I am putting a Triumph single chain 4 spring clutch together for my Gold star project bike. The parts i have don't match properly meaning there is to large clearance in the roller bearing.
The chainwheel i have had new for many year has a mark " RS-038 " inside. The inner dia is in metric 47,71mm The outer dia on the adaptor is in metric 34,92mm the rollers are 6,35 x 6,35 This gives a clearance of 0,09mm
In inches The inner dia is in inches 1.8783427 The outer dia on the adapter is in inches 1.3748004 the rollers are 0,25 x 0,25 This gives a clearance of 0,0324 in inches.
I have been told here that it should be a clearance of 0.01 mm in inches 0.0003937. what is the proper clearance?
I could try an find oversize rollers BUT what is the correct inner dia and outer dia for this clutch in the first place? Do I have a chain wheel or adaptor with wrong diameter???
Please enlighten me. PS i have checked it all in metric and converted it to inches online.
I checked an old chainhwwel and it was a lot tighter then my new described above. please tell me the correct chainwheel inner dia and proper clearance then I'll decide if to buy oversize rollers or a new chainwheel.
Morgan ... You need to order up the correct roller bearings for your clutch. if you fit the 0.25" x 0.25" rollers there won't be enough roller end play and the hub will lock up. I vagerly remember the correct roller size to be 0.25" diameter and 0.235" long. I can measure if needed as I have a 4 spring on the shelf.
Another thing ... Be sure to use the correct nut, spacer washer and tab lock washer as BSA used with the 4 spring unit. I reco fitting a new mainshaft key. Hopefully your mainshaft keyway is usable. Tighten the nut with a impact wrench! Do Not use the POS nut fitted with a 6 spring clutch. I have the correct part numbers if you don't. BTW, all of the correct parts are shown in the late model A10 parts book. This doesn't apply to you, but the nut and spacer washer made for fitting the 4 spring works nicely to fit a belt drive primary clutch on a BSA pre unit.
I highly recomend fitting a Tony Hayward clutch adapter with the large diameter thrust face and bronze thrust washer. This will eliminate the issue of the OEM BSA design adapter with the smaller diameter adapter thrust face from wearing into the back of the chainwheel and it will minimize the chain wheel 'wobble'. Hayward normally supplies this adapter to fit his 3 spring design clutches to pre unit BSAs. A nice piece. I've not tried it, but I see no reason when using the Hayward adapter you can't make a early 4 spring 'rigid' vs 'wobble' when engaged as later BSA/Tri 3 spring clutches. You would only need to grind off the tabs on the inner splined hub. hmmm
Be sure to check your sprocket/chain alignment with a straight edge when fitting the 4 spring clutch. This is easily done 'dry fit' with the inner primary case off and out of the way. If you are fitting a OEM chainwheel with the 'dished' back face the alignment should be close to OK. However when fitting the typical 'flat back' repop chainwheel, you will prolly need to shim out the engine sprocket 100 to 160 thou.
Dave beat me to it! Anyway I measured my clutch rollers and they are 0.25" dia by 0.23 width. As Dave says the 0.25 rollers will bind (its a common mistake to assume that standard 0.25" by 0.25" rollers will work).
My unit engine clutch basket measures 1.86" inside the race. Although not pre-unit, I wouldn't have thought that it would be different.
Dave and britbodger thanks, I have already bought an adapter. it is nor a Tony H type It seams i need to catch up with some knowledge. still what is an acceptable clearance for the rollers? i have now a clearance of 0,0324 in inches on the rollers.
Bummer.. i have 3 sets of rollers, two are 0,25x0,25" and one are 0,25x0,23" however since my chainwheel has wrong inner size and so on maybe best idea is to buy a complete clutch instead and sell the parts i have one by one.
Dave do you have a photo of a Tony H adapter? or what is the meassurements of it?
Morgan .. I hope this finds you well. I took some pictures of a Tony Hayward clutch adapter and made some measurements for you of a pre unit 4 spring clutch.
20 each rollers: 0.247" x 0.233 long adapter bearing race OD: 1.3725" chain wheel race ID: 1.869" bearing clearance: ~ 0.002"
As I've mentioned the nicely made Hayward adapters are made to fit the BSA 3 spring design clutch center to the Hayward belt drive when fitted to a pre unit BSA tranny. The thrust face uses a bronze thrust washer and the thrust face OD is 2.672". Unlike the OEM BSA design 4 spring adapter it won't wear into the chain wheel face, pushing out the bearing race. Also the Hayward adapter splines will show no wear unlike the OEM BSA (repop?) adapters. Questions?
Tony Hayward 28 Kelsterton Road Conan's Quay, Deeside Flintshire CH5 4BJ England
011 44 1244 830 776
I've posted you the photos of the adapter in a Email as I don't have capabilities to send them to bb.com
Thanks Dave, That was good info. all measurements seams to be different depending whos parts we check.
I need to think this over and maybe order all parts from one source. So should the bearing clearance be 0.002 inch? or what is the ultimate clearance to go for. Anyone knows the factory specs? John H do you know?
Hello Morgan ... You doubt the measurements I've given you of known, not a 'maybe', pre unit 4 spring clutch and adapter parts? hmmm. The measurements were carefully made with my digital calipher. I guess I could use my micrometers and give you values in tenths, but why?
Bear in mind except for Goldies fitted with belt drives or the Pearson clutch, the 4 spring unit is by far the most commonly used world wide. It's certainly not a unproven 'modification'
The 4 spring was fitted by BSA on the '62 and '63 GSs and the A10s. Strangely the notorious 'slip and drag' POS 6 spring unit wasn't replaced years earlier.
