V8 front suspension

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speedbug78
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V8 front suspension

Post by speedbug78 » Thu Jun 13, 2019 11:33 pm

The main reason I joined this forum was to ask this. I have a 302 in my '69 roadster. Here are the main points:
- The stock suspension is in need of upper and lower ball joints, a-arm pivots and tie rods. Basically a full suspension re-build.
- I don't road-race, this is a street/strip car, but mostly street
- Above 45mph or 1/4 throttle and this car is pretty difficult to keep on the road as-is
- It could use better brakes

I'm pretty good at fabrication so I figure I've got 3 main options:
- Rebuild all the stock stuff and upgrade the brakes ( ~$2500? )
- Replace the front end ( Mustang II ~$3000+? )
- Franken-build the stock front end. I've read about people swapping ball joints, building heim joint a-arms etc... This is probably the cheapest, but also the most time consuming to get right.

Searching turned up these threads:
viewtopic.php?f=3&t=26857&hilit=mustang+ii&start=15
viewtopic.php?f=3&t=19206&p=165249&hili ... ii#p165249
viewtopic.php?f=3&t=25553&start=15
http://www.risensonracing.com/forums/vi ... .php?t=252

Helpful, but not specific to my questions. This quote (from the last source) concerns me:
The front suspension has some poor qualities for a race car...Bad bump steer, not enough camber gain, etc. If you're going to go to the trouble of upgrading components, try to eliminate some of the poor kinematics while you're at it.
What suggestions do you guys have?
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Re: V8 front suspension

Post by JT68 » Fri Jun 14, 2019 6:55 am

I think you may have mis-identified the problem. Fundamentally, it isn't the suspension that is the issue.

While I agree generally that the roadster suspension is not completely "ideal" for racing, it can certainly be sorted out well for street- there are plenty of very fast roadsters that handle great-both track and street. Lots of options for brakes too.

The real problem is 100's of pounds of iron in the front end. The balance of the car is gone, the front suspension is highly pre-loaded and the rear way too light. I'd bet it is hard to control as you say.

If you really want to improve the handling, suggest you swap to a lighter engine..U20/stroker/SR/Vq/CA18T/LS or other AluminumV6orV8/13B- almost anything, then all you need is decent roadster suspension setup for the weight and proper spring rate. Perhaps sell the 302 to a Mustang or Cobra enthusiast?
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Re: V8 front suspension

Post by 2mAn » Fri Jun 14, 2019 8:00 am

Come on JT! There’s an easier solution especially since he went through all the work to put the 302 in there.

And that solution is an Aluminum block :)
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Re: V8 front suspension

Post by greydog » Fri Jun 14, 2019 10:23 am

Not much to do about the weight/balance other than start over and I sure as heck wouldn't.
I'd think simply replacing the stock components would be easiest since steering/geometry issues are presorted.
The MustangII gives you a rack and pinon as well as common (cheap) repair/replacment parts so given your willingness to fab, that might be the way to go.
I'd avoid the franken suspension approach because it's easy to go down a rabbit hole, have many false starts and still end up with something only marginally acceptable.

Why do you say the brakes need work? Since there's no power assist, it takes a fair amount of pedal effort to stop quickly but I think my roadsters will stop as quickly as my other cars with power assist brakes. If you're intent on making a change tho, the Volvo caliper/Altima slotted rotor setup seems to work well and fits a 14" wheel. Spriso sells a nice kit that uses 300ZX calipers and a custom hat but needs larger wheels. I've also heard of Toyota calipers being used. You may find that a rebuild of the brakes, new fluid and braided lines are all that's needed.
Good luck with your project, I say your other posts and it looks like a very nice start on a unique car.

Dan
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speedbug78
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Re: V8 front suspension

Post by speedbug78 » Fri Jun 14, 2019 10:41 am

I respectfully disagree that my suspension is not a problem. I have very visible movement (at least 1/16") in all of the suspension joints listed above (other than the tie-rods), many of those are missing their grease boots and have very little grease in them. I received the car this way, but I doubt it would handle well with a U20 in it.

I completely agree that the 302 is heavier than the U20. I plan to have the car weighed soon to see just how much. An aluminum block isn't out of the question, but is a lot of investment for ~50 lbs. weight savings. I hoped to have a discussion on suspension setup in a separate topic.

With stock alignment, stock springs and stock sway bar I'm quite sure the car's balance will be off. With a repaired suspension, altered rate springs and sway bar, adjusted shocks, and improved brakes the car will still not have the feel of a U20 car, but how about a Cobra, a Fox body Mustang? Is it wise to put all of that time, effort and money into the car's stock parts, or start with something closer to the end goal?

You guys know these cars best, and I'm not the first to do this swap. However it isn't all that common and may be a case of trial and error. I accept that.

JT - I truly appreciate your input as someone who obviously values the quality of these cars and has a lot of experience in making them go. Please don't interpret what I've written as any dis-respect. Do you have corner weight numbers for a U20 car that I can compare with when I measure mine?
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Re: V8 front suspension

Post by Gregs672000 » Fri Jun 14, 2019 10:51 am

Hopefully some of the others that have gone this route will eventually see your posts and respond. It may be helpful here for those who know their names to post or PM them to you as they may not be on the list as frequently as others. I recall one V8 conversion called "the unfair advantage." I'm far from knowledgeable about such things, but maybe adding some weight to the rear will help rebalance the car.

