funny day, rear brakes and dodgy MOT station. - Alfa Romeo Forum
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(Post Link) post #1 of 19 Old 16-09-16 Thread Starter
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funny day, rear brakes and dodgy MOT station.

after finishing making rear brake pipes for the GTV and fitting new calipers ,rear pads and flexi hoses I took her off the the MOT station (trade tyres Guildford ) for a test.


last time she failed only on rear service braking. everything else was fine.

this time after all the work, hand brake failed as well and the rears were no better...something like 36% efficiency !!! didn't make any sense whatsoever,especially as she felt absolutely fine, more than acceptable IMO..


so my mate knows the lads at Halfords Guildford well, so we took it to them to test brake effieciency and confirm that Trade tyres were indeed correct.


bottom line had we booked an MOT there it would have passed. 54% braking efficiency ..!!! still not great I admit but a pass non the less...and trade tyres were nearly 20% off the mark..

the moral of the story? don't assume your MOT tester has the machine calibrated correctly...


this is a particular problem with GTV's as the rear braking is poor to begin with, we have now elected to bypass the brake compensator valve as all we think it is doing is reducing rear braking in the wrong circumstance..its only designed to do this if the car is fully laden..it may be faulty and a new one is way to expensive even of you can find a PH2 one.

I assume the result will be earlier ABS activation but other than this fail to see what the downsides are!!


so plan is, bypass compensator,fit new front pads forvbelt and braces, re-bleed the system and re-adjust handbrake for optimum.

anyway MOT booked for Weds morning,it would have passed today at Halfords so I am hopeful it will go well..

GT blackline,Bilstien B12's and Eibach Anti roll bar kit,Quaife Diff,Autolusso performance pads, de-cat downpipe,hybrid turbo,stage one clutch,autolusso re-map, swirl flap and egr delete, leon cupra front splitter,novitec light covers,simone racing gear knob.

Last edited by paul.o; 23-09-16 at 19:56.
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The brake compensator valve fitted to facelift phase 1 and early phase 2 cars is pressure sensitive not load sensitive like the early ones which had an arm operated by the rear suspension. A while back I had a similar issue. Handbrake passed. Service brake failed. Bypassed the compensator ( they were not available new at the time) and it passed and the brakes felt better now the rears were doing something. The side affect was a slow pulsating from the ABS during soft braking. I managed to find a second hand compensator a few months back and fitted it. New ones are available again from EB Spares at 190 a pop.
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When I see you at the breakfast meet I want to talk to you about this. I had problems with my rear brakes just over a month ago at MOT time. It was only after going for a drive and putting some serious heat in them that it passed.
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(Post Link) post #4 of 19 Old 16-09-16 Thread Starter
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cheers for the replies gents..

I understand the PH2 compensator is pressure sensitive but don't quite understand the mechanism by which it ''knows'' the vehicle is fully laden...is there a yaw sensor anywhere on the car? or does it just reduce pressure to the rears incrementally based on a the force of the front braking..? if so its a bit random!! as it does not take into account a full boot,or passengers .

old system was simple but much more 'elegant'' IMO. I am sure by phase3 with the addition of VDC, the whole thing works well, but the PH2 system seems ''poor''


anyway, it seems pointless,bypassing seems like the best option really... especially as it costs 190 to buy a new one, not paying that for something that has minimal impact on braking and is potentially just another problem. I suspect this is why GTV's have such a poor rear braking action.

will let you know how it turns out but the plan is to fit a 3 way union to the brake pipe from the front of the car to the O/S and N/S rear and blank off the one from the ABS.

James, I am glad you passed but not sure how cooking the brakes would resolve the issue, if anything you would get fade, unless you ''re-bedded'' in your pads all that I can see happening is that you boil your fluid ..


not doubting you fella, just curious to understand the mechanism by which this would work...and how it would improve braking action to the rear..and thus helping me to work out what is happening and devise a solution that doesn't involve taking bits off the car.


we'll have a good chat about about it on the 8th, collective knowledge always helps!!!


will let you know how the brake re-plumb goes
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I don't really understand it either. It was the (well known Alfa) garage's idea and they did it. I'll explain when I see you it's easier!
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cheers for the replies gents..

I understand the PH2 compensator is pressure sensitive but don't quite understand the mechanism by which it ''knows'' the vehicle is fully laden...is there a yaw sensor anywhere on the car? or does it just reduce pressure to the rears incrementally based on a the force of the front braking..? if so its a bit random!! as it does not take into account a full boot,or passengers .

old system was simple but much more 'elegant'' IMO. I am sure by phase3 with the addition of VDC, the whole thing works well, but the PH2 system seems ''poor''


anyway, it seems pointless,bypassing seems like the best option really... especially as it costs 190 to buy a new one, not paying that for something that has minimal impact on braking and is potentially just another problem. I suspect this is why GTV's have such a poor rear braking action.




will let you know how the brake re-plumb goes
It just reduces pressure at a preset pressure, it's as basic as that. Bear in mind the braking system is cross linked.
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(Post Link) post #7 of 19 Old 17-09-16 Thread Starter
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ok, got ya..

if its faulty then,as i imagine it would be after 18 years it is either stuck in position or in some other way reducing braking to the rear...which is of course its job!

but not all the time.

re the heat thng james, looking forward to hearing the logic behind it..


cheers


joe
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. New ones are available again from EB Spares at 190 a pop.
Just called them and unfortunately they haven't got stock, they couldn't remember having them recently either and probably won't be able to get them again.

