Let’s keep this thread respectful and continue having a meaningful discussion.

I have been doing a ton of research and like Bastarddsm mentioned the issue with the Evo III 3/4 gears is that the pitch circle is smaller than the other DSM 3/4 gears…this is how Mitsubishi was able to keep the same tooth count on the intermediate shaft. The Evo III 3/4 gears are NOT as strong as the OEM DSM 3/4 (i.e., 90, L91-E92, etc.) because of the tight corner radius and the fact the smaller pitch circles on the input shaft 3/4 Evo gears will increase the bending force on the intermediate shaft gear teeth.

The main issue with the 1990 DSM 3/4 gears is that they are no longer available from Mitsubishi—discontinued for many, many years. They are probably the strongest Mitsu gears, but don’t shift well at high RPM because the synchro cone angle being too large…they just don’t shift well above 7000rpm period and I’m certainly not going to be utilizing unknown/used ‘1990 gears’ in my build.

I looked into the PAR Engineering synchromesh engagement straight cut gearset as it sounded promising and a viable solution to my problem. PAR claims “immense” strength and durability with a 700ft/lbs rating. I spoke with a very knowledgeable member on here that had experience with their gearset and reported regularly breaking their input shafts, as well as exploding 3/4 slider and breaking teeth off of 1st, 2nd and 3rd gears on ONLY a 600whp car. Disappointing to say the least!

Then there are the Boldt Mechanics stronger straight cut synchro 3/4 gears. There is not too much information out there about these in general and in regard to how well they are holding up (lifespan) in real world applications—if they offer significant or negligible increase in longevity, fatigue resistance and overall durability/strength. I may end up buying these gears however, they are relatively new to the market and low volume so I will wait to get a consensus on how they are performing and holding up before I throw down $3000+ on 3/4 gears from Germany.

With that said, please post with any relevant info and experience you have had with the Boldt Mechanics 3/4 gears and how they are working out on your car.

Lastly, I keep hearing all these claims regarding the Jacks Trans Super HD build…including having a “large 4th” gear etc., anyone actually had one of these apart to verify any of this? And keep the posts coming regarding your experience with the Super HD build or the like. Thanks.

keltalon said:

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Thanks great post!

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Keltalon-

Could you please give us details on the pic you posted above. Thanks.

mavericktsi83 said:

Keltalon-

Could you please give us details on the pic you posted above. Thanks.

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The thicker gear on the left camE from a 1g 1990 transmission smaller ring syn chronizer its thicker than the gear on the right which came out of a 1998 2g transmission larger single 3/4 synchronizer ring. The slider hub is the thicker stronger hub for the 3/4 gears and it cam out of the 1990 unit and will not explode like The larger weaker hub slider that in the 2g fwd transmission.

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evo 3 on left, 90hd on right, broke evo 8 4th at bottom.

I dont agree with the pitch circle on evo 3/4 makes gear weaker. Like I stated already, every gear failure is the same. whole tooth snaps off. evo gear teeth have waaay more area holding it onto base. I have my doubts the 90 gears are even stronger. but I respect the opinion of TRE. I personally have broke six transmissions between my two cars. two HD 90 and two evo3/4. the evo gears lasted about three times longer in my cars. 10000-15000 miles vs. 3000-5000 there was about 450tq on evo gears. and about 510tq on the hd 90 gears so not the greatest data. i also dont agree the shape of tooth being thinner at top has anything to do with breakage. tooth flex is not bad thing. short stiff axles break more than longer flexy ones. it would be no different for gear teeth. as i understand it from john the 90 gear teeth are stronger because of how they are machined. there is a less defined score mark after machining. the score mark is where the tooth snaps off.

also in my car with tilton carbon/carbon the 90 gears shifted as good at 9500 rpm as they did at 3000rpm. NEVER lost a race from blocked shift. shifted like butter.

Well, now that jacks is no longer building dsm transmissions we can hopefully get just the hd gears from him.

donniekak said:

Well, now that jacks is no longer building dsm transmissions we can hopefully get just the hd gears from him.

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Is that so wow!

Can't believe it. Guess it's time to learn how to rebuild my own transmission.

donniekak said:

Well, now that jacks is no longer building dsm transmissions we can hopefully get just the hd gears from him.

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According to JT one of the reasons they dropped the build is that they can no longer get the "S-HD" gears.

Read the thread. Mitsu is slowly discontinuing parts

mavericktsi83 said:

According to JT one of the reasons they dropped the build is that they can no longer get the "S-HD" gears.

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Yes. In my communications with them they had none of the gears to sell, and wouldn't say exactly what they were "just in case plans change".

Hello,
As a relatively fast street car data point:

My car is a 92 talon awd 5 speed. It is pretty heavy still (has power windows, tape deck (ha), power steering etc). I run a br stage 3 engine with a self ported head/fp5r 11r cams, shearer header, 2150s (2x 044s in tank) aem etc. and up until a few months ago a bb6766 (t3). I have gone as fast as 9.8 at almost 154mph with a 6765. I since went with a 6766 turbo,and for several years I have had the the boost at a minimum of about 45psi on the street (e98) and take it out on nice days for some "spirited driving". I just ( about 2 months ago) switched to an fp super99 turbo. The second time I had it out at low boost (38 psi) it stripped off 3rd. This was the jacks full super hd trans with rem treatment. The trans lasted me over 2 years and 2 dsm shootouts. I usually could trap in the low to mid 150mph range basically rolling out and then hitting the gas in the 1/4 mile with the 6766. When it broke with the new turbo it was still shifting perfectly. When I removed the transmission I noticed that the input shaft was twisted and was about to snap off (evo3) as well as third gear being broken.

