Front shock modification 101
Posted: Sat Feb 21, 2009 11:33 am
I decided to upgrade from the stock widebody suspension for a couple of reasons. The main being the obvious improvement to the handling that comes from better shocks and heavier springs, while the second was to change from the stock spring seats to adjustable to gain greater clearance for bigger wheels and tyres and to lower the car. I own a widebody so this obviously applies to widebody (hereby designated WB) starions, but the Australian delivered Starions are very similar and the following will still work with slight variations. Unfortunately I don't have narrowbody (NB) suspension to check these details on and I'm hoping that any holes in the information can be filled by other members. Please feel free to add anything you think might help with the ultimate aim to create a complete resource for anyone thinking of upgrading the suspension on their Starion. My understanding is that the WB struts are longer than NB struts, but I'm not sure on specifics.
FRONT STRUTS
It's no secret that aftermarket bolt-in shocks are not freely available. Most that I am aware of need to be imported and it could be argued that they are a compromise to performance and more of a stock type shock. I am not aware of any adjustable shocks manufactured for the Starion (other than old SHP shocks). If we take the assumption that adapting a shock designed for another car as the best option then a huge range of shocks become availble - everything from cheap gas shocks for a daily driver to all out racing shocks for the most excessive starion on the track. I personally chose to use Koni adjustables as I have used them in the past and they are not a bad balance between performance and price.
My first take was to try and fit a shock into the stock strut body. The donor car that I settled on was commodore VB-VP front shocks. These will bolt into the WB starion strut body and the thread for the gland nut is the same. The only thing that needed modification was the spring top cap and strut tops due to a larger diameter thread. These shocks can also be modified to fit NB struts by grinding the knob off the base (see pic below). This modification was done and fitted to my JB many years ago.
The simplicity of the 'bolt-in' choice was soured by the fact that when sitting the car at my preferred ride height there was not enough travel to the bump stops, and the shock had too much travel to hold my springs captive (even with helper springs). Cue angry sounds from me at realisation that my new $600 shocks wouldn't work for me. However they would be fine for a daily driver at a sensible ride height and the slightly shorter NB struts would also help. I used these shocks in my JB for years and there was no problems with hitting bump stops and the lowered springs were captive.
The solution was to select a shorter shock. I had heard about MR2 shocks being used in the US and luckily Bodeo had a pair for sale that I purchased. Because they are shorter the strut body has to be cut and shut to suit, but I gained the benefit of more travel to bump stops and the springs would be captive. The added bonus is that the thread diameter at the top is the same as Starion so no further modifications required.
Part numbers;
Commodore VB-VP front 86-2076 SP1 (red adjustable) 8641-1066 sport (yellow adjustable)
MR2 SW20 2.0 t/c rear 8641-1221 sport (yellow adjustable)
Unknowns;
Are Commodore/MR2 shocks the same dimensionally between different shock manufacturers?
Are MR2 gland nuts threaded the same as Starion? The nuts didn't come with the shocks as I purchased second hand, and I can use the commodore ones. Will need to purchase some from koni to check (hopefully they will sell separately).
Shock comparison;
TOP - Koni yellow MR2 shock (my final choice)
Koni yellow Commodore shock
Koni red Commodore shock (as fitted to JB)
BOTTOM - stock widebody damper
Commodore red vs yellow (note knob ground off on red to fit NB;
Shortened MR2 equipped strut vs Stock length Commo equipped;
Assembled front strut (needs repaint after cut'n'shut);
Still to come;
Rear struts
Fitting adjustable spring sets, part numbers
Shortening strut tubes.
FRONT STRUTS
It's no secret that aftermarket bolt-in shocks are not freely available. Most that I am aware of need to be imported and it could be argued that they are a compromise to performance and more of a stock type shock. I am not aware of any adjustable shocks manufactured for the Starion (other than old SHP shocks). If we take the assumption that adapting a shock designed for another car as the best option then a huge range of shocks become availble - everything from cheap gas shocks for a daily driver to all out racing shocks for the most excessive starion on the track. I personally chose to use Koni adjustables as I have used them in the past and they are not a bad balance between performance and price.
My first take was to try and fit a shock into the stock strut body. The donor car that I settled on was commodore VB-VP front shocks. These will bolt into the WB starion strut body and the thread for the gland nut is the same. The only thing that needed modification was the spring top cap and strut tops due to a larger diameter thread. These shocks can also be modified to fit NB struts by grinding the knob off the base (see pic below). This modification was done and fitted to my JB many years ago.
The simplicity of the 'bolt-in' choice was soured by the fact that when sitting the car at my preferred ride height there was not enough travel to the bump stops, and the shock had too much travel to hold my springs captive (even with helper springs). Cue angry sounds from me at realisation that my new $600 shocks wouldn't work for me. However they would be fine for a daily driver at a sensible ride height and the slightly shorter NB struts would also help. I used these shocks in my JB for years and there was no problems with hitting bump stops and the lowered springs were captive.
The solution was to select a shorter shock. I had heard about MR2 shocks being used in the US and luckily Bodeo had a pair for sale that I purchased. Because they are shorter the strut body has to be cut and shut to suit, but I gained the benefit of more travel to bump stops and the springs would be captive. The added bonus is that the thread diameter at the top is the same as Starion so no further modifications required.
Part numbers;
Commodore VB-VP front 86-2076 SP1 (red adjustable) 8641-1066 sport (yellow adjustable)
MR2 SW20 2.0 t/c rear 8641-1221 sport (yellow adjustable)
Unknowns;
Are Commodore/MR2 shocks the same dimensionally between different shock manufacturers?
Are MR2 gland nuts threaded the same as Starion? The nuts didn't come with the shocks as I purchased second hand, and I can use the commodore ones. Will need to purchase some from koni to check (hopefully they will sell separately).
Shock comparison;
TOP - Koni yellow MR2 shock (my final choice)
Koni yellow Commodore shock
Koni red Commodore shock (as fitted to JB)
BOTTOM - stock widebody damper
Commodore red vs yellow (note knob ground off on red to fit NB;
Shortened MR2 equipped strut vs Stock length Commo equipped;
Assembled front strut (needs repaint after cut'n'shut);
Still to come;
Rear struts
Fitting adjustable spring sets, part numbers
Shortening strut tubes.