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  • 740 Suspension Upgrade Options

I am new here and reasonably new to Volvos. I am looking to up grade the suspension on my 740 and retain some of the comfort in the ride

I have read a number of web articles and forum articles about coil over upgrades and some of the inherent issues however I have still not come across someone who has done this and successfully kept the ride comfortable. That is, they have sorted the spring rate issue. From what I can gather the main issues revolve around the motion ratio of the suspension and not being able to purchase appropriate rear springs to correct the issue. I have looked at all of the reasonably affordable options like D2 and BC however there are issues such as what I have mentioned.

Why use a BC or D2 style set up ... because they are height adjustable without affecting the the spring rate and have adjustable damping control.

My 740 has the original suspension which is tired, the car still sits OK but the ride more resembles that of a boat. I want to lower it a little, improve its handling without sacrificing too much ride comfort as I am not building a drift car.

My project is 1989 740 sedan soon to be fitted with 377 cubic inch SBC, Holley Stealth EFI, Procharger, TKX 5 speed and 9 inch axle. From the research I have done there will be a marginal weight increase to the front so I realise I will have to make some allowance for this. As far as front end weight is concerned the Volvo Diesel D24T option is not all that different to a small block chev V8 with alloy heads.

Any help on the suspension side of things will be appreciated.

@AshDVS is the resident suspension guru and sells all sorts of solutions.

Thanks, I will send him an email and see what he has come up with.

From what you're saying, I would say why not try a Bilstein B6 (a.k.a. Bilstein HD) shock and some mild lowering springs. I used to run this setup in my 740 Turbo wagon as a daily driver and I liked it, the HDs really crisp up the handling without being harsh or uncomfortable.

I get what you are saying about adjistability, and depending on how much weight you add in the engine bay you would probably need to swap the front springs, but even then I think you'd get a more comfortable ride and spend less money and less time than a coilover conversion.

BNE Dynamics also make some really nice strut tops https://www.bneshop.com/collections/700-900-volvo-parts/products/700-900-spherical-adjustable-strut-mounts?variant=28941808969

Hi James, thanks for your input.

I have taken a look at some of those options however it is the adjust-ability that I was looking for. The standard suspension has been in the car since new (230K on the clock) so it will all need upgrading to some level. That is, springs and shocks all round. The fronts are coil over in any case, the BC or D2 are advertised as coil overs however the supplied rears are a standard set up with a height adjuster either under or over the spring with an adjustable shock and all as standard fitment locations.

The front springs will definitely need replacing but then I need to balance them against the rears. I have tried finding out the standard factory spring rates as a starting point but I have not had any luck there. I know they are identified by a colour band but that is long gone. I will get the car off the ground and measure up to calculate the motion ratio so I at least have that.

The install would be easy, more time would be spent getting the dampening balance set up. Looking at the price of bilstein shock absorbers then add springs, the cost would possibly be similar. But still and option. I will check out the BNE tops in any case. BC's 740 fronts and rears pictured. Different to what is shown on their website.

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Ash can work all that out.

Perhaps Ash can and so could I if I had a starting point to work from. This was the reason for asking if there was possibly someone else who had already done this and they would share the information.

The mathematical equation to get the motion ratio is not difficult if you know what spring rate gives a comfortable ride in the front. Then work backwards with that to get the rear spring rate. Then using adjustable shock absorbers to control the damping and smooth the ride. If the rear springs are too stiff then over bumps the rear tyres will have trouble keeping road contact and with that comes a hard ride and possible steering issues.

An old post I read from some years covered this exact problem with 740 sedan using BC's suspension kit. He worked out the problem however he never posted back any information about whether he managed to solve the issue. Using the lightest available rear spring he could find still left the car unbalanced and that was the issue, he was unable to find a suitable spring.

I have emailed Ash and I will see if he has a solution and or a recommendation.

Cheers

It is possible to convert the rear springs to take generic 65mm ID coilover springs, with or without height adjustment.

A lot of aftermarket “coilover kits” for cars with non-coilover suspension include bolt-on adjustable spring seats that both convert the car to the smaller ID spring and make the spring seat adjustable.

Eg:

It’s been ages since I had a look at the rear springs in a 7/9, so there’s potentially some pitfalls regarding spring length vs suspension travel, but I don’t think it will be a problem.

I'm led to believe the 740 Turbos had stronger springs than standard , a set of those and adjustable shocks maybe

I've had 2 black 740 Turbos , auto & manual , both handled well

I've had reply from Ash about my order and mentioned you , he is very busy.

Thanks for the input.

I have seen youtube videos where people are fitting proper coilovers (out of what is unknown) to the rear of volvos however from what I have seen I don't know if any consideration is given to what is actually installed regarding suspension travel and bump stops.

CMA (D2) has come back to me with what looks like a much better spring combination than the BC setup is supplied with.

D2 8.7 kg on the front and 4.2 kg on the rear. This is more like what I am looking for, Maybe even 1 kg less on the front

BC 5kg on the front and 6 kg on the rear. This to me seems to be backwards.

Thanks for the Raceland tip, I will check to see what they have to offer. I have done a search for proper coilovers for the rear of a 740 however what is available is all in Europe or the US and they are for the most specifically for race or drift applications. This is not for me as I want the car to be comfortable on the street, that is without loosening the fillings in my teeth. Also I was trying to by in Australia before going overseas.

Cheers Snoopy, I will wait for him to get in touch.

I know Ash has a few Coilovers options and can tailor springs to suit your build and what you need from it , even different rates for either corner to allow for driver etc...

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