BritishV8 Forum

QuoteSweet also makes a 3/4"-48 that works on stock MGB steering columns and shafts (401-51010).

Appreciate it Paul!

Uni-steer and Flaming River make the lower joint you need  or you can shim the stub at the rack and weld 3/4" round to 3/4" DD. The MG shaft is slightly smaller than 3/4". That is why I recommended the 17MM DD Jeep pinch to 3/4" DD. You could also use the Borgeson MGB 48 spline to 3/4" DD vibration damper ujoint.. Speedway Motors  carries the DD shaft. Rig it up with wooden dowels first and it will be perfect.

Yes, I made all my shafts out of 3/4 dowel rods first and then transferred that to steel.


Paul

I know Scott has picked his motor mounts. Here's another mount option.

http://liquidironindustries.com/GM-LS-Motor-Mounts.html

Made more progress this past weekend. Measured for the motor mounts and cut the frame mounts. Next step is to assemble the mounts and weld them to the "frame" rails. I keep mentioning that there are a lot of details and this is not an exception. I'm going to wait until I actually complete a task before I share the details so I don't pass on misinformation as some of the details are in flux until the task is actually completed.

I don't think I shared a picture of the engine/transmission combination yet so here it is.



I measured the steering shaft and got about .730". Jim N., I know you are recommending the 17 mm DD u-joint but after considering things, I'm going to do something different. (What else is new ). I believe I'll be going with a 3/4" DD u-joint mainly because I have some concerns with how the 17 mm pinch u-joint is going to fit with the clearances I have. I'll shim it with .01" shims.

I'm still making good progress and having lots of fun...I'm trying to make sure I get something done every week. Also still very excited about the big changes this will be making to my car.

If you have any questions, I'll try to answer them.

Not sure this is the right place to post this but I thought this might interest some of you. The following pictures will give you an idea of how a RWD car/truck motor (4.8/5.3/5.7/6.0) might fit in a B with the same set back I'm trying to achieve with my LS4. Although it may seem like it to some of you, I'm NOT bashing those motors. They have been and are successfully used in MGBs regularly. I suspect there will be many more of them used in B conversions in the future rather than the LS4. Also, the majority of them will not be placed as far back as I'm going with the LS4 and therefore the firewall mods won't be nearly as extensive as depicted here.

Anyway, what got me thinking about this is the fact that you can see much of the SBC bellhousing bolt pattern on the LS4 block so it illustrates some of the differences quite well in these views.

I think it's pretty obvious but the red marks are the large bellhousing bolt/dowel holes and the green is roughly what would need to be removed (in my estimation so take with a grain of salt) to accommodate the larger bellhousing if the motor were set back this far.

a 98 Camaro steering has a nice set of ujoints, diameter is smallish and good for high angle change. look how chevy packaged the camaro steering

More progress this weekend. I decided to attack the steering before the motor mounts as I needed to know where the steering ended up before positioning the motor mounts. I went with the Sweet steering u-joints. 3/4" 48 Spline for the steering column end and 3/4" DD for the remainder. I took the advice from Jim and Paul and used a 3/4" wood dowel for fabrication....excellent idea! Here is the result.



I lowered the steering a little less than 2" at the firewall. It actually wasn't very difficult to do. I modified the pinion shaft myself. Took my time and the u-joint is very snug with no play. I need to order a DD shaft, finish the set screw modifications for the u-joints and weld the cone into the firewall. FYI, the DD shaft will be a hair less than 14" long. I believe this is the easiest approach to the steering issue. I really wanted to keep the rack in the factory location and messing with the rack mounts to lower the stock shaft looked time consuming. Ignore the brake lines, they will all be replaced and rerouted before I put the car back on the road. You can see the position of the steering wheel after the lowering here.



It raised the rim of the wheel about an inch or so.

There is a fairly big hole from trimming the passenger side firewall but it really is pretty much dead space from the perspective of usable space in the foot well. You can see from this shot what I mean.



So motor mounts should be next and then the exhaust. I figure if I can have those tasks completed by early January I should be about where I need to be for the V8 Meet....we will see.

Scott. Good Work! You could still rotate lower end up or down if needed for clearance without moving the rack too much. Use angled washers for angle iron on upper and lower rack mount with longer bolts.

I'm slow but getting there inch by inch. Just about got the motor mounts there. This first picture shows the mounts tacked to the "frame rails".



I need to remove the passenger side mount and shorten it so the mounting hole sits closer to the frame. I should be able to complete fabricating the mounts on the engine side once that is complete. In the following pictures, the engine is positioned where it will live going forward. This first shot shows the clearance on the pulley. I was actually able to get a belt between the rack and the pulley so that was good.



This next picture illustrates, I think, just how compact the LS blocks are.



This view makes the B engine bay look big front to back. It fills the bay up side to side, that's for sure, but it does fit. As you can see in the next picture, there is plenty of room for the header pipe and spark plug wire now. Moving the steering shaft down was well worth doing.



I should have a few days/evenings to work during the holidays so I'll keep plugging away at it. I hope to order my header pipe today.

Merry Christmas everyone!

Scott,Looking Good!

