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paul55
Luxembourg
732 Posts |
 Posted - 03/07/2018 : 10:11:56
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| Has anyone got a decent pair of rear N Type springs? I bought a new pair a few years ago, but now that I have come to fit them they look to be about 1/2 too short, not 39" as it says in Blower. |
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Westbury
United Kingdom
2051 Posts |
Posted - 03/07/2018 : 12:22:00
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Paul,
Without trying to sound ‘clever’, have you measured the springs allowing for the ‘bend’ i.e. not in a straight line end to end. It may be that when drawn flat they may be the correct length after all.
Cheers,
Chris |
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paul55
Luxembourg
732 Posts |
Posted - 03/07/2018 : 17:38:31
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As you can see (I hope!) the spring is nearly flat, I have placed wood spacers between under the axle and the chassis. I have tried to measure the main leaf, from the centre of the front bolt to the extreme end in the trunnion, it measures 38.5 inch or close to. The end of the spring is still inside the trunnion bush by 6mm. I would guess that if the spring was flat the end of the spring might just poke out of the trunnion. Is this normal? Can anyone with a N advise?
Thanks,
Paul.
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WimvanSanten
Netherlands
30 Posts |
Posted - 03/07/2018 : 18:29:42
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Hi Paul,
I will measure mine tommorow. I think yours are to short indeed. Mine are 100% within the trunions without the wooden spacers.
Wim
WvS |
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Westbury
United Kingdom
2051 Posts |
Posted - 03/07/2018 : 18:30:35
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Hello, Paul.
I have just checked my N type ( conveniently I haven’t yet fitted my new trunnions covers) . With the car standing on flat ground and with the full weight of the car on the rear springs, the end of the spring is approximately 1/16” short of protruding through the rear of the bronze trunnion itself.
My hunch is that your spring is correct. Did you measure along the main spring leaf with a tape measure following the spring contour from the centre of the spring ‘eye’ to the end of the spring ?
Hope that helps you.
Chris. |
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paul55
Luxembourg
732 Posts |
Posted - 03/07/2018 : 18:59:36
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Thanks Chris, yes I tried to measure the main leaf and it's 38.5 inch or close to. But from what you have seen I think that mine will be the same as yours, just flush or +/- inside or outside of the trunnion. When you just checked your spring is it just about flat, or still slightly curved? Do you have new springs or are they original?
Paul. |
Edited by - paul55 on 03/07/2018 19:01:03 |
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paul55
Luxembourg
732 Posts |
Posted - 03/07/2018 : 19:04:29
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WvS, thanks for taking the time to check your N, but at the moment I don't have the rebound rubbers on the chassis and under the axle. I was trying to replicate these with my wood pieces. And are your springs flat or slightly curved downwards?
Paul. |
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Westbury
United Kingdom
2051 Posts |
Posted - 03/07/2018 : 19:49:41
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Hello, again, Paul.
Just checked my car again. My rear springs have a radius similar to yours, they are nowhere near flat and that is how they should be. I have no idea how old the springs are but they appear to be in good order. I will try later on to measure the length of the main leaves for you if you wish.
Chris. |
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powerplus
United Kingdom
599 Posts |
Posted - 03/07/2018 : 19:52:56
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Paul,
If it is any help, on my N the distance between the end of the spring leaf beneath the main leaf and the outside surface of the chassis tube, whilst the wheel is off the ground, is 1.5 inches, This distance is just sufficient to allow the spring grease rubber to fit on the main leaf without touching the leaf beneath the main leaf.
Powerplus. |
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paul55
Luxembourg
732 Posts |
Posted - 03/07/2018 : 20:08:02
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Thanks Alan, just about worked out what you mean. I'll have a look.
Chris, As a check, how much distance is there between the chassis frame and under the axle, I don't have any bump stop fitted yet to the chassis, that's what I have used the wood for, but if your axle is clear above the chassis bump stop, then I guess that it's higher than my axle making the spring flatter. One other thing, how tall is the chassis bump stop under the axle? Is it easy to measure?
Paul. |
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Westbury
United Kingdom
2051 Posts |
Posted - 03/07/2018 : 23:08:53
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Paul.
I have looked at my car again. The rear axle rubber bump stops on my car are approximately 1” deep. The underside of the axle is almost or just touching the top of the stops.
Hope you are able to sort your problem.
Regards,
Chris. |
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paul55
Luxembourg
732 Posts |
Posted - 04/07/2018 : 08:10:10
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Cheers Chris, my axle is no where near over 1" clear of the chassis, more like 1/2 inch. I'll have to try to get more weight on it to compress the spring, then if I can get it to over 1" clear then see where the spring is inside the trunnion.
Thanks again,
Paul. |
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coracle
United Kingdom
1973 Posts |
Posted - 04/07/2018 : 12:25:31
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1) I don't have an N but;
2) From a pure engineering point of view the spring should extend beyond the trunnion bushes under all circumstances;
3) A good indication is shown in the wear pattern see first picture: http://www.triple-mregister.org/forums/topic.asp?TOPIC_ID=14554 (Not necessarily an N but a good example)
4) If this were not the case then an odd wear pattern inside the trunnions would take place eventually resulting in excessive end to end loading.
5) If Blower says 39" and yours are 38 1/2" and do not protrude beyond the trunnions then they are clearly too short.
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Westbury
United Kingdom
2051 Posts |
Posted - 04/07/2018 : 12:55:56
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Hello Nigel and Paul.
Unfortunately, I cannot accurately measure the length of my main leaves as it is impossible to do so with everything insitu..
Chris. |
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paul55
Luxembourg
732 Posts |
Posted - 04/07/2018 : 19:10:15
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Well it does look like my springs are too short by 1/2 inch, at the moment it's not an issue. Just trying to get everything assembled in time to have the body fitted later this year. Once is back with the new body I will have more time to investigate this, a new main leaf does seem to be the answer though. Will be in contact with Brost Forge in due course.
Thanks to all for the help as usual.
Paul. |
Edited by - paul55 on 04/07/2018 19:12:37 |
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DickMorbey
United Kingdom
3682 Posts |
Posted - 04/09/2018 : 16:41:04
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We are sorry to report that Brost Forge has ceased trading wef 1 September. They say that this is because their landlord is selling the premises although it is reported that this may have followed the imposition of unacceptable controls on their business by 'the authorities'.
Dick Morbey
PA-PB 0743
Frieth, Oxon, UK |
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