LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently September 23, 2020, 1:13 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 12 posts ] 
Author Message
PostPosted: July 23, 2019, 12:36 am 
Offline
User avatar

Joined: November 11, 2013, 4:47 am
Posts: 1282
Location: No. Nevada
How to get suspension travel on TR4 rear leaf springs?

Problem is that the axle sits OVER the frame.
The Dio Tipo body weighs almost nothing.
There is not enough weight to compress the leaf springs at all.
So the axle is sitting on the frame.
Great for bump but leaves me with zero droop travel.

Looking for the simplest least expensive fix.
Remove some short spring leaves?
Cut-off the rear of the frame and convert to 4-Link and coil overs?

Need to keep it authentic to a privateer 60's Special as it's to be a sort of re-creation build.

_________________
If I must be a one-man PC free zone, so be it!


Top
 Profile  
Reply with quote  
PostPosted: July 23, 2019, 8:22 am 
Offline
User avatar

Joined: January 2, 2009, 1:45 pm
Posts: 1257
Location: Halifax, Nova Scotia
Different spring shackles? Longer or shorter depending on what the mounts are .... Otherwise, take a couple of leaves out.

_________________
Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


Top
 Profile  
Reply with quote  
PostPosted: July 23, 2019, 9:24 am 
Offline
User avatar

Joined: February 2, 2017, 1:02 am
Posts: 70
Location: Illinois
I would definitely take a leaf or two out and retest. If that doesn't get you close enough could the springs be re arched at a spring shop?


Top
 Profile  
Reply with quote  
PostPosted: July 23, 2019, 11:00 am 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 5535
Location: West Chicago,IL
Removing leafs (leaves?) is the normal method to reduce spring rate. I would also consider poly or graphite inserts to reduce stiction. There are formulas out there on the interweb. But simple trial and error would certainly work. I'd also consider a rubber bump stop to eliminate any immediate changes when the axle does meet the chassis.

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE


Top
 Profile  
Reply with quote  
PostPosted: July 23, 2019, 12:00 pm 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6656
Some pics would be awesome.
Sounds like the shackle attachment point on the frame is too low. It should be at least a couple inches above the frame rail. With the axle hanging by the stock springs, there should be at least an inch of clearance between the axle tube and the frame. This would be a good time to set pinion angle without shims. Point the pinion at the front ujoint centerline. Fine tune later if needed. Use a $10 ebay digital protractor for best results.
If you want to soften it up, remove the 2nd shortest spring without alignment brackets. I would also de-arc the tips of each leaf so it does not dig into the longer one next to it and will reduce sticking. Use a hydraulic press to adjust the arc as needed with small tweaks along the length every couple inches. Plastic can be used between leaves but buttons require drilling and strips need to be full length to stay aligned so a lot of strips versus a little on the end.

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
PostPosted: July 23, 2019, 2:29 pm 
Offline

Joined: February 22, 2017, 10:47 am
Posts: 8
Location: Raleigh NC
Hmmm, it seems that everyone has already covered all of the things I was going to suggest, i.e. removing a leaf(s), using longer spring shackles, or getting custom flatter springs. The last, of course, also gives you the opportunity to get the spring [i]rate[i] you want as well as the height. And since you said you were looking for the simplest least expensive fix, have you considered keeping 5 or 6 35# buckets of cat litter in the trunk? That should do the trick, and it will certainly help the car rotate at turn-in. However it might also help the car (over) rotate in the middle of the turn, at turn-exit, in esses and high speed sweepers, on offramps, while going straight, etc. :P

_________________
JB


Top
 Profile  
Reply with quote  
PostPosted: July 24, 2019, 6:56 am 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6656
I didn't realize you were building two cars, one with a custom frame and one on the tr4 frame. Since you must be referring to the tr4 framed car, then the location of the shackle eye is probably correct.

Here is a pic of the stock setup. There is clearance between the axle and frame when the frame is jacked up and the axle is hanging by the springs. There is a spacer between the spring and axle. There are a couple different springs for the tr4. It is possible your springs are not correct and have too much arc, reducing frame clearance.

Removing a leaf and/or adding to the existing spacer (called the "distance piece") will increase frame clearance.


