TR6 with TR6 pedal box and MC in TR4?

[Alan_Myers]

Hi all,

I'm considering a modification to my TR4 and need to ask a few questions.

I have an old spare TR6 pedal box assembly and thought this might be a good way to install a dual circuit brake system, something I've planned to do to improve on the single circuit in the TR4. It's non-original, I know, but the car is pretty far from originality, anyway.

Unfortunately, I don't have a TR6 handy to look at and compare. I want to think this through pretty thoroughy before doing any modifications to the car or the pedal box. So, I gotta ask some possibly dumb questions.

First of all, were all TR6 fitted with a brake servo? I see that the mounting for the brake MC on the TR6 pedal box has a large hole with four bolt holes around it. Those obviously won't match up with the two mounting ears and bolt holes on the brake MC (don't have one of those yet, either). If some TR6 were not fitted with a brake servo, is there in adapter or bracket of some sort that the MC mounts to, then to the pedal box, or is there a second type of pedal box used to allow for direct mounting of the MC, or a different type of MC? I hadn't planned to install a brake servo.

Another thing, has anyone ever fitted qrease zerks to make it easy to lube the pedal shaft? Seems to me it would be relatively easy to drill and tap the tubular portion of the pedals themselves, postiioning a couple grease fittings to allow a little to be squirted in there every so often. I can't think of any downside... except I'd have to be careful not to overgrease it, to keep from having globs drop onto the driver's floor area.

Also, the pedal box and the pedal arms themselves are pretty heavy (about the same as TR4, though). Has anyone ever done some lightening to these parts? I'd think it could be improved quite a bit... carefully of course.

Finally, I see how the brake pedal return spring doesn't line up very well, looks like it will foul with the brake light switch. I think there was a recent post here on BCF about this, but wanted to be sure I understood it correctly. I'm thinking about welding on a short, secondary arm just for the return spring, to better line it up with the other anchor point and avoid the brake switch and it's bracket. Any alternative suggestions?

Any insights would be very much appreciated! TIA!

p.s. This assembly needs some other restoration work, too: new bushings, return springs, clevis pins and circlips are the obvious things. Thankfully, I've got all the major (NLA) parts in good, usable condition.

Cheers!

 

[PeterK]

Hi Alan,

For my 4A, I purchased the front bulkhead repair panel from TRF that already has the holes for the servo and pedal mounting. If you want I will trace the holes for you as a template.

There is an aluminum spacer between the servo and the TR250/6 m/c. The spacer is tapered top to bottom so the m/c will sit level in the car. The spacer bolts through the bulkhead and the m/c bolts directly to the servo.

I am not aware of any 250 or 6 that did not have the servo fitted.

It is an easy retrofit for the 4A to give a dual circuit. I think the 4 shares the same bulkhead as the 4A.

 

[Alan_Myers]

For my 4A, I purchased the front bulkhead repair panel from TRF that already has the holes for the servo and pedal mounting.

That's a quick easy solution! I was just planning to hold the pedal box up in place and scribe marks for the various holes, then cut/drill them out. I think I'll check out the repair panels from TRF, too. Thanks for the offer to trace them, though.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]
There is an aluminum spacer between the servo and the TR250/6 m/c. The spacer is tapered top to bottom so the m/c will sit level in the car. The spacer bolts through the bulkhead and the m/c bolts directly to the servo.

I am not aware of any 250 or 6 that did not have the servo fitted.

It is an easy retrofit for the 4A to give a dual circuit. I think the 4 shares the same bulkhead as the 4A.
[/QUOTE]

Aha! The spacer explains it all. That's what I'm missing. I wonder if it could be used directly, to mount the MC right to the bulkhead without the servo? I really have no place on the car to pick up vacuum to operate a servo anyway (and with the cam that's going in it, there it would probably need to be boosted with an elect vac pump anyway).

Cheers!

 

[PeterK]

You just need to drill and tap one of the intake manifolds from your webers to provide a vacuum pickup for the servo and run a 3/8" vacuum hose to a non-return (one-way) valve to the servo. Not sure if you can get enough pedal pressure from the m/c without the servo. I have seen several race cars with this setup including the servo and vacuum tap.

 

[DNK]

Alan- The spring tab for the brake is not used on US cars.Just on the clutch.

 

[Down Under Bill]

That's a quick easy solution! I was just planning to hold the pedal box up in place and scribe marks for the various holes, then cut/drill them out. I think I'll check out the repair panels from TRF, too. Thanks for the offer to trace them, though.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]
There is an aluminum spacer between the servo and the TR250/6 m/c. The spacer is tapered top to bottom so the m/c will sit level in the car. The spacer bolts through the bulkhead and the m/c bolts directly to the servo.

I am not aware of any 250 or 6 that did not have the servo fitted.

It is an easy retrofit for the 4A to give a dual circuit. I think the 4 shares the same bulkhead as the 4A.

Aha! The spacer explains it all. That's what I'm missing. I wonder if it could be used directly, to mount the MC right to the bulkhead without the servo? I really have no place on the car to pick up vacuum to operate a servo anyway (and with the cam that's going in it, there it would probably need to be boosted with an elect vac pump anyway).

Cheers!
[/QUOTE]
I Have converted LHD US model to steer from the right side. (Pun intended) Had all the various bolts bored through the and then put the P/Box in place inserted screws bolts and ran a 1/8 drill through the bulkhead then enlarged. All holes in exactly the exact place. Same with Master Cylinder brake booster location. Pedal Boxes from what I saw are ambidextrous. Down Under Bill

 

[malbaby]

Assuming your car is RHD...
The only downside with the TR6 system is that the clutch master cylinder is very close to the rear carb, which greatly limits your choice of air cleaner.
Remedies...soft small air cleaners....remote reservoir for the clutch [preferred option]...or fit the TR4 clutch M/C in it's original position with a custom made clutch pedal.