Comin' in hot!

[Taylor]

So me and my Dad were out for a ride last Friday visiting with Steve Walker, aka nlvtinman.  On the way home  there is a long sweeping left turn fallowed by a stop light.  The speed limit is 40mph and we were around there, not speeding.  As we approached the intersection the light switched to yellow.  We had a decent amount of space to make up but I stayed the course.  A car coming in the opposite direction made a left in front of us so I was hard on the brakes.  The front tires immediately locked up causing us to carry on straight instead of fallowing the slight left in the road.  I let off the breaks, downshifted into second and back on the brakes.   This time they locked again and I was forced to make a quick right turn at the light to avoid rolling into the intersection.  

What's up with that??  135r tires must be too small, I guess, and need another look.  I had been wondering if the drums with metal woven shoes were enough but I guess if you can lock them up on dry roads than the brakes aren't the parts that need attention.
Anybody have advice for a possible upgrade or were the stars just aligned?  I have never had that happen before anyway.

Taylor

[andy198712]

its down to grip, you have the best brakes in the world but if the tyres cant grip..... 135 is skinny too.... stickier rubber and or wider fronts would help

[TexasTom]

What air pressure do you run in your 135s, Taylor?
It's all about contact patch ... 22 or so psi would be max for the fronts.
Still, 135s are mighty slim.

TxT

[wolfswest]

Taylor,
Had the same problems before with 135’s.  I hated them and upgrading to a 145 looked ridiculous to me, it’s just a cm wider…    So I recently upgraded to 175/65/15 tires.  These tires are the exactly same height as a 145, so it looks good from the side!  No skinny too low smart tire look.  I ‘ve chosen for a Pirelli cinturato to stay in the theme, all though it’s a newer looking tire it isn’t too modern.  It’s a frequent size because the new mini coopers run them.  So I guess you can find them also pretty easy in the states.
I’ll never go back!   

[nlvtinman]

Taylor,
How was that for a wild ride...Glad to read that  you are not talking about needing some bodywork to be done on your Dad's car.
Did you both head for the TP when you got home, there had to be some in your pants.

Steve

[Jason Foster]

HMMMMM    I'm about to put new fronts on my car, found firestone F560 145's for 73 bucks thanks to a tip from Pep but after seeing Daryl's wide fronts the other day and now reading this along with Texas Tom's recent postings of wide fronts and my struggles driving around on my M&H's lately the thought of a wide patch is appealing. Heck maybe this falls into Jim's post of things to come....is the day of the 145 being the go to coming to an end? Big decision to make don't know if I can make the change from tradition but it seems a logical choice.

As for you question Taylor I'd say 135's are the main issue. I too run drums all the way around and although I do feel it's a risk they are for the most part adequate. There have been a few instances where fade has come into play but for the most part they keep up with what I need.  

[Rennsurfer]

Taylor, ditch the skinny unsafe tires and opt for something like 165 or 175 wide. Just match the same profile as the 145, like what's been suggested on this thread. 135 and 145 tires are way too scary on these cars in my opinion. Even thought that when I built my first one as a teen. If you insist on running 'em, no more than 20 or so p.s.i. will make a big difference. Ran mine as low as 15 and currently run 20... the car feels/handles/brakes the best in the 18-20 range. But everyone's results will vary, of course.

Be safe in those Cal Lookers with Smart Car like tires, people... very scary stuff in an emergency situation. 

[NoBars]

I use a brake bias adjuster to keep the brakes balanced in a hard braking situation.

[Zach Gomulka]

I think the biggest advantage in modern tires is the technology, not necessarily the extra width.

What shocks are you using? Weight transfer is also a very important factor.   

[Jon]

I'm doing what SOB did, adjust the brake bias. Make the rear tires work for a living. The optimal breaking is somewhere between free rolling and fully locked, this suggests to me that bumpsteer will also take away some breaking power.

[Bendik]

Jon; Am I correct in thinking that SOB used bigger brakes in the rear, but no bias adjuster? I am setting up my oval with 60s brakes in the front and T3 in the rear and hope to achieve what You are describing.

