12 replies to this topic

[MaximMini]

Hi Everyone,

 

I have kind of re-engineered the top hat bushes for the primary gears with the original manufacturer DEVA (part of Federal Mogul) here in Germany over the last month. And while this started as a engineering exercise for me, I'm wondering if there is a general interest in making these bushes available again.

 

While the bushes will be of the same kind of sintered bronze material, the material has been updated according to the latest technology at DEVA. Using the latest material technology and doing rather small batches, the main advantages over the original bushes are:

 

- The bushes will come heat treated and there will be no need for any further treatment (submerging in hot oil or else) after final machining.

- The bushes will be made to OD tolerances that allow pressing in with 'standard' equipment without nitrogen cooling or else.

- The bushes can be machined oversize in ID and/or OD to compensate for wear / machining on the primary gear bore and/or crankshaft.

 

Of course all this does not come without it's drawbacks which here is the costs that very much depend on the number of bushes to be made (per batch). A first calculation for some (approx. 10) prototypes resulted in costs of just short of 100 Euro per piece but could be brought down to approx. 50 Euro when doing 100 pieces. This is quite expensive compared to the current offerings on the market but from my point of view still fits in engine rebuilding budget.

 

Last but not least I would like to make absolutely clear that I don't question the current available solutions and what all the experienced engine builders are doing to make the bushes reliable. It all started as an engineering exercise and can well and as such after making a small batch for my friends and myself.

 

 

Cheers from the Pied Piper's Town

 

 

[nicklouse]

Have a chat with AC Dodd as he is doing the same. You might be able to work together on the base material costs.

[stoneface]

Are those prices for a finished machined part?

[MaximMini]

Yes, these are the expected costs for machined bush ready to be pressed in the primary gear. A final machining will then still be required to match the individual OD of the crankshaft.

[stoneface]

Thank you, and is the material the same as the original Deva metal or an alternative material?

[Spider]

It's always nice to see parts that have been un-available, become available again, however here;-

 

 

- The bushes will be made to OD tolerances that allow pressing in with 'standard' equipment without nitrogen cooling or else.

 

I don't know what the material is, but I would tend to think that if the bushes are hard enough to withstand this, then I'd be worried that they'd be hard enough to wear and possibly damage the crank.

 

I and many other have tried the bushes currently on offer, which are not to OEM standards and paid the price for doing so. I gotta say, I'm totally loathed to go down that road again, unless it's tried and extensively tested. I've looked in to and been offered many materials for this application and while they all have said " it'll work good as Deva " none could say with any certainty that it won't cause damage, like the original soft Deva bushes. The alloy mix of the Deva series of materials is patented so I'm unsure just how another firm can legally manufacture the same material.

 

Together with another member on the forum here, we have had a batch of Deva slugs made by Deva to the same grade as that used by BMC / Leyland / Rover. My time has been soaked up elsewhere of late, but I'll have most of these machined up to OEM Drawings. I'll hold a few of these back for bushes that need to be custom made to suit jobs that are outside of spec.

 

AC also contacted me a short while ago, with an offer of 'Deva like' material, which again, I don't know anything about other that it's not Deva.
 

[ACDodd]

Just to be clear My material is made by Deva to the original material spec. It’s a heavily graphite loaded sintered bronze. I have the hot pressed version as the original factory spec calls for 2 different specs depending on whether it’s cold or hot pressed.

I also use a leaded bronze for the front bushing which I have had good success with.


For those that want deva top hat bushes I machine these to order so that I can size appropriately to take into account wear etc. these using the same original press fits.



Ac

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Edited by ACDodd, 14 November 2021 - 11:04 PM.

[Spider]

Just to be clear My material is made by Deva to the original material spec.

For those that want deva top hat bushes I machine these to order so that I can size appropriately to take into account wear etc. these using the same original press fits.

 

Ah, OK, cheers, I stand corrected and sorry a bit confused here too. The OEM Bushes were a shrink fit only, however that aside, I was always of the impression that you were happy with the current silicon-bronze bushes on offer? Or did I misunderstand this ??

[ACDodd]

To clarify, I use the leaded bronze on the front bush only.

Not had an issue yet, been fitting for 3 years.

The rear top hat bushes I have been using the minispares stock replacement, not had an issue.

The DEVA metal here is so I can make the rear top hat bush for any custom application including the original small tail cranks from the 850 engines. Getting a few requests now.

I have never shrunk fitted an original deva bush top hat bushing I have never found it necessary.

Ac

[Spider]

Thanks for clarifying that.

I've never been able to press the Deva Bushes at room temperatures, that was why I looked up the factory instructions long ago. If you are able to press fit your bushes at room temperature, then I know from experience, they are not the correct grade of material and likely too hard.

[ACDodd]

Maximmini, you will be hard pressed to find load of customers, I would not lay out load of money of pre made bushings, I plan to use the material I have had manufactured to be able to make custom bushes when the need arises. The top hats available from minispares work fine with the correct clearances and pre lube, but if you use the original factory clearances you will have problems.

Ac

Edited by ACDodd, 15 November 2021 - 06:34 PM.

[MaximMini]

My primary interest in this matter is not commercial. I do run an engineering side business which allows me to deal with DEVA but I'm not in the position to do mass real condition testing or handle any warranty issues a commercial trade of the bushes may result in. If anyone would be interested to cooperate with me to make the bushes widely available I would be pleased of course.

 

I appreciate all the thoughts that you have shared and will approach the DEVA application specialist again with a list of questions I'm currently cumulating.

[stoneface]

Hi MaximMini, I’m the other forum member who worked with Spider to have a batch of blanks made, so I know the price we paid which is why I was interested and asked if yours were fully machined and original Deva metal or an alternative?

 

Most people seem to accept the currently available silicon-bronze version or are just unaware that the material changed. Personally, I’m not a fan, and imo the fact AC had to find a work-around to use them, but they are being sold and advertised with the original tolerances, shows how little testing was done by whoever decided to introduce a different material for these parts.

 

AC says the numbers are not big and he’s probably right. I wouldn’t know as I’m not in the industry and my own requirement for genuine parts was a personal one not commercial. Others are far better situated, have a greater need, and well regarded in the industry to do this better than me.

 

Also, the fact that the only contributors to this topic so far are those who have already sourced original parts must count for something as to the demand.

 

Having said the above, don't stop if you wish to pursue your project. Without people like us giving up our time and finances, the ability to have an alternative option would not be there. Just don't expect to make a fortune and prepare to make a loss. If nothing else comes of it, at least you now know there are people out there with genuine parts and material already.

 

With regards to press or freeze fitting of Deva bushes, I'm firmly in the freeze fitting camp.