Fitting 4W disc brakes? Other wheels?

Discuss with fans and owners of the most luxurious aircooled sedan/wagon that VW ever made, the VW 411/412. Official forum of Tom's Type 4 Corner.
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func412
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Post by func412 » Thu May 18, 2006 10:38 am

Today was the first test day. I made few brakings and first feeligs are good... but there is still some work to do.

The brake pedal felt like it used to do earlier... soft and flexible, like rubberball. Like there was some air in the system. Is there some special tricks to remove air from 412 brake system? I have removed original brake pressure regulator away.

Well I think the reason for this symptom may be also old brake rubberhoses, which are at least 19 years old. I know that for sure, because this car has been not used since it had engine failure in 1986 and the car was removed from register. They seem to be in good condition even though those may be as well original ones =) Anyway, these will be replaced by new ones.

The brake balance needs some adjusting also, but let´s start from the hoses first.

EDIT: I found that Volvo calipers are guite tricky to bleed, so I´ll replace the hoses and bleed the brakes more carefully in specific order (there is 8 points to bleed)

vwbill
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Post by vwbill » Fri May 19, 2006 1:33 am

Hey, good first test!! I started with no feel! I did replace my rubber hoses
because I had heard they could be a issue. You said you toke out the proportioning valve, will you still need some kind of valve to control the front to rear pressure? Did you bleed the brake by yourself or with help pressing the pedal? I did my brakes with a hand vacuum pump on each bleeder valve then pumped the pedal and use a board to wedge against the pedal and the seat bar or seat and then would put a hose in bottle and just crack the bleeder open and then repeat for that valve and then do the rest? Sounds like you are moving along great! Just sounds like some more bleeder! Thanks for the post! bill

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raygreenwood
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Post by raygreenwood » Fri May 19, 2006 7:33 am

The proportioning valve has been a source of debate. Its funny....most of the wagons on this continent did not come with proportioning valves. Perhaps they figured that most people would drive with the rear cargo area loaded and that would prevent the forward enertial shift that threatens to bring the weight off the rear wheels....causing the brakes to lock early in hard or panic stopping.

It really is not a "proportioning" valve per-se. It is a limiter. The rear brakes recieve the pressure just like normal. When said pressure reaches something like 600+ psi (can't remember the exact amount)...the plunger snaps closed. You still have pressure on teh line as it is like a "line lock".....until you release the pedal. But...it does not increase past the lock point. It is designed to keep the rear wheels from locking on hard stopping on wet pavement...or in panic stops. Having owned and driven two doors, four doors and wagons in all environments.....I can tell you that the valve does work as intended though its actual need for operation is quite rare.
You can remove it and 99.9% of the time you would not need it.

One thing that has always interested me.....is timing of brake fluid pulses. In teh master cylinder, teh primary piston is the outer one (if memory serves). The pedal starts moving that one first. When a certain amount of pressure on teh spring that is on the bottom of this piston is reached....it begins moving the lower piston.
I did some experimenting a few years back...but ran out of time before I got too far.
In theory...you could reverse the back to front lines if the fluid volumes are acceptable. This way....the rear brake begins slightly in advance...to keep teh inertial shift from getting out of hand. Then....by putting in a re calculated spring on teh bottom of the first piston...you could start the front brake quickly afterward. Ray

farmer
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Post by farmer » Sun May 21, 2006 5:56 pm

With regards to rear shock options, you might want to take a look at 79 - 89 T3 front shocks. That´s what I have mounted on my 412 Variant (Red Koni´s) They almost fit right in, and are valved quite ok for a heavy car like that. The rear of the 412 is about the same as the weight on the front axle on the T3, empty. (About 740 kg.)
They control the car nicely.
T.

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Wally
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Post by Wally » Sun May 21, 2006 7:10 pm

farmer wrote: They almost fit right in, ...
Thats usually what scares me :lol:
Thanks for the tip Torben! Much appriciated.

On a different note:
I _might_ have an idea after all on how to bolt a 944 rear disk set to the 412 rear axel... :roll:
When I have confirmed it was one of my lesser idea's, I won't embarress myself any further, otherwise I will make a new post.

Walter
T4T: Type 4 Turbo engine, under construction

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func412
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Post by func412 » Mon May 22, 2006 12:01 am

Wally wrote:
farmer wrote: They almost fit right in, ...
I _might_ have an idea after all on how to bolt a 944 rear disk set to the 412 rear axel...
Interesting, keep us informed!

