Author Topic: Primary chain clearance  (Read 3212 times)

Offline Rocket Racer

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Primary chain clearance
« on: 26.08. 2010 08:05 »
Mocking up my swing arm A10 clutch, there is bugger all clearance between the inner case and the chain around the clutch area. I could hear the chain fouling the case - probably the sliding plate.
Is this lack of clearance common? should there be much room here. the heavy plate chain I'm using is contributing, but even a light chain doesnt resolve the issue completely.
My frame doesnt have the rear bottom support for the inner primary chain case so it may not be sitting exactly where it should.
In practice its not a major for me as I can run a cut away inner case and run the clutch dry for racing, but I was surprised I had no clearance ...
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Offline muskrat

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Re: Primary chain clearance
« Reply #1 on: 26.08. 2010 10:25 »
G'day RR,
               there should be a good 3/16" - 1/4" clearance. Check the motor/gearbox allignment. What main shaft and clutch have you got ?
Cheers.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Muskys Plunger A7

Online chaterlea25

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Re: Primary chain clearance
« Reply #2 on: 28.08. 2010 23:54 »
Hi, Rocket Racer,
Primary or secondary chain???
Do you have the spacer plate between the crankcase and inner primary fitted?
original (Renold) primary chains are around 15mm wide, modern HD chains are up to 20mm!!!
Have you checked the primary chain sprocket alignment with the inner case removed???
There are several different depth clutch centres and at least 2 different drive sleeves for the cush drive on the crank
This topic has been well covered on the forum
HTH
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Rocket Racer

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Re: Primary chain clearance
« Reply #3 on: 29.08. 2010 00:11 »
Thanks guys, the issue is with the primary. the engine and gearbox plates are not yet fully tightened up. but the spacer behind the cush drive on the crank is the thicker type and with my clutch I ended up needing to space out the cush drive sprocket even further to get the alignment with the suzuki clutch sprocket right.
The clearance issue was with the sliding plate. With just the two bolts inside the inner primary chaincase to the crankcases attached the case alignment was not the best.
I'll come back to this issue once I'm happy with the rest of the assembly as one every thing is tightened up it may resolve itself.
For the time being I have a non renolds heavy plate race chain fitted, I may even fit an o ring chain if I decide to run the clutch dry.
I have half a dozen inner chain cases so have  *whistle* cut the back out of one of the most knackered ones so I have no clearance issues for the time being.
I did have visions of running a wet clutch if I could get it oil tight for racing, but may revert to the low effort solution of just lubricating between races.
I am currently fitting the steel ring plate behind the primary. I suspect I could dispense with this.
My engine plates are all std swing arm type, although my frame is replica BB32R not swing arm.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Offline muskrat

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Re: Primary chain clearance
« Reply #4 on: 29.08. 2010 14:13 »
G'day RR,
                I think you will find an O ring chain will rob valuable power. I just used the cheapest chain and gave it a good lube before each race. I would get about 2 meetings (10 races) out of a $30 chain.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Rocket Racer

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Re: Primary chain clearance
« Reply #5 on: 29.09. 2010 02:07 »
Seems a shame to start a new thread, so a question to anyone running a suzuki clutch.
The distance between the clutch hub and the outer pressure plate has a defined minimum distance when the clutch bolts are done right up. Can someone confirm the number of plain and friction plates I should have and also the thickness required for these plates.
As supplied by a wrecker I was initially given 6x friction and 5x plain plates, but when assembled this was insufficient for any plate tension. adding a 6th plain plate has given me some clutch plate friction, but not enough to prevent slip, although there is adequate to run up the bike (with a tow start) .
The clutch is running dry and the plates are clean and appear serviceable.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Online chaterlea25

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Re: Primary chain clearance
« Reply #6 on: 29.09. 2010 22:19 »
Hi Rocket Racer
Which model / year did the Suzuki clutch come from?
I have a couple of them in boxes in the workshop and can check tomorrow
The Suzy clutch is meant to run in oil, I dont know how it will react running dry ???? ????

Cheers
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Rocket Racer

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Re: Primary chain clearance
« Reply #7 on: 29.09. 2010 22:31 »
I was told gs550, not sure of year. If I can sort out my chain clearance I can revert to wet primary, the inner case currently fitted doesnt have a back in most of it! but not a biggie to swap over
Worst case I'll lube the top hat bearing and chain between races.
I suspect I need a 7th friction plate...


Hi Rocket Racer
Which model / year did the Suzuki clutch come from?
I have a couple of them in boxes in the workshop and can check tomorrow
The Suzy clutch is meant to run in oil, I dont know how it will react running dry ???? ????

Cheers
John O R
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Online chaterlea25

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Re: Primary chain clearance
« Reply #8 on: 30.09. 2010 20:50 »
HI Rocket Racer,
OK just loooked at the GS550 clutch, it has 7 friction plates, 6 plain in between them,
the stack of plates comes almost level with the outer edge of the basket.

