Ribcase Gearbox Oil?

[jonclancy]

I'm using standard 20W/50 Halfords Classic in my box. It didn't really like a prolonged thrashing on our recent track day. Second became difficult to select.

What does everyone else use, please? Especially the fast-road/racers!

TIA

Jon

[Westfield 129]

Engine oil, but then your gearbox may be getting old, or your clutch is not disengaging well, and hanging up the 1-2 shift. I would check the clutch first.

40 or 50 weight should work fine. Or you can try Redline Shockproof Light.

[jonclancy]

Hi Jan,

The box was rebuilt only 1000 miles ago and is fine when cold.

I will try the clutch first - thanks for hte tip - If I bleed the fluid and be less lazy when shifting, that'll pinpoint if it's me or just the box baulking a bit when hot. I have an excuse - it was dark, chilly, and we had 100 miles still to run!

[Westfield 129]

Bleeding might help, or the slave/master cylinder may be at fault. Even though you don't show a leak, the pressure may be bypassing the seals, and this would cause the clutch not to completely disengage. If the clutch master cylinder was replaced, the clutch master rod may be fractionally too short. I had this problem during a replacement of the master cylinder in my own car. I fixed the problem by going back to the original rod from the old master cylinder.

Also, the graphite release bearing may be at fault, or the attachment of the slave to the clutch fork. However, I am still thinking hydraulics. Perhaps a replacement of the master cylinder, slave and the soft lines is in order.

The ribcase actually shifts quite well, especially when hot. This directs me to the clutch system as the culprit.

A little more information about the problem. Does it grind when shifting (we are not including 1st gear in this discussion), or just wont come out or go into gear?

If the problem is grinding, go to a higher weight oil. If it is just balky, stiff and hard to shift, it's the clutch.

[erictharg]

I run GL4 gear oil. 75/90 weight. Similar viscosity to 20-50 engine oil but designed for gearboxes so better additive pack for gearboxes. But the Midget gearbox is such a crude affair I'm not sure it makes much difference!

[jonclancy]

Thanks guys. I might try GL4 when I next pull the oil out (easy with my suction device).

I'm paying a visit to Canadian Tyre tomorow (first time in many, many years), so will look out for a Mityvac. They are affordabe on eBay, but probably cheaper in US/Canada.

I've currently developed a misfire (after a 2 hour run down to Dorset), so am investegating that at the moment. Lumenition and dizzy look OK, leads I have replaced, and will re-set the carbs up IAW the SU Manual when I next have some time off.

[Westfield 129]

I developed a miss. Cruinsing along at 4000 RPM, it just began to miss and run on 3 cylinders. 'Turned out to be a broken rocker. The adjuster just snapped off the scintered pressed metal standard rockers. Not unusual. I replaced the rockers with a set of Mini forged rockers when I got home. That worked fine until the top of #2 top ring land came off... I guess running between 4000 and 6000 RPM all the time took some life out of that old 1275.

If it is always running on 3 cylinders, pull the valve cover.

Having said that, most problems with SU carburetors start at the distributor. Pull the plugs and take a look.

There are a number of vacuum brake bleeder/fluid evacuators now. Many are made in Europe. Mityvac is not the only one. I use a Vacula, and the Motive Power pressure bleeder, which is very useful in one man bleeding of the brakes and clutch. The Motive Power bleeder is less than $50 US, and they ship to Europe. The standard "European" master cylinder cover works with the Girling type master cylinders, as well as all the standard Euro reservoirs. Also available through HRP World and other hard core race parts suppliers. The Motive Power bleeds all of the twin master cylnder car's brakes in less than 10 minutes. No pumping.

[jonclancy]

I was looking for a Mityvac while away on a trip, but Canadian Tire don't supply them. I'll try somewhere in SFO next week!!

So far I haven't pulled the plugs, but will do so, and will pop the rocker cover off for a look. BTW, does anyone else suffer from the oil filler cap being very close to the bonnet underside? I was thinking about changing the standard cover for an alloy one with a lower-profile filler cap.

I'll have a better idea over the weekend.

Also, if anyone is interested, I have found Mintex 1144 front pads at £31 from a local supplier. Part number MLB37M1144. Seems to be the same for Midgets as it is for later minis.

MLB37M1144 8.4” discs, late 1275 GT/1984 on callipers

Cheers

Jon

[sgrant]

Which cap are you using and which rocker cover are you using? Mine clears fine.

I think I remember Chris saying that he had clearance issues with his filler cap on him Mk1 XI and he had a new neck for the filler cap welded on lower down the cover, on the side.

stephen

[jonclancy]

Hi Stephen,

It's the standard Midget "filter" cap and rocker cover.

Some images are here:

http://s94.photobucket.com/albums/l96/j ... %20Engine/

Jan,

I popped the rocker cover off and it all looks very nice under there. Plugs are all rich and the threads look a little wet.

I have made my own cut-down jet spanner, so will get the book out and try to ball-park it over the weekend sometime.

Because of the inaccesibility of the timing marks, the timing was set on the Dyno to give best HP. There was a lot of pinking so the mixture was adjusted.

Anyone use a normal timing light? Seems to be a challenge to see the marks unless the car is on a ramp! How did they do it when the engine was installed in the Midget?