Vintage Mustang Forums banner

Custom Motor Mount Build

82K views 177 replies 65 participants last post by  Redneckgearhead 
#1 ·
I've always like 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. If I find that the rubber wears too quickly or the bolt pushed through the rubber, I can always buy the urethane shackle bushings to replace these rubber ones. 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. 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! :pirate:
 
See less See more
8
#2 · (Edited)
#3 ·
Yes, well, pretty much anything you can do a Mustang has been "done already". Opentracker pretty much invented roller spring perches. Which diminished not at all the pleasure I got from fabricating my own versions. At some point I may decide to make my own adjustable mounts. I doubt I will duplicate anybody else's efforts exactly but I'm certainly open to ideas.
 
#4 ·
I looked at any aspect that could improve whats already out there, and when you want adjustability in that many directions then the ones that Ron Morris has are about as best you can get design-wise. There may come a point where I get these built and have the motor slid back to the point I need it (to line up the T56 shifter in the stock opening), and completely redesign these so that they are made to be in that location without the adjustments. These will basically be the base point and it's too early to tell which direction I'll go once I get the first set done and installed.

Thanks for the link on the MustangSteve site! Seems Daze and I have similar thoughts on the shackle bushings. I wasn't aware that he thought of this as well.
 
#5 ·
Oops, thought you would have seen that already. Steve has the same issue with the Morris mounts as I do. Those type bushings aren't very good at absorbing vibration. No OEM that I'm aware of (except motorcycles and such) uses such mounts which is probably a telling point. I was thinking of using relocated stock type mounts. Or if I get ambitious, fitting a different type of OEM mount. Way the heck down my to-do list though.
 
#7 ·
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


 
#8 ·
More progress. Got the cardboard cut out and installed. The first iteration I didn't have enough clearance to get a socket onto the nuts of the intermediate plate-to-bushing housing assembly. I moved the bolt location closer to the engine and I now have enough clearance.

Printed out the cut sheet to scale from the AutoCAD 2011 drawings:





I cut out the pieces from the paper cut sheet and traced them onto cardboard. I cut out the cardboard sections and below is what I ended up with. The cardboard is nice thick double ply stuff, so it's not as flimsy





Horrible attempt at the bushing housing, but hey I had to use whatever I had at hand. I used a few layers of paper towel centers with a chunk of wood I cut using a holes saw. It gave me a pretty darn close overall diameter and somewhat located the bolt in the center of the bushing. Hey, its good enough for mockup purposes.









Pictures of the sections all mounted up. Everything fits well, so I'm comfortable enough to start cutting steel. Gotta buy some 3/8" steel for the top plates as well as the DOM tubing for the bearing housing. I hope to start cutting this weekend















One thing not shown in the pics or the CAD file is the top clamp plate that goes on top of the top plate for the two center bolts. It's been added to the CAD and cut sheets this morning. I would have remembered it eventually:lol:
 
#9 ·
Somebody is having a good time, very cool
 
#12 ·
Haven't thought that far ahead to be honest. Let me finish mine to see exactly how long it takes me to cut the steel. When I have everything done and the plans finalized, I'll post a PDF that everyone can print off your own printer and it'll be to scale for a cut sheet.
 
#11 ·
Even in mockup they look pretty cool.
Just a thought, instead of the missing top plate you could just use a pair of carriage bolts in the slots. I've found they cinch down nicely in such applications. Finding some that you are sure of being at least Grade 5 strength might be a little trouble. Maybe McMaster-Carr lists some as graded. Another plus is you could tighten and loosen them with one wrench/socket instead of needing two.
Along the same line, if you go with top plate plan A, it'd be nice if it were milled on each side with the center fitting down into the slot. Overkill thinking maybe, but it would be slick(er).
 
#13 ·
Good thoughts. I don't know how much force those two bolts would see but carriage bolts have a thinner bolt head than a standard bolt but they would make install easier. I really didn't have a problem with the two bolts even when using cardboard. Shaun suggested that I make the shock tower brackets already in the lowered position and use shims/spacers between the engine plate and the intermediate assembly to raise the motor as needed. This may be a pretty good idea for those trying to fine tune their driveline angle.

My next step is to draw up the lowering brackets for the shock towers and then go buy my steel :thumbsup:
 
#14 ·
I think I'm adverse to just bolts through slots from using a lathe and mill, both of which have slots for things to be attached to. Plain bolts are bad because the threads can mar the slots. This can make it difficult to use adjust the proper sliders and T-bolts when you do use them. Whether this should apply at all to your mounts is certainly debatable. There's such a thing as over-engineering things.
OEM's use carriage bolts in situations where strength might an issue. I think the key would be obtaining equivalent bolts to those and I suspect the local hardware store doesn't carry quite what I have in mind. The simplicity of using them is appealing. McMaster-Carr does carry them in grade 5, I looked. Which I am sure would be strong enough for the application, despite the thinner heads.
 
