Engine and Transmission Tech

Will the TR-7/8 5-speed work well with the 215 Buick. Ran across one from a 4 cyl. that says will work on V8 swap but did not know if the ratios were right? Is it better to hold out for Camaro V8 5-speed....budget is strained.....trany does have the bell housing.

Bell housing from TR7 won't work w ith 8. Most folks want too much $$ for the V8 bell.
Glen should be able to say if the TR7 trans is same strength.
With three TR8 trans I had nothing but poor shifts even after $800 in new parts. Others like them though.i now use a new Ford T5 world class.

One of my buddies had a TR8 and like Mike said even after a lot of trans work it still didn't work well.
Dave

LT77 is the same in TR7 or TR8, but used different bell housing. TR8 engine is basically a 215. Mike Perkins will probably respond to you on this thread, as he is on here frequently, and he is an expert as is Todd Kishbach. There are some parts you need to get to make it work, and some work arounds. You may want to PM either one of those guys. They may not read the MG forum much since they are TR guys.

Dan B



Edited 1 time(s). Last edit at 08/23/2012 01:47PM by Dan B.

Quote:

They may not read the MG forum much since they are TR guys.

I guess this is what we have an engine-and-transmission section for...

I am running a TR7 box behind a 4,6 motor. The box came from a 2 liter version and is supposed to be the weakest of the lot. Later suffixed boxes are marginally (?) stronger. Anyway, years ago I just checked the internals, put in a new oil pump and have no had any issues. I am using ATF oil and it shifts just fine. OK, it can´t be compared to super smooth Japanese boxes.

Like already mentioned you need a V8 bellhousing, release bearing carrier and a pivot pin for release bearing fork as these are different on TR7 and TR8.

A bell housing is relatively easy to find, as is the pivot pin (available new from the UK), however the bearing carrier is fairly scarce. when I did my conversion, I modified the TR7 one I already had by extending it with an adaptor that I pressed on and brazed in place. Works great.

This is the adaptor I made:


TR7 (4 cyl) vs custom TR8 (v8) carrier:


TR7 & TR8 carrier dimensions:


Adaptor dimensions:

I have found that unless you have a low mileage or newer, 1981 TR7 box that with 90hp and same torque even with new fluid will or could be bad with the extra torque of a V8. The TR8 boxes that go bad are from bad 2nd and/or 3rd gear synchros or a pump failure. There is something strange that a TR7 box from the same year as a TR8 dont work as well in a TR8 and this could be a "from new use" between the 4 cylinder and the V8 break in. The choice to start from scratch would be a T5. Better gear ratio selections, common, simplified system of a hydraulic throw out bearing collar. What you will need for the TR7 gear box is a Rover V8 bell housing, pivot pin, throw out bearing collar, dust cover, and pilot bushing for the crank. The TR7 clutch arm, slave cylinder, pushrods and throw out bearing are the same as TR8 and rover SD1. The gear ratios are the same except the 1981 TR7 & TR8s have a .79:1 5th gear vs a .81:1.

I have never had a problem throwing trannys from 7s into 8s. The later trannies are slightly stronger than the 77/78 versions. This past Spring, I put a low mileage used one into a buddies TR8 which has a 4.0 putting out roughly 240HP. It works great. Check for input shaft play and replace the seals front and rear before you install. You can make the TR7 carrier and pivot work, but you have to put a shim washer under the pivot arm. Been a long time since I've had to do it, so I'm a little foggy on exactly what you have to do, but it can be done if you don't have the TR8 parts around. As an alternative, buying V8 bellhousings and clutch components off British Ebay can be a cheaper, easier way to find what you want.