Technical Rear disc conversion

[Smiler121]

Strikes me that the drums look far deeper than 10.25mm & therefore require a decent depth spacer unless I'm missing something?

Anyone have a convenient way of measuring one - say a set lying around in the garage?

 

[GoBe]

That measurement is taken at clearance hole for the wheel bolts on a maxtorQ disc and a drum off my Cinq sporting. So to return the offset to the standard you need to add a 4mm spacer. If you think that's wrong why don't you remove the drum and measure, I know that some aftermarket drums aren't to fiat specs.

 

[randomizered]

I also have a set of drums and discs in the garage. I'll check later to confirm, but 4mm does seem just right

 

[MRodz]

OK, we've recently been having a little discussion about rear discs on a polish forum. One guy that had them claims that they're just too strong for such a little car and it becomes very unstable when stopping from higher speeds (from over 100km/h). Anyone had this problem? TBH I've never heard of this before...

 

[arc]

no, nothing like that in my car - and i've done high speed brake testing. I have 257mm front discs, and 240mm rear discs.

 

[randomizered]

no, nothing like that in my car - and i've done high speed brake testing. I have 257mm front discs, and 240mm rear discs.

:yeahthat:

Same setup and no issues here.

 

[J333EVO]

Can't say we have had any issues either, same set up again 257mm front, 240mm rear, and it has been icy recently and I think that any over braking at rear would have been exposed.

There were some thoughts on this before (m)any of us on here had done the rear conversion with tails of woo, and that it would be dangerous, but never encountered them.

 

[fingers99]

I'd imagine that if you did the rear disks and left the fronts as is, it might get interesting. As is, perhaps the most remarkable thing is how similar it feels to one with big brakes up front and disks at the back.

 

[cc1]

The rear brakes for a Cinq 700cc are the same as all other models and run 145/70/13 tyres and works ok unless you try bursting the brake seals.
Most poeple with rear disc conversions will, I presume, have 175, 185 etc tyres and sport suspension which cuts down on dive and weight shift.

 

[randomizered]

Battery's flat in digital caliper, but it has a nice scale as well, so i could get a decent accuracy.

Brembo disc thickness - 6mm

OE hub thickness - 10mm

So I can also confirm 4mm spacers are required, and anyone who doesn't fit them has effectivly reduced their rear track by 8mm overall. Not a massive problem for 5.5" stock wheels with regards to fitting, but on mine, it was simply too much of an offset change and they wouldn't go on!

They DO NOT have to be hubcentric, as you will still have the same amount of centering ring as with the stock drums.

Kristian

 

[balidey]

I don't think its as easy as that. The caliper needs to be centralised over the disc, the caliper mounts on the outside face of the adaptor plate. If the adaptor plate is thicker, the caliper moves out, if its thinner, it moves in. I think it depends on the thickness of plates too. I'm not saying the disc and drum thicknesses aren't important, but its not the entire story.

 

[randomizered]

Your right, if you have a thick adapter plate, then you need even larger spacers...but.....to retain the original factory offset on the wheels, you need 4mm spacers.

The adapters Jordan sold are thin enough that i needed to install spacers between the adapter adn the caliper mounting arm, to move it further outward. You'd have to go about 1-2mm thicker than his adapter to run into those issues.

Kristian

 

[balidey]

Ah, Ok. Thanks. Makes sense.

 

[GoBe]

I've been designing some brake mounts recently & the recommendation I keep getting from people is to design them so that you shim the calliper/mount to centralise the disc, that way you can easily take out any skew problems without the need to shim the disc.

 

[randomizered]

Which is exactly what I had to do.

One benefit over the mounts in the group buy, could be to have the centre hole milled out to 58.1mm, so its a tight fit over the centering hub. THat way the 4 bolts will be under less load. Not a biggie though i guess, sure they aren't under that big a force.

Kristian

 

[soozukisteve]

I have just Fitted Bravo 1.8 16v front discs/calipers and greenstuff pads to my seic and it has made such a huge improvement i have decided to go for the backs aswell(mostly for reliability and cosmetic reasons)
I have sourced some Tempra (1994/1.9l)complete rear arms and having followed the thread for a while,was wanting to ask a few questions.
Please forgive me if i have overlooked any info already mentioned!!
The Tempra discs are 40mm in total width and i have kept the tempra caliper mounting brackets which are approx(havent cleaned all the crap off them yet) 6.5mm thick.They will need to be machined to fit properly anyway,but was wondering before i start,if i will have any spacing issues as i intend to use the original seic hubs.I have read a few posts with approx measurements but could do with a definative answer if pos....
The seic is my only mode of transport at the mo so i cant have it stripped down for a trial run!

 

[balidey]

I too am using tempra bits, but you will not be able to 'machine the tempra plate' as the mounting hole positions are different and the centre hole is way too small. I think by the time you have machined it you will not be left with much metal.

 

[soozukisteve]

I too am using tempra bits, but you will not be able to 'machine the tempra plate' as the mounting hole positions are different and the centre hole is way too small. I think by the time you have machined it you will not be left with much metal.

Did consider that but havent marked it up yet so couldnt really comment!was going to fill up the bolt holes with weld and work from there.if it will mount in 3 places its worth having a go!
Any ideas about the spacing though!

 

[balidey]

!was going to fill up the bolt holes with weld and work from there.if it will mount in 3 places its worth having a go!

No, I don't think that will work. As i said above, by the time you have removed enough metal from the centre you will not be left with much metal. Welding up holes is possible, but making 2 inches of metal out of weld is not advisable. I'll see if I can get some pics up to help explain.

EDIT:
poor pic i know, but hopefully this shows the problem....

 

[soozukisteve]

Just photoshopped the scanned bracket ,from earlier in the thread ,up to size and i see what you mean.i dont mind the work involved to add to the bracket but might just end up getting a local machining shop to make them as my spare time will be taken up reconditioning/preparing and spraying the calipers and mounts.Im going yellow with them which should stand out well behind new alloys!
if i get new brackets made up,do they need to be 6mm in thickness?
How far through are you with the conversion and have you come across any other nasty suprises?