Corvair DiagramCorvair Photo
Corvair Center
home forum corvairs calendar links Corvair Podcast
California Corvairs
Clarks Corvair
Clarks Corvair
“CORSA"



Chevy Corvair License Plate
Chevy Corvair Chrome Wheel
Corvair Center Forum :  Corvair Center Phorum The fastest message board... ever.
Corvair Center 
Rear brakes locking up
Posted by: Dazanz ()
Date: November 03, 2017 08:44PM

When I brake hard in my 65 Corsa turbo the rear wheels lock up but the front don't. It has had new shoes/cylinders/hoses and dual master cylinder added a couple of years ago. Is this normal or should I replace the bias valve if it has one.

Also I added a new free flowing muffler and want to adjust the idle mixture.
Do I wind it out until the engine changes revs then wind in 1/2 a turn.

Thanks for any advice.
Daren

Options: ReplyQuote
Re: Rear brakes locking up
Posted by: MattNall ()
Date: November 03, 2017 08:53PM

Rears lock up because fronts are not working! Majority of weight is in the rear of the VAIR...


Why re-adjust idle mixture? Idling rough? Muffler would have no effect...


Normal way is

1 Engine warmed up... Chokes fully opened..

2 Engine idling.....in DRIVE if a PG

3 Back out CCW until engine is SMOOTH on that side.... Then do the same to the other side.

4 NOW turn screw CW / IN until engine misses / gets rough on that side.... then back out CCW 1/2 turn....Then do same to other side..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

Options: ReplyQuote
Re: Rear brakes locking up
Posted by: Dazanz ()
Date: November 03, 2017 09:38PM

It was idling high and then stalling intermittently but then it started not idling at all and then I noticed the 13 mm nut that holds the carb on was loose so it had a air leak. I tightened the nut and instantly it idled nice but I had already played with the mixture screw.

Sorry it's a turbo so does the same apply as if it's two carb to adjust mixture.

Also you said front brakes not working, are you saying my front brakes have a problem. I think it always locked up nicely on all 4 wheels till recently

Thank you

Options: ReplyQuote
Re: Rear brakes locking up
Posted by: MattNall ()
Date: November 03, 2017 10:07PM

YES.... everything is the same... Just one carb..

If all 4 used to lock... then the fronts are not working...

Get on a sandy / gravel road and test...





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo




Edited 1 time(s). Last edit at 11/03/2017 10:28PM by MattNall.

Options: ReplyQuote
Re: Rear brakes locking up
Posted by: CoCoCo ()
Date: November 04, 2017 12:02AM

Dad's '65 Turbo did (does?) the same thing under the same circumstances.
When driving and stopping normally, all seems well and the car stops strong. But hit the pedal quickly and the rears just lock up uncontrollably. Way too easy in fact.
My '66 convertible never did this and had very well balanced brakes. Very strong and stable too, but with none of the funny business when you have to hit the pedal quickly.
Even a hard push will not lock them up prematurely. It has to be a quick stab.

Stock single master in this case. Did it through many adjustments, many changed parts, always in good condition (we were both avid tinkerers with the brakes) and it never really changed that I could detect.
About the only thing I can think of that we did not do was to change the size of the rear wheel (or front wheel for that matter) wheel cylinders to see if they were causing any trouble.

Were there any differences between '65 and '66 cars with regard to the brakes?

Good luck with yours Dazanz. Sorry for the long-winded sequé.

Paul

Options: ReplyQuote
Re: Rear brakes locking up
Posted by: Chris Lampe ()
Date: November 04, 2017 01:25AM

MattNall Wrote:
-------------------------------------------------------
>
> If all 4 used to lock... then the fronts are not
> working...
>
> Get on a sandy / gravel road and test...


To expand on what Matt's saying;

Sandy/gravel road brake balance test,

1 - Find a suitable sand/gravel surface
2 - Accelerate to about 15mph
3 - Stomp the brake hard
4 - When car comes to stop, shut off car and get out and inspect the pile of sand/gravel in front of each tire, each pile should be approximately of equal size, if no pile or much smaller pile you found your non working or less effective brake.

Chris
Rowlett, Tx
NTCA - North Texas Corvair Association
CORSA
'64 Monza 'vert

Options: ReplyQuote
Re: Rear brakes locking up
Posted by: joelsplace ()
Date: November 04, 2017 04:12AM

I had a '66 that locked the fronts after replacing shoes cylinders and hoses. Rears weren't working. It ended up being bad new brake shoes. The lining just didn't work.

Options: ReplyQuote
Re: Rear brakes locking up
Posted by: vairmech ()
Date: November 04, 2017 04:18AM

2 notes. The brake testing mentioned above works but I do it at 5 mph. That way you don't slide over your marks you just made and you can measure the distance the tires slide. We road racers actually bore out the front wheel cylinders to 15/16" or 1" to combat rear wheel lock up. I have done the 15/16" for the street and I really like that combo. BTW, there is NO proportioning valve on any Corvair.

As far as the turbo Carter carb idle mixture adjustment, the needle adjustment range is 5/8-3/4 of a turn out from bottom. Any more or less and the engine will not run. If the engine runs outside of this range then there is something wrong somewhere.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Options: ReplyQuote


Sorry, only registered users may post in this forum.
This forum powered by Phorum.