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Chassis Problems
myke pocock - 23/12/08 at 10:32 PM

Just had an illegal run down the road and back. Even with only 1300cc of standard x flow and the engine not tuned it goes like stink. HOWEVER some banging from the rear end. Turns out the top of the diff nose is fouling on tube 'O3' on suspension drop. The chassis is all as book as are the trailing arms. I have already in the past had to shave the edge off tube 'e' so that one of the diff nose side webs doesnt hit it (Mk 2 Escort axle) I am using ex Caterham 7 suspension. Anyone come across this problem before and what was the remedy? As the shockers are adjustable I will wind in the adjusting screw (Spax units) but I was also thinking of making up an alloy packer for the top of the coil over unit to raise the chassis and give more clearance.
In the mean time can I thank everyone on this site for all the listings and comments, many that have spured me on with my, (now 11 year!!!!) build. What a boost to the ego when you drive the car for the first time (even illegally)


blakep82 - 23/12/08 at 10:41 PM

hopefully my first drive won't be too far off well done!

have you got any photos? is the bodywork on? i thought, on a book chassis (remember i'm not building a 7, so never gave it much thought) the nose of the axle sat well behind any chassis tubes?


MK chippy - 23/12/08 at 10:51 PM

11 years! Hope my build goes a bit faster than that!

Can't wait till i start mine up for the first time!

[Edited on 23/12/08 by MK chippy]


MikeR - 23/12/08 at 11:00 PM

mine isn't ......... started officially in 2000.


blakep82 - 23/12/08 at 11:06 PM

bought my chassis in 2003. didn't really start it til about 2 years ago


omega0684 - 23/12/08 at 11:35 PM

you got a picture of where the diff is fouling?


myke pocock - 24/12/08 at 12:12 AM

No photo unfortunately (must learn how to do it sometime) but its fouling on the rear bottom corner of tube O3 if that helps.


DavidM - 24/12/08 at 12:46 AM

Here's a picture of the relative positions of everything on mine. With the trailing arms parallel to the ground the very top of the diff is about 10mm lower than the underside of O3.
I hope this helps, it's good to see another locost well underway.

David
[img] diff
diff
[/img]


procomp - 24/12/08 at 07:54 AM

Hi

Its a common problem that many of the manufacturers chassis had also. You can raise the ride height to give the clearance. But if the ride height you have is already 10-20 mm higher ( with driver on board ) at the rear compared to the front ride height you would be better off removing the chassis member and raising it. Its what the majority of the guys and gals racing in the locost championship have had to do.

But first things first are the ride heights actualy set to approximately where they will be when car is finished.

Cheers Matt

Edit. Just realised i did not say why raising the chassis was not such a good idea. If you raise the chassis you will encounter the problem where you have enough travel for the car to travel in bump ( chassis moving down ) but you will run out of travel in droop ( chassis moving up ). As can be seen on the pic above ( for example ) whith lots of clearance between the top of the diff casing and the chassis there is only what looks like 25mm for the chassis to travel upwards before the axle hits the chassis under the axle. There really needs to be around about 35-40mm clearance ( with driver onboard ) between the axle tubes underside and the chassis to give sufficient travel in bump and droop.



[Edited on 24/12/08 by procomp]


DavidM - 24/12/08 at 10:20 AM

quote:
Originally posted by procomp
Hi


As can be seen on the pic above ( for example ) whith lots of clearance between the top of the diff casing and the chassis there is only what looks like 25mm for the chassis to travel upwards before the axle hits the chassis under the axle. There really needs to be around about 35-40mm clearance ( with driver onboard ) between the axle tubes underside and the chassis to give sufficient travel in bump and droop.

[Edited on 24/12/08 by procomp]


With mine set up as the picture above my axle and diff have never hit any part of the chassis. There is about 25mm between the underside of the axle and the chassis, but this increases when driver and passenger get in. The shocks reach their full range of travel before anything hits anything else.
Mine has a number of differences to the book layout.

David


procomp - 24/12/08 at 10:35 AM

Hi

wasn't criticising the above. I could see from the piece of wood insitu it was in setup mode. Just using your pic as a explanation as it was conveniently there already. As you say with driver on board there will be plenty of clearance.

Cheers matt