F40 Transmission - Will It Work?

Desert Sasqwatch

Goblin Guru
Greetings,
Several members have made this query in the past, whether or not the F40 transmission will work in the Goblin chassis. I can assume at least several other DFG members may be thinking the same way, having a F40 more readily available than a F35.

The only actual trial fitting information I have found so far came from KJP in a build post May 2018. There was no follow up in the post. I made a query in this post, do not know if he has been successful or not?

If any member has this experience, please, share information, measurements, photos, anything that could help provide guidance to decision on the F40 transmission as a viable installation alternative to the F35.
Thanks.
 

Karter2026

Goblin Guru
I spoke with KJP back in early December. At that time he had a change in job position and was short on time to work on the car. As far as I know that last post is as far as he has gotten on it. Another member also was looking to install the F40 but has not gotten that far either. http://dfkitcar.com/forum/index.php?threads/f40-transmission.903/#post-15717
I'm sure it can be done, but it is not going to be a bolt in. You will need some fabrication skills and tools.
 

Desert Sasqwatch

Goblin Guru
Ron, thanks for the reply and link. I have the fab skills and my neighbor builds sand drag chassis, so the tools are no problem. just looking for anyone else's input for their experiences if it has been tried already. Regards, Tim
 

IDRVSLO

Goblin Guru
I believe the main issue is the fitment wont work without modification on the driver side frame. It will hit I believe.
 

KLMOTORSPORTS

Well-Known Member
I was texting with KJP and it is a tight fit (about a 1/4” to spare), but does fit without frame modification...definitely have to use solid mounts everywhere and the drivers side mount has to be modified.

I will be putting the F40 in mine as the F35 is very, very, VERY expensive to repair if needed and I want the added strength of the F40 since mine will be race only (not street legal).
 

Desert Sasqwatch

Goblin Guru
IDRVSLO, thanks for the info.

Ken, I see from your build log you got the F35 with your donor, is it trashed? Have you purchased a F40 yet? I was looking at some Saab 9-3 part outs, especially to get the 6 speed shifter. I am also looking a new transmission, but this will need the clutch/pressure plate/flywheel and the LSD purchase - but it would be a brand new transmission to go with my brand new LNF I just picked up about a week ago.

Yes, I agree that rebuilding the F35 is an expensive proposition and I have read that working on it requires several special tools to do the rebuild work. I would attempt to rebuild one, if not for all these tools needed. The F40, on the other hand, appears to be a very straight forward unit to work on - much like rebuilding a M-22 Muncie, just more gears. A YouTube video showing a rebuild is pretty convincing evidence of this.

If there is enough evidence that the F40 will fit, even with some minor modification to the chassis, I will be committing to this drivetrain set up for my SS/TC build.

I am still trolling for anyone else's input and experience if this has been attempted.
Thanks.
 

KLMOTORSPORTS

Well-Known Member
I just ordered new F40 and F40 Kit from ZZP (about $3200 total with axles) and will use my car as a test case to have my mounts modified while car being built at DF. I’m confident it will work without modifying frame through discussion with KJP and Adam...I think it would be cool to come out of the project with a bolt in kit for the Goblin, but believe at a minimum it will take an entire new left mount off the frame.
 

Brian74

Goblin Guru
Take additional consideration in the fact that the F35 transmission would be going into a car that weighs less than 1/2 of the car that transmission was designed for. There are also a multiude of these transmissions still out there, because most of them outlast the cars they came from. From a cost and fabrication standpoint, how many F35’s can you buy for the cost of a new F40?

I would see a benefit in the F40 for different gear ratios but not sure if there are any options for that.

Just my .02...
 

KLMOTORSPORTS

Well-Known Member
There are all kinds of considerations for sure that should be weighed out...the F40 is the best option for me after weighing all of these considerations, but probably not for everyone...fun stuff
 

Desert Sasqwatch

Goblin Guru
Everyone has their own take on what their Goblin is to them and what parts they want to use to make it their own. This is the magic of building your own car and trying different things to see if they will work. This is a major reason why I chose to start down the path to building a Goblin, it will not be anyone else's build. It's all good!
 

Tinkles

Well-Known Member
It's been cold up here in PA and my garage doesn't have heat are my excuses as to why I have no progress to show. I am debating on picking up a spare block to mock up the F40 in the chassis(don't want to risk damaging my built engine) or just crossing my fingers and shoving it in.
 

KLMOTORSPORTS

Well-Known Member
I would like to keep information flowing here for those installing the F40 in their cars...think we can really help each other out as we progress....thanks!!

Ken
 

Desert Sasqwatch

Goblin Guru
If we could get KJP to chime, we could get his insight, since it seems he has already done the trial fit. Things like axle length, engine positioning (shift front/rear/sideways) and anything else relevant to making the F40 installation a success would help us all.
 

