rcutclif's 1974 MGB-GT

Progress has been slow, but I got this mount ground down mostly. Very annoying to the the angle grinder down in there.

Big day today.

Clean steering rack wants you to know it is "ok" through all this.

I also ground down the driver side b series engine mount remains. Then I bolted up the RB crossmember and fit the engine. 

Wow! So much better.

I got the engine sitting basically exactly where I want it. Centered front and back, and level to the car. I still need to finalize the inclination of the drivetrain to match the pinion angle.

Here's what carl was saying the hole in the tunnel is offset toward the driver side by about 1 inch.

Here are some more photos of the fit. Plenty of space everywhere.

Note the stock trans crossmember upside down temporarily. Also, the parts lot is already paying off. Apparently I lost the trans crossmember bolts. And mg uses fine pitch threads on everything. But I had 3 in the parts lot! Score!

Next up, the engine mounts. I plan to go straight to the frame rail. Should be simple and strong, and will be welded in.

Ground down the areas I plan to weld my new motor mounts to.

But wait, what the heck happened here on the passenger side? I don't think this car was crashed, though 74-03 was a long time for something to happen. It almost looks like the car fell on something or maybe hit something on the road? Any guesses?

Also, my new motor mounts came in, so I cleaned up the metal parts and bolted em up. Nice.

Finally, I started working on the driver's side piece, and it's almost done. I thought I could get by without the cad, and I might actually pull it off, but now looking back I would've saved time with some paper templates.

Probably somebody clumsy/stupid with a lift, or it got dropped at the dock when it was new.

Sorry if this has been addressed but using the RB crossmembet effectively gives you a 1.5 inch body lift. I read you wanna drive the crap outa this so it needs to handle, and with the increased height of the RB crossmember, how are you going to address the handling issues?  Lowering springs will just increase the chance of bump steer and it will also decrease suspension travel, both things are not great for ride and handling....Again sorry if i missed the solution for that...but?

Well, looking at both right next to each other it's a 1 inch body lift, so there's 33% of the solution...

But really remember that handling is a relative term. Even the cb b is not going to hang with an NC miata. This is going to be a street car for me with autox and rallyx occasionally. I've got a competition car already and this one isn't that so I'm not worried about eeeking the last few percentage points of handling out. What competition would an mgb gt be winning these days anyway?

So, I'll currently plan to use cb springs in the RB crossmember and see where that lands me. I'm confident the miata engine is significantly lighter than the original lump too, so I was planning to address ride height with springs somewhere down the line. Yes I know that means less travel before the bump stops and that isn't ideal, but there are a lot of things "not ideal" about LBC suspension to begin with.

I guess then, that the short answer is "I'll deal with it later". Haha.

I'll be in the same boat in regards to springs, my set up should be around 90 lbs lighter than stock, so shorter springs will be something I'll be ordering.  But as far as lowering the car with the RB crossmember, have you looked into dropped spindles?  There are a few guys making them for the race car crowd (one example: dropped spindle ), it may help in the bump steer/bump stop/ roll center issues.

Id keep springs around,  and trim coils as necessary. I bet you will be able to dial in the height,  adjust bumpstops, and be in a "good enough for the application " place for just a bit of time. And cutting coils increases rate a little, so it may ride better just due to that.

RoddyMac17 said:

I'll be in the same boat in regards to springs, my set up should be around 90 lbs lighter than stock, so shorter springs will be something I'll be ordering.  But as far as lowering the car with the RB crossmember, have you looked into dropped spindles?  There are a few guys making them for the race car crowd (one example: dropped spindle ), it may help in the bump steer/bump stop/ roll center issues.

That's an interesting idea. I have been to their shop however and they are some cool guys (if not a bit crotchety haha). I honestly think the "DIY" drop spindle on the MGB may even be possible since I think they are just built as a bunch of spacers around the kingpin anyway. 

Dusterbd13-michael (Forum Supporter) said:

Id keep springs around,  and trim coils as necessary. I bet you will be able to dial in the height,  adjust bumpstops, and be in a "good enough for the application " place for just a bit of time. And cutting coils increases rate a little, so it may ride better just due to that.

yeah, this is my plan for sure. The stock MGB springs are surprisingly stiff, like 600lbs/inch or so I think i've read. and I can easily stand up on one and it doesn't move too much so I believe it. 

I might even try to move to LESS spring but MORE swaybar and fresh/good dampers. We will see. 