[nicolas]

yes better brakes at the back will help 'unload' all the braking power from the front, but non the less the 135's are not optimal. i had 145's on my type3 and that is way too skinny, now i opted for a To#¤ta prius tyre 165/65/15 pretty low profile, 165/70 would be ideal, but i like the look and the improved braking was the biggest benefit. also rake, isn't helping on our cars either.

[Jon]

Bendik; Yes he used beetle disk brakes in the front and type 3 drums in the back, but also a bias adjuster. I actually found his actual break system in my barn on Sunday. I havent touched the adjuster, want to try it out first.

[Bruce]

Drums have more tendancy to lock up than discs, so a disc upgrade will definitely help.

[stoneloco808]

I ran into this problem many times, braking hard and going straight.  What does one recommend for those 3-1/2 inch wide wheels?  A friend of mine mounted 165s on his.  I swear it looks odd.  I currently have 125s on my 3-1/2 inch wide wheels, I say it looks perfect, sidewall is not bulging out like how it would with 135s and 145s.

[Lids]

Lower the front tire pressure to 18psi, psi is all about axle weight.

[Taylor]

OK guys, thanks for all of the suggestions.   

1.  Steve, it wasn't really that scary just surprising.
2.  I had the fronts at 24psi, ill lower it to 18-20.
3.  Front shocks are lowered oil shocks.

Maybe some wider fronts will be in order.

[Jim Ratto]

Nice thing about decrease in rolling radius is you increase leverage to the brakes vs a higher aspect ratio, with all else remaining equal

[draven898]

upgrade to disc brakes buddy !

[Hecker]

Taylor,
How was that for a wild ride...Glad to read that  you are not talking about needing some bodywork to be done on your Dad's car.
Did you both head for the TP when you got home, there had to be some in your pants.

Steve

Kinda reminds me of a guy who wrecked his split window 35 years ago !! I saw it spin and years later
met the driver......One wacky Steve Walker  !!!   

[andy198712]

Bendik; Yes he used beetle disk brakes in the front and type 3 drums in the back, but also a bias adjuster. I actually found his actual break system in my barn on Sunday. I havent touched the adjuster, want to try it out first.

is it a wide 5 setup? as i understand it, the wide 5 T3 drum has a built in hub but the 4x130 needs a hub also....?

[Eddie DVK]

Nice thing about decrease in rolling radius is you increase leverage to the brakes vs a higher aspect ratio, with all else remaining equal

Is this so?
I always toughed decreasing front tire pressure will cause a tendency for more understeer during cornering.
So better braking but worse steering...

I know... I know who needs to corner, but if you like daily driving with your looker...

I really get the look, but not the skinny tires in the front.
I drive with 165/65/15 up front(with discs), brakes good, corners good... also looks good in combination with 195/70/15 in the back... but that is my opinion.

Keep it save

Regards Edgar

[modnrod]

I guess it all depends on where you drive and the conditions.

There's no way I'd drive on 135s, but that's a personal decision for me. I quite often NEED minimum braking distances to avoid wildlife and swaying trucks road trains, so I need more rubber and more leverage on it. I also drive on loose ball-bearing gravel everywhere too though, so if I go too wide on the front then it wont dig in for grip, and the front will just slide straight off the road.

I would prefer 195s on the front for the highway, but then it skids on the gravel because the front is too light for the width, 155s on the gravel are great but then it locks up on a wet highway. Between the two is the sweet spot for my conditions.

[Bendik]

Bendik; Yes he used beetle disk brakes in the front and type 3 drums in the back, but also a bias adjuster. I actually found his actual break system in my barn on Sunday. I havent touched the adjuster, want to try it out first.

is it a wide 5 setup? as i understand it, the wide 5 T3 drum has a built in hub but the 4x130 needs a hub also....?

Yes a wide 5 set up

[Zach Gomulka]

I guess it all depends on where you drive and the conditions.

There's no way I'd drive on 135s, but that's a personal decision for me. I quite often NEED minimum braking distances to avoid wildlife and swaying trucks road trains, so I need more rubber and more leverage on it. I also drive on loose ball-bearing gravel everywhere too though, so if I go too wide on the front then it wont dig in for grip, and the front will just slide straight off the road.