Dave I do not doubt your measurements, no way, just see that i get various measurements from separate sources. I need to decide weather to keep the adapter i just bought and wonder if i get me a new chain wheel ask my self will it fit my adapter and how about the rollers. yours are 0.247" mine are 0.25 what is really right??? inner dimension rollers and chainwheel must cooperate. Since i don't know what is right from the factory i'm asking that question. sure i have been thinking of a person clutch or asking SRM or any to provide mw with a complete 4-spring. Had one for 17 years on a M21 which worked perfect and on a GS that i sold back in 1996 (fitted in 1990) but i forgotten about the measurements. So now when trying to put one together with pieces i had on the shelf i realize something was wrong. It would be good to know how much clearance is best for a 4 spring for the reason of knowledge. Right now i need to get me a clutch as next step is to align the primary sprockets/chain. 20 years ago i had this in my head but now i have forgotten as i havent done this type of work...
measurements in thents is not nessesary but i only have metric measurements tools and not inches tools for thousands of inches that is why i convert.
Dave my 1957 M21 had a 4 spring clutch from the factory. the reason for that was it was an ex AA patrol bike with a radio instead of a pillion so it had both alternator and generator. Alternator supported the radio equipment. therefor the triumph clutch on that early mod.
Well I am open for suggestions on someone who can deliver a complete high quality Triumph 4 spring clutch for a BSA pre-unit S/A gearbox.
Dave and rest of you.. Received a complete 4 spring clutch from SRM today with same adaptor above and 0.002 clearance. Have tighten it a bit and it feels real good when testing. I'm glad I spent the money.
I am having some clutch issues myself as I am fitting a 4 spring Triumph to an A-10 . I have the adaptor that I am told is for a GS and I assumed it would translate to an A-10 but now I am told the taper is different and I have found the offset to be substantially different . Is there an adaptor specifically for the A-10?
This adaptor is for A10 as SRM are working with Twins only I have no clue what my gearbox is it is a S/A box. Ask SRM about it. They have a big batch made. Maybe some of the US importers stock them. I now they were out of stock and is freshly made.. I also heard that there might be two kindes of tapered shafts by MCA Aston in UK. Sorry that I cannot give you more specific info but I do know that Tony Haywood mentioned by Dave above gets them from SRM
Bonzo---if all else fails contact Draganfly or C&D Autos or Lightning Spares in UK and ask for a center for a 1961 A10. Late 1960 A10s and certainly 1961 and the few A10s made in 1962 were fitted with the 4 spring Triumph clutch as standard from the factory. Used to have a 1961 A10 in UK in the 1960s so it is true from the horses mouth. Neigh!! Neigh!!!!!!
thanks for the heads up . I will contact them asap. TM , I took a look at the parts book and it appears from the drawings that the center hub on the 4 spring A-10 still used the twin ball bearing setup rather than the rollers and thrust washer . The rollers and thrust washer are what I am looking for for more stability . I just checked prices for new steel and fibre plates for the 6 spring as a backup plan ....YIKES... now I really wanna find this adaptor .
BTW , does anyone have contact info for tony haywood?
Well, I need to bring this up again... I may have not been paying enough attention? I really am a noob when it comes to the clutch conversions...
BTW, my '63 Super Rocket, of which I was the second owner, had a 6 spring clutch assembly in place, not a 4 spring. Only had 4700 miles on the clock, when purchased...
I bought a box 'o triumph clutches, 4 chain wheels, two of 'em without the band around the basket, 5 hubs, one hat, and one clutch center, with enough plates to make up about 1-3/4 sets, ONE stud, 5 springs, 1 spring cup, and 1 spring nut. One of the hubs is a hollow thing, and according to the parts pic that Morgan put up, is a correct BSA unit, the other 4 having the cush drive rubbers inside?
Is there a problem using both cush drive set-ups together? The A10 engine cush, and the clutch cush?
Can the outer bearing race be pressed out, and repressed into another chain wheel? One of the wheels with a band, seems to not have the outer race in place... Is there a problem with TIG spot welding a race into place?
Is anyone selling, or installing, new bands?
Dave, the original dished chain wheels.... How much of a dish? Are the "flat back repops" truely flat all the way across? All 4 of mine seem to be mostly flat backed, but around the area where the center hub flange may ride the wheel, there is a slight recess, mebbe .020"+ deep???
Other than needing to elongate the chain, and having to find an adaptor, is there a benifit to fitting A65 3 row chain clutch set-ups? Does anyone make the adaptor center hub for A10 use?
Earl Bowlby, the hillclimber, told me he had better clutch action out of a 3 spring hub, than a 4 spring hub.
He also told me, on the A10 4 spring set-up, with that hollow hub, and the BSA hat, he had several instances where the assembly, had broken the push rod, because of the hat's push rod end cup, and the ability of the spring cups to move about more than the cush hub would've allowed.
One of his fixes, was to use triumph hats, with the adjuster in the center. And it was better to use the large adjuster hats. He eventually developed a way to brase a nut onto the small adjuster hats, to accept a large adjuster.
He also told me he took a hub, milled the tits off, took an extra clutch fiber plate, sanded down one side to metal, put that fiber in first, metal side to the basket, and got another clutch surface to enguage.
Yes I've heard about belt drives, and ex500 clutch systems adapted into use. All of 'em expensive. Badly. Trying to see other ways to get good clutches into these three A10's I'm building....
Dave, if you have the parts, or the part numbers [ anyone else? ], I'd like to know about the correct nuts, washers, and anything else I need, to properly attach the clutch hub to the center, using the cush hubs? Which may be triumph hubs?
I have no authority about the trans shaft's tapers, not even trying to see if my GS's STD trans is different or not from my A10's... Never heard of them being different before, either.