57 replies to this topic

[pete l]

http://www.somerford...oducts_id=12388

[pete l]

what about one of these 

 

http://www.minispare...px|Back to shop

[pete l]

Or one of these ?

 

http://www.minispare...|Back to search

[pete l]

Adrian, I see you liked my post about the bush, What's your views on the floating one please.

 

Pete.

 

 

Forget that, there is no floating bush for A+ 1275 engines

Edited by pete l, 23 May 2016 - 11:48 AM.

[pete l]

Moke spider

http://www.theminifo...k/#entry3388431

Some links for you.

[ACDodd]

I fit bushes for other professional engine builders. I don't have these problems with the bushes supplied by minispares. Correct line boring and sizing is only part of the solution. You MUST use the appropriate lube when installing a freshly bushed gear. Engine oil is not sufficient.

Ac

Edited by ACDodd, 23 May 2016 - 09:27 PM.

[pete l]

Ok, but because it's not a deva bush, how long will yours last ?

Do you keep them in stock ?

And the most important question, how much to redo a primary gear ?

[Spider]

pete, as far as I can determine, there's only one or maybe two manufacturers of these bushes these days. They are all bronze based and they all very much have the potential to pick up on the crank and do the damage as seen here. Thanks for all the links too.

 

AC - while you may not have yet seen any damage, I'm sure they will start to come in as time goes by. Respectfully, in regards to special fitting methods and lubricants, that's all good and well, however the suppliers should point out that these are a different bush to OEM, provide the fitting instructions and recommend the correct lubricant. I have looked at the Mini Spares listing, and with the clearances that's been recommended there, on the lower end, these bushes will grab on to the crank, no two ways about it.

 

The factory did look at going down this route, with similar bushes, however, in their wisdom, they also determined that these bushes required an oil feed. Our local bearing designers (who I use from time to time), are looking in to this as well on my behalf and they have at this early stage suggested that this material cannot be run in this way without an oil feed and have also said that this is not the wisest material choice.

 

Also, how is it that for the past 30+ years that many of us have run DEVA bushes, that while we've all seen worn bushes, I am yet to see a damaged crank from them.

 

By the way, the example I put up here failed in about 4000 km since last inspected and did around 20 000 km in total since fitting. None of these were 'city' kms where there would be frequent clutch use.

 

EDIT:>  Seems we are starting to see a common theme here

 

http://www.theminifo...k/#entry3388431

 

(Thanks Pete for linking these)

 

I have another damaged Primary Gear in the workshop from a couple of years back. In that case, the bush grabbed the crank after doing a reputed 5000 odd km and then spin in the gear itself. I'll put some photos up later.

 

Talking around the traps, this issue is far more common that is realised as it's not often talked about and put down as 'bad luck'.

[pete l]

So is there a solution out there ?

Buy a genuine second hand unit ?

[ACDodd]

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

Edited by ACDodd, 23 May 2016 - 09:35 PM.

[Spider]

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.

Ac

 

Fair enough AC and I'm happy that you've so far had no issues.

 

I won't be using any Bronze based bushes.

 

I've not needed to fit these bushes myself as a replacement as I've had a stash of Deva Bushes, but now I've run out of these and with this one that's here for repair, I'll likely be doing Deva ones.

 

One other factor maybe to ponder, and that is if a bush should fail or grab (what ever it be made from), wouldn't it be best to minimise any subsequent damage?

 

EDIT:< AC, I respect completely that you've done your own R & D on these and how to use them, from which you are deriving a living from, so I won't ask how you are doing them, however, can you shed some light on how long these bronze based bushes have been about? >

Edited by Moke Spider, 23 May 2016 - 09:36 PM.

[ACDodd]

Hmmm how long, I would have said 6 or 7 years.

 

AC

[ACDodd]

Just about all failure where new bushes are concerned are due to little or the wrong type of lubrication in initial install, or the wrong clearances employed. In these cases failure in pretty quick after the new engine is first run, usually shows up in the first 2000miles.

 

The new bearings are a harder material and do not hold lubrication like the originals. Hence the clearances need to be bigger in my view to aid success.

 

In the MPI engine Failure starts with the front bush it gets hot and spins in the gear. It wears, the clearance increases and the rear bush starts to run out of alignment. At some point the front lip cannot stand the out of alignment running and it breaks away. 

 

I also agree this is a common issue.

 

 

​AC

Edited by ACDodd, 23 May 2016 - 09:48 PM.

[pete l]

Correct me if I'm wrong, but the only time this primary gear is spinning on its bushes is when your foot is on the clutch ? In which case how can a more powerful mpi engine do more damage than a standard one ?

[Spider]

​​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

 

 

Purely as an example of the Deva bushes, one of the first I did was in 1984 or 85 and has done over 300 000 km. At the time of a clutch replacement about a year ago on that car, the primary gear was pulled and while there was some wear in it, it was still well within spec. It was oiled and re-fitted. Car is a 1275 engined Moke and not always driven sedately, as the owner's son, who drives it daily, does have a heavy right foot and a lazy left,,,,

 

I really haven't yet seen an issue with the Deva bushes that warrants going to a harder or different material replacement for normal to hard road use. Maybe in competition, though I really can't see the absolute need here.