[Formulajones]

Originally Posted by jhein

So I wore out my MT drag radials. I have the BFG 255/60 15s back on it now. I prefer the ride and handling/cornering of the BFGs but the traction under acceleration sucks. Are there any better 15" street tires? If not, are there better offerings in a 17" tire? I don't really like the look of 17"wheels as much but if the tires in that size are much better I may do it.

I'll be straight here, you really aren't going to do any better than a MT drag radial if you want straight line traction and drivability. I've been running them for 25+ years on one of my street cars full time. There is no difference in normal drivability or cornering over any hard 15" street tire. You can't tell they are on there. Hell I drive that car 200 miles back and forth to the drag strip and several thousand miles a year every where else. 15" tires on all my cars and we live in the mountains, works fine. Many of the cars have a bunch of suspension tricks to help them 60 foot well, doesn't hurt any of the drivability. I'd bet anyone could get in any one of them and drive it up the mountain roads and not even tell a difference from a bone stock muscle car. They still turn as good as they did when new and that's good enough for me.

You'll have to decide what's good enough for you and what direction you really want to go with the car. If you want a real canyon carver then there are a bunch of suggestions already in this thread with bigger wheels and suspension mods suited for that type of thing if you want to go down that rabbit hole. Just don't expect it to 60 foot well.

Personally I think the answer to your original question was a simple one. Put another set of drag radials on the car and forget about it. When you reach a certain HP level that's just muscle car life if you want straight line performance.
I find it pretty funny at cruises seeing big HP cars, some with turbos, and they just have BFG radials on the back. All that power and it won't go anywhere. My sons VW bug would eat that for lunch at any stop light.

[jhein]

Originally Posted by Formulajones

I'll be straight here, you really aren't going to do any better than a MT drag radial if you want straight line traction and drivability. I've been running them for 25+ years on one of my street cars full time. There is no difference in normal drivability or cornering over any hard 15" street tire. You can't tell they are on there. Hell I drive that car 200 miles back and forth to the drag strip and several thousand miles a year every where else. 15" tires on all my cars and we live in the mountains, works fine. Many of the cars have a bunch of suspension tricks to help them 60 foot well, doesn't hurt any of the drivability. I'd bet anyone could get in any one of them and drive it up the mountain roads and not even tell a difference from a bone stock muscle car. They still turn as good as they did when new and that's good enough for me.

You'll have to decide what's good enough for you and what direction you really want to go with the car. If you want a real canyon carver then there are a bunch of suggestions already in this thread with bigger wheels and suspension mods suited for that type of thing if you want to go down that rabbit hole. Just don't expect it to 60 foot well.

Personally I think the answer to your original question was a simple one. Put another set of drag radials on the car and forget about it. When you reach a certain HP level that's just muscle car life if you want straight line performance.
I find it pretty funny at cruises seeing big HP cars, some with turbos, and they just have BFG radials on the back. All that power and it won't go anywhere. My sons VW bug would eat that for lunch at any stop light.

Thanks for the input. I appreciate your experience but I could clearly feel the difference between to BFGs and MT DRs in cornering. If not for that I would have stuck with them. Who knows, maybe this will just be a waste of money. But it's a hobby, it's supposed to cost money.

[twilightTA]

FWIW this is how the 77 sits with the PTFB GT springs and all of the other PTFB parts. Tires again are Continental ExtremeContact Sports 255/45/17 and 285/40/17. Using the highest PTFB shackle setting (which technically is the lowest bolt hole).

[Formulajones]

If you run proper air pressures for street driving there is literally no difference in cornering abilities or feel between a bfg ta and a mt drag radial.
The mt drag radials have a fairly stiff sidewall for a drag tire. When aired up to 32-34 lbs they act like a regular tire with the only real difference being a sticky rubber compound.

If you're feeling a difference something is wrong or off base some where else

In fact if you really push the car I'd guarantee you'll find oversteer with the bfg ta before you would with the drag radials on the back

[jhein]

Originally Posted by Formulajones

If you run proper air pressures for street driving there is literally no difference in cornering abilities or feel between a bfg ta and a mt drag radial.
The mt drag radials have a fairly stiff sidewall for a drag tire. When aired up to 32-34 lbs they act like a regular tire with the only real difference being a sticky rubber compound.

