The Bird Baja revival

[itsid]

Well the weakest part of a differential (or any transmission) is the gear,
any given geartooth to be precise...

As long as power transfer is through said geartooth it's as weak as the original diff or gearbox.
even if you weld the contacting surfaces of the gears (fusing the axles) you'll most likely have less material transfering the power than with a solid axle, thus in the end it can break much more easily.
although to be fair, it's very unlikely to break having everything locked and fused.
plus it's quite possible that you created a slight distortion and end up with a wobbly axle.

And counting in the price for a diff like that (even a good used one)
it's cheaper to buy a live axle, less hassle, less likely to fail.
a 1" axle costs ~ 50 bucks (25 axle plus a new sprocket and hub @ BMI p.e.)
the diff 150..(used; ebay#171342472490)
the bevel gears in case you want to replace them ~30 each (new, similar ebay#291000131861)...

it's up to you, but for me it just doesn't sound like a good idea at all

'sid

 

[freakincage]

Thanks again for the input. We used to weld diffs on our cars back in the day and never really had problems. Occasionally someone would blow a rear end, but that was usually due to racing. I didn't realize that these diffs were actually that costly. Soooo, now to think about a true live axle. Is there really anything special about the axle shafts listed at BMI? Shipping to Canada is what kills me. Just the shaft is going to cost well over $100. It's just C1018, 1" keyed round bar that's threaded on the ends right?

 

[itsid]

oh yes.. my fault.. haven't noticed your location

http://www.kartsandparts.ca/store/search.php?mode=search&page=2
is easier on the shipping I assume
or
http://www.kartworks.ca/

ah well, you'll find something.. even a mower shop has live axles I believe,
so maybe you can just pick one up locally

'sid

 

[freakincage]

The stock diff is 38", locally I can get a 36" piece and thread the ends myself. Will 36" be long enough? Has anyone ever used this keyed stock from Princess Auto?
http://www.princessauto.com/pal/en/Drives/1-in-x-3-ft-Keyed-Shaft/8079758.p On a side note, I love the Princess Auto brand name "Power Fist"...makes me giggle.

 

[freakincage]

Two more questions.

1. If I switch to a live axle, my understanding is only one rear brake will be needed and if I stick with a differential, I will need 2 because of the independent axles. Is this correct?

2. Currently there are 4 axle bearings. 1 each side of the kart close to the wheels and 1 each side of the diff carrier. If I do switch to the live axle, can the bearings near the carrier be eliminated? The axle shaft will be 1"x38" long.

 

[itsid]

1. Correct.. BUT since you have two already.. I'd keep both, chances are the manufacturer made them smaller than you'd need with just one

2. Theoretically.. yes... practically no.
The engine mount (with the bearing retainers) is most likely the fixed point for your brakes.. correct?
If so you want a third bearing right there as well, for maximum stability while braking.
Also, a third (or in this case fourth) bearing near the sprocket is always a good idea, for the very same reason; maximum stability, thus maximum power transfer

With sprocket and drum in the center of the axle you want the extra bearings.

Oh if you have the chance, why not even step up to a 1.25" axle?

'sid

 

[OzFab]

Keep in mind that locking the diff, by whatever method, will affect the steering...

 

[freakincage]

Thanks so much for the info. I know that a fixed axle will increase the turning radius. The areas that this will be driven are grass and gravel, so I don't think it will be so bad for turning.

I'm still on the fence as to whether or not I'm going to keep it as is, lock it or switch to solid axle. It all depends on what the diff looks like inside. I split it tonight but wasn't able to get everything cleaned and inspected. If there are grooves in any of the gears, i will lock it or switch it out.

Thanks again for all the great input you guys.

 

[OzFab]

I know that a fixed axle will increase the turning radius.

That's not exactly what I meant...

When I built my daughters kart the steering was non existent until I replace one of the locked wheels with a free spinning one, at which point, the steering was fine...

 

[zbuck]

Thanks for the constructive criticism. I chose that location for the fuel tank mainly because it was convenient and simplistic. This kart is for my son and is going to be a a top speed of about 15mph, once I allow it to go that fast. The size of the kart is also deceptive. If a child is driving it and somehow ends up upside down, the cage will protect them, an adult will be on their head.

