely won't be bending.

 

[apollard]

Keep in mind these plates are 3/8" (THICK!) and definitely won't be bending.

I'm no metallurgist, but that is not necessarily true. I had a trailer axle made (old one rusted away under the coating, luckily I caught it before the wheel decided to go it's own way). They used 1/2 steel where the spindles attach, with 1/4 inch reinforcements. The offset from axle tube to spindle is about an inch, so no huge leverage going there.

Within a few months, they had bent (including the triangular reinforcements) such that the wheels had ~3 degrees of negative camber.

That was when I learned even thick steel bends if it is the wrong grade. The code welders here at the plant recommend chrome moly grades for any structural members, as the common 'mild' steel grades will bend over time. I had one of them redo it with chrome moly. He used 3/8 chrome moly with no reinforcement, and it's still straight as an arrow over 5 years later.

BTW, that is some nice work you've done - lots of effort on that.

 

[buening]

Common steel grade is A36 (36ksi tensile strength) but you can get the 50ksi higher strength stuff. AFAIK chrome moly is typically used in tubing and HSS stock and isn't prevalent in plates, at least in my field of building and bridge design. I believe the steel I used was A36 and Gr50 steel would only be overkill and would add expense to the project. We aren't talking about an extremely high load or a very large offset between supports/load points, so the stress in the steel is pretty small.

With only two bolts holding the 3/8" plates to the motor, you will rip the bolts out of the block before anything happens to these plates. Bending of these plates between the bushing housing and the motor, as I calculated it, is in the magnitude of 0.001" per 1000lbs roughly. Keep in mind there is a rubber bushing supporting this entire thing, so the bolt will shear right through the bushing before anything bends even a slight amount

Also keep in mind the factory mounts used fairly thin steel, which IIRC is about 1/8" stuff throughout.

 

[apollard]

True - the bushing should give before the steel does. My app above has no give (except the steel). We get chrome moly plates here for support of heavy loads on small footprints (load cells, etc). About the same per pound as tubing they tell me.

 

[buening]

Thought I'd post an update. Been crazy busy with everything else in life but had a little time this evening to work on the mounts. I got the intermediate assembly all welded up, but I still need to dress the welds before taking pics. I hope to have that all done tomorrow evening.

I did run into a snag and am not too happy. For some reason the long slotted bolts in the upper plate were drilled to 1/2" and I had planned on using 3/8" bolts. While it'd be easy to say just drill out the intermediate plates for 1/2" bolts, I made the mistake of not giving enough clearance between the center vertical plate and the 3/8" nuts just barely work with the welds as it is. Cutting new top plates would probably be the correct thing to do, but I don't have any steel handy and it'll be another month before I get back to my father's shop (which has the steel fab tools). Any suggestions that would allow me to use what I have? I'm wondering if there couldn't be some kind of bushing/sleeve that could slide on the bolt to take up the slack? It'd be a 1/2" diameter tube with 1/16" wall thickness, and have no clue where or what would work. Hell it may not even be a big deal (overreacting) but it has a sloppy feel to it and would hate for the motor to move around cause of ill-fitting holes, wobbling out the holes or damaging the bolts. I'd hope the bolt clamping force would prevent that though. Let me know what you think!

 

[68EFIvert]

I would go to a local hardware store and see what they can come up with. Recently I had a similar situation and ended up using fuel line as a bushing. I wonder if 3/8" brake line could work for you? Not sure if the 3/8" is ID or OD.

 

[B67FSTB]

If you are sure you don't need to make more mods on the upper plate ,, look for someone who has a lasercutting or waterjetmachine and let it cut out of the material you need.
I don't think it will be that expensive and later on you can distribute the files along the stangfix members who will be glad to contribute in the expence you made and maybe earne some money for your labor.
Beside all this , it will give you a boost.IMO

 

[buening]

Well I got to sleep on it and came to the conclusion that it really shouldn't be a big deal. There are slotted holes in the shock tower brackets to allow side-to-side adjustment and the bolt clamping force is limited because there are bushings between the shock tower brackets......so movement would likely occur there before it ever happens at this top bracket. I'm gonna roll with it for now, and if it starts to bug me I'll make new plates at a later date. Not going to allow this to delay my progress at the moment.

 

[stangg]

Nice Job! If you are at all concerned with the 1/2" slot with the 3/8 bolts, you might want to consider grade 8 flange bolts to help better distribute the clamping force.