[PAK65]

With the clutch pedal fully to the floor it is still scraping. I did install an ACT flywheel and clutch, and they warn that disengagement is very close to the floor. I have made all of their suggested adjustments, still scrapes.

My next though is that my adapter spacing is not quite right. In order to get full engagement I am thinking I need to move the flywheel closer to the throwout bearing so that it engages sooner when I step on the pedal. Does that sound correct? I think just a couple millimeters will make the difference.

 

[electro wrks]

Pictures of your disassembled complete motor, adapter plate, coupling, clutch, transmission, etc. set-up, would help us figure out your problem. Otherwise, it's wild guessing time.

 

[PAK65]

Well you were right. I did need to take it apart. I don't think it was the clutch still engaged. When I got down to the hub I noticed that it was firmly against the spacer. This is not how I installed it

I also noticed aluminum filings in the spacer ring and when I moved the hub it was obvious that the clutch pressure was pushing the hub back into the aluminum spacer, grinding it off

I searched and found a recommendation to put a small spacer ring that will contact the hub and the rear motor bearing, to prevent the clutch pressure from pushing the hub back. Sounds like a good idea to me. What other approaches do people use to avoid this hub slipping? I was worried when I put it together that the set screw would not be able to keep the hub from moving.

 

[electro wrks]

From experience I suspect we are just seeing the tip of the iceberg of problems here. Again, lotsa photos of the complete set-up would really be useful for us to help you. If we are just shown in drips and drabs the latest problem de jour it can be an incredible waste of time for everybody. Don't feel self conscious about this process. If you don't have a lot of experience setting up these parts, it can be a difficult job to do it right. That's why we here, and it will make our task a lot easier if we can see the big picture (many pictures!).

 

[PAK65]

OK, here we go.
This is the motor in the car. The position is perfect, placing the power train frame 2.6 inches above the frame rails.

Here is the piston for the clutch slave cylinder. I think it is to far out when it engages, although I do get 3/4 inch movement when the clutch pedal is full depressed.

I can push the fork back at least 1/2 inch before it contacts the piston in its resting position. While on the car the piston is engaged though, due to the pressure in the system.

Here is the bell housing, fork, and throwout bearing. Looks OK to me.

You can see where the bearing has made contact. In the miata it is apparently supposed to contact all the time. Also looks alright to me.

Other side, a few marks that were not there, not sure about this:

Looks ok here I think:

continued in next post, 10 picture limit.

 

[PAK65]

Inside surface and flywheel seem alright:

Extension of the hub was very close to where I measured that it should be:

Here is where I think the problem was. The hub is in contact with the aluminum spacer. Not how it was installed. I had 0.03 inch clearance.

And here is where it seems to have been grinding. I didn't take a picture of it, but there were aluminum filings present when I disassembled:

Here is the motor shaft. The key slot is a bit disfigured from the previous install, not this one. The new key is a good tight fit and I believe still makes enough contact:

key in hub:

The set screw seems to have bitten nicely into the key, I don't think it slipped much if at all

When the motor was turning with the car in gear or neutral everything was fine. Stepping on the clutch caused a grind that I though was the clutch failing to fully disengage, but now I think it was the pressure from the clutch pushing the hub back into the spacer ring. If that is true I am thinking the solution would be a spacer that contacts the hub and the rear motor bearing.
Other thoughts appreciated.

 

[electro wrks]

Some preliminaries: Did you measure the distance in the ICE set-up between the machined backside of the block and the flywheel mounting surface on the crankshaft? This is the distance required for the clutch to work properly.

Also, are you using dowels to line up the transmission and adapter plate? The bolts alone usually are not sufficient to properly line things up.

 

[electro wrks]

Also, is the motor shaft threaded inside so it could take a bolt to help hold on the coupling (I think you call it the hub)? Since in your case the pilot bearing is mounted in the flywheel, there may be space for a bolt and heavy duty washer if a step is machined in the flywheel side of the coupling. Unfortunately, the set screw over key design alone sometimes does not hold very well-as you've found out.

 

[PAK65]

Yes, the measurement from the block to the flywheel mount in the original and the spacer and adapter plate puts my coupling at the same distance from the new adapter (0.527) or at least it did before it slipped back.

I have the dowels, but the adapter does not have anywhere for them to go. However, there are two holes in the bellhousing that are threaded and the holes in the adapter plate are tight, so I think that lines it up properly, I did not have any significant vibration (at least at 12 volts).

I think that the bolt and washer would keep it from slipping out, but I don't think that will be a problem, it got pushed in.

