Cat 2000 - Gear Ratios etc??

[Nick Goodall]

Well i'm going to try and race the car this weekend at the Stotfold 4wd Regional, but i need some help with gearing......

Last night i went through the old book and on a 12 turn they suggest a 95 Spur with 17 pinion so i thought as i'll be running a 12 turn Checkpoint, 3300's and 3800's i'd go up two to a 19 but the car still seemed a tad under-geared, certainly sounded it.

Should i just go to a 20 pinion?

Also, the rear diff was extremely stiff after one run of practise so i'm a bit worried about that - Pidge suggested loosening it up a bit but i'm not sure that's all it needs..... i think this could explain why it got quite hot too?

Anyone have any other suggestions with gearing on todays motors and batteries?

[Southwell]

I 'think' i used to run a 19/92 with a 11 so 20/21 should be better.

If the diff is getting hot i would rebuild it, turn the diff rings and thrust rings over and then set, it should be a lot better. Thats all i did with your B3 diff.

[chrispattinson]

Your current ratio
Motor 12x2
Recommended ratio 9.5
Spur 95
Pinion 17
Internal ratio 2
Final drive 11.18



Suggested
Motor 12x2
Recommended ratio 9.5
Spur 95
Pinion 20
Internal ratio 2
Final drive 9.50




My ratio
Motor 4.5 brushless
Recommended ratio 12.5
Spur 93
Pinion 17
Internal ratio 2
Final drive 10.94

[chrispattinson]

My biggest problem at the Bury regional was getting the back of the car to stay in contact with the ground, couldnt get it to absorb the bumps. I was getting there with AE number 1 pistons, 30wt oil and yellow springs on the rear.

Might go to shorter wheelbase to get more weight over the rear, or some weights on the back. Any suggestions are welcome.

Other wise it was great, very fast. Q4 I made 17th in round, which wasnt bad as my heat had a wet run, and I was only getting bottom of the B, top of the C with the X-5 last season.

Hoping for better things this weekend at the North East 4WD regional at Nissan.

[Nick Goodall]

Cheers guys,

I'll try a 20/95 and see what that's like, maybe even drop to a 92 spur....

Ian, i'll also give that a go with the Diff, i'm hoping the plates haven't already been turned round too....... but it feels very stiff and crunchy, hopefully i can get rid of that.

I'm running Associated shocks all round, but had to go to No3 Pistons with 40wt front and 35wt rear as it just felt too soft with 2's and 1's respectively. That was with Blue front springs and Silver rears, i also put losi ball ends at the bottom of the rear shocks to create a bit more droop as there's nowhere near enough with the standard set-up, i also moved the front shocks to the inner hole on the wishbone to do the same.

It went ok round CML Raceway ok with this set-up, was maybe a tad soft at the rear according to Lee so i was going to go to 40wt all round. My main thing is going to be the rear diff and getting the gear ratio's right.

Fingers crossed but i'll let you know how it goes!

[chrispattinson]

Nick,

wow, maybe Im going too soft then if you've been advised to go with heavy oil, I was thinking I may have to drop to 25???

Are the blue front springs AE or schumacher?

[niggs98]

if you have used both sides of the plates nick u can always refurb them with some fine wet n dry on a flat board to keep them square

Originally Posted by Nick Goodall

Cheers guys,

I'll try a 20/95 and see what that's like, maybe even drop to a 92 spur....

Ian, i'll also give that a go with the Diff, i'm hoping the plates haven't already been turned round too....... but it feels very stiff and crunchy, hopefully i can get rid of that.

I'm running Associated shocks all round, but had to go to No3 Pistons with 40wt front and 35wt rear as it just felt too soft with 2's and 1's respectively. That was with Blue front springs and Silver rears, i also put losi ball ends at the bottom of the rear shocks to create a bit more droop as there's nowhere near enough with the standard set-up, i also moved the front shocks to the inner hole on the wishbone to do the same.

It went ok round CML Raceway ok with this set-up, was maybe a tad soft at the rear according to Lee so i was going to go to 40wt all round. My main thing is going to be the rear diff and getting the gear ratio's right.

Fingers crossed but i'll let you know how it goes!

[Nick Goodall]

Originally Posted by chrispattinson

Nick,

wow, maybe Im going too soft then if you've been advised to go with heavy oil, I was thinking I may have to drop to 25???

Are the blue front springs AE or schumacher?

Chris, that is with Associated shocks though, or are you running them too?? I was running associated springs (blue front, silver rear) but am going to go to 40wt all round and possibly a green spring on the rear.

I just hope i can get the diffs sorted as the car should be fine then! Seemed good round CML to be honest

[chrispattinson]

The wet and dry trick on the diff plates should work fine.

While you are in the diffs, put a new nylock nut in to replace the old one, as once the diffs start to 'adjust' themselves durring a run, it is an indication that the nyloc may need replacing.

Also, make sure the allen head of the diff bolt is on the correct side (the left of the car I believe).

[MattW]

Nick, i'm thinking you're WAY undergeared!!! A couple of years ago when i was still running the 3000 (same transmission parts/ratio) i was running 10 turn on 20-21/87.

So i'd be up a couple from that for a 12 turn!!