Spike

Hi All

Like a number of people posting on this thread I've been modifying my Sakura with useful 3Racing hop ups e.g.steel front driveshafts and narrow rear wish bone mounts etc. All of which I've found to be well made, effective and cheap!

In an effort to replace the kit shocks with some better Kyosho TF5 ones I had laying about I replaced the kit front and rear shock towers with the +4mm ones. After I had fitted the +4mm rear tower I noticed that my right hand side wishbone looked higher than my left. I used a droop measuring tool to confirm my suspicions and it was just under 1mm higher. I checked my shock lengths and they were identical, I then swapped the shocks over and still the right hand side was higher.

To cut a long story short I checked every aspect on the rear of the car to ensure that it was straight and un-tweaked by swapping out used for new parts; in the back of my mind I had my doubts about the rear tower though. I finally proved it by watching carefully as I tightened up the screws that secure the tower to the rear alloy mounts. Sure enough as I tightened it up and the screws moved into the countersunk areas of the tower the right hand side wishbone moved upwards I flipped the shock tower over, so the countersunk areas faced in to the alloy mounts and used button head screws. As I tightened them up the left hand side wishbone was moved higher. Therefore the mounting holes must have been incorrectly machined into the tower

Anyway my question - has anyone else suffered from this? Or can I safely buy another tower and just console myself that it was a one off?

Thanks

DanDan

iTrader: (6)

Hi,

I do use the +4mm rear tower but do not have this issue.

The suspension arm blocks are separate to the bulkhead and tower, it should not affect the wishbone height even if you tighten up the shock tower, the only affect I can see would be left/right diff height, or dog bone blade is pushing against the diff outdrive, or bent bulkhead causing tweak, or even your sway bar

Try to take your dog bones out, tighten the tower and measure the wishbone height again, see how you go.

Also, make sure the damper length are more than 60mm from top to bottom

Hope these would help.

Spike

Hi DanDan

Thanks for the reply and suggestions. Sorry I should have made it clearer which parts I was referring to. The "rear alloy mounts" I mentioned was the rear bulkhead assembly

I have tried assembling it without the dog bones and it was still out by nearly 1mm. My shocks are 61.5mm from end to end.

Looks like it's time to hit RCMarket for another tower

cheapskate.brok

iTrader: (10)

take out the setscrew in the arm (the one that afftects droop) and see if the same problem persists.

The Teacher

iTrader: (62)

Spike, with the shocks off of the rear of the car do the arms fall free down to the chassis? When you measure the rear droop without the shocks on the car is it even? Could you possibly have a bent rear bulkhead? If all of these things are good I would say it's the shock tower. However, I have several of these towers and don't see any issue with any of them. Maybe you just got a bad one....it's possible...

Spike

Thanks for the suggestions Cheapskate.brok and Teacher


1) With the shocks off the arms fall freely towards the chassis and the droop is identical. The rear bulkheads are the only parts I haven't tried replacing. I could borrow my mates' Sakura for the parts (he's given up on it because it was such a painful experience to get a decent setup). I'll try swapping them and re-post.

2) I tried removing the droop screws from the arms but it made no difference

I feel reassured that no one else has had a similar problem with the towers.

InspGadgt

If he flipped the shock tower around and the problem moved from one side to the other (like he stated it did), then the problem is not in set screws, shock lengths, bent bulk heads, or binding suspension. It is the shock tower.

The Teacher

iTrader: (62)

InspGadgt, never hurts to check those things anyway...

jeff_78

hi..
my sakura's driveline has been causing me alot of greif. The replacement rear belts kept snapping after just a few laps. When i increased belt tension (1 increment) it melted the white plastic pulley.

The pulleys seem to slide off the pink alloy carrier and push the large alu washer and spacer against the bulkhead which causes alot of friction.

I dont see any point in having the pink aluminium washer. It appears to be a retainer for the pulleys, but it will push the spacer against the bulkhead if it performs this function.

i had the standard screwless spur adapator but now ive installed the new one with screws (SAK-U05). Ill have to wait for next race day to test it.

With better alignment on the pulleys i think there would be less load or tearing action on the belt so im hoping that will fix it.
Ive also removed the pink aluminium washers, replaced by small spacers which make contact only with the inner ring of the bearings.

Has anyone else had belt troubles and fixed by the new spur adaptor?

dameetz

I run 2 Sakuras, 1 for mod and the other for boosted stock class and I have never had any problem like yours. I m also still using the original screw less adaptor. I put mine just like from the instruction manual and add some more 0.1mm spacers to reduce the side to side play and I m using Tamiya 105t spur gear which I think is a little bit thick, if thats make any difference.

jeff_78

i have a gear diff... problems didnt really begin untill i fitted that.
but it should be able to run it reliably.
the original kit belt lasted alot longer with gear diff than MBL replacements though. but eventually (maybe 4 races) it did strip...the mbl ones snapped very quickly (a few laps).
fingers crossed for the new spur adaptor.

thanks

DanDan

iTrader: (6)

Hi Jeff,

for the gear diff, are you running 37t or 38t?

I found the 37t do not fit well with the belt, if 37t in use I will suggest to use the 38t instead.

squarehead

iTrader: (75)

If they don't fit well, then what's the point of having that tuning option? For the spec classes here, it's really helpful to be able to use a 37t/21t combo. What exactly is the problem with the 37t pulleys? Too much slack in the belt? Not enough?

Sounds like the belt tension wasn't set correctly one way or the other. They make a belt tensioner for the front belt. You should be able to get proper tension no matter what pulley setup you are using.

martynp

I have been running my rear belt now for 6 months with no sign of real wear. I run in 13.5 boosted, up untill a few meetings ago running the kit ball diff now the gear diff with 38 gear as I dont have the 21s. I am using the kit spur set up. I have run the car both in and outdoors.

MICHAEL BROWN

iTrader: (8)

Sounds like the same issue I found, the belt starts to ramp up , to the next pulley tooth along - causes binding in the driveline.....
Switch back to 38t and the problem disappears ???