Boing Boing

[Jonathan Pounsett]

Who’s the spring expert in the club?

Whilst adjusting the tracking I noticed the last 3 coils on the front springs were bottomed out!

Are these springs upside down or are they simply overloaded?

 

[hoobby]

Not a spring expert but I believe that is upside down definitely if progressive

 I have also been told to fit tighter coiled end at top this will help prevent debris getting in-between the windings

 

[mantasrme]

Whichever way up you fit them they will still look the same in regards the amount of coilbound coils.

But its not overloaded its a lowering spring that has been designed/made badly (in my opinion). You basically only have 3 coils that are allowing you movement. For those 3 coils to to take the weight of that corner of the car the actual coil needs to be much stronger. So you get very little movement for a bump and normally a harsh ride on anything thats not smooth road.

Much better to have no coils bound up and the same effective spring rate at the wheel. So when you hit a bump all 6/7 of the coils can move a little for the same wheel movement which gives a more compliant ride.

[mepbowles]

I guess the logical follow up to this is are there any lowering springs that people can recommend?

[Jonathan Pounsett]

1 hour ago, mantasrme said:

Whichever way up you fit them they will still look the same in regards the amount of coilbound coils.

But its not overloaded its a lowering spring that has been designed/made badly (in my opinion). You basically only have 3 coils that are allowing you movement. For those 3 coils to to take the weight of that corner of the car the actual coil needs to be much stronger. So you get very little movement for a bump and normally a harsh ride on anything thats not smooth road.

Much better to have no coils bound up and the same effective spring rate at the wheel. So when you hit a bump all 6/7 of the coils can move a little for the same wheel movement which gives a more compliant ride.

So if I bought some standard front coils (stillI progressive but not lowered) I’d sit 50mm higher?

 

But as I reckon I’m 50+kg heavier up front due to engine and gearbox swap, this would actually be nearer 20-30mm higher than it is now. 
 

Ideally I’d like it to be a bit firmer in the corners but not to compromise the comfortable ride too much.

With good quality parts it’s an expensive business so I can’t afford to get it wrong 😬

[Jessopia74]

25 minutes ago, Jonathan Pounsett said:

So if I bought some standard front coils (stillI progressive but not lowered) I’d sit 50mm higher?

 

But as I reckon I’m 50+kg heavier up front due to engine and gearbox swap, this would actually be nearer 20-30mm higher than it is now. 
 

Ideally I’d like it to be a bit firmer in the corners but not to compromise the comfortable ride too much.

With good quality parts it’s an expensive business so I can’t afford to get it wrong 😬

Wrong way up. You want the springs matched to your weight tbh, they sit in an optimal position within the compression zone of the spring. The set height is part of the calculation. Speak with TJ Motorsport as they can probably get you some 

https://www.tjmotorsport.co.uk/proddetail.php?prod=T24-09H

[Jonathan Pounsett]

3 minutes ago, Jessopia74 said:

Wrong way up. You want the springs matched to your weight tbh, they sit in an optimal position within the compression zone of the spring. The set height is part of the calculation. Speak with TJ Motorsport as they can probably get you some 

https://www.tjmotorsport.co.uk/proddetail.php?prod=T24-09H

I will. The Manta in the photo looks good an sits as it should. 

[cam.in.head]

all a matter  of opinion again as usual but yes as mentioned those look either wrong,badly made or knackered !.

if you like the ride quality now with those in then you may find the standard setup too soft for your liking. 

the cav was originally a pretty soft setup as standard and all models were basically the same. now i personally think that as standard they are one of the nicest handling cars around but obvoiusly not everyone will agree and prefer a stiffer setup.

to me that totally ruins the car and is why im running standard suspension on mine, ive been in others where they have mildly stiffened them up and found that the car is a different machine.way too hard .plus with all the speed bumps around and the way the exhaust hangs i wouldnt be able to drive anything around here that lowered at all( not that i would want to)

if it were me and you wanted a slightly stiffer setup i would go for standard springs all round.front ones are much easier to find in the original spec / style.but the rears which had a final turn either end of thinner material are very hard to source.all the aftermarket ones ive seen seem to just be a constant diameter throughout.

and then a set of sachs/ boge standard shocks. these are probably the people whomade the originals but ive found that the newer replacements are stiffer .maybee made to a different spec than factory issued ones. 

this should give you a slightly stiffer ride than standard. i  know  because i bought 2 sets of them many years ago rhinking i was doing good but when i fitted them they were the aforementioned "stiffer".

