coilover conversion

Rebuilding, adjusting, maintaining & alternatives

coilover conversion

Postby bl0que » Sun Jun 26, 2016 9:26 am

Hi guys,

I am looking to convert my minor front suspension to coilover suspension and I have seen the kit that you can buy from jlh restorations but I want to use the original wishbone modified for the job.
I was wondering if anyone knew much about suspension and what lengths I need as I am yet to check the suspension travel on my minor. I want the same mounting type as the jlh one so just two eyes so to speak. I can't get any info out of avo because they say it is a special they make for jlh and jlh havent got back to me.
I have included the link to the page just incase you haven't seen them :)

http://www.jlhmorrisminors.co.uk/coil-over-kit.html


any suggestions?
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Re: coilover conversion

Postby Custard » Sun Jun 26, 2016 1:24 pm

Lengths will vary depending on the location of the top mount and that is only the start, it is one thing doing a telescopic conversion, once you add in coil overs you are into spring rates and spring lengths as well. And they are affected by vehicle weight (and the angle they are on) so different engines alter what is ideal.

Having done other things from scratch myself I know a lot if it is careful research and even then you do something and redo it a few more times until it is right.

A lot of thought, and man hours of development and refinement goes into a kit like that.

To be honest on a standard engine car I would not have thought it worth the effort, (just get his adjustable telescopic conversion) and on a powerful one it wants to be a well thought out conversion.

Sean.
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Re: coilover conversion

Postby bmcecosse » Sun Jun 26, 2016 6:51 pm

Big mistake - the Minor torsion bar suspension is excellent! It's even adjustable for height - and you can (and should) upgrade the dampers by simply draining and filling with SAE 40 oil. A coil spring is just a rolled up torsion bar anyway! And Issigonis has very cleverly arranged for the torsion bar forces to be taken in the middle of the car - in the cross member. The front panels etc are not designed to take these forces. Save your money - and buy a pint of SAE40 oil..... F1 cars all copied the Minor by using torsion bars - there's absolutely no advantage going to coil springs.....unless you have fitted a much heavier engine - in which case i would ADD them to the T bars - not replace the T bars. Then the new 'helper' springs don't have to carry the heavy loading which the panels are not designed to take.
 









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Re: coilover conversion

Postby bl0que » Sun Jun 26, 2016 9:32 pm

Well i will be putting an mx5 engine in the car in a couple of years and i thought maybe the coilovers would be more convinient. I have heard the original suspension is good enough and i know that the torsion bar system is just the same really i just want the car to go round corners as well as possible when it has the new engine. I am already having to do extensive repairs to the chassis rail anyway so i thought why not do it now?

On the topic of choosing the correct coilover for the job how would i start to go about it? I mean weight can be figured out but spring rates and lengths im not so sure about :p is there any setups you can suggest that i can use for mocking up? When people build their own kit cars do they have a rough estimate they make?
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Re: coilover conversion

Postby MartinB » Sun Jun 26, 2016 9:51 pm

Back in the late 1980s/early 1990s when I first installed the Fiat engine in my Minor I installed coil over dampers in conjunction with the torsion bars.

I used standard Minor torsion bars with 400 ib/inch springs on the coil over shocks, the different frequencies of the springs meant I could run the shocks fairly soft so although the springing was firm it still soaked up the bumps reasonably well and spreads the loads out throughout the car better.

It is worth doing if you are putting a heavier engine in, the standard torsion bars will not be adequate.

However as has been said previously you will need to establish the ride height you want, the location of the inboard and out board mounts, length of damper etc and this is really down to your individual car. Additionally, the lower damper mount should be as near the king pin as possible for maximum effectiveness, the last incarnation of the Minor suspension on my car had the lower damper mount on the 'Y' of the lower suspension arms where they bolt onto the lower trunnion.
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Re: coilover conversion

Postby bl0que » Mon Jun 27, 2016 1:31 pm

I know where I will be mounting my bracket for the top of the coilover, I will be using the existing damper mount and building a bracket off of that.

what do you mean by inboard and outboard mounts?

the length of the damper depends on what I do with the mounts does it not?

thank for help btw :)
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Re: coilover conversion

Postby Custard » Mon Jun 27, 2016 8:45 pm

I think he meant the inboard and outboard ends of your bottom wishbone.

The further out the bottom mount is the more travel it needs. If it was fastened half way along it would only move half as far as the end does. But the spring would have to be twice as strong.

Travel is as you say dependent on the two mounting points, but if it is too extended then there would be insufficient droop when that wheel goes light, and if too compressed, it would not compress much more before the piston bottoms out and you actually get less travel than you expected.

Also the more slanted they are the stronger the spring rate has to be. If I remember correctly my locost kit car (Caterham Style) weighed 450kg Had 200lb springs on the rear which were vertical (and felt a bit hard) and 300lb fronts which were at a 45 degree angle and were reasonably supple.

Unless you have the time and money and enjoy playing with some of this it can work out cheaper to bite the bullet buy a proven kit and spend your time working on the engine conversion.

