Hard vs Soft Isolastic Rubber (2009)

Problem resolved!

Just spoke to Angie Hemmings - the pre MkIII vernier conversion is £55 +VAT for the pair.

Bogus, Thanks for the clarification, I was planning to put a set on my bike but if the price had doubled - ,

I worked the price out to be a tad cheaper than the MkIII conversion (this includes all the rubbers, spacers, circlips & gaiters), so I'll be ordering mine later

The internet is amazing, and despite my crumudgeonly attitude that we have taken the mystery out of the world, I am so thankful for access to the information here. I could easily have spent hundreds of hours and God knows how much money and never figured out the information in this thread! Some mystery in the world is good, just not when it comes to figuring out problems with the bike!

rvich said:

The internet is amazing, and despite my crumudgeonly attitude that we have taken the mystery out of the world, I am so thankful for access to the information here. I could easily have spent hundreds of hours and God knows how much money and never figured out the information in this thread! Some mystery in the world is good, just not when it comes to figuring out problems with the bike!

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Agreed!

All the mods I'm incorporating in my rebuild are as a result of advice received here - granted, some of it is purely cross-referring to other knowledge bases, but the vast majority is down to the lessons learned by other forum members - absolutely priceless!

My rebuild actually started last weekend, so I may get a thread going...if I can find the time

B+Bogus said:

I worked the price out to be a tad cheaper than the MkIII conversion (this includes all the rubbers, spacers, circlips & gaiters), so I'll be ordering mine later

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B+Bogus, do you have a part number for the pre MkIII vernier conversion from Hemmings? I can only find the 06 7116 and 06 7117 parts listed. Maybe you just ask for the "Vernier Isolastic Adjusters". Also, I can’t seem to figure out which are the softer bushes or buffers. The only ones that are different are the '69 and '70 750's, although the MkIII's are only sold as an assembly (at least at Old Britts).

Thanks!

slick204 said:

Maybe you just ask for the "Vernier Isolastic Adjusters". Also, I can’t seem to figure out which are the softer bushes or buffers. The only ones that are different are the '69 and '70 750's, although the MkIII's are only sold as an assembly (at least at Old Britts).

Thanks!

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Ithink you'd be right - they don't appear to have a part number, and Hemmings knew exactly what I was talking about - i did qualify the question by asking for the pre-MkIII conversion.

The rubbers I'm ordering are 06.1126 (front) and 06.1227 (rear). I'll post my opinion on the rubber compound when they arrive.
The MkIII iso looks to be moulded as a single piece - some pics show a distinct mould line across all the bushes.

Things get much simpler if you go to the Norvil site and bring up the Isolastics page in the parts list. They have pictures of all of the parts and kits we're talking about. What Norvil calls the Isolastic Conversion kit and what Mick calls the MkIII Isolastic Conversion kit aren't the came thing. They don't list Mick's own vernier because they don't carry it. When you order Mick's from him it might be easiest to refer to them as his 'Patented Threaded Isolastic Collars', and leave 'MkIII Conversions' out.

Agreed - I had a good look at the Norvil site as this was what I intended buying until the MkIII rubber issue was highlighted.
The MkII rubbers definitely look different

Anyway, this is what I just ordered from Mick Hemmings:

06.1226 BUSH F/ENGINE MOUNTING 06.0421 £3.11 2 £6.22
06.1227 BUSH - REAR ENGINE MOUNTING £2.71 3 £8.13
06.1278 FRONT ISOLASTIC BUFFER (06.0428) £2.75 2 £5.50
06.1280 REAR ISOLASTIC BUFFER £2.50 2 £5.00
06.3718 FRONT ISO. MOUNTING GAITER £3.20 2 £6.40
06.3719 REAR ISO. MOUNTING GAITER £2.80 2 £5.60
06.3927 CIRCLIP - ISO. BUFFER £0.16 6 £0.96
06.3928 ENGINE MTG. SPACER TUBE (REAR) £2.68 2 £5.36
06.3960 ENGINE MTG. SPACER TUBE (FT) £3.51 1 £3.51
06.4748 ISO. PTFE WASHER (06.3556) (06.0578) £4.85 4 £19.40
No P/N VERNIER ADJUSTERS PRE MKIII £55.00 1 £55.00

Total £121.08

I just hope I got it right! :roll:

It's around a tenner cheaper than the Norvil MkIII conversion - I'll post a pic when the bits arrive if anyone's interested

After all of this we expect a full report...I know I will appreciate it as isolastic renewal is on my list.

Here is a list of what I got from OldBritts my old isolastics were in pretty poor shape.

2 - 06-1226 Front bush
1 - 06-1277 Front spacer tube
2 - 06-1278 Front buffer
3 - 06-1227 rear bush
2 - 06-1279 Rear spacertube
2 - 06-1280 rear buffer
8 - 06-3927 circlip

Cost me about $85 USD. Didn't get the PTFE washers. I'm going to use the nylon ones from Fair Spares or make some. I'm thinking about the Hemmings adjuster.

Dave
69 S project

B+Bogus said:

Anyway, this is what I just ordered from Mick Hemmings:

06.1226 BUSH F/ENGINE MOUNTING 06.0421 £3.11 2 £6.22
06.1227 BUSH - REAR ENGINE MOUNTING £2.71 3 £8.13
06.1278 FRONT ISOLASTIC BUFFER (06.0428) £2.75 2 £5.50
06.1280 REAR ISOLASTIC BUFFER £2.50 2 £5.00
06.3718 FRONT ISO. MOUNTING GAITER £3.20 2 £6.40
06.3719 REAR ISO. MOUNTING GAITER £2.80 2 £5.60
06.3927 CIRCLIP - ISO. BUFFER £0.16 6 £0.96
06.3928 ENGINE MTG. SPACER TUBE (REAR) £2.68 2 £5.36
06.3960 ENGINE MTG. SPACER TUBE (FT) £3.51 1 £3.51
06.4748 ISO. PTFE WASHER (06.3556) (06.0578) £4.85 4 £19.40
No P/N VERNIER ADJUSTERS PRE MKIII £55.00 1 £55.00

Total £121.08

I just hope I got it right! :roll:

It's around a tenner cheaper than the Norvil MkIII conversion - I'll post a pic when the bits arrive if anyone's interested

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I'm interested! Thanks for posting the complete list. My gearbox is on a UPS truck back from CNW and I want to do the rear iso while it's apart.
Now if I could just figure out how to make an international call.....

Thanks again.

This is how it worked for me for a 69 setup. First picture is old iso as they came out of the bike, I have to believe they were original because of the shape and I got the bike after only 1 year of being new. Top shows rear isos, with 3 molded bushes, 2 spacers and 2 buffers (the 2 donuts alone). The 2 buffers were loose in the tube. Lower shows front iso with 2 molded bushes, one spacer and 2 buffers (the 2 donuts alone), they also were loose in the tubes.



Next picture shows new isos from OldBritts, top is front with left to right, 06-1226 molded bush, 06-1277 spacer with 2 06-1278 buffers and 4 06-3927 circlips to hold the buffers unlike the original. Bottom is left to right 06-1227 molded bush, 06-1279 spacer with 06-1280 buffer and 2 circlips as above,another 061226 molded bush, another 06-1279 spacer with buffer and circlips as before, and finally another 06-1227 molded bush.



The big difference with the new setup is that the buffers are retained on the spacers with the circlips unlike the old setup which had the buffers loose in the tubes. I don't know how they were effective if they were just left wandering around between the buffers??? The original molded bushes seemed also to be molded to the front iso tube and the rear engine cradle bush tube. Maybe they were just there so long they got stuck there by force of habit.

I hope I got the numbers right.

Dave
Remember, if they can't find you handsome, maybe they can find you handy.
69 S Project

Dog, how are you reassembling the rear iso? Are you doing it "in frame" or do you have the swingarm and everything off?
remember to use silicone grease and lube the cradle and all rubbers good!