If you're feeling a difference something is wrong or off base some where else

In fact if you really push the car I'd guarantee you'll find oversteer with the bfg ta before you would with the drag radials on the back

Maybe it's the tire size and rim width combo? I have 7" wide rims. For the MT DR 255/60/15 they recommend a minimum 7.5" width. For the BFG 255/60/15 it's 7.0 minimum I don't know what that sidewall distortion does but the MT DRs feel pretty sloshy in cornering to me. It doesn't feel like breaking away, feels like a softer tire. Anyway, if I could have the road feel of the BFGs with the traction of the MT DRs that would be great.

As for tire pressure, that's also interesting. When I got the MT DRs I initially had them at 32 psi. At that psi my treadwear pattern was basically the center of the tire. I eventually worked my way down to 24 psi. There, the treadwear seemed more even. But after 2500 miles at 24 psi, they wore out in the center. They say it's not a growing tire but I'm not sure.

Edit: I run my BFGs at 24psi.

[Formulajones]

Sounds like a rim issue. Likely not wide enough. I run mine at 32-ish on the street with an 8.5" rim. I get good wear. In fact I run them for a couple years with some drag strip runs mixed in before they need changed. Probably 10,000 miles or a little more.

You'll figure something out you'll be happy with, just takes time and some experimentation.

[Gator67]

Originally Posted by Formulajones

You'll figure something out you'll be happy with, just takes time and some experimentation.

Even though we went with full front and rear suspension systems in our last two cars, there's still a lot of experimenting required to get things where we like them. Finding the best balance of compromises is quite the rabbit hole, and it goes beyond just making adjustments in the components and seeing what happens. My DSE car in the photo was fairly well sorted from the start, but I still ended up switching out the rear shocks and springs twice. My son's Ridetech car has less than 200 miles on it, and we've already replaced both the front and rear shocks and springs, front tires, and we're likely going to replace the front springs again, and probably upper ball joints as well.

[JLMounce]

Originally Posted by jhein

Maybe it's the tire size and rim width combo? I have 7" wide rims. For the MT DR 255/60/15 they recommend a minimum 7.5" width. For the BFG 255/60/15 it's 7.0 minimum I don't know what that sidewall distortion does but the MT DRs feel pretty sloshy in cornering to me. It doesn't feel like breaking away, feels like a softer tire. Anyway, if I could have the road feel of the BFGs with the traction of the MT DRs that would be great.

As for tire pressure, that's also interesting. When I got the MT DRs I initially had them at 32 psi. At that psi my treadwear pattern was basically the center of the tire. I eventually worked my way down to 24 psi. There, the treadwear seemed more even. But after 2500 miles at 24 psi, they wore out in the center. They say it's not a growing tire but I'm not sure.

Edit: I run my BFGs at 24psi.

In general, when you put a wider tire on a wheel it’s not suited for, the increased tire bulge has a softening effect on the sidewall. If you’re viewing the tire as a spring, what you’ve effectively done is to tilt the spring at an angle. You lose effective rate and thus the tire acts as a softer spring.

Stretching the tire into a wheel has similar effects in the opposite direction.

So yes if the MT was placed on too narrow of a wheel compared to the BFG, you may feel that as some lethargic handling comparatively.

However if you chose an MT tire that was better suited to your wheel with you probably gain that back.

[jhein]

Yeah, I knew that tire and wheel combo wasn't ideal but at the time you couldn't get an 8" Rally II. They're still a little hard to find, I think. And I wouldn't want anything smaller than a 255 tire with wider being even better. Anyway, I never really looked into the larger size wheels because I was never that fond of the look. But now that I've discovered the 255/50/17 and 275/50/17 sizes that's changed things. I've got the Year One 17" Rally IIs one the way so I should be able to get them on the car soon. So, while not a drag tire, it is wider and taller so that may help a little. That plus the eventual suspension and chassis mods will hopefully be some improvement. I think it will definitely handle better but traction may still be a problem. If that's the case, then I'll try the M&H drag tire in 275/50/17.

