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Firewall Cracked @ Master Cylinder!

Mhfco6

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Does anyone have a sure fire way of fixing the firewall at the clutch master cylinder. I replaced my leaking master cylinder on my 91 Ranger thinking i was going to fix my truck and then I heard the pop at the firewall. Even bent my new pushrod and broke the welded nuts for the bolts! I’ve exhausted about every avenue I’ve thought of so far.

My truck won’t even start because the safety switch isn’t getting pushed down far enough.

I’ve tried to sandwich aluminum cutouts on both sides of the firewall, but the master cylinder is plastic don’t want to break it tightening plate against it. Bronco graveyard has a fix for the FSeries and Broncos but I don’t see one for the ranger.
Post up your ideas and fixes for this!

69000
 


dvdswan

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Maybe get a 1x2x1/4" or 3/8" strip with each end a little thicker with a hole large enough for the stud and try to pull it back even with the firewall. then weld it back up. You will need to possibly put a plate on the back side of the repair.

I would find where the water leak is that started the issue though.

Cracked firewall fix | LS1GTO Forums

I know on my old K10 the clutch pedal did this, on the 85 - 91 C/Ks they reinforced the firewall with an extra plate for the hydraulic system.
 

Mhfco6

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Maybe get a 1x2x1/4" or 3/8" strip with each end a little thicker with a hole large enough for the stud and try to pull it back even with the firewall. then weld it back up. You will need to possibly put a plate on the back side of the repair.

I would find where the water leak is that started the issue though.

Cracked firewall fix | LS1GTO Forums

I know on my old K10 the clutch pedal did this, on the 85 - 91 C/Ks they reinforced the firewall with an extra plate for the hydraulic system.
This is my second time owning this truck, I decided to fix it better this time.. it’s already throwing me for a loop. I welded a new floor pan in a few years ago but for the life of my can’t find where the water is coming in. Only thing I can see is a drip line from the rear window.. even after I had the rubber seal replaced.

Keep those firewall fix idea coming!
 

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Does anyone have a sure fire way of fixing the firewall at the clutch master cylinder. I replaced my leaking master cylinder on my 91 Ranger thinking i was going to fix my truck and then I heard the pop at the firewall. Even bent my new pushrod and broke the welded nuts for the bolts! I’ve exhausted about every avenue I’ve thought of so far.

My truck won’t even start because the safety switch isn’t getting pushed down far enough.

I’ve tried to sandwich aluminum cutouts on both sides of the firewall, but the master cylinder is plastic don’t want to break it tightening plate against it. Bronco graveyard has a fix for the FSeries and Broncos but I don’t see one for the ranger.
Post up your ideas and fixes for this!

View attachment 69000
I have a 90 Ranger I use for parts. I could take a cut off wheel and cut out enough you could weld it in .
 

bobbywalter

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I just shim it with a piece of 16 gauge till I have time
 

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It's probably the cowl leaking. The firewall is two pieces thick there... You can fix it from the inside or the outside, this is kinda what that area looks like.



I removed the outside layer for that pic. This is what it looks like. Obviously a lot of stuff removed to get that far but maybe it will give you some ideas.

 

Mhfco6

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It's probably the cowl leaking. The firewall is two pieces thick there... You can fix it from the inside or the outside, this is kinda what that area looks like.



I removed the outside layer for that pic. This is what it looks like. Obviously a lot of stuff removed to get that far but maybe it will give you some ideas.

Good stuff, looks like that piece covers all 3 pedals. I’d rather not take everything in the engine bay and interior apart but might have to. That 1st pic you sent is a good representation of how that rust comes in around the booster and clutch master cylinder.

I looked with a flashlight inside the cowl but didn’t see and rust, I’ll have to take the cowl off and take a better look this time.
 

Mhfco6

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I just shim it with a piece of 16 gauge till I have time
One one the inside, or each side of the firewall? If you have done this do you have a pic?
 

Mhfco6

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I have a 90 Ranger I use for parts. I could take a cut off wheel and cut out enough you could weld it in .
I may take you up on that offer.. I will need to dig deeper and see how bad the affected area is.
 

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If you dont want to weld it, you could use a mending plate. something wide enough to grab both sides of the crack. I would place 1/8" thick steel or 3/16" thick aluminum maybe 2.5" wide, on one side and send self tapping hex screws through the other side with fender washers. You could also use 1/4" thick plate and drill/tap it for 1/4"x 20 hex bolts or machine screws.
 

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I may take you up on that offer.. I will need to dig deeper and see how bad the affected area is.
Let me know. The steering column , pedals , most of dash , tranny is already in the shop. Won't take long to yank the engine.
 

19Walt93

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We used to have problems with F series dashes cracking at the clutch master if people ignored high clutch pedal effort for too long and Ford had a reinforcement piece we would install to fix it. If you can find one I bet it would work on a Ranger if you don't want to use the offered dash piece. Regardless, I would use steel and not aluminum because dissimilar metals will corrode. And if you clutch has high pedal effort, replace it or you'll be fixing it again.
 

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I had a '91 with that problem. I put a piece of flat steel on the engine side as I recall and used longer bolts to reinforce the cracked area.
 

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I you are just going to fix what is there, I would stop drill the end of the cracks to make sure they don’t grow anymore.

If you are going to sandwich the area with more metal, I would use something to seal in between to keep water from getting trapped and causing more damage.

I would also try to find the leak source and attack that. Assuming it’s a leak that caused the problem and not just metal fatigue.
 

bobbywalter

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One one the inside, or each side of the firewall? If you have done this do you have a pic?

Not sure about pics....maybe. they were others trucks. Put shim on outside.

It is much more common on 150.
 

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