Z900 front disc thickness

[sean_rfi]

Hello All,

I'm currently reassembling a 76 Z900 A4. It was originally a US import and therefore arrived with a single front brake disc.
I have now acquired all the parts for a twin disc upgrade (including a rare as rocking horse poo) NOS RHS caliper hanger.
My original disc which is in good condition is 7mm thick (standard for a single disc, I think) and I have managed to buy another identical 7mm disc.
However, I have read that the twin disc set up had two 5mm thick discs.
My question is would it be ok for me to use two 7mm discs or should I try and find two 5mm discs.
The only disadvantage I can thin of it that two 7mm discs will add more to the unsprung weight at the front.

[Garry.L]

You'll be fine with the two 7mm, from memory earlier Z1's were this anyway. It was only the introduction of the A4 which reduced to 5mm for (as you say) the unsprung weight.

[Mathh]

I have the twin 7mm's as well. They are heavier than the 5mm ones. I read some complaints from others about that. Ride the bike and if the weight does not bother you (when cornering or switching from left to right or vise versa) keep them. I was not bothered and still have them on the bike.

[sean_rfi]

Thank you both very much for the replies.
I'll build with the 7mm discs and see if how the bike handles - I don't suppose it adds up to great deal of extra weight..

[Mathh]

I don't suppose it adds up to great deal of extra weight..

That is hard to say, it depends on the weight, the bike, the rider...
A while ago I decided to swap the 4mm thick / 300mm diameter front discs on my Tracer 900 with 4mm thick 320mm diameter discs. I had to take them off as i could not take a normal corner anymore: the bike wanted to go straight everytime....