This is a fozzy locker.
http://www.offroaders.com/tech/Lincoln-Lockers-Fozzy-Locker.htm

You are Welcome. Thank you for the links on the Lincoln/Fozzy lockers.

 

[freakincage]

No problem. I thought the fozzy locker could be a viable option as off-road lawn tractor guys like to use them. Anyway a little update. I took my axle shafts, with wheels still attached, to a machine shop close to my work to be pressed out. No problem they said. No charge they said. Anyway long story short, they put the one in the press and I don't know what they did but they messed up about half an inch of the axle nut thread and didn't get the axle pressed out. Now it was going to be $50 per side. F that I said, took my pieces home and bought a cheap air hammer/chisel. After about 2 hours of messing around, the one axle has been separated from the wheel. What a gong show that was.

Now on to the other side. Unfortunately, I'm going to have to cut off the band brake drums because they are just as seized as the wheels. I can't see them being very usable after being hammed off...so I am now planning disc brakes. These ones. http://www.princessauto.com/mobile/product/productDetail.jsp?name=Disc+Brake+Assembly+Kit&productID=8404360. The cost of this quick build is adding up fast in both time and money. When I first picked this thing up, I didn't think it was in this rough of shape.

EDIT: I started with the air hammer on the second axle and the drum fell off on its own. Maybe there's still hope of getting the first one off. If it bends a bit maybe I can straighten it out. I see a light at the end of the tunnel....I don't think it's a train.

 

[freakincage]

I got the second axle seperated from the wheel today and was able to get the other brake drum off. It did warp a bit but I'm sure I can straighten out with a block of wood and a persuading hammer. Each axle took about 2.5 hours to separate. Heat, quench with on blaster, air hammer on the axle from one side then the other, each time it moved a bit more until all the way out. The woodruff key for the drums is still stuck in each axle.

Next step is clean up everything and reassemble the diff if the gears look good. Would high heat bearing grease be an acceptable lubricant? If not, what do I need?

EDIT: FYI for those with the same question about grease. After a bit more searching/research, it seems that the recommended grease for these units is "bentonite grease" because the peerless axles and transaxles have no seals in them. This grease is a high heat grease that is suitable for applications where water is present.

 

[freakincage]

Got the axles and diff all cleaned up. You can see where the machine shop messed up the threads on the one shaft. I got it fixed up the best I could and the trheads do go about 1" past the rim hub, so I think it will be ok. I might add a cotter pin to each side to keep the nut from backing off, eventhough I don't think they will. Better safe than sorry. Also the diff housing and the gears look to be in decent shape, so I will leave the diff stock...unless someone sees something I don't. If you do, please speak up.

 

[freakincage]

Not very productive lately with work and kids. I did get the rear axle back together, the sprocket painted and the bearing hangers painted. I hope to get the axle back in this weekend. I used this stuff called "krazy grease" for the diff. I read a bunch of reviews about it and it seems like decent stuff.

 

[buckwill]

while u have it apart why not drill a 1/8th npt hole and add a grease zerk, every once a while squirt some grease in there, and yes high temp grease is ok for that service , doesn't have to be high heat,, not much heat in there, chassis lube is fine,, 25 year millwright machinist,, gas and steam turbine millwright, ex navy viet vet, disabled retired
buck

 

[buckwill]

if you built a roll bar for the little girl,,, build a roll bar for that gas tank too,, if it rolls first think to hit is the gas cap spilling fuel,, one spark and u have fire, dune buggies and trucks here,(welding rigs have done that,,)lost some friends in that exact snenairio,, sorry for the image,, buck

 

[freakincage]

I had thought of putting a zerk fitting in the diff but didn't. I figured if the orginal grease stayed in this stuff should too. It's advertised as for marine use as one of its applications and if it starts to seep out the bushings, I'll pull the diff and add a fitting.

