54 replies to this topic

[jim.mullen]

Today's project was to cut apart that engine bay crossmember and reconfigure it so it would fit with the new tall head.


This is a shot of the x-brace. You can see it's composed of a top X and a front X all welded into one piece. It has "clevis" ends that fit between double-eared shear tabs mounted to the chassis rails, and then bolts hold it in. You can also see how it's hitting the head and not down far enough to bolt in. It's a nice triangulated piece, but it is also in the way of removing the valve cover, which is something that usually comes off every race weekend.


Here you can see it sitting on the oil fill cap. That top X has to go, or be turned into a box that surrounds the valve cover, giving room to take it off and lash the valves without removing the x-brace. Kirk and I looked at it for maybe 15 minutes before we decided that the top X should be cut, and we'd separate the mount into a front mount and a rear mount. The rear mount will get some additional bracing to tie it into the firewall area. Sort of like a "K" style strut bar on a street car.


Cutting with an .040" wheel in the trusty Makita grinder.


Also used the air die grinder with an .040" wheel.


Raw cuts....


... were gound smooth and on this leg, you can see there's a gap between the original tubes, so some welding is in order to tighten this up...


There was also a similar unwelded area on another leg...


...and some porosity in an existing weld on another leg. The porosities in a weld bead are made very clear after media blasting. All will get welded up after grinding out the bad....


Porosity ground out...


And a weld pass made to fix it up. This weld is a little "tall" and that's a hallmark of the little welder, but it's sound and strong with no porosity.

I then blasted everything again to get rid of any welding "patina" and then two coats of primer and two of topcoat. It's drying now, and I show pics of the finished front X-brace tomorrow. I know, fascinating stuff, right?

I promise it'll get more exciting when I build the oil pan and the header!

Edited by jim.mullen, 04 March 2010 - 08:57 PM.

[Buford]

Whoa.....hand control on the TIG torch.....I can't get the pedaling thing right ( keep spinning the tires!) let alone try my hand control. Way to go..........

I need lessons

[Doodson]

That looks like a B18B engine you got in there?

[firstgencrx]

Whoa.....hand control on the TIG torch.....I can't get the pedaling thing right ( keep spinning the tires!) let alone try my hand control. Way to go..........

I need lessons

That looks like a MIG pass to me. If it is, very nice and smooth. Nice work Jim!

Too bad you're not in my neck of the woods Skip. I would love to show you how to TIG.

To add a little more for Skip:

Try to set your current so when the pedal is full on, you are the hottest you want to be for what you are welding. It sounds like you have the current too high. You want to have the full range of your pedal at your disposal. If you are getting enough current at only half pedal, you're too hot.

Hey, this sounds a lot like the throttle body thread!

[jim.mullen]

That looks like a B18B engine you got in there?

D16A1 actually. The SCCA has an approved engine list for GT cars, and there are 9 Honda engine choices for the GT3 class Hondas alone! Pretty cool, pick your favorite engine family and go racing! Kirk's going with the D16A1 for this, which I think is a great choice for the GT3 class in this car. He could go all the way up to a K24 series engine for GT3 in the CRX, but the car would have to weigh almost 2200 pounds with that engine. With the smaller engine, he gets to be at 1850 pounds or so.

[jim.mullen]

That looks like a MIG pass to me. If it is, very nice and smooth. Nice work Jim!

Too bad you're not in my neck of the woods Skip. I would love to show you how to TIG.

To add a little more for Skip:

Try to set your current so when the pedal is full on, you are the hottest you want to be for what you are welding. It sounds like you have the current too high. You want to have the full range of your pedal at your disposal. If you are getting enough current at only half pedal, you're too hot.

Hey, this sounds a lot like the throttle body thread!

Yep, MIG pass with the little Miller, using a weave technique (the "Christmas tree weave" I have heard it called.) Thanks for the kind words David! As for that little hand control, I have a love-hate relationship with it. It does make TIGing out of position much easier, but it took a LOT of practice using it to get smooth. It's coarse compared to the foot control because you have to push and pull the thing (no spring return) to vary the amps. I find it unnatural. I SHOULD have switched to the foot control for that little engine mount, but I was lazy and just used the one that was hooked up at the time! Should I have admitted that?

[firstgencrx]

Yep, MIG pass with the little Miller, using a weave technique (the "Christmas tree weave" I have heard it called.) Thanks for the kind words David! As for that little hand control, I have a love-hate relationship with it. It does make TIGing out of position much easier, but it took a LOT of practice using it to get smooth. It's coarse compared to the foot control because you have to push and pull the thing (no spring return) to vary the amps. I find it unnatural. I SHOULD have switched to the foot control for that little engine mount, but I was lazy and just used the one that was hooked up at the time! Should I have admitted that?

I've never used a hand control torch. There is a lot of TIG that's done with a steady pedal. Mostly on the thick stuff. When you weld for chrome, you always do a steady pedal pass so the bead is smooth and flat. Then the re-finisher has less to do to the get things smoothed down for the chrome.

