JSPEC Springs changed for UK Spec

[georigg]

Just changed the springs on my Jspec Aero for a set of UK springs(courtesy of Bignum).... UK springs reportedly softer than Jspecs.

 

First impressions.

I changed the rears first and then the fronts the next night, so had the opportunity to gauge both situations against original Jspecs.

 

For info I had replaced the front & rear shocks about 3 months ago, and checked over the whole suspension to ensure there was nothing needing replacement, so I feel the comparison is valid given that the shocks are relatively new.

 

Rears only changed.

Car sits slightly higher at the rear---about 1". Whereas normally jspec springs provide a very firm ride with a bit of slow speed suspension "chatter" on less than smooth roads(which might be more to do with the tyres I have fitted which are relatively "stiff" on the sidewall), the car now appears to run smoother at lower speeds.

Usually with the Jspec springs you need to be travelling at about 60-70MPH before the suspension "smooths out". Front doesnt feel too bad, with slight harshness on rough/pot-holed road surfaces.

After fronts changed out.

Had thought there would be a marked difference in smoothness but frankly cannot really say there is much difference between Jspec fronts and UK fronts fitted........may be a very small difference.

 

Would I recommend this change?

For those of you looking for a "smoother" ride without the harshness of the Jspec suspension set up, my feeling is that it probably would be enough to change out the rear end springs on their own.

 

This is, however just an opinion and it would be interesting to hear comments from some of our suspension gurus on this.

 

If I had paid £100 per spring(Toyota's price for new ones) I might have been disappointed with the result, however I hope this info will help anyone else contemplating this change.

George

[SteveC]

Not sure if you're still around George, you don't appear to have been on here for about 6 months...

 

Just seen this post - interesting write-up. I notice you say that the UK Spec rear springs made the back end about an inch higher than when using the J-Spec rear springs; did it ever settle down much at all, or did it remain around an inch higher?

 

The reason I ask, is that when I replaced the original stock shocks on my UK Spec with Bilstein Sport shocks, it lowered the front end by about 10mm and raised the rear end by about 5mm. This was due to the spring seats on the Bilstein front shocks being 10mm lower than those on the stock UK spec shocks, but on the Bilstein rear shocks, the spring seats are about 5mm higher than those on the stock UK Spec shocks.

 

As it stands at the moment, the rear end is about an inch (25mm) higher than the front end. It doesn't look bad at all and it rides well, but the thought just crossed my mind that a set of rear J-Spec springs may just level it up - although I don't like the sound of this "suspension chatter".

 

Just for reference, with Bilstein Sport shocks and stock UK springs, mine (wheel centre to top of the arch) is front 345mm, rear 370mm.

[Chris Wilson]

Bilstein changed the spring seat height on their dampers at some stage. Sometimes you get the old style with stock perch height, sometimes the new style. There seems no way of knowing which, the part numbers didn't

change. This is from personal observation, Bilstein don't appear to acknowledge this.

[SteveC]

Thanks Chris for the info.

 

I did e-mail Bilstein a while ago asking why the spring seat heights were different to stock; this was the reply I received:

 

regarding your a.m. e-mail we kindly inform you that these types was produced especially for the Japanese market. There are the changing of the series very desired.

 

Hoping to have been of service to you and remain

 

with best regards

 

It didn't really explain anything...

[SteveC]

Just had a thought regarding Bilstein's change of spring seat heights:

 

If I've got it right, on a standard J-Spec, the front sits quite high compared to the rear. Perhaps Bilstein were trying to address that by lowering the front and raising the rear?

 

I'll attach a couple of photos showing the difference between stock UK Spec shocks and the Bilstein Sports shocks.

 

Front LH photo, rear RH photo.