Stiff suspension
- Thread starter oino
- Start date
one finger john
Active Member
Chris, did you ever loosen up the front end. That had zero suspension travel.
John
John
I called Spirit today. They said thats normal for the front end.
They said I should change the spings in the rear to a 115 rate.
Ted Brown
Member
If all you want to do is a bolt in, then change the springs, if you can and want a better ride, move the springs forward, in front of the rear end, then you can still use the ones you have now, the more leverage on them, the softer they become... and no way is that correct to have the front with no suspension travel, talk about an unsafe setup, that can get you in trouble, you need some travel to keep from breaking mounts and everything else... 
Zero front suspension travel and Spirit says that's normal?
LumenAl
Member
I suspect what we have is a failure to communicate here... there is no way you should not have "suspension" on your front axle!
one finger john
Active Member
Allow me to clarify. When Chris was still living in Culver City, I visited him and was impressed by his build and the conditions in which it was built. When I saw it, the rolling frame was completed and engine/trans were in and running. This was in addition to radiator, head lamps, fuel tank but sans body & interior and steering column. I mentioned something about front suspension travel (car is equipped with friction shocks and front panhard bar) and asked to see the amount of front end travel there was. I weigh 210 lbs. and I placed my full weight on the front cross member and the suspension didn't move. Then I had Chris join me and our combined weight had to be over 400 lbs. . Still no suspension movement. Made sure that the shocks and panhard bar were disconnected. To my eye, no suspension movement. If I am raising a red flag over nothing then I apologize. But it appears that the front spring needs to lose a few leafs and if it were my car I would install hydraulic shocks.
Just my take on the situation, John
Just my take on the situation, John
one finger john
Active Member
If Chris is running just a pair of relatively light weight bucket seats instead of a full interior, then I can possibly see where he is having problems with a stiff rear suspension. A full interior weighs, what?, 200 lbs. or more. where buckets weigh less than a hundred. Since this is sprung weight ( meaning weight that is supported by by the coil springs ), then I would think that the coils should be more like 175 or 180 lbs. Drivers weight - 200 lbs, interior weight - 100 lbs., fuel tank + fuel - 100 lbs. est. ( sorry I don't know the lbs. per gallon for gasoline, I know he has a plastic 10 galleon tank ). So far 400 lbs with probably another 125 lbs for passenger and another 50 lbs. fpr misc ( fuel pump, etc. ) then you are looking at altogether 575 - 600 lbs. that would need to be supported by two rear springs.
If anyone sees anything that looks out of kilter, please post. Especially the estimated weights and the definition of sprung weight.
Are the rear springs progressives or are they straight wound. That can make a difference. Since the shock mounting is "stock" Spirit then I don't see a problem there. Also if the shocks are adjustable, where are they adjusted?
Lastly, don't expect a Cadillac ride from 2000 lb. car. Not unless you expect to spend ALOT of money and do a lot of engineering.
John
P.S. Another thought is to consult with Spirit instead of Speedway on this situation. I say that because Spirit designed the frame and suspension pick up points and might give you pointers to check as far as where the shock points on the rear end are welded, what length vs weight shock you should be running ( perhaps a longer shock? ). This is your first try at car building, don't try to second guess or go cheap on it.
If anyone sees anything that looks out of kilter, please post. Especially the estimated weights and the definition of sprung weight.
Are the rear springs progressives or are they straight wound. That can make a difference. Since the shock mounting is "stock" Spirit then I don't see a problem there. Also if the shocks are adjustable, where are they adjusted?
Lastly, don't expect a Cadillac ride from 2000 lb. car. Not unless you expect to spend ALOT of money and do a lot of engineering.
John
P.S. Another thought is to consult with Spirit instead of Speedway on this situation. I say that because Spirit designed the frame and suspension pick up points and might give you pointers to check as far as where the shock points on the rear end are welded, what length vs weight shock you should be running ( perhaps a longer shock? ). This is your first try at car building, don't try to second guess or go cheap on it.
one finger john
Active Member
O.K., last thought. Put a zip tie on each shock shaft so that you can see how much movement there is by how far the zip tie is moved when the car is driven.
John
John
Spirit has always used 140 and 150 pound springs in the rear. I have had a few customers that have put on 115 pound and 95 pound spring rate in the rear and they swear by it. Spirit is going to try that and see.
"The Bat" out of hell
Member
If coil over,ya can make mounts that let you lay over angle,if ther strait up and down now,letting them lay over up to 45* max cuts rate by about 1/2.
Many I see are mounted too close to center anyway,so moving out bottom of mount nearer tires helps ride and sway
Many I see are mounted too close to center anyway,so moving out bottom of mount nearer tires helps ride and sway
Ted Brown
Member
Sway should be a thing left to cars with top weight to worry about, a T Bucket has nothing that will cause body roll to speak of... The closer the springs and shocks are to the wheels, the more they have to move... As far as allowed movement, the U joints are the controller of/at this point, where the drive shaft connects (in the center) there is only so much up and down movement allowed at this point, and a travel stop needs to be mounted there... the outer wheels can move much more (one at a time) so by mounting stiff springs out more, will make the ride seem even more harsh with every bump, inboard (closer to the center) not so much... I can use any spring from most any car and make it work great, ride soft or firm, it all depends on where I mount it, how much leverage is working against it, same goes for shocks, where they are mounted and how much angle they are mounted on tells that story, the same shock will act in 10 different ways, depending on the mounting position... Note: shocks can be used for up body travel to stop that motion, but not for the down travel stop, will ruin the shocks to bottom out hard...
ellis8500
Member
Keep in mind that the inherent geometry of hairpin radius rods adds to suspension stiffness. Spirit told me they use 140 lb rear springs on the 27T and they are mounted at a 20 degree angle. A four-bar link suspension will not be as stiff with the same set of springs. The front sping is a different story. It will not sink much with static weight on the front. It is designed more for axle articulation; i.e. one wheel rising when you hit a bump, lowering in a pothole. On my 27T, once the engine is installed, standing on the front cross member doesn't do much. The spring shackles are already spread to their normal, outward posiion.
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