This GS clutch does not have cast in the steel splined centre as on the GSXR clutches, the boss in the centre is too small to machine out to fit the BSA centre,
How did you mount the suzi clutch onto the BSA centre?
I am waiting on a BSA splined mainshaft with a view to using that instead of the taper fit one???
splined sleeve inside and out?????

Regards
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Rocket Racer

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Re: Primary chain clearance
« Reply #9 on: 30.09. 2010 22:41 »
John,
thanks for confirming 7 friction plates. I figured this was probably the problem as the existing plate stack has marginal contact from the outer pressure plate before it cannot go any further.

You raise an interesting point re these clutch's, from their proliferation it would appear they are a doddle to fit, but on sourcing the GS550 clutch my engineer and I did a fair bit of head scratching regarding centres.
We did consider they would fit better on the splined type shaft, but I dont have any but do have a stock of tapered ones.

We resorted to making a new centre, boring the Suzuki one out and using four straight keys  to lock the centre and the clutch hub. We also had to make a sleeved nut that can screw inside the hub.

I'll see if I can take some pics. I'm sure some of our experts have done something better but it seems to work.
We did re use the suzi basket but removed the outer steel support wheel, made the basket narrower (as the primary chain case wouldnt fit, then reattached the steel band (assuming it was there for a purpose)
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline Rocket Racer

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Re: Primary chain clearance
« Reply #10 on: 01.10. 2010 01:32 »
Back to chain clearances; having had the bike run up, I now have a list of "to do's", one of which was to look at the lack of chain case clearance on the inside. Part of my issue is that my bike is made up of other peoples off casts and hasnt been together as a unit over the various parts lifetimes.  Looking carefully at the inner primary I had tried before, its evident that the front mounting area by the two rear bolts is distorted towards the engine which is then magnified by the back of the chain case into an alignment problem. I also do not have a frame mounting point for the lower rear chain case mount, which I presume might have helped matters.
Looking at my other inner primaries most appear to be distorted to some extent around the two rear bolts. I've taken one of my better cases (checked against a glass plate with some fine grinding paste) and with some judicious hammering have got the case showing a flatter surface.
It also appears that with my rigid replica frame I may be able to dispense with the packing plate between the primary and the engine - subject to some mocking up checks. At this point I will aim towards trial running the clutch wet for cooling and wear reduction before the bike takes to the circuit proper.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Online chaterlea25

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Re: Primary chain clearance
« Reply #11 on: 01.10. 2010 20:40 »
HI Again Rocket Racer ,
Here are some pics of a "Pearson" manufactured Suzi clutch for a BSA, you can see that the chainwheel and basket are manufactured as one piece,and the bearing is held in place with 2 plates and screws,
The centre is opened out to fit the BSA steel centre splines, There is a hardened washer between the bearing and the centre, you would then need a substantial washer to cover the join between the two behind the nut
The Suzi centres on these must have a bigger boss like the GSXR 750 ones ???? ???? ????
I didnt know they were that different at the time  *conf* *conf*, The GSXR centres will take the same plates on the centre as the GS550, *smile* (plates that fit the basket are different!!)
So I was hoping to get another  GSXR 750 centre and work on that *ex*
I have a couple of GSXR 750 clutches but not enough centres to complete the batch of clutches I need  *sad2*
THe GSXR clutches I have are from the cable operated models circa 1990??
These have a solid outer basket, If I have to narrow these I will have to remove the same amount from the centre and/or pressure plate to give the same spring pressure

I saw this clutch on an autojumble stall even though there was substantial wear on the sprocket he still wanted £270 for it *ex* *ex*, I asked if I could take some pics of it and he was ok about it *smile*, I snapped up a 30mm Mikuni kit he had for £65 *smile* *smile*

More pics in the next mail
Cheers
John O R


1961 Super Rocket
1963 RGS (ongoing)

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Re: Primary chain clearance
« Reply #12 on: 01.10. 2010 20:42 »
more pics
1961 Super Rocket
1963 RGS (ongoing)

Offline Rocket Racer

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Re: Primary chain clearance
« Reply #13 on: 01.10. 2010 23:30 »
John,
thanks for those pictures. The engineer that did the work for me on mine also commented on the benefit of making a new basket and sprocket unit for any further builds, as the standard one is quite flimsy and in attaching it to a sprocket blank, pushes the clutch hub outboard requiring a sleeved nut to attach. Likewise as you mention the clutch hub limited what we could do as it didnt have much meat in it and was all alloy.
I sourced my clutch from a wrecker, seemed reasonable enough in cost, but was a bit of faffing about to get it in. We also used a bearing referred to in another post on this site, I'll source another friction plate next week which should have us running.
I have refitted my spacer plate between the engine and primary case and the chain clearance is much improved using a less distorted inner chain case.
Thanks
Tim
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Re: Primary chain clearance
« Reply #14 on: 01.10. 2010 23:45 »
Hi Tim
Did you machine away some of the back of the clutch basket before riviting it to the sprocket?
Cheers
John
1961 Super Rocket
1963 RGS (ongoing)