120 replies to this topic

[Cooperman]

On my 1310 cc historic rally car I have a grey diaphragm, hydraulic actuation, ultra-light flywheel, 286 cam, SC CR box and a 3.9:1 final drive. It's heavy and needs quite a bit of slipping if I drive it in any sort of traffic (which I try to avoid). The CR is 11.2:1 and it really doesn't pull below 3000 rpm minimum. Max power is 117 at 6400 and I normally take it round to 7300 if I need to. Remember, it's a genuine 'S' engine with an EN40B crank and has Karl Schmidt pistons, all fully balanced.
I strip and check the engine & box after every 6 or 7 rallies and always change the centre plate, big ends and mains, with a ring change after 15 rallies.
However, it really is not a day-to-day car in any sense.

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[1977 Loud_Mini]

the set up in mine, i have a billet flywheel and backplate and a helix 190mm a grey diaphragm (aswell as a sh engineering mechanicle kit) 3.77 diff. 286 cam.
i can still slip my clutch, i can drive in traffic but to to my mechanicle linkage changing the pivot point its a very heavy clutch and when i did london to brighton my knee swelled up.
saying that i can drive for normal about 1/2 hour or so without any problems in traffic

I understand everyones opinion of setups varies thats why i would like to try this clutch out for myself as it's easy enough to change a clutch in a mini even if i would need to remove the engine for whatever reason. Just out of interest what top speed can you get up to with the 3.77 diff as i was thinking of getting one. Only trouble is the engine would be revving high at 60 and even 70.

[1977 Loud_Mini]

Cooperman your mini looks great i especially like the rally look. I don't really mind if the car doesn't produce much power below 3000 rpm as i usually rev my mini engine quite a bit as it needs it to keep up with modern traffic.

[MRA]

They don't tend to wear out that quick, the cheaper varieties can break up, or at least they used to but still worked ok, I have had several on the road with orange and grey diaphragms, can be a handful in the wet as the wheels tend to wheel spin more and with a race cam you either bog down or wheel spin for ages........ unless you have a really low ratio diff.

I did answer your PM, I will PM you.

Ah right well i guess the combination of this clutch and a 296SP cam doesn't seem like a logical option then, if i don't ask for others opinions then i'll never know what they're like unless i give it a go so thanks for all the help everyone. Regarding the PM, it never came through so thanks for answering again.

I have just sent it again )

[mini93]

top speed? not really sure had 110 on my electric speedo but i wasnt at max revs, with the 3.7 and the 10's i would be able to reach 7,500

Iv not driven it in a while so cant quite remember but i think was 4000rpm at 60 4500 for 70rpm etc so just about a 500rpm increase per 10pmh

[MRA]

Sorry, I missed your question earlier

It is not normal for a ceramic clutch to slip due to oil...... I have used a lot of helix and other makes without ever having one slip due to oil, it is the chosen material for oil immersed clutch plates for that very reason, so are you sure that the setup heights and straps are fitted correctly, ther straps need spacers which are often missed off if the flywheel has been "skimmed" or is of the lightened variety.

it will slip just not that easy to slip, more inclined to grip.... can also be seriously damaging for gearboxes and other drivetrain items.....

on the other hand a ceramic clutch will NEVER suffer with a primary or rear crank seal failure... as they are impervious to oil

do you mean all paddle clutches?

because mines deffinatly slipping and iv got a 190mm finger paddle clutch due to an oil seal issue

[mini93]

yeah, the set up is all fine and was infact working before just fine n dandy. (had to replace a trans' housing and its now apparent the seal was naffed when i changed it) Doesnt slip under normal road driving or even enthusiastic driving but short while back at combe, gave it a lap or 2 and was apparent it was getting a fair bit of slip. Its just combination of getting hot and a bit of oil on friction surface types which arent designed to run with them. Just need to find time to get round to hoiking out the old seal

[MRA]

top speed? not really sure had 110 on my electric speedo but i wasnt at max revs, with the 3.7 and the 10's i would be able to reach 7,500

Iv not driven it in a while so cant quite remember but i think was 4000rpm at 60 4500 for 70rpm etc so just about a 500rpm increase per 10pmh

My calculations are as follows....

3.765:1 final drive on 165 70 10" gives 15mph per 1000 engine revs/minute (60,000 engine revs per hour)

This would give you a theoretical top ospeed of about 113mph at 7500rpm

I think you have a higher final drive ratio than a 3.765 based on your figures, maybe a 3.647:1 or higher..

[samsfern]

i run a 3.647 final drive and find that quite good, easy to keep on cam, and cruises happily, 65mph @ 4,000rpm.

