Horrendous transmission noises in a selection of Caterham's

Horrendous transmission noises in a selection of Caterham's

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Roblot

Original Poster:

36 posts

78 months

Wednesday 27th September 2017
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Thanks to all for a stimulating discussion.
My cars did not have LSD as I was told that they tended to be more noisy especially for the road. I have to agree that on the track noise generally is not a consideration, handling and lap times are the key issues, however when the cars need to be used on congested roads then excessive transmission noise
( engine and induction noises sound great) can be tiring after a while.
I have been told that the older cars are quieter with regard to diff and gearbox noise and I think many of you agree, maybe one day I will try again, at the present I am driving a supercharged Lotus Elise, and although it does not have the Seven's ability is at least quiet!

bcr5784

7,102 posts

144 months

Thursday 28th September 2017
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Roblot said:
Tom,

I think that's great you have solved the problem, must be great to be able to make good progress with a quiet transmission.
If the problem is as common as it appears to be, instead of dealers saying ',they all do that sir' why don't they apply Toms's fix to the cars, it would help a lot of drivers suffering with the problem, ( some owners might not have the technical knowledge that Tom has.) I know some say that the noises are part of the experience but not for everyone!
Agree. Everyone expects a Caterham to be raw, but the transmission noise turns raw into crude for me. Given that problem has been ongoing for years and clearly some (including me) are put off buying a new one as a result, it astonishes me that Caterham haven't made a serious attempt to address the problem.

anonymous-user

53 months

Saturday 20th June 2020
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Resurrecting this thread in case anyone’s interested.

My R400’s diff (car built 2015, 8000 miles now) had always chattered as you gently lifted off the throttle. A highish pitched chatter that was not there under power, not there if you lifted off altogether, just when you lifted off a little. Learned to live with it, easy to avoid, no real issue.

About a month ago the chatter suddenly became very loud on lift off, same noise but noticeably louder. Diff out, off for a full rebuild (at only 8000 miles, quality eh?). I mean full rebuild. All new sintered LSD plates and washers, all new bearings and seals etc. Carbon plates and Belleville’s broken up.

All back together and the noise is still there, louder than it originally was but now, not when you gently lift off but when you take your foot off altogether, though it lessens when you brake. Harder to avoid lifting off altogether than just lightly, so harder to live with though it’s early days yet.

Can’t say I’m at all impressed by the efforts of CC and Titan if this is the best they can do.






Roblot

Original Poster:

36 posts

78 months

Sunday 21st June 2020
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I do have sympathy with those owners of sevens with noisy transmission. Which in fact made me give up
Many suffer in (silence!) or try to block out the noise with head sets etc.
There are a few lucky owners, usually in older generation cars where there does not seem to be a problem. I know it makes little difference on a track where performance is the key issue, however for those who want cruising and or fast road use it can completely spoil the drive. Many make excuses that it is part of the character and that you are sitting next to the diff and gear box but it seems especially to be a problem in sevens (although my previous twin cams with live rear axle were ok). The exhaust noise or the induction noise from roller barrels or carburettor trumpets are great sounds IMO and are not part of the problem. In this day and age it should be possible to produce diffs and gear boxes that don't wine and chatter,furthermore some of these noises which we accept in sevens would not be tolerated in other cars.
I wish you all the best in your quest for quieter transmission.

anonymous-user

53 months

Sunday 21st June 2020
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I think you’re right.

What most annoys me at the moment is that where before the rebuild the chatter, which I believe is CW&P, was not so loud and only happened in a partial lifting. It was easy to avoid.

Now, after rebuild, its louder and happens under engine braking and generally slowing down, unless actually braking so is much harder to avoid.

Indefensibly poor engineering IMO.


DCL

1,215 posts

178 months

Sunday 21st June 2020
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I think you've fallen in the trap of thinking a rebuild will be like new. I did quite a bit of research when Caterham started to use remanufactured differentials and noise suddenly became a big issue for them.

Ford used an incredible amount of their resources to make the Sierra diff quite - even to the point of creating unique gear profiles and limiting production to a few specialist plants. The profile of the crown wheel and pinion was by no means 'standard gearing' and the contact patch was manipulated with a set of factory jigs and tools - all aimed at reducing noise.

So it should be no surprise that when you fit an aftermarket crown wheel an pinion designed as a robust motorsport application that the full resources of 1970's Ford development isn't there. It is easy to make a strong diff, but very difficult to make it strong and quiet.

Edit: just re-read your post and you probably have a BMW diff, but the same basic principle apply to BMW, or factory built, and overhauled diffs.


Edited by DCL on Sunday 21st June 14:38

anonymous-user

53 months

Sunday 21st June 2020
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Yes, it’s the BMW diff.

I get all that, and don’t expect saloon car quiet but the chatter is now much worse than it was before being rebuilt.

I can’t see why that should be inevitable, if reassembled carefully to the right settings.

Also, as far as I know, this was all new 8k miles ago, not aftermarket. Unless CC are buying up used BMW diffs and reworking them. Which wouldn’t surprise me actually.

Edited by anonymous-user on Sunday 21st June 16:02

nigelpugh7

5,997 posts

189 months

Monday 22nd June 2020
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The only thing I can say in reality, after owning 7 different models of Caterham’s in the last 22 years, is they actual do what the dealer says, in that yes they all do that sir.

I have had Supersport, R400, R500, 620R ,models with 5 speed, 6 Speed, Quaife 6 Speed Sequential , Sadev Six Speed Sequential, Ford diffs with and without LSD, and pretty much all of them have had backlash and transmission noises.

Perhaps the best one, from having the least amount of noise was my last R500 Duratec, with the Caterham six speed, and the BMW diff with LSD.

As has been mentioned re the diff mounts, it’s the close proximity of the diff and it’s mounts the the left ear of the driver,,that makes you hear so much of the mechanical noise of the driveline.

It’s also the rigidity of the diff bushes in to the mounts, that contributes to NVH through mechanical connections from diff to chassis.

I am also aware that a lot of the noise comes from the transmitted NVH produced in the gearbox and amplified by the harshness of the diff mounting again close to the driver.

So no matter what you do, eliminating completely is impossible, it’s just managing the day to day life and use the best way you can.

My current 620R is noisy on transmission because of the diff and mounting, but also because of the Sadev 6 Speed sequential, but I wouldn’t change it for the world, the pure unbridled joy from full throttle flat shifts on the way up has to be experienced to be believed.

And yes good quality ear plugs are a great help, but I don’t wesr them all the time.

anonymous-user

53 months

Monday 22nd June 2020
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nigelpugh7 said:
The only thing I can say in reality, after owning 7 different models of Caterham’s in the last 22 years, is they actual do what the dealer says, in that yes they all do that sir.

I have had Supersport, R400, R500, 620R ,models with 5 speed, 6 Speed, Quaife 6 Speed Sequential , Sadev Six Speed Sequential, Ford diffs with and without LSD, and pretty much all of them have had backlash and transmission noises.

Perhaps the best one, from having the least amount of noise was my last R500 Duratec, with the Caterham six speed, and the BMW diff with LSD.

As has been mentioned re the diff mounts, it’s the close proximity of the diff and it’s mounts the the left ear of the driver,,that makes you hear so much of the mechanical noise of the driveline.

It’s also the rigidity of the diff bushes in to the mounts, that contributes to NVH through mechanical connections from diff to chassis.

I am also aware that a lot of the noise comes from the transmitted NVH produced in the gearbox and amplified by the harshness of the diff mounting again close to the driver.

So no matter what you do, eliminating completely is impossible, it’s just managing the day to day life and use the best way you can.

My current 620R is noisy on transmission because of the diff and mounting, but also because of the Sadev 6 Speed sequential, but I wouldn’t change it for the world, the pure unbridled joy from full throttle flat shifts on the way up has to be experienced to be believed.

And yes good quality ear plugs are a great help, but I don’t wesr them all the time.
Thanks Nigel. Generally I understand all that it’s just that the latest noise is louder and occurs differently to how it was before the rebuild.

If you copy and paste this link, you can hear the noise. I’d appreciate your opinion.

https://www.dropbox.com/sh/7xjo8hlsehrqpvb/AACr0K1...

And this

https://www.dropbox.com/s/348zbzd3dahifou/34%20Mar...