I think mine was kind of an extreme case as most people would have lightened things up a lot more and maybe would not run the thing at high boost on the street. I can say that I went through several other transmissions before this one and the jacks held up best by far. I followed their oil recommendations and everything. It is too bad they no longer offer this option, as I just didnt want to go dogbox with this street car and felt this to be the next best option for me.

They just repaired the trans for me so I will see how it does at the dsm shootout. Unfortunately the unit was outside of the 14 month warranty when it let go, but they did what they could for me. Maybe if I would have sent it back this winter I would have not broken it, but ya cant be sure.

Thanks.

All,
I went to the dsm shootout this weekend with the new/repaired Jacks super hd trans. I experienced a perfectly shifting trans that did not give me any problems at all. I did not go faster than my best pass as I never launched it harder than a 1.9 60ft (went 10.4 at 149.99 - at low boost). I did turn up the boost in competition, but bogged so badly that i wouldn't even consider the run worth noting. So far so good with the repaired trans.

Thanks,
Erik

erikoberdorfer said:

All,
I went to the dsm shootout this weekend with the new/repaired Jacks super hd trans. I experienced a perfectly shifting trans that did not give me any problems at all. I did not go faster than my best pass as I never launched it harder than a 1.9 60ft (went 10.4 at 149.99 - at low boost). I did turn up the boost in competition, but bogged so badly that i wouldn't even consider the run worth noting. So far so good with the repaired trans.

Thanks,
Erik

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Nice job.

Thats movin for getting the 60's i get

Yes I saw them at the shoot out they aren't completely done with dsm they told me. Down the road they want to continue with them.

In sure someone will CNC sole trans gears... When demand goes up someone will fill in the gaps. Prob won't be cheap at all though, but I'd rather pay to play then be out a trans completely.... For good

iugrad92turbo said:

Yes I saw them at the shoot out they aren't completely done with dsm they told me. Down the road they want to continue with them.

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I don't see why they would. It's not like the DSM crowd will become less frugal in the future, nor will parts availability become less scarce.

They probably just told you the same thing I would have told any disappointed DSM owner. I'm sure they want to continue servicing the DSM community as they have in the past, but I doubt they ever will...Now, or in the future.

GST with PSI said:

I don't see why they would. It's not like the DSM crowd will become less frugal in the future, nor will parts availability become less scarce.

They probably just told you the same thing I would have told any disappointed DSM owner. I'm sure they want to continue servicing the DSM community as they have in the past, but I doubt they ever will...Now, or in the future.

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They mean only servicing the cluster gears for those who build their own transmissions!

keltalon said:

They mean only servicing the cluster gears for those who build their own transmissions!

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They never discontinued this service. According to their website (and the last time I emailed them), they still offer cluster build services. Of course, this will go away as well as parts become unavailable.

I was referring to full trans builds in my initial post; I doubt they will ever return to Jacks' menu.

I just cracked another 1g awd trans open today and its the early 91. Has the center diff with no hash marks on the outer gear (housing is mint, upper pinion thrust washer was welded to the shaft), the aluminum 5th/rev shift fork, and the "HD" gears. This center diff will work in the evo 1 and 90 awd transmissions as the outer gear profiles are the same. I'm excited woot I have 2 90 transmission I need to tear into yet. Visually inspecting the "HD" vs the standard 92+ side by side I would bet the "HD" gears are more durable, the teeth look thicker from the base to tip. Maybe tomorrow I will get the calipers out and be more precise.

If the 90 and early 91 center diff works with the evo 1. Then can the input and intermediate shafts be used in the evo 1?

The center diff housing is not the same as Evo 1; there were a very small number of super early Evo 1's that had 1990 style gears, same goes with the early USDM 91 GVR4's and JDM GVR4's.

This sort of thing scares me, I have slowly been building my car for years. And have watched more and more vendors and nice parts become unavailable. Makes me wonder when in the future If/when I break something Wtf I am going to do

Thanks guys! That was very interesting morning read. Hopefully it won't came to the point were we won't be able to find replacement parts for our cars.

Ripper I felt the same way so I've started to stockpile essential parts.

The center diff that came out of my evo 1 was the same as the early 91. It had the single tab on the lower oiling washer. I used a mint center diff out of a 90 dsm trans in the evo 1 because at the time I didn't have a good early 91. All 3 had the same profile on the outer housing gear(90,early 91, and one I pulled from the evo). The 92+ center diff would not work. Someone could have changed the diff from a 90 style to the early 91(one with no hash marks on the outer gear)? Trans is stamped WQNK and had the steel shift forks without any pads that ride on the hubs. Its very difficult to find any info on the evo 1. I did find out that the early 91 trans front pinion is slightly smaller in diameter than a 92+ and you cannot mix and match the pinion and front diff ring gear, and that the early 91 center diff has the same housing gear profile as the 90. After the build I found on jack's site where he talks about the differences in the center diff, early 91 vs late 91-99. Pic of the early 91 center diff.

Yeah, the Evo 1 output pinion shaft and ring gear are not interchangeable with DSM parts as a mix/match; the ratio is different even though the tooth count is the same on the pinion shaft, the diameter and profile is different.

Like I said, there were a very small number of 1990-style early gearsets used in the Evo 1. I have had a couple over the years and have seen alot of early JDM GVR4's with the same gear profiles; but most of the Evo 1, and all of the Evo 2/3 transmissions use the later tooth profile the same as the 91.6-1999 DSM gears.