i sourced full sets of original GM shocks and also found some GM front springs too .( all on ebay of course)

best bet for a reccomendation before you buy and fit is drive another car equipped with the setup you may be considering.

ps is your track rod end locknut loose ?    lol 

[Jonathan Pounsett]

2 hours ago, cam.in.head said:

all a matter  of opinion again as usual but yes as mentioned those look either wrong,badly made or knackered !.

if you like the ride quality now with those in then you may find the standard setup too soft for your liking. 

the cav was originally a pretty soft setup as standard and all models were basically the same. now i personally think that as standard they are one of the nicest handling cars around but obvoiusly not everyone will agree and prefer a stiffer setup.

to me that totally ruins the car and is why im running standard suspension on mine, ive been in others where they have mildly stiffened them up and found that the car is a different machine.way too hard .plus with all the speed bumps around and the way the exhaust hangs i wouldnt be able to drive anything around here that lowered at all( not that i would want to)

if it were me and you wanted a slightly stiffer setup i would go for standard springs all round.front ones are much easier to find in the original spec / style.but the rears which had a final turn either end of thinner material are very hard to source.all the aftermarket ones ive seen seem to just be a constant diameter throughout.

and then a set of sachs/ boge standard shocks. these are probably the people whomade the originals but ive found that the newer replacements are stiffer .maybee made to a different spec than factory issued ones. 

this should give you a slightly stiffer ride than standard. i  know  because i bought 2 sets of them many years ago rhinking i was doing good but when i fitted them they were the aforementioned "stiffer".

i sourced full sets of original GM shocks and also found some GM front springs too .( all on ebay of course)

best bet for a reccomendation before you buy and fit is drive another car equipped with the setup you may be considering.

ps is your track rod end locknut loose ?    lol 

Thanks for the advice @cam.in.head. I have considered replicating the original setup but was concerned that it may not perform in the same way due to the additional mass of the V8 engine and box.

I have an enquiry in with TJ Motor Sport as suggested by @Jessopia74 so I’ll wait and see what they propose. The photo in the link that Jess sent is a manta with 15” Ronal which has great posture.

I was in the middle of adjusting the tracking when I took the photos. All nuts are tight now 👍

[mantasrme]

On 26/05/2022 at 11:10, Jonathan Pounsett said:

So if I bought some standard front coils (stillI progressive but not lowered) I’d sit 50mm higher?

 

But as I reckon I’m 50+kg heavier up front due to engine and gearbox swap, this would actually be nearer 20-30mm higher than it is now. 
 

Ideally I’d like it to be a bit firmer in the corners but not to compromise the comfortable ride too much.

With good quality parts it’s an expensive business so I can’t afford to get it wrong 😬

Ride height is a very difficult thing to predict. There are a lot of spring manufacturers out there and they make slightly different springs. For example a lot of ebay springs list the same spring for the front of a GT/e, exclusive, 1.8, and early b 1.6 which should be 4 different springs of different ride heights and different pundages for the type of ride the cars were designed to have. 1 spring will not be right for all those different cars. There are many instances of people fitting ebay springs and finding they now have monster truck ride height at the front of their car (The car SOS one being the most recent example of this). As for used springs they do sag over time and a lot of CIH engined manta's are sitting lower at the front than they did when new.

Aren't you running a rover V8? if so i'm sure i remember those engines weighing around the same as the standard manta CIH engine does. So ride height for a set of springs in a GT/e should be the same for your car (or very similar)

This is a picture of the front springs i use, they are 400lb progressive springs from On-lineAutosport via ebay as you can see the coils are all well spaced so the movement is spread between them all. They also put the ride height so there is some room between the end of the bumpstop and the lower arm. Something a lot of lowering do not do and leave you riding around on the rubber bump stops and crashing through pot holes

This is the ride height of a GT/e with those 400lb front springs, standard rear springs and bilstein dampers all round. I fitted this setup to replace the lowered front springs that looked very much like yours when fitted with the bunch coilbound one end. It crashed around and was generally very uncomfortable to drive on anything not smooth. The 400lbs springs transformed it into a nice ride that is a pleasure to drive.

[cam.in.head]

sorry didnt realise you had a different engine in there ( that will teach me not to read your whole post !)

but as said ,if the weight is the same as a 2.0 cih then the standard springs would be fine.

standard cih springs(not gte) seem plentifull on ebay .just be carefull and read the ad making sure (as stated) that you dont buy from one of the"one spring fits all type sellers) who dont know what theyre selling.

[Sutty2006]

Is it possible to get some links up to decent suppliers @mantasrme on eBay? I can’t find any. Mrwipers seams popular on there but again one spring for all! 