Attachments:
tr4 axle.jpg
tr4 axle.jpg [ 424.89 KiB | Viewed 1676 times ]

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447
Top
 Profile  
Reply with quote  
PostPosted: July 24, 2019, 8:02 am 
Offline
User avatar

Joined: June 20, 2019, 12:34 pm
Posts: 287
It is a problem when there is not enough weight or the spring rate is too high for the new configuration. Back in the 70's I had a Devin bodied TR and the suspension was like a old wooden wagon since it had the stock springs on it. Hitting a bump caused the car to bounce up in the air and skitter sideways.

Did not have the car long enough to correct it, but talking to a local MG racer at the time, he had suggested, as others here, taking out a few springs. Also, don't forget to address the shock rates.


Top
 Profile  
Reply with quote  
PostPosted: July 24, 2019, 10:56 am 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 5535
Location: West Chicago,IL
Miatav8,MstrASE,A&P,F wrote:
I didn't realize you were building two cars, one with a custom frame and one on the tr4 frame. Since you must be referring to the tr4 framed car, then the location of the shackle eye is probably correct.

Here is a pic of the stock setup. There is clearance between the axle and frame when the frame is jacked up and the axle is hanging by the springs. There is a spacer between the spring and axle. There are a couple different springs for the tr4. It is possible your springs are not correct and have too much arc, reducing frame clearance.

Removing a leaf and/or adding to the existing spacer (called the "distance piece") will increase frame clearance.


Won't adding to the distance piece/spacer increase (exponentially?) spring wrap under acceleration and braking?

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE


Top
 Profile  
Reply with quote  
PostPosted: July 24, 2019, 4:45 pm 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6656
Yep! I didn't say spacers are the best way to go, but I'd expect something like this to have 60's torque link/traction bars to counter those affects. We are not talking about much. By taking out a leaf, we are probably talking about a 1/2-3/4 spacer but it should not be touching as-is so "strange things are a foot at the circle K".

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
PostPosted: July 25, 2019, 4:02 am 
Offline
User avatar

Joined: November 11, 2013, 4:47 am
Posts: 1282
Location: No. Nevada
Four leaves in the springs.
Hoping I can get good result by taking out one and maybe adding 1/2" to the distance piece.
Think I need to add some steel, rear battery, and a mock-up drivetrain to see where I'm really at.
The main issue of the moment is that I have NO droop travel.
I suppose I should ditch the lever shocks too. :wink:

If this does not look like it's going be good I will bite the bullet and convert to four-link.
That would mean a pretty drastic cutting of the frame.

Tomorrow I need to decide, steel or aluminum flywheel.
With that bought I will be fully committed to the Buick V6/Saginaw 4-speed. 8)

_________________
If I must be a one-man PC free zone, so be it!


Top
 Profile  
Reply with quote  
PostPosted: July 25, 2019, 7:46 am 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6656
Cup half full here, as all you have is the droop ride height. Mount the body to the frame so the fender gap is what you want with the tr4 at original ride height then rework the springs to get it to sit at that height with reduced weight.

If removing the one spring isn't enough to reach the TR4 stock ride height with the reduced weight, using a friction disc or a thin disc in an angle grinder or chop saw (too hard for bandsaw), cut off a few inches of a spring with two alignment guide clamps. There is no need for two guides. If you take off too much, tractor supply has trailer springs (must be the right width) you can modify (length and arc adjustment with press) or old triumph springs off ebay to bring the rate back up or reinstall the original removed spring. Shorten it as needed so it cannot overhang or hit the guide on the next longer spring in the stack under full compression.

If the center bolt can't be reused, use an allen if the head is big enough for a tight fit to the distance piece or grind a hex head bolt down to the needed od to locate the axle on the spring. There usually is no way to hold the pin head to loosen the stack except vise grips. Just grind it off (with the stack c-clamped) if it causes much difficulty.

Since you are trying to keep it era correct, I'd keep the knee dampers if they are working properly. Not sure if they sell rebuild kits for those. Easy to find non-gas charged damper applications that won't jack up the car for cheap.

I put a buick v6 in a chevette in the 80s. :cheers:

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 12 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY