Getting trans plate to align with rear engine mounts

[Joel K]

Joel, just my $.02 but I'd be tempted to split the difference/mis-alignment on bot the bracket and on the plate. Of course, I have a lathe and milling machine and all the necessary bits and fittings to do that which makes it relatively easy. Alternatively, as Neil said, if you have the room/set-back for the fastener head then you can simply plug weld and re-drill too. Personally, I sort of like a bit of a slot instead.....so I can accommodate some lateral positioning if needed.

Thanks Cliff, I do have a light duty milling machine. I think it could machine stainless although I only use it for aluminum. Agreed if I go the milling route I would split the difference. The tricky thing is exactly what direction to elongate since the brackets are on an angle.

Another approach I was thinking about is exchanging these for a set with no holes drilled for the transaxle plate and I’ll line it up and drill the holes myself.

 

[Del]

I had the same issue with mine at the same spot as well. Ended up elongating the bracket hole to get it to fit. Decent bit of trials to get it to work. My cross brace was always tight and barely enough to the the bottom brackets to side in and seated with the help of a rubber mallet.

 

[Mike S]

I had the same issue and talked to Fran. He had me remove everything in the rear (roll bar struts, engine mount, "K" support), loosen the two engine plate side mounts, install the engine plate and gradually tighten everything down. The engine plate and mounts are stressed parts of the chassis. Make sure all of the threads are fully engaged before you start tightening so nothing gets cross threaded too.

 

[Joel K]

I had the same issue and talked to Fran. He had me remove everything in the rear (roll bar struts, engine mount, "K" support), loosen the two engine plate side mounts, install the engine plate and gradually tighten everything down. The engine plate and mounts are stressed parts of the chassis. Make sure all of the threads are fully engaged before you start tightening so nothing gets cross threaded too.

Thanks Mike, I received the same advice from Kristin. She said, mount the plate to the engine and slowly tighten the assembly. I guess it winds up being stressed since the plates will ultimately push the vertical billet Stantions out a bit as things are tighted up. On the flip side, I have heard from some other builders their rear engine mounts dropped in without being stressed.

 

[Neil]

This might be the result of "tolerance stackup". Each hole is slightly larger than the bolt going through it so things can be moved quite a bit if there are many holes and all the bolts are loose. If some bolts are tightened and the bolt s are not in the exact center of their holes, the remaining holes may not line up.

 

[Ken Roberts]

I would remove all the steel tubing as Fran suggested just in case one or more of them are stressing the frame and then check the alignment of the holes but I wouldn't advise forcing it to fit. Many of us had to file fit the holes to match. The goal is to not introduce any unnecessary stress on the frame. The bolting of the adapter plate to the two steel plates will now make this a "new" stressed frame member. Some builders elected to use bushings for engine mounting so I guess technically theirs isn't a stressed member.

 

[Joel K]

This might be the result of "tolerance stackup". Each hole is slightly larger than the bolt going through it so things can be moved quite a bit if there are many holes and all the bolts are loose. If some bolts are tightened and the bolt s are not in the exact center of their holes, the remaining holes may not line up.

Thanks Neil, in this case even with no nuts on the bolts and loose it really doesn’t line up. So when tightening this assembly up something will have to move and that is my concern. Once I get the front engine mount fabricated I’ll decide how to handle the rears. Thanks for all the input.

 

[Neil]

Joel;

If that's the case, something is drilled wrong.

 

[Terry Oxandale]

The assumption is that a jig is used for the framing and machining, and thus all should be consistent. So something has to be different given the varying experiences noted.

 

[Cam]

I think Johan’s measurement sums up what has happened here. There’s a 10mm difference between his frame and yours. Your forward engine mounts seem to be short, about 5mm per side as well. So those 2 pieces of data suggest your frame rails are too far apart and is what’s driving your issue.

I agree with Ken - I don’t think you want to pre stress your frame by having the adapter plate suck your frame rails inward, who knows what impact this could have. There aren’t a lot of hole stack ups between the frame, brackets, and adapter plate and you’ve got nearly 0.200” of translation missing on either side.

I don’t believe the adapter plate sees a lot of loading anyway. Your forward engine mounts will serve as the forward attach points and your rear will be supported by the ears on the transaxle. Any Powertrain twist should be resisted at those points.

Your frame rails at that location are pretty well boxed out by the upper cross bar. So the only thing I see that plate/bracket doing is better distributing the vertical load across the entire length of the rails, as opposed to just at the front and rear.

