Tailshaft bush

Post by **les** » Sun Sep 07, 2008 6:26 pm

If you are tempted to replace the tailshaft bush in the gearbox, think twice, apart from the difficulty extracting and putting back the said bush, when it is finally reamed to accept the propshaft end, most of the bronze in the bush is removed leaving its steel back exposed. I've fitted 3 bushes so far, ( £9 each) thinking I had a bad one, but it seems they are all the same. I've refitted the original, at least it has a bronze surface. It all goes to prove it's not only panels.

Post by **bmcecosse** » Sun Sep 07, 2008 6:38 pm

Wow - so, how much reaming did it need ?

Post by **les** » Sun Sep 07, 2008 6:50 pm

Fair amount, they are extremely tight and tend to close up when in place, in fact before fitting I tried the prop end and it was tight then. The amount of bronze in the bush is minimal so there is little hope of much remaining. It's a split bush and I've even tried running a hacksaw down one to let it close more, but it still broke through when reamed, I widened one too much and when assembled the reamer spun it in the housing.

Post by **bmcecosse** » Sun Sep 07, 2008 6:55 pm

Hmmm - you would think it would be made from bronze tube - rather than thin bronze sleeve in steel! In fact - nylatron may be the way to go! Could even have a light reverse scroll machined in it to return any escaping oil. Don't suppose you care to mention the supplier of this piece of $£&* ?

edit by A

Post by **les** » Sun Sep 07, 2008 7:16 pm

I don't want to upset the bosses here! The strange thing is it has a 2A number which looks like some original stock number, although the one I originally removed had a icon on it, maybe vandervel. I think I will get some more details from the supplier as I'm not really happy about all this.

Post by **bigginger** » Sun Sep 07, 2008 7:32 pm

Nobody upset - just a bit daft to leave 'swear words' up, even if they are cunningly disguised with $ signs etc

Post by **bmcecosse** » Mon Sep 08, 2008 5:28 am

It was hardly a 'swear' word Andrew - but the idea still shows through after your 'modding'. I thought Mods were supposed to PM anyone whose thread they found a need to Mod ?
les - it's only Mods who can't name and shame - stating the supplier of an obviously inadequate part is fine - and should be done to protect others who may be considering buying that part.

Post by **rayofleamington** » Tue Sep 09, 2008 12:03 am

I've not had to do this job for 10 years but on the 2 or 3 I had done it was no problem at all.
The bush was sliding fit to the prop when not assembled and quite a large (1mm?) interference when assembled. It was not a 30 second job to fit due to the interference with the gearbox housing.
After reaming, the radiussed groove in the bush was still quite deep and therefore tonnes of brass left...

If the latest ones are "no brass left in places" when reamed, you are legally entitled to a full refund from supplier (Sale of goods and services Act) as they are not fit for purpose.
Sadly you are unlikely to get a refund for the wasted machining time, but at least the supplier will know for definate that he is selling parts that should not be sold at all.

Also it's worth to copy the complaint about any consequential losses due to clearly unfit parts to Ray Newell and the working(?) group.

Post by **les** » Tue Sep 09, 2008 7:52 pm

Thanks for that, it's food for thought. The supplier is a 90 mile round trip from me but maybe I could send them back by post with a covering letter. I explained the initial problem last time I went there, although it was only to a young lad, and then just bought another, but it seems pointless buying more, perhaps I should jump up and down more!

Post by **bmcecosse** » Tue Sep 09, 2008 8:41 pm

As I suggested earlier -perhaps this would be an ideal place for a Nylatron replacement. Should be inexpensive to run up for anyone with a handy lathe ?

Post by **les** » Tue Sep 09, 2008 9:06 pm

I think the material needs a steel back, as the bush needs to be tight in the housing, I'm not familiar with this nylatron but suspect it would collapse whilst pulling into place.--- Nylon?

Post by **bmcecosse** » Wed Sep 10, 2008 1:36 pm

It's a filled nylon material - very robust and used in industry, and self lubricating depending on the 'filling'. It would need to be made a snug fit in the housing - and then pressed home with a smear of loctite. If made precisely it may not need reaming - but more likely it would need a slight 'ream'. Point is - it would be solid tube of material - not brass/bronze inside steel sleeve etc. Would be far less expensive to make i'm sure.

Post by **rayofleamington** » Fri Sep 12, 2008 8:56 pm

A plastic bush is unliely to work well and will probably come loose after a few thermal cycles anyway.
Some of the bushes we use at work are teflon rich plastic material inside steel sleeves, which work well as the steel ring allows a good tight fit. However this won't be much use on the tailshaft as it needs the groove to maintain oil circulation over a large surface area.

Post by **bmcecosse** » Sat Sep 13, 2008 5:28 am

Dunno Ray - that sort of bush is used quite a bit in industry. Good loctite would hold it in just as well as the steel backed bush. The gearbox doesn't get all that hot after all.

Post by **rayofleamington** » Sat Sep 13, 2008 1:48 pm

that sort of bush is used quite a bit in industry.

any decent engineer will tell you that you need to check the application before assuming something you've 'seen elsewhere' will work.

The gearbox doesn't get all that hot after all.

I wish I had a set of Minor disks for every time I've seen that assumption fail!
I know of at least 1 gearbox application currently in series on a very well known car where they had to glue in a plastic 'press fit' bush after giving up trying to make it a tighter fit. Plastic is a great material until people start making assumptions on how to use it.

linearaudio · Post by **linearaudio** » Sat Sep 13, 2008 7:25 pm

know of at least 1 gearbox application currently in series on a very well known car where they had to glue in a plastic 'press fit' bush after giving up trying to make it a tighter fit.

Which is what Mr Ecosse was suggesting. Use Loctite 638 and your big problem will be if you don't get it in place quick enough! The idea of a bush which doesn't need reaming afterwards is very appealing! We use this principle re-bushing the rolls on cricket rollers- at 3" diameter it would be a bit of a bugger to ream, especially in line with the opposite end 4 feet away! ( I know this application doesn't heat cycle like a Moggy box, but Loctite is good over a fair heat range, and, as you are suggesting, the big boys of industry use it in similar situations).

Post by **les** » Wed Sep 17, 2008 9:56 pm

I thought I would update this thread as I have received a reply from where I bought these bushes. In fact I don't know how it happened so fast, but I sent the 2 faulty bushes back by 1st class post at 9.45am today and mid afternoon I had a phone call from the supplier who fully grasped the problem and was most apologetic remarking that he is going to return his stock and attempt to find another source, he had an original bush there and could see the difference, I was offered a cheque for both items or credit, this was esm, needless to say I was most impressed by this response .

Post by **rayofleamington** » Thu Sep 18, 2008 6:18 pm

Well done Les and ESM

Post by **bmcecosse** » Thu Sep 18, 2008 9:02 pm

Good business sense there at ESM ! Maybe they monitor this site - and can see trouble brewing. Either way - good sense for them to offer re-fund without any hassle.

Post by **les** » Wed Oct 01, 2008 10:29 pm

As an update for those interested, I have bought another tailshaft bush from a chap who advertises in the club mag, it fits and when reamed out still has a bearing surface left, success at last!