GT6 non-roto spring and driveshafts wrong?

[Roger K]

The late '73 non-roto GT6 I have just bought is suffering with rather odd positive camber on the rear wheels.  I have checked back through the invoices that came with the car, and it turns out a few years ago the car was fitted with a new transverse leafspring, the part number of which ties in with a late non-roto Spitfire.  This is a different number to that for the GT6, so I have ordered the correct part.  However I'm confused, because the car has positive rear camber.  I would expect the GT6 to be heavier than a Spitfire, and therefore to use a stiffer spring.  Surely with the weaker Spitfire spring it should have negative rear camber?  Thoughts welcomed.

I'm wondering if the drivshafts are the correct length (although there's no record of them having been changed).  Could someone tell me the correct length of a late non-roto GT6 driveshaft, please?

Thanks, Roger

[Clive]

I cannot help with the driveshaft length..

However, there are plenty of rear springs that bear little resemblance to original spec. In fact I was unaware anybody made a proper later GT6 spring any more (GT6 has a thicker bottom leaf). So it may be that the one on your car was simply made with too much arch, too strong or both. Plenty of people end up fitting lowering blocks to get a more suitable ride height.

Hopefully the new spring will sort the issue though. They can take a while to settle, speeded up by heavy weight (eg 6 bags of sand in the back) and a few hump-backed bridges.

[Pete Lewis]

dont remember the shaft dimensions but a non swing shaft is 1/2" shorter than a 1500/gt6/111 long shaft 

can you tape measure the visible shaft length ??

edit,  the total hard to check lengths  all pre  non swinger    19.5"        late swingers  mkIV /1500  and GT6/3  20.5"   so theres an 1" difference 

Pete

[Nigel Clark]

26 minutes ago, Pete Lewis said:

dont remember the shaft dimensions but a non swing shaft is 1/2" shorter than a 1500/gt6/111 long shaft 

can you tape measure the visible shaft length ??

edit,  the total hard to check lengths  all pre  non swinger    19.5"        late swingers  mkIV /1500  and GT6/3  20.5"   so theres an 1" difference 

Pete

Exactly, and the extra length is inboard of the hub and brake backplate, so measure carefully to the drive shaft tip on the outside of the brake drum.

Nigel

[Roger K]

I'm planning a full rear end rebuild so once I get the driveshafts dismantled I'll be able to measure accurately.

I've bought a spring from Rimmers - it has a different part number from the Spitfire 1500 spring and is listed as only fitting GT6 Mk3 non-rotoflex, so hopefully it'll be right.  Its number is 159654 whilst the Spitfire IV and 1500 is 159650, which is what my car has currently fitted.

I'm used to settling leafsprings.  One of my cars has a front one and a back one, so double trouble!  As the GT6 spring settles, would that result in more negative camber?  I'd presume at rest the spring would sit with a downward curve at the ends, meaning that settling would produce more positive camber.

[Clive]

As the spring settles, you get more negative camber. The changing geometry is far more complex than it appears!

[Colin Lindsay]

12 hours ago, Roger K said:

I've bought a spring from Rimmers - it has a different part number from the Spitfire 1500 spring and is listed as only fitting GT6 Mk3 non-rotoflex, so hopefully it'll be right.  

That's correct, the two are quite different and made a world of difference when I swapped my swing-spring Spitfire spring on my GT6 for the proper GT6 version. It transformed the drive and bottomed out much less, despite looking thinner. 

I also found that the Spitfire spring fouled the rear brake cylinders as the ends were much larger than the GT6 version.

[Pete Lewis]

yes needs a real tight pipe bend out the cyl  to clear the eye wrap 

Pete