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Trans not centered in tunnel - new TKO

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So after I toasted the T10, I bit the bullet and ordered a TKO500 5sp from Modern Driveline. Gorgeous piece of machinery!  I got it "in" this weekend... sort of. 

Checked the bellhousing runout and flatness, all within spec. TKO went in fine and up snug against the housing without forcing. But its not in the center of the tunnel: notice the shifter in the cutout:  


...which is causing it to hit the tunnel on one side before getting fully up into position. This has to be a problem with the motor mounts/frame, right? There is nothing else I can think of to adjust. I loosened up the mounts (stock) but they won't let the powertrain rotate. The T10 didn't have any problems, but it is quite a bit smaller than the TKO so I may just not have noticed. 

I am suspecting it is something to do with the shock towers; can't remember if the body shop replaced one of them or not. I would bet a small error there will move the tail end of the trans quite a bit. 

Solutions? Only thing I can think of is some adjustable motor mounts like Ron Morris: http://www.ronmorrisperformance.com/miva/merchant.mvc?Screen=PROD&Store_Code=rmp&Product_Code=6110 to allow the engine to move forward/back on each side and rotate a bit. I also have a slight (1deg) tilt from side to side. Might be able to solve that with some shimming. 

Anyone ever change a motor mount WITHOUT removing the engine?  I am almost done with this build and it seems like I am removing more stuff than I am installing... 

And what pinion angle from level are you seeing at the back of the trans? Even when I get this in the center, I am not sure it will go all the way up to the stock height at the trans mount. 


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Cross member won't flip, its offset so the other way round it will be under the case instead of the mount holes. MDL suggested loosening the mounts. Did that, pulled three of the four engine bolts thinking I could pivot it a bit around the remaining one. Sucker will not budge! Thought it was hitting the zbar so unbolted that but still won't move. (Seriously regretting unbolting the zbar, that is going to be impossible to get back in.)

Maybe just too much weight still on the mounts to move? Need to drag out the joist and pull the engine off the mounts to see if they free up. Hell I ought to be able to hang the thing in the air and line it up, right? 

What did  you use for clutch operation in yours - keep the zbar or cable or hydraulic? My zbar was working fine on the T10 so I figured I'd just keep it for now.


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Picked up some Ron Morris mounts, really nice. Easy to move the motor around. Now the trans tail is centered better, trans mounts line up. 

But... the tail seems really low. The tail shaft is about at the bottom of the tunnel, not IN the tunnel. Pinion angle from the trans to the driveshaft is about 5.5 deg, and I still need to lower the rear which will make it worse. The z-bar is tilted down on the engine side, and hitting the exhaust.

@rwcstang, where is yours sitting and do you know what the pinion angle came out to? Anyone else do a TKO?

MDL thinks 6 or 7 deg is ok, but everything I have been reading says it's way too much. Any thoughts?





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When i did the TKO 600 swap in my 69 I had to shim up the back of the trans to get the driveline angle acceptable. I called MD and basically they said to put a piece of cardboard over the top of the trans ...jack the trans up til it hit the rib on the floor..then lower it just enough to remove the cardboard and that would be acceptable clearance. Mine did not sit " perfect in the opening" as the opening is not symmetrical. It appeared to sit over towards the passenger side but when you look at it the rib on the floor on the left  sweeps away further than the passenger side which is more vertical. That was done purposely at the factory to allow more room for shifter rods etc. Made sense to me.

Technically If ordered from MD you should order the TKO with the 'low profile' covers..that way you can get the trans up further in the tunnel without hitting anything. And the covers hitting on the right side was my problem.

One other note..not sure what shifter you got with that trans but i ordered the shifter with a 1" offset to the left and rear and that put the shifter in the center of the opening to match the console. Food for thought.


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Thanks John. Yep heard the same about not needing much clearance. I am about 1/8-1/4 from touching. Side - to - side is fine now, the tko sits a bit to one side. Plus the shifter is not directly over the driveline. All good there. 

Now the issue is vertical angle. I estimate the TKO is about TWO INCHES lower at the tail than the original T10! I am getting 6deg down. Seems like way too much - looking under the hood you can see the engine is tilted a hell of a lot backwards. Looks goofy.  I was just reading your post from '17 on your install. Did you sort out the driveline vibration? Did you get the rearend up to 6? Did it cure the vibration?  Even MDL's site says 6 degrees is max 3000 rpm. 

Thanks... Dave.

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I got it up to @ 5 degrees Dave and up to now i have lived with that. Minor tremble between 60-70 and then it disappears...still annoying though.  I did purchase the low profile covers for mine but haven't installed them yet as it entails removing the trans and mounting it in a mill to mill the surfaces down to the required gradual incline. That will let the tailshaft go up further with the covers not hitting on the passenger side which was the case (pardon the pun) with my interference issue. My plan is to do that at the same time im building a stroker 428 for it.

MD now sells a streamlined case as i mentioned and after all the issues i had i think everyone should purchase those trannys with the mod already done or go to that new TKO that theyre now selling. I guess finally that company got the message that these transmissions are too invasive for the Mustang tunnels.

Best regards...John

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I did the MDL TKO 600 conversion several years ago and did not have any issues like this. It did come with the offset shifter to line up with the console, but otherwise everything lined up right. I have about 3 degrees of driveline angle.

I added the Ron Morris adjustable motor mounts and moved the engine to the right for header clearance with the borgeson box, but that didn’t impact the transmission much

I would check to see if you have your motor mounts swapped, they are side specific - the part that attached to the frame

Edited by jpfll
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Thanks guys. 

John - yes 5 deg sounds like a lot and probably causing that vibration. I saw the lower top covers but from MDL's feedback I shouldn't have needed them. Guess there is a lot of variation in body dimensions. MDL said to "go ahead" with my 5-1/2 deg but I don't really want to. Looks... wrong. 

Jpfll - I had the stock mounts correct, and with the Ron Morris mounts they have plenty of play so OK now. Definitely made it easier to align side to side. 

I have the 1/2" lower RM mount plates too, so will try those this weekend and see how much difference that makes. That will eliminate the use of the zbar as the engine will be too low. Not necessarily a bad thing, just more work and money for cable or hydraulic.  Plus I *really* hate brake fluid... Or, I can cut and lift the tunnel. Doable just more PITA work. Funny, was just watching Bitchin' Rides "Fireproof" episode where they fix a '68 with TKO and bad vibration.  They cut the tunnel to get the pinion down to 2deg. 

The real problem is that the tailshaft on the TKO sits almost 2" lower that the T10, from the mounting holes for the cross member. If you ignore the car and just measure Mount hole - cross member surface - mount thickness (same for both) - mount surface on trans - CL of driveshaft. 

I think I was about two months too early - the TKX looks like a much better way to go. Can be ordered with a 6.5 input shaft, so no spacer. Same length as a Toploader so no new driveshaft. It should be literally plug-n-play with a new crossmember. You can see the size difference - all the blue areas are gone:



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@dbmac I am experiencing same issue as you with the clearance for my TKO. I have the Ron Morris mounts as well so getting the engine positioned hasn't been a problem. Thinking of cutting the tunnel and adding a spacer to the mount. Wondering what you did to solve your issue? Also found this kit from Hurst to raise the tunnel. Any experience with this? Looks like it is designed for the situation. 



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Hi @Gray69,

Glad you tagged me, I have been meaning to share the outcome... 

I purchased that tunnel kit thru Summit. Not impressed. The pieces don't line up with each other and it would take a bunch of fab to complete. It is way longer than it needs to be. 



I cut my tunnel a bit at a time and kept moving the trans up until I got the pinion angle back to normal - about 2deg down. The carb is now dead flat (intake manifold has a couple degrees in it). First I tried keeping the shifter boot ring, but that still wasn't enough for the TKO, pinion was still 4-5 deg:


I ended up opening it from the kick up at the firewall to the back just past the shifter ring, before the tunnel turns down a bit: 


With that cutout it is almost a straight line from the back to the firewall. had a piece of sheetmetal cut at SendCutSend (online laser cutting folks, awesome) and folded it on a bench over a pipe to radius the sides. They are slightly splayed towards the front. Then trimmed to fit the cutout with about an inch of overlap:


The straight line worked but was a bit high under the dash, so I slit the sides and angled it down at about the back end of the second top cover plate. Its about parallel to the two front covers. I also slit the folds near the back ends to taper that in a bit more. A bunch of tack welds later and it was in:


Best part - did NOT set the house and garage on fire! Not beautiful but hey, its under the rug... Some grinding, primer, seam sealer, paint and POR Undercoating on the bottom and it looked pretty neat (meaning not messy):



Before everyone starts criticizing, no did not stiffen the brace. Yes I know it does not have a solid frame, but I do not think the car will "wad up like a pretzel". If it does, I'll post pics. 

The trans is now dead center at the tailshaft, which puts the shifter slightly offset. With the offset shifter base it comes out ok. 


The mount needed a 1.5" spacer ( I used thick aluminum square tubing). I kinda wanted to modify the mount, but its already above the bellhousing so not too low. 


All buttoned up and you'd never know what happened!


I used a Lokar machined ring and a Scott Drake boot. Drake boot has a different hole pattern but I was able to drill it to match the ring. It is a nice leather piece. The Lokar boot was just vinyl, looked a little cheap. 

I also lowered it 2" in the back and about 1.5" in the front. Dead flat now and much better stance. I rolled the front fenders a while ago, no rubbing except full lock turns over bumps:


To celebrate, I took her to our first show! Just a local meetup with all sorts of cars, a lot of late model stuff and some classics. How do we look with all the fancy stuff? 


Overall I am very happy with the TKO. A bit of a pain to get in, but works well. NO vibration or noise from the driveline. Still need to put the Posi gears in the rear but it has a lower first and better freeway cruising speed in 5th. But it definitely does NOT fit without modifications, especially if you keep the Z-bar for the clutch. Any angle change on the engine and it will not fit - that's how I knew my mounts were not the problem - my zbar was aligned perfectly. 

If you go with a hydraulic clutch setup you could drop the engine or live with a steeper angle and cut less. 

If I were to do another, I would definitely start with the TKX. The real interference with the TKO is the wide top plates; the TKX has no plates, is rounded and a bit shorter. Might even fit without modification. 

Hope that helps. Let us know how yours goes. 





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