Bobs 2024 Build Off Build

[Rat]

I have never in my 58 years of playing with cars heard of blowers being sucked dry of oil. I can’t even fathom how that could happen unless it was sized far too small and had to be severely over driven. Now maybe with a Paxton type supercharger that could happen. But not a Roots!!

I've only heard of it being an issue in a Turbo. It of course has nothing to do with "sucking" or not... it has everything to do with hot exhaust gasses turning the impeller and poor lubrication from a weak pump or a trash plumbing job. Either way the combination seizes the bearings or turns them into shrapnel and your TC tends to become irreparably toasted.

If you've got oil in your intake there's bigger issues to worry about than an exploding forced induction unit regardless of which one it is, last I checked a twin screw charger is cooled much the same way a 2cycle engine is... the incoming A/F mix and that's assuming it generates any heat.

A centrifugal charger might be different but either way you'd plumb it like you would a TC or even an oil cooler running from a remote filter.

Low pressure line out low on the case to the filter,
Low pressure from filter to remote pump,
High pressure from remote pump to cooler (or forced induction)
High pressure from cooler (or FI) back to case above the resting oil level

Replacing the low oil sensor wire bung with a brass fitting works great since it is just above or right at where the oil level should be, and if you have an electric starter then use a 90° to route downward, and if you need to clear the mount deck without kinking the line just sttick another 90° in the first one to kick it out the left side running parallel with the starter motor.

 

[Evanguy]

The reason these will suck the oil out of them is they are junk from China rebuilt with the lowest quality parts. Lots of them don't even work right out of the box or come part in a few hours. They are $200

Proper bearings good for 18k rpm would cost more then this whole charger does.

If you look at every single one of these that failed on the Internet it's due to coming part internally or runs low on oil and bearings/seals go.

Also they were never designed to be under vacuum

 

[Rat]

The reason these will suck the oil out of them is they are junk from China rebuilt with the lowest quality parts. Lots of them don't even work right out of the box or come part in a few hours. They are $200

Proper bearings good for 18k rpm would cost more then this whole charger does.

If you look at every single one of these that failed on the Internet it's due to coming part internally or runs low on oil and bearings/seals go.

Also they were never designed to be under vacuum

Seems like the actual smart thing to do is just not fuss with the extra BS. If you must as a challenge seeker then tear it down and rebuild the sh*tty rebuild before you try running it.

 

[Denny]

A properly sized and driven Roots blower is not under vacuum. Especially on a small 1 lunger.

 

[bob58o]

Roots Style Supercharger for a One-Lunger

Thumper Pumper

which may be a better name for this build than the fore mentioned “Mrs Esterhaus”

 

[bob58o]

Head Tubes? Steering Head?
What ever it’s called, I assume there is more to it than a straight tube with bearings. I have these bearings that came with the forks, but no head tube.

I have this tube. 6” long, 1.5” ID, 1.75 OD

I’m not sure if the easier solution is to make the tube work with the stock bearings, get new bearings to work with the head tube and steering neck, or try to cut the head tube off a z50 frame. The cheapest chassis I found on eBay was still like $200

 

[Denny]

Find a tube to work with the bearings. Or talk Terry into making you one.

 

[bob58o]

 

[Rat]

If I was in a position to fabricate a Headtube (you had it correct) I'd definitely want to do so in a way that allowed use of a roller bearing similar to automotive wheel hub bearings. They are easier to maintain than a loose ball set up, and handle all the various load angles better.

I've got a CRF70 (clone) front fork and steer tube with a bit of frame still attached. I haven't found a use for it yet because I don't build for 14" wheels.

 

[bob58o]

If I was in a position to fabricate a Headtube (you had it correct) I'd definitely want to do so in a way that allowed use of a roller bearing similar to automotive wheel hub bearings. They are easier to maintain than a loose ball set up, and handle all the various load angles better.

I've got a CRF70 (clone) front fork and steer tube with a bit of frame still attached. I haven't found a use for it yet because I don't build for 14" wheels.