I am liking the idea of spacers between the coupler and the motor rear bearing. I need to hold the coupler out 0.26 from the bearing. I found these maching bushings https://www.fastenal.com/products/details/33456 that are the correct inner and outer diameter to go around the shaft and to the diameter of the bearing. They are 10 gauge, which is supposed to be 0.1345 thick, so 2 of those would give me 0.269.

 

[electro wrks]

I have the dowels, but the adapter does not have anywhere for them to go. However, there are two holes in the bellhousing that are threaded and the holes in the adapter plate are tight, so I think that lines it up properly, I did not have any significant vibration (at least at 12 volts).

This may be why your supplier doesn't sell adapter plates any more. Past experience has shown that adapter plates without dowels or other accurate means of aligning the centerline of the motor with that of the transmission, can edge load gears and bearings in the transmission to the point of failure. Bolts alone won't align things accurately enough. If you start hearing grinding noises from the transmission, this might be the problem.

I think that the bolt and washer would keep it from slipping out, but I don't think that will be a problem, it got pushed in.

Unfortunately, because of the inherent looseness of the set screw over key coupling design, the coupling is just as likely to walk its way off the end of the motor shaft. The intermittent pressure of the throw-out bearing may not be enough to hold it in place. You should really consider the bolt-on option as it seems doable in your case.

 

[Duncan]

There are two things that could have happened

(1) the shaft has moved in the motor - This is very very unlikely but have a good look at the bits and check to see if you can move the shaft

(2) the coupling has moved on the shaft
This is the most likely problem - I hate keyed couplings like that!
Is there a shoulder further down the shaft that you can make up a short spacer to butt against the shoulder and the coupling? - or even the inner race of the bearing?

 

[PAK65]

Unfortunately, because of the inherent looseness of the set screw over key coupling design, the coupling is just as likely to walk its way off the end of the motor shaft. The intermittent pressure of the throw-out bearing may not be enough to hold it in place. You should really consider the bolt-on option as it seems doable in your case.

Yeah, I think that also sounds like a good idea, to hold it in place on both sides since I can. I was thinking I wanted to machine that coupler anyhow since the bearing in the flywheel is really supposed to be flush with the surface toward the rear and is currently flush with the coupler and sticks out a bit from the rear surface. They can just go down further to create a place for a washer to hold on.

 

[PAK65]

There are two things that could have happened

(1) the shaft has moved in the motor - This is very very unlikely but have a good look at the bits and check to see if you can move the shaft

(2) the coupling has moved on the shaft
This is the most likely problem - I hate keyed couplings like that!
Is there a shoulder further down the shaft that you can make up a short spacer to butt against the shoulder and the coupling? - or even the inner race of the bearing?

I did try to move the motor shaft and it seems firm. Thanks for suggesting to check it though. As electro wrks pointed out, it can move on the shaft in both directions. I think the clutch pressure was pushing it, so I am going to put a spacer that fits between the inner race of the bearing and the coupler.

 

[electro wrks]

Great. You're on your way to a good set-up. The alignment issue with the dowels is a tough one. If the alignment is not carefully machined into the adapter plate (usually with dowels), it's very difficult to test for it in most set-ups. The dowels allow misalignment of ~ +/- a few thousands of an inch(0.08mm) or less- which is probably a good alignment tolerance to shoot for. Unfortunately, trying to achieve this level of alignment by eye, by feel, and the variation in drilled (unreamed) holes, bolt tolerances, etc. is very difficult. And, even more difficult to repeat every time the motor is taken off and put back on. This is where the dowels really come in handy.

If your going to roll the dice and go dowelless (it sounds like you're going to try it) use a floor jack to support the weight of the motor and move it side to side as you're slowly tightening the bolts to try to find the position with the least amount of deflection and load on the transmission input shaft. Good luck, and remember this has to be repeated every time the motor/adapter plate are taken off and put back on! With an increasing probability of not getting it right every time! Garage floors and junk yards are littered with wasted transmissions from people who didn't get it right, just on this forum.

When you're putting things back together, don't forget to check the runout (wobble)on the face of the flywheel. The Miata manual will have a max for this in the ICE form.

 

[PAK65]

Great. You're on your way to a good set-up. The alignment issue with the dowels is a tough one. If the alignment is not carefully machined into the adapter plate (usually with dowels), it's very difficult to test for it in most set-ups. The dowels allow misalignment of ~ +/- a few thousands of an inch(0.08mm) or less- which is probably a good alignment tolerance to shoot for. Unfortunately, trying to achieve this level of alignment by eye, by feel, and the variation in drilled (unreamed) holes, bolt tolerances, etc. is very difficult. And, even more difficult to repeat every time the motor is taken off and put back on. This is where the dowels really come in handy.

