U20 vibration
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U20 vibration
I have a rebuilt U20 with a vibration at 1500 rpm. New motor mounts and vibration damper. Engine runs fine otherwise. Transmission is good new u joints,new axle bearings, new ss exhaust from Jim Tyler. The only thing I still need to replace is 8 blade cooling fan . The Roadster is a 1966 1600 with 1969 U20 engine and drive train.
Please Help
Kilro
Please Help
Kilro
- Linda
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Re: U20 vibration
What does the person who rebuilt the motor have to say?
Were the carbs synced well?
Linda
Were the carbs synced well?
Linda
Sadly-Linda has passed away 2022. She was the 311's den mother and drove the first Rare-Parts ball joint project. RIP.
- bossbob
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Re: U20 vibration
x2 on Linda's comment, was the rotating assembly balanced, drive shaft? Do you feel the vibration in the seat or the steering wheel. I built a 393 motor got it installed with a used trans and had a similar vibration, couldn't figure it out, changed the angle of the trans, rear end, balanced the drive shaft, turned out to be a bad input or output shaft on the trans. New tranny, and vibration was gone.
68 Roadster 1600
70 Boss 302
65 K-Code Fastback
69 Mach 1 393 Stroker 5 spd
63.5 Galaxy Conv. 427 Dual Carb, 4 spd
72 Ranchero
65 GT Coupe
70 Boss 302
65 K-Code Fastback
69 Mach 1 393 Stroker 5 spd
63.5 Galaxy Conv. 427 Dual Carb, 4 spd
72 Ranchero
65 GT Coupe
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Re: U20 vibration
While revving the engine to 1500 RPM's, with the tranny in neutral, is the vibration still there?
- fj20spl311
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Re: U20 vibration
Check to see if the timing is stable. Could be the springs or weights in the distributor or a loose shaft.
Phil
67.5 SRL311-00148 Blue (FJ cruiser VOODOO Blue)
67.5 SPL311 FJ20E teal SDS EFI
69 SRL311 SOLD
19 Raptor SCAB
67.5 SRL311-00148 Blue (FJ cruiser VOODOO Blue)
67.5 SPL311 FJ20E teal SDS EFI
69 SRL311 SOLD
19 Raptor SCAB
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Re: U20 vibration
All good guesses.
Would help to isolate the problem.
As Gar sugvested, is the vibration present in neutral both with clutch engaged and not?
Or, only when moving? All gears or only 1? Specific speed? When vibrating, does it continue with clutch pushed in? What about turning left or right, uphill or down, braking or not?
Lots of causes for vibration, the better you can exactly pinpoint conditions, the better our chance of helping.
Dan
Would help to isolate the problem.
As Gar sugvested, is the vibration present in neutral both with clutch engaged and not?
Or, only when moving? All gears or only 1? Specific speed? When vibrating, does it continue with clutch pushed in? What about turning left or right, uphill or down, braking or not?
Lots of causes for vibration, the better you can exactly pinpoint conditions, the better our chance of helping.
Dan
SPL311 aka Skooter. Sold. Now wasting away in the SF area.
1990 Nissan 300zx. Sold this one too.
2018 VW Tiguan
1990 Nissan 300zx. Sold this one too.
2018 VW Tiguan
- Gregs672000
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Re: U20 vibration
I suspect the fan just based on the rpm... the fan clutch is engaged at that low RPM but would freewheel once the engine reaches a certain RPM, right? I don't know because 1) my car never had one being a 67.5 and 2) I run an electric fan now and have for years. I had a BMW straight 6 have a low rpm vibration that was caused by a broken fan blade... went away as the fan freewheeled.
Greg Burrows
'67 2000 #588
Tacoma, WA
'67 2000 #588
Tacoma, WA
- theunz
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Re: U20 vibration
Easy to check, remove fn belt. If that fixes the problem then it's either the fan, water pump, or alternator.Gregs672000 wrote: ↑Thu Nov 01, 2018 5:02 pm I suspect the fan just based on the rpm... the fan clutch is engaged at that low RPM but would freewheel once the engine reaches a certain RPM, right? I don't know because 1) my car never had one being a 67.5 and 2) I run an electric fan now and have for years. I had a BMW straight 6 have a low rpm vibration that was caused by a broken fan blade... went away as the fan freewheeled.
Mike M
Old enough to know better, too old to remember why!
1969 2000 solex mine since 1972, under resurrection. (Finally resurrected as of spring 2019!)
1969 Porsche 911s -worth more, but not as valuable! Gone!
2017 Lotus Evora 400 - Oh my!!
Old enough to know better, too old to remember why!
1969 2000 solex mine since 1972, under resurrection. (Finally resurrected as of spring 2019!)
1969 Porsche 911s -worth more, but not as valuable! Gone!
2017 Lotus Evora 400 - Oh my!!
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Re: U20 vibration
Thank you for your sugestions. In answer to questions I rebuilt the engine, Vibration is there in gear and neutral,new carbs and synchronized. no clutch on fan just spacer. Will check stability of timing and also run engine without fan belt.
Thank You
Kilro
Thank You
Kilro
- bossbob
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Re: U20 vibration
Any update on your vibration problem?
68 Roadster 1600
70 Boss 302
65 K-Code Fastback
69 Mach 1 393 Stroker 5 spd
63.5 Galaxy Conv. 427 Dual Carb, 4 spd
72 Ranchero
65 GT Coupe
70 Boss 302
65 K-Code Fastback
69 Mach 1 393 Stroker 5 spd
63.5 Galaxy Conv. 427 Dual Carb, 4 spd
72 Ranchero
65 GT Coupe