Got some new wheels: Boss 338's in 20x10 and 20x8.5

[lolife99]

OK guys,... I may have this figured out.
Look at the first pic that member "Hickup Pickup" posted.
Look at the length of the center hub in relationship to the length of the lug studs.

Then,... look at the second pic that member "mentlmidget" posted.
If the center hub of the "light duty" 1" thick rotors is shorter,... that may cure our problems.

I'm going to the parts store tomorrow to purchase a 1" thick rotor and see if it will work on my 20x8.5 Boss 338's.

I'll keep everyone posted!

[mentlmidget]

Morning y'all

I quick dash to the truck and here is the following:
1 inch thick rotor
2 inch distance from braking surface to wheel mounting surface (aka height of rotor hat)

[SCOTI]

That sounds like the difference.... 1" Lt duty vs. 1.25" standard rotors. Mentlmidget, what's the measurement from the face of the hub (where the studs seat) to the end of the hub 'snout' (where the dust cap seats)?

In those pics, the hub snout also looks to be a smaller OD vs. the other rotors in the previous pics.

[lolife99]

JACKPOT!
Finally figured out what Boss Wheels did.
They designed these wheels to fit the 1" thick "Light Duty" rotors.

I had the answer under my nose all the time.
After seeing mentlmidget's pics (thanks again for posting and helping me solve this issue),... I decided I was going to go to town and buy a new 1" thick LD rotor to try my wheel on.

Then I remembered my extra '83 swb chassis I have. Luckily it had the 1" rotors on it. So,... out I go first thing this morning to check the fit.

THAT'S IT!
Done.
Problem solved,... for me anyway.

I hadn't order my new drop spindles yet for my '86 Dropmember Project,... but now I know to get the light duty version from Belltech.

This does cause a problem with me putting these wheels on my '69,... since I already have the 1.25" thick rotors on it.
It also means that anyone wanting to put the OLD VERSION of these Boss 338 wheels on a 63-72 with a 5-lug conversion,...
will have to use the 73-87 only, 1" thick rotor drop spindles or use a set of factory stock height 1" thick rotor spindles.

You can also see where the stock dust cover pushed out the Boss centercap about 1/8".
I think this can be fixed by using a hammer to dent the cap.

To say I'm happy is an understatement!

[lolife99]

mentlmidget,...
Out of curiousity,... does your truck have the "light duty" 1" thick rotors?
The hub area looks shorter on your rotors than
the pics that member Hickup Pickup posted.

[smashingchuck]

Nice work Keith.

[lolife99]

This won't solve everyones issues,... but at least they will fit something.
And,... I don't have to return mine or wait for the new design.

[djracer]

I hope I don't have these issues on a mustang II rotor. I bought these in a 18x8 and a 18x9.5 for my brothers 59 truck. We have the rears on and haven't done the fronts yet.

[71'tahoe]

I did some digging and ithink the 88-98 trucks are like the 73-87 trucks they used 2 different rotors depending on the option or the gvwr. i may head to the parts store and pull a few rotors and measure..

[72SWBURG]

Originally Posted by djracer

I hope I don't have these issues on a mustang II rotor. I bought these in a 18x8 and a 18x9.5 for my brothers 59 truck. We have the rears on and haven't done the fronts yet.

What size Rubber did you go with??

[72BlckButy]

Awesome FAQ Keith!

[Hart_Rod]

Keith - quick questions, I'm getting ready to buy new spindles and am thinking about going with the LD ones. What else has to be changed besides the rotors and spindles to make the LD stuff work? Thanks,

R/

[lolife99]

Rob and Benji,... the only thing I'm not sure about is the calipers.

I need to stop by the local auto parts store and check that out tomorrow,... but I'm sure they are a different part number.
If I had DSL,... I'd look online,... but it's not worth the effort. (And the slow internet, driving me crazy)
My frame is a 1983,... so that's the application I will use.
(Hint, hint dsl guys)

Last night I ordered a set of 73-87 Belltech 3" drop spindles (part #3200 for the LD version), for my '86 Dropmember project.

Anyone else running 63-70 conversion spindles will have to swap to the 73-87 version and change balljoints.

I think the upper and lower balljoints of the 71-72 trucks will work with the 73-87 spindles,... but I'm not 100% sure.
(another cross reference item for you dsl guys)

I'm pretty sure there is no 1" spindle for the pre '73 trucks,... so a balljoint/tie rod switch will be in order.
(with maybe the exception being the 71-72 trucks)

[mentlmidget]

GUYS! please remember that going to a 20" wheel combo is going to be double, if not triple the weight per wheel. Braking distance IS INCREASED. Before ordering all the brake hardware, think about increasing the rotor diameter, which would also include a different caliper/spindle setup. I am all for the GO GO GO, but we also need to STOP STOP STOP.
I didn't think there was going to be that much of a difference from the 15" 165/50/15 combo I had until I went out to do this measuring. Holy cow was that wheel heavy. I am a school teacher who used to work at a few tire shops in my younger years. I equal the weight to about a split rim set up for a box truck. Maybe not quite that bad, but heavy enough.

I AM looking into getting a bigger brake combo for my rig.

Just keep the longer stopping distance in mind.