Tinkles

Well-Known Member
From what I know from talking with ZZP about their F40 swap kit is that the stock driveside axle will not work. They include a new driveside axle with the inner stub for the F40 splines and outer stub for the LNF hubs. The passenger side uses a stock LNF axle because they include a new halfshaft. I think the axle length doesn't really change just the splines. But keep in mind that my ZZP F40 swap kit is still boxed up sitting on the floor.
 

Desert Sasqwatch

Goblin Guru
This is good information to know about the drive axles. I'm now curious if Saab hubs, in place of the LNF hubs, would work with the 'stock' F40 axles and the Saab spline count? Or possibly Regal GS axles with the GS hubs, but these may be too long? I'm trying to weigh all my options, since I can pickup a F40 (new) with a dual mass GMPP flywheel/clutch assy (new) for less than $1K, plus a shifter, jackshaft, and axles (Saab) for less than $600 - a difference of about $200 with the ZZP F40 conversion kit ($1.8K) that does not include the transmission , but my purchases do not come with the shifter cables (which would have to be changed out anyway). BTW push/pull shifter cables can be obtained from Jegs and other suppliers for about $300 a pair in a number of standard lengths. Of course the F35 crowd will point out the lack of LSD, but this can be purchased for about $1.2K (with bearings). This path totals out to about $3K for 100% new parts. Trolling the F35 rebuilds, that have a 400nM capacity (F35 Stage 1 build) are more than $3K. This is just something to think about - 100,000+ mile used (worn) F35 versus a $3K+ rebuilt F35 versus a new F40 - I'm inclined to use the new parts in my new car.
 

Desert Sasqwatch

Goblin Guru
Kyle, I read where you have a Quaife for your F40, did you order the trans that way or order the Quaife separately from the trans? Where did you order from? I'm guessing about $1200 with bearings and seals?
 

Tinkles

Well-Known Member
I got the Quaife from B3 Designs. It was $1100 and $300 for their install kit(new bearings, shims, seals, gasket maker, new bolts), so $1400 shipped is what I paid. I do not know if that was their regular price or not. A friend tagged me in their Facebook post advertising that they were getting a few more Quaife diffs in stock and I jumped on it.

My F40 is a low milage used one that I found on ebay that I had shipped to my house. I have had it for awhile now so I forget exactly how much I paid for it but I want to say either $600 or $800. From the research that I have done into the F40 I am pretty sure none of them(for the Ecotecs) came with a factory LSD.
 

Desert Sasqwatch

Goblin Guru
Kyle, I know the halfshaft anf axles for the F40 come in the ZZP kit, but can I ask for some info about these?

Sorry, I know this will be a pain, but need to know the spline count on the driver's side axle, both ends - the transmission end and the hub end? Also the spline count on transmission end of the halfshaft, in case GM did something unusual between the outputs from the trans?

What are the compressed lengths of the drivers and passenger side axles? Need to know if these are the same length or slightly different?

I'm having a hard time finding the correct halfshaft that says it will mate with the F40, but also bolt up to the 2.0 liter block (LNF). The GM catalog states they discontinued manufacturing the LNF/LSJ halfshaft assembly (1/2 axle, bracket/bearing). I may end up using a Buick Regal CXL turbo halfshaft, if I can determine the pillow bearing support has the right bracket bolt pattern.

I do plan to use the Cobalt SS 5 bolt hubs on my car, since I have a line on a set of 17X8 front/17X9 rear 5X110 wheels that I really like.

I'm finalizing my research before plunking down the $$$ for a new F40 and you have been very helpful providing your current experiences and information. Thanks.
 

KLMOTORSPORTS

Well-Known Member
I’ll be picking up my F40 trans and ZZP Kit (with Driveshaft Shop axles) in April from DF after the build/F40 install (having all shipped straight down to DF)...I know it won’t help you now, but can supply info you are looking above then if ya like. Will also provide pictures of install/modifications of my car...I think it is going to work out very well both from install and performance...

Ken
 

Desert Sasqwatch

Goblin Guru
Ken, yes that would be helpful to me and everyone who may be viewing this thread. The more info we share in the forum, the better off we will all be who decide to go the F40 route. I'm sure I will have pulled the trigger on an F40 trans by then and will be proving what info I've learn as I move deeper into my parts purchasing plan. I'm the type of person who will try to gather every tidbit of information before jumping into anything - an engineering character trait.

Question: did you get the Regal or the Saab F40? The more I read about these I m finding there are some significant differences both internally and externally. The bolt pattern on the bellhousing - Ecotec versus Metric, output splines, ring and pinion gears and several others.
Thanks, Tim
 
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