Not quite there yet with the motor mounts but getting dangerously close. This first picture shows the drivers side engine mount tacked together. I'm pretty pleased with the way things are turning out.



The next shot shows the same side with the engine in the car.



Except for permanently welding the engine side of the mount, adding a couple of gussets and drilling a hole for the rubber mount this side is done. Oh, I will need to make sure the steering shaft has clearance on the mount as well. Still a few tweaks needed on the passenger side and then the transmission mount needs to be completed. Hope to get it there in the next day or two. It will be nice to have the motor permanently installed in the car.

While I was working on the car, this came.



I used Ken Hiebert's suggestion and went with Columbia River Mandrel Bending. Of course, I only ordered one pair of exhaust flanges instead of two and forgot the O2 bungs so they will be getting another order.

I'll have more detailed descriptions and pictures once the mounts are completed.

Scott, the mounts look strong but there is a weakness that you might want to consider while there is still plenty of time to address it. I've been thinking about whether or not to say anything and have decided I should.

The attachment to the frame rails in itself is strong enough and well designed, but it is welded to thin material, and I'm not sure it will hold up. Over time I can see the frame rail developing stress cracks around the mount welds because the stresses are concentrated in a relatively small area. You might want to think about what you could do to spread out the loading, and there may be some fairly easy way to go about it. I'd guess the torsional loads are going to be the biggest factor.

If you hadn't welded them on yet it'd be a fairly simple matter to plate the rail with some 12 or 14 gage under the mount. If you do that (meaning cutting the tabs off and rewelding) do not run your front and rear edges of the plate vertical. Best practice in frame repair is to spread the load by using round, diamond shaped, or diagonal front and rear edges to spread the load out on the frame. If I was doing it I think I'd also drill some holes in the plate under the tab and use those to spot weld the plate to the frame before welding the tab on. That will let you get by with thinner and lighter plates.

I know I just made more work for you, but hey, I'm only here to help!  

Jim

Scott, Nice shoes, I had a pair like them once. Dog carried one off, someone threw the other away. I was lost till I found a new brokein pair.
I agree with Jim B, I don't know why, is there room to add a plate from the rear cross member bolt to the welded engine mount?  The metal of the frame is light weight and now it is brittle due to welding, with no way to relieve stress. I am enjoying your post and efforts. I am just starting my 60v6 swap.
charles

QuoteThe attachment to the frame rails in itself is strong enough and well designed, but it is welded to thin material, and I'm not sure it will hold up. Over time I can see the frame rail developing stress cracks around the mount welds because the stresses are concentrated in a relatively small area. You might want to think about what you could do to spread out the loading, and there may be some fairly easy way to go about it. I'd guess the torsional loads are going to be the biggest factor.

Jim, thanks for the feedback, sounds like a good idea. Not sure I'd cut the mounts off but I think I can strengthen them anyway. I've welded the mounts directly over a supporting tab for the rear crossmember bolt so it isn't quite as weak as it might appear.....still needs something more. I'll get it done before I put the car back on the road.

Scott

Ok, I know what I'm going to do about strengthening the mounts. I'll run a couple of gussets on top of the current mounts to the very top of the "frame rail". For good measure, I'll weld the seam at the top of the rail as well. That should address Jim's concern about stressing the thin metal on the side of the rail and will be fairly easy to accomplish at this stage of the fabrication. I'll have to get creative around the steering shaft.

Scott, Just a suggestion but, an easier way is to use a plate like on your motor about 3" wider than the mount on each side and same height as frame, notched to go over lower mount. Grind and weld in frame seam. Matching top frame plate and little square piece under mount. Weld all together. No steering issues. Hey, did you get your clutch stuff yet?

Ditch the rubber X frame mounts and build a tab down to the X member.
Stronger body, stronger mount, better suspension but more noise.
Good trade off.
Cheers
Fred

QuoteJust a suggestion but, an easier way is to use a plate like on your motor about 3" wider than the mount on each side and same height as frame, notched to go over lower mount.

Jim, I appreciate the suggestion. I considered that approach earlier but I think adding an upper gusset to each side will be just as strong and will be easier/quicker to complete.

QuoteDitch the rubber X frame mounts and build a tab down to the X member. Stronger body, stronger mount, better suspension but more noise.

Fred, thank you! Interesting suggestion. The cross member pads you see there are brand new, never used urethane pads I just put in last month. I know they aren't like a solid mount but they will do for now. They should be much better than the 46 year old, flattened rubber pads I pulled out of there. I'll file this suggestion away for when I get to the suspension. I have a pair of GAZ coil over shocks I want to use on the front end...had them for over a year but just can't seem to find the time to put them on. How would you implement the solid mounts, steel replacements for the pads?

I think this might be good time to say a few things that have been on my mind lately. I REALLY do appreciate the feedback I'm getting from everyone. I would have done a journal if I didn't want feedback. It seems like I'm always ignoring some of the advice I'm getting but as "Project Manager" for this project I have to keep in mind the overall plan/timeline I'm working toward. When I get a suggestion that affects the overall plan in some way, even though it might address the current task, I have to look at the effects of implementing that suggestion. So far the plan is working out really well so I'm not inclined to make any changes to it unless a huge issue comes up. I trying to not let this become a multi-year project and constantly changing the plan is a sure way to get there.

