Friday, February 27, 2015

The Front Crossmember.

Being that this is the land of litigation, I should probably have a disclaimer of some kind. Here ya go:
Don't try any of this at home. These are not instructions. There's an enormous amount of thought and care behind this that isn't mentioned in the text, and my flippant tone should not be construed as a haphazard approach. If you try any of these things yourself, you alone are accountable for the results.
Crap. That means I'm accountable for this. Oopsie. 
The original plan had been to fit a rear axle out of an 1800E or ES. One benefit that this would offer is that - though the bolt pattern for the wheels wouldn't match - the track width would remain at 51 inches. Had we found such an axle, we could have switched out the front rotors for a pair with the later bolt pattern and left the original front crossmember and suspension and steering stuff in place. But the 142 has a track width of 53 inches, so the track width (and thus the wheel offset as mentioned previously) wouldn't match.
The way to make the front track width match the rear was to put the complete crossmember and suspension and steering stuff from the 142 into the 444. Simple, right?
Well used front end, post removal:

... and a similarly nasty 140 piece, pre-installation:

This was the Really Intimidating Thing. Though the crossmember is overall wider than the one that came out, the shock towers are closer together... just enough that the piece doesn't fit without cutting away some of the material that, to be blunt, supports the weight of the forward half of the car. Not only that, but the upper A-arm pivot bolts want to share some of the same space as the "horns," or "longerons," which protrude forward from the firewall; which means that after cutting away some of the flange on the bottom, you also have to cut out some of the structural material that your life will depend on when you're driving a hundred miles an hour over speed bumps in Mexico. (Don't worry - the roll cage design includes reinforcement for this area.)
Viewing from the right front, looking toward the middle of the car. On the bottom, you can see that there's about a half inch of the flange cut away (this accommodates the shock tower) and the large sort of rectangular hole in the box section allows the upper A-arm to clear:
[Note: swapping crossmembers with the engine still attached to the transmission and hanging from a hoist is not recommended. Do as I say, not as I do.]
I'd searched online to see how others had dealt with this and found that some people had squeezed the box sections to make them narrow enough to accommodate the crossmember (this didn't seem ideal to me, and I don't have anything that can squeeze something of this scale) and that most of the other cars I could find had what I now have: cuts.
Christopher Georger (you might know him from the Brickboard or other online forums) has done this very swap to two PVs (and has done a much prettier job of it than I) so I contacted him with a long list of questions. There's nothing like primary source reference material. I'd like to take credit for being smart and innovative, but the fact is that he gave me answers and insights I'd never have come up with on my own.
The one thing he did that I didn't mimic (aside from nice clean cutting and welding) is that he notched the frame so that the crossmember would tuck higher up into the car. If you just bolt it in, like I did, the ride height with the stock springs will be absurdly high. Christopher notched his car so he'd have a sensible (and close to stock) ride height, then he welded in a bunch of reinforcement so that the car would remain safe and roadworthy.
For this car, we want a ride height that's close to stock, which is on the tall side for a race car. But we're also running some pretty firm springs, and the goal is to have close to 6 inches of suspension travel at the wheel (more would be ok, less would not). After lots of screwing around and measuring, it was determined that we could run much shorter springs and maintain the travel we want; and that this could all happen without notching. So no notch.
Being paranoid, I welded a bunch of reinforcement into the inside of frame members before then welding them closed. Can't be too careful. Hope they don't break.
Crossmember dry fit. Note that the idler arm isn't yet bolted to the frame. Also, everything is really dirty and not really worthy for your inspection:

Once the member was in place, it was easy to notice that the engine mount brackets aren't where they need to be. Cut drill weld presto. And geometry being what it is, the engine now sits about an inch and a half lower than it did with the original crossmember. Rather than elevate the engine mount brackets, I adapted other things to fit this lower installation, as it will help maintain a low center of gravity (that's a good thing) and the oil pan is still well above the low point on the crossmember, so we should be alright with getting over speed bumps and such.
Stock springs, I'm told, are right around 270lbs per inch. That means it takes 270lbs to compress one of the spring by one inch... but you have to be math smart to take into account the length of the lower A-arm and the fulcrum point and other magic leverage stuff in order to know what that really means in terms of ride quality and handling once the spring is in the car; and what the resulting effective wheel rate will be. I talked to lots of people who know more about this than I do, and finally settled on 450lb springs. They are very different than the originals. Not only are they a LOT firmer than the originals, they're a lot shorter. 8 inches versus 11.5.
Old versus new:

