Lengthening Herald Wheelbase

[RobPearce]

6 hours ago, Adrian Girling said:

I've read that the herald classis tyre OD is 582mm and if I want to go to the full 680mm for my replica then 3.52 would be the exact number.  In this case, 3.69 would be within 5%

I think you may have your maths inverted. Bigger wheels make for longer gearing, as does a lower diff ratio (it's the ratio of input turns to output turns). So if you wanted to retain the Herald's 16mph/1000RPM you'd need a 4.8 diff. There was a 4.88 diff fitted to 948 Heralds but, in truth, the 4.11 is noticeably under-geared on a 13/60 and if your body is going to be lighter then you can definitely tolerate the longer legs. Many people fit the late Spitfire 3.63 diff on Heralds and don't find it too long, so if you stick with the 4.11 with your bigger wheels I think you'll be OK.

[JohnD]

That moderns have such wide wheels is a product of the move to MacPherson strut front, and semitrailing rear suspensions that don't suffer from excessive camber change, plus radials and radials with lower sidewall ratios, that  will not tolerate that at all.

The vehicles that have narrow 16" rims today are motorbikes!   Many in  alloy, which might not be the look you want, Adrian, but how about wire spokes?  Or, wire-look alloy??

Amazon.co.uk : Motorbike Rims

[Adrian Girling]

5 minutes ago, JohnD said:

The vehicles that have narrow 16" rims today are motorbikes!   Many in  alloy, which might not be the look you want, Adrian, but how about wire spokes?  Or, wire-look alloy??

Amazon.co.uk : Motorbike Rims

Nice idea, but I'm not so keen on the prices!  I wonder if someone can make steel wheels narrower - I've seen people who can make them wider...
I think I'd prefer fairly basic looking steel wheels painted the same colour as the car

 

[Adrian Girling]

3 hours ago, RobPearce said:

I think you may have your maths inverted. Bigger wheels make for longer gearing, as does a lower diff ratio (it's the ratio of input turns to output turns). So if you wanted to retain the Herald's 16mph/1000RPM you'd need a 4.8 diff. There was a 4.88 diff fitted to 948 Heralds but, in truth, the 4.11 is noticeably under-geared on a 13/60 and if your body is going to be lighter then you can definitely tolerate the longer legs. Many people fit the late Spitfire 3.63 diff on Heralds and don't find it too long, so if you stick with the 4.11 with your bigger wheels I think you'll be OK.

OMG, thanks for correcting my maths - can I do an embarrassed emoji in this forum?  Yes, the propshaft needs to rotate more often to achieve the same road speed....  and I'm liking the logic of leaving it as it is 😀
 

[Adrian Girling]

Quick update, I bought the Herald on Ebay and have taken off the doors, bonnet and front bulkhead. I've lifted the whole of the rear end body and dropped it again as I've nowhere to put it!  The chassis seems to be in surrisingly good condition - that was my biggest risk.  Does anyone need these complete body panels?  They are not perfect, but not bad either.  Where necessary some good welding has been done already and I can take photos if anyone is interested.

 

 

[thescrapman]

Where abouts in the country are you Adrian?

[JohnD]

Where to put the body, Adrian?   In the roof!

Here's a very old pic, my first Vitesse, Old Blue, in restoration.  Two sets of pulleys in the roof beams and I lifted it off the chassis.   

NB instructions in the workshop manual.   The advice to reinforce the joint between the bulkhead and rear tube, at the sills, is a Good Idea! 

[Adrian Girling]

2 hours ago, thescrapman said:

Where abouts in the country are you Adrian?

Hi, I've sent you a private message.  I've now been recommmended to hang on the the rear section and the bulkhead for a while as it's been suggested I could cut them about (make them narrower) and weld on side panels (as my project car has no doors) to be stronger than a plywood frame.  Not sure if this will work, so they may be available later

[Adrian Girling]

2 hours ago, JohnD said:

Where to put the body, Adrian?   In the roof!

Great idea!  Slightly nervous about it hanging above me whilst working on the chassis!  A tad domoclesian I'd say.  Mine's a rag top so it comes off in two bits.

And thanks for the strengthening advice 🙂

[JohnD]

Ah!  Convertible!    Deffo add struts across the doors before you take it off.     Essential for Spits, recommended for Heralds/Vitesse, unless they have a roof to do the same.

Once it's up, add some security lines?    Ratchet straps?   But the weak point(s) will be where it's hung, the  roof beams or whatever.   I've heard of people building  a wooden frame to support the body, wide enough to wheel the chassis in and out to work on.  Then the weight is  on the ground, as long as the frame is strong and braced.

John

[Adrian Girling]

7 minutes ago, JohnD said:

Ah!  Convertible!    Deffo add struts across the doors before you take it off.    

I've heard of people building  a wooden frame to support the body, wide enough to wheel the chassis in and out to work on.

Oops, too late.  Bulkead is off, on it's side.  Lifted the back end high enough with a engine hoist to inspect under, now dropped back on chassis.  I've lifted a MX5 Unibody onto a wooden frame on casters this way - 38 x 63 timber studding is so versatile.  Thanks for the tips

[Spider]

I think I would have gone for a Reliant Scimitar chassis and shorten that.

 

[Adrian Girling]

8 hours ago, Spider said:

I think I would have gone for a Reliant Scimitar chassis and shorten that.

Fair comment Spider, I did look at that.  Several reasons why not.  It has a wider track width, not by a lot, but enough to make it difficult.  Bigger engine - with my lighter body the Herald engine will give more than enough power.  And the nose of the replica slopes down from about the front axle (vertical plane) which means I need to move the engine back about 110mm and by extending the chassis by 90mm just behind the rear lower wishbone I will effectively position the engine far enough back to squeeze in a radiator.  I was reasonably confident in advance that the engine in the Herald can be moved backwards as the two litre six cylinder can squeeze into the Vitesse.  Finally, I think the Reliant is a rarer beast, so they are significantly more expensive to buy.  The Herald I bought is good for me as the chassis is in great shape, and the body not so good, so it wasn't too expensive!

But I can tell you, the guy who sold me the body shell has actually used a Reliant to build a similar but wider and longer car with alumunium bodywork for a friend who is about 6ft 3in tall and can't fit in the seriously narrow original car.