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Reinforcing the front subframe

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I fit my VQ37 in this weekend, had to do some excessive cutting into my front subframe to allow the bottom of the engine/oil pan to squeeze in, without compromising the positioning of the rack and pinion. 

i’ve been thinking of just welding a 16g plate going across the bottom of the sub and welding it... suggestions072800E5-D1D6-4DD3-B340-DAC762A8F249.jpeg.c9cb6fc4c6f84d72b84370a52d474225.jpeg

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Think of what the forces are that your subframe is currently going to be experiencing.

 

It isn't holding the engine up, so all it's doing now is dealing with the lateral forces of your rack and pinion, and bit of vertical force from the front suspension arm rotating in it on each side.

 

Personally I think you'd be better off triangulating the front side to reduce the moment arm your steering rack is going to be putting on it.

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2 hours ago, Neverdone said:

Personally I think you'd be better off triangulating the front side to reduce the moment arm your steering rack is going to be putting on it.

 

 

You definitely need to do this or you may have issues by bending on your rack and it might feel weirdly stickly.  If you corner hard you put a lot of load in via the lower control arm.  

 

Cary

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You've decimated the main lateral load path which transfers tire forces into the body via the lower control arms. The chassis has lost a lot of lateral stiffness. I agree with Cary regarding putting high bending loads into your rack bar and killing steering feel. At best, your lateral dynamics and steering take a hit. At worst, you'll have premature rack failure and fatigue failure somewhere in the crossmember. A shear plate welded to the bottom will certainly help.

 

The engine also looks very close to the crossmember. Are you solid-mounting the engine? In that case, it may very well become a stressed-member in cornering as well...

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A plate on the underside to support the sub has been my initial idea since I learned I had to cut. Im supporting the engine with McKinney motor/trans mounts I purchased. 

Now im thinking I should add a rectangle tubing instead of a plate... ive never had to cut into a sub so im not sure what im getting my self into 😅

 

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This is pretty unbelievably terrible. Sorry to be blunt, but if you don't fix that you're going to end up losing steering while driving and hurt yourself or someone else. Not good.

I would take the xmember, hack the ends off, move them forward so that engine clearance is no longer an issue, weld some nuts inside the frame rail to bolt it up, and fab up a new xmember, possibly using the steering rack mounts from this one.

Or look at buying an aftermarket one from Apex Engineering or building something similar. A round tube won't take up as much space as the stock one, and you could move it forward an inch or whatever you need for clearance and it will affect the Ackerman but it will be a hell of a lot safer than what you've got there. Leon hinted that you had better have that engine hard mounted to have it that close to the xmember but didn't spell it out specifically. Over the years seen quite a few radiators damaged when the engine moved forward under braking and the fan hit it. The drivetrain moves around quite a bit. If it's not solid mounted you need to have a bit of space. I think it depends on the mounts, but on a Z I wouldn't go less than 3/4". That's gut feel though...

https://www.apexengineered.com/store/p7/Front_Tubular_Crossmember.html

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This is what Austin Hoke did when VQ35 swapping his S30

 

http://hokeperformance.squarespace.com/vq240z-build-blog/suspension-cross-member-modification

 

I still think it would be safer to triangulate the front, but he basically just closed it all up.

 

He also seems to have more room in between the cross member and engine. So there's that too.

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Glad to see somebody else also doing a VQ37VHR swap around the same time I am, but you seem pretty far ahead of me since I’m just starting the rust repair/body repair part of mine.

if you haven’t checked out Austin Hoke’s webpage with his VQ35 swap I would highly recommend it, he covers cutting the front crossmember in a whole post with photos that is very useful. And ask Doug at ZFever for his whole PDF of the swap procedures.
check again on where you placed the McKinney Motorsports mount kit? Because to me it looks like you cut out a bit more of the crossmember than you needed If it was positioned better, so you may try to slide your mounts just a little bit closer to the firewall.

I was considering the Apex Engineered crossmember because I thought it might clear, and from speaking to them their piece sits approx 1/2in lower the stock x-member and is made from 1 5/8in diameter tube. My measurements led me to believe that it might work (might need to be notched Still) but since I lost my job at the moment due to the recent crisis I’m not going to take the financial risk Of finding out it doesn’t. Maybe one day if VQ swap become more common they will adjust theirs to work, and it’s not a very difficult piece to replace since our engine won’t mount to it any more.

Definitely reinforce that sucker by boxing up all the areas you cut though and start looking into getting another cross member incase yours starts to show signs of failure while your still Safely testing if she’s roadworthy after you do the swap.

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Or if you feel like taking a crack at being the first to use the Apex Engineered crossmember in a VQ swapped Z that would be a great thing to test to, if you talk to the guy he may work something out with you, I was told they would lower the price and send me an un-powdercoated one for ~$50 off if I wanted to give it a shot.

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Posted (edited)

So if this is a hr or vhr can the engine be placed high enough if a ross performance dry sump is used?

 

The dry sump bolts to the block so the upper and lower oil pans are not used. 

 

In Australia we cant cut modify etc the cross member in a swap so i was wondering if the dry sump system could clear. Need someone who has an engine in the car that can work that out. 

 

BrettR.

 

Edited by BrettR

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Just a quick question, Dan: I looked at doing my xmember kind of like yours and ignoring the stock bushing locations, and it seems to me (vague memory) that literally pulling the steel tube out of the aluminum pinion housing was a potential problem. Did you look into how those are attached, and are you sure that mounting the steel tube is strong enough? Would hate to see your rack disassemble itself on the track. Cool to see slotted LCA holes on someone else's car.

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I haven't had issues with it, but I do want to add a locking mechanism to support lateral loads trying to separate the rack tube from the rack pinion housing.  Right now the engine is out of the car, so it might be a good time to revisit.  An even better solution would be a nice Woodward rack.  Do you have one I can borrow😀?

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@BrettR Changing to a dry sump oil pan for the VQ37 is possible and could make it so you don’t have to cut the crossmember. But the cheapest I’ve seen for a complete setup will set you back $5,500 USD. You can really set the engine where ever you want to make it clear the crossmember, provided you don’t mind reshaping/deleting the hood.

 

@74_5.0L_Z I’m having some trouble accessing getting a good look at your custom crossmember or viewing that PDF, any chance you could re-upload the PDF or post a few more pictures while your engine is out?

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