It's only when you're welding the thin stuff is when you need to pump. Otherwise you burn through. On the thin stuff, you stand on it, watch for full or near full penetration, drop the rod in the puddle (which cools the weld a bit, giving you a little more time), and just before you think you'll burn through, you back off and let things cool. Move over and do it again. Each event takes only a fraction of a second. The whole "Stacking Dimes" idea was not originally for looks, it was a simple byproduct of getting a good solid weld on the thin stuff. People seem to like the look when you make all your cooled puddles (dimes) the same size and spacing. THAT'S what takes a shit load of practice.

But you know that!

Thanks for sharing Jim.

[Doodson]

I guess Kirk would have to answer this , but why GT3 and not GTL? maybe due to the fact that he will not need to run a restrictor. I have the opportunity to see the GT3 Specialty Nissans that dominate in SCCA GT3 and I can truly say that they are FAST! These cars are hard to beat and no offence , but I dont think Kirks car would not even come close in GT3. It is lookin good though. COME BACK TO GTL!

[jim.mullen]

great welding there bud! im kinda confused trying to look at the pics tho. its like half the stuff is welded, and half the stuff is bolted and almost looks like its meant to move. is there some sort of rhyme or reason to this stuff?

I missed this post earlier so I never responded to it. Kaymo, you're right and I wondered the same thing when I first saw the car. Some stuff is welded in and some is bolt up. We'd have to ask the original builder for his thoughts, but most of it makes sense. The cross bracing is bolt-up so it can be removed to get the engine out. That motor mount was a bolt in but could have been welded in place without causing any trouble. Actually, I'm glad is was bolt in because it made it that much easier to mod it. Some of the damper bracing is bolt in and could have been welded.... Maybe Jamie built it that way because he planned to make some changes.

[gtpilot]

Kaymo - If you look closely, the entire from suspension/motor bay can be unbolted from the cage and firewall...Jim wants to build a new suspension for the front - we will just have to unbolt the whole thing and fab another up when we are done with getting the car on the track again!

Chris - the car can be run with an SIR (24mm vs. unrestricted) and more weight (1855 vs. 2080 - OUCH!) in GTL and I will run it in the two classes. If you look at the new sliding weight scale for GT3 cars the car should be competitive...not saying that I am going to catch up to many years of Nissan development over night but it will be fun.

The really long stroke of the A1 will make it a good SIR motor though! I will have to share some pictures of the head development - that A1 head has cavernous combustion chambers!

-TJ, this coming weekend?

Jim - quit posting on here and get the traingle tower brace done and installed!

Kirk

[jim.mullen]

So after a few weeks of sickness and an ailing back to boot , I got back to work on the racecar. Here's a shot of that painted up front X-brace just sitiing on the slick.


Here's a pic of the rear K-brace being mocked up.


Here it is welded up and media blasted, in raw steel, sitting in place.... Actually, it's a stretch to call that a K shape, it looks a bit like a Delta symbol, so let's call it a Delta Brace.


Here it is painted up. I use the blast cabinet I built as a spray booth also. It works for this because I have a powerful cyclone dust collection system (I built that too) hooked up to the blast cabinet and it pulls a lot of air, moving all the overspray (and media dust, when I'm blasting) to an external vent on the roof.

[strudel]

Jim,

I'm curious to find out how this whole cradle contraption is mounted to the body. It looks like there is a flat sheet of steel? for the firewall and the different sections are bolted to it. Some of it showing in one picture is bolted somehow to the A pillar. There is no brake apparatus as per normal so that all must be internally mounted. Since the oem frame rails are gone the connection to the A pillar makes sense and then is there some strengthening anywhere to the floorpan to hold the bottom of it somehow? That would be similar to the Mini as it mounts to the bulkhead and then under the floor and basically cantilevers off the front of the firewall. Any help with pictures would be super. JS

[jim.mullen]

Jim,

I'm curious to find out how this whole cradle contraption is mounted to the body. It looks like there is a flat sheet of steel? for the firewall and the different sections are bolted to it. Some of it showing in one picture is bolted somehow to the A pillar. There is no brake apparatus as per normal so that all must be internally mounted. Since the oem frame rails are gone the connection to the A pillar makes sense and then is there some strengthening anywhere to the floorpan to hold the bottom of it somehow? That would be similar to the Mini as it mounts to the bulkhead and then under the floor and basically cantilevers off the front of the firewall. Any help with pictures would be super. JS

Hey Jerry,

That piece that looks like a flat sheet of steel is just a thin aluminum firewall that covers a tube frame structure (a bulkhead) behind it. So all the parts that you see bolted up are actually bolted to the bulkhead behind the firewall. If I remember right, the lower frame rails run the length of the chassis, and so it's all the upper stuff that is bolted on. I'll check again today and try to take some more pics of the chassis if I have time. Don't tell Kirk that I'm not welding.

[gtpilot]

Don't tell Kirk that I'm not welding.

I have the reach from Irvine, CA... ...who do you think you are kidding?

Kirk