26 replies to this topic

[Oldskoolbaby]

Ive replced the bearing with good quality ones and the gears crack tested so they should be ok. The gearbox is not mated to the block yet and ive heard you can shot pen gears as well as rods and other components. Have you ever herd of this being done as i recall someone who was fetured in one of the mini mags had it done.

[TimS]

they will jammy, helical gears are stonger. they just loose more power due to the side loading forces created!

[Guess-Works.com]

Can someone please substantiate this "Stronger" theory to me.....

[dklawson]

Helical vs. straight. I've heard arguments both ways about strength. I'm more inclined to believe the helical are stronger than straight as the amount of tooth engaged at any time is higher with helical gears and therefore the load is carried by more teeth (more material to carry the shear load). However, I think it's pretty well documented by testing that the helical gears (by design) allow slip between the teeth as they drive each other. This causes axial forces in addition to the obvious frictional losses. The reason I've always heard for using straight cut gears was increased mechanical efficiency and elimination of axial loads.

As for shot-peening of parts. I would never do this to a gear. Shot-peening is firing metal balls against a surface to work harden it, leaving a ductile core beneath. That's fine for a connecting rod as nothing "works" on its surface. On a gear, you're talking about "dimpling" (on a microscopic level) all the teeth that mate with each other. If you thought straight cut gears were noisy before... just wait until you replace that nice precision ground tooth surface with crater marks.

It also sounds like you've built up the gearbox already. You' can't shot-peen anything once it's assembled.

[Oldskoolbaby]

Ye, Ive built the gearbox but havnt fit the drops as yet. It was these i was wonderin if i could do. As there are only 3 of them could i not some how polish them? It would sure be a good alternative to staight cut drops for the road. It may be a bit tedious though.

[duds100]

Ive got 126.4BHP@wheels@7500 on a 3.1 with sc/cr box + drops on 10"rims. It pulls 7500rpm in 1st and second very well, 3rd tails off so i change at about 6800 and 4th pulls well to 6500rpm, Ive had it pulling 7300 in fourth along side a saxo VTS which read 122mph.

Currently, with a x-pin diff, it does 1/4mile in 14.9sec @89mph so i`m only just getting into 4th.

I have a 3.6 final drive and a sailsbury sipper going in within the next two weeks as I feel that the current ratio is compromising acceleration too much for top end as the car does indeed have the same aerodynamics as my local village church.

[Oldskoolbaby]

What do you think yours does 0-60 approx. Ive got a 3.1 in the garage and a 3.6 so itll be nice to hear the results of your change. Was you out accelerating the Saxo? Ive got no idea of the results to expect but your motors knocking out roughly want Im looking at so itll help loads.

[duds100]

Well I was beatin The 200bhp Civic type Rs which were runnin 15.3ish with an induction kit n exhaust i think, its beats VTS's as they run about 15.6 with filter manifold n full stanles.

Civic type Rs r 0-60 in about 6.7sec

There was a Porsche boxter there last time which i saw run 14.9 all day long not sure what they r 0-60 but mines go to be around 6.0sec - 6.5sec. Should be sub 6 sec 0-60 with the LSD n 3.6 running sub 14.5sec 1/4s hopefully.

[Oldskoolbaby]

Sweet, nice to hear some solid figures. Its pushed me towards the 3.6 diff so thats what ill stick with. I only do 30mph around town anyway so itll mean ill be using the gearbox & diff to its full potensial. Does yours weigh alot!
Beating Porches off the line sounds good fun;) Do you recon an LSD will make it hard to drive on the road?

[duds100]

It weighs 540kgs is stripped out, fibreglass flipfront, inner wings cut back, rear pockets n seat overhang removed, buckets, carbon boot, polycarb windows so its pretty light.

Dunno if it would hold the porsche of the line as they are RWD but i can pull the same times as it on the 1/4 so who cares!

LSD takes a bit to get used to. Ive found the grip is phenominal but it makes the car kind of point n squirt, de-cedleration is stricky plus if you let of round a corner the backend will overtake you! But if you master it you can take corners much faster - even in the wet.

[Oldskoolbaby]

Ive read that the 1st boxters do about 6.3 to 60. I never realised how focused your car is. I can lift the back corners clear off the ground but you must be able to do the whole back end. I bet its a bit twitchy when your on the edge. Im just wondering whether a quafe diff mite be a bit easier to control as it doesnt use any plates.

[duds100]

Yeah if you take the boot off its bonnet pins you can lift the back clean off the floor! The gear type quafe diff is the dogs for the road apparently. Rod at SMMC has is re-building my diff as we speak and the shafts are on order, want to try and get to a RWYB day sometime in may n see how much i improve my figyres by. I`m just gona put a picture of my car on the show us yours section if you want 2 see it as its had a lick of paint, all beit not a great one as i did it myself!!!