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I have read all the posts about clutches in BEC's, I have a MK with 2006 R1, new owner I did not build it. I have started to drive it and seem to have the same issues, start off kill it, start off kill it.... The clutch cable goes from the bottom of the peddle box on the floor, to the clutch housing on the motor. is there a better way to route the cable, that will make clutch use more car like? I have seen some pics of a cam type mount the cable passes over, anyone use this, does it help.

I have no practical help, but know a lot about bikes. Is you current cable smooth in operation, nothing is worse than a notchy cable, assuming your cable is smooth. I would start by trying to define the clutch cable movement that the bike would have originally had. It's not much probably 1/2"? See if you can find a clutch perch and check the movement. Then see what your pedal is moving. Are they about the same? Getting the pedal to mimic the hand lever is about all you can do. I would guess your pedal has to much movement so it's not very sensitive. You can probably lengthen/shorten the clutch lever on the engine or the pedal assembly to match the throws.

Hope this helps.

Graham

Thanks Graham,

Cable is like new, I'll try your suggestions, thanks

George

I found some pics of the MK Indy clutch system though I don't know if it will be the same as what you have. If you'd like engineers and mechanics to look over the car for potential improvements, post or host some pics.
First determine if the pedal ratio can be increased and still provide enough pedal travel.

The cable kit is a diy assembly on both ends and the ends can come off depending on how it was assembled. Imho, the cable is too thin for a clutch but it should work for a while. The cable should be greased with wheel bearing grease in the sheath (as best you can), the clutch arm where the cable drum is installed and the pin for the clevis in the pedal (so the drum and clevis will rotated easily without bending the cable every time the clutch is pressed, eventually breaking the fine wires). Adjust the engine end of the cable so the pedal is lightly touching the pedal stop.

Press the pedal until it runs out of travel at the engine end. Do not press too hard or you can break, stretch, or damage the cable. There should be an adjustable pedal stop that is designed to limit how far you can push the pedal to prevent cable damage. If the pedal does not run out of travel before the engine end (i.e., a couple inches left before hitting the firewall with the front of the pedal with the stop shortened/removed), the pedal ratio can be increased.

The pedal ratio can be increased by drilling a new hole closer to the pivot bearing if there is enough clearance to the clevis and, with the pedal full pressed to the firewall, the clevis does not hit the pivot bearing housing and force the cable to bend each time, which will cause the cable to fail prematurely.

A direct fit cable end instead of a clevis would allow for a higher pedal ratio without cable failure. The cable end would lay far enough around the pedal pivot boss that the cable does not flex where it enters the cable end.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

The 3 pics show the pedal set up, the frame bar to left of pedal, acts as a stop, the second pic shows the motor side. I had my wife push the pedal, have 4 inches of movement on the pedal, about 1 inch on the motor side for engagement.

It looks like I could move the clamp above the pivot bolt, by an inch, or as you suggested use the pivot bolt to secure the cable. Similar to the brake pedal, would higher be better?

You could wrap around the pivot to clamp to upper side. This would increase the ratio to the minimum for the pedal and should have no clearance problems and improve the cable life.

Perhaps this is an older Indy kit or the PO made some parts substitutions and/or left a few bits off.

I see nothing to keep the clutch pedal from falling too far except the pinch bolt for the cable. There should be a U shaped metal bracket that bolts on with the pivot bolt and sit on the floor. This is the pedal "up" stop.

The pedal "down" stop on the firewall should be a long bolt with the head toward the pedal, with a jamb nut against the firewall and another nut in front of the firewall to hold the setting. Looks like he just put a bolt in the hole. I'd probably fit a standard low-grade 3/8x2.5 bolt, two washers, and two nuts.

It looks like there is a pinch bolt instead of the clevis. Using a pinch bolt this way will cause premature cable failure because it will flex back and forth at the bolt. Wrapping around the top to clamp like described will limit the flexing to the large radius around the pivot boss.