 

[Mario]

Joel. Is it possible they messed it up at the factory , being they didn’t have your LT 4 there.

 

[Joel K]

Joel. Is it possible they messed it up at the factory , being they didn’t have your LT 4 there.

It’s debatable if this is a real issue or not. For sure, having the engine their would have helped. For my build I am making it emissions legal and left my engine choice to the very end since it was not clear what would pass NJ emissions. Eventually I chose the LT4 a few weeks before the car was ready to ship and was not ready to purchase the engine. So getting the engine in the car is now part of my build process. Just part of the fun.

The instructions from RCR is to remove any braces that mount on the rear structure, loosen the rear mount bolts, then attach the trans plate to the engine block and slowly tighten everything up and it will fall into place. I don’t think this is what I will do, probably elongate the holes so there is no pre-load. A little bit of work. After that, I may weld a plate to the bracket with a single round hole lined up to where the bolts need to be.

With regard to the front brace being a bit narrow, it really doesn’t matter much since that brace is for the LS3. Although another builder ran into the same thing. I am in the process of making a new front mount. Just going slow to get it right.

Also, I’ve checked my bottom frame measurement against a couple cars and it seems .25” wider, but then checked the top rails against another chassis and they are 1” wider. So my guess is the dimensions have slightly changed. Having the top rails wider for me is a good thing and makes getting the LT4 accessories to clear the top frame rails easier.

Being a new builder I am erroring in asking a lot of questions and the members on the forum have been great. The reality is there are times you have to make the parts fit and that is part of the process.

 

[Scott]

Joel,

My LS7, transaxle adapter plate and brackets were installed by Superlite. During a visit pnut asked me where myshift cable bracket was... I didn't know that I needed one. I bought one, but I couldn't get it to fit because it was hitting the rear suspension cross brace. After speaking with several SL-C builders with Ricardos, they all had zero issues with theirs and significantly more space between the transaxle and the cross brace. Allan looked at it and told me my engine wasn't sitting level. We put a digital level on it and it was sloped almost 3 degrees upwards towards the back. We compared my brackets to the brackets on the Graziano car that's he working on and they appeared exactly the same. I called Superlite and explained all of the above, but they insist that I have the correct brackets. It would be nice if there were part numbers or some other way of knowing exactly what's installed.

I brought the car to a race-car fabricator last week. The bracket / adapter plate bolts were hard to remove and the fabricator asked if the adapter plate was threaded. I told him I didn't think so. In any event, the only way to remove the bolts was to use an large impact gun. All of the plating was stripped off of the grade 8 bolts, aluminum speckles were falling on the floor, the hole was "threaded" at an angle and the nice chamfered edge of the hole were jagged from having the bolts forced in at an angle. The hole in the adapter plate is so trashed that even when the bracket is removed the bolt won't slide through. In fact, I needed to use a socket wrench because it was too tight to spin by hand... I guess there's a reason a tap has channels to evacuate chips when threading a hole.

Here's what the hole looks like after removing the factory-installed bolt.

I spoke with Allan who's built something like 25 Superlite cars. According to him, most of the bolts go right through without issue. In a few cases he's had to loosen the three bolts on the brackets before tightening everything (similar to one of your pictures) and in a couple of cases he's had file the hole in the bracket maybe up to 1/8". So, he's never seen anything like what you're describing.

The only conclusion for my situation is that I have the wrong bracket. Even with the bolt being inappropriately forced into the hole, the location of the hole is off by at least half an inch to get the engine level and to get the shift cable bracket to fit. Since there are no part numbers to prove to Superlite that they installed the wrong brackets and they likely don't have any Ricardo brackets sitting around, I've decided to make custom ones.

If the transaxle plate is supposed to be a stressed member, then the manual should point that out. I just checked and it doesn't.

The first thing that I would is validate that you have the right bracket (I assume that they must have 6 or 8 versions of that bracket for different cars/transaxles). The easiest way to do that might be to trace, scan and email it to someone who has what you think you're supposed to have. If you have the correct bracket, I can't imagine that any amount of loosening stuff is going to solve that big of a discrepancy. At that point you would need to weld and re-drill your brackets or make new ones.

 

[Alex]

The LS/Ricardo adapter plate is a tight fit ... I have to smash the bolt in/out with a hammer ... but it does fit. I don't think my drivetrain sits level. Post what your shifter bracket looks like and I can tell you if it's for Ricardo or not.

