Rear coilover upgrade?

Larger 4 cylinder engines, body mods, major brake and handling modifications.

Rear coilover upgrade?

Postby Milts » Wed Nov 09, 2016 12:01 pm

Rear suspension woes.

I have reluctantly removed the rear 1.5" lowering blocks from the rear of my minor :( (really prefer that lowered look)
but the generally bad road surfaces are causing bottoming out on the rear of the car.

However having removed the blocks this doesn't seemed to have improved things. On further inspection the rear leaf springs are pratically flat (these springs were new 2013) the rear spring shackle mounts are almost touching the chassis. see pic

Image

1. Should i fit new better quality springs with the hope of refitting lowering blocks and be done with it? or

2. Could i replace the Gas telescopic dampers currently fitted with rear adjustable coilovers and keep with the existing leaf springs? These dampers are looking quite compressed don't you think? Car is sitting at rest back on the ground in this shot

Image

Image
This spring is relaxed in this shot as body is supported on stands.



Escort mk2 axle is fitted.

I'm assuming the turret conversion done would be man enough to accept a coilover conversion? has anybody done a similar thing?

Thanks in advance Steve.
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Re: Rear coilover upgrade?

Postby MartinB » Wed Nov 09, 2016 12:43 pm

Not sure if you will get a spring in that turret, it needs to clear throughout the suspension travel, most after market spings are 2 1/4" ID or the smaller ones are 1.9" ID but then you also need the correct dampers for the springs.

How does the turret attach to the chassis (I know it is welded in but is it welded to the chassis rail or just the floor pan)? I don't think the lower mount is ideal for coil overs either.

Are you looking to 5 link or just add extra springing? Another alternative is to add leaves to your current springs.

Also, what bump stops are you using?
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Re: Rear coilover upgrade?

Postby chrisryder » Wed Nov 09, 2016 12:54 pm

It'd be worth changing to the 7 leaf springs at least. They're stiffer, and don't seem to sag as much as the 5's.
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Re: Rear coilover upgrade?

Postby Milts » Wed Nov 09, 2016 2:17 pm

MartinB wrote:Not sure if you will get a spring in that turret, it needs to clear throughout the suspension travel, most after market spings are 2 1/4" ID or the smaller ones are 1.9" ID but then you also need the correct dampers for the springs.

How does the turret attach to the chassis (I know it is welded in but is it welded to the chassis rail or just the floor pan)? I don't think the lower mount is ideal for coil overs either.

Are you looking to 5 link or just add extra springing? Another alternative is to add leaves to your current springs.

Also, what bump stops are you using?



Appreciate your quick replies guys.


I would be looking at the 1.9" ID units i guess. If it's do able with relation to space and lower mount, i hope a supplier would advise with ideal size/poundage.

I can only show you some more photos of the turret mounts, not sure if these will help with regard to their strength and suitability as to how they were welded in? (Just to note, a metal firewall had also been welded in)

Image

Image


Standard bump stops retained albeit cut down
I'm not planning to go to a 5 link setup, It's only used for road use with' occasional' spirited driving :oops: . Just would like car to be useable and sit lower.


With regard to fitting a 7 leaf spring that could be an option too, although i've heard it say 'best to keep the rear end as soft as poss' ?? but i guess you can't have it both ways :?

I understand Rossendale? are the guys to use should i need to plump for replacement leaf springs.



Thanks again for your advice
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Re: Rear coilover upgrade?

Postby MartinB » Wed Nov 09, 2016 2:59 pm

If you are going coil over, you need to measure up what you need and don't expect a supplier to be able to tell you what springs you need (unless from JLH obviously) especially if you are using the leaf springs as well.

When I fitted coil overs on the rear of mine many years ago, I placed the coilover directly on top of the axle case to stop any unwanted twist on the axle due to the loads going through it, if you have a four/five link you can go away from this a bit as the links will stop the twist (but then you get into leverage ratios for the spring rate), if you only have anti-tramp bars I think it will still twist slightly.

I have run from 50 lb/in springs right up to 300 lb/in springs on the rear of mine, the 50s gave more travel but needed more preload to support the weight of the car, 300s a lot less travel and very little preload.

Unless you buy a ready made kit you will always have to work it out for your individual application unfortunately depending upon what you are using it for and whether it will be heavily laden at all.

Mine has the bumpstops on the coilovers and with the five link I can get it so the axle tubes will touch the boot floor with the diff nicely in the hump.

I think easiest way for you is 7 leaf springs and put the lowering blocks back in.
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Re: Rear coilover upgrade?

Postby Custard » Wed Nov 09, 2016 10:43 pm

The dampers would have had more travel, for the same axle travel if they were mounted to the rear of the axle.

Also as long as you were willing to sacrifice boot space the turrets could have been taller.

It looks like they were located in front to retain boot space and short to allow a rear seat.

Sean.
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Re: Rear coilover upgrade?

