4722 replies to this topic

[TFD]

+1. 

 

Not saying you dont, but please check things before going big with rear brakes. Had the experience some years ago with a Nissan 100NX locking the back end.... tell you... not funny.

On the other hand, I like this idea. Was talking to Smiley the other day about Brembo's (or porche for that matter) on the front.

 

Good luck.

[CocoPops]

Ask SteveA about locking rears...

[mbes2]

Great to see Nipper is still getting the mod treatment ! 

 

Keep up the fantastic work Nev

[Nev]

 

Ehhh, It's not always an improvement when you can lock up rears so easily and slam rearwards in a hedge, so clearly that is not a properly matched combo...

 

But to the OEM upgrade; 40mm pistons instead of the 36mm standard size will give you 23% more clamping force at the rear, which maybe is enough for most here...

 

 

I didn't say it was my intention to lock the rears up first. The intention is to shrink the difference (which is too much on my car) between the fronts locking and the rears locking. Remember locking out front wheels way before the rears mean unnecessary loss of steering by not maximising all 4 contact points with the tarmac.

 

Edited by Nev, 04 February 2015 - 05:32 PM.

[Nev]

What is the weight difference Nev between a set of 350mm discs and Porsche breaks vs the standard VX setup?

 

I don't know yet, as we haven't started the project, though those calipers were a little larger and heavier than I expected. The battery on my electronic scales is dead too, so couldn't weight them.

 

Josh says his slightly smaller calipers, with 298mm x 22mm rotors was considerably lighter than the OEM setup, particularily at the rears.

 

In my case if the setup stays approximately the same weight as OEM I will be happy. The larger diameter rotational mass of the rotor will give more gyroscopic effect too.

 

At the end of the day I would prefer being able to really kill speed properly fast whilst possibly losing a little bit of nimbleness and rebound time of the floating assembly (if it gets a smidge heavier). Remember, the primary mechanical thing that will alleviate a front end impact is effective brakes, so this is why the project is important.

Edited by Nev, 04 February 2015 - 05:49 PM.

[Nev]

Was talking to Smiley the other day about Brembo's (or porche for that matter) on the front.

 

 

Porsche calipers are Brembo calipers.

 

They are well made things from my brief inspection, beefy and lots of material in the body to stop twisting, also the M12 mounting bolts indicate a more serious application than the slightly weedy looking M10 bolts that the AP units use. When we make the bracketry/spacers, I am hoping to use all 4 mounting holes into the Elise Parts hub carrier, thereby making the whole assembly more rigid/robust than the OEM setup.

 

If the Brembos can stop a 1300Kg Porsche GT2 doing 200 MPH then they should have an easier job on 940 Kg of Nipper, so long as we fettle it all correctly.  

Edited by Nev, 04 February 2015 - 05:42 PM.

[Exmantaa]

 

 

Ehhh, It's not always an improvement when you can lock up rears so easily and slam rearwards in a hedge, so clearly that is not a properly matched combo...

 

But to the OEM upgrade; 40mm pistons instead of the 36mm standard size will give you 23% more clamping force at the rear, which maybe is enough for most here...

 

 

I didn't say it was my intention to lock the rears up first. The intention is to shrink the difference (which is too much on my car) between the fronts locking and the rears locking. Remember locking out front wheels way before the rears mean unnecessary loss of steering by not maximising all 4 contact points with the tarmac.

 

 

 

I know you're not an idiot...

 

Have my own braking problems with the track sled, as my braking is much worse than exatly similar set-ups on track and I can easily lock's up the fronts... Rear pads(CL5+ around) seem not to wear much, so need to sort that out soon,  

[Nev]

I made up a trial 350mm x 24mm disc out of wood to dummy the parts up.

This morning's first trial has worried me a bit, all the parts look overkill in size, though looking by eye they will approximately fit.

The problem I face is that the Elise Parts hub carriers have 6mm more diameter (in the vertical plane) than the OEM hub carriers. This means that in order to make a spacer/bracket that has enough depth to safely put bolts into, the caliper has to be pushed outwards, which in turn means larger diameter rotors. The question is by how much. Maybe we could get away with just 330mm rotors and then mount the smaller boxter calipers.

Also, the Porsche pads are 60mm width (instead of 50mm width), which means a slightly wider rotor. I will have to ring round to see if anyone can offer 350mm x 28m with 60mm swept pad surface rotors.

Edited by Nev, 07 February 2015 - 09:35 AM.

[TFD]

Stuff looks like you're able to get your back all the way up when hitting the brakes. Reversed wheelie action lol.

[CocoPops]

How does wood compare to iron or ceramic discs?

[MAXR]

How does wood compare to iron or ceramic discs?

 

It depends on the wood, surely?

[hairy]

How does wood compare to iron or ceramic discs?

 

Apparently used on the Montreal metro https://www.youtube....h?v=MdvQLYC5hGc

[Nev]

How does wood compare to iron or ceramic discs?

  Apparently used on the Montreal metro https://www.youtube....h?v=MdvQLYC5hGc

Incredible, who would have thought of that !

[smiley]

Can you take a pixie of a pad for the porsche caliper, versus oem size Nev?

[Nev]

Can you take a pixie of a pad for the porsche caliper, versus oem size Nev?

Ok, will take some when I actually start the project and take it all apart. Am off skiing this weekend, so there won't be any progress for a couple of weeks.

[Nev]

It was actually sunny today so I went for a 160 mile trip round the Welsh hills (with the top off and my hot air blaster full on so it was roasting in the cabin).

Road conditions were very variable, what with salt, mud, damp patches, gritters spraying. Still great scenery though, I pitty you poor souls living in the crowded cities and SE.

Bearing in mind I washed Nipper last weekend, I think there may still be a bit of salt on the roads...

Edited by Nev, 08 February 2015 - 05:33 PM.

[Tonie Pettersson]

Fantastic car, what a project!

[Nev]

Fantastic car, what a project!

Thank you Tonie, nice of you to say so.

[joshua]

Hi - a little info on this set up which I've had running very successfully for a couple of years.

 

Brembo calipers front and rear as found on Boxster and various later 911s. Small independent handbrake calipers.

Rotors installed 330 x 22mm with built in option to use fatter discs but seems not required after 20k hard miles with little wear and no warpage. Alloy bells. Pads Mintex 1144.

Weight loss per corner around 1.5 kg front 2.5 kg rear.

Oem master cylinder replaced with Subaru item but using oem VX servo. 

ABS has in car switchable hydraulic bypass, still fully functional if required.

Wheels 16"front 17"rear.

 

Total cost just short of £1600.

 

When system first installed car had by far too much front bias. I rectified this at first with different compound pads. Now there is an in car adjustable bias valve limiting front brake circuit to give any desired front <-> rear balance from locking fronts to locking rears.

[fezzasus]

That's the colour a car should look! Glad you're making use of it, the trouble with tinkering is it can become all encompassing and stop you from actually using it.