 

[Del]

I spoke with Allan who's built something like 25 Superlite cars. According to him, most of the bolts go right through without issue. In a few cases he's had to loosen the three bolts on the brackets before tightening everything (similar to one of your pictures) and in a couple of cases he's had file the hole in the bracket maybe up to 1/8". So, he's never seen anything like what you're describing.

I had to do both, file my bracket and loosen my engine mounts to mine to get it to line up to get that bolt in and out as well as secured on the adjustable crossmember. There was definitely lots of raising and lowering engine to get it together.

 

[Joel K]

Joel,

My LS7, transaxle adapter plate and brackets were installed by Superlite. During a visit pnut asked me where myshift cable bracket was... I didn't know that I needed one. I bought one, but I couldn't get it to fit because it was hitting the rear suspension cross brace. After speaking with several SL-C builders with Ricardos, they all had zero issues with theirs and significantly more space between the transaxle and the cross brace. Allan looked at it and told me my engine wasn't sitting level. We put a digital level on it and it was sloped almost 3 degrees upwards towards the back. We compared my brackets to the brackets on the Graziano car that's he working on and they appeared exactly the same. I called Superlite and explained all of the above, but they insist that I have the correct brackets. It would be nice if there were part numbers or some other way of knowing exactly what's installed.

I brought the car to a race-car fabricator last week. The bracket / adapter plate bolts were hard to remove and the fabricator asked if the adapter plate was threaded. I told him I didn't think so. In any event, the only way to remove the bolts was to use an large impact gun. All of the plating was stripped off of the grade 8 bolts, aluminum speckles were falling on the floor, the hole was "threaded" at an angle and the nice chamfered edge of the hole were jagged from having the bolts forced in at an angle. The hole in the adapter plate is so trashed that even when the bracket is removed the bolt won't slide through. In fact, I needed to use a socket wrench because it was too tight to spin by hand... I guess there's a reason a tap has channels to evacuate chips when threading a hole.

Here's what the hole looks like after removing the factory-installed bolt.

View attachment 97757
I spoke with Allan who's built something like 25 Superlite cars. According to him, most of the bolts go right through without issue. In a few cases he's had to loosen the three bolts on the brackets before tightening everything (similar to one of your pictures) and in a couple of cases he's had file the hole in the bracket maybe up to 1/8". So, he's never seen anything like what you're describing.

The only conclusion for my situation is that I have the wrong bracket. Even with the bolt being inappropriately forced into the hole, the location of the hole is off by at least half an inch to get the engine level and to get the shift cable bracket to fit. Since there are no part numbers to prove to Superlite that they installed the wrong brackets and they likely don't have any Ricardo brackets sitting around, I've decided to make custom ones.

If the transaxle plate is supposed to be a stressed member, then the manual should point that out. I just checked and it doesn't.

The first thing that I would is validate that you have the right bracket (I assume that they must have 6 or 8 versions of that bracket for different cars/transaxles). The easiest way to do that might be to trace, scan and email it to someone who has what you think you're supposed to have. If you have the correct bracket, I can't imagine that any amount of loosening stuff is going to solve that big of a discrepancy. At that point you would need to weld and re-drill your brackets or make new ones.

Scott,

Well you have a stressed fit for sure and that is what I am looking to avoid. Even if it’s only to just make it easier to remove the transaxle if necessary. Functionally my guess is stressed or not the trans will be held securely in place. With regard to the engine-trans being on a slight angle I have no idea if that matters at all. It may not based on engineering principles. I just don’t know. I was planning on making it level if possible but would appreciate some feedback on this topic.

 

[Johan]

Joel,
I think the best way to fix this is to weld the holes and redrill after procedure in Cam’s post #9.
I would definetly not put any preload on the chassis by loosening the brackets and retightening.
Your problem is your lower longitudinal beams spaced too far apart, just correct it with new adapter plate holes.

 

[Ken Roberts]

The LS/Ricardo adapter plate is a tight fit ... I have to smash the bolt in/out with a hammer ... but it does fit. I don't think my drivetrain sits level. Post what your shifter bracket looks like and I can tell you if it's for Ricardo or not.

The shifter bracket on the Ricardo transaxles were not supplied by Fran. The OEM brackets were used. Scott bought his transaxle from Europe. It didn't come with one installed I assume. I had to trim mine at the top to get it to fit under the cross brace as shown in the picture. I even re positioned the top hole for a better line up with the arm.

Sorry for the thread drift Joel.