The Marston Sunbeam Club & Register Forum

General Category => Technical Discussion Forum => Topic started by: ChrisF on March 15, 2026, 07:45:45 PM

Title: 1934 Model 8 Cush-Drive Spring
Post by: ChrisF on March 15, 2026, 07:45:45 PM
Hello. Can you tell me if the attached photo looks like a cush-drive spring for a 1934 Model 8, as I'm not so sure? It will take a lot of compressing to get the nut on & I'm sure Rick, in a previous post regarding these springs, said it should be reasonably easy. The spring measures: ID=47.8mm, OD=69mm, length=35.8mm. Cheers Chris.
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: Thomas on March 16, 2026, 08:07:19 AM
Hi Chris, I don't have a Model 8 and I am not sure about the difference between ,,a lot of compressing" and ,,reasonably easy". But as long as you can fit the cush drive by hand it'll do. Watching your pic it sees to me that the sprocket is too close to the inner chain case. Is the chain running freely?
Cheers, Thomas
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: ChrisF on March 16, 2026, 05:17:08 PM
Thomas, Thank you for your reply. I think the shadow in my photo makes it look like the sprocket is close to the case but with the chain on I have a reasonably good gap. As for the spring , I can't compress it enough by hand to start the nut, but I could if I adapted a puller, which is what makes me think it's the wrong one. Cheddar Autojumble is in a couple of weeks time, I'll have a rummage.
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: Thomas on March 16, 2026, 06:42:57 PM
Hi Chris, attached are three pics of my situation. It seems that your spring has more windings than mine and therefore a greater length along the shaft. That might make it so difficult for you. I am now of no help anymore because I don't know the correct length for the Model  8. BTW: The teeth look pretty worn to me. I'd consider getting or making a new sprocket. I've had to do that before.
Cheers, Thomas
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: ChrisF on March 16, 2026, 07:06:53 PM
Thanks for your help Thomas.
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: singleminded on March 18, 2026, 03:24:09 PM
https://www.sunbeamland.com/partslist/
Take a look here to see if it is the same as something else ..looks like it could be a common part.
John
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: ChrisF on March 18, 2026, 06:58:29 PM
Thanks John, I'll give it a go!
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: ChrisF on April 19, 2026, 05:56:18 PM
Got it! I thought the spring may be too long but I'm using the wrong nut. I was using a half nut but was informed by a very helpful chap, with a stall at the Cheddar Autojumble, that it needs to be shaped to fit through the big washer & draw the spring down without me needing to compress it first. A Triumph 5/8 x 20TPI alternator nut seems to do the trick.
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: singleminded on April 20, 2026, 03:42:34 PM
Was that David Ormond.
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: ChrisF on April 21, 2026, 05:34:41 PM
Sorry, I didn't get his name.
Title: Re: 1934 Model 8 Cush-Drive Spring
Post by: wessex_man on April 21, 2026, 07:15:34 PM
Gland you got sorted Chris. Yes thats the basis of the nut I described to you at Chedder. Ment to post this earlier but forgot. Very roached 350 shock  about your time period showing the nut.
(https://i.postimg.cc/CM7mC8Y4/beam-shocksamp.jpg) (https://postimg.cc/kDVQqB2V)