Belly Tank Build Diary

[Mike Brown]

I finished up the bracket for the top suspension links on the rear end.  Not wanting to purchase a left hand thread boring bar I purchased a 3/4-16 left hand tap from Jegs.  It was the Allstar Performance brand.  I had to return it.  Even using the tailstock of the lathe to help push the tap and hold it straight it would not cut at all.  I purchased a tap from McMaster Carr and it worked perfectly. 

[Rex Schimmer]

McMaster and Carr!! If they don't have it you don't need it and if they do it is quality (none of that Chinese $hit!) and I get 2 day delivery from their warehouse in LA.

Love em!!

Rex

[Mike Brown]

A photo of the rear suspension.  This Hotchiss style link suspension does not need a panhard rod due to the triangulation of the links.  In my limited testing there is no binding with an inch of movement up and down.  I think I will use this suspension design for the front also. 

[John Burk]

Mike
With satchell linkage the roll center is at the level of the angled links . When they're all angled like yours it has 2 roll centers so the rear suspension is ridged  in the roll axis . Making either the upper or lower links parallel would fix that .

[Jack Gifford]

... the rear suspension is ridged [sic]  in the roll axis...

Assuming you meant 'rigid': I'm not seeing that. It looks to me that if the rears of the two top bars were moved to be together, there would be zero binding under any situation. And with them as close as they are, and with reasonably-limited suspension movement, there appears to be effectively no binding.

[John Burk]

Jack
With satchell linkage with the uppers angled the lowers must parallelogram for one wheel to lift . If all are angled none can parallelogram . The suspension can still go up and down but one wheel can't lift independent of the frame . The biggest problem is the stress it puts on the linkage and the twisting force where the axle tubes where they go into the side bells of the QC .

[SPARKY]

red neck solution  solid 

[ronnieroadster]

Mike it was great talking with you at Wilmington. I enjoy seeing your design work and the way you machined the parts. I'm looking forward to seeing the finished car at Wilmington in the future.
Ronnieroadster

[Mike Brown]

I have decided to use rubber as the suspension element.  The folks at Timbren have been very helpful.  Note the difference in compression and rebound on the deflection chart.  The rubber has a definite integral damping affect.

[Mike Brown]

I had some initial difficulties ordering a steering rack from Unisteer.  The original applications engineer thought the application was "dangerous" and was not all cooperative.  I finally contacted Brandon Kirby 800-338-9080 ext. 249 at Unisteer and was able to make it happen.  They still build a 1.2" per revolution steering rack which is the slowest that I could find.  They have a order form on their website for custom racks.  Fill in the dimensions and send it in.  They can quickly tell you if they are able to build it or if changes are required.  My rack will come complete with 5/8" rod ends for the 1/2" steel steering arms that I am using on the steering knuckles.  I am looking forward to getting the rack on July 20th. 

[Mike Brown]

The chassis is now a roller.

[manta22]

I have decided to use rubber as the suspension element.  The folks at Timbren have been very helpful.  Note the difference in compression and rebound on the deflection chart.  The rubber has a definite integral damping affect.

Mike;

That's called "hysteresis"-- the rubber does absorb energy-- that's why it gets hot.

Regards, Neil  Tucson, AZ

[Mike Brown]

I installed rubber springs made by Timbren in Canada.  They are very compact and have worked out well.  Timbren makes the rubber springs in a variety of shapes sizes and durometer.  The upper brackets were machined from 1" thick steel plate.  The upper mounts are threaded 3/4-16 with alloy threaded rod made into adjuster screws.  There is also a an aluminum adjuster that pilots inside the 1-1/4" hole in the rubber spring.  The lower mounts are 1/4" steel disks welded to 1-5/8" OD tubes coped to match each axle.  There is a 1/2-13 stud welded to each lower mount which allows the spring to be secured without squeezing it.  There is a spacer and steel washer inside each spring. 

[Jack Gifford]

Looks good. Do the springs have sufficient damping that separate shock absorbers are not needed?

Oops! I now see the rear shocks.

[Mike Brown]

Jack,

Per the rule book shock absorbers are required however just jumping on the frame it is amazing how much dampening there is in the rubber springs.  The compression rate is highly progressive and with the dampening in the rubber springs I don't think that I will need to run sway bars.  I attached a photo of the individual spring components.