[MRA]

yeah, the set up is all fine and was infact working before just fine n dandy. (had to replace a trans' housing and its now apparent the seal was naffed when i changed it) Doesnt slip under normal road driving or even enthusiastic driving but short while back at combe, gave it a lap or 2 and was apparent it was getting a fair bit of slip. Its just combination of getting hot and a bit of oil on friction surface types which arent designed to run with them. Just need to find time to get round to hoiking out the old seal

Before you go to all that trouble.... except if its leaking it really needs doing of course disconnect the the slave cylinder from the arm, now gently by hand pull it out wards as if you are trying to dis-engage the clutch, but without putting any force on it. Now grab the plunger by the 2 15/16" AF nuts and rotate it whilst observing the arm, does it move in and out ?

If so I would also say that sometimes you may also get a little crunching whilst changing from gear to gear ?

If so changing the arm and the plunger will sort out all the problems............ except the oil leak of course.

[mini93]

Im unsure of my drop gear ratio still, i bought them 2nd hand and didnt ever count the teeth.

I asked originaly for a 3.6 but SMMC didnt have any in stock so they threw a 3.7 back in there (after i sheered 2 teeth off the old FD)

[mini93]

Before you go to all that trouble.... except if its leaking it really needs doing of course disconnect the the slave cylinder from the arm, now gently by hand pull it out wards as if you are trying to dis-engage the clutch, but without putting any force on it. Now grab the plunger by the 2 15/16" AF nuts and rotate it whilst observing the arm, does it move in and out ?

If so I would also say that sometimes you may also get a little crunching whilst changing from gear to gear ?

If so changing the arm and the plunger will sort out all the problems............ except the oil leak of course.

yeah i get crunching gear to gear but its completly normal its a dogbox

also i have no slave cylinder as the SH kit is full mechanicle and has already been set up correctly

[Cooperman]

Cooperman your mini looks great i especially like the rally look. I don't really mind if the car doesn't produce much power below 3000 rpm as i usually rev my mini engine quite a bit as it needs it to keep up with modern traffic.



Actually with a 296 it won't produce much useable power below about 4000+ rpm (look up the cam profiles and graphs on the Kent Cams website).
You are certyainly going to have to drop the diff ratio, so your top speed and cruising speed will be lower than, say, a 1380 with a 266 or 276 diff because of the need for lower gearing. So, you will probably need to be cruising at around 5500 rpm which, on say a 3.76 diff will be around 85 mph. To keep up with modern traffic, if that traffic is going relatively quickly, you will need to use 3rd gear a lot and 6500 to 7000 rpm to get it onto the cam. It will give of its best, assuming a really good head, at between 5500 rpm and 7200 rpm. At below 5000 rpm the acceleration will not be very good, but that's why you have a high overlap cam to give real serious top-end power for the track. With my 'S' I cruise at around 4200 rpm if I use it on the road in order to keep engine wear as low as possible and that is a cruise speed of about 60 mph in top.

[1293sleeper]

On my 1310 cc historic rally car I have a grey diaphragm, hydraulic actuation, ultra-light flywheel, 286 cam, SC CR box and a 3.9:1 final drive. It's heavy and needs quite a bit of slipping if I drive it in any sort of traffic (which I try to avoid). The CR is 11.2:1 and it really doesn't pull below 3000 rpm minimum. Max power is 117 at 6400 and I normally take it round to 7300 if I need to. Remember, it's a genuine 'S' engine with an EN40B crank and has Karl Schmidt pistons, all fully balanced.
I strip and check the engine & box after every 6 or 7 rallies and always change the centre plate, big ends and mains, with a ring change after 15 rallies.
However, it really is not a day-to-day car in any sense.

You have me worried now as thats pretty much the same spec as my engine other than the flywheel which will be done soon plus my engine is 1293 and i live in the middle of a city so can't avoid traffic

i have been told at 11.3:1 cr which my car is i'll have to run high octain fuel do you


ps sorry for high jack

[Cooperman]

I always use the 97 or 98 octane petrol with an octane booster as well to avoid the risk of blowing a piston due to detonation.
Distributor is an Aldon Custom-built one to give sufficient mech advance. Remember, I run to historic regs which means I have to use points ignition.
Mine was 1293 until its last rebuild.
I have to say it is not at all nice in traffic and I try to avoid town driving at all costs. In fact, it goes most places on the trailer if it's more than about 60 miles each way - like to and from rallies. It really has no useable top speed on ordinary roads, but on a rally at 6500 rpm on gravel it is just fantastic.
I also have an Innocenti Cooper 1300 and a twin-box RC40 exhaust. It has a 3.44 diff, standard ratio early 'S ratio helical box, is 1330 cc with 10.3:1 CR, a slightly 'cleaned-up' head, twin 1.25" SU's, a 3-into-1 manifold. I have to say that it is a real pleasure to drive and keeps up well with modern traffic. I much prefer it to the rally Cooper 'S' for road driving which is much nicer on the road. It is LHD as all Innocentis were.