lazer zxr for winter racer

[rob m]

Well im going to give my car its first outing at a meeting sunday, hope all goes well and my rear belt holds up, ive just added a bit of a tensioner mod but its not the best but fingers crossed it will work for the day.....welshy , how far off are you from completing your tensioner? Sounds like you have almost finished from reading the lazer thread.

[Welshy40]

Just bought the screws, bearings, nyloc nuts, now need the cf plates, washers and spacers and its for sale. Reckon two weeks and game on. Your designs ok but your limited as that bearing stops you using pinions and movement of motor. That believe it or not was my first tensioner design so nice attempt.

[rob m]

Well my lazer was put up against todays best 4wd cars and i was impressed, it kept the pace and i was taking it easy. I was also impressed with the one way system when i got the hang of it, even the original ball studs held fine . My quick diy tensioner did the trick as the rear belt held up but the bearings i used did get very hot! Really looking forward to my next race meeting.

Set up wise it seemed very good (thanks for advice welshey) but may give the ball diffs a try and maybe a zx top deck with belt cover to stiffen it up and see how it goes.

[Welshy40]

Well you could buy the cf tub as that stiffens it big time. I dont think the zx top deck will stiffen it, i think it give flex. Yes bearing gets hot and blocks motor movement but soon my design will be available. Youll find once its dialed youll be easily as quick if not quicker than the new cars

[terry.sc]

Originally Posted by rob m

Set up wise it seemed very good (thanks for advice welshey) but may give the ball diffs a try and maybe a zx top deck with belt cover to stiffen it up and see how it goes.

As James says, the ZX two piece top deck isn't a good idea. It does keep the chassis as stiff as the ZX-R setup, but only if it is run with the chassis spine that lock the gearboxes together. You are just adding more weight and making it harder to work on just for the sake of keeping dust out of the front belt.

As for snapping rear belts, I've never had that problem after running every week for 6-7 years on carpet. I snapped a few early on, when I tried drilling through the ZX centre diff and bolting it together, until I took the balls out and ran it as a slipper. Kept the roller guides on the layshaft as they do stop the belt skipping which damages the pulleys, leading to belt wear. Never had a problem with it running 10-12 turn brushed in it back then, just allow the slipper some movement. It can be tricky finding the sweet spot for the slipper to give under shock loads while still giving full drive, but you just have to adjust the nut by fractions of a turn until you get it right. Had it out again recently running with a 10.5T in it for racing and general bashing...


and still not damaged a belt. I don't think you need to worry too much about it. After all the belts are exactly the same as those in every other modern belt drive buggy.

[Welshy40]

Terry, the tensioner ive designed is based on my proto cf gearbox and is there if you feel the need to go for more power such as a 5.5 orr 6.5 and should handle it with no complication.

Im like you with a 10D i very rarely snapped a belt but brushless has so much torque the belts need a little tensioning to handle the power.

Also have you modded a car for touring car racing and if so what did you do with the shock towers?

[terry.sc]

Originally Posted by Welshy40

Also have you modded a car for touring car racing and if so what did you do with the shock towers?

My touring car chassis didn't have much that wasn't changed some way. Home made shock towers to run short front shocks all round and wider at the front to move the shocks further out on the Mid wishbones used. Bigger gearbox brace over motor. Home made top deck, it started life as a ZX. Optima wishbones and uprights. Gear diffs filled with Kilopoise grease, they moved easily when cornering but when one wheel slipped the grease would stiffen up to lock the diff. No minimum weight limit, so everything was cut off that could be removed. Pictures are rubbish as they were taken years ago.

[Welshy40]

Cheers Terry, ive built my chassis minus wishbones, shock towers and hubs. I see you kept the angle of the front shocks and less on the rear. Interesting so will be basing my design around yours. Wishbones im having a new set made.

[terry.sc]

Rear shock are mounted on the front of the arms purely because I'm using Optima arms, rather than choosing to mount them in front.

Using the Optima arms the shocks are mounted right out near the outer pivot, I would say around 10mm near the end of the arms so there is very little leverage and I could use standard Kyosho gold springs.

[Gayo]

Originally Posted by terry.sc

Gear diffs filled with Kilopoise grease, they moved easily when cornering but when one wheel slipped the grease would stiffen up to lock the diff.