Postby Milts » Wed Nov 09, 2016 11:31 pm

Custard wrote:The dampers would have had more travel, for the same axle travel if they were mounted to the rear of the axle.

Also as long as you were willing to sacrifice boot space the turrets could have been taller.

It looks like they were located in front to retain boot space and short to allow a rear seat.

Sean.


Hi Sean
Thanks for your observation and accept things could of been done differently, but i have to work with what has been done, unfortunately i do not have the budget to make major chassis changes.

You are bang on with regards to limited boot space, with a repositioned fuel tank in there, and yes it does allow for a rear seat. not that you could use it with the roll cage there :blackeye:
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Re: Rear coilover upgrade?

Postby jonathon H » Thu Nov 10, 2016 12:07 am

All leaf springs for UK Minor suppliers are second rate, We use Rossendale springs , which are tempered correctly and do not loose their spring rate. Not cheap but they are quality items. We often now specify low spring rate leaf springs and add in a coil over unit as you suggest. This gives the ability to alter the rear spring rate, set up corner weights a tad more accurately, and the ability to alter ride height. Do not fit 7 leaf springs as the car will 'hop', you want the rear soft, not enough to roll but give good grip. Here are some examples
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Re: Rear coilover upgrade?

Postby Custard » Thu Nov 10, 2016 10:15 am

Depending on your access to welding and how much room the tank does actually take it could be cheaper to modify the turrets.

Looking at the lower brackets if they were swopped from side to side they would point rearwards.

Or if you definitely did not want a rear seat longer ones could be fitted in the current position.

Either way the cost would be the steel and welding vs springs and dampers. Looked like you were on GAZ ones and they weren't cheap on my kit car.

Admittedly if you are not doing it yourself or on mates rates the cost may not be too dissimilar and springs and damper change would be a bolt on bolt off job, but if you want the adjustability of coil overs you may still need to modify the turrets to clear the springs.

Our roads are more like a rally course than an F1 track so what you are usually after is reasonable travel but in a well controlled manner.

If you do go the change damper route ideally you could do with supporting the body, removing the spring and damper and then jacking the axle up and down a bit to work out what the closed length and open length needs to be. And if you go for coil overs you are guessing how much weight the leaf springs take and how much the coil takes. You often get it wrong the first time, or want to change as you drive quicker.

It is all part of having a non standard car, enjoy making the changes and seeing the results, it is addictive and the car is never finished.

Sean.
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Re: Rear coilover upgrade?

Postby austin » Thu Nov 10, 2016 11:12 am

If the only problem in the first place was 'bottoming out' the cheap and simple solution might be longer spring shackles. This avoids stiffening the overall spring rate, but gives a bit more clearance over bumps. It seems a bodge I know, but might give you what you want.
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Re: Rear coilover upgrade?

Postby Milts » Sat Nov 12, 2016 1:10 pm

Looks like a set of leaf springs are on the cards for starters.
Visited the classic car show on Friday spoke with a Spax rep about CSX coilovers - can be built to a customers' spec, this might be an option??
Will get in touch with JLH next week.

Thanks for all your suggestions and ideas, i hope to update this thread with a positive outcome :)


BTW, i found another blinding photo of MB's car on the net the other day and will add it in the 'Gallery (Modified) Section' for good measure, i hope he doesn't mind! One of my favourite looking Minors :raz: :raz: :raz: Gives me inspiration :D
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Re: Rear coilover upgrade?

Postby Islipminor2 » Sun Nov 13, 2016 6:17 pm

We went the more 'simple' route 40+ years ago!

Being a 1958 car, we started out with 7-leaf springs (car not Traveller), and when we fitted 'wide wheels and radial ply tyres' back in 1970, I lowered the car all round by ~2". At the back I took the shortest, bottom leaf off, turned it upside down and refitted on top of the long top leaf. The effect is to flatten the spring slightly and soften it at the same time, so yes, best of both worlds - lower and softer. That was >100,000 miles ago and they are still working well.

For dampers we originally had some telescopic of now unknown origin, that were replaced with Koni adjustables 18 years ago. They are fitted at a slight angle up to a crossmember mounted across the floor pan, and also work very well, but if you do go this route, make sure that you use some large diameter (>=50mm) 3mm thick washers inside the boot area to spread the load, otherwise the boot floor will develop some splits over time - yes it did, after ~50,000 miles.

Where the Konis at the front are on 'full hard', those at the back are set to 'full soft'. The ride is very well damped, firm, but definitely not harsh, even with polyurethane bushes fitted everywhere on the suspension mounts.

The bump stops have been shortened by ~1", and reprofiled. The axle rides with around 1.5" clearance to the bump stop, unladen.

At the rear of the springs, the shackles do get quite close to the return edge of the inner wing, and this needs to be trimmed to give clearance. The spring eye never gets near the chassis leg itself, only the return edge.
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IMG_1627a.jpg
Picture showing the revised 7-leaf spring, bump stop shape and Koni damper
IMG_1628a.jpg
Return edge relieved to give clearance to the spring eye
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