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Old 08-01-2003, 11:02 PM   #1
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Bottom end dies after 3 mins. What the...???

Car = V1RR
Engine = OS TR(P)

Problem with car losing all bottom end after 3mins. Here's my story of events that lead to this happening, and might include some hints as to the problem. Its a little long i know, and would appreciate any help. Thanks in advance.

PRACTICE (Australia NSW, Eastern Creek – 26th July 2003)
The car started the day off with good all round performance, until of course, the practice laps heated up, and you guess it, another car nudged me, and my car took a tumble about 2 or 3 times, and since then, the problems started. Grrr…From that point on, and for the rest of the day, my car seemed to have an unusually loud whistling type howling noise when the motor was running.

1st 5 min heat (18 laps – 1st place for most of the race, ended up 2nd after 3 last lap)
At the start and during most of the race, the car seemed normal, with good bottom and top end. But after about the 3.5 min. mark, the car lost all bottom end performance, but once 2nd gear kicked in, top end was normal. What the…??? After taking the body off, I noticed the motor’s carburettor came loose, and had half slid out. I pushed it back in, and then retightened the nut (without locktite). I also noticed that the ‘non-screwable’ nipple on the pipe where the back pressure hose for the fuel tank was loose, and perhaps, I’m not sure, letting out a small amount of exhaust.

2nd 5 min heat (0 laps - DNS)
Pre-race practice laps were good, but when the cars were released for the warm up lap, I didn’t even get 10 metres in, since it appeared that the pre-race practice laps again loosened the carburettor nut, and the carburettor was practically out. SO…I pulled the motor off the chassis, locktited and tightened the carburettor collar tightening nut, but noticed the screw that the nut goes onto, was being pulled through it’s ‘housing channel’ (if you know what I mean). What the…??? Don’t think I can do anything about this no...??? I also pulled off the car the 1st and 2nd plastic gears, lubed the one-way bearing on the 1st gear, and also pulled the metal gears off the motor and checked the clutch spring was still tightened and the bearings on the metal gear housing were spinning.

3rd 5 min heat (18 laps – 2nd place)
No pre-race practice laps this time. Again, for most of the race, the car was handling quite well, but towards the end of the 5 min heat, the car lost all bottom end performance.

Final
DNS…couldn’t be bothered getting frustrated towards the end of the race with no bottom end.

If any of you guys know of things I can start and check in addition to what I’ve already tried, any help would be great. Many thanks in advance
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Old 08-02-2003, 10:36 AM   #2
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Default Re: Bottom end dies after 3 mins. What the...???

Quote:
Originally posted by Glenn
Car = V1RR
Engine = OS TR(P)

Problem with car losing all bottom end after 3mins. Here's my story of events that lead to this happening, and might include some hints as to the problem. Its a little long i know, and would appreciate any help. Thanks in advance.

Uhm.... many things come to mine mind. Check in this order:

- Too lean low-end (if you need your car get out snappy of the turns, get this with gearing, not with too lean low-end). Overheats the engine. Just open 1/8 the low-end and see if improves. Check too the clutch bell endplay, probably you have too much and you're overheating the shoe.
- Losing compression on the P/S. Piston get worn and with high temps, sleeve gets loose losing low-end (strange, you didn't told anything about a bitch to carb engine). Check with a new P/S.
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Old 08-03-2003, 01:06 AM   #3
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Well two main things spring to mind:

1. The loose carb is not sealed right. This means an air leak and the temps of the motor climb during the run. The crank overheats and low end goes away big time.
2. The rod is worn. When the rod wears bottom end goes away on the motor.

Could be many other things too, worn clutch shoe, too lean bottom end like corser said. Have to eliminate them one by one, pull the car completely down and inspect each part. The work on the motor the same sealing the carb up fully.
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Old 08-03-2003, 10:09 AM   #4
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Make sure the idle screw is not open too much causing the motor to load up off throttle. I assume a leaky carb will cause the same.
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Old 08-03-2003, 10:18 PM   #5
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Moving forward...

How do you tell when the shoe is worn or melted as some say?

How can i make sure the carby is completely sealed properly?

ALso, i hadn't been greasing the thrust bearing? Do you guys? Could this also be contributing to the problem? The instructions didn't say anything about grease on the thrust bearing...

Thanks in advance guys

Last edited by Glenn; 08-03-2003 at 10:24 PM.
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Old 08-03-2003, 10:44 PM   #6
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Talking o/sTR.

This exact same problem happened to me with the o/s tr.
First .the os has a plastic sleeve around the throat of the carb. this sleeve will crack, causing the carb. to come loose.
(CURE) Remove the carb. turn the plastic collar with a pair of pliers 180degs. sand the plastic lightly clean thouroly apply 600deg. J/Bweld to the cracked section let dry overnight. Next day sand the repair down so it just fills the break.
Apply automotive R.T.V. to the rubber o/ring on the carb. insert carb. tighten pinch bolt LIGHTLY this time and have fun!
My o/s heats up during a long run, so I start the motor out rich for the warm up, by the time the race starts the motor should be adjusted about right.
I hope this answers your question.
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