2G Tubular front k-member build - share ideas!

[snowborder714]

I suspect there will be some differences between this unit and one built for road racing.

I asked this question on Facebook (around the arm mounts) and he said they'd be the same.


What's the "15:1" mean in regards to the rack? How is the turning ratio compared to the stock rack?

 

[99gst_racer]

The tube the lateral arm bracket attaches to is .095" wall and 1.25" OD. Pretty strong for that diameter. And then each one is braced in each direction right behind the bracket itself. I'm very confident the design will be strong enough for any application.

I'm not sure what the OE rack ratio is, but the 15:1 is the quicker ratio of the two available Mustang II ratio options.

I mocked up a block and trans this morning and found a clearance issue with the back of the trans and one bar. So, I removed it. I'll rework it and tack it back in tonight. Working on mounting the steering rack right now. Should be another late night in the shop.

Here's mock up pics from this morning:

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[11Banger]

GST I sent you a message

 

[T2Small]

This looks great! I would be curious to hear the weight numbers and any stiffness measurements you could make when you are done.

 

[99gst_racer]

T2Small, as soon as I get it welded up this week, I'll put it on our UPS scale and get a good weight comparison. I'm guessing it's a good 20-25 lbs lighter. I know the rack is a few lbs lighter as well, as will be the lateral arms.

 

[99gst_racer]

Anybody have any constructive criticism? Anything you would change? Anything you don't like about it? If so, hit me with it.

I know there are a few things I would rather have done a little differently, but clearance issues drastically limited options in most cases. Fitting an A/T trans was more difficult than I thought it would be.

 

[gofer]

It looks great Paul.

Just a few ideas. Weld a cover/cap over the end of the open pipe with the LCA brackets on it, the way it's facing I could see it catching a lot of road debris. Also, for the end user, it would be nice to have a small bracket welded on the passenger and driver side to bolt a clamp to and secure SS fuel line supply and return if the stock lines aren't being used.

 

[99gst_racer]

Thanks, Corey. I do plan on capping the end of that tube. The caps will go on last to help prevent pressure build-up while welding up everything else.

 

[99gst_racer]

Here's a shot from underneath with a block, trans, t-case, and steering rack in place.

You must be logged in to view this image or video.

 

[eclipsh]

For anything other than drag racing I'd absolutely do an x or k-brace on the bottom that bolts in in front of the lateral arms and back at the rear body mounts.

I'd also try to bring a brace from the foward body mount down to the rear. I'm just looking at applied loads and how it will resist. With a k-brace you'll have horizontal compression covered very well as well as horizontal shear. You've also got shear in the plane of the firewall covered pretty well but you don't have much perpendicular to the firewall. The body helps to some degree but it is flimsy. As you know, adding a fender brace helps 2g cars stiffness immensely. I could see a lot of that benefit being gained with this subframe if it is braced properly.

Please forgive me if I don't make much sense. I worked a very long day and don't have the time/energy to draw up a diagram.

 

[gofer]

Quick question and sorry I'm so late to this party Paul. Any reason you chose the manual Mustang II rack? Most AutoX DSMer's want to retain their power steering and it seems this was a good opportunity to have the ability to install the Evo rack and pinion with a 13:1 ratio in a 2g.

Really, I'm just wondering if the Mustang II manual rack is the only rack that will work in this k-member or is it easily changed to use the stock 2g rack or possibly even the Evo VIII rack?

 

[turbosax2]

It makes sense to me to brace along the bottom between the control arms. And tie in the factory north-south car if you can, like the factory stays do. I would much rather have it over-braced and heavier than vice versa. Talking road race version, of course.

How hard is it to install the engine from the top with the rear mount welded in? Or removing the transmission without removing the engine? I could see that being difficult considering I usually unbolt the rear mount from the subframe since the other piece is difficult to remove from the transmission when installed. But maybe that bracket could be removed now with the extra space gained from the tubing.

 

[T2Small]

I don't think any serious autox guys would consider this as it bumps us out of Street Modified, and it would be extremely hard to compete in an even higher class.

However us lapping day, time attack, and road racers might be interested. Ease of servicing the transmission would definitely be of concern to me as we already have it harder than 1Gs. Normally I unbolt the rear mount from the trans/block but leave it attached to the subframe.

 

[renovatdkitchen]

Seeing as I am going to be looking at an empty shell in about a month, I'd love to see the progress on this. Looks great so far. But as Gopher was saying, would this require us to loose our power steering?

 

[99gst_racer]

Quick question and sorry I'm so late to this party Paul. Any reason you chose the manual Mustang II rack? Most AutoX DSMer's want to retain their power steering and it seems this was a good opportunity to have the ability to install the Evo rack and pinion with a 13:1 ratio in a 2g.

Really, I'm just wondering if the Mustang II manual rack is the only rack that will work in this k-member or is it easily changed to use the stock 2g rack or possibly even the Evo VIII rack?

But as Gopher was saying, would this require us to loose our power steering?

I used a Mustang II rack on this one because it's going on John's drag car. He already had power steering eliminated and this rack should feel much better than the depowered 2G rack that he was used prior.

I should be able to use literally any rack, including the factory rack.

 

[renovatdkitchen]

Music to my ears. Are you going to sell your front + rear sub frames as a package offer once its ready?

 

[99gst_racer]

For anything other than drag racing I'd absolutely do an x or k-brace on the bottom that bolts in in front of the lateral arms and back at the rear body mounts.

