driveshaft angle question

I've got just the opposite concern as a previous poster: I've got a potential issue with my bell housing (289/upright ZF) being too low. I'm aware that raising the engine will increase U-joint wear, and the CV coupling has restrictions as well, but are there other factors that limit the safe angle of the driveshaft as long as there aren't any suspension interferences at full travel? Increasing the wheel diameter isn't an option, and a skid plate is about the only alternative I have.
 
John,

You can increase the standing/static angle of the CVs (ie raising the car....) if you also limit the max droop angle. In other words, all you have to worry about as far as CV angle is to not exceed the maximum at full suspension load/unload. Obviously, it's best not to be close to the limit in normal operation as well...so it's a bit more sophisticated than just not exceeding the maximum.

What CV's do you have? The CVs from a 930 porsche (108mm) have a greater maximum angle than most other CVs....25 degrees. If you're using other/smaller CV's you might consider a switch to 930 CVs. Use Lobro's...not a cheaper alternative....the Lobro's are the ones to have. The 930 CV's use a 28 spline axle shaft.

Just my $.02.

Some background info: http://blindchickenracing.com/How_to/CVJoints_Axles/cv_joints_101.htm
 
John, I am running 930CV's on the 5000 at 12deg static with about 15 deg at full bump, and have not seen any problems to date, ie 1 season.
cheers John
 
The flywheel should be 13" dia., so you can place the engine so the crankshaft is 6.5" above the bottom of the chassis, use an appropriate oil pan and remain above the bottom of the frame if you cut off the bottom portion of the bell housing that would be below it, being aluminum is much easier than steel I would assume.
 
I worried for a long time about driveshaft angles prematurely wearing CV joints until I realised that with the low mileage I'm likely to do that even if they see a fraction of their normal expected life they're still going to last for years.

I mean most are going to be designed to last 120k+, so what if they only last 20k, I expect to do ~2k/year, that's 10 years use!
 
Dougs car is a Lotus 47 with an early 'O' ZF. Other pics of engine/trans assy's similar to his show a wet sump that suggests a 'nose up' engine installation angle ( Lotus 30 pics ), also IIRC the flywheel dia will be similar to early GT40 cars ( Smaller than 289 OE ), therefore I wonder if simply raising the front of the engine would alleviate his bell housing height concerns.
 
I've got an Aviaid dry sump pan 5-1/25" deep, and the flywheel is 160 teeth, about 11-3/4" dia. , so the bottom of the chassis tubes, the pan, and the flywheel are all essentially at the same level, with the bellhousing an inch or so lower. I'll post a sketch tomorrow that makes that a bit clearer. The scan of the bellhousing gives an idea of its configuration.
 

Attachments

  • bell rendering.jpg
    bell rendering.jpg
    46.1 KB · Views: 223

Chris Kouba

Supporter
John, I am running 930CV's on the 5000 at 12deg static with about 15 deg at full bump, and have not seen any problems to date, ie 1 season.
cheers John

John,

What boots are you using? I have about the same specs as you and can't seem to get a set to last more than a couple hundred miles.

Chris
 
That is the one problem I havnt solved as yet Chriss, ive split two outer boots in a year, so cant really complain that much apart from the mess that happens with bloody CV grease everywhere.

john
 

Chris Kouba

Supporter
That is the one problem I havnt solved as yet Chriss, ive split two outer boots in a year, so cant really complain that much apart from the mess that happens with bloody CV grease everywhere.

john

Aw crap- so your "no issues so far" meant just with cv angles, not a boot thing? I was really hoping you had it sussed. I do feel your pain on the grease everywhere issue.

I'll let you know where I end up when I start digging through it.
 
I've read that putting cable ties around the boots (in the bottom of the "V"s) can help the durabilty, but have no personal experience yet.

Cheers

Fred W B
 
Back
Top