AP master cylinder pushrod thread size

7 posts / 0 new
Last post
Nigel B
Nigel B's picture
Offline
Last seen: 27 min 26 sec ago
Joined: 17/04/2014
AP master cylinder pushrod thread size

I've spent a rather chilly afternoon in the garage, attempting to optimise my pedal positions for heel and toe. 

It's been a rather frustrating process & I can't seem to get the brake pedal quite where I want it in relation to the throttle. I'm ALMOST there, but not quite!

On the forward-most pedal mounting position, the pedals need to be adjusted up towards the driver & I run out of thread at the end of the master cylinder pushrod. If I try the rear-most mounting position, I run out of adjustment in the opposite direction. Whilst adjusting the pedals down & away from the driver, the end of the pushrod makes contact with the top of the pedal, before the pedal has reached the required position. 

It seems to me I have two options. I could extend the pushrod on the foreword mounting position, with an extension piece or a longer clevis, or I could use the rear mounting position & chop a bit off the pushrod. I feel inclined to take the first approach, as it's more easily reversible if I have second thoughts & I'd rather have the pedals & seat further towards the front of the car, to give me a bit more luggage space & leg room if friends with longer legs than I have want to drive the car. 
 

A lot of the clevis devices & extension bars are threaded, but after much Googling, I haven't managed to determine the thread size on the master cylinder pushrod. 
 

Any advice would be much appreciated!

Cheers, 

Nigel.

Tazio
Tazio's picture
Offline
Last seen: 2 hours 31 min ago
Joined: 17/04/2014

Not the answer you are hoping for, but at McMillan Motorsport, I've watched them use strong arm tactics on the pedals to get them in the optimum position for heel and toeing...

Nigel B
Nigel B's picture
Offline
Last seen: 27 min 26 sec ago
Joined: 17/04/2014

It's very frustrating! I can't recall having problems with my first 7, that was perfect for heel & toe from the off. 
 

I did have to bend the throttle pedal slightly on that one, but that was because I wasn't getting full throttle (& the throttle stop was the bulkhead in those days!). 
 

Perhaps I'll have to resort to strong arm tactics again?! Grumpy

7 wonders of th...
Online
Last seen: 2 min 32 sec ago
Joined: 17/04/2014

My AP is M8, whereas the Girling clutch cylinder is 5/16", you can get new pushrods with either thread and in various lengths though too.

Nigel B
Nigel B's picture
Offline
Last seen: 27 min 26 sec ago
Joined: 17/04/2014

Thanks for the info, that's great! I didn't realise you could simply swap the pushrods over. Do Caterham supply them? A slightly longer pushrod on the brake master would be all that's required, it just needs a tiny bit more adjustment.

7 wonders of th...
Online
Last seen: 2 min 32 sec ago
Joined: 17/04/2014

there are some on ebay though you could speak to AP too, very helpfull people

Nigel B
Nigel B's picture
Offline
Last seen: 27 min 26 sec ago
Joined: 17/04/2014

Thanks for everyone's comments. 

I had quite a long chat with Alan at AP this afternoon & although they do supply push rods of varying lengths for some of their master cylinders, they only have the standard sized pushrod for the Caterham one.

On the subject of pushrod thread sizes, apparently the Caterham CP4627 uprated master cylinder can be supplied with either M8 or 5/16 UNF pushrods & the serial number etched onto the underside ends in either PRM for the metric or PRT for the imperial version. My master cylinder didn't appear to have either code as part of the serial number, but after examining the thread closely, I'm pretty sure it's the M8 version. 

After much Googling, I've ordered an M8 threaded clevis from Motorsport Tools. They do them in two lengths & I've ordered the longer version, which should provide me with sufficient adjustment, fingers crossed!

So cheers again!

Nigel.