...but you don't have much perpendicular to the firewall.

I'm interested in your suggestions but I'me having a difficult time understand what your referring to. If you get time to whip up something quick in MS Paint to illustrate what you're referring to, I would greatly appreciate it.

 

[4g63monstr]

Will you be able to still mount a dry sump on the rear of the block with this setup like the Magnus dry sump setup?

 

[99gst_racer]

Music to my ears. Are you going to sell your front + rear sub frames as a package offer once its ready?

I'll probably just continue to tackle orders as they come in. I'm a single man operation so nothing gets done quickly. I'll never be to the point where I have 10 of everything sitting on the shelf ready to ship. 1G crossmembers are the only thing that I build in large batches and have inventory on. As it sits, I've been backed up with a list of work for the past 10 months...

Will you be able to still mount a dry sump on the rear of the block with this setup like the Magnus dry sump setup?

I wouldnt know until/unless I have a pump and bracket to mock up. If I had to guess, I'd say it would likely fit, but I would probably need to make a few small changes.

 

[99gst_racer]

It makes sense to me to brace along the bottom between the control arms.

I'd love to do something like that too, but the location of the tranny and t-case don't seem to allow for it. It's a fit fit as is with the 3/4" raised LCA pick-ups, and the current pick-ups design was the best way I could think of given the close proximity of the transmission. I'll see if I can dig up more pics that show some of these clearances from different angles.

And tie in the factory north-south car if you can, like the factory stays do.

In theory, this design doesn't suffer from the same flexing issues that the factory k-member would regarding using the stays to box off the open end. My version doesn't really have an open end that is succeptible to deflection.

I would much rather have it over-braced and heavier than vice versa. Talking road race version, of course.

Without a doubt, I would add additional bracing on a road race version. Possibly even heavier wall tubing in some areas. But the general design would remain.

How hard is it to install the engine from the top with the rear mount welded in? Or removing the transmission without removing the engine? I could see that being difficult considering I usually unbolt the rear mount from the subframe since the other piece is difficult to remove from the transmission when installed. But maybe that bracket could be removed now with the extra space gained from the tubing.

The rear roll stop is actually much narrower than the bracket, so it's not a tight fit, but still controls roll. I did it this way to account for the slightly differing locations of the m/t vs. a/t rear roll stop. This way I can use the same roll stop and in the same location, and it will make it easy to pull the engine without removing the bracket, and it will also fit with both tranny types. Pulling the tranny by itself should be unchanged as well due to nothing running underneath the tranny. Clearances in general should be close to that of the factory k-member.

 

[99gst_racer]

I appreciate the input from everybody on and off of this site.

I hope to have it welded up by the end of the week. I also plan to build the control arms sometime this coming weekend.

I'm looking forward to seeing a weight difference. I'm also looking forward to starting a purpose built road race version.

 

[turbosax2]

In theory, this design doesn't suffer from the same flexing issues that the factory k-member would regarding using the stays to box off the open end. My version doesn't really have an open end that is succeptible to deflection.

I meant the north-south bar that ties to the lower radiator support. But better yet, don't tie the stock one in; make a new tubular one to replace it.

 

[99gst_racer]

I meant the north-south bar that ties to the lower radiator support. But better yet, don't tie the stock one in; make a new tubular one to replace it.

Yeah, I had planned on a tubular crossmember bar to go with it. I imagine John will build his own because his frontend is already tubed. I'll have to design a bracket and figure out a way to allow it to unbolt from the k-member. Should be fun.

 

[eclipsh]

I'm interested in your suggestions but I'me having a difficult time understand what your referring to. If you get time to whip up something quick in MS Paint to illustrate what you're referring to, I would greatly appreciate it.

You must be logged in to view this image or video.

The plane of the firewall (YZ plane in my coordinates) is very well braced. A lateral load (red arrow) won't distort it much if at all.

You must be logged in to view this image or video.

The XY plane isn't as well braced against distortion. A lateral push can create shear as represented by the red box.

You must be logged in to view this image or video.

One good fix for this is a K brace as shown in green. It isn't easy to fit in but Mitsubishi did it with an aftermarket K brace in Japan that fits in similarly. It also prevents distortion in other directions but the one I'm showing is probably the most likely.

You must be logged in to view this image or video.

The XZ plane can distort vertically as I'm trying to show in this pic. It is a little confusing since the picture isn't straight on but the distortion should be perpendicular to the firewall as in the fender moving up and down. The green brace I drew in would help prevent this distortion much like a fender brace does.

I hope all that makes sense now. None of it may be necessary but I see those as weak points that could be improved upon.

 

[counti41]

I should be able to use just about anything that is long enough. The prototype will either use an OE rack or a Mustang 2 rack. But if we go with the Mustang 2 rack, I'd have to special order it with extended inner tie rods to get the length proper (They are about 6" narrower than our OE rack). I'll leave the rack option up to John on this build, but I'm open to suggestions from you road race guys on steering racks for any subsequent k-member builds.

The Ford pinto design steering rack is popular in the V8 custom sommunity for its size and its different length options, it can also be had with a hydraulic assisted steering option as well. would you also be able develop a tubular front core support with a front subframe connector that works with your new front subframe. it would be cool if you can redisign the whole front suspension with lighter components(chromoloy, etc... to help take some weight off the front end. i have lots of ideas just no time equiptment or resources to get it all done. PM me and maybe we can exchange ideas.