The first one is accelerating up to 60 or so and lifting off. The second a low speed.

BertBert

18,955 posts

210 months

Monday 22nd June 2020
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So I was thinking how horrendous can it be? That's a pretty horrible sound!

ghibbett

1,900 posts

184 months

Monday 22nd June 2020
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Blimey, and there's me thinking the diff in my 420R was worse that my Supersport (which it is).

But it's no where near as 'chattery' as that!

Watchman

6,391 posts

244 months

Monday 22nd June 2020
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Whilst touring Ireland in 1999 with a group of other Se7eners, I pulled up to a junction then panicked a little because of an extreme whining and crunching sound. Took me a few seconds to believe that the noise was coming from the straight-cut box in the Se7en behind me (and not my own car). Turned out, he was happy wiith it "working as intended" but I struggled to understand how anyone could live with that.

braddo

10,399 posts

187 months

Monday 22nd June 2020
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Blimey. I have a late 90s k series with 6 speed box and a lsd, and there is nothing like this sound. I live in London so there is plenty of gentle town driving too.

Is a lightened flywheel a factor with the backlash? I hired a brand new 270r last year and a light flywheel certainly made smooth slow driving harder.

ETA there is a small amount of whine and in my car, and a small amount of driveline slack like an old car’s, but I find it very minor and not remotely hard on the ears. YouTube videos of Caterhams certainly don’t suggest to me that “they all do that”...

Edited by braddo on Monday 22 June 22:01

anonymous-user

53 months

Tuesday 23rd June 2020
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Thanks for listening guys.

Just to clarify, it was nothing like this until it was rebuilt recently. There was just a much milder chatter, only on partial lift off, that was easy to avoid.

Following a discussion on the BC forum, I’m going to check the angle of the diff. It’s been suggested that this stems from the fact that the Duratec is canted forward 1.5 degrees and the diff should be too. (it’s important that the UJs are parallel).

It might be that I’ve put the diff back at a slightly different angle and that could be causing this. That could do it but I have two reservations:

Firstly, I don’t think there’s enough movement in any of the bolts to allow for a significant difference.

Secondly, I can find no evidence that CC locate the diff any differently for a Duratec than they do for a Sigma, which isn’t tilted. Of course, in that may lie a clue to other noises.

Any comments or thoughts on this would be appreciated.

By the way, the sound files were simply
made with an iPhone lying on a coat on the passenger seat, they don’t do the noise justice!

Edited by anonymous-user on Tuesday 23 June 08:04

nigelpugh7

5,997 posts

189 months

Tuesday 23rd June 2020
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REALIST123 said:
Thanks Nigel. Generally I understand all that it’s just that the latest noise is louder and occurs differently to how it was before the rebuild.

If you copy and paste this link, you can hear the noise. I’d appreciate your opinion.

https://www.dropbox.com/sh/7xjo8hlsehrqpvb/AACr0K1...

And this

https://www.dropbox.com/s/348zbzd3dahifou/34%20Mar...

The first one is accelerating up to 60 or so and lifting off. The second a low speed.
Good god that really is bad!

The nosiest I have ever had was my white R500 Duratec with the Quaiffe sequential box, and I know most of the noise came from the gearbox.

But that noise on your car is something different all together.

My suggestion would be to get it to a garage with a good four post lift that will allow it to be run with the wheels off the ground whilst underneath it to work out where it’s actually coming from.

And if I was to have an educated guess from that noise, I would say it’s mostly likely the bearing on the front of the diff by the prop that’s causing the noise you have, could even be the UJ at the diff end of the prop as well.

anonymous-user

53 months

Tuesday 23rd June 2020
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nigelpugh7 said:
REALIST123 said:
Thanks Nigel. Generally I understand all that it’s just that the latest noise is louder and occurs differently to how it was before the rebuild.

If you copy and paste this link, you can hear the noise. I’d appreciate your opinion.

https://www.dropbox.com/sh/7xjo8hlsehrqpvb/AACr0K1...

And this

https://www.dropbox.com/s/348zbzd3dahifou/34%20Mar...

The first one is accelerating up to 60 or so and lifting off. The second a low speed.
Good god that really is bad!

