Kart vibrates under acceleration

[Wyatt]

Hey guys, new here.

I recently picked up an old Carter Brothers model # 1755

It's powered by a stock Predator 212 and has a Comet TC-88 torque converter, 4.5 drive ratio and 18 inch tall rear tires.

My problem is, recently in the last hour or so of riding I noticed a distinct vibration under acceleration and a loss of acceleration through out the whole rev range. The engine sounds completely healthy to me.

I retentioned the chain and cleaned and lubricated the torque converter. I'm suspecting it could be my drive belt but I can't tell if it's significantly worn or just pretty worn out. I'm new to all this!

Should I replace the belt? The kart still rolls as easy as ever so I don't suspect a bearing yet.

Thanks everyone!

Wyatt

 

[frostyflammable]

The 4.5 drive ratio sounds low, with 18" tires 6:1 should be minimum. Not sure if that is the root cause but could cause the belt to wear faster.

--Dan

 

[Wyatt]

The 4.5 drive ratio sounds low, with 18" tires 6:1 should be minimum. Not sure if that is the root cause but could cause the belt to wear faster.

--Dan

Thanks, it's a 7 inch driven pulley. I believe at full lock up the torque converter is a 1.4 gear reduction.

Do you think that belt is worn out? I honestly don't know.

 

[mckutzy]

That won't matter much... It's the final ratio that counts... Hence the shudder...

Might want to even shoot for 7-8:1 as that will minimize belt wear..

 

[Wyatt]

That won't matter much... It's the final ratio that counts... Hence the shudder...

Might want to even shoot for 7-8:1 as that will minimize belt wear..

Just started happening to me recently. If it's just belts I don't mind replacing them.

 

[mckutzy]

Ok change the belt... .were also saying.. youve got a bit of a gearing issue...which could cause problems later...

 

[anickode]

I push 4.8:1 with 15" tires on a very light kart, and I feel it's about all the 30 series can muster. Different TC, I know, but I do agree your gear ratio might be a bit tall. A new belt may fix the vibration, but you can expect an overall shortened belt life.

 

[itsid]

the TC88 is essentially the weakling version of a series 20..
(liek the CAT)) is the weakling version of a series 30)

no way it can handle as much abuse as a series 30
(which is nearly identical to a series 20 apart from the benefits of an asymmetric belts)

So no, your narrow 5/8" belt is likely not able to transmit nearly enough power to the driven pulley to powre the axle with that high of a gear ratio (and those huge rear wheels)

And that's why your belt slips and burns (and those are clearly burn marks IMHO!)

So yeah.. 7:1 (or lower!) gear ratio is what you'd need..
6:1 on a series 20 might (just!) work; on a TC88 it surely won't.

'sid

 

[Wyatt]

Okay, thanks everyone!

So perhaps I should go to a 40 series or 30 series? I wanted to upgrade my Predator 212 with one of those stage 2/3 kits that advertise 15+ horsepower.

Perhaps I should jump straight to the 40 series? I like the top speed I have. I hit right around 40 mph at 5,000 RPM since I backed out the throttle stop screw on my 212.

---------- Post added at 11:32 PM ---------- Previous post was at 11:28 PM ----------

https://photos.app.goo.gl/aYerPjH1A25jB5x57

With the current setup on my kart I'm just not sure how I'd adapt a new torque converter to the jackshaft setup it currently has. I guess this is called an inboard driver? Or is it outboard? Hahaha!

---------- Post added at 11:38 PM ---------- Previous post was at 11:32 PM ----------

http://www.bmikarts.com/PDF/Carter-Bros/CarterBros/Model-1755/1755.pdf

That's a link to the parts break down for my kart. Weirdly enough, it says that it should have a 20 series but the part number for the belt comes back as a TC-88. Could the previous owner have bought the wrong belt?!
•MERGED•
The back of the driven unit. 3/4 jack shaft.

https://photos.app.goo.gl/g415rAjrZjiSQpTy6

 

[mckutzy]

Just direct upload... It's a pain for alot of us to go looking through 3rd party sites.

http://www.diygokarts.com/vb/showthread.php?t=737

 

[itsid]

Just direct upload... It's a pain for alot of us to go looking through 3rd party sites.

http://www.diygokarts.com/vb/showthread.php?t=737

THIS!

And also please edit your posts if you only have another image to add.

double posting is frowned upon

So as a rule of thumb..
if noone replied.. edit old post instead of adding a new one whenever possible

'sid

 

[Wyatt]

Sorry guys, I was on my phone!