Spitfire on bad road surfaces

[cliff.b]

The Spit 1500 I bought last week is now running & braking well enough for some proper road testing. Covered about 60 miles today and all going well until what I can only describe as some "weaving" set in. Considering the issues I have already found I thought something was about to come loose and stopped immediately to check everything out but all seemed ok. So drove off again tentatively and all fine until I hit a patch of badly repaired road and similar again, although not as bad but that's probably because I was travelling more slowly.

So I would be grateful for any opinions as to whether this might be due to 

1) The tyres that the car came with. (185/70 rear 185/60 front) or the tyre pressures.

2) some other suspension issue.

3) They all do this but I have forgotten over the last 40 years since I last drove one.

Since I realised nothing is falling off I have just driven through it ok, it's just a bit disconcerting.

 

 

[Clive]

Rear tracking would be my first guess, if that is out it can be very "exciting"

Next, are they standard type shock absorbers or adjustable. If adjustable, what make. Many people adjust shocks to "halfway" which can be dreadfully hard causing serious handling issues. (not on Koni though)

Front tacking/camber/caster or bumpsteer may need looking at, especially the car has lowered springs.

The tyres are a little too wide for std 4.5 rims, but if running at about 25psi should not cause major issues.

[DanMi]

have you checked for play in any suspension bushes and the front trunnions. Jack 1 end up and then lever at all the joints to see if there is any excess movement, the bottom of the front trunnion is notorious for having the bolt seize and wear out the plastic bushes. also check to see if the steering rack can move within it's bushes and for play in the track rod ends. Also check the rear bushes. plus check for free play in the steering universal joint any of these can cause poor handling particularly on poor roads and I would advise checking on a car new to  yourself anyway  

[cliff.b]

18 minutes ago, clive said:

Rear tracking would be my first guess, if that is out it can be very "exciting"

Next, are they standard type shock absorbers or adjustable. If adjustable, what make. Many people adjust shocks to "halfway" which can be dreadfully hard causing serious handling issues. (not on Koni though)

Front tacking/camber/caster or bumpsteer may need looking at, especially the car has lowered springs.

The tyres are a little too wide for std 4.5 rims, but if running at about 25psi should not cause major issues.

Thanks, Clive. There's nothing about the shocks that lead me to think they aren't standard. The ride doesn't seem hard. The springs also appear standard although of course the lower profile front tyres slightly lowers the front of the car. Could that be causing problems. One thing I have noticed, despite the pressures being higher than you suggest I can actually rock the car laterally from side to side due to the flex in the tyre side walls. 

[Badwolf]

Cliff, go into your original post, click on the three dots in the top right, you can then edit your post including the title and sub groups.

[cliff.b]

3 minutes ago, Badwolf said:

Cliff, go into your original post, click on the three dots in the top right, you can then edit your post including the title and sub groups.

Thanks. Now corrected 👍

[cliff.b]

42 minutes ago, DanMi said:

have you checked for play in any suspension bushes and the front trunnions. Jack 1 end up and then lever at all the joints to see if there is any excess movement, the bottom of the front trunnion is notorious for having the bolt seize and wear out the plastic bushes. also check to see if the steering rack can move within it's bushes and for play in the track rod ends. Also check the rear bushes. plus check for free play in the steering universal joint any of these can cause poor handling particularly on poor roads and I would advise checking on a car new to  yourself anyway  

I have checked a lot of it at the front when I was changing the calipers. Many of the bushes, nuts, bolts etc. looks new, but I agree, I need to look at everything. I'm not seeing any noticeable play at the wheels when I turn the steering wheel so assumed the steering UJ, bushes  & rack mounting are OK. Does this seem a reasonable assumption?

I haven't checked anything at the rear yet but will do so when I replace the brake shoes.

[Pete Lewis]

toe in the simple way

 

[cliff.b]

13 minutes ago, Pete Lewis said:

toe in the simple way

 

Thanks. I will have a read.

[Clive]

1 hour ago, cliff.b said:

Thanks, Clive. There's nothing about the shocks that lead me to think they aren't standard. The ride doesn't seem hard. The springs also appear standard although of course the lower profile front tyres slightly lowers the front of the car. Could that be causing problems. One thing I have noticed, despite the pressures being higher than you suggest I can actually rock the car laterally from side to side due to the flex in the tyre side walls. 

Lower profile tyres won't make a difference bumpsteer. 

Have you used std tyre pressures? 

But check teh tracking as Pete has suggested, it can make a car feel terrible.

[cliff.b]

1 hour ago, clive said:

Lower profile tyres won't make a difference bumpsteer. 

Have you used std tyre pressures? 

But check teh tracking as Pete has suggested, it can make a car feel terrible.

I have been trying various pressures to see how it feels but today, when the issue occurred I was running 28 front & 30 rear.