It seems people have been installing tapered bearings in these as an upgrade. I don’t know much about the steering bearing options. I’ll watch some videos and read some threads.

 

[bob58o]

Features & details​

• Outer diameter: 41mm
• Inner diameter: 22.5mm / 24mm
• Suitable for applications that support both radial and axial loads
• Supports heavier loads than bearings with comparable-sized ball bearings
• Unsealed, made of chrome steel for durability and resistance to deformity under heavy loads

 

[Rat]

Features & details​

• Outer diameter: 41mm
• Inner diameter: 22.5mm / 24mm
• Suitable for applications that support both radial and axial loads
• Supports heavier loads than bearings with comparable-sized ball bearings
• Unsealed, made of chrome steel for durability and resistance to deformity under heavy loads

Tapered roller is exactly what I was referring to.

 

[Denny]

I like the tapered wheel bearings. Heavy felt would make a good seal to keep dirt out of the bearings. And add a grease zerk to the head tube to grease them without having to take them apart.

 

[bob58o]

Could I cut some sleeves of the 1.75” od tube, weld sleeves onto ends of 1.5” od tube, then bore out the first half inch or so of the sleeve?

41mm bore in 44.45mm tube would leave about 0.068” wall thickness to house the bearing. I think.

 

[ezcome-ezgo]

Yes, you could do that. Does it have to be all metric-y? Oh I found this:

HEAD TUBES MACHINED BMX STYLE IS42/42 — BICYCLE FABRICATION SUPPLY

4130 BMX HEAD TUBES FOR 1-1/8 STEER AND INTERGRATED IS 42 UPPER AND LOWER BEARINGS. GYRO TAB DRILLED AND NON DRILLED. SIZES AVAILABLE 110 , 115, 117 , 120 , 127MM

www.bikefabsupply.com

 

[Denny]

Could I cut some sleeves of the 1.75” od tube, weld sleeves onto ends of 1.5” od tube, then bore out the first half inch or so of the sleeve?

41mm bore in 44.45mm tube would leave about 0.068” wall thickness to house the bearing. I think.
View attachment 145581View attachment 145582View attachment 145583

Yes.

 

[bob58o]

Yes, you could do that.

Yes.

Im still unsure about the anatomy of the head bearings, steering neck, and and various caps and other parts.

If anybody could draw me a diagram showing how things might come together.

What am I not considering?
Do I need anything tapered in my head tube?

I understand the felt dust caps.
Would I need to use any other “things”?
Any of these stock parts?
What are the names of these components?

Upper race, lower race, inner race, outer race, dust cap, washer,…???

 

[bob58o]

 

[Rat]

Im still unsure about the anatomy of the head bearings, steering neck, and and various caps and other parts.

If anybody could draw me a diagram showing how things might come together.

What am I not considering?
Do I need anything tapered in my head tube?

I understand the felt dust caps.
Would I need to use any other “things”?
Any of these stock parts?
What are the names of these components?

Upper race, lower race, inner race, outer race, dust cap, washer,…???
View attachment 145592View attachment 145593View attachment 145594

#1 lock nut
#2 top bearing race/cone
#3 dust cap
#4 bearing cup
#5 bearing cup
#6 bottom bearing race/cone

#7 at 115mm steer tube

 

[bob58o]

#1 lock nut
#2 top bearing race/cone
#3 dust cap
#4 bearing cup
#5 bearing cup
#6 bottom bearing race/cone

#7 at 115mm steer tube

That 115mm is just a ball park figure.
Since the locknut moves and I’m not sure the length of the original head tube.

So the locknut clamps down on the head tube, but it seems as though the upper triple tree is supposed to sit on the top of the lock nut.

So I guess the tube length should be exact, but I think I could use some washers.
I think I need to get the bearings and find out exactly where they sit on the steering tube.

I think I thought about it enough. I should really read those threads I mentioned earlier. I think it was on planet minis or some forum I was unaware of.