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Re: coilover conversion

Postby MartinB » Tue Jun 28, 2016 7:49 am

I meant outboard mount for the damper (the one on the wishbone) and inboard mount of the damper(the one on the inner wing), sorry for any confusion.

For most effectiveness the damper needs to 'see' as much of the wheel travel as possible and therefore the lower mount should be as near the king pin as possible. I tried two locations, the initial one had the damper mount directly above the tie bar mount on the lower wishbone and was ok, however, on the final incarnation of Minor suspension on mine I moved the damper mount nearer the king pin (I can't remember the amount but it was 1/2 " or so) and it made a noticable improvement. Also, due to the layout of the inner wing and lower wishbone you will never be able to get to the stage where the damper is at too much of an angle so don't get too caught up in thinking it must be vertical, if you do that you will loose the damper travel in relation to wheel travel and therefore make it less effective.

I developed mine over a period of years for hillclimbs and sprints but was road legal. There will be some on here that will say 'yes but that was for competition but that is too stiff for the road', however while it was stiff, it made the car hugely competant on the road. Also hillclimb cars are generally much softer than circuit race cars as hillclimbs are not as smooth as most circuits.

At the end of the day it depends upon what you want it to be as how the car is set up.
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Re: coilover conversion

Postby jonathon H » Tue Jun 28, 2016 7:49 pm

Err, yes I did email you saying I couldn't help you as I was not aware of the dimensions and design of your kit. Check your emails :D
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Re: coilover conversion

Postby jonathon H » Tue Jun 28, 2016 8:08 pm

Difficult to understand your comment Roy as its clearly not made from a point of experience. The difference between a std set up or a re oiled std system is night and day. Our kit was designed for control and multi adjustment of the cars geometry. Would have been even better with a double wishbone as we have now designed for the MG Midget, but cost and usable anchorage points meant it had to keep the design it has now. The kit is excellent on both road and track and is probably more suited to uprated engines , but nothing to do with engine weight. On track not much lives with my race car in the corners except for Caterhams which run rings around most cars. For a 58 year old car using the original chassis only with our upgrades it still amazes me how good this car handles.
My view is on important areas such as suspension and brakes, if you don't know what you are doing, don't do it.
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Re: coilover conversion

Postby Rocinante » Fri Jul 01, 2016 8:48 pm

Couldn't resist a comment on the subject of modified suspension.
Recently had Stage 1 suspension fitted to the front and rear of my Trafalgar blue 1968 Minor two door saloon by JLH and it is excellent as were JLH from start to finish. Radius arms fitted to the rear. No anti roll bar at the front as recommended by Jonathon. The car corners as if it were on rails and is now a delight to drive.
Fit it and forget it unless of course you want to select one of the twelve settings on the vertical shock absorbers for more exacting needs. :D :D :D :D :?
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Re: coilover conversion

Postby bmcecosse » Sun Jul 03, 2016 9:42 am

Jono - I fully understand from a track/competition point of view. At the beginning this was just a standard car - now it appears it will have a heavier engine, I agree it will benefit from additional coil springs and additional dampers. And of course - adjustability for camber/caster etc will be extremely useful. But way over the top for a standard car. Some of the 'bolt on' suspension 'upgrades' are poor quality and just a waste of money - and can be easily equalled with a pint of SAE40. Properly engineered 'weld on' conversions are of course a very different matter - as I'm sure your kits are Jono. I still believe Minor front end handling would be much improved if the top arm could be mounted lower down and inboard. As it stands now the suspension induces +ve camber at that wheel on bump/roll which can surely never be a good thing.......
 









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Re: coilover conversion

Postby MartinB » Sun Jul 03, 2016 2:45 pm

If you lower the suspension enough the geometry goes past adding positive camber and starts adding negative camber the lower it goes and in roll. However the roll centre plummets making the use of an anti roll bar more of a necessity, just my opinion of course though.
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Re: coilover conversion

Postby haydng » Tue Aug 30, 2016 6:21 am

For what its worth I have done much investigation about potential suspension upgrades for a Traveller I am modifying as a daily driver for my wife.
As a background, the car will be doing long commutes as well as keeping up with highway traffic through the city.
We have access to some revvy little Datsun/Nissan engines here in Oz (120bhp) with 5 speed gearboxes, both of which have bolted into the Morrie without much effort (Datsun originally based the engine on the A-series and is the conversion of choice over here and can be easily reversed) and this combination provides good power and reliability for the driving conditions she will be experiencing.
For this powertrain combination it became very clear that the JLH kit would be the safest and most reliable option with all the worst case scenarios in mind. Coupled with the fact it has been available for some years now, and is consequently well sorted in both road and race track conditions, it was a no-brainer for us.
We were happy to ultimately pay twice the price for it (i.e: when you include the exorbitant cost to freight it to Australia) and satisfied that it remains a high value option due to the inherent quality of the item as well as the excellent service JLH provides. Suffice it to say we remain jealous of UK Morris owners who have access to the JLH units at half the price we paid!
Incidentally, our upgrades include the coil-over front suspension, and turreted rear suspension with radius arms and panhard rod including AVO shock absorbers all round.
Warm Regards to all
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