# Clutch adapter design ideas



## dtbaker (Jan 5, 2008)

cts_casemod said:


> Hi guys,
> 
> I am overhauling my VW polo and I'm going to take the clutch out during the process.
> 
> ...


why are you set on going clutchless? retaining the clutch adds a little weight, but provides a good solution for minor alignment issues, some 'give' in the system stop/start, and another safety feature to disengage motor in a runaway condition from throttle or controller failure.


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## evmetro (Apr 9, 2012)

I went with solid, but I also piled my motor, tranny ad clutch into my car and took it to the best machine shop in town where I explained everything to them. Everything came out super precise.


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## dillond666 (Dec 27, 2010)

I had a quick google and it didn't look like the polo mk3 gearbox has a pilot bearing. Quite often front wheel drive gearboxes don't have one because the input shaft is held between two well spaced bearings.

I used an HRC90 style coupling on my car. these come unbored or taperlock. I bought two unbored ones and machined them myself, one keyed the other splined and shrunk them onto the respective shafts. I got them here:
http://www.bearingboys.co.uk/Couplings_-_HRC_Style-1661-c

Haven't broken them yet (warp9 zillaZ1k)

I am going on the assumption your motor to gearbox alignment is perfect.


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## cts_casemod (Aug 23, 2012)

dtbaker said:


> why are you set on going clutchless? retaining the clutch adds a little weight, but provides a good solution for minor alignment issues, some 'give' in the system stop/start, and another safety feature to disengage motor in a runaway condition from throttle or controller failure.


Im on an AC system.
After a few pages of debate about runaway conditions, I just decided I could not afford one. Also the clutch pedal is still there and kills the output for the motor.

As with the clutch... Yes, I thought like that, so I started with a clutch, but in six months never really got to use it, so its one thing less to go wrong.



evmetro said:


> I went with solid, but I also piled my motor, tranny ad clutch into my car and took it to the best machine shop in town where I explained everything to them. Everything came out super precise.


How many miles since then?




dillond666 said:


> I had a quick google and it didn't look like the polo mk3 gearbox has a pilot bearing. Quite often front wheel drive gearboxes don't have one because the input shaft is held between two well spaced bearings.
> 
> I used an HRC90 style coupling on my car. these come unbored or taperlock. I bought two unbored ones and machined them myself, one keyed the other splined and shrunk them onto the respective shafts. I got them here:
> http://www.bearingboys.co.uk/Couplings_-_HRC_Style-1661-c
> ...


Just the clutch bearing, altought I am not using the tiny Polo gearbox. I am using one for the passats. Do you have a thread page with the work you done? I am curious about that setup


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## dillond666 (Dec 27, 2010)

cts_casemod said:


> Just the clutch bearing, altought I am not using the tiny Polo gearbox. I am using one for the passats. Do you have a thread page with the work you done? I am curious about that setup


Unfortunately I didn't document the coupling/bellhousing. I do have a few pictures which will give you an idea of the arrangement. As mine was on a rear drive gearbox I put a brass bush in the end of the motor shaft to support the gearbox input shaft. Please don't think the rusty plate went on like that! I welded the assembly together and turned the whole lot on the lathe with a temporary jig to make it all concentric to the input shaft bearing, then dowelled it to the gearbox casing.


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## cts_casemod (Aug 23, 2012)

dillond666 said:


> I do have a few pictures which will give you an idea of the arrangement [...] I welded the assembly together and turned the whole lot on the lathe with a temporary jig to make it all concentric to the input shaft bearing, then dowelled it to the gearbox casing.


Never seem a bush like that. How does it attach to the other bit on the gearbox!? Mine is a bit tricky its 38mm so I need a huge metal adaper. Thinking in just using something to attach to the crackadapter already on the motor, so i dont have to machine another adapter. 

Pics:


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## dillond666 (Dec 27, 2010)

If you look at the bearingboys site, you could use a 1610-38 taperlock bush and an HRC-110 coupling. That would go directly onto your motor shaft with no machining.
Get another pilot bore HRC-110 and bore and spline it then shrink it onto your gearbox input shaft.

The coupling halves don't bolt together the three drive dogs just mesh with each other and there is a rubber spider in between for vibration damping. The rubber also permits minor misalignment but we don't want to go there.

