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-   -   Noob with a new mx5 Saturn build. (http://www.haynes.co.uk/forums/showthread.php?t=13638)

vmax1974 8th June 2015 09:41 PM

They are quite tight and stiff on my car if all else fails shave a few thow off the bush

PorkChop 8th June 2015 11:37 PM

Stiff arms seem like a bad idea to me, wouldn't you be essentially preloading the wishbones?

Mine rotate pretty freely between thumb and forefinger, they're dry assembled at the moment.

It would be worth checking whether the bushes are binding on the mounts, there's probably going to be witness marks if they are.

Rosco 9th June 2015 07:41 AM

looking nice mate! seems like ages ago when i was at your stage, about 7 months ago and im nearly ready for powder coat!

TalonMotorFabrication 9th June 2015 08:56 AM

I think the whole crush tube,bracket and polybush thing needs putting in to context some what here.
The polybushes rotate around the crush tubes and rub against the sides of the suspension brackets and every thing is new when you are assembling the wishbones or moving them by hand you only exert may be 30-40lbs of force, a fully built 550-600kg car and 250-300lbs springs will find it much easier to move. You need to take normal wear and tear in to account before you introduce fore and aft movement in to the wishbones by shaving bits before they have had a chance to bed in on the road. The polybushes on these cars are seen as consumable and they will bed in after a 150-200 mile shake down, after 2500-3000 miles they will need replacing.

norton 9th June 2015 09:12 AM

Ah yes, I understand the weight of the car vs weight transfer, bumps etc will likely overcome the friction in the bush however, these bushes are bulging out of their intended home, something is less than ideal here I'm sure. At this rate I could probably run the shocks without any damping!

TalonMotorFabrication 9th June 2015 09:38 AM

When I bend my suspension brackets they end up being wider at the bottom and lean inwards at the top, try flaring them out a little and refitting the wishbones. The other thing I would look at is the inner diameter of the bush tubes, inner edges of the bush tubes have they got a lead in chamfer to them and are you using a vice to assemble them?

norton 9th June 2015 10:02 AM

I'm using a vice yes. The inner tube and brackets measure up perfectly. That chamfer is missing though and I can see they're not sitting right up against the housing tube. Out with the file then :(

CTWV50 9th June 2015 10:42 AM

Quote:

Originally Posted by norton (Post 100813)
Ah yes, I understand the weight of the car vs weight transfer, bumps etc will likely overcome the friction in the bush however, these bushes are bulging out of their intended home, something is less than ideal here I'm sure. At this rate I could probably run the shocks without any damping!

I dry assembled mine initially and the stiction on the rear was terrible. After the IVA I disassembled the lot and reassembled with teflon grease. The rear is nice and smooth now. If your bushes are buldging then you might want to check your tolerances or maybe there's too much grease in there?

norton 10th June 2015 09:45 AM

I've worked the outer tubes on one arm to ensure the bushes fit perfectly then measured the id of the bush. 18.5mm? The crush tubes are 19mm. Looks like I have an interference fit! The outer tubes are the correct I'd so they're not compressing the bush just gripping it.

Are my bushes no good?

TalonMotorFabrication 10th June 2015 09:58 AM

Quote:

Originally Posted by TalonMotorFabrication (Post 100812)
I think the whole crush tube,bracket and polybush thing needs putting in to context some what here.
The polybushes rotate around the crush tubes and rub against the sides of the suspension brackets and every thing is new when you are assembling the wishbones or moving them by hand you only exert may be 30-40lbs of force, a fully built 550-600kg car and 250-300lbs springs will find it much easier to move. You need to take normal wear and tear in to account before you introduce fore and aft movement in to the wishbones by shaving bits before they have had a chance to bed in on the road. The polybushes on these cars are seen as consumable and they will bed in after a 150-200 mile shake down, after 2500-3000 miles they will need replacing.

Don't forget you don't have any weight acting on the bushes yet, the weight of the car acting on the wishbones and polybushes will soon compress the top quarter section of the bushes.


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