37,s on 75

[rockcrawler31]

Hi all.

after doing the chop on the old girl i am building up the rest of the truck and wondering whether i am likely to blow cv's in the 75 front if i run a locked diff and 37's.

also what kind of driving style and tips will minimise my chances of blowing a cv and how much are longfields for my truck.

also, what is the best size tyre to be eligible for most weekend warrior style of competitions?

MILO

[DNA Off Road]

Hey Milo

Yes you will break CVs if you drive it hard with 37s. If it is a later model cruiser with the high pinion centre, you may also break the crown wheel and/or pinion, depending on your driving style and what you call hard. To minimise breakage:

1. Drive more conservatively
2. Avoid coming down heavy on the front with heaps of wheel spin
3. Drive more conservatively
4. If you have the high pinion centre, hard driving in reverse [especially uphill] with the locker in will kill the centre relatively easily.
5. Drive more conservatively
6. Replace the original CVs with quality treated ones [if you don’t I suggest your carry spares and learn how to change them].

Note: If you change your CVs to quality treated ones, the next weakness is likely to be the axles breaking at the circlip groove. If you upgrade your axles, you may have troubles with your Free Wheeling Hub studs [you can upgrade these to 10mm vice the original 8mm]. There are a couple of threads on here detailing this and how to fix it.

I’m not saying you will have all of these breakages; in fact the 75 can take a reasonable amount of punishment as long as you are realistic. It is fair to say that your opinion of what is hard might be medium to an extreme sort of guy or vice versa. I suggest you keep wheeling with what you have now, carry spares and if you start breaking CVs and the like, upgrade from that point rather than spending a heap of time and money on stuff you may not need.

You can buy direct from Bobby Long at http://longfieldsuperaxles.com/ I don’t think they make an axle for the 75. There are numerous local Aussie guys that treat CVs such as CORE, Haultech and YURI.

As for the best tyre size, well that is a very broad question. It depends on the style of comp, however as a generalisation, most weekend style comps are limited to 36â€

[dogbreath_48]

I broke 2 on the weekend.

1. Doing a 3 point turn on top of a grassy hill - hardly any lock, very gentle (in reverse).
2. Just off idle in reverse getting winched out of a bog hole (i think the tyre picked up a log/rock).

I think the 2nd one was a dodgy CV in the first place though. If i hadn't had the front locked (not an option with a detroit) I wouldn't have broken either.

Having said that i only broke 1 with 34" JT's and that was copping some serious high-traction-bouncing-in-reverse abuse.

I'm on the lookout for an ARB front (want one anyway) then if that doesn't help the CV problem i'll give the haultech CV's a go.

-Stu

[rockcrawler31]

thanks heaps for that. I guess my idea of hard would be The claw track, carnage canyon, airlocker ave at cruiser park, waterfall track at ormeau etc.

So let's see if i sum this up right,

1. don't come down hard on a spinning front wheel
2. don't use reverse real hard
3. don't engage front locker when turning and driving hard simultaneously.

got any links for the 10mm front stud upgrade? I've seen links for the rear, i was going to use 10mm high tensile bolts instead of countersinking the rear axle flange. It appears to me that countersinking for 10mm bolts and cone washers doesn't leave a lot of meat.