Splining the other coupling half can be done on a lathe but it is tricky. You make marks on the periphery of the lathe chuck (lightly centerpunch calculate with dividers) corresponding to the number of splines(best on a big chuck) set a pointer to it and you arrange a wooden wedge to lock the chuck to the bed (crude but effective ).
Grind a tool to the correct profile (by eye) and put it on the end of a boring bar.
You then use the saddle to make the cuts and the crosslide to vary the depth of cut. The chuck is turned between cuts round your index marks on the chuck and locked in position each time. At no point during the splining process is the chuck powered round, leave the machine in neutral. Takes a wee while but it works. Couplings are grey iron so it machines easily. I measured the major and minor diameter of the gearbox shaft and used them to get my starting bore size and depth to cut splines (including interference fit allowance)

Wish I had done a video now .

When you say you are using the passat gearbox, do you think the original was too weak? I fancied converting a Citroen C1 but was a bit worried about strength. What do you think?


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## cts_casemod (Aug 23, 2012)

dillond666 said:


> If you look at the bearingboys site, you could use a 1610-38 taperlock bush and an HRC-110 coupling. That would go directly onto your motor shaft with no machining.
> Get another pilot bore HRC-110 and bore and spline it then shrink it onto your gearbox input shaft.
> 
> The coupling halves don't bolt together the three drive dogs just mesh with each other and there is a rubber spider in between for vibration damping. The rubber also permits minor misalignment but we don't want to go there.
> ...


Hi, I understand how it works, just confused on how you kept the two halves together, as they dont seem to be fisicaly secured to each other.

I have a 1610 BF16 that I used for some tests back when I started the conversion. You are right, if fits okay, but it is way to heavy at about 2.5KG for the complete setup. Not as much as the clutch, but still unnecessary weight that i want to avoid, since balacing the whole thing would cost a small fortune. If I go that route I plan to have an aluminium adapter to hold the actual spline and drive both motor encoders as well.

I have the metalic center for the clutch so all I have to do is cut it, make it round on the lathe to make sure is centered and weld into the bit that holds to the bush. Makes it a bit easier  In fact if i go with the tapper lock I will use the whole assembly with the springs, but i need to think this wiselly because the engineering shop takes quite a good money, including to think, so I need to be well clear in what i want done and be well clear when I say I want this, done no need to rethink that 

The Polo 085 gearboxes are a comon failure and mine was no exception. Twice. I wanted something more reliable to handle the serious torque my motor puts out when stopping the car. Add to the fact that it was to small to fit the electric motor without major modifications, but again that was another thing that had to be add to the conversion (mounts, driveshafts, balance, etc) and it took me quite a while. So if there are no known issues with your C1 gearbox and your motor fits I dont see the reason for the hassle.


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## electro wrks (Mar 5, 2012)

dillond666 said:


> .
> 
> Splining the other coupling half can be done on a lathe but it is tricky. You make marks on the periphery of the lathe chuck (lightly centerpunch calculate with dividers) corresponding to the number of splines(best on a big chuck) set a pointer to it and you arrange a wooden wedge to lock the chuck to the bed (crude but effective ).
> Grind a tool to the correct profile (by eye) and put it on the end of a boring bar.
> You then use the saddle to make the cuts and the crosslide to vary the depth of cut. The chuck is turned between cuts round your index marks on the chuck and locked in position each time. At no point during the splining process is the chuck powered round, leave the machine in neutral. Takes a wee while but it works. Couplings are grey iron so it machines easily. I measured the major and minor diameter of the gearbox shaft and used them to get my starting bore size and depth to cut splines (including interference fit allowance)


Sometimes you get lucky and the lathe spindle bull gear(if it's exposed) has a multiple of the number of splines that need to be cut. A bolted-on stop with a wedge that fits between the gear teeth could be used to lock the spindle in each cutting position. You might be able to find or make an indexing plate, with different spaced holes corresponding to the number of splines, to bolt on or clamp in the chuck or spindle.


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## dillond666 (Dec 27, 2010)

cts_casemod said:


> Hi, I understand how it works, just confused on how you kept the two halves together, as they dont seem to be fisicaly secured to each other.
> .


Both halves are an interference fit on their respective shafts. I did some careful measuring to ensure the correct axial position (using bellhousing face as datum), heated them up and slipped them on.

@electro wrks, Good points for a more refined technique.


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