Another snapped drive shaft and another query or two

Another snapped drive shaft and another query or two

Author
Discussion

scerbera

Original Poster:

102 posts

113 months

Monday 6th April 2015
quotequote all
What a pig!

At least I was only 5 miles from home this time and not 300.

I am going to machine up my own replacements this time. Out of Titanium, stronger and lighter. I can't be doing with this again. I'll put up pics and update when it's done hopefully in around 3/4 weeks.


Also, could someone who has a non leaky car put up a picture of the positioning of the door seals please? Mine were replaced by previous owner but done very badly.

Also, the drivers door has a mind of it's own and has now started to randomly open when i'm driving. It is quite precarious when it happens clearly. Any known faults with this or do i need to take the lock apart?


Many thanks.

pmessling

2,284 posts

202 months

Monday 6th April 2015
quotequote all
What was you doing at the time to snap it

scerbera

Original Poster:

102 posts

113 months

Monday 6th April 2015
quotequote all
I went over a set of speed bumps at 2 mph, then accelerated and bang. Cant have been above 2000 rpm, I think there was no tension on the shaft and it caught but these things are made pretty weak! This will not happen with Ti

a1rak

555 posts

182 months

Monday 6th April 2015
quotequote all
It must have been faulty mine have not failed and it gets pushed on road and track. If you really are going to make a set out of Ti then I would be interested in a set as well pending a price, economy in numbers may be.

jamieduff1981

8,022 posts

139 months

Monday 6th April 2015
quotequote all
Those were dud shafts.

I regularly spin up my wheels. I don't expect the driveshafts to last forever but if you break a shaft pulling away from a speed bump something is far wrong.

I'm not sure titanium is a very good idea.

Byker28i

58,860 posts

216 months

Monday 6th April 2015
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See what Brummie used on his monster rebuild, or a couple of the racers

scerbera

Original Poster:

102 posts

113 months

Monday 6th April 2015
quotequote all
Well Ti is the best shaft material by far so that should be a good choice. I still plan to rebuild the engine and turbo it so future proofing.

I will let you know cost. I have my own machine shop so cost should be ok.

This shaft has only done 2000 miles but i do spin the rears 9 out of 10 starts. It is a 13mile trip to work and i only get 11mpg so fairly heavy use. There are a couple of bumps where you spin at 6000rpm in 3rd which probably dont help but it shouldnt break as my 4.2 is only pushing 320bhp.

Supateg

724 posts

141 months

Monday 6th April 2015
quotequote all
scerbera said:
Well Ti is the best shaft material by far so that should be a good choice. I still plan to rebuild the engine and turbo it so future proofing.

I will let you know cost. I have my own machine shop so cost should be ok.

This shaft has only done 2000 miles but i do spin the rears 9 out of 10 starts. It is a 13mile trip to work and i only get 11mpg so fairly heavy use. There are a couple of bumps where you spin at 6000rpm in 3rd which probably dont help but it shouldnt break as my 4.2 is only pushing 320bhp.
The biggest cost would be the material then, seen as labour is in house!
Let's hope the increased shock loading on the lobro's don't cause them to prematurely fail. Time will tell of course.
Output is about there then, what was the torque like?
Sounds like you enjoying your cerb!


jamieduff1981

8,022 posts

139 months

Monday 6th April 2015
quotequote all
The shafts themselves will be fine but if you drive the way you describe and are destroying steel shafts in 2000 miles then you'll closely be following with the differential, propshaft, gearbox, £1000's worth of clutch and crankshaft...

Your driving style makes mine look sympathetic!

scerbera

Original Poster:

102 posts

113 months

Monday 6th April 2015
quotequote all
I try to be kind to the clutch. Never slip it above 1500rpm ish. Once its engaged properly then i will increase throttle.

Id love to film my daily drive but id get into trouble.

scerbera

Original Poster:

102 posts

113 months

Tuesday 7th April 2015
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Can anyone confirm that both shafts are the same length? The snapped one is 470mm long. Broke on the land for the inner circlip. 96 4.2

Vee8ight

734 posts

138 months

Tuesday 7th April 2015
quotequote all
scerbera said:
Can anyone confirm that both shafts are the same length? The snapped one is 470mm long. Broke on the land for the inner circlip. 96 4.2
they are the same length. the inner circlip groove is the weak spot, they nearly always snap there. the uj's are much much stronger. the new design has a raised bit and not a circlip groove to stop the uj going down the shaft so eliminating the weak spot.

