350i S2 Princess 4 pot conversion

[Jack Valiant]

Guys I know this has been done somewhere before but thought it might be useful for people going down this upgrade.

After a bit of thought and the timely availability of some calipers (thanks Andy!) I decided to tackle this worthwhile upgrade from the traditional 2 pot Granada vented disc system to the Princess 4 pot calipers keeping the Granada vented discs

So this was the the fitted system:




Fitting the new Princess calipers is well documented elsewhere however I went for some stainless hoses and a 'T' piece attached to the caliper flexible hose mount (thanks again Andy) and the lock tabs for the mounting bolts. Pictures tell a thousand words so here goes:







Bleeding the system is a little tricky but after 4 cycles normal service was resumed. Notice the "green hue" on discs from the fitted Green Stuff pads! So in terms of comparison of the two systems...

Feel on the pedal is a little firmer, braking performance, well early days as they will need a few miles on the pads but early signs are an improvement. Is it worth doing ... I think it is one of those upgrades that is worth doing. I will comment again when I have a 100 or so miles on them

Cheers

Chris

[johntom]

Hi
i've recently got some 4 pot princess calipers and the rebuild seals etc ready for some winter tinkering.
Could you confirm the width of the spacers between the calipers and what is the part number for the green stuff pads?
Also which holes do the braided lines feed into, my calipers have got the copper link pipe fitted, not sure if i need to convert to the 't piece' set up?

[Brap_Brap]

I wonder if my spare pair of Aluminium RX-7 calipers will fit a wedge?
The rim bolt hole patter is the same.
The rotor is about as thick.
Rotor diameter looks to be the same.

I should try this. Less unsprung weight... and I can testify to their stopping power,
it puts a wedge to shame with 500lbs more to stop.

[Jack Valiant]

Well just say that I have put 50 miles on the pads everything has settled down well. So my comments on the conversion over the standard granny setup would be:

• Brake feel is firmer
• Brake performance is better I would say by 25% once the green stuff pads have some heat in them.

Worth doing? - Yes

Chris

[dixiebabes]

johntom said:

Also which holes do the braided lines feed into, my calipers have got the copper link pipe fitted, not sure if i need to convert to the 't piece' set up?

I'm about to start this upgrade and I'm going for the copper link pipe as thats what the rally lads recommend. I have been told I will need longer bolts for the calipers and locking tabs to keep them on place, is there anything else I'm gunna need before I start pulling it to pieces?


Dix.

[Jack Valiant]

If you have the standard set up as i did with the Granny calipers then I did not need longer bolts. Likewise the locking tabs on the bolt plate if in good order can be re-used. I looked at the cross over pipe option but as the Princess had dual circuit I decided to use stainless pipes and a good quality 'T' piece. Personal taste I guess. Be prepared to spend some time and patience on the system bleeding mine took 4 cycles to get all the air out I did the rears as well so did a complete fluid change at the same time. Good luck!

Chris

[mrzigazaga]

johntom said:

Could you confirm the width of the spacers between the calipers?

I have 10mm spacer's in mine which i believe you need with the vented disc's...Not sure about the pads as i have the princess pads..Ziga

[johntom]

Hi
Were the braided hoses specific or did you have them made up?
Also do you have a picture showing which holes the hoses feed?
Thanks

[dixiebabes]

Jack Valiant said:

If you have the standard set up as i did with the Granny calipers then I did not need longer bolts. Likewise the locking tabs on the bolt plate if in good order can be re-used. I looked at the cross over pipe option but as the Princess had dual circuit I decided to use stainless pipes and a good quality 'T' piece. Personal taste I guess. Be prepared to spend some time and patience on the system bleeding mine took 4 cycles to get all the air out I did the rears as well so did a complete fluid change at the same time. Good luck!

Chris

Hi Chris thanks for that mine is a 1983 series 1 and currently has
Solid discs and I believe grandad pads and calipers. I thinks the locking tabs are in good nick, so all I need to do hopefully is link the caliper with hard pipe and Bobs me uncle. Oh Aye and bleed it. By the way did the backing plate foul on the caliper and need trimming or did they go straight on?


Dix

[mrzigazaga]

Hi Dix..If you need vented discs then the brembo ones fit that i posted up previously, You will need a 10mm spacer and possibly longer split pins though...Cheers...ziga

[dixiebabes]

mrzigazaga said:

Hi Dix..If you need vented discs then the brembo ones fit that i posted up previously, You will need a 10mm spacer and possibly longer split pins though...Cheers...ziga

Cheers Marcos gas wedge has loaned me a pair he bought very cheaply to try and see if they fit, it will have to wait till I have sorned the car though.

Dix

[GV]

If you are running with Granada vented discs - these have a 24mm width. 10mm spacers with princess 4 pots are not wide enough. I had 15mm spacers made up for the calipers Jack V now has on his car.

[Jack Valiant]

Hi Andy when I did a quick check I thought they were 10 mm spacers so thks for the correction. Anyone doing this upgrade will need the extra long split pins and correct size anti sqeal clips

Chris

Edited by Jack Valiant on Wednesday 12th September 18:25

[dixiebabes]

Ill check when I get home but must have the 15mm spacers already on as I have had everything together on the bench and it all fitted pistons fully depressed. So I'm hoping its ok.

Dix