[jhein]

Well, I talked with Dave at PTFB and I may be going down a rabbit hole. I was going to just do the rear suspension with sub frame connectors and solid sub frame bushings. Now I'm thinking about doing the whole front suspension too, possibly including G-bars. All because I asked about tires. LOL. And not only that, but with 17" wheels, I can get bigger front brakes too.

I guess I've already crossed the line into a restomod, I'm not sure of the exact definition of a pro touring car is but I might be getting there.

[b-man]

Originally Posted by jhein

Well, I talked with Dave at PTFB and I may be going down a rabbit hole. I was going to just do the rear suspension with sub frame connectors and solid sub frame bushings. Now I'm thinking about doing the whole front suspension too, possibly including G-bars. All because I asked about tires. LOL. And not only that, but with 17" wheels, I can get bigger front brakes too.

I guess I've already crossed the line into a restomod, I'm not sure of the exact definition of a pro touring car is but I might be getting there.

https://forums.maxperformanceinc.com...d.php?t=610357

It’s easy to do….mission creep.

[JLMounce]

Originally Posted by jhein

Well, I talked with Dave at PTFB and I may be going down a rabbit hole. I was going to just do the rear suspension with sub frame connectors and solid sub frame bushings. Now I'm thinking about doing the whole front suspension too, possibly including G-bars. All because I asked about tires. LOL. And not only that, but with 17" wheels, I can get bigger front brakes too.

I guess I've already crossed the line into a restomod, I'm not sure of the exact definition of a pro touring car is but I might be getting there.

Mission creep for sure!

I just ordered a bunch of stuff myself. Decided to have Global West build me a set of their Cat5 leaf springs. The car is going to actually come up in the rear a little bit, so I added some QA1 double adjustable hybrid coil overs for the front and matching double adjustable shocks for the rear.

And yes, before somebody calls me on it, I still have misgivings on the hybrid coil-over design, specifically its propensity to side load the shock. However, as I researched for a couple weeks options that don't require fabrication, it was pretty easy to see why the design exists.

Without trial and error fitment, it's impossible to know if you'll be able to get a stud mount coilover like the RideTech HQ or the Verishock conversion to fit without having to cut out at least part of the upper spring perch. That the point you have to do that, there's no reason to use the stud mount and you should go to a Chicane mount of Global West's coilover mount to gain more shock length and get a double shear eye mount.

The QA1's were about the only reversible way I could get to a 600 lb spring that the car desperately needs. I still believe the Verishock design is superior, but going to a double adjustable from a non-adjustable will allow me to tune the balance I need a bit better.

I'm hoping with a bit more ride height and shock length, I'll have a slightly better ride as well. Through this process I did discover that the Hotchkis leaf springs I have on the car now were too short and have the shackles pointing towards the front of the car, reducing my available articulation. This is also likely one of the reasons the car has a good bit of impact harshness.

[jhein]

Mission creep for sure but as b-man points out in the thread he linked, it's necessary. You put in a much more powerful motor then you need a chassis, suspension and tires to put it to the road and keep it under control. In a way I feel bad about loosing the originality but honestly, I bought the car to drive it. So it definitely needs to be powerful and fun but also safe so I don't end up like the guy in the GTO crash thread currently in the Lounge....

BTW, what do you guys think about the G-bars?

[b-man]

Just stash all the original suspension pieces under your workbench or some appropriate place and keep them for the future if the car should ever change hands.

It’s all bolt-on stuff so it’s not like you’re butchering a classic Trans Am.

Having the car stop and handle better can’t be a bad thing, if you’re keeping it between the lines the body will stay straight…..plus you’ll enjoy it more and drive it more often.

[jhein]

Originally Posted by b-man

Just stash all the original suspension pieces under your workbench or some appropriate place and keep them for the future if the car should ever change hands.

It’s all bolt-on stuff so it’s not like you’re butchering a classic Trans Am.

Yeah, so far I haven't done anything that's irreversible. But, I was planning on welding the subframe connectors. I don't know how easily that could be reversed. But honestly, I think anyone who would want a bone stock car wouldn't want the hassle of undoing all this stuff. But you never know.