The nosiest I have ever had was my white R500 Duratec with the Quaiffe sequential box, and I know most of the noise came from the gearbox.

But that noise on your car is something different all together.

My suggestion would be to get it to a garage with a good four post lift that will allow it to be run with the wheels off the ground whilst underneath it to work out where it’s actually coming from.

And if I was to have an educated guess from that noise, I would say it’s mostly likely the bearing on the front of the diff by the prop that’s causing the noise you have, could even be the UJ at the diff end of the prop as well.
Thank you.

Problem with your idea is that I don’t think it’ll do it without some engine braking load which might be hard to replicate on a lift and I wouldn’t fancy doing that with the suspension in full droop either.

Bear in mind that the chattering has always been there, as I said earlier. It’s just far, far worse following the rebuild,
which included all new bearings.


BertBert

18,955 posts

210 months

Tuesday 23rd June 2020
quotequote all
That's very interesting about the pinion angle, not had cause to think about it before. A quick couple of videos on youtube make for interesting watching.

I suppose it could well cause a loading and unloading effect on the cwp especially under light loads and possibly at the frequency you are hearing.

It's never come up in (my) Caterham builds before as there is nothing to adjust with regard to the fitment of the engine/box and diff.

Be interesting to see how you get on. Your thread on BC is interesting.

Bert

nigelpugh7

5,997 posts

189 months

Tuesday 23rd June 2020
quotequote all
REALIST123 said:
Thank you.

Problem with your idea is that I don’t think it’ll do it without some engine braking load which might be hard to replicate on a lift and I wouldn’t fancy doing that with the suspension in full droop either.

Bear in mind that the chattering has always been there, as I said earlier. It’s just far, far worse following the rebuild,
which included all new bearings.
Yep a fair point, would it work on a rolling road?

I wonder what the original source of the chattering is.

Can’t recall, did you build it, or was it a factory build?

I would also take it to and independent specialist. Depending on which one is closer to you, I have used McMillan motorsport in Hinckley they are very good at Caterham car setups.



anonymous-user

53 months

Tuesday 23rd June 2020
quotequote all
BertBert said:
That's very interesting about the pinion angle, not had cause to think about it before. A quick couple of videos on youtube make for interesting watching.

I suppose it could well cause a loading and unloading effect on the cwp especially under light loads and possibly at the frequency you are hearing.

It's never come up in (my) Caterham builds before as there is nothing to adjust with regard to the fitment of the engine/box and diff.

Be interesting to see how you get on. Your thread on BC is interesting.

Bert
Yes Bert, it is interesting, though I’m not sure how significant 1.5 degrees would be. Also, I can find no official reference to the engine being inclined and the diff fitment is the same as the Sigma which, by all accounts, isn’t canted.

I will check the alignment. The idea is that the diff flange should be perpendicular to the gearbox output shaft. That should be in line with the engine block etc and I know the machined flats on the bottom of the diff are perpendicular to the flange so I will check that they and the engine lie at the same angle, with an inclinometer I have.

An angled UJ varies in speed as it turns one rev and if the ends aren’t at the same angle, wear and noise result.

Edited by anonymous-user on Tuesday 23 June 13:52

anonymous-user

53 months

Tuesday 23rd June 2020
quotequote all
nigelpugh7 said:
REALIST123 said:
Thank you.

Problem with your idea is that I don’t think it’ll do it without some engine braking load which might be hard to replicate on a lift and I wouldn’t fancy doing that with the suspension in full droop either.

Bear in mind that the chattering has always been there, as I said earlier. It’s just far, far worse following the rebuild,
which included all new bearings.
Yep a fair point, would it work on a rolling road?

I wonder what the original source of the chattering is.

Can’t recall, did you build it, or was it a factory build?

I would also take it to and independent specialist. Depending on which one is closer to you, I have used McMillan motorsport in Hinckley they are very good at Caterham car setups.
I built the car myself in 2015, Nigel.

I have Luke Stevens about 45 minutes away and will take the car to Luke if I can’t sort it out. He’s done stuff before and is very good IMO and has a rolling road.

I’ve sent him the sound file for his opinion.

Edited by anonymous-user on Tuesday 23 June 14:01