CAD drawing of Uno Turbo / Tipo rear caliper adapter

Non-engine, eg: aerodynamics, gearboxes, brakes, suspension
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NickRP
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CAD drawing of Uno Turbo / Tipo rear caliper adapter

Post by NickRP »

Hello all,

I need to install rear disk brakes to a Yugo, which shares the same or very similar rear suspension as F-127, F-128, Ritmo, Regata etc.

Fiat Uno Turbo rear disk brakes are a straight fit (including caliper assembly carrier plates, that match exactly the bolt pattern on F-128 hub carriers), but they are nowadays very hard to find, and way too often calipers are in bad conditions (i.e. hand brake mechanism seized, or even broken).

I plan to use Tipo rear calipers and 227mm dia F-128 disks. I need to have the carrier plates manufactured (laser cut). Machine shop asks for a CAD drawing, which I am supposed to prepare. However, it would be of great help if someone already has a drawing that I could start with, where bolt pattern on hub carrier and caliper bracket shown, as well as the angle between line connecting centers of caliper bracket bolts and vertical axis ("tilt").

Fabrication will be done from 7mm thick mild steel plate. Yugo wheel bearings will be retained, but spacers will be inserted between disks and hubs to give the correct offset. An alternative would be to use Uno Turbo rear wheel bearing assembly, which already has the correct offset built into it.

Any input is appreciated.
GC_98
Brooky

Re: CAD drawing of Uno Turbo / Tipo rear caliper adapter

Post by Brooky »

A similar mod is popular on the centos,

The uno rear brakes bolt on using the exsisting uno caliper mount, and yes there 227mm discs

But most people go for 240mm rear discs(same as the front discs on a cinq/seicento) and Punto GT rear calipers, with a custom made mount.

Im currently working on a drawing to get a heap of these mounts cut out.
Julian
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Re: CAD drawing of Uno Turbo / Tipo rear caliper adapter

Post by Julian »

My personal recommendation on this would be to use the system fitted to the rear of the X1/9 - it is less aggressive than the swap you are talking about and more suitable to a small, light hatchback and should just bolt on without the need for an adaptor since they use the original 128 hubs. Fitting those calipers to the back ends of 'centos may be "popular" but it has also resulted in a significant percentage either being converted back of destroyed as the result of the rear brakes locking at the slightest provocation (with good front brakes on a 'cento, under heavy braking the rear will start to steer the wrong way, instead of turning the front wheels you start turning the whole car "on" the front wheels - the only thing stopping this is a degree of grip from the rear end and rear wheels that lock up that easily are not the answer).

If you are going down this route it is vital that you have a brake bias valve fitted to limit the rear braking force.

Sorry I can't help on the drawing you've asked for.
kowal
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Re: CAD drawing of Uno Turbo / Tipo rear caliper adapter

Post by kowal »

I don't know how much this can help you but quite a good drawing used to make a similar modification in a Lada Samara (non vented discs 239 mm 4*98), using front calippers from the Samara. The below picture shows it all. It's not autocad but still a step forward:) I guess finding a Samara calipper in UK is not an easy issue but probably some Fiat calippers also will fit as Samara has almost identical brake pads as Uno Turbo (since there are no Ferodo DS pads for Samara I use those for Uno Turbo - just have to cut them a bit).

Image

I have also some photos documenting the whole change from drums to brake discs if anybody is interested.
GC_128
Brooky

Re: CAD drawing of Uno Turbo / Tipo rear caliper adapter

Post by Brooky »

Julain: Quite a lot of people have done the conversion, and so far, no downsides,and no reported incedents with them locking up the rears and causing problems, i dont think anybody has fitted a bias valve(except a couple who race or rally)
Julian
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Re: CAD drawing of Uno Turbo / Tipo rear caliper adapter

Post by Julian »

And I have the complete opposite from evidence - a lot of it comes down to people lowering the car which upsets the built-in bias valve. I know it is popular but every single person I've talked to (until now) has converted back again afterwards. I think we are straying a little off-topic though. If you want to discuss the matter further drop me an email and I will happily continue there.
Guy Croft
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Re: CAD drawing of Uno Turbo / Tipo rear caliper adapter

Post by Guy Croft »

I won't accept argument as to whether brake bias is a good or unnecessary thing on this race engine website.

I am 100% with Julian on this.

Nobody with any sense or knowledge of racecar engineeering would run a modified/tuned/competition car without controllable brake bias, be a proportioning valve at the driver's fingertips or a twin master cylinders with balance bar adjustment on the brake actuator. This applies to modified cars where the weight distribution has been altered, the vehicle lowered, the brakes altered etc etc et alia. Of course there are plenty of folks who say 'oh, I never bothered with that' a vein that runs thru many threads on forums. Not here.

I can assert categorically from personal experience of race car prep and driving that too much braking at the rear end of a front-engined vehicle is EXTREMELY DANGEROUS. How much do you need? In the dry you typically need 75% front, 25% rear and in the wet nearer 50-50. Anything over 50 rear in dry conditions will lock up the back end and spin the car instantly under emergency braking. If you rely on the factory valve you are asking for trouble. As I said, this is a race engine website.

Now, back onto Nick's request please.

GC
myte128
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Re: CAD drawing of Uno Turbo / Tipo rear caliper adapter

Post by myte128 »

PM sent.

Scott.
thank you, Scott.
NickRP
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Re: CAD drawing of Uno Turbo / Tipo rear caliper adapter

Post by NickRP »

Thank you for all the input and tips.

The single reason I prefer newer (e.g. Tipo/Tempa etc) type setup is the improved caliper "slider" design, which are lubed and sealed. Furthermore, it is quite easy to use original F-128/Yugo hand brake cable, when the calipers are turned up-side down (and swapped left to right and vice versa).

Of course, brake bias is going to be adjustable.

Looking forward to receiving Scott's drawing.

Thanks,
Nikola
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