#15 ·
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.




 
#16 ·
For those that are following this build I figured I'd post an update.

Below are some pictures of the raw assembly and then some of them installed. I did run into a slight issue in that with the motor at stock height and using my 1" lowering brackets w/o shims, I only have 1/2" clearance between the block and the top plate. This means that it'll only lower the motor 1/2" instead of the 1" that the brackets are supposed to allow. Somethings definitely screwy here! They were cut correctly (double checked) and measure out correctly in CAD, so I'll have to get out the old motor mount and double check my measured stock mount assembly heights



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.

Another 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.

Tomorrow I hope to sandblast the parts and then get them painted. It might be till Friday before I get to install the mounts to see if these lower the engine enough to get my correct driveline angle. Considering this is my real first fabrication job and very very minimal metal cutting skillz/tools, it's turning out half a$$ decent with exception to the few hiccups. I'll update with more pictures once they are painted and the motor is actually sitting on them




































 
#17 ·
My only suggestions would be, one, be mindful of acceleration/deceleration forces, if these mounts are going to be used in a heavy duty application, like racing. Longitudinal forces can be substantial. Two, be sure to make a transmission mount with similar elastomer to synchronize any natural frequencies of vibration in the mounting system.

On the race car, I used engine plates and a fabricated solid rear crossmember to relocate the engine a couple inches back, but still utilized triangulated tubing struts (imagine one part of a four link) to the chassis off the original engine mount holes in the block to control longitudinal movements.

Good luck. Nice job :)
 
#19 · (Edited)
My only suggestions would be, one, be mindful of acceleration/deceleration forces, if these mounts are going to be used in a heavy duty application, like racing. Longitudinal forces can be substantial. Two, be sure to make a transmission mount with similar elastomer to synchronize any natural frequencies of vibration in the mounting system.

On the race car, I used engine plates and a fabricated solid rear crossmember to relocate the engine a couple inches back, but still utilized triangulated tubing struts (imagine one part of a four link) to the chassis off the original engine mount holes in the block to control longitudinal movements.

Good luck. Nice job :)
just use a spherical bearing turned sideways for the trans mount and the engine aint gonna move forward or backwards and the bearing will allow the rubber in the engine mounts to flex from side to side.:shaking:
 

Attachments

#18 ·
Do you see any weak links in my mounts? This won't be used for racing but I'd like to know any things that you may notice.

I plan on using the stock transmission isolator that utilizes rubber instead of the aftermarket urethane mounts. I'm not sure how the durometer compares between the two rubbers, but it should be somewhat close.
 
#20 ·
How much clearance would you say you have between the t-mount tube OD and the chassis at the closest point?

You should be able to utilize 3/16" - 1/4" material throughout with some load management design. I'd like to see that intermediate bracket capture the tube to spread the load out, especially longitudinal load. If you stay with 3/8" material for the T, you can spot-face the mounting hole and/or use an Allen capscrew instead of a conventional hex bolt.

The important thing to remember is the mounting system is moving in all directions, taking stresses from the unit body, including twisting/shearing loads, and incorporating engine torsional loads. It's not merely an engine mount. If you compare an OEM engine mount to yours, you'll see the differences in how the loads are managed and isolated.

I doubt you'll have any issues with your existing design, but am commenting as if you were planning on producing them to sell. Remember what happens when an OEM engine mount fails. Apply that knowledge to your own design. Plan for it to fail, most likely at a weld point. Manage that failure.

In the pictures below, you can observe how triangulation manages torsional and longitudinal loads, as well as torque reaction. If you look carefully in the first picture, between the McPherson strut and the down-tube triangulator, you will see one of my longitudinal engine control struts. Also, note how the front engine plate (there is a rear one too, not visible) ties the down-tube and the chassis frame rail together, combining with the struts to make the engine an integral structural part of the front chassis. This is all 30 year old technology built by a 19 year old, but the principles are still fairly sound. Not having substantial experience, I tried to anticipate failure paths, both structurally due to my errors, or in a vehicle upset (crash).



 
#21 ·
How much clearance would you say you have between the t-mount tube OD and the chassis at the closest point?

You should be able to utilize 3/16" - 1/4" material throughout with some load management design. I'd like to see that intermediate bracket capture the tube to spread the load out, especially longitudinal load. If you stay with 3/8" material for the T, you can spot-face the mounting hole and/or use an Allen capscrew instead of a conventional hex bolt.

