ur7x

iTrader: (2)

So I'm in the middle of swapping a mint, low mile 1988 Posi rear into my peg legged 1983 Z28. And I have run into the dreaded SAE -> Metric problem

After a lot a searching of this forum I'm still left with the following questions:

Question #1
Does anyone know the fitting size (diameter and thread pitch) on the 1/4" SAE factory brake line on the 1982 & 1983 cars?

Question #2
Does anyone know the fitting size (diameter and thread pitch) on the 6mm Metric factory brake line on the 1985 and newer cars?

Question #3
Can anyone recommend an adapter to connect the two?

Question #4
Is there a different/better way than an adapter? I have read that some people re-flare the 1/4" line with the 6mm fitting but given the age and condition of these lines I'm betting this will be harder than it sounds. Others have swapped all of the SAE lines over and slave cylinder to the new axel... which is an option... but the new(er) axle and brake components are in perfect (and considerably better) condition.

sofakingdom

iTrader: (1)

Do what I did. (except my rear was about a 91 or 92)

Get the rubber hose for the later model rear. Get a little short piece of the correct metric bubble flare line to fit the block on the end of the hose. (6mm line) Bend to shape as necessary. Cut one end off and put a ¼" inverted flare nut and a 45° double flare on it. Cut off whatever is on the end of the car's ¼" line and put a new ¼" inverted flare nut and 45° double flare on that. Use a ¼" inverted flare union to join them.

ur7x

iTrader: (2)

Thanks Mr Sofacking.. Do you remember the size of the flare nut on the metric end? The reason I ask is because it looks like a really oddball size...

For the benefit of all I climbed under my car with the tread gauges and a digital caliper. Here is what I found:

A1: Male 7/16 24 TPI this is on the car (a very common SAE flare nut)
A2: Female 11mm M1.0 this is on the new diff (a very oddball flare size)
*EDIT* Correct size is 12m M1.0!
A3: This adapter looks like a good candidate: FMSI 4617
http://catalog.fmsiinc.com/item/brak...-adapter/4617?

*EDIT* NOPE that does not fit.. see below

This brings up a new question...
11mm M1.0? Did I measure that right? That is a really rare flare nut size
10mm M1.0 is common as is 11mm M1.5. Did GM pick a weird flare nut here? Maybe to prevent just such a swap?

greezemonkey

iTrader: (14)

M12x1.0 for the rear hardline

ur7x

iTrader: (2)

Thanks! Yes that makes way more sense. I triple checked the metric nut and it is in fact 12mm M1.0

Curious that FMSI would make a part that fits nothing..

This one actually fits
262800
http://www.plews-edelmann.com/hydraulic-brake-fittings/

http://www.summitracing.com/int/part...2800/overview/