Spitfire 1500 low front end, snags on wheel arches

[alan.gilbert_6384]

Hi All,

So done lots of measurements around the car.  The front appears to be low and not evern, off side floor to arch is 22' 1/4'' for off side, with near side being 22' 1/8''.  The spring length when car is sitting on ground and seated,

is 7' 6/10'' for offside, with 7' 3/10'' for near side.  The rear appears to be same both sides at 23'.  I have removed the ARB and check it using two levels to line up the straight and the other to bribe the fork ends, it appears straight.

So here is my plan (constructive comments would be greatly appreciated)

I looked at new springs, this is very confusing as most state an installed length of 7'' (I already have that and a touch) and there are lots to choose from if you want to lower the car, not so many for standard ride hight.  Normally in automotive design, the rack control arms are meant to set the OB's in their mid position, ie the rack and control arms and IB's are straight and level in both planes when the vehicle is in it normal state (this ensures least wear and positive centring of the steering as you drive).  But Spitfires seem very different.  The last one, at Gaydon, has a very high front end.  So I looked at spring spacers and thought how hard can it be to make my own, now just got to fit them, they are 3/8 thick so I am thinking two on the nearside and one on the off side ?  The wife is still looking for her favourite chopping board (you didn't see ANYTHING).

 

[alan.gilbert_6384]

Just now, alan.gilbert_6384 said:

Hi All,

So done lots of measurements around the car.  The front appears to be low and not evern, off side floor to arch is 22' 1/4'' for off side, with near side being 22' 1/8''.  The spring length when car is sitting on ground and seated,

is 7' 6/10'' for offside, with 7' 3/10'' for near side.  The rear appears to be same both sides at 23'.  I have removed the ARB and check it using two levels to line up the straight and the other to bribe the fork ends, it appears straight.

So here is my plan (constructive comments would be greatly appreciated)

I looked at new springs, this is very confusing as most state an installed length of 7'' (I already have that and a touch) and there are lots to choose from if you want to lower the car, not so many for standard ride hight.  Normally in automotive design, the rack control arms are meant to set the OB's in their mid position, ie the rack and control arms and IB's are straight and level in both planes when the vehicle is in it normal state (this ensures least wear and positive centring of the steering as you drive).  But Spitfires seem very different.  The last one, at Gaydon, has a very high front end.  So I looked at spring spacers and thought how hard can it be to make my own, now just got to fit them, they are 3/8 thick so I am thinking two on the nearside and one on the off side ?  The wife is still looking for her favourite chopping board (you didn't see ANYTHING).

 

I now ' for feet two for inches '' opps.

[Iain T]

I take it you have standard tyre width/profile? 

My Vitesse was too low and scraping the wheel arch when turning or over bumps. I bought gaz adjustable shocks and increased the ride height then had it set up with corner weights with 80kg on drivers seat. 

Iain 

[alan.gilbert_6384]

41 minutes ago, Iain T said:

I take it you have standard tyre width/profile? 

My Vitesse was too low and scraping the wheel arch when turning or over bumps. I bought gaz adjustable shocks and increased the ride height then had it set up with corner weights with 80kg on drivers seat. 

Iain 

Hi Iain, its on 175/70 13 these should be ok.

[Pete Lewis]

sounds more like a spring pan position than fitted spring lengths  are driving the low front end 

Pete

[AlanT]

Standard wheels? I fitted new, standard, springs (Rimmer) and 175/70 rubbed on 5.5J slot mags (just on bumps). Returned to standard 4.5J and 155, now no problems. 
My car rides sits low, despite being entirely standard. The one at Gaydon looks too high. 
175 could have worked for mine but with stiffer front springs. 

[Iain T]

1 hour ago, AlanT said:

Standard wheels?

Good point, a non standard rim may have different offset and wider track. 

Iain 

[Mark B]

The spitfire and gt6 did originally sit high at the front, as per the gayden Spitfire. People would comment on my mk2 gt6 sitting high at the front, but the car, although tatty and worn was untouched and original. I think over the years so many Spits and gt6's have been lowered it seems odd to see them at their original ride height. I did eventually lower and stiffen the front suspension, because to me cars look better lowered,  but regretted it, it rode better on worn original springs than the uprated firmer shorter aftermarket versions.

[chrishawley]

Here's some thoughts, not that I have in-depth knowledge in this area.

Seems perfectly reasonable to experiment with upper spring spacers. But how much spacing can be added at the top is influencecd by the length of the three studs which secure the (upper) pan. SIgnificantly more that 3/8th inch spacing could dictate the spacers are fitted at the bottom, between the spring and the pan on the shock.

AFAIK there was never an manufacturers definition of ride height for Spit/GT6. But I've deduced that 600 - 605mm (arch lip to floor) is possibly 'about right' as is a 'palm test': i.e. on the four corners the ability to slide in a flattened palm between the top of the tyre and the lip is also 'about right". I'd concur that back in the day Spits/GT6s commonly had a 'tippy toe' look.

Did the snagging come on after fitting a trunionless kit?

As regards tyres (and at risk of stating the obvious!): Although a 175/70r13 has a diameter little different from 155/80r13 it's nonethless the best part of a inch wider. Perhaps worth adding to the considerations.

For myself I'd probably not get too particular in ride heights (as measured by lip to ground) being a gnats difference from one side to the other. Sure, have to be reasonably level but there are variances in where the body tub and bonnet sit in relation to the chassis that the lips of the arches can't really be taken as datum points.

I'm interested to know how your further investigations and (hopefully) remedies proceed.

[dannyb]

My Spit 1500

Wheel arch 23 inch spring length 7.5 inch.

Sits low but plenty of room for 175/70 5.5J

Danny

[alan.gilbert_6384]

8 hours ago, Pete Lewis said:

sounds more like a spring pan position than fitted spring lengths  are driving the low front end 

Pete

Hi Pete, not sure what you mean by Pan position, please see pictures

[AlanT]

My suspicion is that replacement 'standard' springs sit lower than originals, probably in response to most owners preferring this look. What @Mark B says is true. The Spit I had 30 years ago sat far higher than my current car (it looked a bit odd because of this, like the Gaydon one does).

I've also been surprised at how 'soft' the current 'standard' Rimmer springs are vs. my memory of originals (and also relative to many modern cars). Perhaps they know most owners are no longer teenagers...OR they want to sell more expensive upgrade springs to anyone wanting other than standard tyres/rims.

[Pete Lewis]

a good few shockabsorbers have the spring platform in the wrong position.... but then i would expect  the fitted lengths would be wrong 

 

 

 

[NonMember]

Spring pan in the wrong place would affect ride height but the fitted length of the spring shouldn't change. The spring compresses according to the weight on it. 

[johny]

Trouble is if ride height too low with standard spring the shock could bottom out which would make for a harsh ride! 

[alan.gilbert_6384]

Gentlemen, update, great success.

So having gone to school and learnt only the metric system, then entering the real work, was taught the imperial system, I am now one of those ambidextrous measurement types that measure things to best fit ie 200mm x 2"

I've now fitted the spacers and have got 22" 7/8 (was 22"1/4 and 22"1/8) on both fronts arch to ground (increase of 3/4) with spring length when on the ground between the spring pan on the shock and the tower at 8" on both sides.  The rear is 23" both sides (was 22"3/4).  I fitted two spacers to the near side, and one to the off side.  I checked that the shocks were good and the same on both sides at 3"centre to spring pan, and both 10"free state.  It now rides much better as well, also the steering feel is both lighter and better.  It's not as high as the Gaydon car, but thankfully that is not what I wanted.  The tyre no longer scrap the inner arch

, yippee.