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Help with drive train noise
stefjw87 - 17/9/20 at 07:13 PM

Hello everyone.

I'm struggling to identify a strange noise my formula 27 is maki g

It currently has a zzr1400 engine upfront with an English axle at the rear.

Ill try to explain this the best i can. It sounds like a metallic grinding noise on throttle. It only happens when I'm above a certain speed, around 50mph.

At first it will only occur if I'm holding my speed under constant light throttle and if I accelerate more and the noise will go away. As my speed increases the noise will return and it requires greater throttle input to clear it. I also hear it momentarily as I release the throttle. Gear selection or rpm changes don't seem to make a difference but the speed it first occurs seems to be constant.

I originally thought it was coming from the diff but that's just been off to a specialist and had a new crown wheel, pinion and all the bearings replaced so I'm thinking this is less likely now.

The only other things I can think of are the prop shaft at the engine side or the clutch springs ?

If anyone could give me any ideas it'd be very much appreciated.

Thanks

feckn7 - 17/9/20 at 07:48 PM

My guess would be universal joints.

My Blackbird engined car makes a rattling noise light throttle, which goes away under power.
Front universal had some play so replaced that - noise reduced but still there.
Rear universal also has play. It's a staked joint so I have to get that replaced by an engineering shop - not done yet

There's some older threads on here mentioning the same sort of noise and fix.

David

stefjw87 - 17/9/20 at 09:07 PM

quote:
Originally posted by feckn7
My guess would be universal joints.

My Blackbird engined car makes a rattling noise light throttle, which goes away under power.
Front universal had some play so replaced that - noise reduced but still there.
Rear universal also has play. It's a staked joint so I have to get that replaced by an engineering shop - not done yet

There's some older threads on here mentioning the same sort of noise and fix.

David


Thanks for the reply

I tried to do a search but didn't see anything. I'll try searching some more.

I'll have a look at the joints and see if there's anything obvious. Thanks

BenB - 17/9/20 at 09:50 PM

Car makes noise when not on full throttle. Surely that's ya problem?
My Locost makes strange crunchy noises at low throttle or when backing off. Answer is to send it. Your mileage may vary 😀

stefjw87 - 17/9/20 at 10:00 PM

quote:
Originally posted by BenB
Car makes noise when not on full throttle. Surely that's ya problem?
My Locost makes strange crunchy noises at low throttle or when backing off. Answer is to send it. Your mileage may vary 😀


😄 very good.

I'm just wanting to make sure something isn't going to fail at 100mph and try to kill me. The cars already cost me significant amounts of money when I've ignored strange noises in the past. I'm trying to avoid it again if it can be helped

40inches - 17/9/20 at 10:33 PM

My ZX9R MK made the same noise, tried different Diffs, new propshaft and nothing worked, just accepted it
I think there is a sweet spot for the UJ angles. There is a Fornula 27 locally with a ZX9R and it is sweet, but the engine seems very high, so that may be the answer????

stefjw87 - 17/9/20 at 10:42 PM

quote:
Originally posted by 40inches
My ZX9R MK made the same noise, tried different Diffs, new propshaft and nothing worked, just accepted it
I think there is a sweet spot for the UJ angles. There is a Fornula 27 locally with a ZX9R and it is sweet, but the engine seems very high, so that may be the answer????


Thanks for the reply.

My air filter is already poking out the bonnet fairly high. I'm not sure how much higher it could be mounted.

The car never used to make the noise. I'm assuming it isn't the diff since it's just been stripped. I don't think it's anything to do with the engine/gears. I guess I'll just give the propshaft a good look over and if the joints are fine I guess I'll just have live with it

[Edited on 17/9/20 by stefjw87]

[Edited on 17/9/20 by stefjw87]

stefjw87 - 17/9/20 at 10:46 PM

Does anyone know what causes the universal joints to make such a noise ? Should there be obvious play in them ?