Anyway, what I'm trying to say is although it might not seem like it at times, your comments are very welcome. One of the main reasons I'm doing this is to learn and I guarantee you I will be making mistakes.

Happy New year!

Don't forget, someday, someone doing a similar swap, will do a search & find this thread. The additional ideas presented here may be fuel for thought for them. Thank you, Scott, for the non-journal approach.

I'm with Fred, though.  I looked over your pics & I kept thinking subframe mounts. Hey, they are available for Ford.  Maybe time for some Chevy subframe mounts.  

I'm not a fan of subframe mounts. I used those on my original conversion and the stancheons were plenty strong but the (215) motor mounts needed a through bolt to counter mount separation from torque and even then they weren't good at torque resistance due to being close together. They also weren't all that easy to get the bolt in and out when changing the engine. But the worst thing was that the torque caused the frame rails to crack around the subframe mounting tubes. All four of them. Now granted I was also running stiff lowered springs and competition shock valves and I drove it hard so it was undoubtedly the combination that did it, but I had less torque than an LS4 I think. I just don't see running engine torque through the subframe to frame mount as being a great idea. It seemed like it until I tried it, but also consider if you will, the subframe attachment is designed to move. Consider if you will, the massively larger and greatly more widely spaced mounts of the cradle used on the TR7 and all modern cars by comparison. The MGB attachments are not really designed for it.

We're transferring a lot of torque to a small vehicle with thin structure and all that torque goes directly through the motor mounts. You have a factor of about 10:1 between what is seen at the axle and what is seen at the engine in 1st gear but the axle mounts are spread out over a considerably greater distance. In the case of the MGB, the length of the spring leaves and doubled, yet some still feel the need to add channels to support the front spring hangers, and doublers spread the load out into the body.

At the front, the stock mount brackets are fine for the 1800 and the later mounts are OK for the 3.5 and arguably for the 3.9 but more powerful engines require more substance. (Even the stock mounts sometimes crack so that part of the car definitely is not overbuilt.) The first consideration is distance between the mounts, since this directly affects the amount of torque that can be absorbed. Shorter distances require larger cushions, stronger brackets, and more load spreading.

This is a big part of the thinking that went behind the head-to-frame mount design I created for the MG-Roadmaster and my blown 340. It gains at least a couple of inches on the lever arm length, allowing smaller cushions to do the same job. It uses a reinforcing plate on the rail to spread the load out. And it uses a vertical tube to simplify install/removal. But everything is a compromise so it requires realignment of the pulleys and leaves scant space for the wiring to sneak past.

Scott, I think the gussets you have in mind should do pretty well, though they won't do much for ease of installing/removing the main bolt. A gusset of some type to the front and rear might also be helpful. The larger of an area of the frame rail that you can tie into the better.

Jim

I think Jim makes a good point, I was concerned about welding my mounts to the frame rail so I bent a sheet metal cap over the rail to weld the mount to. On the other hand, it's not like you're going to experience a catastrophic failure. More likely cracks as Jim said. You do have quite a bit of surface area where it welds to the frame, a lot more than mine. I'd do the same as you, add the gussets and move on to the next hurdle! You're going to have a lot of hp and torque, but it's not like you're going to hook up hard and transfer all of it to the mounts.

Good luck with the headers, I sure wish mine had turned out a little nicer.

First weld a flat piece of steel to the frame rail, this gives a foundation, then weld the motor mount pads to the lat steel that is welded to the frame. This should be key to fit on top of the rail and welded for added support.
similar to the original MGB mount.

Everyone,
Thanks again for the great feedback! I hope to have a few hours this evening to devote to the mounts.

Carl, if someone wanted to go with subframe mounts (despite Jim's concerns) it would be very doable. With the setback I'm using the stock LS motor mount location lines up quite well.

Hope everyone had a good new year.

I guess that I should have elaborated a little more on the tab idea.
I would do a 3/4 wrap around the frame rail with 0.250" material
It's overkill for the purpose but it lets you wrap it under the subframe mounts and eliminate the bushings.
Drill it with lightening holes and trim it out as Jim described before welding it in place.
A tab down from this plate would then tie into the subframe making it a solid structure.
The motor mount would be welded to the plate on the vehicle frame much as it is now.
I'm in total agreement with Jim regarding mounting the engine from the subframe.
The loading and severe angles required would cause a failure sooner or later.
My intention is to make the subframe and vehicle frame one solid structure.
With so much material removed from the firewall you need to buy back some structural support.
And this is an easy place to start.
A nice solid trans X member. Yes an actual X shape. Tied in well to the vehicle frame.
With forward facing struts that would bolt up to the lower portion of the front subframe.
And rearward struts that would tie into the rear spring mounts.
Would give you a pretty solid base.
A well designed roll bar or cage (better) would add even more stiffness to the structure.
Anything that can be done to improve the body rigidity should be contemplated.
Because that thing is going to want to pretzel up bad.
Hope that's useful.
Cheers
Fred