Clutch release bearing

[John Vine]

2 hours ago, Colin_T said:

Is it bellhousing off ?? 
 

answered my own question. Yes bellhousing off.

i assume it only needs a light smear of silicone on refitting around the selector fork o ring and mating faces, Not the 18gallons of sealant mine had holding it on - let’s just say it didn’t need the bolts 😅 

You assume correctly.  This is what the Assembly Guide says:

The gearbox face needs just a thin coat of silicone sealant, but do ensure the O-ring is well coated:

JV

[Colin_T]

even with bellhousing off it’s still VERY tight to slide off the fulcrum pin. Probably use a little relief around the top hole where the fork pokes through so it can pull forward a little more, and the recess itself the fork retracts into when fully back could use a little relieving, but even still its bell housing off for adequate clearance on the gearbox nose and inside of the fork. 

[John Vine]

Could you pull out the fulcrum pin?  Or even remove its little plastic sleeve (plus some heat, I imagine)?

ETA: This thread is about fitting the modified fork.  Maybe some of the steps could be reversed?

JV

Edited June 16 by John Vine
Add thread link

[Colin_T]

No plastic sleeve on mine, just metal. It’s certainly not going to fall off in a hurry that’s for sure. 
 

whilst the bellhousing was off I’ve given it a damn good cleaning inside and out . 
 

I still decided to opt for the heavy duty bearing. Just been modifying it in the lathe, it’s now currently in the freezer chilling before I press the bearing onto it. The total assembly from where it sits on the clutch fork to the face of the bearing is less than 1mm taller than the original item, so shouldn’t effect me at all. 
 

they only make one now extended for use with lower profile 184mm clutches, it has an 8mm step. So I turned this off leaving a 0.5mm step to make sure only the inner part of the bearing sits on the step so the bearing doesn’t scrape on it. Then turned down the total length so doesn’t bottom out on the outer face which has a smaller ID than the actual bearing part.

it also has no clips on it to secure it to the fork, although it is a very tight fit. I was thinking all manner of ways to secure it, sprung mechanisms, circlip grooves, and more… then I decided to keep it simple…. 
lock wire, long enough so it allows full bearing angle movement, short enough so can’t foul on the spinning bearing. 


 

 

Plan is to get the engine back in tomorrow and sort out my clutch pedal springs for pre load. 

[Colin_T]

 

also made sure to check release bearing ran smoothly up and down on the gearbox nose before fitting the bellhousing back on. Didn’t want it to be too tighter fit just incase warm up expansion differed between the steel and the aluminium and caused it to nip up when warm or something.

 

looks fast, and followed the old Japanese proverb:

”take lots of pictures, make car go faster” 

[John Vine]

Very neat!  I take it you're no longer opting for the PGM uprated fork?

What CRB is that?  And is the pressure face a good match for your diaphragm fingers?  It looks to have quite a slope.

Re pre-load, the CQ13 spring is no longer available (as you're probably aware).  I did a search for possible alternatives, and came up with these:

https://www.trgb.co.uk/collections/all-parts/products/brake-clutch-pedal-spring

https://www.moss-europe.co.uk/spring-pedal-return-057950.html?assoc=124820

https://www.moss-europe.co.uk/spring-clutch-arm-return-1g5999.html?assoc=343932

Of course, they may be unsuitable (wrong spring rate, wrong dimensions), but if you do find a suitable spring, please let me know the details and I'll update my pre-load Guide.

JV

[Colin_T]

Thanks JV. It’s a burton one. It’s a rounded bearing but using rounded bearing on round clutch fingers is ok. It’s flat fingers against flat bearing where problem occurs.

there was another bearing which had slightly lower profile (still rounded) which I may try, I bought 2 of the aluminium carriers so I can make a mk2 version if need be. 

My fork looked ok so left it be. 

[Wrightpayne]

The PGM fork looks a sturdy item compared to the original which has a history of failing.

Not too late to order one!!

[Colin_T]

so on mock install I wasn’t happy with the ammount of return travel left on the clutch fork, infact it was next to non existent, probably less than a mm !

as the clutch wears the fingers become higher, if the clutch fork can’t return further back all that will happen instead it will begin to engage the clutch.

i removed the bearing and done a bit of modding in the lathe to the bearing to reduce its overall height by 2mm. (Its also now a bit more of a flat face bearing too)

it now mimics almost exactly the height of the original bearing and now I have some excess play in the clutch fork to allow for clutch wear, heat expansion etc.

It’s been repacked with redline CV-2 which was always my go to grease. Excellent for high pressure, high temp, high speed applications. 

 

 

Edited June 16 by Colin_T

[SLR No.77]

As per Wrightpayne’s comment about the PGM clutch fork, it’s a highly recommended modification. Failure of the standard d/s clutch fork is common and when it does its engine out again to replace it.

Stu.

[2cv7]

[Colin_T]

So got round to sorting my clutch CRB pre load spring out.

i had ordered some triumph TR6 ones but these were too short and heavy.
I ended up being able to use my original one and just change the mounting position and length accordingly, plus a bit of modding with some pliers to form the ends etc.

It now attaches to the cable clevis but still the original holes in the pedal box for the spring. 

I used a borrowed force meter so I could press on the clutch pedal where the cable attached, then multiplied my readings by 2.5 (the ratio of the clutch fork:CRB) 

I aimed for 40N at the top of the clutch pedal, so would put me in the middle of the 80-120N range  (40 x 2.5 = 100) 

had to modify my clutch pedal stop as this now fouled the spring, so that had a quick visit to the lathe to turn the “washer” down. 

 

[John Vine]

Well done!   And looks similar to my own solution from years ago:

 

My only comment would be that your spring appears to pull at an angle (A) to the clutch cable.  That will reduce your nominal 40N pull to 40cosA. 

Did you manage to discover the recommended pre-load figure for your Burton CRB?

JV