[brossow]

Originally Posted by mentlmidget

GUYS! please remember that going to a 20" wheel combo is going to be double, if not triple the weight per wheel. Braking distance IS INCREASED. Before ordering all the brake hardware, think about increasing the rotor diameter, which would also include a different caliper/spindle setup. I am all for the GO GO GO, but we also need to STOP STOP STOP.
I didn't think there was going to be that much of a difference from the 15" 165/50/15 combo I had until I went out to do this measuring. Holy cow was that wheel heavy. I am a school teacher who used to work at a few tire shops in my younger years. I equal the weight to about a split rim set up for a box truck. Maybe not quite that bad, but heavy enough.

I AM looking into getting a bigger brake combo for my rig.

Just keep the longer stopping distance in mind.

Let's not get into a panic here. Do you upgrade your brakes if you're going to have a passenger in your vehicle? Didn't think so. The rims weigh more, but the tires weigh less. And we're talking about a 2-ton vehicle, not a 500-pound motorcycle. Yes, there's a difference in rotational mass, but overall the weight difference is negligible in the big scheme of things on a vehicle this size. (If you want to do the math, an increase in rotational mass equates to about a 10x increase in static mass -- for example, adding 40 lbs at the wheels is roughly the same as adding 400 lbs of cargo.) If your braking system is so close to its limits that the weight of the wheels means life or death, you've got bigger problems than wheel selection.

I agree that brakes need to be a MUCH higher priority than just about anything else on a vehicle. But I don't see adding a few pounds per corner as something that necessitates a $2000 brake upgrade. IMHO, of course.

Brent

[vegaschevy]

Originally Posted by brossow

Let's not get into a panic here. Do you upgrade your brakes if you're going to have a passenger in your vehicle? Didn't think so. The rims weigh more, but the tires weigh less. And we're talking about a 2-ton vehicle, not a 500-pound motorcycle. Yes, there's a difference in rotational mass, but overall the weight difference is negligible in the big scheme of things on a vehicle this size. (If you want to do the math, an increase in rotational mass equates to about a 10x increase in static mass -- for example, adding 40 lbs at the wheels is roughly the same as adding 400 lbs of cargo.) If your braking system is so close to its limits that the weight of the wheels means life or death, you've got bigger problems than wheel selection.

I agree that brakes need to be a MUCH higher priority than just about anything else on a vehicle. But I don't see adding a few pounds per corner as something that necessitates a $2000 brake upgrade. IMHO, of course.

Brent

I laugh when people make this argument. Like when they pull that 2 ton trailer, or load the bed that the truck was okd to haul. or when you put the 5 passengers in the vehicle. better upgrade your brakes ASAP

[lolife99]

Good luck finding a rotor,... ANY rotor,... that will fit this wheel.

So far the Light Duty version of the stock rotor is the ONLY one that will work.
And that's what you have right now.
Let me know if you find another rotor/brake system that this wheel will fit.

[lolife99]

I'm good with a brake upgrade,... but until they redesign this wheel,... they won't fit anything except the factory LD rotors.

I guess I was just happy to get them to bolt on with no modifications,... finally.

You guys keep me posted if you find another rotor that will work,... or a new part number for the redesigned wheel.

[mentlmidget]

I am not panicing, nor am I suggesting there be a panic. I am only stating, since I have put the 20's on my truck, my stopping distance has increased. I wouldn't consider myself a maniac on the road, but then again, this is subjective.

[brossow]

Originally Posted by mentlmidget

I am not panicing, nor am I suggesting there be a panic. I am only stating, since I have put the 20's on my truck, my stopping distance has increased. I wouldn't consider myself a maniac on the road, but then again, this is subjective.

Yup, and that's an expected occurrence -- same as if your fat cousin Cheeto is along for the ride. Something to be aware of when you're driving around getting used to the new wheels, but not something that should necessitate a brake system upgrade.

[DrtyJack75]

well I was just looking at the ECE page and the brake conversion they sell (and I bought) have a 1.25" rotor.

So is it possible to just go back to the 1" or is there something to do with the newer spindles that you have to have the 1.25" (or heavy duty)?

[SCOTI]

Originally Posted by DrtyJack75

well I was just looking at the ECE page and the brake conversion they sell (and I bought) have a 1.25" rotor.

So is it possible to just go back to the 1" or is there something to do with the newer spindles that you have to have the 1.25" (or heavy duty)?

You can machine the HD 1.25" rotors & use spacers to work w/these wheels if you can accommodate the slight increase of track width.

[lolife99]

Originally Posted by DrtyJack75

well I was just looking at the ECE page and the brake conversion they sell (and I bought) have a 1.25" rotor.

So is it possible to just go back to the 1" or is there something to do with the newer spindles that you have to have the 1.25" (or heavy duty)?

The only way to use the 73-87 1" LD rotor is to change ball joints and outer tie rod ends.
Your ECE "conversion spindle" eliminates all that.

It may be better to wait for the "new" design on the wheel itself.

[DrtyJack75]

Id rather not use spacers? Sorry if I missed it but is there any word on the release of the new wheels?

[lolife99]

Originally Posted by DrtyJack75

Id rather not use spacers? Sorry if I missed it but is there any word on the release of the new wheels?

I haven't heard anything yet.