Glad you have found the site helpful. We try hard to help out all Roadster owners... it's a family affaire here...
Car looks great BTW.
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speedbug78
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Re: V8 front suspension

Post by speedbug78 » Fri Jun 14, 2019 10:54 am

Dan - you were writing at the same time as myself :)

You are correct, I don't really know that the brakes need work. There are a few things that bother me though:
- The car is darty under braking, but this is almost certainly the suspension and steering slop.
- The pedal effort is heavy. This may be changed in any number of ways (different brake pads, changed pivot point of the master cylinder, boosters, etc..)
- The master cylinder makes a loud "click" sound 1/2 way through the pedal travel.
- The front brakes drag. Not so much that you notice it driving or that it builds heat, but definitely more than a newer disk brake car when turned by hand. I suspect this is due to the long time the car has been stored and rust buildup on the rotors.

I don't think I need a large upgrade, just an improvement.
I'd avoid the franken suspension approach because it's easy to go down a rabbit hole, have many false starts and still end up with something only marginally acceptable
Good advice here. This kind of custom work in general can be that way, but best to limit the pain :wink:
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Re: V8 front suspension

Post by Gregs672000 » Fri Jun 14, 2019 11:08 am

The tick sound is probably the pedal... mine does too.
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Re: V8 front suspension

Post by ACote » Fri Jun 14, 2019 11:09 am

For the Brakes, I'd check for cracking at the firewall. It's a common problem and there's been a brace made up to help it. Also the pedal Pin gets worn out causing pedal slop. I'd personally would freshen up the suspension and see how it feels. After market ball joints are around $500 for a full set, give the tie rods a good look over and grease and see where you're at. You could always do brakes later if the stock ones aren't cutting it for the power you have. New A arm spindles are pricey, but if you find yours are bad maybe someone has a good used set.

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Re: V8 front suspension

Post by greydog » Fri Jun 14, 2019 11:50 am

I was checking around for engine weights and found:
U20 is 353 lb
289/302 is 460 lb
So, 100 lb difference. Cerainly not like putting a 409 in a Henry J (don't ask).
I don't have the weights of the Roadster 5 speed vs the T5 but I'd bet it's not huge. the trans is farther back so less of a factor anyway.
I'd bet that you can do just fine with a front suspension rebuild, maybe comp springs (known for high rates) and maybe a pair of JT's Bilsteins with modified valving as icing on the cake.

As to brakes, you are probably right, the pistons are likely sticking in the calipers and hanging up. It might be worth pulling the calipers to make sure the pads aren't sticking in their holders. Mine did on the '68 and squeaked a bit when backing up. I took care to make sure the pads moved freely when I had them off this winter. All better now.
Rather than spend the money to rebuild the stock calipers on our '69, I changed to calipers from a Volvo 240 along with braided lines (see Volvo conversion in the tech wiki). The only thing i did differently was to cross drill the new calipers so I didn't have to use an adapter block or two lines. We got a great pedal feel, and solid braking. We don't track the cars so fade is not an issue, even with the solid rotors.
I've seen a few who have worked in a brake booster/power brake setup. It's not that unusual for the British roadsters but I'm not convinced the effort/cost is justified.
Dan
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Re: V8 front suspension

Post by JT68 » Fri Jun 14, 2019 11:59 am

Fundamentally, it has Tiger syndrome - its always going to be a straight line car with a 302 in the nose. Even if you tighten up the front end components, it will still be misbalanced compared to a lighter engine-there is just no escaping that fact.

Your spring rates and shock damping is also totally wrong for additional weight up front- way off.

So far the other advice is pretty good- would not suggest wrecking the front suspension irreparably by attempting to build it into an american style hot rod suspension with mustangII components-that's a route full of peril.

Brakes are relatively easy to improve upon, but the stock brakes are not really up to the task with the extra weight and power.
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Re: V8 front suspension

Post by spl310 » Fri Jun 14, 2019 12:08 pm

A small block Ford is not a very heavy engine. I'd be surprised if you have more than a 75 pound weight gain. Rebuild the suspension and try it.
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Re: V8 front suspension

Post by speedbug78 » Fri Jun 14, 2019 12:09 pm

Thanks for the weight numbers. Was the 460 lbs with aluminum heads and intake like I am running (curious, but the scale will tell the true tale)?

Sounds like a pretty good consensus to rebuild the stock stuff. I'm glad to hear it as it will be much less time consuming than fabbing new.
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Re: V8 front suspension

Post by spl310 » Fri Jun 14, 2019 12:16 pm

Your 302 is lighter. The 460 weight is a stock engine with iron heads and iron manifolds. You appear to have aluminum heads, intake and tube headers. You will have dropped 75 or so pounds total or more. Do you have an aluminum water pump?
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Re: V8 front suspension

Post by speedbug78 » Fri Jun 14, 2019 12:18 pm

Yes aluminum water pump, aluminum radiator. Steel rods though :wink:

Aftermarket aluminum accessory brackets, no A/C, no power steering, just water pump and alternator. It really depends on what the 460lb weight was measuring.
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