That's interesting, wonder how would that work on a modern gear diff car.

[Welshy40]

Originally Posted by Gayo

That's interesting, wonder how would that work on a modern gear diff car.

I packed mine with vaseline (no jokes please ) in the 90's and worked great on high grip as well as medium grip. Won quite a few events with that.

[terry.sc]

Originally Posted by Gayo

That's interesting, wonder how would that work on a modern gear diff car.

Kilopoise grease is used for sliders and hand controls on machinery, where they need to be able to move easily at slow speeds but to add a damping action at faster speeds. It would be interesting to try, but it costs £80-90 for a small tub of it. I was lucky enough to know someone at the time who borrowed it from his work.

[rob m]

Im running a 6.5t brushless in mine which may of been the problem when i stripped the teeth off the rear belt, i could hear the belt jumping under acceleration. Adding the bearings as in picture above worked but now have no way of adjusting the tension if i need to. I am now on with trying another idea that will supply adjustable tension to both front and rear belts.

As for my top deck,i will stay with the zxr one, the gear zx diffs i will keep on using for less maintenance over the zxr ball diffs but try some grease or vaseline.

[Welshy40]

Originally Posted by rob m

Im running a 6.5t brushless in mine which may of been the problem when i stripped the teeth off the rear belt, i could hear the belt jumping under acceleration. Adding the bearings as in picture above worked but now have no way of adjusting the tension if i need to. I am now on with trying another idea that will supply adjustable tension to both front and rear belts.

As for my top deck,i will stay with the zxr one, the gear zx diffs i will keep on using for less maintenance over the zxr ball diffs but try some grease or vaseline.

Rob, wait a week or two, thats all and you can buy my tensioner. One tensioner only and ive based it on my cf gearbox design that i have been using and developing over the years. Its got plenty of adjustment sections so when the belt slackens you can adjust and tighten so giving more life to the belt. Its also not portruding so means you have no worries with gearing up as the motor wont be blocked.

[Welshy40]

Copied from page 214 where youll see pictures as unfortunately i couldnt copy. Pics show my proto cf plate with bits and pieces but have now refined it and just done a manual as well. Hope it help you make your mind up.

As promised here is my first tensioner design for the standard gearbox. Im going to get a plate made from fibrelyte and that should make life a bit easier but may need to cut a fraction more away from the gearbox for it to work correctly. Still its a start and feels set correctly.

Also ive moved it from my preferred position which I use on my prototype CF gearbox as of I used a similar position you cant use the full range of pinions as the tensioner gets in the way. This was it avoids the motor and tensions the belt correctly.

As always opinions are always welcome.
Attached Thumbnails

[rob m]

My idea for my tensioner has changed. first pic was my original idea, but now just a front tensioner. The rear was going to be like the front but running on the tension side with the idea that i could get more teeth to do the driving on the la11 pulley by having the belt wrapped around the pulley more but have decided it will create to much stress on the belt and pulley.
Pics of my idea and front pulley.

[Welshy40]

Ive already designed it all including the front tensioner so would recomend looking at my car pics on the zxr thread. Ive developed over years of testing so would save you time and money in developing by buying mine

[rob m]

It only took me 15mins to make and doesn't cost me anything as i make it all at work using the cnc and manual millers/lathes etc and off cuts.
Do you have any idea of a price for your rear tensioner ?

[Welshy40]

I didnt know you had that kindof talent, superb.

Yes if you study my chassis in the last couple of pages on the lazer zxr thread youll see my L brace tensioner for the mk1 chassi. Also the rear gearbox tensioner, ive taken my design from my zx cf gearbox and made it fit in the only place on the gearbox where it makes the tensioner work correctly. I cant explain properly as im in a hotel at the mo cleaning my car after a days racing but ive tried every concievable design and found the best suitable for this. I will post some pics next week to show you properly.

[Welshy40]

Rob as promised this is my proto but ones Im selling will look pretty much the same all depending on the colour of the washers. Its pretty simple but believe me ive tested every concievable method and this is the best, plus it doesnt stop motor movement so stock and modified gear ratios wont be affected. and also you can tighten the belt or losen meaning your not set to one particular tension setting especially when the belt stretches it comes in handy.