MGB Gearbox whine

[chodjinn]

I am inclined to agree with Ian on this one. Not from experience or what I have read on the t'internet, but from common sense really (I'm usually short of that).

The way I figure it the 'word on the street' is that an LT77 will take circa 250bhp . . . but that is based on an SD1 which is waaay heavier than the little MGB (by the way, I have one).

Now the kerbweight of an MGB is roughly 940kg. The RV8 is roughly the same weight as the original B series. Now my car has all of the interior stripped, including all those damn heavy wooden window/door cappings, plus a full sebring kit, lightweight seats. I figure I'm well under 900kgs now.

Compare that to the kerb wieght of an SD1; 1335kg, that's over 400kgs difference. Therefore it'll take less force to get the 'B shifting, putting less strain on the gearbox. From a few people I've talked to an Lt77 should be good for well over 300bhp, more like 350+. Well I hope so anyway!

As for the R380s, yeah there does seem to be this 'better than Lt77' stuff, but as stated already by someone they are expensive and hard to get hold of.

Please correct me if I'm wrong tho . . .

[mgbv8]

Fitting the TH350 as an alternative to a manual box on an MG V8 conversion, is easier than fitting a manual box. The adaptor kits is readily available, there is very little to do on the tunnel, the gearbox cross member can be made with a bit of decent channel iron. Mine was already a factory V8 that I was converting to auto, and guess what. The gearbox mount lines up exactly with the original cross member mounts.
So to fit the gearbox mount was a bit of channel iron with 6 holes drilled in it.
The prop is easy and there is no real hassle fitting the shifter. I actually opened up the top of the tunnel and sunk the shifter 3" into the tunnel.

Obviously the gearbox isnt cheap to buy new. But when I did the research I opted for the auto to make the job easier. Plus I wanted to use the auto for racing.

[JC.]

Theres no problem withe the TH350, its been about for years.
Back to the original post, Noisy gearbox, Normally once the noise is noticable, tne damage is done, you could try EP90, which is thicker and may quieten the noise and make it drivable. 20/50 seems a strange choice for a gearbox it has no pressure addatives to maintain the oil. thats what the EP stands for, Extra Pressure,
Now heres a question for the MGB owners, why do MGB owners who have converted to V8s have a fixation on using the the R380, They are EXPENSIVE, Hard to find and easily confused with its older brother the LT77, I would be using the LT77, there are plenty of people on this site using LT77s and giving them SERIOUS abuse, the Axle will give out before you break the gearbox, and MGBs have issues with getting plenty of sticky rubber under the arches, so you have a safety valve built into the system to protect the axle and gearbox, Fit a LT77 its cheaper, you wont break it, especially if you have been using a MGB 4 speed, I think the old P5 boxes were based atound the B box, and Nobody will use one of those cos they are fragile.
Ian

I know there are no problems as such with the TH350. It was a private comment between perry and I... although since he didnt comment perhapse I struck a nerve. Sorry mate

As for why fit a R380 instead of an LT77?
Roger Parker says so. n' thats good enough for us MGOC folk

Taken from a post he left for us last year....

"For many years I have seen the use of both LT77 (SD1) and the R380 gearboxes in V8 conversiChanged the gearbox in the V8 just over a week ago from LT77 to R380 and yes it can be done but dropping the engine out from underneath. Took less than two hours to drop the LT77 out.

The R380 is a direct fit in place of the LT77 and uses all the LT77 parts, which some caveats.

My conversion, based on a 1968 that I did well over twenty years ago was converted to accomodate the LT77 gearbox. When I started the last series of changes involving a full strip down, changing the injection from airflow meter to Hot Wire, and a number of other changes. The original gearbox I fitted was a used one, quite sound when it went in but by 1994 had weak synchro on 2nd and third.

An opportunity to obtain a new new ex Lucas test gearbox was taken and whilst a risk due to an unknown internal condition worth a risk due to cost. The gearbox worked great other than it had zero synchro on third. Ce la vie.

Having lived with this for some time I decided to bite the bullet and buy a new R380. Based on well versed information the change should be smooth as all ancillaries on an LT77 fit on the R380.

Yes this is true but fitting is not quite the same and it starts with the gearbox being tighter to get back in. Less than two hours to drop the LT77 out from underneath but getting the R380 in needed it to be lifted in sideways, fiddle the first motion shaft into the clutch hole, start to engage and turn. It took a while to get this just right! Then you fiddle fit the remote housing back on as this has to be removed to get it past the fixed body crossmember.

