Front spring perch questions

[Zandoz]

I see perches from various sources listed as dropped by varying amounts. Is the amount of drop measured from the the center line of the front cross member?

Is it feasible to use a perch with enough drop to end up with the bottom of a 3" frame rail about 5" off the ground, using a 4" drop spring behind axle? I'm worried about the amount of torque on the cross member. How much of a perch drop would this require?

 

[PotvinGuy]

I'd request dimensioned drawings from each perch maker. I doubt there is some standard. Are you using someone's frame? I'd first try to use their perch, spring, axle, etc. Mixing parts is a crap shoot.

 

[Zandoz]

I'd request dimensioned drawings from each perch maker. I doubt there is some standard. Are you using someone's frame? I'd first try to use their perch, spring, axle, etc. Mixing parts is a crap shoot.

I've not decided what I'm going to do for a frame. Right now I'm trying to accumulate some knowledge so I can make that decision. This is going to be my first venture into built from the ground up.

 

[RPM]

We make all kinds of front perches, we can make what ever you want. We have them that mount the spring even with the bottom of the tube all the way up to a 8" drop. Then with any tube size you need including round, square, and rectangle. Then we have them with different width springs. Lots of different combinations on perches.

 

[Youngster]

The best way to figure this is to mock up your frame and front end. Another way would be to check out other builds to see what they have done and the parts they used.

Ron

 

[T-Test]

The best way to figure this is to mock up your frame and front end. Another way would be to check out other builds to see what they have done and the parts they used.

Ron

And to add to Youngsters answer, the scrub line is most important as well as oil pan clearance.

 

[Zandoz]

We make all kinds of front perches, we can make what ever you want. We have them that mount the spring even with the bottom of the tube all the way up to a 8" drop. Then with any tube size you need including round, square, and rectangle. Then we have them with different width springs. Lots of different combinations on perches.

It sounds like you have what ever I need covered...Cool! You mention up to an 8" drop....how is that 8" measured? From the top of the cross member tube? From the middle?

 

[2old2fast]

As far as "torque applied" to the crossmember , if it's at least 2 1/2 x 3/16 DOM , I wouldn't suspect any trouble...

dave

 

[Zandoz]

The best way to figure this is to mock up your frame and front end. Another way would be to check out other builds to see what they have done and the parts they used.

Ron

I had planned on doing a mock up later this summer, once I accumulate the motor, transmission, and rear end. For right now I'm playing around with an old CAD program, as I accumulate dimensions. I'm hoping to be able to find opportunities this summer to get out and see other folks cars.

The reason I'm not going for an "off the rack" frame is that I'm disabled and need to make the step in height as low as possible, and also have the ability to have a wheelchair carrier mounted on the back. I'm 2+ years off from spinal surgery, and just recently able to drive again....something I never thought I'd be able to do again. This project is going to be a kind of an ongoing celebration for me.

 

[Zandoz]

And to add to Youngsters answer, the scrub line is most important as well as oil pan clearance.

With this thing being as low as I'm planning, I intend for the bottom of the pan to be a hair higher than the bottom of the frame rails.

 

[Zandoz]

As far as "torque applied" to the crossmember , if it's at least 2 1/2 x 3/16 DOM , I wouldn't suspect any trouble...

dave

I've been thinking along the lines of 3" x 1-1/4", .25" wall for the frame rails. I'll probably use either 3" round or the same size rectangular for the front cross member. Is there any structural advantage for one shape over the other?

 

[TrackTV6]

Given the same wall thickness and alloy, round tubing is stronger. I had a shop "press brake" my rails out of .125 cold roll and then boxed them with .125 cold roll. I would say .250 might be just a tad excessive. Just my thoughts.

 

[HenrysT]

It sounds like you have what ever I need covered...Cool! You mention up to an 8" drop....how is that 8" measured? From the top of the cross member tube? From the middle?

When you order things and you want a certain size, dimension,shape etc., be specific! I was, and I got off the rack stuff, and when I complained about it " I was to picky"... and he doesn't want to fix his mistake.

You should look into some sort of air bag or hydraulic suspension system so you can drop on the ground to get in and out and then raise it for cruising

 

[Youngster]

I agree with Henry. I usually don't go the air bag route but in your case it could be just the ticket. If you "raise" your engine where the pan is above the frame rail, you will lose a substantial percentage of your interior space.

Ron

 

[Zandoz]

When you order things and you want a certain size, dimension,shape etc., be specific! I was, and I got off the rack stuff, and when I complained about it " I was to picky"... and he doesn't want to fix his mistake.

You should look into some sort of air bag or hydraulic suspension system so you can drop on the ground to get in and out and then raise it for cruising

 

[Zandoz]

When it comes time to do material ordering I plan to have a race car chassis builder friend go over exactly what I need. If I get lucky and he's not busy at the time, I'll have him build the frame.

 

[Zandoz]

I agree with Henry. I usually don't go the air bag route but in your case it could be just the ticket. If you "raise" your engine where the pan is above the frame rail, you will lose a substantial percentage of your interior space.

Ron

Unfortunately I do not have the budget for something as fancy as a custom bagged suspension. Other than the frame, this is going to be an "off the rack" project. I know that the raised engine and transmission will cut into precious space, but it's a necessary compromise for me. This is the reason I'm planning on a '27 bucket, and automatic. Also, I'm planning on the seating position being higher than I'd otherwise like.

 

[Chief-T]

delete

 

[Chief-T]

Unfortunately I do not have the budget for something as fancy as a custom bagged suspension. Other than the frame, this is going to be an "off the rack" project. I know that the raised engine and transmission will cut into precious space, but it's a necessary compromise for me. This is the reason I'm planning on a '27 bucket, and automatic. Also, I'm planning on the seating position being higher than I'd otherwise like.

This bucket was at the NTBA Nats in Colorado Springs in 2010. I don't know who owns it but someone else may. It is really in the weeds and may help you in your planning.

 

[Lee_in_KC]

That is Dave "Eggy" Eggebraaten's car. He is in Canyon Lake, TX. E-mail is xxxeggebraa10@gmail.comxxx (remove the x's). He has a Jag rear-end with bags. He said he really doesn't have much in the rear set-up, dollarwise. He doesn't run a compressor. He just has regular tire-type air valves in the bags and adjusts with an air hose. That is one of the smoothest riding Ts I have ever ridden in.