Shift linkage

All things specracer!

New Member
New Member
Posts: 3
Joined: Fri May 03, 2019 10:20 am
PostPosted: Wed Jul 31, 2019 2:31 pm
Brand new SRF3 owner. Loving the car, need to do some minor tweaking until it's perfect for me. Definitely smitten with the whole thing. Where has this been all my racing life? :D Please pardon the very ignorant question. So...about the shift linkage. I've rented some SRF's, driven others, none of them have super-tight shifters. Mine seems to be a little sloppier than average, not horrible. The race-car builder/fabricator in me desperately wants to improve it. I know everything on our cars is technically spec, but is it legal to improve the linkage with some machined parts? Even like putting bushings or better materials at the joints and fasteners? I can't find anything addressing it in the GCR. I will readily admit I haven't studied the entire giant document, just skimmed the general stuff and studied the SRF and SRF3 sections well. It's not really directly addressed that I can find. Thanks for any info.

Still Learning to Type
Still Learning to Type
Posts: 36
Joined: Sun Jan 01, 2012 12:21 am
PostPosted: Wed Jul 31, 2019 4:41 pm
My suggestion would be to swap out all of the universal joints with Apex joints. Pegasus racing has them. Mark Fickensher has some well written instructions with part sizes and details about a bushing that you will need.

New Member
New Member
Posts: 3
Joined: Fri May 03, 2019 10:20 am
PostPosted: Thu Aug 01, 2019 10:07 am
So I take that to mean that it is acceptable to improve the linkage a bit? I’m not really trying to gain advantage, it’s more of a comfort thing. I’ve looked at those Apex joints with that very thing in mind. I also think there is a lot to be gained right where the base of the stick meets the shaft.
User avatar
Needs a Life!!!
Needs a Life!!!
Posts: 1191
Joined: Wed Nov 30, 2011 1:38 am
Location: Sunnyvale, CA
Chassis:
068 415
Facebook Page:
http://facebook.com/HSERacing
PostPosted: Tue Aug 06, 2019 11:10 am
You might want to check the GCR. i believe it lists the ujoints as an acceptable mod, not much else.
Dave Harriman
"It looks crazy, I understand. But, we only live once and I am going to give it a good try." - Alex Zanardi

Novice Typer
Novice Typer
Posts: 18
Joined: Wed Oct 07, 2015 8:44 am
PostPosted: Tue Aug 06, 2019 9:09 pm
From 9.1.8 of the GCR

j. The shifter assembly and all linkages must be installed as per the RFSRII. It is permissible to alter the
length of the shift lever handle above its upper pivot to tailor to driver preference. It is permissible
to use the appropriate Torrington or Apex joint in place of the original Borgeson joint at the specified
installation location in the shift linkage.

New Member
New Member
Posts: 3
Joined: Fri May 03, 2019 10:20 am
PostPosted: Tue Aug 06, 2019 11:19 pm
Thanks for the information. That's exactly what I needed to know. Looks like the joints are all that are (semi)open. Probably not worth $300 for the minimal benefit.

Needs a Life!!!
Needs a Life!!!
Posts: 334
Joined: Fri Dec 02, 2011 6:02 pm
PostPosted: Wed Aug 07, 2019 12:06 am
(Sullenly throws away the depleted uranium shift linkage I just machined)
"Ah shucks, I thought I found a way to get more weight behind the rear axle"
User avatar
Needs a Life!!!
Needs a Life!!!
Posts: 1191
Joined: Wed Nov 30, 2011 1:38 am
Location: Sunnyvale, CA
Chassis:
068 415
Facebook Page:
http://facebook.com/HSERacing
PostPosted: Wed Aug 07, 2019 10:18 am
DoctorHoon wrote:Thanks for the information. That's exactly what I needed to know. Looks like the joints are all that are (semi)open. Probably not worth $300 for the minimal benefit.

I think the helicopter joints are more durable. You should check the u-joints for play, also where the roll pins go through the shafts.
There are also boots available to keep the dirt out and lubrication in.
Dave
Dave Harriman
"It looks crazy, I understand. But, we only live once and I am going to give it a good try." - Alex Zanardi

New Member
New Member
Posts: 7
Joined: Thu Aug 01, 2013 8:14 am
PostPosted: Wed Aug 07, 2019 2:45 pm
"Mark Fickensher has some well written instructions with part sizes and details about a bushing that you will need" Where would one find these instructions? Used search and can't find anything.

Forum Hermit
Forum Hermit
Posts: 120
Joined: Thu May 30, 2013 6:36 am

Chassis:
577
PostPosted: Wed Aug 07, 2019 9:16 pm
Mark helped me with mine... Here is a synopsis from my conversion.
All credit goes to Mark. I could not have done it without his guidance and experience.

I had trouble drilling the steel inserts; tried them first.
I had bought alternative materials, Nylon and another resin.
The Nylon melted from heat I generated drilling, and the resin material ended up working; that was best for me.
I have a few spares in case it wears out.
20 race weekends later, no slop in the shifting, so its resin version is working well for me.


-----

The Apex joints are from Pegasus
two of the 3/4" ones.
The McMaster Carr inserts are needed because the front shift rod is 1/2".
You have to drill out carefully the front insert for the shifter rod using a 1/2" drill bit ( get a good one!)
(Wasn't easy to do; I had to do it twice)

Strengthen the Apex joint where our large bolt goes through on the rear.
Carefully drill out for the large rear bolt ( 1/2" )going though both the Apex joint and the insert from McMaster Carr.
The bolts and nuts are grade 8
They are 1/4" bolts and nuts grade 8.
bolt up with the saddle washers to make them hold the Apex joints better.

The black piece and bolt are furnished with the old Gen2 and now the new Gen3 kits in order to connect to the tranny shifter.
I ended up using my Gen2 black spacer and bolt as I felt they were more rugged. Personal preference.
You need a 1/2" drill bit and 1/4" drill bit. (carbide is best)


--------------------
Parts to Install (2) Apex Joints on a Gen2 or Gen3 shifter rod:

Insert for shifter rod Using Apex Joints: From McMaster Carr:

92415A459
Zinc-Plated Steel Unthreaded Spacer, 3/4" OD, 1" Length, 3/8" Screw Size (need 2)


From Pegasus Racing:
Apex Covered Universal Joint (aka: Helicopter Joints) (need 2)
3/4" MS20271-B14 3 5/8" 7/8" 1" 3000 in-lb 1490-3/4


Also I used 8 of these for the ¼” grade 8 Bolts on the Apex Joints: From Pegasus Racing:

Saddle Washer for 7⁄8'' OD Tubing, 1⁄4'' Bolt
(Apex 3⁄4'' bore joints),. . . . . . . . . .Part No. 3077-003-875
Attachments
Shifter3.jpg
Shifter3.jpg (50.93 KiB) Viewed 805 times
Shifter2.jpg
Shifter2.jpg (50.36 KiB) Viewed 805 times
Shifter1 (3).jpg
Shifter1 (3).jpg (59.93 KiB) Viewed 805 times
Scott Cypher
SRF3 #577 G3
Next

Return to General Discussions

Who is online

Users browsing this forum: No registered users and 10 guests