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Old 09-25-2020, 01:10 AM
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Cobra Make, Engine: SPF 2291, Whipple Blown & Injected 4V ModMotor
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Quote:
Originally Posted by bwcobra15 View Post

I've been having a hell of a time with my clutch/trans lately. Its started after driving a while and coming to a stop, I go into neutral. Then when the light turns green it will not go back into first gear, or barely second. like i'm not pressing the pedal at all. I pump and pump until it finally goes in. I'm afraid i'm going to bend some forks or some such... and then later sometimes it will slide right into gear, no problem!

When this first started happening, I called the Tremec rep and regional distributor for Tremec, where I bought it. He said it sounded like the clutch fluid was boiling (btw he uses and recommends Tilton internal TOBs on all their race cars). But I said I have heat shields and i dont think thats it. He said if you kill the engine and then put it in gear does it glide in? if so then the clutch isn't disengaging. I haven't tried that yet, because I'm always in traffic. Besides, I can't start the engine while the transmission is in gear - I'm using the neutral safety switch.

Then it happened again last weekend on cold start right out of the garage ... so i can't be heat related.

There is a fair amount of heat inside the bellhousing. In fact the first generation McLeod HTOB's used braided stainless lines with banjo fittings to move the brake fluid in and out of the HTOB. The banjo fittings used rubber o-rings to seal at their pivot joint. The clutch heat inside the can would destroy those o-rings after a while and the HTOB would fail requiring a lot of work to replace / repair it.

The newer McLeod's and the Tilton HTOB you are using do not use banjo fittings so they should not experiencee that particular failure. Detroit successfully uses HTOB's in increasingly more and more vehicles. They usually use steel tube instead of braided stainless with banjo fittings — few if any failures. Significantly the o-rings internal to the HTOB which seal the moving sleeve, that pushes the actual TOB against the clutch fingers, do not appear to experience heat related failures.

The shift lever locking effect is a result of the erector set like linkage Tremec uses for the shift rod going between the mid shift location and the rear shifter location. It is simply more moving parts that need to be carefully managed — that sometimes are and sometimes are not. When they are not it is possible to lock up the internal rails. Removing a couple of covers and using a large screwdriver it is possible to free up the shift linkage and reassemble all the pieces you took off to fix the whoopse.



Quote:
Originally Posted by bwcobra15 View Post
This weekend i'll visually inspect the TOB through the bell housing window and see if i can see any leakage, and bleed out the clutch system again. BTW, I use Wilwood Hi-Temp 570 Degree Racing Brake Fluid 290-0632 in brakes and clutch.
The presence of the problem in cold weather and also your use of Willwoood HiTemo racing brake fluid pretty much precludes boiling the fluid. Not that you can't, but in a non race environment I think you would have to work pretty hard at boiling the fluid — especially the Willwood Hi-Temp 570 Degree Racing Brake Fluid.

The difficulty in shifting vs the linkage locking up are two different problems. The shifting problem is typically a clutch that is just shy of completely releasing. Kyleb's approach to finding the clutch disengagement point in his post #14 is a very good and easy to do fix. Unless your bell housing is off center from the crank rear flange that should fix the hard to shift problem.



Quote:
Originally Posted by bwcobra15 View Post
The next question is: I have experienced the same as Wayne shifting from 2nd to 3rd under hard acceleration - I thought I was just missing 3rd, and had to stab it again. Ed, your recommendation in part is to move the shifter forward to the middle position. I'm not sure I would want to do that, having to cut the trans tunnel and carpet for a new location - and I also want to keep the original looking mustang reversed stick shift. Would making the internal only upgrades help with this problem, and possibly the aforementioned problem as well?
This problem has several dimensions. One is the slop that the shift rod from the mid shift to the rear shift position introduces. While not attractive it is usually not the problem at the front of the parade (other than the shift lever lock up problem).

The higher order contributors to the problem, as Liberty explained it to me, were the antiquated 1960's style brass synchronizer rings Tremec uses, the timing of the interlocks machined into the shift rails to prevent engaging two gears simultaneously, and the poorly prepared sliding surfaces for the hubs and sliders. The OEM steel shift forks don't move as smoothly in the synchro sliders as they do when you add the bronze shift fork pads to them, which I would think Tremec would just do for the as delivered transmission, but they don't.

The biggest deals are the synchros and the interlocks. the carbon fiber lined synchros give a lot of new life to the old design but are not as good as the double and triple cone designs used in the T-56 Magnum. None the less they are a big improvement over the OEM brass rings.

When the first carbon fiber lined synchro rings came out, almost 10 years ago now, the manufacturers did not always have the carbon fiber correctly positioned on every synchro and created a new set of shifting problems. I have not heard of that in recent years.

The new and improved interlock timing on Liberty's replacement shift rails is the second last part of the 2 - 3 shift quality problem. The last piece is a slightly modified shift lug, which you can see in the Forte mid shift pics. I'll get as big a pic of this item as I can and post it up in a day or so. The mod made to the lug is small but Forte includes it in his shifter kit and maintains it is important to a happy ending.

In the FWIW bucket, while Hanlon does not show the shift lug in any of his Mid Shift Kit pics that does not mean he does not offer it. I discovered Hanlon after I bought the Forte kit and never called them to ask about the lug. It is entirely possible they also provide / offer it.


Ed
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Last edited by eschaider; 10-01-2020 at 08:15 PM.. Reason: Spelling & Grammar
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