[Gator67]

Originally Posted by jhein

I guess I've already crossed the line into a restomod, I'm not sure of the exact definition of a pro touring car is but I might be getting there.

Since you're headed in the pro-touring direction, you should consider spending some time on the pro-touring forum if you haven't done so already...there are some great examples of builds at different levels of complexity/expense. It's not as active as it used to be, however, you can learn a lot from others' projects. A bunch of guys here in town have gone the pro-touring route with their second gen TAs, and it seems most have ended up with Ridetech because their stuff is largely sorted out, bolt on, and less expensive than other big players like Detroit Speed and Speedtech. Their cars get driven a lot too, including the Bandit Run every year, and as far as I know, none have considered switching back to factory stuff. Things do tend to snowball though. For example, almost everyone eventually ends with 18" wheels to accommodate bigger brakes.

[HWYSTR455]

Herb Adams in his 'handbook' catalog outlines the anti-squat mod so you don't have to do the math. I did that mod in the 80s.

It's nice that GW and others make the bracket, but not sure if it's the same as what Adams pointed out. I suspect it is, since there's not much room to work with there. And Doug knows what he's talking about.

As for leaf springs, GW has the reverse wrap springs that are the way to go. I used to run Rancho springs that had the 2nd leaf that partially wrapped the front eye bracket, which acts like a traction bar, so there would be no need for additional traction devices.

Here's 2 clips where Doug talks about using the spherical bearings in the Cat 5 reverse eye leafs:

https://www.youtube.com/watch?v=PJzz9U37gwo

https://www.youtube.com/watch?v=iDin7omk75w

Although it's stated it particularly advantageous in a road racing app, it's also very effective in a drag app.

Just to say, once the suspension is full-articulating, you can tune with shock settings, be it drag or road racing, and you can go back and forth by adjusting the shocks. (and potentially loosening/removing end links on front sway bar).

Wheels. Well, first, a 255 is about max for an 8" wide wheel, and if you have 7s, you just plain need to switch it up. IF, you are switching it up, 18s make the most sense when choosing between 17s & 18s, the tire selection is much better. Not to mention it opens up the door for bigger brakes.

One other thing you have to keep in mind with leaf springs cars too is the fact that tires 'squirm'. The more sidewall, the more they squirm. And the sidewall starts getting pretty close to the leaf when you start going wider wheels and tires already. The only way to really go is inward. You can roll the lip, but you will still be limited to about a 295-305 size max. (Unless you move the springs in or go to the DSE link setup, which also requires notching the frame rails. Yes, you can jack it up to the moon and fit stuff under there, but that destroys the handling).

Long story short, you can't have the best of both worlds. You can get somewhere in the middle and be happy though. If you do more 'road' driving, you can lean more that way, and visa-versa.



.

[HWYSTR455]

Originally Posted by jhein

Yeah, so far I haven't done anything that's irreversible. But, I was planning on welding the subframe connectors. I don't know how easily that could be reversed. But honestly, I think anyone who would want a bone stock car wouldn't want the hassle of undoing all this stuff. But you never know.

If you are thinking about subframe connectors, the GW type are the best option:

https://www.youtube.com/watch?v=ltjtqeh7_AA


.

[HWYSTR455]

Reverse eye leaf benefits:

https://www.youtube.com/watch?v=rxhM3S5J3gA

.

[twilightTA]

Agreed on the thoughts on 18s. Still not sure I love the 18s look but my 17s sure are tough to find good tires for. The Continental ExtremeContact Sports I believe are the best all around option for them but only had Nittos before to compare against.

Seems like everyone can get a bit biased towards the brands here. Good news is you don’t hear too much negative about any of them. The only issue I’ve had with one of them is having to return Ridetech lower control arms twice due to welding defects on them. Gave up and went back to order PTFB lowers instead..

My bias has been towards PTFB as everything has fit perfectly and substantially improved my car. The pricing usually is much cheaper. I have no complaints outside of the shipping times can take a long time and you have to be patient as Dave’s a one man show and not a big company like some of the others.

I’m still debating that cat 5 global west system on my PTFB springs or doing the sphero bushing setup instead. I like how the Global West bushings have grease fittings on all of them.