Do you think it would be helpful to put some dowels or slotted spring pins through a couple of the holes meant for bolts in order to line them up? If the holes are accurately centered then this might substitute for dowels.

 

[electro wrks]

Talk to Canadian EV about their excellent adapter plates http://www.canev.com/adapters.php . See what they say about how important the locating dowels are. Maybe, just maybe with enough whining(and cash!) you can persuade them, if it's doable, to machine your plate for dowels on their fixtures or CNC equipment. Tell them you are absolutely going to buy their product for your next conversion and sing the praises of their company to anyone who asks about your conversion! So I don't get thrown off this forum, I should say there probably are other adapter plate makers you could contact with this problem.

 

[Duncan]

Re- Dowels

You are making too big a deal of this - dowels are not high tech!

All you need to do is
(1) - Difficult - Get the two parts into the correct position
Take your time - do it off the vehicle if you can

(2) - with the two in the correct positions drill some holes -through both parts
Then either ream the holes and use solid dowels or simply use roll pins

Then you can disassemble it and fit the parts - and you are all set up for the future

 

[electro wrks]

(1) is the problem. Back in the old days, with separate bell housings, it was fairly easy to make an adapter plate to fit just about any motor(ICE in this case) to any transmission. A novice could do it with a dial indicator, some skill, and patience. Not so, with today's integral bell housings. At least I haven't figured out an easy way to do it accurately for the typical front engine, rear wheel drive vehicle.

 

[Duncan]

Hi
It's not mine but here is my tuppence worth

Take it all out of the car
Mount the gearbox vertically - use a workbench and some wood

Take the motor off it's mounting plate
Your motor plate will have a recess or a sticky out bit to locate the motor accurately
If it hasn't then you will NEED to make something to locate the motor!

Put the motor plate onto the gearbox
You should now see the input shaft of the gearbox in the center of the motor plate - specifically in the center of the recess that locates the motor

Your job now is to lightly clamp the motor plate to the gearbox bell housing and then nudge the motor plate until it is centered on the input shaft

The input shaft will make this difficult by being a bit loose - persevere you want that input shaft as near the middle as you can get it
On the plus side the looser the input shaft is the more forgiving it will be of a small misalignment

After you have it as perfect as you can get it - tighten the bolts - then check it again
One it is perfect with the bolts tight
then drill your dowel holes!

 

[PAK65]

Talk to Canadian EV about their excellent adapter plates http://www.canev.com/adapters.php . See what they say about how important the locating dowels are. Maybe, just maybe with enough whining(and cash!) you can persuade them, if it's doable, to machine your plate for dowels on their fixtures or CNC equipment. Tell them you are absolutely going to buy their product for your next conversion and sing the praises of their company to anyone who asks about your conversion! So I don't get thrown off this forum, I should say there probably are other adapter plate makers you could contact with this problem.

I got the motor mount from them. It is great. In hindsight their adapter plate would probably have been a better idea. Thanks for the discussion, it has been helpful.

Hi
It's not mine but here is my tuppence worth

Take it all out of the car
Mount the gearbox vertically - use a workbench and some wood

Take the motor off it's mounting plate
Your motor plate will have a recess or a sticky out bit to locate the motor accurately
If it hasn't then you will NEED to make something to locate the motor!

Put the motor plate onto the gearbox
You should now see the input shaft of the gearbox in the center of the motor plate - specifically in the center of the recess that locates the motor

Your job now is to lightly clamp the motor plate to the gearbox bell housing and then nudge the motor plate until it is centered on the input shaft

The input shaft will make this difficult by being a bit loose - persevere you want that input shaft as near the middle as you can get it
On the plus side the looser the input shaft is the more forgiving it will be of a small misalignment

After you have it as perfect as you can get it - tighten the bolts - then check it again
One it is perfect with the bolts tight
then drill your dowel holes!

Thanks for the encouragement Duncan. I did as you suggested. I got it as close to centered as I could, drilled some holes through the edge of the adapter plate and the bellhousing and then used some clevis pins.

Added to that I put some machine bushings between the coupler and the motor bearing and also had he adapter machined to allow space for the pilot bearing and also, since the shaft has a center bolt hole, was able to bolt a washer on the shoulder left by the machining to prevent the coupler from moving off the shaft, as electro wrks suggested.

Got it back in the car and I can step on the clutch without any grinding, so seems like it is good so far. Thanks again guys.