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I need engine help+differential advice (BRAT)

Featured Replies

Hello,

 

I am trying to put together a big project. I have a beat to heck BRAT (1976 model year) and I want to put its chassis under a VW beetle (AWD beetle).

 

This BRAT has the EA-71, and only a single range 4wd transmission (not a dual range high and low gear). I was told that to get that transmission with the high and low range, I would need an EA-81 engine, because the bell housings were different.

 

My question is: Is it possible to switch bellhousings on the two motors? If not, is there an adapter plate available? (Because I already have the EA71 engine, it'd be cheaper for me to rebuild it rather than buying a junk EA81)

 

Also, I would really like a LSD differential, and from a thread on this forum, it looks like many of the Subaru differentials remained the same for many years. My other question is for the T71W 4WD transmission, how hard is it to find a LSD differential?

 

The rear differential is an old Datsun unit, and I cannot find anything for it.

 

If anyone wants to sell their LSD differential, or dual range 4wd 4 speed, I'm interested.

 

 

 

I really appreciate any help on this, it is something I really want to do!

First thing first... do you plan on keeping this a rear engine bug? If so, how do you plan on getting the tires to spin in the correct direction.

 

Second. If you are looking for a LSD for the transmission itself, you have two choices:

Spend about a whole TON of money on R&D

or

Stop looking cause they don't exist.

 

If you want a LSD for the rear diff, they are out there. However, if you're keeping this a rear engine vehicle, your rear diff will now be your front diff and a LSD up front isnt a good idea.

  • Author
First thing first... do you plan on keeping this a rear engine bug? If so, how do you plan on getting the tires to spin in the correct direction.

 

Second. If you are looking for a LSD for the transmission itself, you have two choices:

Spend about a whole TON of money on R&D

or

Stop looking cause they don't exist.

 

If you want a LSD for the rear diff, they are out there. However, if you're keeping this a rear engine vehicle, your rear diff will now be your front diff and a LSD up front isnt a good idea.

 

What I think would be best is if I kept the BRAT config, with the engine up front. Putting the VW pan on a modified BRAT pan/chassis. I could always use the rear engine compartment of the VW as a trunk, plus I will have some sort of rack on top for storage.

 

You are right about the front vs rear differential. You said no locking or lsd exists for the T71W trans? That's too bad. I have had no luck with finding anything for the rear Datsun IRS differential.

 

There is a mechanical E brake locking system in the front, so I will manually route each brake side to a different lever, effectively giving me a "manual" locking differential by pulling the lever of the spinning wheel. That is good enough for me failing everything else.

 

I could probably engineer a locking pin system for the differentials, however it would likely not be a long lasting solution.

 

Are you aware of a transmission adapter plate for the T71W to be mated to the EA71 engine? I'd like to use the EA-71 motor with the dual rang e 4x4 transmission. Do you have any pictures of the exact difference between the two bell housings?

 

 

 

Here are the pics, although I'm sure you really don;t want to see them! The whole reason behind the VW cab swap is because the BRAT is so trashed.. It has been sitting in the harsh desert for 20 years!

 

http://img.photobucket.com/albums/v237/wolfmangk/0309091212.jpg

 

http://img.photobucket.com/albums/v237/wolfmangk/0309091212a.jpg

 

http://img.photobucket.com/albums/v237/wolfmangk/0309091213a.jpg

 

http://img.photobucket.com/albums/v237/wolfmangk/0309091213.jpg

 

http://img.photobucket.com/albums/v237/wolfmangk/0309091213b.jpg

 

http://img.photobucket.com/albums/v237/wolfmangk/0309091213c.jpg

Edited by tundrawolf

I do not know of any adapter.

 

The two major differences are the bell housing and where the starter mounts.

 

Dual range transmissions have the starter mounted on the drivers side of the transmission, whereas single range 1600cc transmissions have them mounted in the center. Ofcourse, the bellhousing for the motors must match the transmission. In all honesty, it wouldn't be much more expensive to find a parts car from 1981 to 1984 and get the engine/trans from that. But i understand where you are comming from, having the parts from the '76 and all.

 

Is locking diffs & Dual range truely necessary?? Are you going to be wheeling this thing or just rallying it?

 

Rear LSD's exist. Matching them to the transmission's ratio is the only problem.

  • Author
I do not know of any adapter.

 

The two major differences are the bell housing and where the starter mounts.

 

Dual range transmissions have the starter mounted on the drivers side of the transmission, whereas single range 1600cc transmissions have them mounted in the center. Ofcourse, the bellhousing for the motors must match the transmission. In all honesty, it wouldn't be much more expensive to find a parts car from 1981 to 1984 and get the engine/trans from that. But i understand where you are comming from, having the parts from the '76 and all.

 

Is locking diffs & Dual range truely necessary?? Are you going to be wheeling this thing or just rallying it?

 

Rear LSD's exist. Matching them to the transmission's ratio is the only problem.

 

Thank you for that reply. It does help me. I have looked pretty hard, and have not found anything on any sort of adapter plate.

 

Locking diffs would be a big help, as I plan to really offroad it, and have needed it badly in the past. Dual range is something I can't live without, living here in the desert with some pretty nice trails.

 

Let me ask you this... Is the single-range 4 speed transmission the same length as the dual range? I ask because I could put this together with what I have now, and do a simple engine/tranny swap, if all the dimensions are the same, later, pretty quickly.

 

Any resources for the EA81 and dual range transmission? I have had very little luck..

 

 

 

Edit: There's just no way around it, I need the EA81 and dual range tranny. The EA71 motor I have needs to be rebuilt pretty bad, and the tranny isn't much better.

Edited by tundrawolf

An adapter plate wont help you much because it wont change the location of the starter.

 

For more answers toward your locking diff question, I would recommend you check out the off-road forum. The guys there have been throwing around idea's for locking front diffs, but none of them are cost effective.

 

If I remember correctly, the single range & dual range tranny's are the same length. I have heard of people converting to dual range without needing to change their drivelines.

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