My Design

[Simon Thomas]

Repair Plan

Attached is my plan to fix this problem. So far, I have no intention to change the threaded rod with other rods. Just let it be for the time being.

 

[Simon Thomas]

Longer Video and Closer Look

The closer look of my cart design can also be viewed at www.youtube.com/watch?v=qrDFUgvqRio. Just found the video and uploaded it a few days ago. The video was taken before I weld the bucket and before I broke the back threaded rod .

 

[machinist@large]

:toetap05:What you really need to solve the problem is a differential between the drive wheels. Without some way to compensate for the different speeds of the driven wheels when cornering on firm, hard surfaces, you'll continue to have problems with broken parts. A potential source for parts (for a differential that you might be able to adapt) would maybe be used garden tractor parts. Many of them have pieces that would be strong enough for your engine. I don't know what potential resources you have available, but here in the U.S. that's where I would start. The threaded rod is just the current weakest link. I would also recommend searching thru the threads on this sight; this topic has been discussed before. Good luck!!

 

[qtband]

I would just make it a one wheel drive. If you'r not going super fast, one wheel drive would be fine and eliminate the twists in your axle.

 

[Doc Sprocket]

Machinist and qtband make very good points, and I completely agree. You can repair that threaded rod until it's nothing but a 48" long weld bead, and it's just going to keep breaking. Even if it does survive the shear loads, it will not survive the torsional loads. You need a differential, a hardened shaft, or a one-wheel set up. The diff or dead axle (one wheel) are the preferred choices for handling.

 

[Simon Thomas]

:toetap05:What you really need to solve the problem is a differential between the drive wheels. Without some way to compensate for the different speeds of the driven wheels when cornering on firm, hard surfaces, you'll continue to have problems with broken parts. A potential source for parts (for a differential that you might be able to adapt) would maybe be used garden tractor parts. Many of them have pieces that would be strong enough for your engine. I don't know what potential resources you have available, but here in the U.S. that's where I would start. The threaded rod is just the current weakest link. I would also recommend searching thru the threads on this sight; this topic has been discussed before. Good luck!!

Hi Pat,

Thanks again for your view and I totally agree with you on the differential. Otherwise, I will continue to have a broken threaded rod over and over. Your suggestion is very helpful. I just knew that threaded rod is the current weakest link, which I did not take notice at all before.

I am new to this forum, hope you don't mind to suggest a simple differential from other threads. I will search as well.

Answer to your another suggestion; the used garden tractor is still expensive in Malaysia. I ever asked a shop that for an old, rusty and used unit, the price is still around RM3,000 (around USD1,000). Reason being was because they were imported to Malaysia. I know in the US, many DIY people would like to start with their used or old garden tractor. However in Malaysia we have no luxury to do that :biggrin5:.

 

[Simon Thomas]

I would just make it a one wheel drive. If you'r not going super fast, one wheel drive would be fine and eliminate the twists in your axle.

Thanks qtband. That would be last resort if I could not find any simple differential.

 

[fowler]

u could try small cars or even trikes

i dont know what they are called but they are those 3 wheeled things that get around india i dont know if u guys have them but a back axle outta one of those would work well

 

[Simon Thomas]

Machinist and qtband make very good points, and I completely agree. You can repair that threaded rod until it's nothing but a 48" long weld bead, and it's just going to keep breaking. Even if it does survive the shear loads, it will not survive the torsional loads. You need a differential, a hardened shaft, or a one-wheel set up. The diff or dead axle (one wheel) are the preferred choices for handling.

Good view as well. The threaded rod is quite long and have tendency to break like you said. I did not notice this before as well. All your suggestions and comments are great.

 

[Simon Thomas]

u could try small cars or even trikes

i dont know what they are called but they are those 3 wheeled things that get around india i dont know if u guys have them but a back axle outta one of those would work well

Fowler, I believe you referred to something like trisaw but run by the engine. I saw that in the Indian movie. Unfortunately I have no access to the design to help me with my problem.

If you have any stuff / photo for sharing, hope you don't mind to share with me. Thanks.

 

[Simon Thomas]

Question and Answer

Ouch!! Good thing you weren't hurt. That's one of the problems with threaded rod, especially where you welded the nut to it. I take it that this is the shaft that transmits power from the engine sprocket to both the rear wheels? Questions;


1)Do you have a differential of any sort in the system?

2)How far apart are the drive wheels?

3)How tight a circle can it turn?

Without a way to compensate for the speed difference between the inner and outer wheel in a turn, the problem is just going to return. Sleaving the rod or remaking it out of round stock would be better, but would only band aid the symptoms.

