700R4 External Mod

[ssapach]

I have a project on the go and I may be running into a slight clearance issue with my transmission and front driveshaft.

My driveshaft may some up high enough to either gently rub or catastrophically smash into the pan of the 700R4.  It is a passenger side front output t-case so the area in question is the right-rear of the transmission (when sitting in the drivers seat facing forward).

I'm curious if I can trim that portion of the pan down a little bit for an extra bit of clearance or if there are some delicate pieces in that exact area that won't allow me to trim it at all?

For starters, I need to check my suspension up travel on the right front to make sure it will or will not touch the transmission.  I can also use a narrower diameter driveshaft than what is shown in the picture.

Here's a picture for a bit of a reference to the area I'm talking about.

[beastie_3]

what transfer case do you have? if the driveshaft travels straight up, how much clearance do you have? I dont see a driveshaft moving side to side, especially on a straight axle leaf spring setup.

[Grim 82]

What are you changing around that has led you to this conflict of time and space?

[ssapach]

Well for some added info:

Used to be a 1984 Toyota 4x4 pickup, with a 4.3 Chev and 700R4 bolted to the Toyota t-case.

I'm still using the Toyota t-case, the front and rear are no longer leaf sprung, but are a triangulated 4-link setup that will have coilovers or airshocks (undecided at the moment) so its not as rigid as the old leaf springs. 

Whether there is any side to side movement, as it lines up now, the driveshaft would still hit the transmission with enough up-travel of the front tires/axle.

I never had this problem in the truck form previous to this buggy project, but I have eliminated the extra reduction box I had in my drivetrain and I have also moved my engine/trans/t-case back about 8".  So previously, the front driveshaft had much more clearance, not to mention less suspension flex.

That being said, the problem is still in the end of the driveshaft that sees a lesser amount of movement during suspension flex.  So it may not be a problem, but thats something I would have to check out by flexing everything.  And if I do flex everything to the max and find out it has interference issues, it would be nice to be able to fix it with something as simple as a modification to the corner of the transmission pan.

[beastie_3]

ah. I wonder if a divorced T case would help. I dont know if trimming the pan and casing would lessen strength, as well as sealing capabilities.

[Grim 82]

You could clock the t-case. Post up some pics of this project. It sounds pretty cool.

[ssapach]

I appreciate the ideas, but I already have excuses to not want to go certain ways.

A divorced t-case (like NP205) would be much heavier, and would require a 2wd 700R4 and extra length because of an extra intermediate driveshaft.  If i'm adding extra length like that, i'd sooner just put the extra toyota reduction box back in place.  But i'm really trying to avoid it because then i run into more interference issues in other areas.

Clocking might work too, but it will cause my t-case front output to be lower, decreasing ground clearance and requiring modification to the cross member.  Not to mention the cost of a clocking ring would probably hurt a little.

So far my easiest and most affordable options would be to have a narrower drive shaft and/or trim the tranny pan.

This is one of those things that never occurred to me before it was too late, as I figured i never had this problem before.  Just failed to realize that extra 7" of reduction box makes a bit of a difference.

Here are a few pictures for your viewing pleasure.  I don't want to post too many, but maybe later when I'm closer to done I'll start a build thread in the correct area on the forum.  I'm a bit of time away from being mobile yet, if I would have really had a good idea of how much work and how long this was going to take me I would have left it as the pickup that it was.

Pickup that it was previously.....



Some rear links....



Front Links



And the mess that I left it off as before I left for work



I had a few more pictures between the suspension and the cage.....but they got lost when my previous computer died on me.

[Grim 82]

That's a cool build.

Have you fully flexed it to see how much clearance you will need? Is it just the flanges by the gasket that would interfere, or the bottom of the pan? I think you could get away with removing some material from the flange or dent the pan some if you needed to, but if a smaller diameter driveshaft will work that would be your best bet.

[ssapach]

I'm planning on using a square tube driveshaft, so no bigger than 2" square tube would be used.  I can also put the larger tube on the axle side of the driveshaft and save the narrow tube for the t-case end.

The issue on the transmission is the pan itself.  The driveshaft will hit the sump pan first.  My concern is that there is something important within the transmission at that exact spot that might not allow me to modify the pan at all.

And I've been busy with work and haven't been home much lately so I haven't gotten a chance to work on this thing much.  So I haven't flexed the front end yet either.