Once we have stops, the pedal can be adjusted.

I'll draw a picture to clarify.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

I don't see the cable adjuster bushing in the hole in the firewall for the clutch cable. I need to see the other side of the firewall. Adjustment should be with the cable housing length and there is currently no way to do that.

An easier alternative to the pedal mod and making parts is to order a clutch cable kit from MK and the adjustment bushing but it may take a while to get here. The bush is just a plastic rod that is a snug fit to the firewall hole with a flange edge to keep it from pushing through. It also requires tapping to accept the threads on the MK cable housing.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

http://www.mksportscars.com/parts/cable ... ersal.html

Looks like the cable kit includes everything but the connection to the engine could be an issue in either finding an end fitting to engage the r1 swivel or grinding off the pin to remove the r1 swivel from the r1 clutch arm in order to use the MK supplied clevis and a new pin. You may be able to use the r1 cable with the MK parts.

In a nut shell, add the down stop bolt, change the pinch bolt setup, and fit a housing adjuster.

If you don't care right now if the cable breaks and just want to drive it:

Loosen the pinch bolt.
Rotate the pedal "up"toward the driver as far as it will go (probably about 30 degrees).
Pull the cable lightly to eliminate the slack.
Tighten the pinch bolt.
Press the pedal by hand as far as it will go before resistance is felt.
Adjust the "down" stop to touch the front of the pedal, then lengthen one turn and snug the nuts.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

WOW, thank you for taking the time to help me fix the issue. It has been discouraging trying to figure out what the fix might be, I was afraid I would burn out the clutch, continuing to drive it.


George

I would rather fix it right. here are pics firewall side.

Looks like he made a bush to fill the hole and provide a shoulder stop for the cable housing but no adjustment.

What is the diameter of the cable housing and the hole in the firewall? Either a crescent wrench (for OD) or string and a pen (for circumference) with a ruler can help you to measure that.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

I'd just use the r1 cable, loop the cable to the top of the pedal like I drew, make a new bushing starting with uhmw rod a 1/2 inch larger than the hole in the firewall (guessing 1.5"od rod for 1" hole?), od turned down to fit but leaving a 1/4 inch thick thrust flange, drilled and tapped to accept an R1 sized, two-piece clutch cable adjuster (must be a 2 piece to jamb) like this (m8-1.25 I think?):

https://www.ebay.com/itm/193841569629?h ... R_b9toDgYA

https://www.mcmaster.com/8701K47/

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

Both are 3/4 of an inch

So I would drill a hole in the pedal arm above the pivot point, loop the cable on the pivot point bolt, and secure the end to the new hole in the pedal, correct?

The cable housing is the black sheath over the cable. The white part in the hole is the bushing.
The size of the center hole in the white bush would be the same as the cable housing. If using an R1 adjuster, it will match. You may be able to just tap the white bush to accept the r1 adjuster if the plastic is reasonably hard material but I doubt it. You could have the bush made from aluminum instead.

The cable would loop around the pedal pivot boss up to the pedal arm and be secured under a large washer with a 1/4 inch bolt. Don't want to make the hole any bigger than needed to secure the end of the cable.

EDITS:
FWIW, my pedal ratio verbiage on higher/lower and increase/decrease were reversed but the results of the pedal mod are correct. Clutch cable closer to the pivot= pedal ratio increase=more pedal travel for the same throw at the engine=softer/easier pedal application. These mods increase pedal ratio, improve cable life, and eliminate the slack in the cable that wastes travel.

I think you will be pleased but if after all this, full pedal travel stop to stop is not enough to lurch when selecting first from neutral, then we need to either; fit a clevis to the pedal in the original location where the pinch bolt was; and/or look at the "up" stop bolt arrangement to possibly bring the pedal closer to the driver for more throw and even with the brake pedal. Some installed pics of the pedal and adjuster would be good to share also.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12