GSXR 750 SRAD - Drag Racing Wheel Alignment

[blandit600]

Hi all,

I've been slowly building a GSXR 750 SRAD on the side for drag racing, slowing but surely its coming together.

It's nothing fancy, just dipping my toes into the sport and I had a spare frame, engine, forks, wheels etc etc lying around, so thought why not?

I've had an extended swingarm made and it looks great, ticks all the boxes, happy with the dimensions & quality.

However, the original wheel spacers no longer space the wheel to where its symmetrical with the bike and is offset approx 11mm to the right (looking from the rear, facing forward.

I've had some wheel spacers made, which now space the wheel as far over as it could possibly be, before I it clearance issues with the sprocket carrier rubbing against the inside of the swing arm. This new spacing brings the offset back 9mm, so the wheel is now 2mm off the centre line of the bike.

I have measured and re-measure the dimensions from various points of the frame in relation to the rear wheel before writing this post and to the best I can make out, the bike is "Straight" and the engine / swing arm centre pivot has be torques in the correct sequence to space things out as they should be.

So my questions is, will 2mm be noticeable? is this sort of normal, in the sense that are any motorcycles with an aluminium twin-spar frame "Straight"? I'm assuming perfect mm alignment is usually not something that is achievable? or am I wrong and this will effect the bike pulling to one side in a big way!

Hers a few pics of the project!

As always, thank you for reading and some opinions would be appreciated!

 

 

[Jonny]

As far as I know as long as the wheels are pointing the same way, you can get away with a fair bit of latitude and still be safe. I’ve heard of bike’s coming out of the factory being up to 5 mill out on alignment. I’m sure someone will correct me if I’m wrong. 

[TonyGee]

the problem with mass produced frames is getting them perfect,  I was told on a Suzuki course that a frame could be up to 3mm out at the headstock !!!!  but that was acceptable !!!!!!!    just like the adjuster marks  on a swingarm, you set them right and then do a wheel alignment and the wheels are out of line   we had 2 long alignment beams (made for the job) to get the wheels in line.  

[blandit600]

Ok perfect, thank you for your responses, I definitely felt like I was chasing my tail on an impossible task otherwise. 

[TLRS]

Probably won't notice. But if you want to improve anyway. The seal can be discarded if the bearing is sealed. And if the sprocket bolts are in the way an alternative could be disc bolts.

[blandit600]

3 hours ago, TLRS said:

Probably won't notice. But if you want to improve anyway. The seal can be discarded if the bearing is sealed. And if the sprocket bolts are in the way an alternative could be disc bolts.

Thanks, yeh I've checked this out, so the outside face of the sprocket carrier is the widest part of the rear wheel assembly, so If I wanted to get REALLY into it, I would remove the bearing seal and mill the sprocket carrier face, then if I needed more, then cut / shorten the sprocket bolts etc etc, but for 2mm? its A LOT of work for someone without access to a mill or lathe etc etc

So I'm going to roll with the 2mm offset, see how it feels, and go from there

Cheers all!

[BillyR]

Just my thoughts, but if the new arm has caused you wheel alignment problems, then me personally id be taking the arm back.

I had a similar problem way back when i had JMC make me a arm, yes i took a gamble as for every good arm they made, they made a shit arm.

Unfortunately they made me a shit one, wheel alignment was way out, so i took it back, 3 months later after pointing out i was seriously losing patience they sent me another, wheel alignment was great, but the pivot was now 30mm too wide for the frame.

I gave up and went to Spondon like i should of in the first place. 

[blandit600]

On 6/19/2023 at 10:26 AM, BillyR said:

Just my thoughts, but if the new arm has caused you wheel alignment problems, then me personally id be taking the arm back.

I had a similar problem way back when i had JMC make me a arm, yes i took a gamble as for every good arm they made, they made a shit arm.

Unfortunately they made me a shit one, wheel alignment was way out, so i took it back, 3 months later after pointing out i was seriously losing patience they sent me another, wheel alignment was great, but the pivot was now 30mm too wide for the frame.

I gave up and went to Spondon like i should of in the first place. 

the thing is, the swingarm is symmetrical, which I quite like, is a tough one, either get the swingarm remade with an offset in it so I can use the original spacers? or keep it symmetrical and just use different spacers? I had it custom made (not many places to get an extended swingarm off the shelf for an SRAD!) and by the time you take postage costs into account blah blah ill live with the spacers.

IF the wheel was off by 10+mm then this would be a different story.

Drag racing / extended swingarms is a whole new world for me! so lesson learnt for me, next time ill be more specific in my requirements.

Thanks all

[BillyR]

If everything else is great on it, and you dont mind working out some different spacers, then its not too big a deal.

But yeah its a bit annoying when you want a longer arm, and then get a longer arm, but with a new problem.

I cant see 2mm being a huge problem, and hey a tleast you are savvy enough to have noticed it, many wouldnt.