Sierra type 9/N gearbox synchros and blocker bars

[cmsapms]

Gearchanges, especially 1st and 2nd, were becoming more and more obstructive/noisy. Trying to select 1st with the vehicle moving was all but impossible, and changing into second particularly from 3rd caused a graunch.

Having removed/stripped the 'box (Ford type 9 5 speed attached to a Vauxhall XE engine), I've found the following:



As you can see, all the blocker bars have a chunk taken out of them (red circles) and the resulting sharp edges have eaten into the 1st gear synchro ring (green circle). I guess this is causing what might be termed over-indexing of the synchroniser sleeve which is preventing the sleeve sliding fully home. I also think the blocker bars are hanging up in the groove they've formed preventing the 2nd gear synchro rings working properly.

When I first installed the 'box in the car (Westfield) back in 1997 it was an unknown quantity, from a scrapped Sierra, so it's lasted pretty well - many track days and road miles - so I can't complain about longevity.

Anyway, time for a rebuild. I've bought all the necessary bits and looking at the new blocker bars, I notice that they are made of pressed steel. It's basically a bit of flat steel folded to make a shallow box shape, but the corners are just left butting up to each other. It's obvious that the folded end gives no support to the sides. It seems to me that a bit of silver solder in each corner would give a lot of additional strength.

So, the question to PH's gearbox gurus is: what might the downsides be to this idea? Are these items likely to be heat treated and, if they are, would the heat of silver soldering affect this? I ruled out welding and brazing due to heat and lack of capillary action for the relatively fine gap between the two folded edges.

Grateful for any suggestions (including leave well alone!). Perhaps I should just accept that an unknown mileage in a repmobile followed by nearly 20 years of enthusiastic driving is the limit for these items?

Paul

[Mignon]

It may be that a little flexibility in the bars is a good thing to prevent them being too abrupt in engaging with the cut outs. If you got 20 years out of the original ones then worry about it in another 20 years.

[stevieturbo]

For other boxes, some places off billet pieces....

but as Mignon says. The current ones have worked for decades, there's little reason new ones wont do the same.

But I doubt you'd do any harm soldering them up ?

[cmsapms]

There is a company advertising billet blocker bars for this application, but they've been out of stock for a while. I think I'll do a quick experiment on one of the broken items and see how successful it is and then decide whether a 20+ year service life is acceptable

[PaulKemp]

BGH Geartech are a long standing builder of Type 9's and there is a lot of advice on their website
They are also open to giving advice

I noted a magazine piece some years back where modifications to the gearbox case improved oil feed as well as different materials for components such as blockers and baulk rings.
I suppose it all depends on the torque your putting through the box and the type of driving you'll do