Here's a link to springs rates: Springs 

The lowering springs do get upwards of 600 lb/in, but stock springs are still less than 500 lb/in.  Looking at the chart, I might end up getting MGA springs for my car, or at least see if I can borrow a set from a friend.

Fair enough haha.  And it wouldnt surprise me that they are that stiff.  That stock 1.8 lump is a frekin boat anchor.  Its just under 450 lbs for the stock engine and gearbox.  The L67 im putting in mine weights 450 ish with power steering and all the stock brackets.  Ive got A/C but no power steering and custom brackets, exhaust weights less, T5 trans is 75 lbs so ill be just a hair over the stock 1.8 weight

My bug eye has a 1/4 elliptical leaf spring in the rear.  Bit different than the 1/2 elliptical in the later Midgets and the MGB, but the biggest improvement to handling in that car was a rear panhard bar from Frontline.  It was just ok driving it, never felt great even with new levers, 65 series tires on 14" wheels and poly bushings all the way around.  When I put that panhard on, holy crap.  Just around the block it was a transformed car.  You could now flick it around a corner like it was on rails.  For any live axle car that isnt setup with something to keep that rear centered, that would be very high up on the list of things to do.  Keep that rear end planted, and it just follows the front around instead of trying to do its own thing.

Been a little bit since my last update, but I've basically just been grinding, refitting, grinding, refitting, being confused, grinding more, etc.

I also did the paper templates on the second side, and it was much faster than the first side.

Hmmm, what is this little guy for?

Oh, there you go!

I ended up trimming the corners back down to match the outer angles. And then I welded the bottom on to connect both sides.

It's been a while since I've welded and Ive done better welds than this. Oh well. It was good practice before I start after the body/mount welds.

I am quite happy with it overall though. It should be good support and protection, and it is a little higher up than the bottom of the crossmember, so not reducing clearance or anything.

And we're tacked in! (From underneath).

Nice progress!

No picture this morning but I did some more welding on the engine mounts and I also removed the crossmember again so that I can get better access to finish welding. 

next steps are to finish welding, then bolt all the front suspension back on so that I can roll this outside and pressure wash the bejeezus out of the engine bay. I want to paint the bay rattle can black, but first I need to get the 50 year old grease out. 

Finished welding in the mounts yesterday! Needed some patches for areas I screwed up the templates. Oh well. Also welding above your head sucks!

I even "fixed" the hole in the frame rail.

Next I installed the engine, and after some considering, decided to use the stock trans mount crossmember and mgb trans mount, in one of the miata PPF bolt holes.

Didn't take any before pics of the crossmember, unfortunately.

And in the car.

I still have to get a better way to do the top bolt on the trans mount, but otherwise the drivetrain is in the car!

Everything is as centered as I can get, and the crank pulley angle matches the diff input angle with weight on the rear tires.

Woohoo!

Nice!

Spent some time this morning looking at next steps, in between priming and painting the suspension and trans crossmember semi gloss black.

1. Hood fits well. Nice.

2. Alternator fits in the opening, but there isn't enough room to tension the belt before the alt hits the frame rail. I'm going to try to clearance the rail as I'd much prefer that to getting a different alternator. I'm really hoping this gives enough space.

3. Trying to decide what to do with radiator. The RB radiator sits way forward of the CB one, and further forward than I need. Seems like a lot of surgery to make space for it but thats probably still the direction I'll go.

4. Exhaust. I'll need to cut up the stock miata mid pipe, and then possibly need to make a bit of space right where the drivers right foot goes. 

Here's my exhaust situation. First thing was to cut the miata mid pipe for the flange, and hey, let's use the tubing as well. 

Cut and cleaned up, going to tack and see if this fits.

In reply to Robbie (Forum Supporter) :

Maybe a shorter belt?

AngryCorvair (Forum Supporter) said:

In reply to Robbie (Forum Supporter) :

Maybe a shorter belt?

I thought about it, but that would require some fancy installationing. Since it's a v-belt, you need a pretty good swing on the tensioner to allow enough room for the thing to slip on and off in the first place. Maybe I can unbolt the water pump pulley to install, but I'd rather not go there if I dont have to. 

In reply to Robbie (Forum Supporter) :

Space alt forward and run it off the multi-rib pulley? IDK, I'm just throwing darts here.

In reply to Robbie (Forum Supporter) :

Shorter belt?

Edit: ignore me, already been covered