Like I posted earlier, the size of this kart is deceptive in the pics. With the chassis sitting at 4 1/2" off the ground at the highest point, the speed this will be able to go, and the locations this will be driving in, a roll over is beyond unlikely so the fuel tank will not be caged. On a machine that would be going off road for sure I would. This machine will be only on flat ground of gravel and grass.

On to the progress, although minimal, it's moving forward. I got the steering system and front wheels painted and installed. I also got the rear tires off and rims painted. Those tires were a pain to get off the rims and it's no wonder that they leaked from the beads as they are chewed up in a couple of spots from whoever took the tires off before me, so I plan on tubing them.

My tires are 18 x 8.50-8 and I can't find a tube that size, although I haven't done a full blown yellow pages search, would a 18 x 9.50-8 tube work? I realize that it's a bit larger, but not by much, is it really that critical in this application?

Here's some pics of progress and a couple mock ups with rear tires and engine.

EDIT:
For brakes, I will use the band brakes that came with it for now and I will order new bands. The one drum is slightly warped, but I can easily straighten it out, then clean and paint them (except the part that the band rides against.

 

[freakincage]

90% Complete...This is a long post and I have a problem.

Alright, it's been a while and progress has been slow. I feel that this thing is 90% complete and I should have it driving by this weekend. I still have to replace the brake shoes, but they will be fine for a short time. My son is so excited that almost every day I hear "can I drive it now?"

Here's the way it sits now. A long way from where it first started.

I still need to cut a 3/4" plywood seat back, cut the seat cushions to fit and my mother has offered to sew a new seat cover. The seat cushions are in 4 separate pieces right now as they are compiled of foam from of 2 separate automotive bucket seats.

The engine is running a custom intake and exhaust made from 3/4" black pipe, regular small engine muffler and a offshore carb for a 110cc and whatever else engine. I thought I would have to rejet, but after playing with the mixture and idle screws running it at 3400 rpm for a few minutes and pulling the plug, it all looks good. Sorry no pic of that. The throttle is weird though. When I push the gas to where I have the stop set, it revs to about 2100 and then slowly "accelareates" to 3400. Any Ideas as to why?

The gas and brake pedals are both quite similar in construction. The have springs to return the pedal and I have added a stop on the gas so the engine can not be reved past 3400 rpm.

The brake is a single cable off the pedal (e brake cable from a forklift) and splits into 2 about mid chassis. The red splitter is mad of three 3/8" nuts welded together and a cap to sandwich the cable balls (for lack of a better term) in position. The cables are automotive throttle cables and are the same thickness as the old ones.

Since my son is too short to reach the pedals, I have made some adjustable pedal extensions. Sorry about the pic quality.

At the recommendation of someone here, I am using a tach, since the governor has been completely removed. I got a cheap one on Amazon. Really simple to use and install. Wrap the tach wire a few times around the spark plug wire, zip tie it in place and find a place to mount the display. When the engine is not running it displays total hours of use. I plan to mount the display on the steering hoop above the steering shaft.

I've also installed two kill switches and a fuel shut off valve. The firs or master kill switch is located behind the driver, just below the fuel tank (the silver dot on the second pic of this post) and the second is a push button just below the steering wheel. It too is repurposed. It's a trunk release button from an old Pontiac.

Now for my problem. I has to do with the torque converter. I believe I have a Comet 30. Asymmetrical, 3/4" wide, 6" driven with a green spring. The C.D. is 6-5/8". I purchased a genuine Comet belt (model 203589). The belt chart on the package says that this is the belt for a 30 series, 6" driven with a C.D. of 7".

When I install the belt on the backing plate, it sits nicely on the brass bushing. When I install the outer clutch assembly, it goes tight on the belt thus engaging it. It seems that if the backing plate and clutch face were an additional 1/8" apart, the belt would sit properly. is there an additional spacer that I am missing? I still have to do a bit of tweaking to get the pulleys completely in line, but how they are now shouldn't affect the belt like this. Any one have any ideas on how to fix this?

 

[freakincage]

Got the tach display mounted and got the other small issues worked out. Went on the test drive tonight and the kart works pretty much flawlessly. I don't know the top speed, but it feels fast at 3400 rpm. Since it's for my son it will be limited to somewhere around 2500 rpm for now.