The front suspension bushings, tie rods, center rod ends and balljoints were all replaced with new pieces from ipd. Most of those parts are stock issue, though the bushings are urethane. I'm sorry I didn't get photos of the shock arrangement. Stock 140 spec shocks, of course, don't fit because the suspension is much lower than original. After more measuring and puttering, the solution was found: PV spec front shocks can be adapted fairly easily - using the lower mount bracket from the original 142 shock allows the PV shock to interface with the lower A-arm. For the top, a "pin to eye shock adapter" makes the perfect connection between the 'pin' side (142 crossmember) and the 'eye shock' side (PV shock). The rear Bilsteins had come from VP Autoparts; the fronts were sourced through ipd.
The PV front swaybar, of course, doesn't fit anymore. Now the car has an ipd 140 series front bar. The saddle brackets for the 140 bar are too tall - they interfere with the steering arms - so we're still using the shorter saddle brackets and bushings from the PV kit.
Another thing I don't have pictures of is the steering box and idler arm fitment - I'll get some of these when we get to the 'Steering' blog post. This was another source of way too much thought and worry. Moving the box and idler fore or aft affect the steering response (somewhat) and has a direct influence on what's called the Ackerman angle. Without going into a lot of explanation, the Ackerman has to do with the fact that your outboard wheel has to turn a different amount than your inboard wheel in order that they track essentially parallel as you go around a corner. The outboard wheel travels a larger arc, and it's not a constant difference, and it has to be replicated from one side to the other. Fancy. Moving the stuff that influences steering around affects how all that works.
Anyway, the box and idler are as close to the same distance forward of the wheel centerline as physically possible given the other limitations of the installation as a whole, and after math that's way outside my comfort zone it was determined that the Ackerman would be only slightly affected (and that the effect on steering input and response would be mitigated somewhat by camber... sort of). Of course, when you change one thing, everything else is affected... so after it was all in the car and together, it became apparent that the drag link was a little bit short. Cut it in half, welded the two halves onto a rod that fit inside and then also to another tube in between. I did my level best to bend the thing after it was all welded up but it's way stronger than I am.
The final step related to the crossmember was to fit the brakelines. We're going to run a front/rear split, which means that we have to disable the 'dual circuit' feature of the front calipers. After finding a couple of pretty good writeups online from the BMW and the Datsun guys, I basically mimicked what they'd done: Use a T fitting to split the single flexible line such that it feeds both circuits in the dual circuit calipers. The BMW guys are doing this with dedicated track cars, so I'm thinking we'll be ok. If you want to read up on their approach, it's here:
The Datsun guys' version is here:
Initial dry fit. Note: this is not the T that we stuck with, nor the lines. One of these lines has 7/16" fittings and these absolutely must be replaced with 3/8" fittings so they'll match the rest of the car. Illustration purposes only.

The original flex lines approach the caliper from the front. These approach from the rear, and I didn't want any of the brake plumbing any lower than absolutely necessary. A few minutes with a hacksaw and a drill (and my favorite raw material, 90 degree angle aluminum) and we have brackets to secure the flex line at the chassis end.
Rough start:

Less rough. Not pretty, but nobody's going to see it (present company excepted). This is the one for the right hand side:

Installed. Viewing the left; bracket is secured to the upper shock mount. Suspension travel doesn't stress either end of the flexible brakeline, which is probably a good thing.

And that's about it for the crossmember. This got a whole lot of thought and a whole lot of questions came up along the way. I'm enormously grateful to Christopher for sharing his insight and understanding in this arena.

Thanks to Christopher Georger. ; and the sites mentioned above.

Suppliers for items listed in this post: VP Autoparts, Oil Filter Service, Portland OR (hydraulic parts), Chris Horn Apocalypse Cider and Volvo Parts [], ipd, True Value Hardware.

'til next time, then. Cheers -

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