Technical Article - Manual Gearbox Expose

404 and 504

The BA7 gearbox was fitted to 404s from 1968 and 504s throughout their production. These gearboxes can be expected to work for well over 300,000 kilometres. At this distance you can still expect the gearbox to work well; but there may be some whining noises while using first, second, third and reverse and noise from the bearing between the input and main shafts - this noise can be heard by engaging (noise present) and disengaging (noise absent) the clutch in neutral.

There are two problems which will shorten the life of a BA7:

1. It is common for the gear linkages going into the extension housing to leak oil. It is essential to check the gearbox oil level during regular servicing because running out of oil will considerably shorten the life of a gearbox.
2. There are semi-circular spring steel clips in the synchromesh cone assemblies which can break in two. Usually the fragments fall harmlessly into the bottom of the gearbox and emerge at the next oil change, attached to the magnetic drain plug. Occasionally, the fragments will fall into a cog and this causes a catastrophic failure. It is rare for the synchromesh clips to fail and I am not sure why it will happen to some gearboxes and not others. If the synchromesh clip is missing then you will find that the synchromesh will be weak on two gears, either first and second or third and fourth.

505s

The five speed gearboxes fitted to 505s have never come up to the expectations of durability and smooth operation built up by the BA7 gearbox.

Early 2 litre 505s were fitted with the BA10/5 gearbox, which was originally developed for the 604. When this gearbox gets a little old it is common for the synchromesh to be weak and for there to be stiffness when shifting into gear, especially when cold. In common with the BA7 they are subject to oil leaks and synchromesh clip failure.

Later 505GRs and all 505 SRs, STis and GTis use the BA7/5 gearbox. This gearbox seems to overcome the weak synchromesh and stiff shifting problems of the BA10/5 but have introduced a new and terrifying problem; somewhere in between 200,000 and 300,000 kilometres it is common for the fifth/reverse sub-shaft bearing to fail. This shows itself by a noticeable increase in noise while using fifth gear.

The fifth/reverse sub-shaft is driven by a splined extension of the intermediate shaft (also known as the cluster gear or lay shaft). If this noise is ignored then the splined extension will break off - thus destroying the intermediate shaft. A supplier in Sydney who specialises in scavenging parts out of failed gearboxes said this is the most common failure in BA7/5s. He quoted $900 for a new intermediate shaft and $300 for a good used one, if one could be found.

If you detect an increase in the noise from fifth gear then immediately desist from using fifth. If the gearbox is in otherwise good order then I recommend simply replacing the failed bearing. This can be accomplished with the gearbox in the car and can be done for less than $300. This is more palatable than spending $1,500 replacing all bearings in the gearbox, whether they need it or not.

The information presented here is based on my experience and conversations with repairers and parts suppliers interstate. I spoke with one local Peugeot repairer on a number occasions and, surprisingly, he was not able to contribute any knowledge on common problems and solutions. In this context, I recommend that you get a lot of advice before being tempted to pay for any major gearbox work.

Bill McNamee