Just out of interest has anyone converted their car to the lever type compensator (think fitted to the really early cars)?
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Bugger. Before I found a good used one, I bought 2 compensator valves for a fiat barchetta for 15 each new. The barchetta has one in each rear brake line and thinking a spider is a similar weight on the back thought they could work. Never got round to trying them tho yet.
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(Post Link) post #10 of 19 Old 21-09-16 Thread Starter
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Was going to try that wal... but after getting the compensator off the car (again) and testing the flow through with a compressor and some made up short unions to 3/16 pipe it seems its working.

So my theory is this...air in the system after our pipe replacement coupled with naturally poor rear brakes led to MOT tester stamping on brakes to test rears. This causes the compensator to engage. being the pressure sensitive ph2 version it resulted in further reduced rear braking.

Consequence is MOT fail.

Its in tomorrow and when it passes I plan to take if for a good run and then sell it.

FYI I will buy another GTV and expect the same issues. A conversion to the earlier mechanical valve makes complete sense as I don't think the PH2 version is very good due to the fact it isn't adjusted in response to how the car is laden. Not good really as a fully laden car and wet conditions won't end well.

The other thing I would do is drilled grooved discs all round and ebc yellow stuff front and rear...and probably performance fluid..

That should bring the GTV brakes up to modern standards.

Its been a learning curve on this car ...

I have learnt 3 things

1) I love the GTV especially the TS.

2 ) don't underestimate what may be required to get the car right...I paid peanuts but it owes me a fair bit now in both time and money.

3) even fully working stock brakes are below par on this car..

Love the drive though and very surprised that 155 horse can be so much fun!!!

May even keep it if she proves reliable. Either way all being well I am off to Devon this weekend and will park up the GT and take the GTV.

After 4 years of being garaged she deserves a good run...:-)
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Did it pass in the end Joey?

I know I'm in for a world of pain with my rear brakes when I finally start to put things back on the car although to be honest I've only ever driven the car about 1/2 mile since I bought it!! Will be giving it a fighting chance though by rebuilding the calipers and will be making new brake pipes plus cleaning everything up. Just pains me I've got to put a 20 year old compensator back on when everything else will be reconditioned.

Like your thinking by the way Danny on the Barchetta idea but I'll give mine a go before I start going too radical (fingers crossed), as an aside do you still have a few parts from Ph 1 916's for sale?
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(Post Link) post #12 of 19 Old 22-09-16 Thread Starter
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well....


brakes passed..

rear lower supension control arms didn't ..!!!

annoying as on the previuos 3 ..yes 3 MOT's /re-tests it only had brake advisories..absolutely no consistency at all with these MOT tests..makes you wonder really.

anyway powerflex PFR1-712 on order, 37.63 on ebay..as that is the only remaining issue I expect this will see it through with no advisories.

brakes were 4% better thn last time with 58% overall, but still only 9% of that on the rears...It seems GTV's just have sh*t brakes TBH as it has new rear calipers, pads,flexi hoses ,brake lines... and has been thoroughly bled.



will still make the hamps surrey meet on the 8th with it but this car has been ''one of those ones'' great little engine with less than 70k on the clock and it pulls and handles really well.. when I sell it someone will be getting a peach of a car... but it has required far more than I expected it would...
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Like your thinking by the way Danny on the Barchetta idea but I'll give mine a go before I start going too radical (fingers crossed), as an aside do you still have a few parts from Ph 1 916's for sale?
Keeping most ph1 stuff for mine. Still got lots of Ph2 tho. You after anything in particular. I know someone who is breaking Ph1 GTV.
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well....

brakes passed..

will still make the hamps surrey meet on the 8th :
That's good and bad news but at least the bushes won't be too bad to do. I'll see you on the 8th at the Hampshire meet, be interested to chat. (I'll be in the black 159 SW)
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Keeping most ph1 stuff for mine. Still got lots of Ph2 tho. You after anything in particular. I know someone who is breaking Ph1 GTV.
I'll drop you a PM later today or tomorrow, its just a few bits and pieces.
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(Post Link) post #16 of 19 Old 27-09-16 Thread Starter
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I am happy to report after whathas been an emotional and testing time with this car she went through the MOT re-test today and passed with no advisories....

I ma very pleased to have saved this one from alfa heaven..


work carried out..

cambelt
water pump
stat
aux belt
tensioners and idlers
full service
new rear pads and calipers
new front pads
rear flexi braske lines
obviiously fresh fluid
new coolant
new copper brake pipes
replaced pepperpots with teledials and 10mm spacers
fixed sunroof
fixed battery drain ( radio issue) and fitted new BT radio
new battery
lower wishbones
painted corroded mirror bases and replaced broken O/S one.
fixed airbag light and soldered cables under seat so it does not come on again.
cleaned Maf and ICV
new rocker cover gasket
polybushed rear lower arm inner bushes
re-coloured black leather interior, it looks great!
cleaned soft touch crap off dash.
replaced gear stick gaitor woth new
painted front calipers red and added AR decals
new bonnet and boot badges
new 2.0 T spark decal on the boot lid.


I think she looks good..!!!


will soon be up for sale,

98 reg with 69k on the clock which will go up as I am going to enjoy her for a week or two..

1750 to a forum member, I do not think there is a more mechanically sound one for the money...I have done the works on this car, but have now had a change of heart and decided to keep my GT.

only a few hundred quid away from being cosmentically perfect as well...she is a solid 7.5 out of 10 as it is, wouldn't take much for that to be a 10!
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And here she is ..
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Paint her red and you've got a deal...
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I know the green is not everyones cuppa..

If she were in the same condition and mileage in red the price would be 2500..!!!

:-)
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