Ride height change with lowering springs - for reference

[Z320]

On 6/9/2023 at 11:03 AM, BaulyCars said:

A short spring calculation?

Original spring is about 260 mm long, in the car 170 mm, compresion 90 mm, load about 500 kg, spring rate 500 kg/ 9 cm = 55,55 kg/cm (310 lb/in)

The spring above is 225 (beginning) / 475 (strong part) lb/in, the soft part of it is 1/ (1/225 - 1/475) = 427 lp/in. 427 "+" 475 together 225

Check with the formular of springs in a row: 1/225 = 1/427 + 1/475

Assuming the soft part is not fully compressed with the car on the road (this is what you want!) the lenght fitted in a TR4A-6 is:

260 mm - 500 kg / 0,454 kg/lb / 225 lb/in = 260 mm - 4.9" = 135 mm (not at all 170 mm)

4.9 " is 2.58" on the softer part (fully compressed or not?) + 2.32" on the stronger part.

Very likely this spring doesn't fit at all on a TR.

Ciao, Marco

Edited June 10, 2023 by Z320

[BaulyCars]

Nice work, Marco, this is great, 

So that spring would drop to a 135mm installed length, versus the 170mm of the original spring, so the car would be lowered by 45mm from original?

That seems like an ideal rideheight drop, with a softer spring (my car dropped 50mm with 650lb springs).

I'm probably missing something... 

[Z320]

Yes but no,

45 mm on the spring is 90 mm on the wheel arch.

You will get a lovely low rider 

[BaulyCars]

 might look good!  OK, so progressive springs don't work either. 

What did you think of my lower spring pan idea, I'd appreciate your thoughts on that.  

Nice long spring, but lowered rideheight (the 'unicorn' of set-ups....)

 

[Z320]

I told you most what I did at Juni 3rd,

I did not lower or modify the spring pan and never considered what are the consequences of that

Ciao, Marco 

[Malbaby]

14 hours ago, BaulyCars said:

 might look good!  OK, so progressive springs don't work either. 

What did you think of my lower spring pan idea, I'd appreciate your thoughts on that.  

Nice long spring, but lowered rideheight (the 'unicorn' of set-ups....)

 

I think that correctly made progressive springs would work very well providing the internal diameter is adequate.

From your pic the "progressive" spring appears to be wound in two distinctive pitches...ie..hard and soft sections rather than a gradual transition from soft to hard.

The cost of making a true progressive spring is a question that only the manufacturer can answer.

And would they have a computer program for the design??

A lowered spring pan on a TR4A/TR6 would have a minimal effect...Different story with a TR4 that has a different design shock/spring tower that could accomodate coilovers.

Marco's idea of lowering the lower shock absorber attachment to increase the choice of suitable shocks is a good one.

Lowering our cars is problematic, as adequate ground clearance to the front cross member requires consideration.

Unfortunately no one makes a "dropped" spindle [the ideal solution] for our TR's.

Edited June 11, 2023 by Malbaby

[Z320]

btw the spring rate of your new front springs from post #1 should be

500 kg / 0.454 lb/kg / (204 mm - (170 mm - 45/2 mm) / 25.4 mm/in = 495 lb/in

Edited June 11, 2023 by Z320

[BaulyCars]

1 hour ago, Z320 said:

btw the spring rate of your new front springs from post #1 should be

500 kg / 0.454 lb/kg / (204 mm - (170 mm - 45/2 mm) / 25.4 mm/in = 495 lb/in

Thanks, Marco, that's sounds better than the 650 lb/in quoted for the spring

 

[BaulyCars]

6 hours ago, Malbaby said:

I think that correctly made progressive springs would work very well providing the internal diameter is adequate.

From your pic the "progressive" spring appears to be wound in two distinctive pitches...ie..hard and soft sections rather than a gradual transition from soft to hard.

The cost of making a true progressive spring is a question that only the manufacturer can answer.

And would they have a computer program for the design??

A lowered spring pan on a TR4A/TR6 would have a minimal effect...Different story with a TR4 that has a different design shock/spring tower that could accomodate coilovers.

Marco's idea of lowering the lower shock absorber attachment to increase the choice of suitable shocks is a good one.

Lowering our cars is problematic, as adequate ground clearance to the front cross member requires consideration.

Unfortunately no one makes a "dropped" spindle [the ideal solution] for our TR's.

I saw somewhere a drop spindle for a GT6 that someone cut and re-welded to make a drop-spindle (I think by Canley Classic, not sure).

Quite popular on classic muscle cars and lots of availability (Wilwood etc). 

Complex to figure out geometrically to do a TR version?   

 

 

[dblenk]

Hi

not quite as per the thread but did the yanks have a highier ride height than the uk set up

cheers

david

[Malbaby]

The Americans have their cars higher so that they can "Keep their big wheels turning for proud mary" 

[dblenk]

So std springs will bring it back to the UK look i checked moss USA but no spec length for the springs

any friends o er the water confirm ???

david