V8 front suspension

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Re: V8 front suspension

Post by jhayden » Mon Jun 17, 2019 12:34 pm

Speedbug,

Currently your swap exceeds Alvin’s U20 weigh-in by 130 pounds. If Alvin’s car was de-smogged at the time (?), the difference between your 302 swap and a stock U20 (all U.S. U20s from Oct '67 were SRL311U models) curb weight would be even less.

Regarding the “front heavy” weight distribution concern being expressed by a few, some interesting stats emerge from the previous posts:

SRL311U stock without load .............. 58.66% F, 41.34% R

SRL311U stock with load .................. 55.4% F, 44.6% R

Speedbug 302 swap without load ......... 55.56% F, 44.44% R

Really difficult to see a “front heavy” problem with your “iron” swap there based on your current numbers.

Jon

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Re: V8 front suspension

Post by speedbug78 » Mon Jun 17, 2019 12:39 pm

Rear suspension V8 discussion started here: viewtopic.php?f=3&t=31959
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Re: V8 front suspension

Post by Alvin » Mon Jun 17, 2019 1:39 pm

jhayden wrote:
Mon Jun 17, 2019 12:34 pm


Currently your swap exceeds Alvin’s U20 weigh-in by 130 pounds. If Alvin’s car was de-smogged at the time (?), the difference between your 302 swap and a stock U20 (all U.S. U20s from Oct '67 were SRL311U models) curb weight would be even less.
Jon yes the weigh-in with the U20 was de-smogged. Trying to think of anything extra other than the roll-bar.
EDT: found a pic
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Re: V8 front suspension

Post by JT68 » Mon Jun 17, 2019 4:21 pm

As mentioned before, the 302 car still appears to be a "work in progress", so comparing it to cars that are pretty much complete is definitely apples/oranges. Many of the street cars appear to have full interiors, top, trim, everything, and probably other additions too. Big brakes? Either way, the vehicle weights from Nissan are almost certainly correct, so anything heavier than that already has weight additions. The Nissan weight is clearly what the designers worked around.

Unless the 302 car is declared "finished" it is probably getting another 100-200lbs of stuff too. Brakes, rear end,stereo gear, trim, cage? roll bar?, safety equipment, driver.. of course 25lbs isnt significant, 250 is.

Two identical cars, one with a SR, one an iron V8, sorry, the iron V8 and all the stuff that goes with it does weigh significantly more, there's just no doubt. Regardless whether it's a 132.5, 225, 275, 325lb difference, all things being equal, the SR roadster will handle better, the V8 car will be faster in a straight line. If you are into that, it's cool.
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Re: V8 front suspension

Post by JT68 » Mon Jun 17, 2019 4:30 pm

speedbug78 wrote:
Mon Jun 17, 2019 11:34 am
JT - agreed. I was hoping to start another separate topic on the rear suspension after getting the front sorted. Right now I'm mainly concerned with street manners and any racing will likely be 1-2 years away. I saw some references to trying coil overs, and I have used the QA-1 adjustables on other projects. There are many spring rates available for them. Would it make sense to convert in this case, or do you feel that the DP springs you reference will be adequate?
Yes, they are probably just about the right spring rate for a VA car They would also lower things a little which might help too unless you have a deep sump.

Overloaded springs make things pretty crappy in cornering-front, rear, doesn't matter.

If you are ambitious yes, coil overs certainly have more tuneability, but tons of work and you can certainly make things worse regarding handling&ride if not careful.

For the back, a 4-link solid posi rear is probably the most bang/buck. Alvin has posted photos of that before. IRS is even more work since you radically change the frame. Looks like another thread started on that- I'll check it out.
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Re: V8 front suspension

Post by jhayden » Mon Jun 17, 2019 6:04 pm

JT,

In your first post in this now lengthy thread you refer to “the problem is 100’s of pounds of iron in the front end,” and “the balance of the car is gone,” and “the front suspension is highly pre-loaded and the rear way too light.”

Please refer to Speedbug 302’s current (no one questions whether it’s a work in progress, so let’s please dismiss the straw man arguments) weight distribution numbers, and explain (1) how those claims are showing up in the current numbers? (2) How would the addition of all the items you mentioned (interior, top, trim, roll bar, stereo gear, etc.) be expected to exacerbate the problem of “highly pre-loaded” front and rear “way too light.” (And, besides, if he’s planning on fast quarter miles, how much of that stuff will he install?)

If all that’s too challenging, can you answer how much heavier an iron block LT1 engine is compared to an aluminum LS1? (No fair peeking at the reference I provided earlier!).

Jon

It’s always been the case that swapping engines is easier than changing some folks’ mindsets about the change.

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Re: V8 front suspension

Post by speedbug78 » Mon Jun 17, 2019 6:50 pm

Just to be fair my car has most of its interior, trim, roll bar and stereo gear all there when I weighed. I think the stereo head, vertical windshield trim, shift boot, center console padding and horn button are missing. PO added extra speakers and sound deadening under the carpet. Here is a pic.

Edit: I remembered some of the cardboard on the firewall is gone since it kept catching fire when I was welding.
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Re: V8 front suspension

Post by JT68 » Mon Jun 17, 2019 11:03 pm

jhayden wrote:
Mon Jun 17, 2019 6:04 pm

If all that’s too challenging, can you answer how much heavier an iron block LT1 engine is compared to an aluminum LS1? (No fair peeking at the reference I provided earlier!).
I think there's about 100 lbs difference between an SBC AL block and SBC Iron block right? I read somewhere 75lbs LS1 vs LT, but if it was me, I wouldn't even use ANY 90degreeV unless I built a new subframe - the fit is just too poor in the roadster frame. Weight aside, that's probably a big reason it's not a popular swap. Also a good thing AL heads were used on this swap, clearly that helped in the weight department.

To clarify, I don't mind engine swaps in general, but most V8 swaps I've ever seen are "not particularly elegant" to be PC. To be more descriptive, there are lots of very nice SR swaps out there that are probably worth 20k-30k+ or more. I've never seen a v8 swap that I didn't consider a pending parts car. Sorry Jon, I don't think you will convince many that an SBC/SBF is a better all around swap than a SR,KA,CA-T etc. Good luck with that. The more V8 swaps that happen, the more valuable the more original cars become, so we all thank you for that. Conversely, there are lots of beautiful SR swaps done that are worth the big bucks. Michael's swaps are beautiful and there are many others too.

Speedbug, if your car is fully trimmed out, that's all good, certainly no offense intended at all, I'm sure it will make a great strip car! IMHO, the more weight you can move to the rear, the better things will be in the handling department. FWIW.
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Re: V8 front suspension

Post by jhayden » Tue Jun 18, 2019 9:55 am

JT,

Please re-read your first post on this thread. You (not I) suggested Speedbug make an LS swap rather than his 302. Still okay with that recommendation?

Jon

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Re: V8 front suspension

Post by speedbug78 » Tue Jun 18, 2019 10:07 am

Hey guys, lets pull this back on track a bit. Does anyone have the dimensional layout for all the front pivot points on our front suspension? I assume someone has the info for a calculator like: https://www.racingaspirations.com/apps/ ... alculator/

FergO2k - is this info in the spreadsheet you were talking about?
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Re: V8 front suspension

Post by FergO2k » Wed Jun 19, 2019 9:37 am

Nop, mine was weighing comparison only, and only front vs rear for both 302 and stock?U20 car (wasn't done with corner weights, just trucking scale and 1/2 the car on, 1/2 the car off.
I PM'd it t you, let me know if it didn't come thru.
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Re: V8 front suspension

Post by speedbug78 » Fri Jun 21, 2019 11:50 am

On a side note, would you guys prefer me to document what I actually do to my suspension in this thread, or in a build thread?
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Re: V8 front suspension

Post by speedbug78 » Fri Jun 21, 2019 10:57 pm

Tore into the suspension tonight. It wasn't as bad as I thought. I can probably get away with upper a-arm shafts, upper ball joint boots, and lower ball joints.

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Re: V8 front suspension

Post by speedbug78 » Fri Jun 21, 2019 11:00 pm

I had some 2.5" coil over springs laying around. It doesn't look difficult to convert and use them, but not sure how easy it would be to find the rates that would work. These are 550's but searching shows that roadster needs 700+?
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Re: V8 front suspension

Post by speedbug78 » Fri Jun 21, 2019 11:08 pm

Shocks on the car are KYB gas a just (black?). Searching indicates these aren't too good for this car?
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