The real pain was the gearbox mountings are a good 20mm further back than the LT77 position. As my gearbox crossmember is a modified MGB one with a view to fitting to the last pair of captive holes in the chassis rails the different position meant the crossmember no longer fitted and needed to be moved rearwards. The crossmember also needed further mods as the rear housing of the R380 is much bulkier than LT77 and so extends closer to the crossmember.

The now modded crossmember was now connected to the gearbox and it was poisitioned and new mounting holes drilled. That now dictated dislodging the two internal steel blocks that provide the fixing threads for the crossmember bolts, drilling out the rear spot welds of the internal cage that holds this steel bar so that it could be moved rearwards to line up the new holes and threaded holes in the bars. Move gearbox out of the way and bolt these bars in position to allow a couple of small holes to be drilled to fit self tappers. This holds the bars in place so when struggling to get the gearbox bolted to the chassis losing the bars is not going to occur.

OK box in, prop connected etc as they all fit as before. Now shut garage door and go and have a good soak. The time elapsed had now exceeded over 8 hours and was agter six pm.

Fresh start following day. Go to fit my carefully created for the LT77 modified gear lever. Sod it - the remote places the lever position another 10mm furthe back, enough to create a conflict in the 2nd, 4th and revers positions. More mods later and the lever now comes out of the middle of the hole.

Everything else fits in the same way/position as on the LT77 as expected, but I have to say whilst I wasn't expecting this to be a perfectly straight forward job, I wasn't expecting the depth of hassle.

Nice having synchro on third gear though!

Rog"

[Alley Kat]

All I can say re the LT77 is, my Victor has had one in for 11 years. Motor was a healthy 3.9, 230-240hp. In that time its done a lot of miles with plenty of 'enthusiastic' use with no probs at all. Can't say the same for clutches though... Car weight is very much the same as B weights given on't web, at 2250lbs.

[ian.stewart]

Theres no problem withe the TH350, its been about for years.
Back to the original post, Noisy gearbox, Normally once the noise is noticable, tne damage is done, you could try EP90, which is thicker and may quieten the noise and make it drivable. 20/50 seems a strange choice for a gearbox it has no pressure addatives to maintain the oil. thats what the EP stands for, Extra Pressure,
Now heres a question for the MGB owners, why do MGB owners who have converted to V8s have a fixation on using the the R380, They are EXPENSIVE, Hard to find and easily confused with its older brother the LT77, I would be using the LT77, there are plenty of people on this site using LT77s and giving them SERIOUS abuse, the Axle will give out before you break the gearbox, and MGBs have issues with getting plenty of sticky rubber under the arches, so you have a safety valve built into the system to protect the axle and gearbox, Fit a LT77 its cheaper, you wont break it, especially if you have been using a MGB 4 speed, I think the old P5 boxes were based atound the B box, and Nobody will use one of those cos they are fragile.
Ian

I know there are no problems as such with the TH350. It was a private comment between perry and I... although since he didnt comment perhapse I struck a nerve. Sorry mate

"

No worries mate, no sense, no feeling

[mgbv8]

Ha Ha!!
JC is referring to my warranty grief with TCI over the new TH350 shredding its sprag on a shopping trip to Tesco. I had only done 400 miles when it gave up. It was a very long and protracted battle but Real Steel held out for me and I ended up with the box repaired under warranty and uprated (so they say) to a 700hp sprag clutch. I dont know if thats really something good as the rest of the box is only supposed to do 450hp. But tis torqe that shags yer box innit. TCI dont actually say what these things will handle, torque wise!!
The repaired box is still in the packaging from TCI as I had to buy a new one to get the car on the road.

[kiwicar]

Hi
I think the fixation with the R380 box is from the Range Rover boys, it is a common upgrade for a manual lt77 to the Satana version of the R380 box which is meant to have much stronger internals, however it has a tail housing for the 4x4 transfer box on the end of it. From what I remember this box is meant to be alot stronger than the LT77, however it is not meant to be the same as the UK version of the R380 (it was also made/used under liecence in the 6x6 Perentie). This is just what I remember from my days as a range rover owner and reading alot of 4x4 magazines. I await to be shot down
Mike