I would prefer 195s on the front for the highway, but then it skids on the gravel because the front is too light for the width, 155s on the gravel are great but then it locks up on a wet highway. Between the two is the sweet spot for my conditions.

I agree, with 195's on the front of my old 67 it hydroplaned more than once. I think 185's are the best if your concerned about braking and handling on a daily driver.

[Jon]

Bendik; Yes he used beetle disk brakes in the front and type 3 drums in the back, but also a bias adjuster. I actually found his actual break system in my barn on Sunday. I havent touched the adjuster, want to try it out first.

is it a wide 5 setup? as i understand it, the wide 5 T3 drum has a built in hub but the 4x130 needs a hub also....?

SOB had a 5x130 setup, so separate hubs and drums at the back. And homemade (?) spindles up front.

[hotrodsurplus]

Drums have more tendancy to lock up than discs, so a disc upgrade will definitely help.

That's probably the disc brake's greatest asset yet few people understand that. A disc tends to offer more modulation than a drum. A drum brake's force increases exponentially whereas a disc brake's force increases in a more linear fashion.

The tread across the 5.50-16 tires on the front of my roadster are only .25" wider than a 135 tread yet I can stand that car on its nose without locking a wheel. Of course weight transfer is much better in my car than a Beetle but that underscores the idea that it's not just the tire size that you're fighting.

I always toughed decreasing front tire pressure will cause a tendency for more understeer during cornering.
So better braking but worse steering...

You WANT to induce understeer on a Beetle, especially a swing-axle one. They oversteer like crazy. In fact Volkswagen added the front antiroll bar to induce understeer. Reducing tire pressure isn't the best way to induce understeer on an early Beetle but sometimes you have to use any means necessary.

By the way, reducing the front tire width also induces understeer. So if we really worried about inducing understeer then the last thing we'd do is install small tires up front. 

[javabug]

Reducing tire pressure isn't the best way to induce understeer on an early Beetle but sometimes you have to use any means necessary.

I don't think it's a way to induce understeer at all. Reduce the front tire pressure, front tires have more traction. When the front has more traction than the rear, that's oversteer. To induce understeer and get the front tires to wash out, they need to lose traction. Pump 'em up hard, or add the sway bar.

[hotrodsurplus]

I don't think it's a way to induce understeer at all. Reduce the front tire pressure, front tires have more traction. When the front has more traction than the rear, that's oversteer. To induce understeer and get the front tires to wash out, they need to lose traction. Pump 'em up hard, or add the sway bar.

You're right that reducing tire pressure increases a tread's traction potential; however, that potentially increases longitudinal traction.

Reducing tire pressure also increases a tire's slip angle. Slip angle is the difference between the angle that the wheel points in a turn and the direction that the wheel actually follows. A softer tire is more prone to roll over in a turn and when it rolls over it loses traction. That induces slip angle. Vastly overinflating a tire will also increase its slip angle but you have to get to rock-hard pressure (like maximum inflation pressure on the front of a light car like a Beetle) to get there.

[javabug]

You're right that reducing tire pressure increases a tread's traction potential; however, that potentially increases longitudinal traction.

Reducing tire pressure also increases a tire's slip angle. Slip angle is the difference between the angle that the wheel points in a turn and the direction that the wheel actually follows. A softer tire is more prone to roll over in a turn and when it rolls over it loses traction. That induces slip angle. Vastly overinflating a tire will also increase its slip angle but you have to get to rock-hard pressure (like maximum inflation pressure on the front of a light car like a Beetle) to get there.

Well if we're going to discuss longitudinal traction, let's not ignore the fact that increasing the tire's slip angle invertedly decreases the rim's fractional width ratio to the bead of the tire versus the swept area of the brake pad caliper shoe. This then transmits the inertia's momentum to the backbone unibody structure of the front leaf torsion beam and affects the tire's contact patch with the road surface, causing further loss of gription. As you can now see, the simple act of discussing reduced tire pressures affects the entire characteristic of the car's handling, and most importantly that the keeping of ... an amphibious mammal for ... domestic ... yeah, that ain't legal, either.