Lt77 conversion requirements

I think l have both types of P6 pressure plate. The individual springs type & the pointy plate spring type. And l think you'll find that's what they're actually called.

Indeed, those are the correct terms, but AFAIK the P6 never had individual springs type, only the pointy plate spring type, either with or without the flat platey thing in the middle.
 
Ah, well l may have a correct pointy thing then but not a suitable platey thing so that's another item to add to my current never-ending automotive shopping list. :rolleyes:
 
Can anyone shed light on a good/surefire way to ensure I don't get a heavier clutch pedal with the LT77 conversion? I can add that I've got an uprated clutch kit from Clutchfix LTD that will be 10-15 pct heavier than stock, and from what I understand, using the P6 slave will make the pedal harder already?
Thanks Harvey, in that case I'll get hold of one and figure out an adapter between the P6 line and SD1 inlet port. I've read about the thread sizes somewhere...
 
The pointy finger pressure plates have diaphrgm springs, rather than the old coils. Also interested in how to avoid a heavy clutch in this conversion - when I did it last some 25 years ago I got a very heavy clutch, put it down to being given a truck type pressure plate. Now I know more, it might have been due to not removing the 1/4" off the slave mounting....
The SD1 m/cyl is 5/8" bore, the slave 7/8". The P6B m/cyl is 0.7" bore (slightly bigger than 0.625)...dont know slave bore? Leverage ratio of the throwout arms is also relevant if trying to compare loads here.
 
Diapragm spring clutches should give a lighter action than coil spring ones as the diapragm has a certain amount of self assistance in its range of travel that the coil spring doesn't have.
 
I do have a new pressure finger cover which l have already taken over to Rich Moon's place though we're a'ways off from that point yet. But if anyone has a new 2000 Sd1 driven plate then let me know. I'll put a post in the 'wanted' section too.
 
This prop shaft alignment thing was bugging me, so I eventually found the alignment mark highlighted in green after a little investigation. 1st photo shows the rear arrow aligns with the front arrow. The photo shows it slightly off but it is just the camera lens distorting things.
The second photo is now confusing me because if I follow earlier posts the yokes of each end of the prop shaft should be in phase, however if I do that then the alignment arrows are way out, and as you can see the rear end of the prop shaft yokes are something like 45deg offset from the front.

 
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That's precisely the point of the arrows, the UJs aren't supposed to be in phase.

Thanks for confirming. I was under the impression they should be in phase after reading this thread, but maybe it’s just me that’s read it incorrectly
 
Re the need for a spacer under the clutch slave - the Chris Gregory notes say he didnt use one. What would be the sign that one is needed? I have 2 push rods. One I have shortened 1/4", but if that turns out wrong I dont fancy pulling the box to fix it, so now plan to fit the full length spare rod, and be ready to fit a spacer - but how do I know its needed?? Hard pedal, failure to separate? Fit a spacer first, and suck it and see?
thanks
 
Here is my latest thinking. I have a New steel 22lb flywheel (ex USA) - total thickness just on the spec min of 29mm. I have a 3.9 block handy, and the LT77, and clutch. Bolt the flywheel to the 3.9, fit the clutch, and offer the LT77 up. Check the position of the push rod and its fit in the slave cyl. What am I looking for here? If the slave piston is NOT bottomed with the throwout brg in contact with the fingers - no spacer needed? If bottomed, fit spacer until its not bottomed? All this with the std length push rod.
Comments please.
 
Offer the LT77 up? Why not just bolt it on, then check the slave cylinder.

Don't forget you need the smaller ID spigot bush
 
Thats what I meant. I have a correct spigot bush...the lt77 pinion fits it (but it might not after its driven into the crank), but the dummy for aligning the driven plate doesnt, so I made one out of alloy hex bar I have. I suspect I will have to modify the plastic aligning tool before its used in anger. I drilled the dummy bush 1/2" (well used drill), and it fits the pinion, so its the aligner thats wrong.
Is the rest of my test logic OK?
 
Thats what I meant. I have a correct spigot bush...the lt77 pinion fits it (but it might not after its driven into the crank)

Stick in the freezer overnight and it should tap in without changing shape.

TBH I haven't fitted an LT77 for a while. Sparky has one but it was in when I bought the car.

When I did fit one, back in the early 80's I just went to the scrapyard and whipped a box out of an SD1. I used the SD1 clutch and spigot, and just bolted it in. I had dimensions of a spacer plate but no tools to make one, so just used some washers. I do remember stripping the thread of one of the bolts holding it as it had 1/4" less to bolt into, so worked out the thread and bought some longer ones. I got an auto prop when at the scrapyard, and this just bolted in.
 
Hi, Similar tale when I did mine. I bought a rusty manual V8 SD1, Engine was refreshed and went into a Land Rover. The Gearbox, flywheel and new clutch went into the P6b complete with the Sd1 slave cylinder and got a clutch pipe made up to connect P6b master to slave. The rear axle eventually got cut and shut to go under the back of a RV8 engined Mk1 Cavalier.

In those days days you just used what you could find, I sometimes think some people over think it. Although having said that it used cars were easier to pick up.

Colin
 
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