The important thing to remember is the mounting system is moving in all directions, taking stresses from the unit body, including twisting/shearing loads, and incorporating engine torsional loads. It's not merely an engine mount. If you compare an OEM engine mount to yours, you'll see the differences in how the loads are managed and isolated.

I doubt you'll have any issues with your existing design, but am commenting as if you were planning on producing them to sell. Remember what happens when an OEM engine mount fails. Apply that knowledge to your own design. Plan for it to fail, most likely at a weld point. Manage that failure.

In the pictures below, you can observe how triangulation manages torsional and longitudinal loads, as well as torque reaction. If you look carefully in the first picture, between the McPherson strut and the down-tube triangulator, you will see one of my longitudinal engine control struts. Also, note how the front engine plate (there is a rear one too, not visible) ties the down-tube and the chassis frame rail together, combining with the struts to make the engine an integral structural part of the front chassis. This is all 30 year old technology built by a 19 year old, but the principles are still fairly sound. Not having substantial experience, I tried to anticipate failure paths, both structurally due to my errors, or in a vehicle upset (crash).



nice oil cooler !
 
#24 · (Edited)
stock rubber mounts up front with a 7/16" flat head allen bolt through it with a counter sink drilled in the mount so the head is flush and a type c nut on the top. i use toploaders not autos and the tail i use is the c7or with the wide mount pattern and i roadrace so i am not taching up and dumpin the clutch or coming off the line hard for a dead stop. i have known people who ran solid or urathane mounts or a combination on early mustangs and had bad vibration issues etc. the tha sperical trans bearing allows the trans to rotate side to side only as much as the engine mounts will allow. if you brake the left engine mount on a 65-66 the engine will lift up and the oil filter will hit the shock tower cause the trans mount just keeps the trans and engine from moving side to side. jet airplanes use 3 of these sperical bearings to hold the engine to the pylon and 3 to hold the pylon to the wing so that the engine can wiggle a bit so its not stressing the wing spar and causing cracks. the 2 front bearings have there bolt holes facing front to back and the single rear non load bearing bearing has the bolt hole facing sideways. any jet that hangs below a wing uses this mounting system. the front 2 bearings are anywhere from 3/4" to 1.5" and the rear bearing from 3/8" to 15/16". a thrust link with a sperical bearing on each end transfers the foward thrust of the engine to the wing spar but does not support the weight of the engine nor have anything to do with holding the engine on the wing. the thrust link has 1 sperical bearing on each end. if you have ever flown in a jet with wing mounted engines and looked at the engine you can see it wiggle from time to time. i have never tried a sperical bearing for the front engine mounts because the modified rubbers work great and i did the sperical mount in the rear to keep the engine from moving foward under load even an 1/8" cause at one time i was using a fan clutch and had a custom made 5 row copper brass crossflow radiator in the car until i made the decision to go with a thinner aluminum with electric fans.
 

Attachments

#26 ·
Well I forgot to put some closure to this thread. I've made some tweaks to my design but nothing major.

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.















There are some washers missing in the pic that were installed later. FYI
 
#29 ·
I would like to have a copy of the autocad file - im a long way away from needed these mounts but will most likely require them. I am a tool and die maker - will make them too. I think I will require them as I am building a motor that will not be stock and being able to play with the mounts to get the shaker assembly to sit just right will be required.

Thanks in advance

Cheers

Nemstang
 
#34 ·
Thanks! Yeah its more of a labor of love type thing. The same can be said about my T56 conversion. Sure I could have forked over money for a bolt in kit, but what's the fun in that? Being an engineer I wanted the challenge of reverse engineering the RM mounts and being able to do them myself. Plus, I wasn't too keen on the Poly bushings RM uses due to vibration transmission, and I wasn't sure if they indeed were the same size as the rear leaf spring shackle bushings. Building them myself means I know the shackle bushings fit perfectly and are easily resourced :thumbsup:

I'm guessing it probably took me a good weekend to build not including the engineering/drafting portion. If a person took them to a place that had a waterjet, they'd have much less time with only a little bit more $$ into them. I also wanted to re-polish my AutoCAD skills since I use Microstation at work. Including the drafting, I probably have about 30 hours in it. It gave me an idea of what kind of R&D goes into parts like this, except this was a bit easier since I copied someone elses idea :)
 
#36 ·
Definitely! You can also tailor it to your needs by making the included shim sketches in case you have clearance issues.

Something you may encounter is that the oil filter will be very close, if not interfering with the top plate. A grinder may be needed to clearance the top plate so that the oil filter spins on easily.

I haven't put many miles on the engine since installing these due to a bad tire, but plan on firing it back up and putting some miles on it this weekend.
 
Top