SX REAR MOUNTED SHOCK MOD

[Chrislong]

By making my own Saddle Lipo chassis out of the Schumacher stiff chassis, and making a Brass Lipo retaining brace which hold the rear 1/3rd of the cells. My weight bias is now 57% to rear, it was 54% before.

[Carlos69]

Would be interested to see some pics Chris

[Carlos69]

....

[MHeadling]

Myself and Spud31 ran the Sch SWB kit last night indoors at Faversham (polished wood floor) , Rich seemed to like it but I found it very snappy and tail happy to drive, put it back to normal wheel base now.

[Garry Spice]

Originally Posted by Mark Headling

Myself and Spud31 ran the Sch SWB kit last night indoors at Faversham (polished wood floor) , Rich seemed to like it but I found it very snappy and tail happy to drive, put it back to normal wheel base now.

aye,thats what i found mark.i changed my back aswell.

[discostu]

Originally Posted by Garry Spice

aye,thats what i found mark.i changed my back aswell.

hey gaz did you watch the vid on you tube of faversham watch my cat it doesnt snap or step out of line once.

stu

[stefke]

Just a little warning for those using the mod and using extra droop and 3°+ rear toe-in on the CAT : keep an eye on your driveshaft seating in the outdrives. I had mine pop out during our nationals last weekend.

Shimming the driveshafts proved enough to remedie the situation.

[PaulUpton]

To try and help you guys doing the mod, I found that with the suspention on the rear this gave the car alot more weight transfer, and with the long ball joints on the shocks this made the rear loose on entry into the corner and the front push out the corner, now having gone back to the short the ball joints this has stopped both these problems, hope this helps!

[bender]

Now that there are a few of us running the SX at my local low-grip dirt track, we are finally starting to improve the car for Aussie conditions. My car was handling and jumping very well, with the rear shock mod fitted for the first time.

However, I'm still not convinced that its effect is that great, and I believe that the mods greatest grip improvement comes from the sweep of the drive shafts, rather than the ballast difference by having the shocks out the back.

I've done a few calculations and discovered that moving the shocks to the back is only moving around 2.5% of the mass back approx 6.7% and moves the wing back only 3.2%. How much this contributes to improving grip is debatable, especially as my own car was never really lacking in grip to start with.

The biggest improvement in my car has been the fitting of Tamiya shocks from the 501x, which certainly improved the cars handling over the bumps.

Next meeting I will be trying something else, running the shocks at the front of the arm again, but modifying the arms so that the wheelbase is reduced a further 2-3mm from the kit "short" position. This should result in a similar wheelbase and driveshaft sweep compared to reversing the arms, but still allows the shocks to be in their original locations.

The next step is to try and get the motor as far back as possible. I'm switching to the 80t spur for the next meeting but it would be better if Schumacher made down to a 75t spur I think, though perhaps it would be difficult to get the right ratios with some of the hotter mod motors.

[Chrislong]

Im using a 78tooth Losi spur on mine - for motor position. Any smaller and I can't mesh the pinion.

Im on 78/23 on a 5.5 Speed Passion.

I am using the car as standard, I felt the driveshaft angle locked the shocks on power not allowing them to absorb bumps - felt very skitty to me... I tried several ways of doing it, and it was at no point better than the std mounting position.

[B&H Racing]

Chris - Any mods to fit a on a Losi Spur Gear ?

[mikeyscott]

Originally Posted by discostu

hey mark here are the pics ive alterd the shock tower mountings since wednesday i think you will agree this is better.

stu

Did you change anything else?

Also is that a Tekin RS Pro in the car?

[bender]

Originally Posted by Chrislong

Im using a 78tooth Losi spur on mine - for motor position. Any smaller and I can't mesh the pinion.

Yep, unfortunately I've just discovered that - with the 80t spur I can't go smaller than a 21 or 22 pinion by the looks of it
I probably should've checked a bit more thoroughly before buying the gear

[Chrislong]

Originally Posted by B&H Racing

Chris - Any mods to fit a on a Losi Spur Gear ?

Yeh, I reemed out the hole to match the layshaft bushing. be careful to get it bang on central.

Ideally, we need layshafts turned down to suit the spur - know anybody with a lathe?

Chris

[Chrislong]

Originally Posted by bender

Yep, unfortunately I've just discovered that - with the 80t spur I can't go smaller than a 21 or 22 pinion by the looks of it
I probably should've checked a bit more thoroughly before buying the gear

What motor are you using, you may be undergeared? I wouldn't gear even my fastest 5.5 motor that low. Im gearing it on 78/23. but don't forget - we can change the idler gears and thats what I will do if I need to.

[jim76]

Originally Posted by Chrislong

Yeh, I reemed out the hole to match the layshaft bushing. be careful to get it bang on central.

Ideally, we need layshafts turned down to suit the spur - know anybody with a lathe?

Chris

My old man has a workshop full of them. I'm seeing him this weekend so may take my cat down to show him and see what he says. What size do you need them taking down to?

[discostu]

Originally Posted by bender

Now that there are a few of us running the SX at my local low-grip dirt track, we are finally starting to improve the car for Aussie conditions. My car was handling and jumping very well, with the rear shock mod fitted for the first time.

However, I'm still not convinced that its effect is that great, and I believe that the mods greatest grip improvement comes from the sweep of the drive shafts, rather than the ballast difference by having the shocks out the back.

I've done a few calculations and discovered that moving the shocks to the back is only moving around 2.5% of the mass back approx 6.7% and moves the wing back only 3.2%. How much this contributes to improving grip is debatable, especially as my own car was never really lacking in grip to start with.

The biggest improvement in my car has been the fitting of Tamiya shocks from the 501x, which certainly improved the cars handling over the bumps.

Next meeting I will be trying something else, running the shocks at the front of the arm again, but modifying the arms so that the wheelbase is reduced a further 2-3mm from the kit "short" position. This should result in a similar wheelbase and driveshaft sweep compared to reversing the arms, but still allows the shocks to be in their original locations.

The next step is to try and get the motor as far back as possible. I'm switching to the 80t spur for the next meeting but it would be better if Schumacher made down to a 75t spur I think, though perhaps it would be difficult to get the right ratios with some of the hotter mod motors.

i can see were your coming from with the percentages moving the shocks behind, have you calculated the diffrence in force that loads up the rear shocks under acceleration having extra mass at the rear when the car accelerates it should create more rear load thus better rear traction assuming the shocks are setup correctly and anti squat plus every thing else that contributes to setup but as like for like test it should genarate more rear traction.

stu rand

[mw02veg]

Originally Posted by Chrislong

Yeh, I reemed out the hole to match the layshaft bushing. be careful to get it bang on central.

Ideally, we need layshafts turned down to suit the spur - know anybody with a lathe?

Chris

Les Orbell from Mr'O' foams has turned grant's down so we can now fit associated spurs on.

[Chrislong]

Originally Posted by jim76

My old man has a workshop full of them. I'm seeing him this weekend so may take my cat down to show him and see what he says. What size do you need them taking down to?

I don't know sorry dude, the size of the hole on a AE or Losi spur if you have one to measure.

[MattADH]

As Mike Williams says, Dave Orbell (son of Mr O Foams) turned some down for a few of us and I still have a spare in my glove box! Not sure of size but I think Dave has done enough to do it from memory!

I am still using the original Schumacher spur gear that I got with the car without issue but have the option of using AE/TL spurs if necessary...