Page 8 of 17

Re: 7161 Chassis restoration

PostPosted: Mon Jun 15, 2020 10:37 am
by eric
And onto the Brake booster/servo.

I think they all look like this, shite....
Image

I have given it a good scrub down

Image

I was going to take it off and undid the two nuts top and bottom behind the pedal, they were tough but not as bad as folk said it loosened then with horror I saw the two other bolts top right and top left. Christ there is no way I am reaching them so I have just put the nuts back on the 2 I did and scrubbed it in situ.

Image

At least I get some use out of my POR15 as I wont be using it on my chassis now :)

Onto my steering column,
Image
Image

I have had new boots sat on the shelf for a while.

Quite a bit shorter than the originals and are very tight when at full lock, but hope they should be ok.
Image

The others were still sealed but I don't think they had much left in them.

Image

Judging by the colour of the oil, dirt was getting in somewhere.
Image

Everything looks good, nice and tight no play

Image
Image
Image

Jobs a good un
Image

Once done on the other side (just need to cut a head onto the clamp), I will refill from the middle section with 0.3 of a pint of gear oil 90w.
Image

Re: 7161 Chassis restoration

PostPosted: Mon Jun 15, 2020 2:44 pm
by cis6409
Great going nice one! , have to do the same jobs on mine to with the brake servo etc. Good to know about the bolts to!

Re: 7161 Chassis restoration

PostPosted: Mon Jun 15, 2020 5:51 pm
by Rissy
Well worth persevering with your servo. Mine looked somewhat like yours. I completely removed it (a job easier done when you have the fuel tank out, but not necessary), scrubbed it up off the car so it looked like yours now. Then i was going to paint it up nice before putting back. But then i decided to do a functionality check on it first (using my Dyson - other vacuum cleaner brands are available). Basically, it was shagged. It was leaking badly and holding no vacuum what so ever. I replaced with a new servo.

Now i've tested my car with a known good vacuum assist system, I can tell you in 11yrs of ownership, i've clearly been working the car without any servo assistance at all! What a difference it makes having that!

On top of that, upon removing the master cylinder from the servo, I realised it was starting to leak, not badly....yet, but weeping none the less. If I had left it and not realised, then it would have started filling my shagged servo with brake fluid until the next step is it leaking all over the chassis. Lucky for me, my chassis has never experienced brake fluid from either the clutch or the brake system before, so it would be a shame to let it experience it now during its old retirement years. That's a much bigger job to fix compared to removing a few bolts on the servo bracket.

So yeah. Well worth persevering.

Re: 7161 Chassis restoration

PostPosted: Mon Jun 15, 2020 6:44 pm
by eric
Thanks Rissy,

What was the test just vacuum it and see if it holds ? I just googled but most of them involved starting the engine :(

I haven't noticed bad braking but I drive it like an old lady.

Re: 7161 Chassis restoration

PostPosted: Mon Jun 15, 2020 8:10 pm
by gary290
i have to back what Rizzy has said, mine looked like that as well, after all the testing on the car it appeared to be working but i couldn't accept the rubbish brakes any longer, a new servo is not cheap but it's the best thing i've done so far, the brakes have been transformed even before doing anything else to the system (which is in a poor state), do the master and clutch master as well then you won't need to touch it for a long time,
all the best with your build

Re: 7161 Chassis restoration

PostPosted: Mon Jun 15, 2020 8:51 pm
by Rissy
eric wrote:Thanks Rissy,

What was the test just vacuum it and see if it holds ? I just googled but most of them involved starting the engine :(

I haven't noticed bad braking but I drive it like an old lady.


I just simulated the vacuum from the engine by attaching the vacuum cleaner to the non-return vac line connection on the servo. Simulating the pushing of the brake pedal by depressing the plunger "rod", you should be able to determine a noticable difference in required effort in pushing the rod comparing when there is a vacuum drawn on the vac line and when there isn't. In addition to this, once you stop the vacuum cleaner, you should typically be able to push the rod another 1-2 times with noticed vacuum assistance until the remaining stored vacuum is "used up".

When I did my old one, I literally had air pissing in through the main seal on the output part of the plunger rod which pushes on the master cylinder. The servo held no vacuum what so ever, and there was marginal at best assistance when the vacuum cleaner was sucking on the vac line non-return valve. I bet my ass the vacuum was a lot more efficient at sucking on that servo than the PRV is, and it was bloody awful with the vacuum cleaner.
Compare that performance to that which I get with my new one.....My god! Night and day.

Thankfully, servo failures like mine are, as I understand, a rare thing. They're very basic, simple gadgets, so there's not much to go wrong. But still. Factor in 40yr old crusty dried out rubber with rusted metalwork surrounding them etc....well, not THAT surprising they fail.

It's amazing the difference. I changed out my servo and my master cylinder, and also changed my front brake calipers through having an issue with one of my original ones. Really, it's like a brand new car with regards to braking performace now. Now I really can drive the car like an old lady! :D

Re: 7161 Chassis restoration

PostPosted: Tue Jun 16, 2020 7:16 pm
by Spudmurphy
I took my car out for another test run today. The brakes are terrible. New front discs,
4 calipers rebuilt,
new brake lines front and back
System bled and the pedal is hard
The brakes will not lock up.

So everything seems to point to the servo.
The brake master cylinder was changed by a previous owner and I would guess that this was carried out a good few years back .... So it may be a 50/50 master cylinder?

So it's interesting to read this.

Re: 7161 Chassis restoration

PostPosted: Tue Jun 16, 2020 9:21 pm
by andys
Kevin
if they are new discs and pads all round they will be very crap until they are bedded in. Once they are bedded they will be just crap.

I think the servos can be just weak, mine is and it doesnt leak. possibly the diaphram hardening over age or because they are not used for 30 odd years

Re: 7161 Chassis restoration

PostPosted: Tue Jun 16, 2020 10:02 pm
by Spudmurphy
Andy - I wish I could drive one to compare - but honestly for the last 20 years all I have driven is a 1979 Ford, an 83 Fiat, a 2004 Fiat, and now a 2007 Renault. All these cars , with only drum brakes on the back were twice as good as the DeLorean.
I take your point regarding bedding in , but having changed brakes on cars over the last 40 years , honestly, I think these brakes are bad.
I'll put it in for the mOT on Friday and see what the rolling road says.
(My legs aren't whimpy either! lol)

I'm not going to take this thread off the rails, but post a new one as I have more photos and more questions to ask.

PS.
In one of the BTTF films Marty drives along the road where the housing estate is and brakes really hard , the wheels screech and one wheel even tucks up, under load . What I'd give for mine to do that!

Re: 7161 Chassis restoration

PostPosted: Tue Jun 16, 2020 10:27 pm
by andys
Kevin
I have been trying to improve my brakes for the last 4 years and convinced it is the servo. Done loads to try and improve things. 4 pot princess calipers. red stuff, green stuff, new braided hoses, new master cylinder. Even played with an electric vacuum pump from a modern car. Strangly they just seem to be getting a bit better now, possibly the diaphram loosening up.

I have bought a couple of modern dual diaphram servo units off ebay but lack of room means they physically dont fit. The current servo is a 7 inch single diaphram unit and most moderm cars are 8-11 inch.

hang in there buddy, if owning one of these cars was easy everyone would have one.