Clutch release arm

[DavidL]

An update on this thread. I've not yet found the source of my issue, which is the transmission grinds when shifting into reverse, but only when the car is warmed up. I've replaced the hydraulic clutch hose (a bit of a saga, the one from Caterham is too short, so I had one made), and with the linkage tight, I've been moving the slave forward by adding washers between it and the bellhousing. That will pull the clutch lever further at full travel. However, it has not helped. Josh Robbins at CAterham USA suggested I inspect the plastic "saddle" at the bottom of the shift lever.

 

Any advice on whether it's possible to get to it without removing the gearbox? As best I can figure, I'll need to remove the seats and then remove the carpting and the attached shift boot. Does anyone know if I'll be able to get into th shift lever asembly throught he tunnel?

 

Thanks, -David (1990 1700 SuperSprint Xflow Caterham, Ford T9, DeDion)

[panamericano]

Maybe silly question. Are you putting it in first or second before trying to go to reverse? It's helpful on a lot of transmissions.

[DavidL]

typically I go from neutral to reverse, but I have tried the trick of going into 4th and then quickly over to reverse (to stall the layshaft if the clutch is dragging a bit)... it doesn't help.

[Anker]

Often the problem isn't the gear box, but the clutch dragging. Try pumping the clutch pedal and see if it makes a difference.

[Dave W]

You could try adjusting the push rod at the master cylinder. That might give you enough extra stroke to reduce the clutch drag. As long as you have 1mm of free travel before the push rod contacts the piston you should be OK. Dave W

[Anker]

Sometimes the push rod cannot be adjusted enough. That was the case with my 7 that has a hydraulic clutch. Instead of a proper lock nut it had a regular, thicker nut. The 1-2 mm extra that I got when I replaced the nut was enough to fix the problem, at least for a while, until I realized that the main problem was a worn-out master cylinder. :-)

[DavidL]

Thanks everyone for the thoughts.

Re the M/C: I have replaced the seals, and I think adjusted it's pushrod with just a bit of freeplay, but worth rechecking. Thanks for the pump-the-pedal suggestion, tht would point to a bad M/C. If do know that if I hold the pedal in, the slave moves and then holds. I think I bought the M/C from Chris T. at Sevens and Elans a decade ago, who told me he preferred to replace rather than rebuiild them. Perhaps I should have just done that.

 

At the slave, the rod still has about a 1/2" of threads visible, so a thinner lock-nut won't help, if I understand the argument.

 

I'll report back when I've got more data!

Edited February 3, 2021 by DavidL

[Anker]

Replacement masters are very inexpensive. Apparently they are used a lot on race cars and get replaced annually.

 

Make sure you test the play in the slave correctly. Have someone step on the pedal while you look at the clutch mechanism.

[DavidL]

Well, it's two years later, but I fixed my clutch problem.  This Fall I pulled the engine and gearbox and replaced the clutch with parts from RedLine Components in the UK.  

I replaced the clutch plate, clutch cover assembly, throw-out bearing, pilot-bearing, and the clutch arm pivot pin, and also had the flywheel refaced.  None of the old parts were obviously broken or worn out, but after reassembly (and repalcing a bunch of other items while it was all out), the clutch is fixed, it no longer drags when warm!  That was a big relief.  As mentioned earlier in the thread, all the hydraulics were replaced first, but that didn't help.