Good first build. Just got to get thru the teething phase.

Now have chance to answer you. Sorry for late reply.

1)Do you have a differential of any sort in the system? (NO. Rely on engine and wheel sprocket connected with the motorbike chain)
2)How far apart are the drive wheels? (Roughly around 2.5'-3'. I cut the second chain to add up to the first standard length)
3)How tight a circle can it turn? (normal tight, same when we tightening our motorbike chain) Photo attached.

 

[Simon Thomas]

Repair in Progress

I made some repairs to the rear threaded rod. First, I removed the broken part.

 

[Simon Thomas]

Repair.. repair..

Then I cut the broken threaded rod, and connected with two welded nuts as joint. I also added one unit of pillow block bearing beween the wheel sprocket and disc brake. Hope this will prevent the same broken rod incident again.

 

[Simon Thomas]

Repair finally done

This is the new look of the rear wheel joint, after some welding works. After test drive, it works well except that I need to be careful when (i) carry heavy load (ii) driving on bumpy and (iii) sticky muddy road condition. These three factors (so far from my observation) could break the rear wheel threaded rod.

 

[Simon Thomas]

Side Discussion: Multi Purpose Gasoline Engine

To new visitors, welcome to my thread.

FYI, I have updated my photo albums. I have 3 photo albums so far. The first two albums are for my buggy design from a scratch until it becomes a piece of useful vehicle.

I have added the 3rd photo album comprising the modified go kart engine @ gasoline engine where the local people at my area have converted / modified it as their watercraft / speed boat engine. At the other side of the world, the Thais have modified this engine as well (find under the name of "long tail shaft propeller") for the same purpose that could reach certain high speed. However, our local DIY people have managed to come out with their unique and brilliant design as well. I know this forum is on go kart or buggy, however I hope the viewers don't mind to discuss on other side useful discussion that is the other use of the go kart engine.

Feel free to comment but I believe you need to register as member first. Happy viewing, sharing and commenting.

 

[Simon Thomas]

Pump Ski Videos

To make this side discussion more interesting, I have added some videos to my thread:

1. My engine that could be converted to run my pump ski boat at http://www.youtube.com/watch?v=1nypcGhggJk.

2. The making of half complete pump ski boat at http://www.youtube.com/watch?v=LiHUD_TJna0.

and

3: The training by our pump ski boat owners at http://www.youtube.com/watch?v=kZ59MqsjT18.

Hope you find my thread useful.

 

[Simon Thomas]

Gasoline Engine RPM

If you follow-up my thread and check my album, I have a unit of 6.5 HP China made gasoline engine. It is my future plan to design a buggy or go kart and use the engine to run it.

However at present, I use it for my speed boat / pump ski. I believe my engine has standard 3,600 rpm. The question now is how to increase the rpm?

1. Based on some answers from our active members which I sent them private message, remove or by-pass the governor may help until 5,000 + rpm. Thanks to their answers. This is what I have done to my engine.

2. The other question is what if I change the original carburator with compatible motorbike carburator, can this increase the rpm? Some of our speed boat owners have done this which they said has increased the rpm. I have a doubt on this. If you know the answer, please let me know.

FYI, our speed boat has a limited space and cannot place heavy weight engine. Therefore, 6.5 - 7.5 HP gasoline engine is alway an ideal option. I don't plan to use higher HP due to this limitation. You can check my album if you want to know in detail.

Appreciate your feedback, if you know.

Thanks and regards,

Simon

 

[indianblood]

u could try small cars or even trikes

i dont know what they are called but they are those 3 wheeled things that get around india i dont know if u guys have them but a back axle outta one of those would work well

Its called auto here.

 

[Simon Thomas]

Indian Auto

Nath,

Thanks for photo. It's cool!! I know the Indian movie always have this vehicle. I believe they in Thailand also have something similar like this.

I have a few questions here regarding this vehicle:

1. This vehicle has any reverse gear?
2. Is it possible to see the rear wheel design (reason being was I broke my rear threaded rod before and some forum members have suggested to duplicate the vehicle in your photo to improve / strengthen that part). Hope it is not too much to request if you could provide me some photos as well.

Thanks.

 

[Simon Thomas]

2. The other question is what if I change the original carburator with compatible motorbike carburator, can this increase the rpm? Some of our speed boat owners have done this which they said has increased the rpm. I have a doubt on this. If you know the answer, please let me know.

Answers I received from some of you had the opinion that eventhough we change to other carburator, the maximum speed still float at 5,000 + rpm. I think this makes sense:toetap05:.