Vixen rear brake conversion

[alphaone]

Has anyone converted the rear brakes on a Vixen to discs? If so any tips please :-)

[tyracious]

For better rear brake performance:

One may wish to consider reducing the rear brake unsprung weight by fitting Datsun 240Z Aluminum drums or the Alfin style from Moss:
https://mossmotors.com/alfin-style-9-brake-drum-re...

And perhaps ditching the servo with an bolt-in install of dual master cylinders:
https://www.goodparts.com/product/dual-master-cyli...

This would allow correct balancing of the rear braking force.
It most likely would be advisable to have a setup where the rear brakes would never lock under any circumstances before the front.

For fast road the drums work fine if kept in good nick.

[Moto]

alphaone said:

Has anyone converted the rear brakes on a Vixen to discs? If so any tips please :-)

Do you have a braking issue you're trying to address ?

Moto

[alphaone]

Moto said:

Do you have a braking issue you're trying to address ?

Moto

The car was running 300bhp and the brakes was scary :-) When the rebuild is complete it will be running 400+ bhp so would like some additional braking. I started doing the brake lines last week when I thought it might be a good idea to change them over while the car is in bits

[GAjon]

We had the opportunity to track test the rear disc brake conversion on our M for the first time at Cadwell at the TVRCC track day.
Although we weren’t pushing that hard, because it was a first tack shakedown, we were very pleased with the brake performance.
We have a bias control in the cabin but we didn’t need to do any adjustments on the day.

We do have a brake specialist in the team now though.

[anonymous-user]

tyracious said:

For better rear brake performance:

One may wish to consider reducing the rear brake unsprung weight by fitting Datsun 240Z Aluminum drums or the Alfin style from Moss:
https://mossmotors.com/alfin-style-9-brake-drum-re...

And perhaps ditching the servo with an bolt-in install of dual master cylinders:
https://www.goodparts.com/product/dual-master-cyli...

This would allow correct balancing of the rear braking force.
It most likely would be advisable to have a setup where the rear brakes would never lock under any circumstances before the front.

For fast road the drums work fine if kept in good nick.

The Datsun Alfins are excellent and reduce the heat hugely, but being steel lined the weight saving isn’t much. We got two sets from the US and modded the edge to suit which is straightforward and at less than £120 all in a pair.

There is also an upgraded slave that can be fitted I had the ref but can’t find it. I think its off an Alpine or similar. Nothing about it on Triumph websites it was from a rebuild I read about and apparently it fits perfectly and gives 20+% more pressure.

[Moto]

alphaone said:

The car was running 300bhp and the brakes was scary :-) When the rebuild is complete it will be running 400+ bhp so would like some additional braking. I started doing the brake lines last week when I thought it might be a good idea to change them over while the car is in bits

That's serious power - I understand your thinking. I presume you're not running standard Vixen rear uprights with that power?

Likewise I'm in the process of rebuilding my braking system at the moment but with just 130 bhp I didn't have any need to upgrade, just needed everything to work as well as it could. So new steel drums wheel cylinders and shoes. Maybe I should have gone the Alfin route

Moto

Edited by Moto on Wednesday 26th January 20:38

Edited by Moto on Thursday 27th January 18:44

[StewB_v6]

I’ve got discs on the back of my Vixen S2 V8 & my 6200M Turbo. Both done differently due to hubs/uprights etc but all based around fairly readily available mass market hardware. Done in conjunction with front brakes (and suspension) too obviously.

Stew.

[anonymous-user]

StewB_v6 said:

I’ve got discs on the back of my Vixen S2 V8 & my 6200M Turbo. Both done differently due to hubs/uprights etc but all based around fairly readily available mass market hardware. Done in conjunction with front brakes (and suspension) too obviously.

Stew.

How did you do the vixen??

[StewB_v6]

Fabricated rear uprights with Nissan bearings/hubs & from memory Primera solid rear discs (they might have been some older style Honda Prelude discs - 4x114 PCD) & Golf 4 alloy hydra mech calipers.

Stew.

[StewB_v6]

Just checked my notes. I actually used Focus Mk1 rear discs & redrilled the PCD as I needed very shallow discs that were fairly thin to keep the unsprung weight sensible & the front to rear sizing balance sensible. I used the bigger Primera discs on the M with different Calipers.

Stew.

[anonymous-user]

This is the Morgan/Sunbeam Apline 0.875” slave, which gives significantly more shoe pressure than standard. They’re a straight fit. Girling part number 64670475

https://www.ebay.co.uk/itm/BMC-Wheel-Cylinder-Girl...

[anonymous-user]

V6 Pushfit said:

This is the Morgan/Sunbeam Apline 0.875” slave, which gives significantly more shoe pressure than standard. They’re a straight fit. Girling part number 64670475

https://www.ebay.co.uk/itm/BMC-Wheel-Cylinder-Girl...

Note 64670475 was fitted as Girling of equivalent to:
Series 1 & 11 Sunbeam Alpine
All Morgans: 1959-1988 (+4, 4/4, +8)

This would be a very worthwhile conversion!

[anonymous-user]

And the last if this trilogy:

https://www.ebay.co.uk/itm/PAIR-MORGAN-4-4-PLUS-4-...

—- a £23 brake upgrade -

[Moto]

V6 Pushfit said:

This is the Morgan/Sunbeam Apline 0.875” slave, which gives significantly more shoe pressure than standard. They’re a straight fit. Girling part number 64670475

https://www.ebay.co.uk/itm/BMC-Wheel-Cylinder-Girl...

Sounds interesting. However by increasing rear braking will this lock up rears under heavy braking and spin you around?

Moto

[anonymous-user]

Moto said:

Sounds interesting. However by increasing rear braking will this lock up rears under heavy braking and spin you around?

Moto

I believe not, according to a Marcos racer who gave me the info it balances well with better discs/pads up front. In Marcos circles it was an up-the-sleeve mod which clearly didn’t get to the TVR scene. I’ll certainly do it when I next do the rear brakes I think it’s a no brainier…

[GTRene]

V6 Pushfit said:

And the last if this trilogy:

https://www.ebay.co.uk/itm/PAIR-MORGAN-4-4-PLUS-4-...

—- a £23 brake upgrade -

thats cheap

[tyracious]

This sure looks like a tempting upgrade but I'll have to agree with Moto.
The last thing you want are the rear brakes locking up before the front.

These more capable slaves (reducing pedal pressure) may go well with the concept of chucking the booster and going with a balance-able dual master conversion from Goodparts. Theoretically it bolts right up in place of the booster.

Edited by tyracious on Friday 22 April 18:07

[anonymous-user]

The rears are way behind (literally) if grooved discs and green stuff pads are fitted, so these would even things up and would be probably nearer the feel of discs all round.
Morgans used the same Triumph front setup as the TVR so it’s proved to work. Don’t know about the Sunbeam.

[anonymous-user]

Dollyman1850 said:

It has all been done many many moons ago..

I am assuming with all this talk of bigger discs and calipers up front and bigger cylinders at the rear etc etc you are all confident of the size and capabilities of your std master cylinder and the amount of fluid it can move at the front and rear ports ??

I don’t know if bigger discs come into it, what I’m saying is it’s been a Marcos performance trick to change the rear slaves to make them more efficient and was also used on track/hillclimbs etc. it probably increases the efficiency to that of discs all round and let’s face it there are vixens with 4 pot callipers and suchlike and still running standard drum setups without balance problems.
Additional displacement is minimal so would have no practical effect on the displacement.