Daz

scerbera

Original Poster:

102 posts

113 months

Tuesday 7th April 2015
quotequote all
Vee8ight said:
scerbera said:
Can anyone confirm that both shafts are the same length? The snapped one is 470mm long. Broke on the land for the inner circlip. 96 4.2
they are the same length. the inner circlip groove is the weak spot, they nearly always snap there. the uj's are much much stronger. the new design has a raised bit and not a circlip groove to stop the uj going down the shaft so eliminating the weak spot.

Daz
Many thanks indeed. I will make something similar.

thefrog

341 posts

218 months

Tuesday 7th April 2015
quotequote all
scerbera said:
This shaft has only done 2000 miles but i do spin the rears 9 out of 10 starts. It is a 13mile trip to work and i only get 11mpg so fairly heavy use. There are a couple of bumps where you spin at 6000rpm in 3rd which probably dont help but it shouldnt break as my 4.2 is only pushing 320bhp.
How do you get the oil up to temp in 13miles ? Your engine will be next ?

macdeb

8,492 posts

254 months

Tuesday 7th April 2015
quotequote all
Vee8ight said:
they are the same length. the inner circlip groove is the weak spot, they nearly always snap there. the uj's are much much stronger. the new design has a raised bit and not a circlip groove to stop the uj going down the shaft so eliminating the weak spot.

Daz
I've had mine made like this without the inner circlip. Brummies are from 'Dave Mac' in Coventry, they did my prop and impressed with service. Brummies previous unbreakable ones broke. The other ones I've seen are the rifle barrel type which are hollow to allow some flex over the length under shock torque, which makes sense. They have no failures apparently but are quite expensive by comparison.
Be interested to hear how the OP and others get on.

scerbera

Original Poster:

102 posts

113 months

Tuesday 7th April 2015
quotequote all
thefrog said:
scerbera said:
This shaft has only done 2000 miles but i do spin the rears 9 out of 10 starts. It is a 13mile trip to work and i only get 11mpg so fairly heavy use. There are a couple of bumps where you spin at 6000rpm in 3rd which probably dont help but it shouldnt break as my 4.2 is only pushing 320bhp.
How do you get the oil up to temp in 13miles ? Your engine will be next ?
The temp of your oil is largely irrelevant. Colder oil will provide a thicker film with a higher resistance to shearing. And so give you higher load carrying. The only real area of concern in a cold engine, and we are only talking very initial startup is that your pistons could expand too quickly for the bore, depending of course on the tolerance. The piston and liner will warm in a few minutes and so with a 30 sec sit on the drive, a 1 min 30 mph limit and get out of the street the engine is warm enough. In my opinion of course.

macdeb

8,492 posts

254 months

Tuesday 7th April 2015
quotequote all
Personally, I like to have heat soak throughout the engine and not just bits of it. Not for one minute saying mines best way but I'm a born worrier.
hippy

Edited by macdeb on Tuesday 7th April 21:50

Andy_mr2sc

1,223 posts

175 months

Tuesday 7th April 2015
quotequote all
scerbera said:
The temp of your oil is largely irrelevant. Colder oil will provide a thicker film with a higher resistance to shearing. And so give you higher load carrying. The only real area of concern in a cold engine, and we are only talking very initial startup is that your pistons could expand too quickly for the bore, depending of course on the tolerance. The piston and liner will warm in a few minutes and so with a 30 sec sit on the drive, a 1 min 30 mph limit and get out of the street the engine is warm enough. In my opinion of course.
That's really novel to hear somebody talking sense about warming engines up.

Edited by Andy_mr2sc on Wednesday 8th April 07:40

pmessling

2,284 posts

202 months

Tuesday 7th April 2015
quotequote all
I noticed the design change when I overhauled my shafts compared to the other ones that I had overhauled before.

Did wonder why the change. But makes much more sense now and good to know I have the better of the two.

scerbera

Original Poster:

102 posts

113 months

Saturday 11th April 2015
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Broken shaft pic.

My materials chap has advised EN26W for the new shafts so that has been ordered. Does any one have a pic of the design without the inner circlip groove? I will make without but thought it would be useful to see before I design my own.

Thanks.