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69 front ride height, new springs/shocks

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kfosburg Avatar
kfosburg Karl Fosburg
Frederick, Maryland, USA   USA
1969 Triumph Spitfire "Spitfire"
I have read 20 threads on the subject and been through Paul's most excellent site... Couple of clarifications?

My car sits way too high in the front - about 24.75" with stock tire heights to the fender lip. Looks goofy and bugs me...

Shocks are in good condition all around, but was thinking of swapping them out just because to new KYB. I'm not looking to autocross or anything, just a decent ride with slightly better than stock handling which is already improved with modern tires.

2 questions -

Front spring rate - I've seen people talk about 9" free length with rates ranging from 220 to 350 lbs/in. I would prefer too low and and shim up if need be. I generally drive on decent roads and am not too worried about bottoming out. Any suggestions? Something in the middle is what I was thinking - maybe the 250# or maybe 300#...

Second - rear shocks... Will the rear ride height go up with the KYB shocks? If so, would I just need to put a lowering block to compensate?

Thanks in advance,

Karl

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GT6Mike Mike Hoffmann
Oakville, Ontario, Canada   CAN
I'm in the middle of one of These upgrades.

From what I've read you need the heavier 300+ front springs.

For the rear, changing the shocks will not change the ride height. Depending on age the rear may be riding lower. If you put a new spring in the rear, chances are you may need to lower it with a block to get it to match the front.

clshore Carter Shore
Beverly Hills, Florida, USA   USA
In reply to # 1465129 by GT6Mike I'm in the middle of one of These upgrades.

From what I've read you need the heavier 300+ front springs.

For the rear, changing the shocks will not change the ride height. Depending on age the rear may be riding lower. If you put a new spring in the rear, chances are you may need to lower it with a block to get it to match the front.

Actually, some shocks are 'gas charged', pressurized internally, and will affect ride height.
I believe KYB is one of those.

A better solution for a car that already has a sagging rear spring is to fit the Monroe air shocks.
These allow you to quickly and easily add/remove air using a standard Schrader valve setup,
to fine tune the rear ride height and camber to suit whatever load, or usage that you desire.
This mod has been performed successfully on our cars for at least 20 years now.

This can also be fitted to a car with a new spring, but you must fit a lowering block to allow the full range of adjustment.

Also, front ride height is determined by a combination of factors, not simply spring rate.

Fitted Spring Length = Free Spring Length - ( Fitted Load / Spring Rate )

This subject has been discussed and analyzed and explained a million times, do a search.



Edited 1 time(s). Last edit at 2017-06-18 10:03 PM by clshore.

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Yellowhawk Valley Avatar
walla walla, washington, USA   USA
1969 Triumph Spitfire "Walla Walla"
1969 Triumph Spitfire "Portland"
1972 Triumph Spitfire MkIV "Spokane"
1975 Triumph Spitfire 1500 "Dayton"    & more
We often find as well that if the rear is lifted to an accepted height, the front will also drop down slightly. Changing the front down usually does not affect the rear (as far as I have ever heard). I will suggest doing what needs on the rear first then looking at the front. As mentioned you can do new springs, air shocks, lift spacers as needed (to actually drop the frame/diff downward to adjust the camber), new rubbers in the existing rear leaves. etc. There several hundreds of discussion on here about the affects and the processes.
Dan

ExPatBrit Avatar
ExPatBrit Mike W
Redmond, WA, USA   USA
After equivocating for a year I just installed the Monroe air shocks this weekend, I used the MA 785 and the AK 64 accessory kit to provide individual fill schraeder valves.

I haven't experimented with left / right pressures yet just driven it around to get things to settle.

Even with both sides at the same pressure it appears closer in left/ right ride height than before with the old KYBs. It was an inch off before but now it's less than 1/2 inch.

kfosburg Avatar
kfosburg Karl Fosburg
Frederick, Maryland, USA   USA
1969 Triumph Spitfire "Spitfire"
Thanks for the responses... FYI - I did read up a lot of background information before asking.

Primary issue with "calculating" a new value for spring length/rate is lack of existing values - too many variables to solve the equation. I did take a stab at it with some assumptions and ordered up a pair of springs for the front. I was seeking more empirical data.

Back height is fine today, was inquiring is case I want to improve on existing.

I will respond back with some pics and results after I get my new front springs.

Thanks,

Karl

ExPatBrit Avatar
ExPatBrit Mike W
Redmond, WA, USA   USA
In reply to # 1465248 by kfosburg Thanks for the responses... FYI - I did read up a lot of background information before asking.

Primary issue with "calculating" a new value for spring length/rate is lack of existing values - too many variables to solve the equation. I did take a stab at it with some assumptions and ordered up a pair of springs for the front. I was seeking more empirical data.

Back height is fine today, was inquiring is case I want to improve on existing.

I will respond back with some pics and results after I get my new front springs.

Thanks,

Karl

Check for stuck front or rear trunnions or tweaked suspension arms or uprights. That was happening on my car when I got it.

Specs for a lot of Spitfire aftermarket parts are often fiction. I tried two sets of front lowering springs, the first raised the car like it was a motor-boat.

The second set dropped it 1 1/2 inches from stock, I added 3/8 spacers to raise it back up some. Last year I switched to 5/8 spacers instead as it had dropped over time.

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spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
In reply to # 1465242 by ExPatBrit
Even with both sides at the same pressure it appears closer in left/ right ride height than before with the old KYBs. It was an inch off before but now it's less than 1/2 inch.

Mike,
Try checking how hard it is to compress those old KYB shocks. Maybe you will find one much easier to collapse than the other.
All the best,
Paul

N5329K Avatar
N5329K Silver Member Robin White
Pacific Grove, CA, USA   USA
My nose was pointed way up when I bought the car. I discovered (with help from the people here on this board) that my spring perches were installed upside down. Reversing them allowed the springs to sit properly and brought everything level...front and back.
Robin

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ExPatBrit Avatar
ExPatBrit Mike W
Redmond, WA, USA   USA
In reply to # 1465282 by spitfire50
In reply to # 1465242 by ExPatBrit
Even with both sides at the same pressure it appears closer in left/ right ride height than before with the old KYBs. It was an inch off before but now it's less than 1/2 inch.

Mike,
Try checking how hard it is to compress those old KYB shocks. Maybe you will find one much easier to collapse than the other.
All the best,
Paul

Strangely both shocks appear to be OK (the same) .

Weather has been so-so here for the last week . I haven't driven far with the new Monroe air shocks, just enough to get the bushings to settle in. I assume the left side could start drooping again after some long spirited driving and I will need to adjust the pressures.

kfosburg Avatar
kfosburg Karl Fosburg
Frederick, Maryland, USA   USA
1969 Triumph Spitfire "Spitfire"
Update... Goal being a better stance with slightly improved handling...

Some numbers first.

The original springs were about 12.75" free length. Installed length about 8". Fender height with 165/60/13 tires was almost 24.75".

Ended up going with new springs up front, original shocks. No changes to the rear.

New Springs = 10" and 200#/in rate. QA1 10HT200 purchased from Amazon with Prime shipping about $98...

https://smile.amazon.com/dp/B014V3H9J6/ref=cm_sw_r_cp_dp_T1_NYQtzbV8GVXJR

First stab at it yielded about 6.25" installed length and only 22.5" fender height - too low. Installed 1/2" spacer brought it up to 23" in front which which looks just right. Rear height is 23.25"

Handling is definitely improved with better turn-in bite. Stance looks great and I can see out much better.

Karl


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Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, Nevada, USA   USA
Nice rake.

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