57 replies to this topic

[tiger99]

This has been debated here in the past week or two. Worth searching out the thread. I would provide a link but am only on my phone right now.

But the short answer is yes, they must be Deva bushes front and rear. Nothing else will do, especially the abominable floating bush from a certain incompetent parts supplier, which will do serious damage.

The Deva bushes have to be chilled in liquid nitrogen for fitting, so a very reliable person said. But just maybe CO2 would do, if the primary gear is heated in boiling water. I think that needs more discussion and a test.

[Orange-Phantom]

If floating bushes are so bad why do the likes of Swiftune and MED supply and use floating bushes in their race engines?

 

http://www.swiftune....ating-bush.aspx

 

http://www.med-engin...set-roller-type

[Dusky]

A) Race engines get pulled apart much more than standard engines (lots of the parts used on race engine's don't last long at all, even in a normal road car)
B) They aren't perfect at all ( look at my MED inlet fiasco) 

C) They need expesnive parts to make profit.

[Spider]

If floating bushes are so bad why do the likes of Swiftune and MED supply and use floating bushes in their race engines?

 

http://www.swiftune....ating-bush.aspx

 

http://www.med-engin...set-roller-type

 

I can't say what their collective thinking is, however, I'll say that it appears to me to be a lazy solution.

 

If it really was a decent, reliable solution, the factory would have done this back in the late 50's / early 60's where they did have primary gear issues back then, but of a different type. The materials used in these floating (and current range) of bushes are not some new age aerospace material, they have been around longer than the Mini.

 

The factory - rightly - found that with Bronze Bushes, they needed continual lubrication (Oil Fed), but the issues they had with this set up, was they couldn't keep Oil off the Clutch. If it were a simple matter of blocking off the Oil Feed and maybe increasing the clearance here a little, they would have done that.

 

Instead of that quick fix, they spent some years and considerable funds looking in to it before finally settling on the Deva Bush in about 1963 I think. They work as they have been there right up until the end of production, more or less unmodified, though about 66-ish, the front bush, while still of the same bearing material they metal backed only to help it with the high output engines that they were fitting by then.

 

The factory recommended method of fitting the proper bushes was with Dry Ice (though Nitrogen as tiger has suggested is OK too), then they need machining and so they are a muck around to replace. Most shops it seems don't know about the need to shrink them before fitting and then they see the need to machine them as more expensive work and I'm guessing that an alternative was looked for and this is what we now have, which IMO, is not suitable and found it many times over to be not suitable.

 

The evidence in this thread also shows that.

[Spider]

Sorry to bring up an old post here but I'm having this problem. I found this video on Youtube and I'm wondering if this solution will help with the  bushing issue or not.. 

 

and just to be clear, the best option for replacement is the Deva bushings front and rear? 

 

thanks

 

I wouldn't classify that type of issue as a Bushing Issue but a Flywheel Fit issue.

 

As a matter of course I always check the clearance between the flywheel and primary gear at a preliminary assembly stage, usually only an initial check is all that's needed, not every time the flywheel comes off as there's usually a reasonable clearance here, but if you don't check, how do we know?

 

Deva Bushes are all that I'll fit and I would recommend avoiding anything else.

[Spider]

Just a bit of a thread Revival here.

 

I've been asked a few time now how to Identify the Bronze type Bushes from the Proper Deva Bushes.

 

The Deva Material is quite dull in appearance.

 

Here's two Primary Gears side by side, the Bronze Bush is fitted to that on the Left and the Deva to that on the Right

 

Edited by Moke Spider, 14 December 2016 - 10:25 PM.

[Spider]

Thread revival !

I noted that I hadn't posted in this thread the info that's not in the UK Workshop Manuals regarding the replacement of the bushes, in particular the Deva bush. For your viewing pleasure;-

 

 

NOTE that this ONLY suits the factory bushes. The current replacements (that I don't recommend), I'd suggest seeking fitting advice from the supplier of those.

The dimensions shown in the lower photo is for all 1275 engines.

[Java_Green]

I am about to build a high torque engine and have come to the conclusion that I need to go for a A+ transfer gear transmission (A+ drop gears and transfer gear housing). Since I do not have these parts laying around, I need to buy new ones. The primary gear bronze bushing dilemma do make sense to me. So my question is, where do I find these parts and especially "proper" bushings?  

[JonnyAlpha]

Following this, as I have a second hand primary gear that needs to be re-bushed for my 1310 build. The only bushes we can get are the ones from MinSpares.

I asked what make they are and they would not disclose.

 

 

http://www.minispare...ic/DAM8889.aspx

 

and 

 

http://www.minispare...sic/22G109.aspx

 

If we use AC's clearances will we be OK?

 

AC - what lube do you recommend for the installation?

 

Seriously moke I have been fitting these since they were first introduced. I don't use the clearances recommended. I use my own.

Never a problem. The mpi engines do suffer with more bearing failures due in my view to very high final drive ratio employed together with strong average torque output. I have literally never had one back.

 

​​I machine my bushes to give a running clearance of  0.0045 to 0.005".  I have had engines run 85K miles with no issues.

 

 

The fault with the engine here uses original factory bearings. It is simply worn out.

 

 

Ac

[stoneface]

If you read this post it might answer a few question about your options.

 

https://www.theminif...-primary-gears/

 

There are many other posts discussing this issue.

[Pairaminis]

Does anyone (Moke Spider?) have an idea when the change from DEVA to brass bushings for the primary gear occurred?  I put my current 998 motor together about four years ago and don't recall what bushing might have been in my rear primary gear.  I'm wondering if that should now be a concern for me?

Jack

Edited by Pairaminis, 19 February 2022 - 05:50 PM.

[Spider]

Does anyone (Moke Spider?) have an idea when the change from DEVA to brass bushings for the primary gear occurred?  I put my current 998 motor together about four years ago and don't recall what bushing might have been in my rear primary gear.  I'm wondering if that should now be a concern for me?

Jack

 

In production, never, they Used Deva from 1963-ish to the end.

 

I think the Silicon Bronze bushes popped up around 2012-ish, maybe earlier.

[Pairaminis]

Thanks Mike Spider.  I didn't rebush my primary gear, so I guess I shouldn't have a"Silicon Bronze worry".  

Jack

Edited by Pairaminis, 20 February 2022 - 01:38 PM.