[cam.in.head]

mr wiper is the ones ive seen too. hehas listed ones suitable for cih engined models .

[Trooker]

4 hours ago, Sutty2006 said:

Is it possible to get some links up to decent suppliers @mantasrme on eBay? I can’t find any. Mrwipers seams popular on there but again one spring for all! 

Here’s a link to onlineautosport’s rear spring offering which isn’t what David’s recommending but they’re not listing their 400lb fronts tonight. You can probably contact them via eBay to check 

https://www.ebay.co.uk/itm/274434532751?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=kG0f-OQgTwm&sssrc=2349624&ssuid=7Tkc7MW4TEe&var=&widget_ver=artemis&media=COPY

[cam.in.head]

if it were me ! ( silly saying realy !) 

i would fit the standard cih fronts as on ebay from mr wiper.

source some good correct rear springs .used from a member or new if you can find any. i havnt ever found any in the last 10 years  ?

fit a set of boge/ sachs standard dampers.

anything else WILL change the cars character and handling.( some will say for the better ,others will say not,thats why i reccomend driving an original setup non gte,   a gte   and a car with aftermarket stuff just to see what suits you best. 

aftermarket stuff is obviously going to be easier to find over original .

 

[Jessopia74]

14 minutes ago, cam.in.head said:

if it were me ! ( silly saying realy !) 

i would fit the standard cih fronts as on ebay from mr wiper.

source some good correct rear springs .used from a member or new if you can find any. i havnt ever found any in the last 10 years  ?

fit a set of boge/ sachs standard dampers.

anything else WILL change the cars character and handling.( some will say for the better ,others will say not,thats why i reccomend driving an original setup non gte,   a gte   and a car with aftermarket stuff just to see what suits you best. 

aftermarket stuff is obviously going to be easier to find over original .

 

I know you love the std Vauxhall setup (god knows why, but that is why the Manta was always superior), but it would not work with the engine/gearbox setup chosen. 

Springs need to be matched to the axle weight they are carrying, and ride height required secondly. Rears need to be then matched to balance the load shift. There is a lot more to the suspension then just kind of guessing at it. Just my 2pence worth, nothing against your opinion on your personal preference here. 

[mantasrme]

13 hours ago, Sutty2006 said:

Is it possible to get some links up to decent suppliers @mantasrme on eBay? I can’t find any. Mrwipers seams popular on there but again one spring for all! 

These are the front springs https://www.ebay.co.uk/itm/Manta-B-Ascona-B-Road-amp-Rally-Front-Springs-400lb-/294999547702 they are not listed currently, they were a couple of days ago and were in my watch list. I'm sure they will be relisted soon, its just because of the way they seem to list them one at a time.

[Jonathan Pounsett]

As mentioned the V8 isn’t considerably heavier than a cih and whatever my springs were, they coped well with the 3.5 V8 on carbs I had previously. The car sat lever and the tyres looked right in the arches. I suspect these were the OE springs.

However as part of the restoration I moved on to a 4.6 V8 with fuel injection and also refurbished a GTE front crossmember it is now lower at the front by a good 40 or 50mm. 
 

I could just guess and go for new, non GTE, springs but can’t risk it. I’ve sent some info off to TJ Motorsport who I hoped would do some calculations but haven’t had a reply yet.

The only real change is the mass of the engine so someone with the formula should be able to make a reasonable recommendation. 🤞TJ Motorsport will get back to me soon.

[Jonathan Pounsett]

TJ Motorsport have recommended both 450lb and 600lb coils for a Manta with a normal cih engine.

450lb would look something like this;

And 600lb also with 15” Ronals similar to mine;

 

Does anyone know what rating the original Manta springs are? I’d like something just a bit firmer but don’t want to go crazy - I’m not in the Dukes of Hazzard!

Am I correct in thinking that if my engine is 100kg (say 200lb) heavier than the cih engine my car would sit 8mm lower with 600lb coils and 11mm lower with 450lb coils?

 

 

[Jessopia74]

It’s not as simple as that as they are progressive and the coils are wound to give the ride height at a given mass, that been said the compression in the first coils usual happens pretty quickly. https://suspensionsecrets.co.uk/how-to-calculate-coil-or-leaf-spring-rates/  is about the only site that might be able to help mate. 
 

Now if it does sit a bit low, you can add packers (they can be purchased with the spring profile) to help it back up.

I’ll see if I can find the post on FB for the rates used in rally car setups, but iirc they was 650 fronts .

What about going air? 

Edited June 9, 2022 by Jessopia74