On normal road surface it felt good to me. I might try lower and go back over the same road, perhaps a bit slower this time 🙄

[Pete Lewis]

bump steer and bunny hops steers on bumps with the weaving indicates serious rear wheel toe errors 

two planks and a tape measure will show it up   only  takes a few minutes 

messing with pressures may change the ride comfort but has no effect on weaving or pot hole side steps/  bump steer 

pete

[cliff.b]

55 minutes ago, Pete Lewis said:

bump steer and bunny hops steers on bumps with the weaving indicates serious rear wheel toe errors 

two planks and a tape measure will show it up   only  takes a few minutes 

messing with pressures may change the ride comfort but has no effect on weaving or pot hole side steps/  bump steer 

pete

The body was removed from the chassis during the restoration work so am I right in thinking that the rear alignment should have been checked/corrected after that? 

[Mathew]

3 minutes ago, cliff.b said:

The body was removed from the chassis during the restoration work so am I right in thinking that the rear alignment should have been checked/corrected after that? 

Depends on if they did . Or did they just bolt it together? Check it or have it checked, unless you can ask them.

[cliff.b]

11 minutes ago, Mathew said:

Depends on if they did . Or did they just bolt it together? Check it or have it checked, unless you can ask them.

Unfortunately, I have no idea who carried out the restoration work. I bought the car last week off a guy who bought it "restored" last year but it rapidly became a non runner. I think I have to assume it wasn't checked after re-assembly and do it myself. 

[Mathew]

At least you know its done right if you do it yourself.

[cliff.b]

Planned to check the rear toe situation today but I cant find suitable straight edges at the moment. However, I have made a quick visual check of where the shims are placed and the OS gap appears significantly larger than NS. It looks like a solid block about a quarter of an inch thick. I will investigate further later and hopefully check the toe but just wondering if this amount of "shimming" is within the range of what is expected?

[Clive]

Look on youtube etc, there are various ways to centerline the car, use string, bricks and all sorts to check the alignment. But there is no correct amount of shimming as std. A friend had his car set up on a proper jig, and he has loads of shims one side. But the figures are all spot on in teh middle of the acceptable range.

The other tool is a gunsons trackrite, so simple to set toe, front or rear.

[Paul H]

7 minutes ago, clive said:

Look on youtube etc, there are various ways to centerline the car, use string, bricks and all sorts to check the alignment. But there is no correct amount of shimming as std. A friend had his car set up on a proper jig, and he has loads of shims one side. But the figures are all spot on in teh middle of the acceptable range.

The other tool is a gunsons trackrite, so simple to set toe, front or rear.

Plus 1 on the Gunsen Trackrite

[Pete Lewis]

to check how centre line it is  its easy with another 6ft long bit of something pretty straight 

put a brick against the rear tyre 

sit timber against tyre on brick  so you are above the wall bulge

sight the run of the timber along the sill line 

it should be  a  almost parallel gap 

check to compare other side of car 

if there a wild variation add remove shims to get both parallel to the body line and with the correct toe 

Trackrite  worth every penny 

dont ignore the fact that the spec for the car will most likely need 150lbs on each seat (thats  2 x for a spitty) to set the static ride height or you waste your time and money

check the spec  or ask on here   

 if no 150lbs bags of coal  .............get rent a crowd in for a party in the car

static ride height is something all auto centres will have not a clue about    its very very  important  

you may find there are unladen specs about  but that needs a bit of homework 

Pete

 

[cliff.b]

1 hour ago, Pete Lewis said:

to check how centre line it is  its easy with another 6ft long bit of something pretty straight 

put a brick against the rear tyre 

sit timber against tyre on brick  so you are above the wall bulge

sight the run of the timber along the sill line 

it should be  a  almost parallel gap 

check to compare other side of car 

if there a wild variation add remove shims to get both parallel to the body line and with the correct toe 

Trackrite  worth every penny 

dont ignore the fact that the spec for the car will most likely need 150lbs on each seat (thats  2 x for a spitty) to set the static ride height or you waste your time and money

check the spec  or ask on here   

 if no 150lbs bags of coal  .............get rent a crowd in for a party in the car

static ride height is something all auto centres will have not a clue about    its very very  important  

you may find there are unladen specs about  but that needs a bit of homework 

Pete

 

I found I did have something straight in the garage. I measured between the doors & it's 1484mm immediately behind the wheels & 1488 at the front end (near the bonnet.

[Clive]

Is that front or rear wheels? Either way,it has a little toe-out. Adjust so parallel to 2mm toe in. Front and rear.

[cliff.b]

23 minutes ago, cliff.b said:

I found I did have something straight in the garage. I measured between the doors & it's 1484mm immediately behind the wheels & 1488 at the front end (near the bonnet.

Forgot to put the pic on doh

[cliff.b]

I also raised the straight edge higher and measured gap to front sill edge (see pic). This was approx 5mm on NS and 10mm on OS, which is the side with more shimming. So I guess that would make sense. I'm thinking I should be reducing the shims on the offside?

[Colin Lindsay]

Reducing the shims will pull the front edge inwards.