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func412
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Post by func412 » Mon Jun 05, 2006 8:14 am

I definitely need new brake master cylinder. There is no power brakes in my 412, so is there any bigger (bolt on) brake masters available, which are attached in place like the original is (from the side of MC). Or do I have to use my imagination again =)

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raygreenwood
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Post by raygreenwood » Mon Jun 05, 2006 8:24 am

There is nothing that I know of that bolts up like the 411/412 cylinder.....but if there were...it would be in the Vanagon. The vanagon clutch master can be very easily dropped right into the 412 with only a new bracket. A single look at it will show you teh way. I have never looked at the vanagon brake master. Perhaps it would be worth it.

On that note...here is something that does work....and takes but minor facbrication. The 21mm bus master cylinder...can be installed.

Look in the trunk near the brake fluid reservoir. See the boss...or pressed area in the body...about 1.75" in diameter? That is where they punched out the hole for the pushrod to run the power brake unit that usually sat in the trunk. You need to cut that out......and drill two holes...and you can bolt teh 21mm bus master to it. You will then need to fabricate a pushrod and fulcrum to connect to the pedal. But compared to the fabrication you have already done to the brakes...That would be minor!
I have not decided wether it would be better to stub off the two existing fluid ports under teh dash and use teh cylinder mounted reservoir like on teh bus...or try and loop the lines back through the trunk. The bus cylinder should have plenty of reserve and is easy to get. Ray

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func412
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Post by func412 » Sun Jul 30, 2006 12:34 pm

We finally got brakes working and tested those in 6 hour endurance race. I must say the work was worth it. The brakes had good balance and power and there was no overheating broblems. I installed volvo 240 brake master, which solved the problem. It really wasn´t a bolt on solution.

We drived over 4 hours until I heard strange noise from engine. We had to give up from second position. In the pit we saw that the bolts were missing from dellorto air filters. There was some luck those got not inside the engine, but those stuck inside the carbs. Image

If you like to see videos, download these files into your computer from Rymstigers racing team website.

http://www.rymstigers.fi/kuvat/mov/urho061.mpg
http://www.rymstigers.fi/kuvat/mov/urho062.mpg
http://www.rymstigers.fi/kuvat/mov/urho063.mpg

Here´s some pictures:

http://jleskinen.net/urhon_ajot2006/

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Wally
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Post by Wally » Sun Jul 30, 2006 1:04 pm

Excellent drive and thanks a lot for posting these pictures/video's

I really like some of those pictures!

Thanks man!
T4T: Type 4 Turbo engine, under construction

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Wally
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Post by Wally » Sat Aug 05, 2006 3:49 pm

What engine is in your track-412 anyways?
T4T: Type 4 Turbo engine, under construction

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func412
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Post by func412 » Wed Aug 09, 2006 3:43 pm

The engine is just original 1700cc (66x90) with domed pistons/Scat cam/40mm dual dellortos/headwork done for 39-34 valves/etc.

We had second race last weekend and we were slow but reliable. We were fifth this time (there were 7 cars altogether in race)

This car is not originally made for racetrack, so next we have to consentrate to lose weight and make it more stable in the corners. We are working for a bigger engine also.

Here are some stuff from the last race in "DWL" website: http://dwl.fi/shows/kemora/

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Wally
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Post by Wally » Thu Aug 10, 2006 3:27 am

OT, but I noticed you had removed the plastic air intake all together.

Is that really benificial? Now your engine doesn't suck cool air that came over the top of the car anymore :?

http://dwl.fi/shows/kemora/slides/kemor ... 20015.html
T4T: Type 4 Turbo engine, under construction

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raygreenwood
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Post by raygreenwood » Thu Aug 10, 2006 11:47 am

Yes. Thank you! It was really nice to watch your videos. It looked like great fun.
Its also nice to hear it is a 1.7. In good tune a 1.7 is a quick engine. With just a few mods and very careful build. 100hp...is not unheard of with a 1.7.
What gearbox is it? Is it the factory 004 four speed?
I had always thought that fourth was a little odd going through the "twisties"....but 2nd and 3rd gears with the final drive ratio it has ....are excellent. Ray

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func412
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Post by func412 » Thu Aug 10, 2006 3:04 pm

Wally, you are right. It isn´t very good solution indeed. I have planned to make a little bit lighter intake for fresh air, because the rear hood had too much weight and i didn´t have those rubber parts anyway. Now I saw also why the rear hoods rust so bad, because it is filled with that urethane (or whatever that weird material is) stuff.

Ray, I must say I´m not sure about the gearbox but I´m going to check it out. I have two 4 speed manual gearboxes as a spare and another is taken from this car. I replaced it with another 4 speed gerbox 2 years ago. I´m saticfied with it, but the shifter is awful.

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