Dave, There are a couple things you may want to think about doing when you assemble the iso's. The first is to grease the rear stud and front bolt lightly to keep it from sticking, (rusting), to the metal collars on the buffers and bushes. People have been known to have to saw the ends of the stud off to get the cradle out of the frame. The second is to get generous with silicone grease on the bush's. As you found out, they weld themselves to the inside of the tubes. The inside of the tube has to be as clean and smooth as you can get it. It helps if and when you ever have to take it apart and makes setting up the iso's easier.

i'm a way from installing the isos. Believe me the bolts and the inside of the iso tubes will be lubed enough for my lifetime, I couldn't believe how bad they were when I took them apart. I'll be setting up the isos without the motor in the frame, so I can do it all on the bench. Should make life easier. Hope to get this thing together by spring, I haven't got too much longer.

Dave

It looks a lot like DogT has the same bits that I ordered :mrgreen:
I faxed the order yesterday afternoon and the bits arrived today. - Impressed!



The verniers replace the left hand shim assembly whilst retaining the original right hand in situ, so if (like me) the whole thing has been pulled apart, there still may be a bit of shimming to do as a one-off to get the motor centralised before final adjustments are made.
I did get the gaiters and circlips, but just left them off the photo.



the grub screw has a nylon pad embedded in the end, and Mick's advice is not to overtighten.

The bushes are definitely as soft as the originals, so buy with confidence



All in all, a very satisfied customer. The rear bushes are now more expensive than I listed at £4.95 vs £2.71 (Andover price rise), but they didn't hit me with the difference.

Performance report to follow within the next 18 months

On the subject of Rubber, My little friend Dennis Lawton.Lawton Sales Weston Nr Crewe makes these rubber Isolastic's. I have collected the compound which is of a specified SHORE hardness. Problem is after molding they continue to CURE. ie get harder . Heat . TIME and to a lesser degree LIGHT continues the curing action. Having Seen my pal Colin's Harley 883 sportster "Shaking" i would have a guess and say the Norton set up is quite firm compared to. SO ..as your New Iso are on the stores shelf...they are getting Cured, Harder :?: ....Dennis also produce's Spitefire[plane] rubber parts...these are kept is black bags... Den keep's the rubber compound is freezers to hold back the CURING process...Make's you think what's happening on a hot summers day :!: :?:

john robert bould said:

On the subject of Rubber, My little friend Dennis Lawton.Lawton Sales Weston Nr Crewe makes these rubber Isolastic's. I have collected the compound which is of a specified SHORE hardness. Problem is after molding they continue to CURE. ie get harder . Heat . TIME and to a lesser degree LIGHT continues the curing action. Having Seen my pal Colin's Harley 883 sportster "Shaking" i would have a guess and say the Norton set up is quite firm compared to. SO ..as your New Iso are on the stores shelf...they are getting Cured, Harder :?: ....Dennis also produce's Spitefire[plane] rubber parts...these are kept is black bags... Den keep's the rubber compound is freezers to hold back the CURING process...Make's you think what's happening on a hot summers day :!: :?:

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An interesting point, and well made - It's true that aircraft rubber components have a fixed life based on the cure date. after this they're scrapped - even if they've never been fitted.
From recollection it's maybe up to ten years, but that's also how long ago since my knowledge was current
The same is also true of rubber-sheathed hydraulic hoses on bikes - they have a finite life.

highdesert said:

Good questions, Stephen!
My 750's always transmitted less vibration with the same iso clearance settings than my 850s.
The only possible reason I can think of is that the 850's have heavier pistons.
In theory, it should not make any difference if the iso rubber's end caps have shims or adjustable threaded adjusters.
In reality, I don't know because I converted my 73 to threaded adjusters years ago and can't remember.

I do know that put in all new rubber donuts about eight years ago and the bike with same iso clearances does indeed vibrate more so.
I suspect I was sold the "harder" donuts.
If I was you, I would call old britts and mick hemmings and ask them specifically if the sets the sell now are considered "soft".
I would want the soft ones, if that is an option, and I will check on this next time I replace mine in a few years.

I can't see why there would be rubbers specific for a 750 and then an 850 because there was no change in the cradle specs they go in to, to my memory.

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Eight years ago.....maby time you changed them :?: