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Author Topic: Firewall Clearance  (Read 577 times)

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Offline zhandyside

Firewall Clearance
« on: June 08, 2020, 12:50:02 PM »
We started to install our new repro tub on our 3A this weekend and we seem to have a clearance issue between the firewall and the accelerator pedal linkage on the back of the block. Would anyone be able to give me rough idea of how much clearance there should be between the firewall and the back of the block?

The linkage is interfering with the flat part of the firewall and the area where the floor/firewall seam. The body is pretty much flush with the rear cross member and i'm fairly certain the engine is installed correctly. Currently when I measure from the back of the block to the firewall I have around 3/4" of clearance.
1951 CJ3A - Restomod in progress

Offline athawk11

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Re: Firewall Clearance
« Reply #1 on: June 09, 2020, 12:04:54 PM »
I can't say for certain what the clearance is, but it is very tight.  So tight in fact that it's nearly impossible to remove or install the accelerator linkage on the back of the block...if the engine and tub are both installed.

I can get you a measurement tonight if someone else can't get it for you sooner.
2-1949 CJ3As
1-1946 CJ2A

Offline zhandyside

Re: Firewall Clearance
« Reply #2 on: June 09, 2020, 12:54:31 PM »
Thanks! A measurement would be helpful. I think ours may be too tight, as we couldn't even get the tub aligned with the rear cross member without removing the linkage from the block.

Our didn't have an engine installed when we got it, so we have no point of reference unfortunately. I'm starting to think we may have to cut out a section of the firewall and move it back in the offending area.
1951 CJ3A - Restomod in progress

Offline aboyandhisdog

Re: Firewall Clearance
« Reply #3 on: June 09, 2020, 01:13:38 PM »
I just measured mine.  I have 1.5" measured just below the head - horizontal from the block to the vertical part of the firewall. 

Then measuring just below the accel. linkage bracket horizontal from the block to the curving part of the firewall I have 2.5". 

Now, I will add that I may have a tad more clearance than is typical because I know that where some guys are unable to reach the two top bell housing bolts, I can get to mine without too much trouble - not easy, but doable.

I'll just throw this out there for the heck of it...are you certain that the accel. bracket and linkage arm are all in the correct orientation?  The angled edge of the BRACKET should be mounted up, and the flat section of the LEVER is mounted in the down position connecting to the pedal while the round section mounts up and goes to the carb. linkage.  Of course, you would be the first guy to have ever made this mistake! ;) ;D
Tom


Offline zhandyside

Re: Firewall Clearance
« Reply #4 on: June 09, 2020, 02:36:07 PM »
I don't think we even have have that much clearance. We have maybe 3/4" from the block t the firewall just below the head.

And from all the post I've read, we did have the bracket mounted properly.

 I recall seeing a post on the CJ2A page about someone having a similar issue with a newer MD Juan body. I measured the CJ2A tub that was on our Jeep when we bought it and it appears the indent in the center of the firewall is roughly the same depth. It just seems like the firewall may be mounted too far forward in general or the tub is slightly longer than it's supposed to be.
1951 CJ3A - Restomod in progress

Offline athawk11

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Re: Firewall Clearance
« Reply #5 on: June 09, 2020, 07:14:39 PM »
Does the tub rear face sit flush with the outer face of the rear bumper/crossmember?  Are all the tub mounting bolts in frame holes, including the rubber mount pads? 

Just asking to establish a starting point for troubleshooting.
2-1949 CJ3As
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Offline zhandyside

Re: Firewall Clearance
« Reply #6 on: June 09, 2020, 07:59:48 PM »
The rear of the tub is about a 1/4" proud of the rear cross member. The tub is currently only bolted down at the rear 4 bolts with 1/8" thick pads and at the toe board gussets with 3/16" pads. The other mounting holes haven't been drilled yet, but more or less line up with the appropriate hat channels.
1951 CJ3A - Restomod in progress

Offline athawk11

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Re: Firewall Clearance
« Reply #7 on: June 10, 2020, 07:04:44 PM »
I measured 3 different Jeeps and got 3 different measurements.  I measured just below the head...straight back to the firewall.  1", 1-1/4", and 1-3/8".

My next measurement is not scientific.  I reached down with my finger and estimated the distance between the linkage and the firewall...just before the firewall ""opens up" to allow for more bell housing clearance.

CJ3A--My 1" reading from above is matched with 1/8" clearance between the linkage and the firewall.
CJ2A--My 1-1/4" reading from above is matched with 3/8" clearance between the linkage and the firewall.
CJ3A--My 1-3/8" reading from above is matched with 1/2" clearance between the linkage and the firewall.

The only Jeep where the tub has never been removed is the CJ2A.

What all this means, I can't really say.  I can suggest that the CJ2A measurement is more likely to be the original target, but you can still make it work with just 1" between the engine and the firewall.  If you currently have 3/4", I would try shifting the tub an additional 1/4" to the rear and see if you can get all the attaching points to work -vs- cutting the firewall.  If the overhang at the rear bothers you, you could remove the bumper and add some spacers.  I don't believe you'll have too much to worry about with other items that penetrate the tub ( gear shifters, brake/clutch pedals, etc. )
2-1949 CJ3As
1-1946 CJ2A

Offline locomotive2111

Re: Firewall Clearance
« Reply #8 on: June 10, 2020, 07:40:03 PM »
I am not  sure what clearance is or should be but make darn sure the accelerator linkage is properly aligned on the back of the block .If it is not installed pointing in the right direction you can not hook up the rod to the carburetor and accelerator pedal and is a major pain to change without moving the engine or the body.

Offline zhandyside

Re: Firewall Clearance
« Reply #9 on: June 10, 2020, 09:20:54 PM »
Well I did some measurements on the beat up 2A tub that came with the Jeep to compare. I think I have found the issue! It appears that the floorboard is too long at the trans tunnel area. The new tub is 1-3/8" longer in that area. It can also be seen at the dash brace. The dash brace is 1/2" longer on the new tub.

I think I can cut the spot welds and the seam and take 1" to 1.25" out of the floor and move the firewall back to gain the proper clearance. If I move the body back too much further I'll have more issues with the hat channels in the front and at the rear floor.
« Last Edit: June 10, 2020, 09:33:06 PM by zhandyside »
1951 CJ3A - Restomod in progress

Offline aboyandhisdog

Re: Firewall Clearance
« Reply #10 on: June 10, 2020, 10:26:36 PM »
I think I'd be calling the place that sold it to me and give them one of two options:  1) complete refund including shipping, or 2) Come get this tub and bring me one that fits. 

This is just wrong.  Good luck!
Tom


Offline athawk11

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Re: Firewall Clearance
« Reply #11 on: June 11, 2020, 03:18:11 PM »
I think this is what we've all grown to expect from MD Juan.  The Willys Forums are littered with threads talking about the poor workmanship and the numerous modifications required to make the tub work.  This is why I've always fixed the original tubs.  There was a time of great hope in 2013 when Rommel Juan was in a leadership role at MD Juan.  Many strides were made to improve the products.  Then he left...and all efforts to improve the products left with him.

The problem with sending the tub back is that there is a high probability that the next tub will have the same issues. It's a no win situation.  This is the problem we face when the consumer has only one choice from which to purchase a product.  MD Juan seems content to offer sub par products.  And why not...they've cornered the market.   
2-1949 CJ3As
1-1946 CJ2A

Offline aboyandhisdog

Re: Firewall Clearance
« Reply #12 on: June 11, 2020, 05:30:19 PM »
I don't know what brand tub Kaiser Willys is selling but they seem to be quite confident about the fit of their tubs and they say they are officially "Mopar Approved".  Not sure that is worth much, but it's something!  But they do say only some minor drilling is required. 

I didn't know that Rommel Juan left the company.  I always thought it was a good move on his part when he reached out to the 3A page for input.  It seemed like he really cared about putting out a good product.  He probably works for Raynor Garage Door in Denver now! ;) ;) ;D ;D
Tom


Offline SteveKfl

Re: Firewall Clearance
« Reply #13 on: June 11, 2020, 06:28:52 PM »
I thought someone said KW used MD Juan tubs.  Maybe these guys are worth consideration and/or may help you with specs???
https://www.willysoverland.com/repli-tubs
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Offline zhandyside

Re: Firewall Clearance
« Reply #14 on: June 11, 2020, 09:03:50 PM »
I thought someone said KW used MD Juan tubs.  Maybe these guys are worth consideration and/or may help you with specs???
https://www.willysoverland.com/repli-tubs

The Willys Overland repli-tubs are just reworked MD Juan tubs. Basically the upcharge is for the reworking they do. Although I've heard those aren't always perfect either.

I wish I could have found a solid original tub for our 3A but that is easier said than done in the rust belt. It looks like the firewall issue should be a relatively minor fix. Still less work than repairing our mangled rotted out 2A tub.
1951 CJ3A - Restomod in progress