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I locked the diff to torque the retaining nuts. Crude but effective. I don't see how it's possible to lock this box in two gears simultaneously, the internal detents that slide between the shift rails prevent that and I don't like jamming hunks of metal between gears to lock it.


Old 03-10-2017, 09:52 AM
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enjoyed the thread. learned some things,

back to the FD.
I think you should replace that metal shim. It looks bent/dimpled in the pic
I think the problem is where the valve seals to the shim it can dimple and not seal properly

no sealant.

took mine apart too before sending it flowcontrol.
mine was clean also. I was a little disappointed. was hoping to find it bad.
talk with larry about the shim. great guy.

also balancing the flow out of the head is important along with max flow at WOT.
I think factory setting is 20% of the max flow the head is capable of.
larry can set it up for what ever you need.
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
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08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
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Old 03-10-2017, 11:48 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #122 (permalink)
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There's a real easy way to lock the gears from turning.

Engage a gear set with the gear selector rod like you normally would from inside the car. Remove the inspection cover on the bottom side of the transaxle, it's held on with four 13mm nuts.

Use a pry bar or big screwdriver to slide the other synchro unit slider over to engage another gear sets selector teeth so two different gear sets are engaged at the same time. This is real easy, only takes a few minutes to do, and doesn't hurt anything. All you're doing is selecting two different gear sets at the same time so the gears and shafts can't turn.

When you're done reach in there with the big screwdriver or pry bar and slide the synchro sliders back into the neutral position in between two gear sets where they are not engaged with any selector teeth.

Put the inspection cover with it's steel shift rod guide fork in the proper position back on with a new paper gasket and some kind of gasket sealer.

If the cast aluminum inspection cover mounting surface is warped or not perfectly flat possibly from being over tightened in the past a thick layer of RTV silicone gasket sealer or something similar on the paper gasket will keep it from leaking gearbox oil.
Old 03-10-2017, 11:55 AM
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Quote:
Originally Posted by T77911S View Post
enjoyed the thread. learned some things,

back to the FD.
I think you should replace that metal shim. It looks bent/dimpled in the pic
I think the problem is where the valve seals to the shim it can dimple and not seal properly

no sealant.

took mine apart too before sending it flowcontrol.
mine was clean also. I was a little disappointed. was hoping to find it bad.
talk with larry about the shim. great guy.

also balancing the flow out of the head is important along with max flow at WOT.
I think factory setting is 20% of the max flow the head is capable of.
larry can set it up for what ever you need.
Regarding the stainless steel diaphragm you're calling a "metal shim" for some reason.
I've rebuilt 4 of these crappy old cast iron things now. The original Bosch stainless steel diaphragms are polished glass smooth on both sides and they are installed dry. The replacement Salvox stainless steel diaphragms have a satin machined surface on them and Salvox says to use sealant so I always did.
I don't know why but maybe it's because the surface finish of the Salvox diaphragms is not polished glass smooth like the Bosch ones and because of that they suggest using sealant.

If you only smear a real thin coat of sealant on the two halves of the fuel head and no sealant next to the control pressure pinhole in the metal diaphram then nothing can go wrong using sealant.

This is the pinhole fuel supply orifice in the metal diaphragm that creates the control pressure circuit in the top half of the fuel head. The control pressure regulator returns fuel from the control pressure circuit faster or slower than it can be supplied through this pin hole by system fuel pressure on the bottom side and thats how control pressure is varied up and down to change the air fuel ratio.
It's just a pin hole so you have to be careful to keep sealant away from it or it could be clogged up by squeezed out sealant when bolting the fuel head back together. I'd rather use a little sealant than risk having to take all this stuff back apart if it leaks after not using sealant.

I drew a red arrow pointing at the control pressure fuel supply pin hole in a metal diaphragm. The rubber diaphragms in the aluminum lambda fuel heads don't have this pinhole and they use a different orifice for control pressure fuel supply.
Old 03-10-2017, 12:56 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #124 (permalink)
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"Use a pry bar or big screwdriver to slide the other synchro unit slider over to engage another gear sets selector teeth so two different gear sets are engaged at the same time. This is real easy, only takes a few minutes to do, and doesn't hurt anything. All you're doing is selecting two different gear sets at the same time so the gears and shafts can't turn."

I tried that. With one slider engaged how do you engage the other slider w/o moving the shift rail? The internal detents that slide between the shift rails prevent the other rail from moving when one is engaged so you can't grab two gears at once. These aren't the detents under the external caps, they are in a drilling that intersects all three rail holes in the diff housing and are held in place by roll pins in the diff housing. they can't be taken out with the gear housing in place. Or what am I missing?

On the fuel head shim- I noticed I am getting some fuel weeping out of two of the injector ports when I was checking the control pressures - that might be due to the dimpling. I think I'm going to replace it since I have it anyway, it doesn't take long.
Old 03-10-2017, 01:16 PM
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"I tried that. With one slider engaged how do you engage the other slider w/o moving the shift rail? The internal detents that slide between the shift rails prevent the other rail from moving when one is engaged so you can't grab two gears at once. These aren't the detents under the external caps, they are in a drilling that intersects all three rail holes in the diff housing and are held in place by roll pins in the diff housing. they can't be taken out with the gear housing in place. Or what am I missing?"

I don't know what you're missing. I did this around 7 to 9 years ago and I don't remember every little detail. I do remember I had absolutely no problems doing what I did and it worked perfectly.

I will say Porsche Synchro units are some of the most over engineered clunky garbage on the planet.
Borg Warner brass synchros used in Getrag transmissions are simple low cost heaven compared to them and work so much faster and smoother and are made up of less than 1/5 of the stoopid parts Porsche used.
Old 03-10-2017, 02:02 PM
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What year/type was the transmission you did?
Old 03-10-2017, 02:52 PM
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It's an '87 911 turbo 4 speed.
It was rebuilt when the previous owner had the car and I have the receipts. It works really well and I always match rev double clutch on down shifts because that's how I learned.
My first manual transmission car was a '72 BMW 2002 with totally worn out synchros back around 1980. You had to double clutch on downshifts or it would grind selector teeth. I rebuilt that one.

I removed the inspection cover with the steel fork on the inside. When it's removed it partially frees up some of the movements of the internal linkage.

Last edited by JFairman; 03-10-2017 at 03:18 PM..
Old 03-10-2017, 03:12 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #128 (permalink)
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"On the fuel head shim- I noticed I am getting some fuel weeping out of two of the injector ports when I was checking the control pressures - that might be due to the dimpling. I think I'm going to replace it since I have it anyway, it doesn't take long."

I rebuilt my aluminum fuel head because the number 4 injector would never stop spraying or leaking a little fuel. This was caused by the rubber o-rings on the control plunger cylinder that had been compromised by the ethanol in todays E10 fuel.
My fuel head is a CIS Flowtech 007 fuel head modified around 2007 to flow around 20% more fuel than a stock one when at full throttle.

Salvox says their rubber o-rings and rubber diaphragms for aluminum fuel heads are ethanol tolerant so that shouldn't be a problem again.
If you could tune to get enough fuel from CIS to run quite a bit richer all the time and especially under boost maybe you could run E85 in it. Easiest way to experiment with that might be to unplug the 12 volt supply to the WUR heater element and run it like that. It will stay way rich like during a cold start.
Old 03-10-2017, 06:10 PM
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I had some time to work on the fuel head some more. I installed the Salvox diaphram and sealed it with thinned aviation sealer. That stopped the weeping that I was seeing from #1 and #6 with a closed plate because of minor dimpling on those two ports. I bumped the system pressure to 6.8B and the boost enrichment to 2.4B. CCP is still 1.9 at 65 and WCP is 3.6.

I ran probably twenty tests to get the injector flows balanced. Rather than relying on visuals of the fuel level in the bottles I weighed the bottles on my precision scale to determine the net grams of fuel (each empty bottle weighed exactly 7.6g, pretty amazing). I set up a spreadsheet with a graph to keep track of the changes. Here is where I ended up and think I will call it good. I ran three tests here to make sure the patterns were similar. I set #2 and #5 4% higher than the avg of the others because of the higher airflow they get from the pancake manifold. I don't know if that is too much or not, I'll do plug checks once I get it running. These are at WOT, that is where flow balance is most critical.

One thing to be aware of. If you have to remove an injector line to get at the adjuster you have to do a purge to get the air out of that line before you start the test otherwise the results won't be accurate. Hook it up, push down the plate and wait until the injector is spraying continuously, empty all the bottles and start the test.

Re. the Indian head shellac that Salvox recommends. If you've ever had to remove a part that has that crap on it you will be cursing whoever invented it. I think the only thing that cuts it when dry is 1,1,1, trichlor. The aviation stuff is more forgiving because it doesn't fully dry, it's essentially thinned permatex #2.




Old 03-18-2017, 06:14 AM
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Wash laquer thinner on a rag cleans up Indian head shellac real easily.
Old 03-18-2017, 07:39 AM
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I have not found that on old (years) parts but maybe it was something else. I think that Indian head is thinned Permatex #1. I hate them both equally.
Old 03-18-2017, 07:56 AM
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I need to do half of these repairs next winter. Transmission needs gone though; third gear syncro is done.
I need to install my headers, turbo, ect. Going through the fuel head and balancing is way over my ability.
So I had a great idea. I'll drop my car off next November you can fix everything and I'll pick it up in April. You know these things always go faster the second time. Just PM me your address when you get time. Thanks Buddy
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Old 03-18-2017, 08:18 AM
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Ok, but you are behind a '76 930, an '88 monster 930 build, a '74 Norton Commando, a '70 E type, a '65 VW double cab, an '88 XR400, and a '90 F150 with a Cummins 3.9 that needs a RMS.
Old 03-18-2017, 08:35 AM
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My anxiety jumped up just reading that.
I made myself a promise in my 20's. One car project at a time. Nothing gets finished if I have more than one. And I had a lot more time then. No money, but lots a time.
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Old 03-19-2017, 08:01 AM
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The '76 930 is my buddy's, 34k miles, popped a head stud, has been sitting for over 20 years Told him I'll install some Supertec studs and go thru the brakes and fuel system but will not touch the bottom end or even replace the rings or do a valve job because it doesn't need it, if he wants that done take it somewhere else. We have yet to agree on a price.
Old 03-19-2017, 08:36 AM
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Quote:
Originally Posted by JFairman View Post
The control pressure regulator returns fuel from the control pressure circuit faster or slower than it can be supplied through this pin hole by system fuel pressure on the bottom side and thats how control pressure is varied up and down to change the air fuel ratio.
this is confusing. the control pressure does not vary. (other than the heating of the WUR).
the supply to the WUR should not change. 220ml for 1 minute I think.


I think I call it a metal shim because most don't know what its purpose is and they might not realize what the diaphragm is.
the one in the pic does not look like it is good shape to me.
they get dented at the valve seat and do not seal like they should. not a big deal other than at idle. could make for a bad idle and perhaps cause injectors to leak if the valve does not seal.
hate to see him have trouble after all he has done.


I have rebuilt a few, including an old one off a 78 Volvo (before I even new what CIS was). never used sealant, no leaks. actually reused the diaphragm.
needs to be extremely clean.
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 03-20-2017, 06:04 AM
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leakdown

Good numbers for a zero hour engine. My tester is a two gauge with an .040 orifice, both gauges read the same with it dead-headed. These were taken with 80 psi inlet. I check a little before TDC so the rings are against the bottom of the lands. Sometimes at TDC the piston will rock and that can upset the rings giving a bad reading.

#1 75 6%
#6 75 6%
#2 74 7-8%
#4 70 12%
#3 76 6%
#5 75 6%

I squirted a little WD into #4 and it went up to 76-77. That one had the highest ovality of all of them at 8-9 tenths of a thou.
Old 03-26-2017, 01:17 PM
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It's only confusing if you don't know how it all works and I do know...

Your "shim" is a disc valve pressed up against an orifice by static coil spring pressure and variable bimetalic spring pressure.
The bimetalic spring is heated by 12 volts going through a winding of resistance wire wrapped around it. Ambient engine heat also heats it a little but it's the 12 volts coming from the rear fuel pump relay that really heats it.

Quote:
Originally Posted by T77911S View Post
this is confusing. the control pressure does not vary. (other than the heating of the WUR).
the supply to the WUR should not change. 220ml for 1 minute I think.


I think I call it a metal shim because most don't know what its purpose is and they might not realize what the diaphragm is.
the one in the pic does not look like it is good shape to me.
they get dented at the valve seat and do not seal like they should. not a big deal other than at idle. could make for a bad idle and perhaps cause injectors to leak if the valve does not seal.
hate to see him have trouble after all he has done.


I have rebuilt a few, including an old one off a 78 Volvo (before I even new what CIS was). never used sealant, no leaks. actually reused the diaphragm.
needs to be extremely clean.
Old 03-26-2017, 01:59 PM
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I put two 100psi gauges on my leak down tester. One on each side of the orifice inside the body of the tester.
The tester has an air pressure regulator on the air inlet side so you can set that where you want it.
With a 100psi gauge 1 psi of air lower on the right side gauge downstream from the orifice is 1% leakdown, or if the right side gauge is 10 pounds lower then the left side gauge than it's showing 10% leakdown.

100psi works well at true TDC because the piston will stay there and not turn the crank.
At pressures lower than 100psi while the piston is somewhere between the top or bottom of the cylinder it's much easier to hold the crank from turning with a wrench on the crank pulley nut.


Quote:
Originally Posted by boosted79 View Post
Good numbers for a zero hour engine. My tester is a two gauge with an .040 orifice, both gauges read the same with it dead-headed. These were taken with 80 psi inlet. I check a little before TDC so the rings are against the bottom of the lands. Sometimes at TDC the piston will rock and that can upset the rings giving a bad reading.

#1 75 6%
#6 75 6%
#2 74 7-8%
#4 70 12%
#3 76 6%
#5 75 6%

I squirted a little WD into #4 and it went up to 76-77. That one had the highest ovality of all of them at 8-9 tenths of a thou.
Old 03-26-2017, 02:19 PM
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