Winter project - T9 gearbox mods

[Sabbot]

One of my still to do winter projets is to try and work out a way of making the gearchange on the caterham less stiff across the gate. It is OK backwards and forwards (1th-2th and 3th-4th) but it spring that centralizes the change is overly strong when crossing up or down the gears 2nd to 3rd or 4th to 5th. I assume if I take the box out and take it appart I'll be able to modify the spring/s but wondered if anybody else in the forum has any bright ideas.

If I do end up taking the box out I might think about a set of different ratios (1st and 2nd are too far apart) so any advice on a good gear set to mate to a stock supersprint crossflow would be appreciated.

Thanks,

Stewart

[Sean]

Following are some gear sources, but all UK-based:

http://www.spcomponents.co.uk

http://www.bghgeartech.co.uk

http://www.quaife.co.uk

 

While you have the gearbox out, you may want to consider getting an O2 bung for a couple of bucks and welding it into the top as a filler, like this:

 

http://i321.photobucket.com/albums/nn384/BBL-Sean/7%20Build%20Issues/Gboxtop1.jpg

[bsimon]

Stewart,

 

I've not heard about altering the gate spring in a type nine, but FWIW, the gate spring is a torsional (close pin) type spring that centers the shift rod in the 3-4 gate between 1-2 and overdrive. I suppose it could be removed or weakened in some way. I'd be a bit wary in that you might end up stirring up the wrong cogs at times when engine RPM might not match road speed. The gate spring really makes it easy to feel which side of the gate you are in. I imagine it reduces a bit of shifter rattle as well.

 

I suppose one could do a bit of experimentation, but if it didn't work, it's an engine out exercise to restore it.

 

There is a "race" spring available for the forward/aft selector rod. It actually makes the selection a bit stiffer to keep the box from jumping out of gear during on/off power modulations. A particular problem with dog engagement 'boxes and syncro 'boxes with worn blockers or broken blocker springs.

 

There are a number of great replacement gear sets made for type 9 boxes if you wish to tinker. In the end, you'll probably have as much cash in the conversion as purchasing a reworked BGH type 9 from Caterham USA or other supplier.

 

Production gearboxes are designed with a one piece layshaft. You need to change the number of teeth on the layshaft gears to alter ratios. Most aftermarket gear sets are manufactured from scratch and are quite expensive as the gears are splined onto the layshaft. BGH actually slices and welds the Ford one piece layshaft to save costs. Rather clever actually.

[RossD]

Taylor Race Engineering is located in Texas and they deal with Type 9 gear boxes. I've never dealt with them but I've heard good things.

http://www.taylor-race.com/

 

(If you browse the parts section, look at the Quaife Sierra sections)

[11Budlite]

Stewart,

 

I'm not sure what could be causing your shifting issue but it might be worth removing the top cover/shift lever/reverse & interloc switches to make sure nothing is binding before you pull the engine/gearbox. A phone call or email to one of the experts mentioned above might be worth it as well.

 

I ended up upgrading my T9 with a BGH 2.8 sporting close gearkit several years back. The ratios are much more compatible with a light car like a Seven. If you've ever had one apart it's really not that difficult of a job. I do remember having to pick up a couple of different snap ring pliers that worked better than the ones I already had. There is some machining for clearance that has to be done, but I was able to accomplish that with a homemade tool and my drill press. It really came out well and has worked perfectly other than a slight oil leak from the input shaft seal that was fixed when I put in the proper double-lip seal.

 

Check out Cherik's website for an excellent write-up on his BGH upgrade: http://my.voyager.net/~quadrant19/Gearbox-upgrade.html

 

And here's a manual for the T9: http://www.biggles.net/download/Manual_Type9.pdf

 

I have also done business with Taylor and BAT and have been satisfied with both.

[Sabbot]

Thanks to everybody for their comments.

The link to the manual from Bruce was very useful and the links to the gearsets were food for thought. The weather in NJ is warming up so the chances of the box coming out are getting slim.

I'll probably end up living with the gearchange through the summer and keep an eye out for a merkur / sierra box to rebuild with a set of 5 decent ratios

Regards,

Stewart