Hi all

I'm a Dutch member. But guess I would get better feedback at this forum
(had some great feedback in the past, really gratefull for that )

My MOT (dutch equivelent) is comming soon. I had the car checked at the garage, and it passed all tests but one. My left rear brake isnt functioning (proparly). Btw I have the Unomanual pdf thingy, the pics are from the manual.





The spring has snapped, and has to be replaced obviously. According to the garage the "load proportioning valve" is broken/stuck, and has to be replaced. He advized to get the part at the local scrapyard.

My question actually is, how hard it is to get it out of a scrapped car and what the costs kinda are to have it put in my own car. My biggest concern is correctly disconecting the hydrolic lines.

Does anyone have any experiance with this problam? And give me some advice

Thanks in advance, this forum has been really helpfull in the past.

i think mines on its way out soon, making an awfull noise.

From what i remember, when i had a look about a month ago it didnt look too hard to sort out with the rear axel jacked up. With regards to teh hydraulic lines, should be fine as long as you bleed the system properly

Sorry i cant be of much more help, maybe Louie will consort his porter manual

Hi Nick_K81,

Sorry I didn’t say “Welcome to the forum” on your first thread.

Are you going to Zandvoort for Italian Race Festival 16&17 of June 2005

LOL Luke – I was waiting for Alex GS, Chas or Morten.

Nick_K81 said:

Its a Fiat uno 45 i.e from 1992

Click to expand...

so shouldn’t be antiskid.

I’m not so sure this spring or valve being broken would cause only one side to perform badly. It acts on the overall pressure to the rear (footbrake) circuit, not to each side independently. I’d check the Brake shoes, rear cylinders and flexi hoses. There may be more than 1 problem. Have you noticed a loss of brake fluid?


This is what I found on the valve and spring and hoses:-
https://www.fiatforum.com/gallery/showphoto.php?photo=4225&size=big&sort=1&cat=602&page=1

https://www.fiatforum.com/gallery/showphoto.php?photo=4226&size=big&sort=1&cat=602&page=1

If your scrap yards are like ours in the UK, cars pilled on top of each other, It could be difficult to remove these parts. You may find the spring you remove is bad too so try and price up a new one. Perhaps the valve will be OK with just a new spring.

The Uno handbrake is notorious for failing on the left
https://www.fiatforum.com/showthread.php?t=1819 hits the nail on the head.

Thanks for the reply's

I live near Zandvoort (like 12km) and am there every now and then with some friends. We have this old bmw 325 we thrash/drift around with... alot of fun (not on the track itself, but in the large paddock area when its clear)

Back to the subject. Yes indeed its not antiskid. My handbrake is also fairly non-existant. The power is just enough that your not able to push the car by hand. But on a hill is not enough. I havent read the link yet and will do so after posting.

I was already checking the right rear valve, but couldnt find one
The diagram explaines alot,.... there isnt one
I'm not losing any brake fluid. Atleast my brakes havent acted differently since I have the car (little over 1/2 year)
My right rear seemed to be ok, so indeed a bit wierd that the valve would be faulty if it is used by both brake cylinder's :S

The scrapyard is no problam overhere. The cars are sorted by make (i.e Fiat etc) and stand side by side. So acces is not an issue. Tools and a good jack, you can lend at the yard (so I heard). Near the scrapyard there's a Fiat dealer. So I'll first see if I can get a new spring and see if that solves anything. Just a note: I think the mechanic did check it proparly. If you would pull the control lever down manually and have someone (me) brake wouldnt he feel a differance ??

Thanks for all the great advice agian

Nick_K81 said:

...Just a note: I think the mechanic did check it proparly. If you would pull the control lever down manually and have someone (me) brake wouldnt he feel a differance ??

Click to expand...

Not sure to be honest. I thought you would need to be on a brake testing "rolling road" machine to tell if the more brake effort was being applied to the rear.

I think it would be wise to check the other components after the valve - ie Flexi Hose, Slave cylinder, Shoes and Drum. I'd imagine one of these would be bad too - perhaps the shoe adjuster or centralising spring.

Please Keep us updated

Kind Regards,

Crap.....
The fiat dealer's spare parts shop was closed till thuesday
And the scrap yard was to busy to lend anything, back thuesday as well
And the good garage where I wanted it all fitted was closed

Everything has to be in proper order before friday

It will be a close call


All the springs on the scrap cars look awfull btw. Another thing is that the arent any tyres on the cars,.. so how do you put the 65kg of weight in the back so you can realese the spring,,

The mechanic did it by hand (dodge place btw) so mayby the right rear isnt working to well either.. I cant be sure. He said it was this and that, and I first had to look it up to see what he exactly was talking about (for example I thought there would be 2 valve's )

Anywayzz... I gues I'll have to do it all on thuesday then

Nick, if you break the pipes you're screwed, well, not completely but I wouldn't envy you having to replace them. We actually nearly scrapped me having a Uno for this reason. The load preportioning valves go wrong on almost every car if you don't carry loads very often, however, unlike the uno, most are easy to sort out!

Be VERY careful removing the pipes on your car, once removed and you replace the spring, make sure you grease the whole unit fully and make sure it is fully free.

I think we used a few old sewing machines etc. for the weight but it was a few years ago, i'm sure you have some heavy things lol.

Best of luck.

I think pretty much all the important points have been made regarding Nicks post.

Yes, those valves do have a habit of seizing, or the spring goes rusty and breaks.

I haven't changed one myself, but they don't look too hard. The biggest problem is going to be getting the pipes off without breaking as Paul mentioned. All you can do is give them a few doses of WD40 or anti seize spray at various points over a couple days and hope that will loosen them off. If you're lucky they will come off, if not you might twist or bend them and will have to replace a whole brake pipe.

The problem with using a second hand brake valve from a scrapyard is that the chances are it will also be seized! Check first before paying!

There is only one proportioning valve on the Uno. All it does is reduce pressure to the rear brakes if there is little or no load being carried in the car. That probably accounts for most of the time in the average Uno, so the valve doesn't get moved much so seizes into place.

Rear brakes not working properly on one side will NOT be a problem with the valve. It's either a stuck brake shoe mechanism, or one side might have got contaminated shoes. Check the brake cylinders to make sure they aren't leaking brake fluid onto your shoes.

Best of luck, and hope you get it sorted out.

Chas

Thanks for the advice all. I found some expert help, so everything is going to be fine. We start cracking tomorrow or the day after. I'll keep you posted on the developments

Just bought a new spring, and will fastened it this evening. I've waited in buying the valve. I'll check the pipes/shoe's etc once I can have a propper look at the car, with the expert

Yeah !!

Got threw the MOT I found a guy who was kind enough to have a look for me.

It was the rear brake cylinder that was faulty. The valve was stuck but is working again.

Everything is working A ok again

Thanks for the help all !